ML20237F217
| ML20237F217 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 08/17/1998 |
| From: | Swailes J NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS980137, NUDOCS 9809020131 | |
| Download: ML20237F217 (3) | |
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Nebraska Public Power District e
Nebraska's Energy Leader August 17,1998 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Gentlemen:
Subject:
Revision of Commitment Made in Response to Unresolved Items Cooper Nuclear Station, NRC Docket 50-298, DPR-46
Reference:
- 1. Letter to U. S. Nuclear Regulatory Commission from P. D. Graham (NPPD) dated January 15,1998, " Follow-up Information Relative to Unresolved Items Identified in NRC Inspection Report 97-18"
December 17,1997, "NRC Inspection Report 50-298/97-18" By letter dated January 15,1998 (Reference 1), responding to a Nuclear Regulatory Commission (NRC) Inspection Report (Reference 2), Nebraska Public Power District (District) committed to j
revise the 125 Vdc load and voltage studies by August 31,1998. In Reference I the District
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identified a number of actions that were being pursued to update the studies which included-l A representative sample ofcircuits will be validated to assure a high level of confidence in the inputs to be used 1his representative sample will be expanded, as appropriate, j
based on the number andsignificance ofany errorsfound
- y The existing calculations are based on a single scenario that superimposes the loads of Station Bhick Out (SBO), Appendix R, andLoss of Coolant Accident - Loss of Off-site Power (LOCA-LOOP). This approach has beenfcmnd to be overly conservative, difficult to maintain, and somewhat confusing. Accordingly, this single scenario will be j
l separated into individual scenarios specific to the requirements being addressed 1he basisfor the sequencing of events in each scenario will be validated and documented."
Validation of a 20 percent sampling of 125 Vdc circuits and the scenario separation effort has taken longer than originally scheduled. Additionally, the validation sample size is being increased 9809020131 980817 PDR ADOCK 050002981 P
PDR.
Luuper Nudear Station t.v -
Po. Box 98/ Brownville. NE 68321D098 Telephone: (402) 825-38H / Fax: (402) 825-52n http //www.nppd com
NLS980137 August 17,1998 Page 2 to include redundant circuits to those where adverse anomalies were noted. Difficulties in locatirejand retrieving component specific information to support the circuit validation effort have contributed to project delays. Revised schedules have been provided by the Contract Engineers performing the evaluations and a new overall project schedule prepared for the remaining activities. Consequently, the 125 Vdc load and voltage studies will be revised prior to November 20,1998.
Preliminary results of work completed to date indicates that the presumptions made in the November 1997 Operability Assessment remain valid. Consequently the battery remains capable of performing its safety function.
Should you have any questions concerning this matter, please contact me.
Sincerely, J.
-I.
'a'es Vi e Pr entlof Nuclear Energy
/nr cc: Regional Administrator USNRC - Region IV Senior Project Mar ager USNRC - NRR Project Directorate IV-1 Senior Resident Inspector USNRC NPG Distribution I
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l ATTACHMENT 3 LIST OF NRC COMMITMENTS l
4 l
Correspondence No:
NLS980137 The following table identifies those actions committed to by the District in this document.,Any other actions discussed in the submittal represent intended or l
planned actions by the District. They are described to the NRC for the NRC's l information and are not regulatory commitments.
Please notify the NL&S Manager at I
Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
1 COMMITTED DATE COMMITMENT OR OUTAGE CNS will revise the 125 Vdc load and voltage studies.
November 20, 1998 l
l PROCEDURE NUMBER 0.42 l
REVISION NUMBER 6 l
PAGE 9 OF 13 l
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