ML19346A406

Responds to IE Bulletin 81-03.Corbicula & Mytilus Were Not Present in Station Vicinity During Sept 1980 Survey.Small Number of Shells Have Been Found in Main Condenser Water Boxes,But Not in Any Heat Exchanger

ML19346A406
Person / Time
Site:	Prairie Island
Issue date:	05/22/1981
From:	Gilberts D NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-81-03, IEB-81-3, NUDOCS 8106190281
Download: ML19346A406 (3)

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i Northern States Power Company

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414 Nicollet Mall D.E. Gilberts Minneapolis. Minnesota 55401 sen6or vice Pressoent Telechone (612) 330-6071 Power Supply May 22, 1981 9'v\\ \\W lhkM Mr. James G. Keppler s ?

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Office of Inspection and Enforcement 4

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U. S, Nuclear Regulatory Consnission M/

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Dear Mr. Keppler:

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PRAIRIE ISLAND NUCLEAR GENERATING PIAYr Docket Nos. 50-282 and 50-306 Response to I. E. Bulletin No. 81-03 In response to I. E. Bulletin No. 81-03, the following information is offered. Items 2 and 3 were ignored based on the guidance in the Bulletin.

1.

A survey completed in September 1980 shows that Corbicula sp. or Mytilus sp. are not present in the vicinity of this station.

4.

The intakes for the two horizontal cooling water pumps are located behind traveling screens and two feet off the screen well floor be-tween the two condenser circulating water intakes. The three vertical pumps (two of which are safeguards pumps) are located in their own safe-guards bay. They take water from the circulating water bay and from a 30" amergency intake pipe that turns to the middle of the river. Under worst case conditions the 30" line will supply water to the two safe-guards pumps. The safeguards bay has its own safeguards traveling screens.

Water from all the cooling water pumps goes through strainers with 1/16" openings. The strainers are backwashed automatically. There are low flow alarms on each cooling water supply header. There are flow indicators on each of the component cooling heat exchangers outlet lines and on both the inlet and outlet of the containment fan coil units.

Each year all component coolin heat exchangers are opened and inspected for fouling. Each refueling outage various other heat exchangers are opened and inspected for fouling.

It is felt that the flow monitoring instrumentation available and the preventive maintenance program are arlequate to detect flow degradation.

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• Mr. James G. Keppler Page 2 May 22, 1981 5.

A survey completed in September 1980 showed that there are mussels actively reproducing near the station, but at a relatively low den-sity.

A small number of shells have been found in main condenser water, boxes, but not in any heat exchanger supplied by cooling water.

Sig?.ificant fouling of cooling water heat exchangers has not been seen.

No corrective or additional preventive actions are deemed necessary.

Yours truly,

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D. E. Gilberts Senior Vice Presidens Power Supply cc:

Mr. G. Charnoff '

Mr. C. D. Feierabend Director, Office of Inspection and Enforcement U. S. Nuclear Regulatory Comission Washington, D. C.

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UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 and 50-306 LErn.h DATED MAY 22, 1981 RESPONDING TO NRC REQUEST FOR INFORMATION IN I. E. 3ULLETIN NO. 81-03 Northern States Power Company, a Minnesota corporation, by this letter dated May 22, 1981, hereby submits inform

..on in response to NRC request for in-formation concerning I. E. Bulletin No. 81-03.

This request contains no restricted or other defense information.

NORTHERN PTATES POWER COMPANY By:

D. E. Gilberts Senior Vice President Power Supply On this,[ b day of EO' 19 [/

, before me a notary public in and for said County, persdnally appeared D. E. Gilberts, Senior Vice President Power Supply, and being first duly sworn scknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information and belief, the statements made in it are true and that it is not interposed for delay.

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