ML20195G439
| ML20195G439 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 06/11/1999 |
| From: | Muench R WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ET-99-0024, ET-99-24, IEIN-97-015, IEIN-97-15, NUDOCS 9906160060 | |
| Download: ML20195G439 (3) | |
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W@ NUCLEAR OPERATING LF CREEK 1-Richard A. Muench Vice President Engineering JUN 111999 ET 99-0024 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station"P1-137 Washington, D. C.
20555
Reference:
1)
Letter WM 95-0052, dated March 22, 1995, N.
S. Carns, WCNOC, to NRC 2)
Letter WM 94-0061, dated March 31, 1994, N. S. Carns, WCNOC, to NRC 3)
Letter ET 99-0013, dated March 17, 1999, R. A. Muench, WCNOC, to NRC i
Subject:
Docket No. 50-482:
10 CFR 50.46 Thirty Day Report of ECCS Model Revisions Gentlemen:
In response to the concerns raised in NRC Information Notice IN 97-15, j
Supplement 1,
Wolf Creek Nuclear Operating Corporation (WCNOC) reviewed l
reports submitted since 1993 under 10 CFR
- 50. 4 6 (a) (3) (1) and (ii),
as clarified in Section 5.1 of WCAP-13541,
" Westinghouse Methodology for
- _;iementation of 10 CFR 50.46 Reporting," for the Wolf Creek Generating
)
Station (WCGS).
Since 1993, WCNOC has submitted two 30-day reports and six annual reports.
However, during our recent review, we identified one instance i<
in which a 30-day report should have been submitted in 1994, but it was not I
identified at the time that a report was required.
This letter provides the details for that missed report.
The WCGS large-break and small-break Loss of Coolant Accidents ;LOCA) were reanalyzed in 1992, using approved Westinghouse Evaluation Models, in support i
of the WCGS Power Rerate.
These reanalyses were submitted to the NRC as part of the Power Rerate License Amendment Request, which was approved by the NRC on March 30, 1993.
These reanalyses replaced the previous analyses and are the current licensing basis analyses for these accidents.
In October 1994, WCNOC received information from Westinghouse concerninc l
deficiency identified in the SBLOCTA code used for the axial nodalization l
the fuel rod.
The SBLOCTA code is a part of the NOTRUMP small break LOCA evaluation model.
A Peak Cladding Temperature (PCT) effect of
+26'F was assessed as a result of this issue.
In addition, Westinghouse also presented l
the assessed PCT effects for two other items concerning the small break LOCA l
model;
-6*F for a boiling heat transfer correlation error, and +18'F for a steam line isolation logic error.
The cumulative PCT effect of these changes equaled exactly. 50'F.
.Since the 50*F 30-day report criterion was not exceeded WCNOC determined a 30-day report was not required.
The information on the nature of ' these changes or errors and their estimated effects on the calculated PCT for the limiting ECCS analysis was described and reported in the subsequent annual report submitted in March 1995 (Reference 1).
9906160060 990611 3
t PDR ADOCK 05000482 l
G PDR RO. Box 4ft / Burlington, KS 66839 / Phone: (316) 364-8831 An Equal Opportumty Ernployer M F<HC' VET L
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n' ET 99-0024 Page 2 of 2 However, it was not identified at the time that a 16'F PCT benefit previously assessed for the LUCIFER code (component database generation) error corrections (reported in Reference 2) should have been included in the determination of the cumulative PCT effect in October 1994.
Including this benefit raises the cumulative PCT effect of model errors and changes in 1994 to 6 6*F, which required a 30-day report to be submitted, per 10 CFR
- 50. 4 6 (a) (3) (ii).
While WCNOC did not identify that a 30-day report was required in October 1994, all ECCS model changes _and errors have been tracked and reported in the annual reports and 30-day reports submitted since 1993.
As reported in the annual report submitted in March 1999 (Reference 3), the current large break LOCA Net PCT is 2 0 81. 2'F, with -a cumulative PCT effect of 15'F, and the current small break LOCA Net PCT is 1607. 6*F, with a cumulative PCT effect of 22*F.
The failure to identify the need for a.'0-day report in October 1994 does not affect the PCT values reported in March 1999.
The current evaluations show that WCGS continues to meet the criteria of 10 CFR 50.46(b).
With respect to SBLOCA, the subject of this report, there is not an immediate need to reanalyze due to the substantial margin to 10 CFR 50.46(b) criteria.
However, WCNOC plans to reanalyze the SBLOCA event for any subsequent major plant change, such as a power rerate or fuel design change, with potential for significantly impacting the SBLOCA event.
AttachmInt I provides a summary of commitments made in this submittal.
If you have any questions concerning this matter, please contact me at (316) 364-4034, or Mr. Michael J. Angus, at (316) 364-4077.
Very truly yours, W
Richar A. Muench 8
RAM /rlr Attachment l
cc:
W.
D. Johnson (NRC), w/a E. W.
Merschoff (NRC), w/a K. M. Thomas (NRC), w/a Senior Resident Inspector (NRC), w/a l
i 1
l tI
Attachment I to ET 99-0024 Page 1 of 1 e
LIST OF COMHITMENTS Th'e following table identifies those actions committed to by Wolf Creek Nuclear Operating Corporation (WCNOC) in this document.
Any other statements in this submittal are provided for information purposes and are not considered to be commitments.
Please direct questions regarding these commitments to Mr.
Michael J.
Angus, Manager Licensing and Corrective Action, (316) 364-4077.
COM4ITMENT Due Date/ Event WCNOC plans to reanalyze the SBLOCA event for any Major plant subsequent major plant change, such as a power rerate change, such as or fuel design change, with potential for a power rerate.
significantly impacting the SBLOCA event.
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