ML20136E268
| ML20136E268 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/06/1985 |
| From: | Knighton G Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20136E246 | List: |
| References | |
| NUDOCS 8601060481 | |
| Download: ML20136E268 (4) | |
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UNITED STATES E
NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D. C. 20555 r
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SAFETY EVALUATION PALO VERDE NUCLEAR GENERATING STATION, UNITS 2 AND 3 RELATED TO AMENDMENT TO CONSTRUCTION PERMIT NOS. CPPR-142 AND CPPR-143 Introduction By letters dated December 10, 1984 and July 16, 1985, the Arizona Public Service Company on behalf of itself and the Salt River Proje.ct Aaricultural Improvement and Power District, the Southern California Edison Company, the El Paso Electric Company, the Public Service Company of New Mexico, the Los Angeles Department of Water and Power
- and the Southern California Public i
Power Authority (the applicants) submitted an application for amendments to Construction Pemit Nos. CPPR-142 and CPPR-143 for Palo Verde Units 2 and 3.
The application requested a schedular partial exemption from General Design l
Criterion (GDC) 4 of 10 CFR 50, Appendix A.
The limited schedular exemption granted by the Comission permits the applicants to eliminate the installation of protective devices and the consideration of the dynamic effects and loading conditions associated with postulated pipe breaks in the primary loops in the j
Palo Verde Units 2 and 3 primary coolant systems for a period ending with the i
second refueling outage of each unit, pending the outcome of rule makina on 1
i this subject. In support of the application, the applicants reference two documents: a report submitted by CE by letter dated June 14, 1983 (Reference 1) and an amendment to the CE report submitted by letter dated December 23, 1983 (Reference 2).
i Evaluation The staff's detailed evaluation and basis for granting the partial exemption to the requirements of GDC 4 are delineated in the Exemption enclosed with the staff's (exemp. date) letter. A summary of the staff's evaluation, findings and conclusions are immediately below.
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Sumary of Evaluation Findinos l
The staff's evaluation of the CE submittals (References 1 and 2) concluded l
that there are adequate technical bases to justify that, for CESSAR plants.
- The Los Angeles Department of Water and Power will not actually become a co-owner until after Palo Verde Unit 1 is placed into comercial operation, j
8601060481 851206 DR ADOCK 05000529 PDR l
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w 2-guillotine type failures of the RCS main loop piping need not be considered in the design basis and hence, pipe whip restraints and jet impincement shields for the RCS piping are not required. The submittals were made to support reouests, by applicants with the CESSAR plant, for an exemption to GDC 4'as it relates to pipe whip restraints and jet impinoement shields on the RCS primary piping. No other changes in design requirements are addressed within the scope of the referenced reports; e.g., no changes to the definition of a LOCA nor its relationship to the regulations addressing design requirements of ECCS (10 CFR 50.46), containment (GDC 16, 50), other engineered safety features and the conditions for environmental qualification of equipment (10 CFR 50.49). The applicants' amendment request also states that no other
- changes in design requirements are being requested. Specifically, the NRC detemined that:
(1) The loads associated with the highest stressed locations in the main loop primary system piping were provided and,are within Code allowables.
(2) For CE plants, there is no history of cracking failure in reactor primary coolant system loop piping.
CE reactor coolant system primary loops have an operating history which demonstrates their inherent stability. This includes a low susceptibility to cracking failure from the effects of corrosion (e.g., intergranular stress corrosion cracking), water hammer, or fatigue (Iow and high cycle).
This operating history includes several plants with many years of operation.
(3) The results of the leak rate calculations perforr_d for CESSAR, used initial postulated throughwall flaws that are equvalent in size to that in Enclosure 1 to NRC Generic Letter 84-04 (Reference 3).
CESSAR facilities are expected to have an RCS pressure boundary leak detection system which is consistent with the guidelines of Regulatory Guide 1.45 so that they can detect leakage of one (1) gpm in one hour.
The calculated leak rate through the postulated flaw is large relative to the staff's required sensitivity of plant leak detection systems.
The margin is at least a factor of ten (10) on leakage.
(4) The expected margin in terms of load for the leakage-size crack under normal plus SSE loads is greater than a factor e three (3) when compared to the limit load.
In addition, the st
- found i
a significant margin in terms of loads larger than normal plus SSE loads.
(5) The margin between the leakage-size crack and the critical-size crack was calculated. Again, the results demonstrated that a crack size margin of et least a~ factor of three (3) exists.
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Environmental Assessment In advance to issuing the Exemption, the Comission published in the Federal Register on November 29, 1985 (50 FR 48509) an " environmental assessment and L
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finding of no significant impact." It'was stated in that assessment that the planned Exemption action would not have a significant effect on the quality of the human environment. The Exemption granted involves design features located entirely within the plant restricted area as defined in 10 CFR Part 20; does not affect plant radioactive and non-radioactive effluents; has no other environmental impact; and does not involve the use of resources not previously i
considered in the Final Environmental Statement (construction permit) for Palo Verde Units 2.and 3.
The staff has detennined that the amendments involve no significant increase int 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 Comission has determined that the amendments involve no significant hazards considerations.
Accordingly, the amendments meet the eligibility critoria for categorical i
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 I
in connection with the issuance of the amendments.
Conclusion In granting the schedular partial Exemption, the staff found that the advanced fracture mechanics techniques used by the applicants provided an assurance t
that flaws in. primary system piping will be detected before they reach a size I
that could lead to unstable crack growth.
For this reason, further protection provided by protective devices against the dynamic effects resulting from the discharge from postulated breaks in the primary piping is unnecessary.
Additionally, consideration of such dynamic effects associated with previously postulated pipe breaks is unnecessary. With full protection against dynamic t
effects provided by advance analysis techniques, and based on the considerations discussed above, we conclude that:
(1) the proposed amendnent to Construction Permit Nos. CPPR-142 and CPPR-143 permitting the use of the Exemption in construction of Palo Verde Units 2 and 3 do not involve a significant increase in the probability or consequences of accidents previously considered, 00 not create the possibility of an accident of a type different from any evaluated previously, do not involve a significant decrease in a safety l
margin, and thus do not involve a significant hazards consideration; (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner; and (3) such activities will be in compliance with the Connission's reculations, and the issuance of the amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Date of issuance: December 6, 1985 l
LIST OF REFERENCES (1) Letter A. E. Scherer of Combustion Engineering, Inc., to Darrell G.
Eisenhut.. Docket No. STN 50-470, June 14, 1983, with enclosure,
" Basis for Design of Plant Without Pipe Whip Restraints for RCS Main Loop Piping".
(2) letter A. E. Scherer of Combustion Engineering, Inc., to Darrell G.
Eisenhut, Docket No. STN 50-470F, December 23, 1983, with enclosure,
" Leak Before Evaluation of the Main Loop Piping of a CE Reactor Coolant System," Revision 1, November 1983.
(3) NRC Generic Letter 84-04, " Safety Evaluation of Westinghouse Topical Reports Dealing with Elimination of Postulated Breaks in PWR Primary Main Loops," February 1, 1984 1
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