Information Notice 2004-05, Spent Fuel Pool Leakage to Onsite Groundwater
| ML040580454 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 03/03/2004 |
| From: | Beckner W NRC/NRR/DIPM/IROB |
| To: | |
| Hodge, CV, NRR/DIPM/IROB, 415-1861 | |
| References | |
| IN-04-005 | |
| Download: ML040580454 (7) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, DC 20555-0001
March 3, 2004
NRC INFORMATION NOTICE 2004-05:
SPENT FUEL POOL LEAKAGE TO ONSITE
GROUNDWATER
Addressees
All holders of operating licensees for nuclear power reactors (except those who have
permanently ceased operations and have certified that fuel has been permanently removed
from the reactor vessel) and for research and test reactors, and all holders of fuel storage
licenses and construction permits.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to inform
addressees of the recent identification of a longstanding leak to onsite groundwater from the
spent fuel pool of an operating pressurized water reactor facility. It is expected that recipients
will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice are not
NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances
On September 18, 2002, the licensee for the Salem Nuclear Generating Station identified
evidence of radioactive water leakage through an interior wall located at the 24-meter (78-foot)
elevation of the Unit 1 auxiliary building mechanical penetration room, a radiologically controlled
area. The leak location, about 3 meters (10 feet) up a wall surface, was identified while the
licensee was following up low-level shoe contamination of personnel who had traversed the
room. The licensee established a comprehensive task action plan to identify and stop the
source of the leakage and evaluate possibly undetected leakage outside building structures.
The licensee did identify other locations where radioactive water was leaking through interior
walls or penetrations into both the Unit 1 auxiliary building and the Unit 1 fuel handling building
(FHB).
On February 6, 2003, the licensee identified the radionuclide tritium (H-3) in groundwater in two
test locations near the Unit 1 FHB. The test locations were within the licensee-controlled
restricted area. The licensee identified other locations of groundwater contamination in the
general vicinity of the Unit 1 FHB and within the restricted area. No other reactor-produced
radionuclides were detected in the groundwater sampling test locations.
The licensee obtained technical support and concluded (based on leak testing of suspect
systems, chemical analysis of water samples, system and building configuration reviews, and a
geohydrological evaluation) that the likely source of the tritium was the Unit 1 spent fuel pool
(SFP). The licensee believes that the leakage was the result of the obstruction of the leakage
detection and collection system of the SFP stainless steel liner.
Discussion:
The Salem Unit 1 FHB is a seismically qualified structure that contains the Unit 1 SFP. Unit 1 SFP support systems in the Unit 1 auxiliary building pass through adjacent building walls to the
Unit 1 FHB. The walls are separated by a Styrofoam -filled 15-cm (6-inch) seismic gap and
the support systems traverse the seismic gap.
The Unit 1 SFP is a concrete structure with a stainless steel liner. The SFP includes an integral
liner leakage detection and collection system, consisting of an extensive network of collection
lines running both horizontally and vertically within the narrow gap between the SFP liner and
the concrete SFP structure. The collected liner leakage is discharged to a collection trough
through 17 drain lines (tell-tale drains). The tell-tale drains provide a means to detect, monitor, and quantify potential leakage from the SFP liner. The collected leakage is subsequently
directed to the liquid radioactive waste system for processing.
The licensees reviews discovered that over the years since initial facility startup, materials such
as boric acid residue and minerals accumulated within the leak collection and detection system
and restricted the normal drainage of liquid. The reviews also found that a modification to the
tell-tale drains in 1998 resulted in the inadvertent introduction of sealant into the tell-tale drains, further restricting the free drainage of leakage from the liner. As a result, through-liner leakage
accumulated between the SFP liner and the concrete structure of the SFP. The accumulated
water, containing tritium, subsequently migrated to other locations through penetrations, concrete construction joints, and cracks. The seismic gap was confirmed to contain water with
radionuclides characteristic of Unit 1 SFP water. The water is believed by the licensee to have
made its way to the groundwater in the restricted area via the seismic gap.
The licensee cleaned the tell-tale drains, improving the drainage of the accumulated water
between the liner and spent fuel pool concrete structure and stopping the through-wall and
penetration leakage. After the cleaning effort, the leak rate from the tell-tale drains increased
from about 19 liters per day (5 gallons per day) to about 380 liters per day (100 gpd). The
leakage was properly collected.
The NRC conducted a special inspection of this issue (NRC Inspection Report 50-272/2003-
006; 50-311/2003-006, ADAMS Accession No. ML032890212). The NRCs and the licensees
reviews identified the following information about this situation. 1.
