ML20133D932
| ML20133D932 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/24/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20133D930 | List: |
| References | |
| TAC-59821, TAC-59822, NUDOCS 8508070521 | |
| Download: ML20133D932 (4) | |
Text
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UNITED STATES
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g NUCLEAR REGULATORY COMMISSION g
j WASHINGTON, D. C. 20555
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SAFETY EVALUATION MILLSTONE NUCLEAR POWER STATION, UNIT 3 RELATED TO AMENDMENT NO. 12 TO CONSTRUCTION PERMIT CPPR-113 INTRODUCTION By letter dated March 1, 1985, the Northeast Nuclear Company (the applicant) i on behalf of itself and sixteen owners
- requested an amendment to Construction Pennit CPPR-113 to incorporate the partial Exemption requested by the appli-i cant by letters dated September 12, 1984, October 18, 1984 and May 7, 1985 i
pertaining to General Design Criterion (GDC) 4 of 10 CFR 50, Appendix A.
The I
limited schedular exemption granted by the Commission 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 three primary loops in the Millstone 3 primary coolant system for a period ending at the completion of the second refueling outage, pending the outcome of rulemaking on this subject. The September 12, 1984 letter also included an analysis of the occupational radiation dose reduction which con-stituted a value-impact analysis associated with the exemption request. The l
value-impact analysis together with the technical information contained in Westinghouse Report WCAF-10587, provide a comprehensive justification in sup-port of requesting a partial exemption from the requirements of GDC 4.
EVALUATION r
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 June 5, 1985 letter. A summary of the staff's evaluation, findings and conclusions are immediately below.
- The following are the holders of Construction Permit No. CPPR-113: Central Maine Power Company, Central Vermont Public Service Corporation, Chicopee Municipal Lighting Plant, City of Burlington, Vennont, Connecticut Municipal Electric Energy Cooperative, The Connecticut Light and Power Company, Fitchburg Gas and 61ectric Light Company, Massachusetts Municipal Wholesale Electric Company, Montaup Electric Company, New England Power Company, Northeast Nuclear Energy Company, Public Service Company of New Hampshire, The Unite'd Illuminating Company, Vermont Electric Cooperative, Inc., The Village of Lyndoriville Electric Department, Western Massachusetts Electric Company, and Vermont Electric Generation and Transmission Cooperative, Inc.
8500070521 850724 PDR ADOCK 0 3
SUMMARY
OF EVALUATION FINDINGS From its evaluation of the analysis contained in Westinghouse Report WCAP-10587 for Millstone, Unit 3, the staff found that the applicant presented an accept-able technical justification which adequately addressed the staff's evaluation criteria, to eliminate the dynamic loading effects associated with the postulated full flow area circumferential and longitudinal pipe ruptures in the raain loop primary coolant system of Millstone 3.
These dynamic loading effects include pipe whip, jet impingement, asymmetric pressurization transients and break associated dynamic transients in unbroken portions of the main loop and con-nected branch lines (branch line LOCA loads will be retained in the design basis).
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This finding does not in any way affect the design bases for the containmenk, and compartments, the emergency core cooling system, equipment qualification, engineered safety features systems response, or the design of the Reactor Coolant System (RCS) heavy component supports.
This finding is predicated on the fact that each of the parameters evaluated for Millstone, Unit 3 is enveloped by the generic analysis perfonned by Westinghouse, contained in Westinghouse Report WCAP-9558, Revision 2, and accepted by the staff in Enclosure (1) to NRC Generic Letter 84-04 (February 1,1984). Specifically, the NRC determined that:
(1) The loads associated with the highest stressed location in the main loop primary system piping are 2032 kips (axial), 28,789 in-kips (bending moment) and result in maximum stresses of about 78% of the bounding stresses used by Westinghouse in Reference 3.
(2) For Westinghouse plants, there is no history of cracking failure in reactor primary coolant system loop piping. The Westinghouse reactor coolant system primary loop has an operating history which demonstrates its 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 (low and high cycle).
This o 400 reactor-years, including five (5)perating history totals over plants each having 15 years of operation and 15 other plants with over 10 years of operation.
(3) The leak rate calculations performed for Millstone 3, using an initial through-wall crack of 7.5 inches are identical to those of Enclosure 1 to Reference 2.
The Millstone plant has an RCS pressure boundary leak detection system which is consistent with the guidelines of Regulatory Guide 1.45, and it can detect leakage of one (1) gpm in one hour. The calculated leak rate through the postulated flaw results in a factor of at least 10 relative to the sensitivity of the Millstone 3 detection systems.
(4) The margin in terms of load of the Millstone unit based on fnacture mechanics analyses for the leakage-size crack under normal plus SSE loads is within the bounds calculated by the staff in Section 4.2.3 of Enclosure 1 to Reference 2.
Based on a limit-load analysis, the load margin is about 2.8 and based on the J limit discussed in (6) below, the margin is at least 1.5.
(5) The margin between the leakage-size crack and the critical-size crack was calculated by a limit load analysis. Again, the'results demonstrated that a margin of at least 3 exists and is within the bounds of Section 4.2.3 of Enclosure 1 to Reference 2.
(6) As an integral part of its review, the staff's evaluation of the
'l material properties data of Reference 7 is enclosed as Appendix I to this Safety Evaluation Report.
In Reference 7, data for ten (10) plants, including the Millstone unit, are presented, and lower bound or " worst case" materials properties were identified and used in the analysis performed in the Reference 1 report by Westinghouse. The 2
applied J for Millstone 3 in Reference 1 was less than 3000 in-lb/in and hence the staff's upper bound on the applied J (refer to Appendix I, page 6) was not exceeded.
ENVIRONMENTAL ASSESSMENT In advance of issuing the Exemption, the Commission published in the Federal Register on May 29, 1985 (50 FR 21954) an " environmental assessment and Tinding 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 considered in the Final Environmental Statement (construction permit) for Millstone, Unit 3.
The staff has determined that the amendment involves 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 determined that the amendment involves no significant hazards considerations.
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 this amendment.
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CONCLUSION In granting the limited schedular Exemption, the staff found that the advanced fracture mechanics techniques used by the applicants provided an assurance that flaws in primary system piping will be detected before they reach a size 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. Addi-tionally, consideration of such dynamic effects associated with previously postulated pipe breaks is unnecessary.
With full protection against dynamic effects provided by advanced analysis techniques, and based on the consider-ations discussed above, we conclude that: (1) the proposed amendment to Construction Permit CPPR-113 permitting the use of the Exemption in construc-tion of Millstone, Unit 3 does not involve a significant increase in the probability or consequences of accidents previously considered, does not create the possibility of an accident of a type different from any evaluated previously, does not involve a significant decrease in a safety margin, and thus does not involve a significant hazards consideration; (2) there is reasonable assurance that the health and safety of the endangered by operation in the proposed manner; and (3)public will not be such activities will be in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security, or to the health and safety of the public.
Date of Issuance: JUL 2 41985
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