05000327/LER-2002-001, Re Nonconservative Low-Level Steam Generator Level Setpoints
| ML021060499 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/12/2002 |
| From: | Purcell R Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RIS-01-005 LER 02-001-00 | |
| Download: ML021060499 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor |
| 3272002001R00 - NRC Website | |
text
April 12,2002 U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:
TENNESSEE VALLEY AUTHORITY - SEQUOYAH NUCLEAR PLANT (SQN)
UNITS 1 AND 2 - DOCKET NOS. 50-327 AND 50-328-FACILITY OPERATING LICENSES DPR-77 AND 79 - LICENSEE EVENT REPORT (LER) 50-327/2002001 The enclosed report provides details concerning nonconservative low-low steam generator level setpoints.
This event is being reported, in accordance with 10 CFR 50.73(a)(2)(i)(B), as an operation prohibited by technical specifications and 10 CFR 50.73(a)(2)(v)(A), as a condition that could have prevented the fulfillment of a safety function. This letter is being sent in accordance with NRC RIS 2001-05.
Sincerely, Original signed by Richard T. Purcell Enclosure cc (Enclosure):
INPO Records Center Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, Georgia 30339-5957
Abstract
On February 15, 2002, Sequoyah performed an assessment of the narrow range steam generator level measurement instrument channels, based on a Nuclear Safety Advisory Letter from Westinghouse Electric Corporation. This assessment determined that the demonstrated accuracy calculation for low-low level trip setpoint narrow range span did not account for the measurement bias associated with the differential pressure (dP) created by the steam flow past the mid-deck plate in the moisture separator section of the steam generators. This dP phenomena could cause the steam generator narrow range level channels to read higher than actual water level at high steam flows. This could cause the low steam generator level trip setpoint to be nonconservative. The cause of the condition was the failure of Westinghouse personnel to account for the measurement bias, when establishing the low-low steam generator level setpoint calculation.
TVA will modify the steam generator setpoints, as applicable, to account for the identified condition.
NRC FORM 366 (7-2001)
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)VII.
ADDITIONAL INFORMATION
A.
Failed Components:
None B.
Previous LERs on Similar Events:
A review of previous reportable events for the past three years did not identify any previous events.
C.
Additional Information
None D.
Safety System Functional Failure:
This condition is considered to be a safety system functional failure in accordance with NEI 99-02, because of the low-low steam generator setpoints being nonconservative.
VIII.
COMMITMENTS
None.