Information Notice 2012-05, Abnormal Releases of Radioactive Water Potentially Resulting in Groundwater Contamination
| ML120410213 | |
| Person / Time | |
|---|---|
| Issue date: | 04/25/2012 |
| From: | Mcginty T Division of Policy and Rulemaking |
| To: | |
| Beaulieu, D P, NRR/DPR, 415-3243 | |
| References | |
| TAC ME7178 IN-12-005 | |
| Download: ML120410213 (8) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
OFFICE OF FEDERAL AND STATE MATERIALS AND
ENVIRONMENTAL MANAGEMENT PROGRAMS
WASHINGTON, DC 20555-0001 April 25, 2012 NRC INFORMATION NOTICE 2012-05: ABNORMAL RELEASES OF RADIOACTIVE
MATERIAL IN LIQUIDS POTENTIALLY
RESULTING IN GROUNDWATER
CONTAMINATION
ADDRESSEES
All holders of an operating license or construction permit for a nuclear power reactor or a
non-power (research or test) reactor under Title 10 of the Code of Federal Regulations
(10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities, including those
who have permanently ceased operations and have spent fuel in storage in the spent fuel pool.
All Agreement State Radiation Control Program Directors and State Liaison Officers.
PURPOSE
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform
addressees of the sources and causes of recent abnormal, unmonitored releases of radioactive
materials in liquids to the ground that could potentially migrate to groundwater. The IN
summarizes some examples of recent abnormal releases, and identifies those plant systems
and causes most frequently associated with these abnormal releases. Industry programs are
providing more active management of situations to minimize unplanned releases. NRC staff
plans to continue to assess the effectiveness of the programs through the Reactor Oversight
Process. Licensees are reminded to remain vigilant and maintain their operations and designs
consistent with their licensing basis to minimize unplanned releases. The NRC expects that
recipients will review the information for applicability to their facilities and consider actions, as
appropriate, to avoid similar problems. Suggestions contained in this IN are not NRC
requirements; therefore, no specific action or written response is required.
BACKGROUND
Nuclear power plants and non-power reactors routinely and safely discharge liquids that have
dilute concentrations of radioactive materials. Licensees monitor these authorized discharges
and report them to the NRC. Power reactors submit annual effluent reports that are posted on
the NRCs Web site at: http://www.nrc.gov/reactors/operating/ops-experience/tritium/plant- info.html.
However, as with any industrial facility, a nuclear power plant or non-power reactor may deviate
from normal operation with an abnormal release (e.g., leaks and spills) of radioactive material in
liquids (e.g., tritium in water) to the on-site environment. Abnormal liquid releases onto the
ground surface can be absorbed into the subsurface and reach the local water table, depending
on the local subsurface characteristics, soil properties, and associated liquid flux of the release.
The dispersion of the leaked or spilled water depends on the local subsurface geology and
hydrogeologic characteristics. Contaminants such as tritium will be transported in the
subsurface as a function of groundwater flow processes and conditions (e.g., hydraulic
gradients, permeability, porosity, and geochemical processes) and may eventually be
discharged to the unrestricted area.
Nuclear power plants use site conceptual models based on hydrogeological models and data
from on-site ground water monitoring wells to predict the subsurface water flow to include the
flow direction and flow rate to be used as the monitoring basis for estimating the amount of
radioactive material discharged into the unrestricted area. Because of the low concentrations of
radioactive material in liquids, non-power reactors generally do not have water monitoring wells
or site conceptual models.
If an abnormal, unmonitored release occurs at a nuclear power plant, the NRC resident
inspector and regional specialists assess the licensees response to ensure that NRC
requirements are met. Nuclear power plant licensees submit reports of abnormal, unmonitored
releases in the annual radioactive effluent reports as described above. For abnormal releases, the reports provide information such as the date and duration, location, volume, estimated
activity of each radionuclide, effluent monitoring results, on-site monitoring results, depth to the
local water table, classification(s) of subsurface aquifer(s), size and extent of any ground water
plume, expected movement/mobility of any ground water plume, land use characteristics (e.g.,
water used for irrigation), remedial actions considered or taken and results obtained, calculated
dose to a member of the public that is attributable to the discharge, and actions taken to prevent
recurrence.
