Nuclear Regulatory Commission
Oversight of Underground Piping Systems Commensurate with Risk, but Proactive Measures Could Help Address Future Leaks Gao ID: GAO-11-563 June 3, 2011All U.S. nuclear power plant sites have had some groundwater contamination from radioactive leaks, and some of these leaks came from underground piping systems. The Nuclear Regulatory Commission (NRC) regulates nuclear power plants to protect public health and the environment from radiation hazards. GAO was asked to (1) determine experts' opinions on the impacts, if any, of underground piping system leaks on public health and the environment; (2) assess NRC requirements of licensees for inspecting these systems and monitoring and reporting on leaks; (3) identify actions the nuclear power industry, licensees, and NRC have taken in response to leaks; and (4) identify additional NRC requirements, if any, that key stakeholders think could help prevent, detect, and disclose leaks. GAO convened expert discussion groups through the National Academy of Sciences and asked experts to review three case studies, analyzed documents, visited seven plant sites and two NRC regional offices, and interviewed stakeholders..
While experts in our public health discussion group generally agreed that radioactive leaks at the three nuclear power plants in our case studies of actual events had no discernible impact on the public's health, these experts noted that additional information could enhance the identification of the leaks and the characterization of their impacts. The experts in our environmental impact discussion group concluded that environmental resources beyond the plant site have not been impacted discernibly, but that on-site contamination could affect plant decommissioning; for example, the licensee may have to conduct costly remediation to meet NRC regulations for unrestricted release of the site. Experts also identified the need for licensees to transparently report monitoring data and for licensees' groundwater monitoring programs to be independently reviewed. NRC inspection requirements focus on ensuring the functionality of underground piping systems that are essential for both the safe operation and the shutdown of plants rather than providing information about the condition of the underground piping systems. In addition, NRC's groundwater monitoring requirements generally focus on monitoring off-site locations, where a member of the public could be exposed to radiation, but not on onsite groundwater monitoring, which can improve the likelihood that leaks will be detected before they migrate off-site. In response to leaks, the nuclear power industry has implemented two voluntary initiatives to increase public confidence in plant safety. The first initiative was intended to improve on-site groundwater monitoring to promptly detect leaks. The second was intended to provide reasonable assurance of underground piping systems' structural and leaktight integrity. Licensees' responses to detected leaks have varied, ranging from repairing the leak source and documenting the leak's extent, to performing extensive mitigation. In addition, NRC has assessed its regulatory framework for, and oversight of, inspection of underground piping systems and groundwater monitoring. Based on the low risk posed by spills to date, NRC determined that no further regulations are needed at this time but has committed to such actions as gathering information on underground piping leak trends and reviewing codes and standards for underground piping. Key stakeholders identified additional NRC requirements that they thought could help prevent, detect, and disclose leaks. Some saw a need for NRC to require licensees to inspect the structural integrity of underground piping using techniques used in the oil and gas industry, while noting the challenges to applying such techniques at nuclear power plants. Industry is undertaking research to overcome these challenges. Stakeholders also noted that NRC should enhance its on-site groundwater monitoring requirements to promptly detect leaks and minimize their impacts. Finally, stakeholders said that NRC should require licensees to provide leak information in a more timely fashion and should make that information more accessible to the public. GAO recommends that NRC periodically assess the effectiveness of the groundwater initiative and determine whether structural integrity tests should be included in licensee inspection requirements, when they become feasible, based on industry research. NRC stated it agrees with the report and recommendations and asserted that NRC has taken relevant actions.
RecommendationsOur recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Open," "Closed - implemented," or "Closed - not implemented" based on our follow up work.
Director: Franklin W. Rusco Team: Government Accountability Office: Natural Resources and Environment Phone: (202) 512-4597GAO-11-563, Nuclear Regulatory Commission: Oversight of Underground Piping Systems Commensurate with Risk, but Proactive Measures Could Help Address Future Leaks
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United States Government Accountability Office:
GAO:
Report to Congressional Requesters:
June 2011:
Nuclear Regulatory Commission:
Oversight of Underground Piping Systems Commensurate with Risk, but
Proactive Measures Could Help Address Future Leaks:
GAO-11-563:
GAO Highlights:
Highlights of GAO-11-563, a report to congressional requesters.
Why GAO Did This Study:
All U.S. nuclear power plant sites have had some groundwater
contamination from radioactive leaks, and some of these leaks came
from underground piping systems. The Nuclear Regulatory Commission
(NRC) regulates nuclear power plants to protect public health and the
environment from radiation hazards. GAO was asked to (1) determine
experts‘ opinions on the impacts, if any, of underground piping system
leaks on public health and the environment; (2) assess NRC
requirements of licensees for inspecting these systems and monitoring
and reporting on leaks; (3) identify actions the nuclear power
industry, licensees, and NRC have taken in response to leaks; and (4)
identify additional NRC requirements, if any, that key stakeholders
think could help prevent, detect, and disclose leaks. GAO convened
expert discussion groups through the National Academy of Sciences and
asked experts to review three case studies, analyzed documents,
visited seven plant sites and two NRC regional offices, and
interviewed stakeholders.
What GAO Found:
While experts in our public health discussion group generally agreed
that radioactive leaks at the three nuclear power plants in our case
studies of actual events had no discernible impact on the public‘s
health, these experts noted that additional information could enhance
the identification of the leaks and the characterization of their
impacts. The experts in our environmental impact discussion group
concluded that environmental resources beyond the plant site have not
been impacted discernibly, but that on-site contamination could affect
plant decommissioning; for example, the licensee may have to conduct
costly remediation to meet NRC regulations for unrestricted release of
the site. Experts also identified the need for licensees to
transparently report monitoring data and for licensees‘ groundwater
monitoring programs to be independently reviewed.
NRC inspection requirements focus on ensuring the functionality of
underground piping systems that are essential for both the safe
operation and the shutdown of plants rather than providing information
about the condition of the underground piping systems. In addition,
NRC‘s groundwater monitoring requirements generally focus on
monitoring off-site locations, where a member of the public could be
exposed to radiation, but not on on-site groundwater monitoring, which
can improve the likelihood that leaks will be detected before they
migrate off-site.
In response to leaks, the nuclear power industry has implemented two
voluntary initiatives to increase public confidence in plant safety.
The first initiative was intended to improve on-site groundwater
monitoring to promptly detect leaks. The second was intended to
provide reasonable assurance of underground piping systems‘ structural
and leaktight integrity. Licensees‘ responses to detected leaks have
varied, ranging from repairing the leak source and documenting the leak‘
s extent, to performing extensive mitigation. In addition, NRC has
assessed its regulatory framework for, and oversight of, inspection of
underground piping systems and groundwater monitoring. Based on the
low risk posed by spills to date, NRC determined that no further
regulations are needed at this time but has committed to such actions
as gathering information on underground piping leak trends and
reviewing codes and standards for underground piping.
Key stakeholders identified additional NRC requirements that they
thought could help prevent, detect, and disclose leaks. Some saw a
need for NRC to require licensees to inspect the structural integrity
of underground piping using techniques used in the oil and gas
industry, while noting the challenges to applying such techniques at
nuclear power plants. Industry is undertaking research to overcome
these challenges. Stakeholders also noted that NRC should enhance its
on-site groundwater monitoring requirements to promptly detect leaks
and minimize their impacts. Finally, stakeholders said that NRC should
require licensees to provide leak information in a more timely fashion
and should make that information more accessible to the public.
What GAO Recommends:
GAO recommends that NRC periodically assess the effectiveness of the
groundwater initiative and determine whether structural integrity
tests should be included in licensee inspection requirements, when
they become feasible, based on industry research.
NRC stated it agrees with the report and recommendations and asserted
that NRC has taken relevant actions.
View [hyperlink, http://www.gao.gov/products/GAO-11-563] or key
components. For more information, contact Frank Rusco at (202) 512-
3841 or ruscof@gao.gov.
[End of section]
Contents:
Letter:
Background:
According to Experts, Underground Piping Leaks at Three Nuclear Power
Plants Had No Discernible Impact on Public Health or the Environment,
but More Information Could Enhance Identification of Leaks and
Characterization of Their Impacts:
NRC Requires Licensees to Inspect the Function of Their Safety-Related
Underground Piping Systems, Monitor the Plant Environs for Radiation,
and Report Releases in a Timely Manner:
The Nuclear Power Industry, Licensees, and NRC Have Taken a Variety of
Actions in Response to Underground Piping Leaks:
Several Stakeholders Recommended That NRC Enhance Its Inspection,
Groundwater Monitoring, and Reporting Requirements:
Conclusions:
Recommendations for Executive Action:
Agency Comments and Our Evaluation:
Appendix I: Objectives, Scope, and Methodology:
Appendix II: Case Studies for Experts' Consideration:
Appendix III: Comments from the Nuclear Regulatory Commission:
Appendix IV: GAO Contact and Staff Acknowledgments:
Tables:
Table 1: Radiation Protection Limits:
Table 2: Nuclear Power Plant Site Visits:
Table 3: Summary of Underground Piping System Leak Case Studies:
Table 4: Braidwood Land Use Survey Results:
Table 5: Doses to the Public from Vacuum Breaker Releases (mrem/yr):
Table 6: Oyster Creek Generating Station Land Use Survey Results:
Table 7: Vermont Yankee Land Use Census Results:
Figures:
Figure 1: U.S. Operating Commercial Nuclear Power Reactors:
Figure 2: Hypothetical Radioactive Leak from a Nuclear Power Plant
Underground Piping System.
