Information Notice 2012-05, Abnormal Releases of Radioactive Water Potentially Resulting in Groundwater Contamination

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)

ML120410213

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, reactor cavity, refueling canal

Liner leakage, no liner, clogged leak detection drainage

systems, overflow, incorrect valve alignments, expansion

bellows failure, seal failure, spent fuel pool cooling pump leak

Outside storage tanks (e.g.,

condensate storage tank, refueling water storage tank, primary water storage tank)

Aluminum pipe failures (poor coatings, improper materials

selection), overflow (poor work practices or procedures),

evaporation and condensation from vent lines

Circulating water conduit, liquid waste discharge line, steam generator blowdown

line

Degradation, poor design, vacuum breaker valve leakage, steam generator blowdown piping failure

Pits, sumps (including turbine

building sump), vaults, basins, cooling tower basins, trenches, floor drains, etc.

No liner, no leak detection system, clogged drains, no drains, poor work practices; some of these events are design

discharge paths, hose breaks, inappropriate release paths, radwaste tank overfill, or cooling tower overflow that contacted

contaminated equipment

Engineered ponds or ditches

on site property

No liner, clay liner, liner failure, poor or inappropriate work

practices, poor design, lack of strategic planning, sometimes

associated with primary-to-secondary leakage

Normally clean system

leakage, auxiliary boiler, demineralized water storage

tank (DWST)

Contamination control practices, worker practices, maintenance

evolutions, cross-contaminated DWST (work practices and

procedures), pipe failure

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

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UShoop

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DATE

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3/15/12 e-mail

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