ML20081G488
| ML20081G488 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 06/03/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20081G481 | List: |
| References | |
| NUDOCS 9106130102 | |
| Download: ML20081G488 (3) | |
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t SAFETY EVALUATION BY lHE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 58 TO FACILITY OPERATING LICENSE NO. NPF-47 GULF STATES UTILITIES COMPANY j
RIVER BEND 51 ATION, UNIT 1 DOCKET NO. 50-458 l
l
1.0 INTRODUCTION
i By letter dated March 12, 1991, Gulf States Utilities Company (G5U) (the licensee) requested an amendment to Facility Operating License No NPf-47 for tha River Bend Station, Unit 1.
The proposed amendment would modify Technical Specification (TS) 3.6.2,3 "Drywell Air Locks" to allow the use of the drywell i
air lock in Operational Condition 3 for up to 7 days with one of the two air lock doors inoperable.
On two separate occasions, G5U had requested waivers of compliance f rom T5 3.6,2,3 when the drywell air lock was declared inoperable due to failure of the inner air lock door seal to meet leakage criteria.
While the door was inoptrable, G5U found it necessary to enter the drywell while the plant was in hot ttandby for the purpose of locating and repairing leakage from the reactor coolant system, This is not in compliance with the T5 which requires that the operable air lock door be locked closed or the plant be in cold shutdown.
l The NRC staff concluded that relief from this requirement would not result in undue risk to the health and safety of the public and granted I
temporary waivers of compliance on February 17, 1989 and again on December 12, l
1990, which allowed entry into the drywell for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> while in Operational Condition 3.
As a condition of the second waiver of compliance, CSU agreed to submit a request for a permanent change to the TS.
i 2.0 EVALUATION t
Technical Specification 3.6.2.3 ACTION a. currently requires that if one of the drywell air lock doors becomes inoperable, the operable door must be locked closed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and operation may continue providing the operable door is verified to be locked closed o me every 31 days.
The purpose of this requirement is to maintain the integrity of the drywell and avoid bypassing large amounts of radioactive steam or air to the contain-ment in the event of a Loss-of-Coolant Accident (LOCA) inside the drywell.
l As a result of this requirement, the plant must be brought to a cold shutdown l
whenever a drywell air lock is inoperable and personnel must enter for I
maintenance work or to repair the inoperable air lock door.
Shutting down
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and then restarting the reactor places extra thermal transients on the plant.
In addition, any work wr.ich involves the identification of reactor coolant
(
system leaks can be performed much more effectively when the reactor is at i
rated pressure.
9106130102 ?t0603 l
PDR ADOC K 00000458 P
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1 The safety analysis for drywell bypass leakage assumes a 1.0 square foot (ft )
?
opening and a small break LOCA in the drywell at a pressure differential of 3 pounds per square inch differential (psid). An opening of 1.0 ft? would result in a flow rate of approximately 40,110 standard cubic feet per minute (SCFM).
This is the design capability of the Mark Ill containment for steam bypass from the drywell to the suppression pool air volume as per the Standar,d Review Plan Section 6.2.1.1.r.
The allowable drywell bypass leakage limit specified in the TS is 10 p'<.ent of the containment capability or 4011 SCFM. While the operable do-is open for essential passage through the air lock, drywell integrit, depends upon the inoperable door seal.
The calculated bypass flow, assuming the operable door is open and both inoperable door seals are deflated, is 12,530 SCFM.
Therefore, the worst case leakage is greater than the TS limit, but well within the safety analysis assumption. The proposed amendment would allow the air lock to be used only af ter the reactor is suberitical (Operational Condition 3) as opposed to the safety analysis assumption in which the reactor is in normal opeiation and must first scram as a result of high drywell pressure.
Thus, the stored energy would be less and reactor depressLr-ize ion would occur sooner than assumed in the safety analysis.
Finally, the drywell unit coolers, which were not taken credit for in the safety analysis, would be in operation during entries into the drywell and would significantly reduce drywell pressure and thus drywell bypass leakage. Additional actions in the proposed amendment would help minimize the total bypass leakage.
These consist of assigning an individual to assure that both doors in the air lock are not open simultaneously and verifying that the operable air lock door is locked after each entry and subsequent exit.
The NRC staff has reviewed tht licensee's cubmittal and has found that access through the drywell air lock for short periods of time when one of the air lock doors is inoperable does not pose an additional safety hazard.
Based on its evaluation, the staff also finds that the proposed chenge is in accordance with the Standard Review plan Section 6.2.1.1.c.
The.efore, the proposed addition to ACTION a. of TS 3.6.2.3 is acceptable,
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Louisiana State official was notified of the proposed issuance of the amendment.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment 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.taff has determined that the amendment involves no significant increase in tha amounts, and no significant change in the types,
3 uf any effluents that moy be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Comission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and thert has been no public comment on such finding (56 FR 20040). Accordingly, the amendment meets the eligibility criteria for categ)orical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSJON The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Comission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principt.1 Contributor:
Donna Slay, PD IV-2 Date:
M 3,1991 1
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