Figure 3: NRC Regional Offices:
Figure 4: Braidwood Generating Station:
Figure 5: Oyster Creek Generating Station:
Figure 6: Location of Oyster Creek Generating Station:
Figure 7: Oyster Creek Generating Station Site Boundary:
Figure 8: Oyster Creek Well Locations Associated with Buried Pipe Leak:
Figure 9: General Location of Vermont Yankee Nuclear Power Station:
Figure 10: Site Location Photo of Vermont Yankee Nuclear Power Station:
Abbreviations:
AOG: Advanced Off-Gas:
ASME: American Society of Mechanical Engineers:
BWR: Boiling Water Reactor:
cfs: cubic feet per second:
EPA: Environmental Protection Agency:
ESW: Emergency Service Water:
Fe-55: Iron-55:
GPM: gallons per minute:
kg/yr: kilograms per year:
L/yr: Liters per year:
MDA: minimum detectable activity:
MOU: memorandum of understanding:
mrem: millirem:
mrem/yr: millirem per year:
MWt: megawatts-thermal:
Ni-63: Nickel-63:
NPDES: National Pollutant Discharge Elimination System:
NRC: Nuclear Regulatory Commission:
pCi/L: picocuries per liter:
NEI: Nuclear Energy Institute:
OCGS: Oyster Creek Generating Station:
PWR: Pressurized Water Reactor:
Sr-90: Strontium-90:
Te-99: Technetium-99:
Vernon Dam: Vernon Hydroelectric Dam:
VYNPS: Vermont Yankee Nuclear Power Station:
[End of section]
United States Government Accountability Office:
Washington, DC 20548:
June 3, 2011:
The Honorable Edward Markey:
The Honorable Peter Welch:
House of Representatives:
In recent years, a number of nuclear power plants have experienced
leaks of radioactive materials from pipe systems that are underground
and not easily accessible. Many of these underground pipe leaks
resulted in contamination of groundwater by tritium--a radioactive
form of hydrogen. In some instances, the contamination has migrated,
or is expected to migrate, beyond the plant's boundaries, raising
concerns about potential impacts on public health and the environment.
The Nuclear Regulatory Commission (NRC), an independent federal agency
headed by five commissioners, licenses commercial nuclear power plants
and regulates and oversees their safe operation and security. NRC's
mission includes protecting public health and the environment from
radiation hazards.
Most nuclear power plants have extensive underground piping systems,
[Footnote 1] some of which transport water containing radioactive
isotopes, such as tritium. While the amount and type of underground
piping systems vary significantly among nuclear power plants,
according to NRC officials, most of these underground systems are not
safety-related--that is, they are not necessary to ensure reactor
integrity, shut down and safely maintain the reactor, or prevent or
mitigate the public's exposure to radiation during an accident. As
nuclear power plants age, their underground piping systems tend to
corrode, but since these systems are largely inaccessible and
difficult to inspect, the condition of many underground piping systems
at plants across the country is unknown. Further, as pipes continue to
age and further corrosion occurs, the likelihood and severity of leaks
could increase without mitigating actions.
In the past decade, increased reports of buried pipe leaks at nuclear
power plants have attracted significant attention and generated public
concern about NRC's oversight of underground piping systems,
particularly since NRC has issued few violations in association with
these leaks.[Footnote 2] Specifically, stakeholders--such as
environmental and antinuclear groups, as well as some scientists and
engineers--have questioned the adequacy of NRC requirements pertaining
to the safety of underground piping systems and are also seeking to
understand the factors responsible for underground piping system
leaks. Some stakeholders also have concerns about NRC's license
renewal process. As most aging power plants have been applying for--
and receiving--20-year extensions of their operating licenses, some
stakeholders have filed contentions, including contentions to prevent
the relicensing of some plants with underground piping systems that
may be subject to leaks.[Footnote 3]
In this context, you asked us to review underground piping systems and
NRC's requirements for them. Our objectives were to (1) determine
experts' opinions on the impacts, if any, that underground piping
system leaks have had on public health and the environment; (2) assess
NRC requirements of licensees for inspecting underground piping
systems and monitoring and reporting on leaks from these systems; (3)
identify actions the nuclear power industry, licensees, and NRC have
taken in response to underground piping system leaks; and (4)
identify, according to key stakeholders, what additional NRC
requirements, if any, could help prevent, detect, and disclose leaks
from underground piping systems.
To address these objectives, we consulted with experts, analyzed
documents, conducted visits to selected plant sites and NRC regional
offices, and interviewed stakeholders. Specifically, we worked with
the National Academy of Sciences to convene two groups of six experts
each,[Footnote 4] in January 2011. The first group addressed the
public health impacts of underground piping system leaks, and the
second one addressed their environmental impacts. We asked both groups
of experts to discuss the impacts of leaks in the context of three
case studies of nuclear power plants that have experienced leaks in
their underground piping systems: Braidwood Generating Station in
Illinois, Oyster Creek Generating Station in New Jersey, and Vermont
Yankee Nuclear Power Station in Vermont.[Footnote 5] We selected these
case studies because they included plants with underground piping
system leaks that generated significant publicity and resulted in high
concentrations of tritium detected in on-site groundwater.
Additionally, the case studies included a plant at which contamination
from a leak was detected off-site (Braidwood). We also analyzed
relevant NRC regulations and requirements and interviewed NRC
officials from the Office of Nuclear Reactor Regulation, Office of
General Counsel, Region I, and Region III. In addition, we selected a
nonprobability sample[Footnote 6] of seven nuclear power plants, most
of which had recently experienced an underground piping system leak,
and one of which had not experienced a publicized pipe leak, and made
site visits to these locations to interview licensee representatives
and NRC resident inspectors. During the site visits, we also observed
ongoing activities related to mitigation of leaks. Finally, using a
standard set of questions, we interviewed a nonprobability sample of
over 30 stakeholders including representatives from NRC, other federal
and state agencies who have worked on issues related to underground
piping system leaks and associated groundwater contamination,
representatives from industry and industry groups, standards-setting
organizations, and advocacy and other interested groups, as well as
independent consultants and experts. A more detailed description of
our objectives, scope, and methodology is presented in appendix I. We
conducted this performance audit from May 2010 to June 2011, in
accordance with generally accepted government auditing standards.
Those standards require that we plan and perform the audit to obtain
sufficient, appropriate evidence to provide a reasonable basis for our
findings and conclusions based on our audit objectives. We believe
that the evidence obtained provides a reasonable basis for our
findings and conclusions based on our audit objectives.
Background:
Currently 104 commercial nuclear power plants operate in the United
States, together generating, as of 2007, about 20 percent of our
nation's electricity. These reactors are located at 65 sites across
the country (see figure 1) and are operated by 26 different companies.
Many reactors built in the late 1960s and early 1970s are reaching or
have reached the end of their initial 40-year license. As of March
2011, NRC had renewed 63 reactor licenses for an additional 20 years
and was currently reviewing 19 license renewal applications.
Figure 1: U.S. Operating Commercial Nuclear Power Reactors:
[Refer to PDF for image: illustrated U.S. map]
The map depicted the location of commercial nuclear power reactors, as
follows:
Years of commercial operation by the end of 2010: 10-19;
Number of reactors: 3.
Years of commercial operation by the end of 2010: 20-29;
Number of reactors: 48.
Years of commercial operation by the end of 2010: 30-39;
Number of reactors: 46.
Years of commercial operation by the end of 2010: 40 or more;
Number of reactors: 7.
Sources: NRC (data); Map Resources (map).
[End of figure]
Since 2008, NRC has been collecting data from licensees on groundwater
contamination incidents at nuclear power plants that have resulted
from unplanned or uncontrolled releases of radioactive material,
including leaks from underground piping systems. Based on these data,
NRC has concluded that all 65 reactor sites in the United States have
experienced a leak or spill of radioactive material into groundwater.
NRC estimates that between 10 and 20 percent of groundwater
contamination events at nuclear power plants can be attributed to
leaks from underground piping systems.[Footnote 7] Figure 2 provides a
diagram of a hypothetical underground piping system leak at a nuclear
power plant. In addition, NRC data suggest that groundwater
contamination events have been more prevalent during the last several
years; however, the agency attributes this apparent increase to the
nuclear industry's enhanced monitoring efforts and increased reporting
of leaks during the same time period.
Figure 2: Hypothetical Radioactive Leak from a Nuclear Power Plant
Underground Piping System:
[Refer to PDF for image: illustration]
Nuclear power plant:
Damaged pipe:
Tritium plume within sand and stone layer beneath plant, detected by
Monitoring well.
Below sand and stone layer are:
upper clay;
lower clay;
Aquifer.
Source: NRC.
[End of figure]
NRC strives to accomplish its mission of protecting public health and
safety and the environment by establishing regulations and standards
governing licensed activities and inspecting facilities to ensure
compliance with requirements. NRC prioritizes its oversight and
inspections of structures, systems, and components that are critical
to safely operating the plant during normal conditions and safely
cooling the reactor core in the case of an emergency shutdown.
Therefore, these structures, systems, and components are classified by
NRC as "safety-related."
NRC maintains staff at commercial nuclear power plants to inspect,
measure, and assess their safety performance--and respond to any
deficiency in performance--through its Reactor Oversight Process.
