ML20215F815

Submits Addl Info for Justification of Interim Operation of Backup Containment Spray Valve Per Discussions During Wk of 860915.Min Required Valve Position to Attain Rated Containment Spray Less than 10% Open

ML20215F815
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	10/10/1986
From:	Frisch R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8610160387
Download: ML20215F815 (2)

Text

J Consumers

@paiemums Power AIENIEAF5 PBSEftE55 oeneral offices: 1945 West Parnati Road, Jackson, MI 49201 * (517) 788-0550 October 10, 1986 Director, Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLAN'I -

ADDITIONAL SUPPORTING INFORMATION FOR JUSTIFICATION FOR INTERIM OPERATION OF BACKUP CONTAINMENT SPRAY VALVE M0-7068 During Region III's audit of our Electrical Equipment Environmental Qualification Program the week of September 15, 1986, considerable discussion centered around operation of backup containment spray valve MO-7068. Among the questions asked by the Region was one pertaining to the minimum position that the valve must open in order to attain rated containment spray flow. In response, we stated that this gate valve could be expected to deliver over 250% required flow in the fully open position and that an evaluation of flow rates at intermediate valve positions could be easily performed.

The referenced analyses have been completed and suggest that the minimum required valve position to attain rated containment spray is less than 10%

open. This letter summarizes the details of the analysis.

4 l

The FLOWNET code used to establish the current design basis for the '

containment spray system was used to perform this analysis. This is the same code referenced in our December 5, 1980 Technical Specification change request and the Staff's January 13, 1981 safety evaluation report concerning the design of the containment spray system.

As in the referenced design analysess calculations were performed assuming two different LOCAs; an ECCS line break as well as a break in a non-ECCS pipe.

The configuration of ECCS components was assumed to be as follows:

- Both fire pumps in opct..cion

- Both core spray lines fully open

- Primary containment spray valve M0-7064 failed closed (the assumed single failure)

- Backup containment spray valve M0-7068 partially open 4

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PDR ADOCK 05000155 P PDR

s Director, Nuclear Reactor Regulation 2 Big Rock Point Plant Add'l Info - Backup Containment Spray Valve MO-7068 October 10, 1986 Calculations were performed varying the equivalent length (L/D) of the connector associated with valve MO-7068 until the minimum required 50 gpm containment spray flow rate was attained. In this manner an equivalent length of approximately 200;000 for the backup containment spray valve was determined to permit the minimum required flow rate.

Commonly available literature does not provide detailed conversion of equivalent length to valve position for L/Ds of this size. Crane Catalogue

1. 60, as an example, provides information only down to 25% valve opening (L/D =

900) and also Idel'Chik/AEC TR-6630 only down to 25% (L/D = 1200). Estimation from this data, however, suggests that the minimum required valve position is well under 10% open.

N Ra h R Frisch Senior Licensing Analyst CC Administrator, Region III, USNRC NRC Resident Inspector - Big Rock Point Plant OC1086-0150-NLO4

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