For non-power reactors, NRC inspectors from the Research and Test Reactors Oversight
Branch would assess the licensees response to an abnormal unmonitored release. Non-power
reactors submit information on normal releases to the environment in their annual reports to
NRC. Abnormal, unmonitored releases are normally reported to the NRC as events in
accordance with the facility technical specifications.
NRC Regulatory Guide 1.21, Rev. 2, Measuring, Evaluating, and Reporting Radioactive
Material in Liquid And Gaseous Effluents and Solid Waste, issued in June 2009, and NRC
Regulatory Guide 4.1, Rev. 2, issued in June 2009, Radiological Environmental Monitoring for
Nuclear Power Plants, provides additional information and are available on the NRCs public
Web site (Agencywide Documents Access and Management System (ADAMS) Accession Nos.
ML091170109 and ML091310141, respectively).
Related NRC Requirements
NRC requirements related to radioactive liquid effluents include:
- 10 CFR 20.1301(a)(1) requires each licensee to conduct operations so that the total
effective dose equivalent to individual members of the public from the licensed operation
does not exceed 100 millirems (1 millisievert) in a year.
- 10 CFR 20.1302, Compliance with Dose Limits for Individual Members of the Public, requires licensees to perform appropriate surveys in unrestricted and controlled areas to
demonstrate compliance with dose limits for individual members of the public.
- 10 CFR 20.1406, Minimization of Contamination, was amended in 2011 to add
paragraph (c) [Effective date: December 17, 2012], which requires licensees, to the
extent practical, to conduct operations to minimize the introduction of residual
radioactivity into the site, including the subsurface.
- 10 CFR 20.1501, General, requires licensees, in part, to conduct surveys that may be
necessary to comply with 10 CFR Part 20, Standards for Protection Against Radiation, and are reasonable under the circumstances to evaluate the magnitude and extent of
radiation levels, the concentrations or quantities of radioactive material, and the potential
radiological hazards.
- 10 CFR Part 50, Appendix I, Numerical Guides for Design Objectives and Limiting
Conditions for Operation to Meet the Criterion As Low as is Reasonably Achievable for
Radioactive Material in Light-Water-Cooled Nuclear Power Reactor Effluents, establishes design objectives for equipment installed to maintain control over radioactive
liquid effluents. One design objective is that the calculated annual total quantity of all
radioactive material above background discharged to unrestricted areas will not result in
an estimated annual dose or dose commitment from liquid effluents in excess of
3 millirems to the total body or 10 millirems to any organ. [Appendix I to 10 CFR Part 50
is not applicable to non-power reactors.]
- Criterion 64, Monitoring Radioactivity Releases, of Appendix A, General Design
Criteria for Nuclear Power Plants, to 10 CFR Part 50 requires, in part, a means for
monitoring effluent discharge paths and the plant environs for radioactivity that may be
released from normal operations. NRC Regulatory Issue Summary 2002-02, Lessons
Learned Related to Recently Submitted Decommissioning Plans and License
Termination Plans, dated January 16, 2002, provides additional information (ADAMS
Accession No. ML013510432). [Criterion 64 of Appendix A to 10 CFR Part 50 is not
applicable to non-power reactors.]
- 10 CFR 50.75(g)(1) requires, in part, that each licensee keep a record of spills or other
unusual occurrences involving the spread of contamination in and around the facility or
site. These records must include any known information on identification of involved
nuclides, quantities, forms, and concentrations. (Note: Such documentation in a
decommissioning record file is important to provide a database for site characterization
during decommissioning and for providing support for public and worker dose
assessments. NUREG-1757, Consolidated NMSS (Office of Nuclear Material Safety
and Safeguards) Decommissioning Guidance, issued September 2003, provides
guidance on decommissioning recordkeeping (ADAMS Accession No. ML032530410).
