ML20046B550
| ML20046B550 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/23/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20046B547 | List: |
| References | |
| GL-90-06, GL-90-6, NUDOCS 9308050135 | |
| Download: ML20046B550 (4) | |
Text
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NUCLEAR REGULATORY COMMISSION
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 81 TO FACILITY OPERATING LICENSE NO. DPR-80 AND AMENDMENT NO. 80 TO FACILITY OPERATING LICENSE NO. DPR-82 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT. UNITS 1 AND 2 DOCKET NOS. 50-275 AND 50-323
1.0 INTRODUCTION
i On June 25, 1990, the staff issued Generic Letter (GL) 90-06, " Resolution of Generic Issue 70, ' Power-Operated Relief Valve and Block Valve Reliability,'
and Generic Issue 94, ' Additional Low-Temperature Overpressure Protection for Light-Water Reactors,' Pursuant to 10 CFR 50.54(f)." The generic letter represented the technical resolution of the above mentioned generic issues.
Generic Issue 70, " Power-0perated Relief Valve and Block Valve Reliability,"
i involves the evaluation of the reliability of power-operated relief valves i
(PORVs) and block valves and their safety significance in PWR plants.
The generic letter discussed how PORVs are increasingly being relied on to perform safety-related functions and the corresponding need to improve the reliability of both PORVs and their associated block valves.
Proposed staff position and improvement to the plant's technical specifications were recommended to be implemented at all affected facilities. This issue is applicable to all Westinghouse, Babcock and Wilcox, and Combustion Engineering designed facilities with PORVs.
Generic Issue 94, " Additional Low-Temperature Overpressure Protection for Light-Water Reactors," addresses concerns with the implementation of the requirements set forth in the resolution of Unresolved Safety Issue (USI) A-26, " Reactor Vessel Pressure Transient Protection (Overpressure Protection)."
The generic letter discussed the continuing occurrence of overpressure events and the need to further restrict the allowed outage time for a low-temperature overpressure protection channel in operating MODES 4, 5, and 6.
This issue is only applicable to Westinghouse and Combustion Engineering facilities.
By letter dated December 21, 1990, Pacific Gas and Electric Company (or the licensee) responded to GL 90-06. By letter of March 27, 1991, as supplemented October 5, 1992 and July 20, 1993, the licensee submitted a request for changes to the Technical Specifications (TS) in response to GL 90-06.
The October 5, 1992 and July 20, 1993 submittals provided clarifying information that did not change the initial proposeo no significant hazards determination or expand the scope of the original Federal Register notice.
9308050135 930723 PDR ADOCK 05000275 P
. J 2.1 EVALUATION FOR GENERIC ISSVE 70 The technical findings and the regulatory analysis related to Generic Issue 70 are discussed in NUREG-1316, " Technical Findings and Regulatory Analysis Related to Generic Issue 70--Evaluation of Power-Operated Relief Valve and i
Block Valve Reliability in PWR Nuclear Power Plants."
l The TS changes in response to Generic Issue 70 consist of the following changes to TS 3/4.4.4, " Relief Valves:"
1.
The action required with one or more power-operated relief valves 1
(PORVs) inoperable due to excessive seat leakage would be revised
}
to require that power is maintained to the associated closed block valves (s). The current Action Statement does not require power to i
be maintained to the closed block valve (s).
2.
The shutdown requirements would be revised to be consistent with the mode applicability requirements.
l 3.
The action required with one or more block valves inoperable would be revised to delete the option of closing the inoperable block i
valve and removing power from it. This change would eliminate the option for continued operation with a Class 1 PORV block valve i
j 4.
New Surveillance Requirements would be added for the Backup Air / Nitrogen system for the Class 1 PORVs.
I 5.
The block valve Surveillance Requirement would be modified to require operating the valve through one complete cycle of full travel to demonstrate operability when the block valve is closed due to excessive seat leakage of a PORV.
q 6.
Surveillance Requirement 4.4.4.3 has been added to verify the capability of the valves in the safety-related PORV control air systems.
7.
Surveillance Requirement 4.4.4.1.a has been revised to require the 18-month PORV stroke test to be performed during Mode 3 or Mode 4.
Additionally, the GL requests that PORVs be stroked in all cases prior to establishing conditions where the PORVs are used for low-temperature overpressure protection.
This could be interpreted to mean that PORVs should be stroke tested during every shutdown and again during every startup. However, the inclusion of the PORVs in the IST program (also recommended) requires that the valves be tested no more frequently than every three months (unless valve maintenance is performed) to demonstrate operability. The intent of the Generic Letter was not to increase the frequency of PORV i
stroke testing.
8.
The TS Bases would be revised to reflect the proposed changes and to better define the basis for operability of the PORVs and block valves.
The staff has reviewed the licensee's proposed modifications to the Diablo Canyon, Units 1 and 2 Technical Specifications and the associated bases.
Since the proposed modifications are consistent with the staff's position previously stated in the GL and found to be justified in NUREG-1316, the staff finds the proposed changes to be acceptable.
2.2 EVALUATION OF GENERIC ISSUE 94 The technical findings and the regulatory analysis related to Generic Issue 94 are discussed in NUREG-1326, " Regulatory Analysis for the Resolution of Generic Issue 94, Additional Low-Temperature Overpressure Protection for i
Light-Water Reactors."
The TS changes in response to Generic Issue 94 consist of the following changes to TS 3/4.4.9.3, " Overpressure Protection Systems:"
1.
A new Action Statement would be added that reduces the allowed outage time from 7 days to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for an inoperable PORV in Modes 5 or 6.
2.
An Analog Channel Operational Test would be required to demonstrate PORV operability instead of a Channel Functional Test.
3.
The frequency for PORV surveillance would be changed from "within 31 days prior to entering a condition in which the PORV is required Operable" to "at least once per 31 days."
4.
The 15 and Bases would be revised to identify that the TS only applies to the Class 1 PORVs.
The staff has reviewed the licensee's proposed modifications to the Diablo Canyon, Units 1 and 2 Technical Specifications and the associated bases.
Since the proposed modifications are consistent with the staff's position previously stated in the generic letter and justified in'the above-mentioned regulatory analysis, the staff finds the proposed modifications to be acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the California State official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
These amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in i
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10 CFR Part 20 and change surveillance requirements. The NRC staff has determined that the amendments involve 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 amendments involve no significant hazards considera-tion, and there has been no public comment on such finding (56 FR 24214).
Accordingly, the amendments meet 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 amendments.
5.0 CONCLUSION
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 Commission'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.
Principal Contributors: Robert Kirkwood (Generic Issue 70)
Edward Throm (Generic Issue 94)
Sheri Peterson, Project Manager Date: July 23,1993 I
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