Furthermore, according to NRC inspection protocols, performance
deficiencies by the company licensed to operate a nuclear power plant,
or licensee, can result in more intensive NRC oversight and/or
issuance of a violation. However, to assure licensees that
requirements placed on them will change only when they are justified
from a public health and safety standpoint, the "backfit rule"
[Footnote 8] requires that NRC make the determination that new
requirements will result in a substantial increase in the overall
protection of public health and safety and that this increased
protection justifies the cost of implementing the new requirement.
[Footnote 9]
NRC's regulations allow certain levels of radioactive materials to be
discharged into the environment. As a part of its license application,
a licensee performs calculations of its expected releases,[Footnote
10] and NRC reviews these calculations to verify their validity and
conformance to NRC requirements. NRC's review and verification are
documented in reports,[Footnote 11] and the licensees are required to
monitor their discharges. Most of the systems used to discharge these
radioactive materials are not classified as "safety-related."
According to NRC officials, the amount of radioactive materials
released from underground piping system leaks has been small relative
to these permitted discharges. Furthermore, the officials noted that a
leak of tritium in and of itself is not a violation of NRC
requirements.
NRC has established several layers of radiation standards to protect
the public against potential health risks from exposure to radioactive
releases from nuclear power plant operations (see table 1). In
addition to these standards, the Environmental Protection Agency (EPA)
developed drinking water standards for radioactive isotopes using its
authority under the Safe Drinking Water Act. These limits apply to
public drinking water systems but are also used by many state
authorities as groundwater protection standards. For tritium, EPA set
a maximum contaminant level of 20,000 picocuries per liter
(pCi/l).[Footnote 12] None of the reported underground piping system
leaks to date have exceeded NRC limits on the public's exposure to
radiation, nor have reported concentrations of radioactive materials
in off-site groundwater exceeded EPA standards for drinking water.
Table 1: Radiation Protection Limits:
Radiation protection layer: As low as reasonably achievable dose
objective for liquid releases[A];
Annual dose limit: 3 millirem (mrem)[B] to the whole body and 10 mrem
to any organ of an individual who lives in close proximity to the
plant boundary;
Basis: A fraction of the natural background radiation dose, and an
attainable objective that nuclear power plants could reasonably meet.
Radiation protection layer: EPA radiation standards incorporated as
NRC regulations[C];
Annual dose limit: 25 mrem to the whole body, 75 mrem to the thyroid,
and 25 mrem to any other organ of an individual member of the public;
Basis: Limit is cost-effective in reducing potential health risks from
nuclear power generation facilities' operation.
Radiation protection layer: NRC dose limit[D];
Annual dose limit: 100 mrem to any individual members of the public;
Basis: International Commission on Radiological Protection[E]
recommendation that a lifetime of exposure at this limit would result
in a very small health risk and is roughly equivalent to background
radiation from natural sources.
Source: NRC.
[A] 10 C.F.R. Part 50, App. I.
[B] A millirem is a unit for measuring biological damage from
radiation.
[C] 10 C.F.R. § 20.1301(e).
[D] 10 C.F.R. § 20.1301(a)(1).
[E] The International Commission on Radiological Protection is an
organization of international radiation scientists who provide
recommendations regarding radiation protection related activities,
including dose limits.
[End of table]
When unplanned releases do not exceed NRC dose limits, NRC
requirements allow for licensees to remediate the residual
radioactivity at the time the site is decommissioned. For a
decommissioned nuclear power plant site to be released for
unrestricted use, NRC requires that it be cleaned up to an established
minimum radiation annual dose limit. In addition to this requirement,
NRC has entered into a memorandum of understanding (MOU) with EPA on
cleanup of radioactively contaminated sites. The MOU includes
provisions for NRC to consult with EPA if a site meets NRC cleanup
standards but exceeds EPA-permitted levels.[Footnote 13]
According to Experts, Underground Piping Leaks at Three Nuclear Power
Plants Had No Discernible Impact on Public Health or the Environment,
but More Information Could Enhance Identification of Leaks and
Characterization of Their Impacts:
According to the experts in our public health discussion group, no
impacts on public health have been discernible from leaks at the three
case study nuclear power plants we asked the expects to consider.
Experts in our environmental expert group also said that no impacts
from these leaks on off-site environmental resources have been
discernible to date but that the on-site impacts over time are less
certain. Finally, experts in both groups believe that additional
information could help facilitate the identification of any future
leaks and characterize their impacts.
According to Experts in Our Public Health Discussion Group, Leaks at
Three Plants Have Had No Discernible Impact on Public Health but May
Have Affected Local Communities in Other Ways:
Radioactive leaks at three power plants in Illinois, New Jersey, and
Vermont have had no discernible impact on the public's health,
according to the participants in our expert discussion group on the
public health impacts of the leaks. More specifically, although the
experts observed that the risk of impacts to the public's health is
not zero, it is immeasurably small. While tritium was detected in the
on-site groundwater at each of these plants from one or more leaks, it
was detected in an off-site drinking water well only in the case of
the Illinois plant. The experts noted that, based on the information
reported by the licensees and NRC on off-site contamination levels,
the radiation doses to the public from leaks at these plants have been
very low--well below NRC regulations for radiation exposure, and
orders of magnitude below any exposure that could cause an observable
health effect.
While the experts concluded that leaks at these plants have not
discernibly impacted the public's health, some of them noted that the
leaks may affect people in the surrounding communities in a less
tangible manner. For example, according to two of the experts, even if
community members have not been exposed to radiation from the leaks,
the perception that contamination could exist in their community or
that they cannot trust the operators of a nearby nuclear power plant
can degrade individuals' quality of life. In addition, another expert
noted that reported leaks at nuclear power plants could have an impact
on the property values in the surrounding community based on the
perception that the leaks could impact public health. Some of the
experts observed that such perceptions are not taken into account in
NRC's regulatory framework, which is based on protecting public health
and safety. However, they noted that, for NRC or licensees to build
trust and gain credibility, they should consider these perceived
impacts when determining their actions to address a leak. A few
experts said that better communication and complete transparency with
the public about the risks associated with very low doses of radiation
would be required to change the public's perception of the impacts
associated with the leaks. However, one expert acknowledged the
difficulty in effectively communicating the complex issue of risks to
the public posed by low doses of radiation. Another expert suggested
that communication with the public may be more effective if it is done
through someone outside of industry with higher credibility from the
community's perspective.
No Impacts on Off-site Environmental Resources from Leaks at the Three
Plants to Date Have Been Discernible, but Future On-site Impacts Are
Less Certain, and Some Risks May Not Be Fully Understood, according to
Experts in Our Environmental Impacts Discussion Group:
Based on the information that is available on the case studies
considered by the experts, the experts in our environmental impacts
discussion group concluded that the leaks have had no discernible
impact on off-site environmental resources. The experts noted that the
leaks are unlikely to have an environmental impact if they do not
affect public health, since humans are probably more sensitive to the
effects of tritium contamination than most other organisms. However,
two experts noted that very little information exists on the
sensitivity of other organisms to impacts from environmental tritium
contamination. Consequently, subtle effects on other organisms that
have not been identified could exist.
A few experts pointed out that even though off-site environmental
impacts are not discernible, the on-site groundwater contamination
from the leaks may have degraded the on-site environment, potentially
limiting the site's future use. The on-site groundwater tritium
contamination resulting from two of the case study leaks was detected
in concentrations over 100 times the EPA drinking water standard.
Consequently, some of the experts noted that when a licensee
decommissions a plant with this level of groundwater contamination,
the licensee may have to conduct costly remediation to be able to meet
NRC regulations for unrestricted release of the site, or the site
could have deed restrictions placed on its future use. Some of the
experts debated whether the time frames for decommissioning current
nuclear power plant sites would be sufficient for existing tritium
contamination to naturally decay to levels required for unrestricted
release of the site.[Footnote 14] Regardless, one of the experts noted
that the licensees and NRC need to monitor high levels of current on-
site contamination and ensure it does not move off-site in the future.
Experts in Both of Our Groups Said That Additional Information Could
Help Facilitate the Timely Detection of Leaks and Characterize Their
Impacts, and Experts Identified the Need for More Transparency and
Independent Review of Information:
According to the experts in both of our discussion groups, to
facilitate the detection of leaks in a timely manner, it is important
that licensees have a thorough understanding of the site's subsurface
environment and identify risk areas. NRC requires characterization of
a site's hydrogeology--the groundwater and other subsurface
characteristics--as a part of the evaluation process to choose an
appropriate site for construction of the nuclear power plant. However,
one expert pointed out that any construction on-site can significantly
modify how groundwater flows through the subsurface, so it is very
important to have current knowledge of a site's hydrogeology. In
addition, experts also said that it was very important for licensees
to have knowledge of their underground infrastructure and to identify
critical systems, structures, and components where a leak might occur.
This knowledge would enable licensees to strategically place their
monitoring wells in order to have confidence that they will promptly
detect leaks.
Additional information could help characterize the impacts of leaks,
according to the experts. More specifically, the experts noted that
industry currently lacks standardized data across nuclear power plants
to characterize the impacts of leaks and that data used to inform
assessments of risk are limited to the locations where samples are
collected. Experts said that, to obtain a complete picture of a leak's
consequences, monitoring wells need to be placed in the proper
locations, which must be informed by a thorough understanding of a
site's hydrogeologic characteristics. Finally, the experts noted that
licensees need to have conservative models that can predict how
contamination would move if a leak were to occur, how long it would
take for contamination to migrate off-site or contaminate a drinking
water well, and what impacts there might be to public health and the
environment.