- 10 CFR 50.72, Immediate Notification Requirements for Operating Nuclear Power
Reactors, requires a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> report to the NRC Operations Center when any event or
situation occurs related to protection of the environment for which a news release or
notification to other government agencies has been or will be made. [10 CFR 50.72 is
not applicable to non-power reactors.] Related NRC Generic Communications
- NRC IN 2006-13, Ground-Water Contamination Due to Undetected Leakage of
Radioactive Water, dated July 10, 2006 (ADAMS Accession No. ML060540038)
- NRC IN 2004-05, Spent Fuel Pool Leakage to Onsite Ground Water, dated
March 3, 2004 (ADAMS Accession No. ML040580454)
- NRC RIS 2008-03, Return/Re-use of Previously Discharged Radioactive Effluents, dated February 13, 2008 (ADAMS Accession No. ML072120368)
DESCRIPTION OF CIRCUMSTANCES
For each of the following circumstances, the NRC reviewed the licensees corrective actions for
the abnormal releases and verified licensee analyses showing that no public dose limits or
license conditions that limit radioactive material releases have been, or are expected to be, exceeded.
Oyster Creek Nuclear Generating Station
On August 25, 2009, while excavating a buried aluminum condensate transfer pipe to determine
if it was leaking tritiated water into the soil, the licensee at Oyster Creek Nuclear Generating
Station discovered a condensate leak of 8 gallons to 12 gallons per minute with a tritium
concentration of approximately 10 million picocuries per liter. The licensee replaced the
condensate transfer piping that was leaking. This event is described in Oyster Creek
Generating StationNRC Integrated Inspection Report 05000219/2009005, dated
January 26, 2010 (ADAMS Accession No. ML100260020).
Dresden Nuclear Power Station
The licensee for Dresden Nuclear Power Station collected samples from June 2-6, 2009, and
identified tritium concentrations of 3.2 million picocuries per liter from an onsite groundwater
testing well. The licensee found that two underground condensate transfer pipes were leaking
water containing tritium. The leak was stopped when the leaking pipe was isolated and drained.
This event is described in Dresden Nuclear Power Station, Units 2 and 3 Integrated Inspection
Report 05000237/2009-004; 05000249/2009-004, dated November 6, 2009 (ADAMS Accession
No. ML093100592).
Edwin I. Hatch Nuclear Plant
On September 28, 2011, the results of the groundwater samples taken from two onsite
monitoring wells indicated that there were elevated levels of tritium in the vicinity of the Unit 1 condensate storage tank. It was determined that the initial concentration of tritium was 5.34 million picocuries per liter and is confined to the condensate storage tank area. Currently, there
is no evidence that the tritium has migrated outside of the area of the two sample points. The
source of the tritium was identified as a condensate transfer line and use of the transfer piping
was immediately terminated. No radionuclides other than tritium were detected in the
groundwater samples. The affected groundwater is located in an isolated perched aquifer that
is not utilized for drinking water, and does not have the potential to be used for drinking water. Tritium concentrations have decreased since discovery as a result of eliminating the source of
tritium and by extracting water from the monitoring wells.
This event is discussed in Edwin I. Hatch Nuclear PlantNRC Integrated Inspection
Report 05000321/2011004 and 05000366/2011004, dated October 28, 2011 (ADAMS
Accession No. ML113010464).
LaSalle County Station
On July 1, 2010, NRC resident inspectors were informed of elevated levels of tritium around the
two condensate storage tanks. Samples were taken from an onsite monitoring well adjacent to
the Unit 1 tank and it was determined that the tritium concentration was 700,000 picocuries per
liter. Upon inspection, the licensee identified leakage through three small holes on the bottom
of the Unit 1 condensate storage tank. The leak has since been repaired. Currently, there is no
evidence that the contamination has extended into the unrestricted areas.
