PNO-IV-06-001, Arizona Public Service Company - Followup for Tritium Contamination Found in Water Onsite
ML060760584 | |
Person / Time | |
---|---|
Site: | Palo Verde ![]() |
Issue date: | 03/17/2006 |
From: | Louis Carson, Shannon M NRC Region 4 |
To: | |
References | |
PNO-IV-06-001 | |
Download: ML060760584 (2) | |
March 17, 2006 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-IV-06-001 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region IV staff on this date.
Facility Licensee Emergency Classification Palo Verde Nuclear Generating Station Notification of Unusual Event Arizona Public Service Company Alert Tonopah, Arizona Site Area Emergency Docket: 50-528, 50-529, and 50-530 General Emergency License: NPF-41; NPF-51, and NPF-74 X Not Applicable
SUBJECT:
FOLLOWUP FOR TRITIUM CONTAMINATION FOUND IN WATER ONSITE DESCRIPTION:
On March 1, 2006, a water sample collected by the licensee from a test hole located within the licensees Unit 3 Protected Area identified tritium levels of 71,400 picocuries/Liter (pCi/L). On March 2, 2006, the licensee notified the Arizona Department of Environmental Quality (ADEQ) that a release of tritium had occurred that had the potential to cause the EPA drinking water limit (20,000 pCi/L) for tritium to be exceeded in a groundwater aquifer. As required by 10 CFR Part 50.72(b)(2)(xi) the licensee also notified the NRC (Event # 42381).
Since February 15, 2006, the licensee has been investigating the source of water leakage into an underground pipe tunnel located within the Protected Area of Units 2 and 3. Test holes were drilled inside the Protected Area in an area between all three Units power block and spray pond in an effort to find the source of the tritiated water. A water sample that contained the elevated tritium levels was from the Unit 3 test hole.
As part of the NRCs followup to the onsite elevated tritium levels, NRC Region IV obtained a split water sample from the Unit 3 test hole for the NRCs independent analysis on March 3, 2006. The NRCs independent laboratory analyzed the spilt sample for tritium and gamma radioactive isotopes and results were consistent with the 71,400 pCi/L value obtained by the licensee.
On March 6, 2006, NRC Region IV, dispatched a Senior Health Physicist to supplement the NRCs onsite resident staff and further review the licensee's actions. To date the NRCs review has determined: (1) The tritiated water at elevated levels is confined onsite; (2) No elevated levels have been found in wells located outside the Protected Area. From a review of the analyzed sample results from both onsite and offsite groundwater monitoring wells, the NRC has found no evidence of an offsite release of the radioactive water.
The apparent cause or source of the elevated tritium levels in the test holes has not been found/determined to date and is still under investigation by the licensee. NRC Region IV health physicists and the resident inspectors continue to monitor the licensees activities to address the source of the elevated tritium as well as and the licensees measures to ensure it will be confined onsite. NRC Region IV is in the process of obtaining additional environmental water samples from the Palo Verde site and surrounding areas.
The information presented herein has been discussed with the licensee and is current as of 11 a.m. (CST) on March 17, 2006.
ADAMS ACCESSION NUMBER: ML060760584 CONTACTS: Michael P. Shannon, Chief Louis C. Carson, II Plant Support Branch Senior Health Physicist 817-860-8215 817-860-8221 mps1@nrc.gov lcc1@nrc.gov