Finally, experts identified the need for licensees' monitoring data
and assessments of impacts to be more transparent and to be
independently reviewed to provide greater public confidence in them.
One expert noted that groundwater data collected voluntarily by the
licensees should be part of their annual environmental reports.
Another expert observed that the groundwater reports prepared
voluntarily by industry typically oversimplify presented data. In
addition, experts expressed concern that there is no process for an
agency or third party to review licensees' groundwater monitoring
programs. For example, one expert observed that licensees, with their
consultants, independently develop their voluntary groundwater
monitoring programs, collect the data, and report the results without
a formal opportunity for NRC or others to comment on the specifics of
the programs such as the number, location, and depth of monitoring
wells. Another expert noted that the results of licensees' modeling of
radiation doses to the public from a leak should also undergo an
independent review. Such a review could assess whether a different
conclusion might have been reached if, for example, monitoring wells
were placed in a different location. This is important, according to
one expert, because NRC relies on licensees to initially determine
whether a leak presents a health risk.
NRC Requires Licensees to Inspect the Function of Their Safety-Related
Underground Piping Systems, Monitor the Plant Environs for Radiation,
and Report Releases in a Timely Manner:
NRC inspection requirements related to underground piping systems at
all 104 U.S. nuclear power plants focus on ensuring the functionality
of safety-related piping systems, monitoring the plant environs for
radiation, and reporting planned and unplanned releases.[Footnote 15]
Specifically, NRC requires licensees to periodically test a sample of
safety-related piping. Pipes are designated as safety related if they
are essential to safely operate the plant or safely shut it down in
case of an emergency. NRC inspection regulations, through the adoption
of applicable American Society of Mechanical Engineers (ASME) Code
provisions,[Footnote 16] require licensees to perform only pressure
tests or flow tests on their safety-related underground piping
systems. The pressure test is used to determine if and to what extent
pressure is being lost within a section of piping, while the flow test
is designed to identify any reduction in flow volume. To pass these
tests, the pipes must be able to transport fluids at or above a
specified minimum pressure or flow rate, which can be accomplished
even when pipes are leaking. According to NRC, the agency's primary
concern is whether a system is providing enough water to maintain its
functionality at one point in time, which is what the results of the
pressure and flow tests indicate.
NRC regulations also require that licensees monitor the "plant
environs"[Footnote 17] for radioactivity that may be released from
normal plant operations, as well as from unplanned leakage such as
leaks and spills, to ensure the protection of the public's health and
safety. NRC requires that licensees establish and implement a site-
specific Radiological Environmental Monitoring Program to obtain data
on measurable levels of radiation and radioactive materials in the
environment. Consistent with NRC guidance for this required monitoring
program, licensees conduct radiation monitoring at locations where a
member of the public could be exposed to radiation to identify whether
levels of off-site radiation exceed federal dose limits. For example,
agency guidance recommends quarterly monitoring of off-site
groundwater only if it is used as a direct source of drinking water or
irrigation and is likely to be contaminated. The agency does not
generally require that licensees monitor groundwater on-site if it is
not used for drinking water.[Footnote 18] However, if a licensee's
monitoring program found radioactive materials off-site, additional on-
site monitoring could be required. With on-site monitoring, future
leaks and spills have a higher likelihood of being detected before
contamination reaches the site boundaries. Even though NRC has not
generally required licensees to have on-site groundwater monitoring
wells, most plants have installed some on-site wells that could help
detect and monitor leaks. Although some contamination has been found
to migrate off-site, thus far, according to NRC, reported off-site
contamination has not exceeded EPA drinking water standards or NRC
radiation exposure limits.
In addition, NRC regulations require that planned and unplanned
releases be reported to NRC by licensees in a timely manner.[Footnote
19] For example, each licensee must submit a written report to NRC
within 30 days after learning of an inadvertent release above
specified limits of radioactive materials, such as tritium. The
licensee's report must include a description of the extent of exposure
of individuals to radiation and radioactive material. These NRC
reporting requirements are in addition to their immediate notification
of incidents requirements. Immediate notification, via an Emergency
Notification System or telephone, is required for certain events or
situations that may have caused or threatens to cause an individual to
receive a high dose of radiation.[Footnote 20]
The Nuclear Power Industry, Licensees, and NRC Have Taken a Variety of
Actions in Response to Underground Piping Leaks:
In response to underground piping leaks at nuclear power plants, the
nuclear power industry adopted two voluntary initiatives largely
intended, according to the Nuclear Energy Institute (NEI),[Footnote
21] to enhance public confidence in the operation and maintenance of
their plants. The actions specified in these initiatives, according to
NRC officials, are above and beyond NRC requirements. Groundwater
incidents that occurred around the 2005 time frame led to the
industry's Groundwater Protection Initiative in 2007,[Footnote 22]
which was intended to boost public confidence in the safe operation of
the plants and to improve groundwater monitoring at nuclear power
plant sites to promptly detect leaks. All licensees of operating
commercial nuclear power plants in the United States have committed to
the groundwater initiative and, in so doing, have agreed to perform a
site hydrogeologic characterization and risk assessment, establish an
on-site groundwater monitoring program, and establish a remediation
protocol.
After 2007, additional underground piping leaks were reported,
heightening public concern about the degradation of buried pipes at
nuclear power plants. As a result, NEI announced another voluntary
industry initiative in 2009.[Footnote 23] This second initiative--
called the Buried Piping Integrity Initiative--was designed to provide
reasonable assurance of structural and leaktight integrity of all
buried pipes. All licensees of operating commercial nuclear power
plants in the United States have committed to this initiative as well.
The initiative defined a series of milestones for, among other things,
assessing the condition of buried pipes and establishing a plan for
managing them. Specifically, under this initiative, licensees agreed
to rank their buried piping based on the likelihood and consequences
of its failure and to develop an inspection plan using the results of
the risk ranking, along with other factors, to prioritize the
selection of locations at which they will inspect pipes. The
initiative placed special emphasis on buried piping that is safety-
related and/or contains radioactive material. In 2010, the Buried
Piping Integrity Initiative was expanded to the Buried
Piping/Underground Piping and Tanks Integrity Initiative to address
additional structures. All of the licensees have also committed to
implement the expanded initiative.
Licensees' actions in response to identified leaks at their power
plants have varied, ranging from simply repairing the leak source and
documenting the extent of the leak for future cleanup, to performing
extensive mitigation. Specifically, at six of the seven sites we
visited that had experienced underground piping system leaks, most of
the licensees had identified and repaired the leak source and
conducted remediation and/or monitoring of the groundwater
contamination. For example, when we visited the Vermont Yankee Nuclear
Power Station, the soil near the identified leak source had been
excavated and removed by a radiological waste company hired by the
licensee. In addition, at the Oyster Creek Generating Station in New
Jersey, the licensee had undertaken a mitigation project to excavate
some of its buried piping, either moving the pipes aboveground or
placing them in vaults that can be monitored for leakage.
NRC's response to underground piping leaks has taken various forms.
First, NRC's response to individual leaks has generally been an
increase in oversight at the particular plant, and not issuance of a
violation, because most of the leaks have not posed a safety risk. For
example, after an April 2009 leak at Oyster Creek Generating Station,
NRC sent out regional inspectors to review and evaluate the
circumstances associated with the leak. At other power plants, NRC's
enhanced review has included overseeing some of the groundwater
sampling activities that were performed to characterize leaks. In many
of these instances, NRC relied upon split sampling--sending portions
of some of the groundwater monitoring samples to a laboratory and
comparing its analytical results with those obtained by the licensees'
laboratories for the same samples--to verify the licensees' results.
Furthermore, NRC reviewed its oversight of buried piping and took
actions on the basis of its review. In particular, in the fall of
2009, after several reported leaks from buried piping resulted in
groundwater contamination and increased media coverage, NRC's Chairman
tasked the agency staff with reviewing activities NRC had taken
related to buried pipe leaks. The resulting December 2009 report
concluded that the agency's regulations for the design, inspection,
and maintenance of safety-related buried piping are adequate to ensure
buried piping can perform its safety function.[Footnote 24] The report
also identified a number of ongoing activities, such as conducting
direct visual inspections of piping when a licensee excavates
underground piping for the purpose of repair and replacements. In
2010, NRC developed a Buried Piping Action Plan under which it would
collect a variety of information, including data on buried pipe system
leaks; assess the implementation of the industry's Buried
Piping/Underground Piping and Tanks Integrity Initiative; participate
in reviewing professional codes and standards for buried pipes; and,
if warranted, develop responding regulatory actions.
In 2010, NRC actions also included revising its Aging Management
Program guidance for licensees to manage the effects of aging on
structures or components for license renewal. The revisions include
more detailed and comprehensive guidance for preventing and mitigating
corrosion of underground piping systems and inspecting them. In
addition, NRC proposed requirements for additional groundwater surveys
for decommissioning.
