ML20198L068

Responds to IE Compliance Bulletin 86-001, Min Flow Logic Problems That Could Disable RHR Pumps. Single Failure Would Not Cause All Min Flow Valves to Be Inoperable,Therefore Plant Does Not Have Single Failure Vulnerability

ML20198L068
Person / Time
Site:	Monticello
Issue date:	05/30/1986
From:	Larson C NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-86-001, IEB-86-1, NUDOCS 8606040200
Download: ML20198L068 (2)

Text

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,#i)f DmB Northern States Power Company 414 Nicollet Mall Minneapoks. Minnesota 55401 Telephone (612) 330-5500 May 30, 1986 Mr James G Keppler, Director Region III, Office of Inspection & En:arcement U S Nuclear Regulatory Commission 799 Roosevelc Road Glen Ellyn, IL 60137 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Response to IE Compliance Bulletin 86-01 IE Compliance Bulletin 86-01 " Minimum Flow Logic Problems That Could Disable RHR Pumps", was issued for action to all GE BWR plants. The action required is to determine if the RHR minimum flow logic at the Monticello Nuclear Plant is vulnerable to a single failure that could result in all four RHR pumps running with no minimum flow path established.

The following is provided in response to IE Compliance Bulletin 86-01.

A review of the piping diagrams and logic diagrams at the Monticello Nuclear Plant was completed and the following conclusions can be drawn:

1. Each RHR pump is provided with its own minimum flow valve ard flow sensing instrument. The flow instrument is located on the discharge of the pump it serves before the discharge line branches into the common header. The minimum flow line branches off the pump discharge ahead of the pump discharge check valve. The minimum flow valves all operate independently to provide a minimum flow path for the associated RHR pump.

2. The logic circuits for control of the RHR pump minimum flow valves are all independent circuits and do not share any common components.

Based on the above conclusions, it can be stated that no single failure would cause all four minimum flow valves to be inoperable. Therefore the Monticello Nuclear Plant does not have the single failure vulnerability described in IE Compliance Bulletin 86-01.

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[ m C E Larson )

Vice President Nuclear Generation CEL/ dab c: Document Control Desk, NRC Project Manager, NRC Resident Inspector, NRC G Charnoff \\

8606040200 860530 PDR ADOCK 05000263 JUN 2 M G PDR

. a UNITED STATES NUCLEAR REGULATORY COMMISSION NORTilERN STATES POWER COMPANY k

MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 RESPONSE TO IE COMPLIANCE BULLETIN 86-01 4

Northern States Power Company, a Minnesota corporation, by this letter dated May 30, 1986 hereby submits the response to IE Compliance Bulletin 86-01 for the Monticello Nuclear Generating Plant.

This letter contains no restricted or other defense information.

NORTHERN STATES POWER COMPANY By [ W C E Larson y Vice President, Nuclear Generation On this 30_f/ day of ~8/ag , /9/d before me a notary public in and for said County', personally apfeared C E Larson, Vice President, Nuclear Generation,

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f and being first duly sworn acknowledged that he is auttarized 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 state-ments made in it are true and that it is not interposed for delay, h~ ._ L_W

. : [ bO A. BROS $ l lg NOTARY PUBUC - MINNESOTA l ,

HENNEPIN COUNTY ll My commmelon Empires Dec. 26,1989 l,,

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