ML19309F107
| ML19309F107 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 04/03/1980 |
| From: | Dale L MISSISSIPPI POWER & LIGHT CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| AECM-80166, NUDOCS 8004280501 | |
| Download: ML19309F107 (3) | |
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I MISSISSIPPI POWER & LIGHT COMPAN.Y Helping Build Mississippt
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5 P. O. B OX 164 0. J AC K S O N MIS SIS SIP PI 3 9 205 r
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PRODUCTIO N DEP A RTM E NT
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Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N.W., Suite 3100 Atlanta, Georgia 30303 ATTN:
Mr. J. P. O'Reilly, Director
Dear Mr. O'Reilly:
SUBJECT:
Grand Gulf Nuclear Station
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Units 1 and 2 Docket Nos. 50-416/417 File 0272/15525/15526 PRD-80/04, Effects of Loss of Site Power on Rod Position Indication and Neutron Monitoring Indication AECM-80/66 On March 4,1980, Grand Gulf Nuclear Project Management was notified of a Potentially Reportable Deficiency (PRD) concerning the Loss of Site Power (LOSP) accident and its attendant effects on the Rod Position Information System (RPIS) and Neutron Moni-toring System (NMS). An investigation into this deficiency was commenced immediately. On March 5,1980, Nuclear Project Manage-ment concluded that this matter, while operationally undesirable,
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was not reportable under 10 CRF 50.55(e).
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On March 17, 1980, this matter was presented to Mr. F. Cantrell of your office for information purposes. During that telephone communication, Mr. Cantrell expressed his opinion that the matter was a reportable condition as described in 10 CIF 50.55(e). At that time, Mississippi Power & Light agreed to trocess this matter as a potentially reportable deficiency. Even th) ugh Mississippi Power & Light held that the deficiency was not r. portable, the issue 30/7 1s reopened in view of our discussion with Mr. Cantrell. We are currently re-evaluating our position and rationale on the reporta-bility of this deficiency.
3 OFF7CIAL COPI Member Middle South Utilities System 8004280 h O(:
a MISSISSIPPI POWER & LIGHT COMPANY Cffice of Inspection & Enforcement AECM-80/6f U. S. Nuclear Regulatory Commission Page two We expect to provide our determination and final report on this issue by May 21, 1980. An overview summary of this deficiency is attached.
Yours truly, Y
L. F. Dale Nuclear Project Manager JGC/JDR:ts Attachment cc:
Mr. T. B. Conner Mr. R. B. McGehee Mr. Victor Stello, Jr., Director Division of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
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8 Attachment to AECM-80/66 Overview of Deficiency PRD-30/04 During a recent review of Regulatory Guide 1.97, an issue was raised regarding the lose of certain instrumentation following a Loss of Site Powet (LOSP) event The LOSP ev nt is one of many postulated e
operational transients which have been analyzed and evaluated for their consequences to the safe operation of Grand Gulf Nuclear Station (GGNS). This particular event is discussed in detail in Chapter 15 of our Final Safety Analysis Report and is categorized as an incident of moderate frequency, i.e., an anticipated operational transient.
With the LOSP event, power is lost to the Reactor Protection System (RPS) motor generator (m-g) sets which are classified in the FSAR as non-essential. These m-g sets provide power to the RPS busses which in turn primarily feed the RPS trip channels, the Neutron Monitoring System (NMS), and Process Radiation Monitoring (PRM) System channels. Along with the loss of power to the RPS m-g sets, power supply is also lost to the Rod Control and Information System (RCIS).
All instrumentation listed above is initially shed in the LOSP event, but power can be restored from the standby diesel generators.
The restoration of power to them is not automatic but requires operator action.
The restoration of power to this instrumentation is not an operator action required for plant safety. The safety analysis for CGNS takes no credit for having power to this instrumentation. All protective actions required to place the plant in a safe shutdown condition are automatic features designed such that no operator action is required for the first ten minutes of the transient or upset condition.
In the case of the LOSP event, the attendant loss of the above mentioned instrumentation does not preclude the initiation of the automatic protective features. These features function to scram the reactor, remove decay heat, keep the reactor core covered, and place the plant in a safe condition. Some of these features that operate or occur during a response to an LOSP event are:
turbine control valve closure, main turbine bypass system operation, recirculation system pump motors trip, reactor scram, safety relief valve operation, main steam isolation valve closure, High Pressure Coolant Spray (HPCS) system operation, and Reactor Core Isolation Cooling (RCIC) system operation.
This overview of the issue does not constitute our final evalu-ation. The loss of neutron monitoring and rod position information is regarded as operationally undesirable but not unsafe. Our final evaluation will include our determination on the reportability of the issue and corrective actions proposed to address the deficiency.
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