ML20249A755
| ML20249A755 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/11/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20249A752 | List: |
| References | |
| NUDOCS 9806180190 | |
| Download: ML20249A755 (4) | |
Text
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UNITED STATES g
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 3000H001 4,.....
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 223 TO FACILITY OPERATING LICENSE NO. NPF-3 TOLEDO EDISON COMPANY CENTERIOR SERVICE COMPANY b.ND THE CLEVELAND ELECTRIC ILLUMINATING COMPANY DAVIS-BESSE NUCLEAR POWER STATION. UNIT NO. 1 DOCKET N0. 50-346
1.0 INTRODUCTION
By letter dated August 26, 1997, Toledo Edison Company, Centerior Service Company, and The Cleveland Electric Illuminating Company (the licensees),
submitted a request for changes to the Davis-Besse Nuclear Power Station, Unit No.1, Technical Specifications (TSs).
The proposed amendment would revise Technical Specification (TS)
Section 3/4.6.1.3, " Containment Systems - Containment Air Locks," and the associated bases. The limiting condition for operation and the surveillance requirements would be modified. The application also proposed a change to TS Bases 3/4.9.4, " Refueling Operations - Containment Penetrations." That bases change was approved by NRC letter dated March 19, 1998.
2.0 EVALUATION The licensees have proposed changes to TS 3.6.1.3, TS 4.6.1.3 and TS Bases 3/4.6.1.3.
Each proposed change is evaluated below.
2.1 TS 3.6.1.3, " Containment Systems - Containment Air Locks - Limiting Condition for Operation" TS 3.6.1.3 currently reads:
3.6.1.3 Each containment air lock shall be OPERABLE with:
a.
Both doors closed except when the air lock is being used for normal transit entry and exit throuah the containment, then at lesst one air 1cck door shall be closed, and t
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An overall air lock leakage rate of s 0.002 L, at P,, 38 psig.
The licensees are proposing to delete the words " normal transit" and "throuah the containment," so the TS would read:
3.6.1.3 Each containment air lock shall be OPERABLE with:
a.
Both ' doors closed except when the air lock is being used for entry and exit, then at least one air lock door shall be closed, and b.
An overall air lock leakage rate of s 0.002 L, at P, 38 psig.
Each containment air lock forms part of the containment pressure boundary.
The air lock safety function is to provide part of the control of containment leakage resulting from a design basis accident. Therefore, the structural integrity and leak tightness of each air lock are essential to the successful mitigation of such an event. The doors of each air. lock are interlocked to prevent simultaneous opening.
Closure of a single door in each air lock is sufficient to provide a leak tight barrier following postulated events. However, both doors are normally kept closed except when the air lock is being used for entry into and exit from containment, for maintenance or for testing.
Removal of the words " normal transit" eliminates a possible source of confusion in the TSs without changing the meaning.
Therefore, the change is administrative only and is acceptable.
Removal of the words "through the containment" clarifies the inteni, of the TS that air lock maintenance and testing (that is, tasks that do not necessarily require entry into and exit from the containment) can be performed without entering the associated action statement. This clarification does not change the meaning of the TSs.
Therefore, it is also administrative only and is acceptable.
2.2 TS 4.6.1.3, " Containment Systems - Containment Air Locks - Surveillance Requirements [fRs]"
TS SR 4.6.1.3.c currently reads:
Each containment air lock shall be demonstrated OPERABLE:
c.
At least once per 6 months. by verifying that only one door in each l
air lock can be opened at a time.
l The licensees are proposing to delete the words "6 months" and replace them with the words "'tEFUELING INTERVAL." The proposed SR would read:
Each containment air lock shall be demonstrated OPERABLE:
c.
At least once per REFUELING INTERVAL by verifying that only one door in each air lock can be opened at a time.
. Satisfactory perfe"wne of this SR ensures that each interlock is able to l
- Satisfactory performance of this SR ensures that each interlock is able to prevent simultaneous opening of the doors. The proposed revision would extend
'the surveillance interval from once per 6 months to once per refueling interval (defined at Davis-Besse as less than or equal to 730 days).
Currently, each interlock is installed after each refueling outage and verified operable with this SR.
Then, every 6 months the SR is conducted.
This requires that the interlocks be challenged during plant operation.
If the proposed change is approved, the test would be conducted with the plant shut down, when the interlocks are not required to be operable, so that they would not be challenged during plant operation.
If the need for interlock maintenance arises when an interlock is in service, the performance of the interlock SR would be required following the maintenance. When an air lock is opened when the interlock is required, the operator first verifies that one door is completely shut before attempting to open the other door.
Therefore, an interlock is not challenged except during the actual testing of the interlock.
Testing of the interlock mechanism is. accomplished through having one door not completely engaged in the closed position, while attempting to open the second door.
Failure of this test effectively results in a loss of containment 4
integrity.
- A door interlock mechanism cannot be readily bypassed since, as part of bypassing, linkages would have to be removed which are under the control of
. station' processes such as temporary modifications, containment closure procedures and out of service practices.
The licensees reviewed the surveillance records and maintenance history for the previous 10 years. No surveillance test failures were identified.
In addition, no equipment problems occurred that would have rendered an interlock mechanism inoperable.
There is reasonable assurance that each interlock will perform its safety j
function for the extended surveillance interval based on the fact that this change would eliminate interlock challenges at power due to regular performance of SR.4.6.1.3.c'(as each interlock is only challenged during i
interlock testing), the mechanical design of the interlock is difficult to defeat, historical data confirm the reliability of the interlocks, and air i
lock doors are operated under specific administrative controls. Therefore, the staff concludes.that the extension of the SR testing interval from 6 months to each refueling interval (730 days) is acceptable.
j i
2.3 TS Bases'3/4.6.1.3, " Containment Air Locks" The licensees are proposing to add the following text to TS Bases 3/4.6.1.3:
The air lock interlock allows only one air lock door of an air lock to be opened at a time. This provision ensures that a gross breach of containment'does not exist when CONTAINMENT INTEGRITY is required.
Closure of a single door in each air lock is sufficient to provide a i
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leak tight barrier following postulated events.
Nevertheless, in MODES.
I through 4, t,oth doors are kept closed when the air lock is not being used for entry and. exit, i.e., containment entries / exits, air lock maintenance, or air lock testing.
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This addition will add clarifying information consistent with the current TSs and operations at Davis-Besse.
Therefore, it is acceptable.
3.0 STATE CONSULTATION
In accordance with the Comission's regulations, the Ohio State official was notified of the proposed issuance of the' amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
This 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 or changes a surveillance requirement. -The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluent that may 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 there has been no public comment on such finding (62 FR 54876). Accordingly, the amendment meets the eligibility criteria for categorical 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 CONCLUSION
The staff 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 this amendment will not be inimical to the comon
- defense and security or to the health and safety of the public.
Principal Contributor:
A. Hansen Date:
June 11, 1998 7.
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