05000275/LER-2006-001

LER-2006-001,

Event date:
Report date:
2752006001R00 - NRC Website

I. Plant Conditions

Pacific Gas and Electric Company (PG&E) Units 1 and 2 were in Mode 1 (Power Operation) at approximately 100 percent reactor power during the event.

A. Background

PG&E's Diablo Canyon Nuclear Generating Station, Units 1 and 2, Docket Nos. 50-275 and 50-323, Facility Operating Licenses Nos. DPR-80 and DPR-82, Appendix B, "Environmental Protection Plan (non-radiological)" (EPP), dated August 1985, Subsection 4.1, "Unusual or Important Environmental Events," requires, in part, that, "Any occurrence of an unusual or important event that indicates or could result in significant environmental impact causally related to station operation shall be recorded and promptly reported to the NRC within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by telephone, telegraph, or facsimile transmissions followed by a written report within 30 days, as specified in Subsection 5.4.2." The EPP describes, "excessive bird impaction events," as an example.

EPP Subsection 5.4.2, "Nonroutine Reports," states, in part, "A written report shall be submitted to the NRC within 30 days of occurrence of {a} nonroutine event. The report shall (a) describe, analyze, and evaluate the event including extent and magnitude of the impact and operating characteristics, (b) describe the probable cause of the event, (c) indicate the action taken to correct the reported event, (d) indicate the corrective action taken to preclude repetition of the event and to prevent similar occurrences involving similar components or systems, and (e) indicate the agencies notified and their preliminary responses.

Cooling water for Diablo Canyon Power Plant (DCPP) Units 1 and 2 is obtained by pumping Pacific Ocean sea water from an intake structure that incorporates a heavy bar or trash rack ahead of the moving debris removal screens. PG&E routinely sends commercial divers into the area in front of the bar racks to check for accumulation of debris and assist in its removal.

Cormorants are diving sea birds and are common to the California Central Coast and often feed in the DCPP intake cove. The cormorants have recently started nesting in larger numbers on a large rock at the southern end of the intake cove.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) B. Event Description [EPP 5.4.2(a)] On August 15, 2006, a commercial diver discovered approximately 100 dead cormorants during scheduled plant diving operations to clean intake bar racks.

On August 15, 2006, a nonemergency report in accordance with EPP, Subsection 4.1 as an "Unusual or Important Environmental Event," requiring NRC notification within 24-hours was made at 15:21 PDT.

On August 16, 2006, PG&E transferred the remains of four cormorants to the California Department of Fish and Game (CDF&G) who transported the bird samples to California Animal Health and Food Safety (CAHFS) Laboratory at the University of California at Davis, California (UCD), for testing and analysis.

C. Status of Inoperable Structures, Systems, or Components that Contributed to the Event None.

D. Other Systems or Secondary Functions Affected None.

E. Method of Discovery The dead birds were found during routine scheduled cleaning of the DCPP cooling water intake structure bar racks.

F. Operator Actions None.

G. Safety System Responses None.

III.�Cause of the Problem [EPP 5.4.2(b)] A.�The number of dead birds found is unusual. Thus, an investigation was initiated to determine the cause in accordance with the requirements of the EPP. The remains of four cormorants were transferred to the CDF&G LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) for transport to the CAHFS Laboratory at the UCD, for testing and analysis. Also regional water samples from the Central Coast during the week were reviewed for algae and toxin production associated with an algae bloom, or red tide. Ongoing monitoring of the bar racks found no further incidents of excessive accumulation of dead birds.

B.ARoot Cause The gross examination findings, demographics, and historical information are most suggestive of a toxic, viral, or unusual stochastic event as the cause of the cormorant deaths.

The testing of bird tissue samples for domoic acid toxin were all negative.

Toxicosis from domoic acid or another harmful algal bloom has been ruled out to the best of the CAHFS' testing ability. Further investigation of a viral etiology, other type of toxicosis, or stochastic etiology will be dictated by histologic findings. These results will not be available until late October.

PG&E believes that the birds died of natural causes and collected on the bar racks due to the intake cooling water currents, and the event was not related to plant operation. If the CAHFS testing described above identifies a cause related to plant operation, a supplement to this report will be submitted.

IV.AAssessment of (Environmental) Safety Consequences [EPP 5.4.2(a)] There were no actual safety consequences involved in this event since plant operation was not affected, and routine scheduled cleaning of the DCPP cooling water intake structure bar racks ensures adequate plant cooling is maintained.

There is no environmental safety consequences identified based upon PG&E's belief that the bird deaths are due to a naturally occurring cause.

Also, this condition is not considered a Safety System Functional Failure.

Therefore, the event is not considered risk significant, and it did not adversely affect the health and safety of the public.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) V.�Corrective Actions [EPP 5.4.2.(c)] A. Immediate Corrective Actions The dead birds were removed and forensic evidence sent to CDF&G, and transferred to CAHFS for additional testing and analysis.

B. Corrective Actions to Prevent Recurrence PG&E believes that the birds died of natural causes and collected on the bar racks due to the intake cooling water currents, and the event was not related to plant operation. Since the deaths are not believed to be related with DCPP operation, no corrective actions were identified.

VI.�Additional Information [EPP 5.4.2(e)] A. Other agencies notified and their preliminary responses:

The CDF&G, the CAHFS, the United States Fish and Wildlife Service, and the Regional Water Quality Control Board.

The gross examination findings, demographics, and historical information are most suggestive of a toxic, viral, or unusual stochastic event as the cause of the cormorant deaths. Testing of bird tissue samples for domoic acid toxin were all negative.

B. Previous Similar Events

None.