ML20010F791

Part 21 Rept Re Effects of Spurious Opening of Turbine Bypass Sys Valves on Nuclear Supply Sys.Potential Single Active Failure Could Result in Possibility of Exceeding DNBR Limits

ML20010F791
Person / Time
Site:	Davis Besse, Oconee, Arkansas Nuclear, North Anna, Crystal River, Rancho Seco, Midland, Bellefonte, 05000514, 05000515, Washington Public Power Supply System, Crane
Issue date:	08/27/1981
From:	Taylor J BABCOCK & WILCOX CO.
To:	Stello V NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
REF-PT21-81-492-000 PT21-81-492, PT21-81-492-000, NUDOCS 8109110337
Download: ML20010F791 (3)

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Babcock & Wilcox Nuclear Power Generation Division a McDermott company 3315 Old Forest Road P.O. Box 1260 Lynchburg, Virginia 24505 (804) 384-5111 Aug. 27,1981 g

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<f 1 *'bg gI"' y - *)w-Mr. Victor Stello, Jr., Director Office of Inspection and Enforcement b

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Dear Mr. Stello:

This letter is intended to clarify the status of Babcock & Wilcox plants for a potential safety concern that deals with the effects of spurious opening of turbine bypass system valves on the B&W Nuclear Supply System (NSS). This clarification seems appropriate in view of several telephone calls frem the Region II office of Inspection ~and Enforcement in Atlanta, Georgia to Babecek and Wilcox Company on this subject. We believe it to be in the best interest of all concerned that va m srice the :tatus of all Bt'..' plants for thi:

Concern.

Specifically the concern is that a potential single active failure in the steam pressure sensing instrumentationor the NSS control circuitry could cause the spurious opening of turbine bypass system (TBS) valves, resulting in the possibility of exceeding DNBR limits.

177 FA Plants Duke Power Company Oconee 1, 2, & 5 Operating Arkansas Power & Light ANO-1 Cperating Florida Power Corp.

Crystal River 3 Operating General Public Utility TMI-1 & 2 Operating /Chutdown Sacramento Municipal Utility Diacrict Rancho Seco Operating Toledo Edison Co.

Davis Besse 1 Operating Consumers Power Corp.

Midland 1 & 2 Under Construction Because of the variation in the design of these plants, particularly in the seconds.ry system, B&W could not evaluate this concern and there-I fore has turned the evaluation of reportability of the concern over to i

the individual utilities.

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Babcock &Wilcox Mr. Victor Stello Aug. 27, 1981 1h5 FA Plant Virginia Electric Power Co.

North Anna 3 Under Construction B&W has turned this concern over to VEPCo for completion under Section 21.21 of 10 CFR 21 with the following recoumendation:

"B&W reco= mends that you revicv your plant's specific installation for the possibility of a single failure ceising the occurrence and determine what action is necessary te splete the evaluation I

of the concern. As an alternate to review of plant specific infor-mation and evaluation of reportability at this time, you may wish to report this to the NRC as an unresolved safety concern and delay analysis, evaluation of reportability and/or design change imple~

mentation until an active construction schedule is resumed."

VEPCo has since resumed an active construction schedule. On March 9, 1981 they reported this concern to the Region II Office of Inspection and Enforcement as a potential safety concern that vill be resolved in the on-going analysis and design of their plant.

20) FA Plants Tennessee Valley Authority Bellefonte 1 & 2 Under Construction Washington Public Power WNP 1 & h Under Construction Supply System Portland General Electric Pebble Springs No construction Permit or active Construction Schedule For the TVA and Supply System plants, analysis has been performed that indicates these plants may exceed DNBR limits for spurious openir.g of turbine bypass valves that result in steam flows beyond 28%. Limitation of spurious opening of steam dump valves was discussed in TVA's & Supply System's replies to Mr. H. R. Denton's show cause letter of October 25, 1979, "10 CFR 50.5h Request Regarding the Decign Adequacy of Babcock & Wilcox Nuclear Steam Supply Systems Utilizing Once Through Steam Generators."

These plants are in the process of determining what hardware vill best limit spurious opening to 25% + 3% of turbine bypass capacity.

For the Portland General Electric contract, we have turned the evaluation of reportability of this concern over to them for completion under Section 21.21 of 10 CFR 21 with the same recommendation as quoted

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above for the VEPCo plant.

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i Babcock &Wilcox Mr. Victor Stello Aug. 27, 1981 j

The above status eux:ar/- covers all B&W cperating planto and all i

B&W NSS's tuider contract. If we can be of further help in this matter, i

please contact me.

t Very truly yours, ff(?g et-i T. H. Taylor Manager, Licensing i

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Mr. James. P. O'Reilly - Region II Mr. Robert H. Engelken - Region V i

Mr. Robert B. Borsum - B&W Bethesda I

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