ML20094M282
| ML20094M282 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 03/23/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20094L896 | List: |
| References | |
| NUDOCS 9203300269 | |
| Download: ML20094M282 (3) | |
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UNITED STATES 8 $# ')
NUCLE AR REGULATORY COMMISSION
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SATETY EVALVATI0fLBY THE OFFICE OF NELLAR REACT 0R REGVdllM RELATED TO AMENDMENT NO. ca TO FACILITY OERATING LICENSE NO. NPF-23 ENTERGY OPERATIONS. INC.. ET At.
4 GRA@_(MLF_RQC.LLAR STATION. UNIT 1
@LKJT NO. 50-416 1.0 INTRODUCT10jj By letter dated February 27, 1991, the licensee (Entergy Operations, Inc.),
submitted a request inr changes to the Grand Gulf Nuclear Station, Unit 1 License.
The requested changes would replace current License Condition 2.C(36), Attachment 1, Jtem (c)(4), which requires implementation of the requirements of Regulatory Guide (RG) 1.97 for flux monitoring prior to startup following the fifth refueling outage.
The proposed new license condition would allow implementation of the RG 1.97 flux monitoring to be deferred until after the NRC staff has finished reviewing the BWR Owners' Group (BWROG) appeal of the RG 1.97 requirements.
2.0 EVALVATIM The post-accident neutron monitoring system is intended to warn that the reactor is returning to a critical state.
Under anticipated design Lusis events, a return to a critical state would not be expected once all the rods have been inserted, However, in certain hypothetical situations, rods could drift out or fuel could undergo physical changes, in these cases, the proposed system would provide 8 accades (10E-6i' tc 100% power) of power status information, allowing the approach to criticality to be detected over a greater operating range.
The earlier warning would give the operators more time to initiate mitigative actions.
The current margin of safety is established by the existing operhting neutron monitoring system and the shutdown margin of the control rod system.
The post-accident monitoring system required by RG 1.97 provides additional information for the operator to respond to undefined post-accident reactivity anomalies. Until the post-accident qualified neutron flux monitoring system is installed and opecational, the licensee will continue to use the presently installed neutron flux monitoring system and other post-accident qualified Instrumentation.
The presently installed system is expected to indicate subcritical reactor power during the initial phase of an accident (including a LOCA).
Long-term moni?oring is available through the the APRM channels where 9203300269 920333 PDR ADOCK 05000416 p-PDR
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, operator action is required at the APRM down scale alarm. However, because of Category I requirements, long-term direct monitoring in a harsh environment may not be available over the entire RG 1.97 range.
In that event, other provisional measures and indications are available to the operator:
(a) The present control rod position indication system provides the reactor operator with the information that all rods are inserted.
(b) Qualified instrumentation, such as for reactor pressure, suppression pool temperature, and safety relief valve actuation, provides 'he reactor operator with post-accident information to assess reactor power if direct neutron monitoring capability is not available.
(c) The Emergency Procedures (EP) are symptom-based and provide appropriately conservative actions if reactor power cannot be directly measured in a post-accident situation.
The EP contain action steps that mitigate the symptomatic effects of design basis events (such as LOCA) and events beyond design basis events (such as ATWS).
These compensatory measures ensure that the consequences of an accident previous!y evaluated will not be significantly increased by thn absence of a a
post-accident neutron flux monitoring '.vstem while the NRC staff completes its review of the BWROG appeal of RG 1,/ requirements.
Based on the above evaluation, the staff conclude = tnat the existing neutron flux monitoring instrumentatien is acceptable fo' interim use. The staff expects the licensee to comply with the resolution of the BWROG appeal.
3.0 11 ATE CONSULTAT10t1 In accordance with the Commission's regulations, the Mississippi State official was notified of the proposed issuance of the amendment.
The State official had no comments.
4.0 My_lE0NG NTAL CONSIDERATION The amendmer,t changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR-Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (57 FR 6037).- Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR St.22(b), no environmental im>act statement or enviroraental assessment need be prepared in connection wit1 the issuance of the amendment.
3-5.0 C0f1CLUS10f1 The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonabic assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) ;urh activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendmelit will not be inimical to the common defense and security or to the health and safety of the public.
Principal ContribJtor:
M. Sykes P. O'Connor Date: March 23, 1992 e
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