This event is discussed in Preliminary Notification of Event or Unusual Occurrence
PNO-III-10-012A, dated July 22, 2010 (ADAMS Accession No. ML102030561).
Vermont Yankee
On January 7, 2010, the results of groundwater samples taken from an onsite groundwater
monitoring well indicated tritium contamination. The licensee determined that a pair of drain
pipes in the advanced off-gas pipe tunnel had corroded and were leaking nuclear plant steam, which contains tritium. In addition, the licensee found that the floor drain of the concrete tunnel
was blocked with construction waste, dirt, and mud which resulted in condensate from the
steam leak to collect inside the tunnel and leak out at a failed concrete joint and into the ground.
The licensee terminated the leak of tritiated water from the underground pipe tunnel and
cleaned the debris from the advanced off-gas pipe trench.
This event is discussed in Vermont Yankee Nuclear Power StationGround Water Monitoring
Inspection Report 05000271/2010006, dated May 20, 2010 (ADAMS Accession
No. ML101400040).
DISCUSSION
Leakage of structures, systems, and components (SSCs) that contain and transport radioactive
fluids can cause groundwater contamination. The detection of groundwater contamination may
be an early indicator of SSC degradation.
There are several causes for leaks and spills from various facility SSCs. The below table
summarizes some sources and causes of abnormal releases.
Sources and Causes of Abnormal Releases
Sources Causes
Spent fuel pool, Liner leakage, no liner, clogged leak detection drainage
reactor cavity, systems, overflow, incorrect valve alignments, expansion
refueling canal bellows failure, seal failure, spent fuel pool cooling pump leak
Outside storage tanks (e.g., Aluminum pipe failures (poor coatings, improper materials
condensate storage tank, selection), overflow (poor work practices or procedures),
refueling water storage tank, evaporation and condensation from vent lines
primary water storage tank)
Circulating water conduit, Degradation, poor design, vacuum breaker valve leakage, liquid waste discharge line, steam generator blowdown piping failure
steam generator blowdown
line
Pits, sumps (including turbine No liner, no leak detection system, clogged drains, no drains, building sump), vaults, basins, poor work practices; some of these events are design
cooling tower basins, trenches, discharge paths, hose breaks, inappropriate release paths, floor drains, etc. radwaste tank overfill, or cooling tower overflow that contacted
contaminated equipment
Engineered ponds or ditches No liner, clay liner, liner failure, poor or inappropriate work
on site property practices, poor design, lack of strategic planning, sometimes
associated with primary-to-secondary leakage
Normally clean system Contamination control practices, worker practices, maintenance
leakage, auxiliary boiler, evolutions, cross-contaminated DWST (work practices and
demineralized water storage procedures), pipe failure
tank (DWST)
CONTACT
This IN requires no specific action or written response. Please direct any questions about this
matter to the technical contact listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
/RA/
Timothy J. McGinty, Director
Division of Policy and Rulemaking
Office of Nuclear Reactor Regulation
Technical Contact:
Candace J. Clemons, NRR
301-415-5231 E-mail: Candace.Clemons-Webb@nrc.gov
Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Library.
ML120410213 TAC ME7178 OFFICE DRA/AHPB Tech Editor BC:DRA/AHPB D:DRA/NRR
NAME CClemons JDougherty UShoop JGitter SLee for
DATE 4/2/12 03/09/12 e-mail 4/3/12 4/4/12 OFFICE D:DWMEP/FSME BC:FSME/MSSA LA:PGCB/NRR PM:PGCB/NRR
NAME LCamper HFelsher for Duncan White CHawes DBeaulieu
DATE 03/07/12 via email 3/15/12 e-mail 4/9/12 4/5/12 OFFICE BC:PGCB:NRR LA:PGCB/NRR D:DPR/NRR
NAME KMorganButler CHawes TMcGinty
OFFICE 4/9/12 4/9/12 4/25/12