ML19207C172

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Submits Info Clarifying Safety Evaluation Authorizing Cycle 3 Operation
ML19207C172
Person / Time
Site: Millstone Dominion icon.png
Issue date: 08/31/1979
From: Counsil W
NORTHEAST UTILITIES
To: Reid R
Office of Nuclear Reactor Regulation
References
TAC-46174, NUDOCS 7909070349
Download: ML19207C172 (2)


Text

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) HARTF oRo. CONNECTICUT 06101 (203) 666 4 911 k L J August 31, 1979 Docket No. 50-336 Director of Nuclear Reactor Regulation Attn: Mr. R. Reid, Chief Operating Reactors Branch #4 U. S. Nuclear Regulatory Commission Washington, D. C. 20555

References:

(1) R. Reid letter to W. G. Counsil dated May 12, 1979.

(2) k. G. Counsil letter to R. Reid dated March 22, 1979.

(3) W. G. Counsil letter to R. Reid dated December 28, 1978.

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Safety Evaluation Authorizing Cycle 3 operation During Nortbeast Nuclear Energy Company's (NNECO) review of the Safety Analysis (SE) supporting Reference (1), several items meriting clarification have been identified.

NNECO is currently taking credit for charging pump flow in the analysis of small break loss-of-coolant accident (LOCA) as authorized by Reference (1) .

In this analysis, the flow rate justified by Reference (2) is one half the capacity of one charging pump. The capacity of these pumps is 44 gpm as reported in Part 9.2.2.2 of the Millstone Nuclear Power Station, Unit No. 2 Final Safety Analysis Report (FSAR), and justified by tests of the system.

Parts 2.5.1.3 and 2.5.1.11 of the SE incorrectly report this flow rate to be 20 gpm. NNECO hereby clarifies that the flow rate from the charging pumps, which has been credited in the small-break LOCA analysis of Reference (1), is 22 gpm.

The 22 gpm value is that flow which will be delivered to the core assuming a worst-case break location.

In Part 2.5.1.8 of the SE, the NRC Staff concludes that certain portions of the charging system inside containment are environmentally qualified. This qualification included Valves 2-CH-518 and 2-CH-519. These valves are redundant charging line diw ribution valves remotely operated from the control room. They do not receive a Safety Injection Actuation Signal (SIAS) but must be open to allow flows from the charging pumps to the Reactor Coolant System. The solenoids on these valves were previously not environmentally qualified. The safety-related design function of these valves was assured via administrative control.

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.' o During the outage commencing August 8, 1979, NNECO replaced the solenoids on Valves 2-Cll-518 and 2-Cll-519 with environmentally qualified solenoids. Please be advised that key lock switches have also been installed on these two valves to further ensure they are in the open position when the system is required to operate. The keys to these locks are maintained by the Shif t c

opervisor.

We trust this information clarifies several questions pertaining to the Safety Evaluation.

Very truly yours, NORTliEAST NUCLEAR ENERGY COMPANY

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