ML20235F714

Responds to NRC Re Deviations Noted in Insp Rept 50-312/87-14.Based on Encl Bechtel 870625 Evaluation, Application of Dow Corning 732 RTV Silicone Sealant in Essential HVAC Sys Acceptable

ML20235F714
Person / Time
Site:	Rancho Seco
Issue date:	06/30/1987
From:	Andognini G SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Miraglia F Office of Nuclear Reactor Regulation
References
RTR-REGGD-01.052, RTR-REGGD-1.052 GCA-87-075, GCA-87-75, NUDOCS 8707130515
Download: ML20235F714 (3)

Text

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gSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O P. O. Box 15830, Sacramento CA 95852-1830,(916) 452-3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA GCA 87-075 JUN 3 01987 U. S. Nuclear Regulatory Commission Attn: Frank J. Miraglia, Jr.

Associate Director for Projects Philips Building 7920 Norfolk Avenue  !

Bethesda, MD 20014 APPLICATION OF DON CORNING 732 RTV SILICONE SEALANT IN ESSENTIAL HVAC SYSTEMS

Dear Mr. Miraglia:

In the transmittal letter dated April 12, 1987, for NRC Inspection Report 50-312/87-14, the Sacramento Municipal Utility District received a Notice of Deviation concerning the District's deviation from certain recommendations of Regulatory Guide 1.52, " Design, Testing and Maintenance Criteria for Post Accident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and Absorption Units of Light-Water-Cooled Nuclear Power Plants", Rev. 2, March 1978. Specifically, the District had applied Dow Corning 732 RTV Silicone Sealant to ductwork and mounting framework of the Control Room (CR)/

Technical Support Center (TSC) Essential HVAC System.

As committed in the District's response to the Notice of Deviation, dated May 27, 1987, Bechtel Power Corporation's evaluation of Dow Corning 732 RTV Silicone Sealant is enclosed. This evaluation provides the results of Bechtel's study of Dow Corning 732 RTV Silicone Sealant in Rancho Seco's CR/TSC Essenti:;i HVAC System. Based on the conclusions in the Bechtel evaluation, the District considers the application of Dow Corning 732 RTV Silicone Sealant to be acceptable.

If you have any questions regarding this matter, please contact Ron H. Colombo at (916) 452-3211, extension 4236.

Sincerely, fGWY .s Carl ndogpini

.awa--

Chief Executive Officer, Nuclear Attachment g71%$ h 2 O

cc w/atch:

G. Kalman, NRC, Bethesda (2)

A. D' Angelo, NRC, Rancho Seco y J. B. Martin (2) , O INPO I&E kt RANCHO SECO NUCLEAR GENERATING STATION O 1444o Twin Cities Road, Herald, CA 95638 9799;(2o9) 333-2935

i.

Bechtel Western Power Corporation Engineers - Constructors Fifty Beale Street ^

San Francisco. Cahfornia Mad Address: PO Box 3965. San Franc <sce cA 94119 June 25, 1987 Letter No. BSL-6781 Mr. G. V. Cranston Manager, Nuclear Engineering Department Rancho Seco Nuclear Generating Station Sacramento. Municipal Utility District 14440 Twin Cities Road Herald, CA 95638  ;

I

Subject:

Rancho Seco Nuclear Generating Station, Unit #1 Bechtel Job 12334, SMUD Task 037 Qualification of Silicone Sealant - Dow Corning 732 RTV Applied in CR/TSC HVAC Ductwork and Access Doors

References:

1. Bechtel Letter to SMUD, December 19, 1984, Letter-No. BSL-4403,

Subject:

Startup Field Report and Blue Memo's

2. EPRI. Report NP-4172 SP, August 1985, Radiation Data for Design and Qualification of Nuclear Plant Equipment

3. EPRI Equipment Qualification Data Bank, Radiation Records, Page 13, Dated 05-11-87; and KING, R.W. et al, The Effects of Nuclear Radiation on Elastomeri'c and Plastic Components and Materials, Battelle memorial Institute, Report REIC 21, 1961

4. Rancho Seco ERPT-E0187 and Drawings M-421; NCR No.

S 6576, Rev. 1, dated 04-02-87; and Office Memorandum from Dave Abbott to Mike Parenteau, December 27, 1984,

Subject:

MOD 032-Startup Field Report No. 07-84 Silicone RTV Elastomer

Dear Mr. Cranston:

This. letter is to further clarify Reference 1 with regard tn the radiation qualification of silicone sealant Dow Corning 732 RTV which has been used for  ;

the Control Room / Technical Support C' enter HVAC ductwork and access doors.

Bechtel has concluded that the RTV silicone sealant that is located in a mild.

environment is qualified and acceptable, based on the following:

1. Radiation resistance of sealant is as follows:

o EPRI report NP-4172 SP (reference 2) states that the radiation level for no deterioration of propgrties of silicone sealant (Dow Corning 732 RTV) is 7.0 x 10 rads.

t.

.Bechtel Western Power Corporation t- Mr. G. V. Cranston Letter No. BSL-6781 Page Two June'24, 1987 6

o The threshold value for the generic silicone sealants' is 1.3 x 10 rads in accordance with the EPRI equipment qualification data bank report (reference 3).

2. . Sealant is located in a mild environment which is defined as having a radiation level of less than 1.0 x 10 rads (reference 4).

4

3. The subject radiation level of 1.0 x 10 radg is bounded by the threshold dose for generic silicone rubber of 1.3 x 10 rads (Reference 3), and for silicone sealant (Dow Corning 732 RTV) of 7'.0 x 106 (Reference 2).

If Bechtel can be of further assistance, please let us know.

Very truly yours, BE T POWER CORPORATION R.

s

. El a

\ Project Manager Western Power Division NEL/jhc

Enclosures:

Copies of Reference 1 through 4 cc: K. K. Jindal T. M. Khan

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