ML20217K858

NPDES Noncompliance Notification:On 990925,unusual Fish Kill Was Discovered That Consisted Predominately of Yellow Fin Croaker.Caused by Increased Temp in Intake Structure.Util Is Modifying Heat Treat Process to Reduce Possible Fish Kill

ML20217K858
Person / Time
Site:	San Onofre
Issue date:	10/21/1999
From:	Krieger R SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9910270003
Download: ML20217K858 (2)

Text

t OUINERN CAllIORNIA R. W. Krieger IB EDISON

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Nuclear Generation An EDISON INTERNATIONAL" Company

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October 21,1999 U. S. Nuclear Regulatory Commission l

l-Document Control Desk Washington, D.C. 20555 i

Subject:

Docket No. 50-361 Special Report - Unusual Fish Kill L

San Onofre Nuclear Generating Station, Unit 2 Gentlemen:

In accordance with Technical Specification, Appendix B, Section 4.1, of Facility Operating License No. NPF-10 for San Onofre Nuclear Generating Station, Unit l

2, this letter provides the required written report for an occurrence of an " unusual fish kill". As required by this License Condition, SCE provided a phone report to the NRC on September 25,1999 at 0941 PDT (NRC Log No. 36230).

Because San Onofre uses the Pacific Ocean for its ultimate heat sink, SCE periodically raises the temperature (heat treat) of the intake structure to limit biological fouling. Typically, the increased temperature in the intake structure forebay encourages fish to enter an elevator, which lifts them out of the forebay

. and returns them to the ocean. - This has proven to be an effective means of removing fish that would otherwise be killed by the heat treatment. Generally, a heat treat results in the loss of less than 1000 pounds of fish.

From about 2010 PDT Friday, September 24,1999 until about 0030 PDT Saturday, September 25, SCE was performing a heat treat of the Unit 2 intake structure. At about 0224 PDT, an unusual fish kill was discovered (about 4800 pounds) that consisted predominately of yellow fin croaker.

The following factors contributed to this occurrence:

~ 1. At this time of year, yellow fin croakers are inclined to be more abundant and move toward shore due to breeding conditions, and

2. The inter' mediate temperature plateau during the fish chase should I

have been held longer prior to increasing to the final fish chase targot temperature.

9910270003 991021-PDR ADOCK 05000361'-

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~ P. O. Box 128

/ h S:m Clemente. CA 92674-0128 I

949-368-6255 Fax 949-368-6183 j

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Document Control Desk October 21,1999 in response to this occurrence, SCE is modifying the heat treat process to reduce the possibility of an " unusual fish kill." SCE is continuing to evaluate this event.

Any additional required actions will be implemented though SCE's corrective actions program.

The above data will be included in the Marine Environmental Analysis and Interpretation Report.

Sincerely, W

cc:

E. W Merschoff, Regional Administrator, NRC egion IV J. A. Sloan, NRC Senior Resident inspector, San Onofre Units 2 and 3 l

L. Raghavan, NRC Project Manager, San Onofre Units 2 and 3 Institute of Nuclear Power Operations (INPO)