Moreover, in 2010 and 2011, NRC reviewed the extent to which the
industry has implemented the Groundwater Protection Initiative but did
not evaluate its effectiveness. During this review, NRC found that
most plants have implemented most but not necessarily all steps
outlined in the voluntary initiative. To insure full implementation of
the initiative, NRC plans to continue observing the long-term
implementation of this initiative through its Reactor Oversight
Process. However, NRC has no plans to evaluate the extent to which
this initiative, as implemented, will promptly detect leaks and, as a
result, has no assurance that the Groundwater Protection Initiative
will consistently help to promptly detect leaks as nuclear power
plants age. In addition, NRC officials have said they will continue to
review the status of the initiative's implementation, but said that
the agency is not going to incorporate the initiative into its
requirements because of the low level of risk associated with the
reported leaks to date. Therefore, the public cannot be assured the
initiative will remain in place in the future.
In addition, in 2010 NRC convened a Groundwater Task Force composed of
NRC staff to evaluate NRC's actions to address incidents of
groundwater contamination at nuclear power plants and identify actions
for a senior management review group to consider. Later that year, the
task force issued a report that concluded that NRC is accomplishing
its stated mission of protecting the public health and safety and the
environment through its response to leaks and spills that contaminated
groundwater. However, the report also concluded that NRC's response to
leaks and spills has varied widely and that NRC should further
consider ways to communicate more timely and complete information to
the public about these incidents. In early 2011, NRC reported the
results of its senior management's review of the Groundwater Task
Force report findings. This report included four areas in which the
agency committed to action: (1) identifying and addressing policy
issues related to groundwater contamination; (2) enhancing the
agency's Reactor Oversight Process; (3) developing specific actions in
response to key themes and conclusions of the Groundwater Task Force
report; and (4) conducting a focused dialogue with other regulators,
such as EPA and states, to develop a collaborative approach for
enhanced groundwater protection.
Several Stakeholders Recommended That NRC Enhance Its Inspection,
Groundwater Monitoring, and Reporting Requirements:
Several stakeholders noted that NRC should enhance its inspection
requirements for underground piping systems to help prevent leaks. In
addition, several stakeholders suggested that NRC make its groundwater
monitoring requirements more stringent to help detect leaks.
Furthermore, according to some stakeholders, NRC should require more
timely disclosure of information on leaks and make this information
more accessible to the public. The stakeholders we interviewed
included representatives from NRC, other federal and state agencies,
industry and industry groups, standards-setting organizations, and
advocacy and other interested groups, as well as independent
consultants and experts.
Several Stakeholders Identified Enhancements NRC Could Make to Its
Inspection Requirements:
Several of the stakeholders we interviewed said that NRC should
enhance its inspection and testing requirements by requiring that
licensees visually inspect underground piping more frequently and
regularly, inspect piping's structural integrity,[Footnote 25] and
inspect and test nonsafety-related piping that contains radioactive
material. Many stakeholders who recommended more frequent and regular
inspections pointed out that NRC requires direct visual inspection of
underground pipes only when a pipe has been excavated for another
purpose.[Footnote 26] While some stakeholders wanted NRC to require
visual inspections even if that meant licensees would have to excavate
underground piping to do so, one stakeholder pointed out that pipes
can be damaged during excavation and that some pipes may not be
accessible through excavation if, for example, they lie under a road
or building.
In addition, some stakeholders we interviewed recommended that NRC
require inspections of structural integrity of safety-related
underground piping systems, which can be susceptible to corrosion as
plants age. NRC officials and other stakeholders noted that the
pressure and flow tests NRC currently requires do not provide
information about the structural integrity of an underground pipe,
such as whether the pipe has degraded to the point that the thickness
of its wall could hinder the pipe's future performance. One
stakeholder voiced concern that not having structural integrity
information about safety-related underground piping systems could
create a very significant risk to public health and safety if such
pipes were to unexpectedly fail due to corrosion. Moreover, some of
the stakeholders we interviewed noted that some of the inspection
techniques used in the oil and gas industry to provide additional
information about the structural integrity of underground pipes could
be used in the nuclear power industry. However, these stakeholders
recognized that applying such techniques at nuclear power plants may
be difficult, largely because the technology for such tests has not
been sufficiently developed for, or adapted to, the nuclear industry
site conditions. For example, guided wave technology--a method that
transmits ultrasonic energy through a pipe's walls and monitors how
the energy is reflected back to identify areas where a pipe may have
corrosion--is used in the oil and gas industry, which tends to have
miles of relatively straight piping through which waves can travel
with little interference. However, the underground piping at nuclear
power plants tends to include many bends and turns, which can distort
the wave energy and interfere with the inspection test results. In
addition, the oil and gas industry uses robotic devices sent through a
pipe to capture images of its condition and identify areas of
corrosion, but the bends and turns in pipes at nuclear power plants
limit the use of robotic devices by the nuclear power industry.
Although obtaining information about the structural integrity of pipes
is currently challenging, based on stakeholders' observations, NRC and
licensees cannot be assured that underground safety-related pipes
remain structurally sound without having information about degradation
that has occurred. Without such assurance, the likelihood of future
pipe failures cannot be as accurately assessed, and this increases the
uncertainty surrounding the safety of the plants.
Industry and standards-setting organizations have undertaken
activities to address the challenges of inspecting the structural
integrity of underground piping systems at nuclear power plants. For
example, industry, through the Electric Power Research Institute, has
undertaken research to develop new, and improve upon existing,
techniques to provide reliable and usable results, and some licensees
are trying these techniques at their plants. The licensee at the
Seabrook Station, for instance, has plans to pilot test a mechanical
robot that was developed by the Electric Power Research Institute to
detect cracks in underground piping. In addition, stakeholders
representing standards-setting organizations, such as NACE
International and ASME, noted that they have undertaken efforts to
evaluate and enhance current technologies and codes for inspecting
underground piping systems.[Footnote 27] For example, according to a
member of NACE International, the organization formed a buried piping
task group to, among other things, evaluate the current state of
inspection techniques and technologies for underground piping systems
and determine how they could be applied at nuclear power plants.
Moreover, various stakeholders mentioned the need for NRC to require
inspections and testing of nonsafety-related piping that contains
radioactive material. Although NRC currently does not generally
require such inspections,[Footnote 28] nonsafety-related piping has
been the source of many reported leaks that resulted in groundwater
contamination. For example, nonsafety-related piping was the source of
leaks at the Oyster Creek and Braidwood plants. Some stakeholders said
that any system whose failure could result in contamination of the
environment should be prioritized for inspection and testing, even if
it is not classified as being safety-related.
According to NRC stakeholders, NRC has limited ability to enhance the
licensees' inspection requirements of nonsafety-related underground
piping systems, given the low level of risk associated with reported
leaks to date, and the requirement that NRC justify the cost of new
requirements relative to this risk. However, according to industry
stakeholders, the voluntary Buried Piping/Underground Piping and Tanks
Integrity Initiative may address stakeholder concerns related to
inspection of nonsafety-related underground piping that carries
radioactive material. This initiative includes a component under which
licensees assign a risk rank to segments of their underground piping
based on the potential for and consequences of failure. As a result,
systems that are safety-related and systems that contain radioactive
materials receive a higher rank. According to the initiative, systems
with a higher rank will be prioritized for inspection and testing, so
industry stakeholders noted that piping containing radioactive
materials would receive more attention under the initiative.
Several Stakeholders Suggested More Stringent On-site Groundwater
Monitoring Requirements:
Several of the stakeholders we interviewed noted that NRC should have
more stringent requirements for licensees to monitor on-site
groundwater to quickly detect leaks. Industry stakeholders
acknowledged the importance of detecting leaks early to minimize their
consequences. A few stakeholders said they would like to see NRC
require that licensees install groundwater monitoring wells in the
vicinity of potential leaks based on a risk-informed assessment of the
underground piping systems that have the highest likelihood of leaking
and a current and thorough assessment of the site's hydrogeology. Some
stakeholders noted, however, that NRC should allow flexibility for
licensees to determine the best approach to detect leaks at their own
sites and to adapt their approach on the basis of evolving industry
experience.
However, according to stakeholders at NRC, as is the case with
inspection requirements, the agency is unlikely to be able to justify
changing its groundwater monitoring requirements given the low level
of risk associated with reported leaks. Nevertheless, industry and NRC
stakeholders noted that components of the industry's voluntary
Groundwater Protection Initiative may address some stakeholders'
concerns with respect to groundwater monitoring. For example, one of
the objectives of the initiative is to establish an on-site
groundwater monitoring program by considering placing wells closer to
systems with the highest potential for inadvertent releases that could
contaminate groundwater. Moreover, many NRC stakeholders noted that
the industry initiative goes well beyond what the agency can do in
terms of regulations and has already been implemented, whereas
establishing new regulations could take years. In fact, a review
performed by senior managers at NRC concluded that, in view of the
progress being made by industry through the initiative, efforts to
amend NRC's regulations to include the initiative are not necessary at
this time. Moreover, industry stakeholders told us they do not
consider the initiative to be voluntary since all of the power plants'
chief nuclear officers committed to its implementation. Other
stakeholders, however, told us that the language in the initiative is
not strong enough and expressed concern that, because NRC has no
authority to enforce the voluntary initiative, industry could move
away from it at any point without recourse from NRC.
Some Stakeholders Said That NRC Should Require More Timely Leak
Information from Licensees and Should Make It More Accessible to the
Public:
According to some stakeholders, NRC should require licensees to report
information about the level and extent of groundwater contamination
from a leak and the licensee's assessment of a leak's impact in a more
timely manner. One stakeholder noted that the inability to obtain
timely information about leaks could undermine the public's confidence
in NRC and licensee conclusions that a leak does not impact public
health and safety. NRC currently requires licensees to make
information on significant leaks available to the public by providing
groundwater sample results and calculations of the radiation dose the
public has received in its annual radioactive effluent and
environmental reports. Consequently, even though NRC posts on its Web
site some information about leaks as it becomes available, up to a
year may pass between the time a leak occurs and the time the public
receives information supporting the licensee's assessment of the
leaks' impact.
