ML13317A796

Advises of Final Design Mod,In Response to NUREG-0578 Requirement Re Rerouting Waste Gas Surge Tank Relief Valve Vent to Station Stack Via Filters

ML13317A796
Person / Time
Site:	San Onofre
Issue date:	12/22/1981
From:	Baskin K Southern California Edison Co
To:	Crutchfield D Office of Nuclear Reactor Regulation
References
RTR-NUREG-0578, RTR-NUREG-578, TAC-44128 NUDOCS 8112240132
Download: ML13317A796 (3)

Text

Southern California Edison Company

. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 K. P. BASKIN TELEPHONE MANAGER OF NUCLEAR ENGINEERING, December 22, 1981 (213) 572-1401 SAFETY. AND LICENSINGDembr2,18 Director, Office of Nuclear Reactor Regulation Attention:

D..M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.

20555 Gentlemen:

Subject:

Docket No. 50-206 NUREG-0578, Item 2.1.6.a

/3 San Onofre Nuclear Generating Station Unit 1

References:

1. Letter, K. P. Baskin, SCE, to D. G. Eisenhut, NRC, Additional Information in Support of Responses to NRC TMI Requirements, January 17, 1980

2. Letter, D. G. Eisenhut, NRC, to All Operating Nuclear Power Plants, Radioactive Release at North Anna Unit 2 and Lessons Learned, October 17, 1979

3. Letter, K. P. Baskin, SCE, to D. M. Crutchfield, NRC, Clarification of TMI Action Plan Requirements, December 8, 1981 In Reference 1 we provided a response to Reference 2 by a survey of systems outside of containment that are likely to contain radioactive materials and are required to function in the course of achieving cold, stable conditions following an accident. The modification identified in Reference 1 was to reroute the Waste Gas Surge Tank relief valve vent to the station stack via the filters. We stated this modification would be deferred pending completion of the integrated assessment of potential modifications identified by review of station design and operation in connection with the Systematic Evaluation Program (SEP).

This correspondence is to advise you of the final design modification in response to the subject NUREG-0578 requirement and to identify the completion date of the modification.

8112240132 811222 PDR ADOCK 05000206 P

PDR>

Mr. D. M. Crutchfield

-2 The modification as identified in Reference 1 was to reroute the Waste Gas Surge Tank vent to the station stack via the filters. Presently this vent relieves to the Liquid Waste Hold-up Tanks with an over-pressurization relief on the Liquid Waste Hold-up Tanks which is routed to the stack.

However, there also exists a liquid over-fill and over-pressurization relief line which extends through the roof and loops back into the floor drains (as shown in the attached sketch).

The anti-syphon vent on top of this loop provides a potential leakage pathway on top of the Auxiliary Building. An engineering review of this system configuration has indicated the problem exists for other vents which relieve to the Liquid Waste Hold-up Tanks and the final design reflects this review.

The final design modification (as shown in the attached sketch) would allow the relief of the Liquid Waste Hold-up Tanks, but would preclude the release of any post-accident radioactive materials by routing the anti-siphons vents back into the floor drains.

It is planned that this modification will be completed in the unit outage scheduled on or before May 1, 1982 as noted in Reference 3.

If you have a need for additional information or have any questions, please let me know.

Very truly yours, Enclosure

Attachmrent D.C. 81-13 2 in.

2 in.

12/21/81 Aux. Building Roof 6 in.

4 in.

4in.

C-20A C-20B C-20C EXISTING CONFIGURATION 2 in.

6 in.

core drilled (to be resealed)

Aux. Building Roof 6 in.

4 in.

4 in.

C-20A C-20B C-20C Routing to drain to be added we ALARA concerns permit.

PROPOSED CONFIGURATION SKETCH:

Proposed routing of Liquid Radwaste Holdup Tank Loop Vents (not to scale).