The licensee took actions to identify specific leak locations, repair and mitigate the leak, and assess potential health and safety impacts. A comprehensive groundwater
sampling and analysis program was implemented. Although the licensee believes, with
a high degree of confidence, that the leak originated from the SFP, the licensee is
continuing evaluations to confirm this conclusion. The leakage itself was not
accompanied by large fluctuations in SFP water levels and was likely masked by
approximately equal volumes of evaporation from the SFP.
2.
The licensee stopped the identified through-wall leakage by cleaning the tell-tales and
resumed controlled collection of SFP liner leakage via the installed leakage detection
and collection system. Extent-of-condition reviews revealed no apparent accumulation
of water between the SFP liner and concrete structure at Salem Unit 2.
3.
The licensees evaluations did not identify any immediate health and safety
consequences to onsite workers or members of the public. No radionuclides associated
with the leakage were detected outside the onsite areas administered as access- controlled areas for purposes of radiation protection. The licensee did not detect any
tritium associated with this leak in areas accessible to the public (i.e., the unrestricted
area). The licensee subsequently developed and implemented an onsite groundwater
remedial investigation work plan in conjunction with State of New Jersey
representatives.
4.
The Unit 1 SFP had exhibited detectable leakage from the tell-tales since initial plant
operations. To monitor leakage from the tell-tales, the licensee established a
surveillance program. Over the years, the leakage from the tell-tales diminished but the
licensee was not able to tell from leakage changes if they needed further evaluation.
There was also a missed opportunity to evaluate earlier through-wall contaminated
leakage for possible accumulation of water between the Unit 1 FSP liner and concrete
structure.
5.
There was no periodic maintenance of the SFP leakage detection and collection system
to ensure that drainage channels remained free and clear so that the system could
perform its design function of preventing water from accumulating behind the FHB walls.
The licensee initiated actions to develop a cleaning and maintenance process.
6.
The licensee conducted evaluations of potential short-term adverse impacts to the SFP
structure. The preliminary evaluations did not identify any adverse effects that would
impact the design bases of the SFP or FHB structure. Nonetheless, the licensee
initiated laboratory testing of the effects of boric acid on concrete. The results of these
tests are being evaluated by the licensee for potential long-term effects.
The licensee developed numerous corrective action documents to track the review, evaluation, and correction of identified deficiencies. This information notice requires no specific action or written response. If there are any
questions about this notice, contact one of the persons listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
/RA/
William D. Beckner, Chief
Reactor Operations Branch
Division of Inspection Program Management
Office of Nuclear Reactor Regulation
Technical Contacts: Ronald Nimitz, Region I
Stephen Klementowicz, NRR
(610) 337-5267
(301) 415-1084 E-mail: rln@nrc.gov
E-mail: sxk@nrc.gov
Suresh Chaudhary, Region I
Jason Jang, Region I
(610) 337-5335
610-337-5220
E-mail: skc@nrc.gov
E-mail jcj@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
ML040580454 OFFICE
OES;IROB;DIPM
TECH EDITOR
REGION 1 SC;OES;IROB;DIPM
NAME
VCHODGE
PKleene
RNIMITZ
TREIS
DATE
02/ /2004
02/10 /2004
02/26/2004
02/25/2004 OFFICE
C;IROB;DIPM
NAME
WDBECKNER
DATE
03/03/2004
______________________________________________________________________________________
OL = Operating License
CP = Construction Permit
Attachment LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
_____________________________________________________________________________________
Information
Date of
Notice No.
Subject
Issuance
Issued to
_____________________________________________________________________________________
2004-04
Fuel Damage During Cleaning
at a Foreign Pressurized Water
Reactor
02/24/2004
All holders of operating licenses
for light-water reactors, except
those who have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor.
2004-03
Radiation Exposures to
Members of the Public in
Excess of Regulatory Limits
Caused by Failures to Perform
Appropriate Radiation Surveys
During Well-logging
Operations
02/24/2004 All well-logging licensees.
2004-02 Strontium-90 Eye Applicators
New Calibration Values and
Use
02/05/2004
All U.S. Nuclear Regulatory
Commission (NRC) medical-use
licensees and NRC master
materials license medical-use
Permittees.
2004-01
Auxiliary Feedwater Pump
Recirculation Line Orifice
Fouling - Potential Common
Cause Failure
01/21/2004
All holders of operating licenses
or construction permits for
nuclear power reactors, except
those that have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor.
Note:
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