In addition, some stakeholders noted that NRC should make information
pertaining to leaks more accessible to the public. For example, some
of these stakeholders said that NRC could improve the accessibility of
information on its Web site. Specifically, one stakeholder said that
the site is difficult to navigate, cumbersome, and unnecessarily slow.
Another stakeholder noted that staff members at his organization had
used NRC's Web site to track information on groundwater contamination
at a particular site, but the links they used were no longer available.
Conclusions:
The occurrence of leaks at nuclear power plants from underground
piping systems is expected to continue as nuclear power plants age and
their piping systems corrode. While reported underground piping system
leaks to date have not posed discernible health impacts to the public,
there is no guarantee that future leaks' impacts will be the same.
Some of our stakeholders noted that a future leak could put the
public's health and safety at risk if the leak went undetected for a
long period of time. NRC's groundwater monitoring requirements are
intended to identify when the public could be or has been exposed
through drinking water to radiation doses above certain limits rather
than to promptly detect underground piping system leaks. NRC has
concluded that, in general, licensees' groundwater monitoring programs
implemented under the voluntary groundwater initiative go beyond what
the agency requires for groundwater monitoring and could enhance
licensees' prevention of and response to potential leaks by detecting
them early. However, without regularly evaluating the extent to which
the initiative will result in prompt detection of leaks, NRC cannot be
assured that groundwater monitoring programs under the initiative will
detect leaks before they pose a risk to public health and safety.
In addition, although NRC has acknowledged that the corrosion of
underground piping systems, particularly those that are safety-
related, is a concern, limitations in the industry's ability to
measure the wall thickness of an underground pipe without excavation
prevent licensees from determining the structural integrity of
underground piping systems. Without being able to identify that an
underground piping system's structural integrity has not been
compromised by corrosion, the risk to public health and safety is
increased. In this context, licensees at nuclear power plants cannot
assure that a safety-related pipe will continue to function properly
between inspection intervals, thereby protecting the public's health
and safety.
Recommendations for Executive Action:
To ensure the continued protection of the public's health and safety,
we recommend that the Chairman of NRC direct agency staff to take the
following two actions:
* Periodically evaluate the extent to which the industry's voluntary
Groundwater Protection Initiative will result in prompt detection of
leaks and, based upon these evaluations, determine whether the agency
should expand its groundwater monitoring requirements.
* Stay abreast of ongoing industry research to develop technologies
for structural integrity tests and, when they become feasible, analyze
costs to licensees of implementing these tests compared with the
likely benefits to public health and safety. Based on this analysis,
NRC should determine whether it should expand licensees' inspection
requirements to include structural integrity tests for safety-related
underground piping.
Agency Comments and Our Evaluation:
We provided a draft of this report to NRC for its review and comment.
NRC provided written comments, which are reproduced in appendix III,
and technical comments, which we incorporated into the report as
appropriate. NRC agreed with the information presented in the draft
report and said they believe it to be fair and balanced. NRC also
agreed with each of the report recommendations and asserted that they
have established activities to address the recommendations.
In responding to our recommendation to periodically evaluate the
extent to which the industry voluntary Groundwater Protection
Initiative will result in prompt detection of leaks and, based on
these evaluations, determine whether the agency should expand its
groundwater monitoring requirements, NRC stated that "the public can
be assured that the NRC will continue to review the status of industry
implementation of the initiative and consider regulatory changes as
appropriate." Specifically, NRC said that it reviews reported
groundwater monitoring results and changes to licensees' programs for
identifying and controlling spills and leaks. However, as we reported,
the agency has not assessed the adequacy of the licensees' groundwater
monitoring programs, which were implemented under the Groundwater
Protection Initiative, to promptly detect leaks. Absent such an
assessment, we continue to believe that NRC has no assurance that the
Groundwater Protection Initiative will lead to prompt detection of
underground piping system leaks as nuclear power plants age.
In addition, NRC agreed with our recommendation that it stay abreast
of ongoing research on structural integrity tests; analyze the costs
and benefits of implementing feasible tests; and, on the basis of this
analysis, determine whether it should require structural integrity
tests for safety-related piping. Further, NRC pointed out that it has
established milestones to periodically assess both the performance of
available inspection technology and the need to make changes to the
current regulatory framework. Nevertheless, NRC said it "believes
there is reasonable assurance that the underground piping systems will
remain structurally sound." We believe that structural integrity
tests, when feasible, would provide enhanced assurance of underground
piping systems' structural soundness and enable more proactive
oversight. As we reported, NRC's currently required pipe testing
procedures--which provide information about a pipe's function at a
particular point in time--do not indicate the presence of degradation
in a pipe that could hinder its future performance.
As agreed with your offices, unless you publicly announce the contents
of this report earlier, we plan no further distribution until 30 days
from the report date. At that time, we will send copies to the
appropriate congressional committees, Chairman of NRC, and other
interested parties. In addition, this report will be available at no
charge on the GAO Web site at [hyperlink, http://www.gao.gov].
If you or your staff members have any questions about this report,
please contact me at (202) 512-3841 or ruscof@gao.gov. Contact points
for our Offices of Congressional Relations and Public Affairs may be
found on the last page of this report. Key contributors to this report
are listed in appendix IV.
Signed by:
Frank Rusco:
Director, Natural Resources and Environment:
[End of section]
Appendix I: Objectives, Scope, and Methodology:
Our objectives were to (1) determine experts' opinions on the impacts,
if any, that underground piping system leaks have had on public health
and the environment; (2) assess Nuclear Regulatory Commission (NRC)
requirements of licensees for inspecting underground piping systems
and monitoring and reporting on leaks from these systems; (3) identify
actions the nuclear power industry, licensees, and NRC have taken in
response to underground piping system leaks; and (4) identify,
according to key stakeholders, what additional NRC requirements, if
any, could help prevent, detect, and disclose leaks from underground
piping systems.
To determine experts' opinions on the impacts that underground piping
system leaks have had on public health and the environment, we worked
with the National Academy of Sciences to organize two half-day expert
group discussion sessions in January 2011 to discuss (1) issues
related to the public health risks associated with radioactive leaks
from underground piping systems at nuclear power plants and (2) the
environmental resource impacts from the leaks. In addition, we held a
half-day plenary discussion session to follow up on questions left
open during the public health impacts and environmental impacts group
discussion and to discuss the overall characterization of impacts from
leaks.
In discussing the public health and environmental impacts of leaks, we
asked the experts to consider three case studies of nuclear power
plants that have experienced leaks from underground piping systems
including Braidwood Generating Station in Illinois, Oyster Creek
Generating Station in New Jersey, and Vermont Yankee Nuclear Power
Station in Vermont. We compiled information packets on each of the
case studies using sources such as NRC inspection reports, licensee
environmental and effluent reports, Environmental Impact Statements
prepared for license renewal, licensee hydrogeology reports, and
licensee groundwater monitoring results and maps (see appendix II).
The panelists were provided the information packets prior to the panel
sessions. We selected these case studies because they included power
plants that:
* had among the highest detected on-site groundwater tritium
concentrations that were associated with underground piping system
leaks,
* received a significant amount of publicity surrounding underground
piping system leaks, and:
* had contaminants from leaks that migrated off-site.
The case studies selected had a range of cooling water sources,
included both boiling water reactors and pressurized water reactors,
and represented a range of plant ages with start of operations dates
from 1969 to 1988.
For the first discussion group on public health impacts from
underground piping system leaks, the National Academy of Sciences
invited qualified individuals with expertise in toxicology, health
physics, public health, risk assessment, dosimetry, nuclear
engineering, regulatory issues, and radiobiology. For the second
discussion group on the environmental impacts of underground piping
system leaks, the National Academy of Sciences invited individuals
with expertise in the environmental effects of radiation, fate and
transport of radioactive materials, civil engineering, water quality
and remediation, hydrogeology, risk assessment, nuclear engineering,
and regulatory issues. The invited experts had experience working in
academia, consulting, and the federal government. None of the experts
were compensated for their work on the discussion groups, and all
experts were screened by the National Academy of Sciences for
potential conflicts of interest. The following experts participated in
the discussion sessions:
Discussion Group on Public Health Impacts:
* Jerome Puskin, U.S. Environmental Protection Agency:
* Phaedra S. Corso, University of Georgia:
* Chris G. Whipple, ENVIRON Corporation:
* Lynn R. Anspaugh, University of Utah:
* Carl Paperiello, Talisman International, LLC:
* David Brenner, Columbia University:
Discussion Group on Environmental Impacts:
* Timothy Mousseau, University of South Carolina:
* Patricia J. Culligan, Columbia University:
* James Clarke, Vanderbilt University:
* John Quinn, Argonne National Laboratory:
* Chris G. Whipple, ENVIRON Corporation:
* Carl Paperiello, Talisman International, LLC:
To assess the requirements that NRC places on licensees for inspecting
underground piping systems and monitoring and reporting on leaks from
these systems, we reviewed and analyzed relevant NRC regulations and
requirements, and interviewed NRC officials from the Office of Nuclear
Reactor Regulation, Office of General Counsel, Region I, and Region
III (a map of the NRC regions is provided in figure 3).
