ML20086C007
| ML20086C007 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/18/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20086C005 | List: |
| References | |
| NUDOCS 9111210309 | |
| Download: ML20086C007 (5) | |
Text
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SAFETY EVAL.UATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REL ATED TO AMENDMENT NO.165 TO FACILITY OPERATING LICENSE NO. DPR-53 AND AMENDMENT NO.145 TO FACILITf OPERATING LICENSE NO. DPR-69 BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-317 AND 50-318
1.0 INTRODUCTION
By letter dated August 27, 1991, the Laitimore Gas and Electric Company (the licensee) submitted a request for changes to the Calvert Cliffs Nuclear Power Plant, Unit Nos. I and 2, Technical Specifications (TS). The reouested changes would revise the TS to increase the specified snubber functional +.esting and service life monitoring surveillance intervals from 18-months to 24-morths to accormodate the 24-month fuel cyclet currently in use at Calvert Cliff s.
This requested change is based on a history of low snubber failure rates and an effective snubber maintenance program.
As requested in Generic Letter (GL) 91-04, dated April 2,1991, " Changes In Technical Specification Surveillance Intervals To Accornmodate a 24-month fuel Cycle," the licensee provided an evaluation in w pport of the change which concludes that the effect on safety is small and does not invalidate any assumption in the plant licensing basis.
Additionally, the licensee requested that the Bases be updated, including TS Basis 4.0.2, to reflect the guidance provided in the recently issued GL 91-04 and support the requested changes.
2.0 EVALUATION Subsequent to increasing the refueling interval from 18-months to 24-months, the licensee requested amendments to the TS of both units which added the definition
- Refueling Intervb1 - at least once per 24-months" to Table 1.2 of TS Definition 1.22, " Frequency Notation." The definition for "R - at least once per 18-months" remains. This is necessary to assure the safety-related systems and components which have not yet been approved for 24-month surveillance intervals, have their surveillances performed at the required 18-months intervals. This is accomplished during scheduled mid-cycle surveillance / maintenance outages until all the safety-related systems and components have been approved for the 24-month refueling interval. The Commission issued Amendment No.133 to Facility Oper::tir.g License No. DPR-53 and Amendment No.114 to Facility Operating License No. DPR-69 for Units Nos. I and 2, respectively, by letter dated December 21, 1988, which included the definition for a 24-month Refueling Interval.
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l The changes were consistent with the current guidance in GL 91-04 and, therofore, no other changes are necessary in relation to defining the existing suneillan;e intervals in the TS to support the requested changes to the snutber furictional testing and service life monitoring surveillance intervals.
Safety-related hydraulic snubbers are provided as movement restraints on plant safety systems to provide protection of structural integrity during and following an event involving dynamic loading, yet allows for thermal movement during normal system temperature fluctuations and transients.
The amendment request is to extend the functional testing and service life monitoring surveillance frequencies from 18-month intervals to 24-month intervals.
Specifically, the requested changes are: a) TS Surveillance Requirement 4.7.8.lc would be changed from once per 18-months to require functional testing once per refueling interval and the term "during shutdown" would be deleted to avoid any confusion with defined conditions or requirements during Hot Shutdown or Cold Shutdown, b) TS 4.7.8.1.e would also be changed from once per 18-months to require service life monitoring once per refueling interval; ind, c) the TS Bases are modified to reflect the requested changes, including the Basis for TS 4.0.2, to reflect the proposed wo ding of 61. 91-04.
As noted in the licensee's amendment request, Calvert Cliffs Unit I contains 108 accessible snubbers and 218 snubbers which are inaccessible during puwer operation.
Unit 2 similarly contains 109 accessible snubbers and 172 inaccessible snubbers.
The licensee's review of the historical failure rate data for the hydraulic snubbers installed at the Calvert Cliffs facility has indicated that the snubbers are very reliable. The visual inspections of 6,681 snubber at the f acility have only identified 19 failures which is a failure rate of less than 0.28%. Only seven of 614 snubbers which have been functionally tested were considered failures which is a failure rate of about 1.14%.
The licensee has also compared the failure rate at the Calvert Cliffs facility with that of industry. The overall failure rate reported since 1975, based on 35,850 visual hydraulic snubber inspections,-is 870 failed or degraded which is less than 2.5%.
The results of 10,000 hydraulic snubber functional tests were approximately 1200 failures which is a failure rate of about 12.1%.
The staff has determined that the increase in the surveillance interval from 18-months to 24-months for the functional testing specified in TS 4.7.8.1.c of the hydraulic snubbers is acceptable. This determination is based on the lif storical data detailed above which indicates the overall reliability of the snubbers at the Calvert Cliffs facility is essentially one order of magnitude above the industry average, provides reasonable assurance that the iritial assumptions in_the plant licensing basis remains valid, and the overall impact on safety is determined to be small. We further have determined that the deletion of the term "during shutdown" is acceptable in that the term
" refueling interval" has already been defined in the existing TS and the requested deletion results in a clearer and more precise TS requirercent.
. The licensee's service life monitoring program provides for a periodic snubber performance evaluation to determine which snubbers would reach the end of their expected service life prior to the next review. These snubbers are replaced or refurbished to extend their service life.
Extending the monitoring program intervals from 18 to 24 months would essentially be on administrative change to include the new interval length into the program.
The requested change assures that the first of the 24-month evaluations will be performed within 18-months of the last evaluation.
The staff has determined that the increase in the service life monitoring program specified in TS 4.7.8.1.e from 18-months to 24-months is acceptable.
This conclusion is based on the overall reliability of the installed snubbers, as previously discussed, and that the first 24-month evaluation will be performed within 18-months of the latest evaluation to provide assurance of a continuous monitoring program.
Thus, the overall impact on safety resulting from this requested change is determined to be small and provides reasonable assurance that the initial assumptions in the plants licensing bases remains valid.
The requested changes tn TS Bases 3/4.7.8 reflect the change from the 18-month surveillance interval to a 24-month interval and specify the surveillances be performed during the previously defined " Refueling Interval," The requested changes to TS Bases 4.0.2 reflect the recomended wording in GL 91-04 We have determined that the requested TS Bases changes are consistent with the recomendations of GL 91-04, reflect the intent of the guidance provided in the GL, and support the requested TS surveillance interval changes and are, therefore, acceptable.
3.0 STATE. CONSULTATION In accordance with the Comission's regulations, the Maryland State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility' component located within the restricted area as defined in 10 CFR Part 20.and changes to the 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 affluents that may be released offsite and that thera is no significant increase in individual or cumulative occupatIonalradiationexposure. The Comission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comeat on such finding (56 FR 47229). Accordingly the amendments meet the eligibility criteria for categorical exclusionsetforthIn10CTR51.22(c)(9).
Pursuantto10CFR51.22(b)no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
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5.0 CONCLUSION
The Connission 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
T. Dunning D. Mcdonald Date: Novernber 18, 1991 4
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November 18, 1991 A copy of the related Safety Evaluation is enclosed.
A Notice of issuance will be included in the Comission's next regular biweekly Federal Register no* ice.
Sincerely.
Original Signed By:
Daniel G. Mcdonald, Senior Project Manager Preiect Directorate I.1 Division of Reactor Projects I/II Office of Nuclear Reactor Regulation
Enclosures:
1.
Amendmeet No.165 to DPR.53 2.
Amendwnt No.145 to 0^R-69 3.
Safety Evaluation cc w/ enclosures:
See next page
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OFFICIAL RECURD CUFY Document Name:
CC1/2 AMDT TAC NOS. 81358/9
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