ML20117M835
| ML20117M835 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 09/13/1996 |
| From: | Graham P NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS960173, NUDOCS 9609180124 | |
| Download: ML20117M835 (4) | |
Text
e COOPER NUCLEAR STATION i
P.O. 90X 90. BROWNVILLE. NEBRASKA $8321 4
Nebraska Public Power District AX M ""
I NLS960173 September 13,1996 1
l l
U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Gentlemen:
Subject:
Revision of Commitment Cooper Nuclear Station, NRC Docket 50-298, DF R-46
References:
- 1. NEDO-31558 dated March 1988," Position on NRC Regulatory Guide 1.97, 1
Revision 3, Requirements for Post-Acciden t Neutron Monitoring System"
- 2. Letter to NRC from G. R. H )rn (NPPD) dated June 7,1993, " Cooper Nuclear Station Compliance with NEDO-31558"
- 3. USNPC Generic Letter 94-02 dated July 11,1994,"Long-Term Solutions and Upgrade ofInterim Operating Recommendations for Thermal-Hydraulic Instabilities in Boiling Water Reactors" j
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- 4. Letter to NRC from J. H. Mueller (NPPD) dated December 4,1995, " Cooper Nuclear Station Compliance with NEDO-31558, ' Position on NRC Regulatory Guide 1.97, Revision 3, Requirements for Post-Accident Neutron Monitoring System'"
By lettet; dated June 7,1993 (Reference 2), Nebraska Public Power District (District) committed to implementing a plant modification to relocate the APRM and LPRM card power sources to two redundant uninterruptable power sources to conform with the guidance of NEDO-31558 (Refere..ce 1). By letter dated December 4,1995 (Reference 4), this commitment was integrated with actions being taken in response to Generic Letter 94-02 (Reference 3) and rescheduled from
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the original commitment date of prior to startup from refueling outage RE16 to RE 17. As a result of further evaluation, the commitment to implement the described modification is bemg retracted.
l\\'O Basis for Commitment Change Paragraph 5.2.8 of NEDO-31558 (Reference 1) establishes the alternate requirements necessary to meet the intent of Regulatory Guide 1.97. Specifically, as stated in Paragraph 5.2.8:
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NLS960173.
September 13,1996
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Page 2 0f 3
" Power supplies should be reliable and available during most events in order to avoid
- unnecessary actions in some events such as are described in Section 4.0. They should be
. from uninterruptable sources in order to monitor neutron flux continuously during automatic load shed events, but because of the many alternate methods to establish reactor power (see
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Section 6.0), it is not necessary that Class 1E power be provided."
These requirements are met as described below, i
The Average Range Power Monitors (APRMs) and the Local Power Range Monitors (LPRMs) i are divided into two divisions. Each division is normally powered by a Reactor Protection
~ System (RPS) high inertia motor-generator (MG) set, with each MG set powered from a separate critical bus. During power operation, these critical buses are powered from the Normal Transformer. When this source is unavailable, three alternate feeders are available through automatic, fast transfer breakers. These are, listed in the order of the selection logic:
The Startup Transformer - the normal off-site source, supplied through non-critical buses.
The Emergency Transformer - the back-up off-site source supplied directly to the 4160 VAC critical buses.
The Emergency Diesel Generators (EDGs) - the back-up on-site source. (Note that if power.
is lost to the critical buses and the above sources are unavailable, restoration of power could -
be delayed up to the time required to start and load the Emergency Diesel Generators.)
In addition to the above, each division can be powered by the oter division's supply through a manual break-before-make transfer switch.
Based on the above described configuration, only during a complete loss of off-site power (LOOP) would there be a temporary loss of all APRM and LPRM indication. During this time, reactor status could be determined by the Rod Position Indication System (RPIS). (Power to RPIS is provided by the 250 VDC batteries through the No-Break Power Panel.) Under these conditions, restoration of the APRM and I.PRM indications would be accomplished by:
- 1. Repowering the critical buses by the EDGs (automatic action).
- 2. Manually resetting the electrical protection assemblies (EPAs) and transferring RPS power to the alternate source.
Direction for completing these actions is provided in Abnormal Procedure 2.4.6.12, "RPS Power Supply Failure," and Emergency Procedure 5.2.5, " Loss of Nonnal AC Power - Use of Emergency AC Power."
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1 NLS960173 September 13,1996 Page 3 of 3 In addition, the operators could use the Intermediate Range Monitor (IRM) system to determine core power. The IRM system utilizes detectors that are withdrawn from the core during operation at higher power levels to prevent damage from high neutron flux. The IRM drives are supplied with power from an essential bus through a non-essential distribution panel. The IRM electronics are powered by two 24 VDC battery chargers, supplied from essential buses, which are backed up by redundant 24 VDC batteries. Thus, the IRM system would remain available if a LOOP were to occur. If necessary, the IRMs could be inserted into the core and used as j
another separate and diverse means to confirm reactor shutdown.
In summary, the District is currently in compliance with the requirements of NEDO-31558 as delineated in Paragraph 5.2.8. Therefore, the commitment to implement a plant modification to relocate the APRM and LPRM card power sources to two redundant uninterruptable power sources is being retracted. This position is similar to that presented by Monticello, Fitzpatrick,
. and Brunswick, and approved by the NRC.
Should you have any questions concerning this matter, please contact me.
Sincerely, h
P. D. Graham 1
Site Manager
/crm Attachment ec: Regional Administrator USNRC - Region IV Senior Project Manager USNRC - NRR Project Directorate IV-1 Senior Resident inspector USNRC
- NPG Distribution
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ATTACHMENT 3 LIST OF NRC. COMMITME13TS e
Correspondence No:
NLS960173 The following table identifies those actions committed to by the District in this document. Any other actions discussed.in the submittal represent intended or planned actions by the District.
They are described to the NRC for the NRC's information and r.re not regulatory commitments.
Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
l COMMITTED DATE COMMITMENT OR OUTAGE None.
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l PROCEDURE NUMBER 0.42 l
REVISION NUMBER 1.2 l
PAGE 8 OF 10 l
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