Figure 3: NRC Regional Offices:
[Refer to PDF for image: illustrated U.S. map]
The following are depicted on the map:
Headquarters: Rockville, Maryland.
Region I:
Regional Office: King of Prussia, Pennsylvania.
Region II:
Regional Office: Atlanta, Georgia.
Region III:
Regional Office: Lisle, Illinois.
Region IV:
Regional Office: Arlington, Texas.
Sources: NRC (data); Map Resources (map).
[End of figure]
To identify actions the nuclear power industry, licensees, and NRC
have taken in response to underground piping system leaks, we
conducted site visits at a nonprobability sample[Footnote 29] of seven
nuclear power plants in NRC Regions I and III, which are listed in
table 2. During the site visits, we interviewed industry officials and
NRC resident inspectors and observed ongoing underground piping system
mitigation activities. We selected nuclear power plants for their site
visits to include plants that had experienced recent reported
underground piping system leaks and a nuclear power plant that had not
experienced a major reported leak.
Table 2: Nuclear Power Plant Site Visits:
Nuclear power plant: Braidwood Station;
State: Illinois;
NRC Region: III.
Nuclear power plant: Dresden Nuclear Power Station;
State: Illinois;
NRC Region: III.
Nuclear power plant: Indian Point Nuclear Generating Station;
State: New York;
NRC Region: I.
Nuclear power plant: Oyster Creek Nuclear Generating Station;
State: New Jersey;
NRC Region: I.
Nuclear power plant: Pilgrim Nuclear Power Station;
State: Massachusetts;
NRC Region: I.
Nuclear power plant: Seabrook Station;
State: New Hampshire;
NRC Region: I.
Nuclear power plant: Vermont Yankee Nuclear Power Station;
State: Vermont;
NRC Region: I.
Source: GAO.
[End of table]
In addition, we gathered and reviewed relevant documents from NRC,
including NRC task force reports, policy papers, and an action plan;
and industry, including documentation of industry initiatives.
Finally, to determine, according to key stakeholders, what additional
NRC requirements, if any, could help prevent and detect leaks from
underground piping systems, we identified and interviewed over 30 key
stakeholders using a standard set of questions. To ensure a balanced
range of perspectives, we selected stakeholders from the following
organizations:
* independent consultants and experts;
* advocacy and other interested groups, including Beyond Nuclear,
Riverkeeper, Pilgrim Watch, and Union of Concerned Scientists;
* industry and industry groups, including licensees at the nuclear
power plants that we visited, the Nuclear Energy Institute, and the
Electric Power Research Institute;
* standards-setting organizations, including the American Society of
Mechanical Engineers, and NACE International;
* NRC, including officials from Headquarters, Region I, and Region III;
* other federal and state agencies that have worked on issues related
to underground piping system leaks and associated groundwater
contamination.
We identified stakeholders by performing an Internet and literature
search for individuals and organizations that have published relevant
reports and studies and by asking previously identified stakeholders
for referrals.
[End of section]
Appendix II: Case Studies for Experts' Consideration:
We worked with the National Academy of Sciences to convene groups of
experts to discuss the impacts that underground piping system leaks
have had on public health and the environment. We asked the experts to
consider these impacts in the context of three case studies of nuclear
power plants that recently experienced leaks from underground piping
systems. Prior to the January 2011 discussion groups, the National
Academy of Sciences sent the experts information packets that we
prepared using NRC and licensee reports to provide background
information on these three case studies. This appendix contains
excerpts of these case study information packets, excluding their
attachments.
Case Study Introduction:
We and the National Academy of Sciences are convening expert
discussion groups on (1) the public health risks resulting from
underground piping system leaks at nuclear power plants and (2) the
environmental impacts resulting from underground piping system leaks
at nuclear power plants and a plenary session on the overall
characterization of leak impacts and further information needs. We
would like to obtain the following information from each of the
discussion groups:
Public Health Risks Discussion Group:
Information desired:
* the impacts to public health from selected leak case studies, and:
* the potential impacts to public health if everything in the case
study remained the same, but the tritium concentrations were higher.
Proposed questions for the experts:
1. What is the risk (or risk range) associated with the levels of
tritium detected in groundwater at select nuclear power plants if the
groundwater was to be used for drinking water (see attached case study
information packets)? Please describe the assumptions used and the
sensitivity of the risk to these assumptions.
2. How would the risk change if the tritium concentrations were twice
the maximum concentration listed above? How would they change if the
concentrations were an order of magnitude greater?
3. What additional exposure pathways (other than groundwater) could
impact the overall health risk posed to the public by tritium and
other radionuclides released into the environment from the leaks
(e.g., Cesium-137, Strontium-90)?
Environmental Resource Impacts Discussion Group:
Information desired:
* the impacts on environmental resources from select leak case
studies, and:
* the potential impacts to environmental resources if everything in
the case studies remained the same, but the tritium concentrations
were higher.
Proposed questions for the experts:
1. To what extent have selected leaks from nuclear power plants
degraded environmental resources, both on-site and off-site, in a
manner that compromises their quality or limits their present or
future value or use (see attached case study information packets)?
2. How would the environmental resource impacts change if the
contaminant concentrations were twice the concentrations in the
examples above? How would they change if the concentrations were an
order of magnitude greater?
3. If leaks of similar magnitudes were to occur at other plants, what
factors might affect the extent of the resultant environmental impacts
or make a particular site more vulnerable to impacts?
Plenary:
Information desired:
* the overall characterization of public health and environmental
impacts from leaks, including considerations for cumulative and long-
term impacts,
* ability to fully characterize impacts based on the information
available from NRC, and:
* the additional information that would be required to fully
characterize and assess impacts to public health and environmental
resources.
We selected three case study nuclear power plants for the experts'
consideration: Braidwood, Oyster Creek, and Vermont Yankee. Each of
these plants has had a recent underground piping system leak that
generated public interest. In addition, the case studies represent
some of the highest groundwater tritium concentrations detected at
nuclear power plants in association with underground piping system
leaks. Summary information about each of the case studies is presented
in table 3.
Table 3: Summary of Underground Piping System Leak Case Studies:
Nuclear power plant (state): Braidwood (IL);
Reactor type: PWR;
Year operations began: 1988;
Maximum detected/reported on-site groundwater tritium concentration:
282,000 pCi/L;
Maximum detected/reported off-site groundwater tritium concentration:
1,600 pCi/L.
Nuclear power plant (state): Oyster Creek (NJ);
Reactor type: BWR;
Year operations began: 1969;
Maximum detected/reported on-site groundwater tritium concentration:
4,500,000 pCi/L;
Maximum detected/reported off-site groundwater tritium concentration:
None.
Nuclear power plant (state): Vermont Yankee (VT);
Reactor type: BWR;
Year operations began: 1972;
Maximum detected/reported on-site groundwater tritium concentration:
2,500,000 pCi/L;
Maximum detected/reported off-site groundwater tritium concentration:
None.
Legend: BWR = Boiling Water Reactor; PWR = Pressurized Water Reactor:
Source: GAO table based on NRC data.
[End of table]
For each of the case studies, we compiled case study information
packets for the panelists that include information on the case study
nuclear power plant location and area demographics; a description of
the environment near the plant; and information about each of the
radioactive leaks, including groundwater tritium concentrations and
dose assessment results.
Case Study 1: Braidwood Generating Station:
The following information was compiled from NRC reports, licensee-
prepared reports to NRC, and Exelon's "Tritium Project" Web site.
Site Location and Demographics:
Braidwood Generating Station (see figure 4)--which consists of two
pressurized water reactors owned and operated by Exelon Nuclear--is
located in Braceville, Illinois, and covers approximately 4,457 acres
of land with a 2,537-acre cooling lake. More broadly, the site is
situated in Will County, Illinois, about 20 miles southwest of Joliet,
Illinois, and 60 miles southwest of Chicago. In 2009, approximately
685,000 people resided in Will County's 837 square miles, resulting in
density of 600 persons/square mile.
Figure 4: Braidwood Generating Station:
[Refer to PDF for image: photograph]
Source: NRC.
Note: This photograph was not included in the information packet sent
to the experts.
[End of figure]
Description of the Environment near Braidwood Station:
Attachment A,[Footnote 30] which is an excerpt from a hydrogeologic
investigation report for Braidwood, includes a description of the
environment near Braidwood including topography, surface water
features, geology, hydrogeology, and groundwater flow conditions in
the region surrounding the station.
Surrounding Land Use:
Land surrounding the Braidwood site falls mainly into the
agricultural, residential, and recreational use categories.
Residential lots surround the site to the north and to the east along
Smiley Road and Center Street. Further to the north, there are several
ponds or small lakes. The center of the Village of Braidwood is
approximately 8,000 feet from the site measured from Smiley Road. To
the northwest of the site, there are two main highways (Illinois State
Highway 53 and Illinois Route 129) running parallel to each other with
a railroad (Southern Pacific Railroad) between them. Within the
southern portion of the site is the Cooling Lake that is used as a
recreational area in the summer for boating and fishing by the
Illinois Department of Natural Resources.
A Land Use Survey conducted during August 2005 around the Braidwood
Station was performed by Environmental Inc. (Midwest Labs) for Exelon
Nuclear to comply with Braidwood Station's Offsite Dose Calculation
Manual. The purpose of the survey was to document the nearest
resident, milk producing animal and garden of greater than 500 ft2 in
each of the sixteen 22½ degree sectors around the site. The results of
this survey are summarized in table 4.
