ML19253B822

Forwards Proposed Tech Spec Mods Re Overpressure Protection Sys,In Response to Telcon Requests

ML19253B822
Person / Time
Site:	North Anna
Issue date:	10/18/1979
From:	Brown S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML19253B823	List: ML19253B822 ML19253B826
References
819, NUDOCS 7910220283
Download: ML19253B822 (4)

Text

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VInOINIA ELEC~rRIC Axn Powen CO31MNY Hrcuxonn,Vxnotw zA nau61 October 18, 1979 Mr. Harold R. Denton, Director Serial No. 819 Office of Nuclear Reactor Regulation LQA/ESG:pwc Attn: Mr. 0..D. Parr, Chief Light Water Reactors Branch No. 3 Docket Nos. 50-338 Division of Project Management 50-339

.U. S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Denton:

Our letter of Aaril 17, 1979, Serial No. 214/03?l79, provided you with dehe N concerning our proposed overpressure protection system for North Anna Units 1 and 2. Recent telephone conversations with members of the Staff and its consultants have revealed additional requirements which must be satisfied by the system. Accordingly, we have modified the system design and proposed technical specifications to address the Staff comments.

For Reactor Coolant System temperatures between 3200F and 340 F, we have proposed (on Unit 2) that maximum pressurizer level be limited, in lieu of requiring both power operated relief valves (PORVs) to be operable. The Staff has indicated that this approach is acceptable, provided that an alarm be pro-vided during this interval to warn the operator that an overpressure event is in progress. Such an alarm, meeting the requirements of the Staff, will be provided on Unit 2 prior to fuel loading. A schematic of the alarm circuitry is attached.

Utilization of a pressurizer bubble for overpressure protection will not be necessary for Unit 1. Consequently, protection will be provided by the PORVs over the entire temperature range of interest. We will revise our re-quest of August 6,1979 (Serial No. 629) for an amendment to the Unit 1 operat-ing license in the near future to reflect this. No additional alarms will be required for Unit 1 with these provisions for overpressure protection.

Also discussed with the Staff were the power source assignments for the overpressure protection system and the Reactor Coolant System letdown isolation valves. In rder to ensure that loss of a power source would not both isolate letdown, and also disable one PORV circuit, the PORV electronics for PT402 will be moved from Cabinet #1 (Red) to Cabinet B (White). Power for the S0Vs for this channel will also be from the (White) source. Since this will result in the letdown isolation valves and the FORV circuits being supplied from separate power sources, this change will satisfactorily address the Staff's concerns in this area. This change will be completed prior to fuel loading for Unit.2. A similar change will be made in the Unit 1 design, and will be implemented during installation of the overpressure protection system during the current refueling outage.

1150 138 q 91 0220 *6

Vracix A ELECTRIC AND Powra COMPANY TO Hud *. ham 2.

Several minor revisions have been made to the proposed Unit 2 technical specifications to reflect the final system design and Staff comments. The revised specifications are attached.

Based on the above information, we believe that the Staff should now be able to complete its review, and to conclude that the overpressure protection systems for North Anna Units 1 and 2 are acceptable.

Very trulf'yours

-[

~

Sam C. rown, Jr.

Senior Vice President-Power Station Engineering and Construction At tach'e:

(1) Unit 2 Alarn Design for 3200-340 F Operation (2) P oposed Unit 2 Technical Specifications cc: Mr. A. Schwencer, Chief Operating Reactors Branch No. 1 1150 i39

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