L-98-162, Provides Clarification of Response Contained in Licensee Re NRC SER on BVPS Implementation of ATWS Rule. Ltr Modifies & Supersedes .Encl Info Supports Conclusion Previously Transmitted in Licensee
| ML20236Y260 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 08/04/1998 |
| From: | Jain S DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| L-98-162, TAC-MA0715, TAC-MA0716, TAC-MA715, TAC-MA716, NUDOCS 9808120033 | |
| Download: ML20236Y260 (2) | |
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=O "2. en August 4,1998 L-98-162 U. S. Nuclear Regulatory Commission j
Attention: Document Control Desk Washington, DC 20555-0001 l
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Subject:
Beaver Valley P9wer Station, Unit No.1 and No. 2 BV-1 Docket No. 50-334, License No. DPR-66 BV-2 Docket No. 50-412, License No. NPF-73 NRC Safety Evaluation Report -Implementation of ATWS Rule This letter modifies and supersedes Duquesne Light Company (DLC) letter L 140, dated July 9,1998. This letter provides a clarification of the DLC response to question I contained in letter L-98-140 in accordance with a verbal NRC staff request.
DLC letter L-98-140 provided the response to NRC Request for Additional Information l
letter, dated May 7,1998, regarding Duquesne Light Company's comments on NRC Safety Evaluation concerning Beaver Valley Power Station-Unit Nos. I and 2 implementation of the Anticipated Transient Without Scram rule (TAC Nos. MA0715 l
and MA0716). The issue involves an inconsistency between the NRC Safety Evaluation Report (SER) supplied for Beaver Valley Power Station Unit 1 & 2 on the Implementation of the ATWS Rule, dated May 31,1988, and the design of the ATWS Mitigating System Actuation Circuitry (AMSAC) submitted by DLC to meet 10 CFR l 50.62 criteria, as required by 10 CFR 50.62(C)(6).
The attached information supports the conclusion previously transmitted in the DLC [[letter::L-97-065, Discusses Inconsistency Between NRC SER Supplied to Util on Implementation of ATWS Rule & Design of ATWS AMSAC Submitted by Util,Per 10CFR50.62|letter dated January 5,1998]], that
- 1) the design inasis for the current C-20 l
permissive has been consistently described as based on a nominal turbine loading setpoint, as described in WCAP-10858-P-A, 2) the 30% margin between the C-20 setpoint and the initial power level of 70% established by ATWS analyses where AMSAC is needed is sufficient to offset any reasonable power variations due to measure ment uncertainties, and 3) the Beaver Valley Power Station AMSAC design for the C-26 permissive is acceptable based on a nominal setpoint of 40% turbine load.
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ENERGV 9808120033 980804
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Beaver Valley Power Station, Unit No. I and No. 2 NRC Safety Evaluation Report - Implementation of ATWS Rule Page 2 If you have any questions concerning this response, please contact Mr. S. Hobbs, Director, Safety & Licensing Department at (412) 393-5203.
Sincerely, Sushil C. Jain c:
Mr. D. M. Kern, Sr. Resident Inspector Mr. H. J. Miller, NRC Region I Administrator Mr. D. S. Brinkman, Sr. Project Manager
2 Reauest for AdditionalInformation Question No.1:
DLC's [[letter::L-97-065, Discusses Inconsistency Between NRC SER Supplied to Util on Implementation of ATWS Rule & Design of ATWS AMSAC Submitted by Util,Per 10CFR50.62|January 5,1998, letter]] stated that VR :tinghouse had recently reconfirmed, in Westinghouse Technical Bulletin ESBU-TB-08, that an initial condition of 50% reactor power would be acceptable.
Please inform us whether DLC has determined if Westinghouse Technical Bulletin ESBU-TB-08 is applicable to BVPS-1 and BVPS-2 and ifit is acceptable.
DLC Response: DLC has confirmed that Westinghouse Technical Bulletin ESBU-TB-08 is spplicable to BVPS-1 and BVPS-2, as stated in tids Westinghouse correspondence. DLC also agrees with the Westinghouse Technical Bulletin recommendation to maintain the C-20 AMSAC pennissive based on a turbine-impulse pressure corresponding to 40% turbine power. In addition, DLC has confirmed that WesdaN Technical Bulletin ESBU-TB-08 is acceptable for BVPS-1 and BVPS-2.
l Question No. 2:
DLC's [[letter::L-97-065, Discusses Inconsistency Between NRC SER Supplied to Util on Implementation of ATWS Rule & Design of ATWS AMSAC Submitted by Util,Per 10CFR50.62|January 5,1998, letter]] also stated that a review of data from the last startup of BVPS-1 and BVPS-2 indicated a discrepancy of l
about 3% between reactor power and turbine load at 40% reactor power. Please provide additional information regarding other instances of noted discrepancies between reactor power and turbine load during other startups.
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DLC Response: The following data was obtained for BVPS Unit I startups from the plant computer:
M Delta Between Calorimetric Power and Turbine Load 1/23/98 Oscillated between 2-3% near 40%
8/10/97 Oscillated between 2-4% near 40%
7/31/97 Oscillated between 1-4% near 40%
The BVPS Unit 2 plant computer does not have the capability to directly download this type ofinformation. The following information was conservatively calculated from the Unit 2 plant data available during startups and shutdowns:
M Delta Between Calorimetric Power and Turbine Load 4/13/97 5.8%(shutdown @ 38%)
4/15/97 5.3% (startup @ 40%)
7/10/97 5.2%(shutdown @ 44%)
7/24/97 2.9%(startup @ 39%)
12/16/97 5.1%(shutdown @ 42%)
The above data confirms the statement in the Westinghouse Technical Bulletin that the differences between turbine power and reactor power (near 40%) may vary on the order of 5% to 10% of nominal power.
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