Table 4: Braidwood Land Use Survey Results:
Distance in miles from the Braidwood Station reactor buildings:
Sector: N;
Residence miles: 0.5;
Livestock miles: 2.6;
Milk farm miles: None.
Sector: NNE;
Residence miles: 1.8;
Livestock miles: None;
Milk farm miles: None.
Sector: NE;
Residence miles: 0.7;
Livestock miles: 0.9;
Milk farm miles: None.
Sector: ENE;
Residence miles: 0.8;
Livestock miles: 3.3;
Milk farm miles: None.
Sector: E;
Residence miles: 0.8;
Livestock miles: 2.3;
Milk farm miles: None.
Sector: ESE;
Residence miles: 2.2;
Livestock miles: 2.3;
Milk farm miles: None.
Sector: SE;
Residence miles: 2.7;
Livestock miles: 2.7;
Milk farm miles: 11.2.
Sector: SSE;
Residence miles: 4.5;
Livestock miles: 4.1;
Milk farm miles: None.
Sector: S;
Residence miles: 4.2;
Livestock miles: 4.8;
Milk farm miles: None.
Sector: SSW;
Residence miles: 1.3;
Livestock miles: 5.3;
Milk farm miles: 5.6.
Sector: SW;
Residence miles: 0.4;
Livestock miles: 1.2;
Milk farm miles: None.
Sector: WSW;
Residence miles: 0.5;
Livestock miles: 3.8;
Milk farm miles: None.
Sector: W;
Residence miles: 0.4;
Livestock miles: 1.6;
Milk farm miles: 8.7.
Sector: WNW;
Residence miles: 0.4;
Livestock miles: 5.4;
Milk farm miles: None.
Sector: NW;
Residence miles: 0.4;
Livestock miles: None;
Milk farm miles: None.
Sector: NNW;
Residence miles: 0.4;
Livestock miles: None;
Milk farm miles: None.
Source: Exelon (from NRC).
[End of table]
Underground Piping System Leaks:
During March 2005, the licensee was notified by the Illinois
Environmental Protection Agency of reports of tritium in wells in a
nearby community. Following that notification, the licensee began
monitoring groundwater between the community and Braidwood Station and
obtained samples from a drainage ditch that was near the community.
While no contaminated groundwater was identified, the licensee did
measure levels of tritium in the drainage ditch near the Braidwood
access road. The licensee performed additional monitoring to identify
the source of that tritium contamination.
Between March 2005 and March 2006, the licensee sampled the wells of
several homeowners with drinking water wells and installed groundwater
monitoring wells to determine the extent of the tritium contamination.
On November 30, 2005, the NRC Region III office was notified that the
licensee had measured tritium levels as high as 58,000 picocuries per
liter (pCi/L) in shallow, groundwater monitoring wells located at the
northern edge of the owner-controlled area.
The licensee attributed the contamination to historical leakage of
vacuum breakers along the circulating water blowdown line that is
routinely used for radioactive liquid releases to the Kankakee River.
As an immediate corrective action, the licensee suspended all further
releases of liquid radioactive material, while the licensee performed
a more comprehensive evaluation of the incidents.
Beginning in December 2005, the NRC performed an independent analysis
of split samples taken from some of the licensee's monitoring wells
and collected independent samples from some residents nearest to the
site boundary. The NRC sample results were consistent with the
licensee's results.
The licensee identified tritium levels between 1,400 and 1,600 pCi/L
in one residential drinking water well. The tritium levels detected in
that well were below the Environmental Protection Agency (EPA)
drinking water standard of 20,000 pCi/L. The tritium levels also
corresponded to calculated doses that are well below the corresponding
NRC dose limits. The remaining residential well samples had no
measurable tritium above normal background levels. However, the
licensee's monitoring identified an area of contaminated groundwater
that extended about 2,000 to 2,500 feet north of the site boundary.
Initial measurements by the licensee and independent measurements by
the NRC confirmed that gamma-emitting radionuclides and Strontium-90
(Sr-90) were not detected in the contaminated groundwater.
NRC inspectors reviewed the origin of the tritium contamination with
the licensee's staff. Based on the information presented and the
licensee's measurements, the inspectors confirmed that the measured
levels of tritium in the environment were consistent with past leakage
of the vacuum breakers on the circulating water blowdown line. That
line normally carried nonradioactive water back to the Kankakee River
but also served as a dilution pathway for planned liquid radioactive
releases. The line was about 5 miles long and contained 11 vacuum
breakers that compensated for pressure transients within the line from
liquid surges. A map of the blowdown line is included in Attachment B.
[Footnote 31]
The licensee's investigation identified that significant unplanned
radioactive releases from three of these vacuum breakers during 1996,
1998, and 2000 and other minor releases between 1996 and 2005 entered
the groundwater system. The 1996 event resulted in the leakage of an
estimated 250,000 gallons of water. The 1998 and 2000 events each
resulted in a leakage of an estimated 3,000,000 gallons of water. Each
leak from a vacuum breaker occurred over a period coincident with
ongoing, liquid radioactive releases through the blowdown line. NRC
inspectors reviewed the licensee's effluent release documents for the
time periods described above and confirmed that the intended releases
would have met NRC requirements if the releases had been made to the
Kankakee River.
The inspectors reviewed the licensee's radiological monitoring and
assessments performed during March 2005 through March 2006, to
characterize the extent of groundwater contamination from blowdown
line vacuum breaker leakage. Specifically, the inspectors reviewed:
(1) the licensee's characterization report, which documented the local
hydrogeology around the facility through the installation of
groundwater monitoring wells on licensee-owned property around the
blowdown line; (2) the licensee's sampling and analysis program, which
included groundwater and drinking water samples from private wells
near the blowdown line; and (3) the licensee's evaluation of blowdown
line integrity, which included acoustical monitoring of the line. The
inspectors compared the licensee's results to the independent analysis
performed by the NRC's contract laboratory to evaluate the accuracy of
the licensee's measurements (see Attachment C).[Footnote 32]
NRC inspectors independently estimated the extent and magnitude of the
groundwater tritium contamination through NRC's contract analysis of
water samples collected from residential drinking wells near the
facility and from shallow monitoring wells installed by the licensee.
The NRC's contract laboratory analyzed the samples for tritium
contamination. In addition, the NRC's contract laboratory analyzed
selected samples for other radionuclides using gamma spectroscopy, and
analyses have also been performed for Sr-90 and Technetium-99 (Tc-99).
The contract laboratory also utilized special techniques to identify
"difficult to detect" radionuclides, such as Iron-55 (Fe-55), Nickel-
63 (Ni-63), and transuranic elements.
The NRC's results confirmed that tritium was present in one off-site
residential well at levels of about 1,300 to 1,500 pCi/L, which is a
small fraction of the EPA drinking water standard of 20,000 pCi/L. In
all other residential wells, no measurable levels of tritium or other
licensed radioactive material above normal background have been
detected. In a deeper on-site groundwater well, the NRC measured
tritium as high as 282,000 pCi/L. Measurable levels of tritium have
been found off-site in shallow monitoring wells and in a pond located
near the plant boundary (see Attachment B).
Estimated Off-site Radiation Doses:
Exelon released a report in March 2006 that assessed the potential off-
site radiation doses that could have been received by members of the
public from exposure to tritium that reached the off-site environment
around the Braidwood Station following the blowdown line releases. The
following paragraphs summarize the results of this study, which is
included in its entirety in Attachment D.[Footnote 33]
Conservative exposure scenarios were evaluated to develop bounding
dose estimates--the highest reasonable radiation doses that could have
been received by members of the public. These conservative scenarios
were then evaluated in more detail to develop realistic estimates of
dose. The methodology of NRC Regulatory Guide 1.109 was used as the
basis for estimating doses from all scenarios.
The estimated bounding dose to a member of the public was about 0.16
millirem per year (mrem/yr) from ingestion of drinking water from a
residential groundwater well containing tritium from a vacuum breaker
release. The highest realistic estimates of radiation dose were from
the same drinking water scenario. The estimated maximum realistic dose
was 0.068 mrem/yr with an average or expected value about one-half
that or 0.034 mrem/yr. When doses from the realistic exposure
scenarios were summed, the maximum dose was estimated to be 0.072
mrem/yr. Table 5 lists these dose estimates.
The estimated doses from the vacuum breaker releases at the Braidwood
Station are well below the design objective of 6 mrem/yr for the two-
unit site provided in Title 10 of the Code of Federal Regulations Part
50 (10 C.F.R. 50, Appendix I). The doses are even further below the
100 mrem/yr regulatory dose limit for a member of the public provided
in 10 C.F.R. 20, Subpart D. The estimated radiation dose represents a
negligible increased risk--less than 0.1 percent of the risk from
natural background radiation--to members of the public.
Table 5: Doses to the Public from Vacuum Breaker Releases (mrem/yr):
Exposure scenario: Drinking well water (2 adults);
Minimum: ~0;
Average (expected): 0.034[A];
Maximum: 0.068[B].
Exposure scenario: Eating fish from Exelon Pond (multiple individuals);
Minimum: 0;
Average (expected): 0.0011;
Maximum: 0.0034.
Exposure scenario: Maximum individual summed dose;
Minimum: ~0;
Average (expected):
