ML20137M725

Safety Evaluation Supporting Amends 92 & 82 to Licenses DPR-39 & DPR-48,respectively

ML20137M725
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	01/16/1986
From:	NRC COMMISSION (OCM)
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Shared Package
ML20137L889	List: ML20137L885 ML20137L920 ML20137M725
References
NUDOCS 8601280350
Download: ML20137M725 (4)

Text

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SAFETY EVALUATION 8Y THE OFFICE OF NUCLEAR REACTOR REGULATION .

RELATED TO AMENDMENT NO.92 TO FACILITY OPERATING LICENSE N0. OPR-39 AND AMENDMENT NO. 82 TO FACILITY OPERATING LICENSE NO. OPR-48 COMONWEALTH EDISON COMPANY ZION NUCLEAR POWER STATION, UNITS 1 AND 2 00CKET N05. 50-295 AND 50-304 INTRODUCTION In a letter from P. C. Le Blond to H. R. Denton dated August 19, 1985, the Comonwealth Edison Company (the licensee) proposed amendments to Facility Operating Licenses No. DPR-39 and DPR-48, Appendix A. Section 4.3.4.0-Materials Irradiation Surveillance Specimen Inspection. These changes proposed a revised withdrawal schedule fpr reactor vessel surveillance capsules in Zion Nuclear Power Station Units No. I and 2. In support of these amendments the licensee provided Westinghouse Report WCAP-IO902, " Plant Specific Neutron Fluence Evaluation for Zion Units 1 and 2."

The capsule withdrawal schedules contained in Section 4.3.4.D of the Zion Technical Specification required the licensee-to remove four capsules. Those withdrawal schedules were based on previous fuel loading designs and require-ments of 10 CFR 50, Appendix H which were in effect on the date those schedules were approved. As a result of changes to low leakage fuel design at Zion and the capsule withdrawal requirements in 10 CFR 50, Appendix H, the licensee has proposed changes to the capsule withdrawal schedules to reflect the new lower rate of accumulation of neutron radiation. Our discussion, which follows, describes the requirements in 10 CFR 50, Appendix H for withdrawal of the surveillance capsules and the licensees proposed ..P.F '

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DISCUSSION A reactor vessel surveillance program must meet the requirements of Appendix H, 10 CFR 50, which was published in the Federal Register on May 21, 1983 and became effective on July 26, 1983. This appendix indicates that the purpose of the material surveillance program is to monitor changes in the fracture toughness properties of ferritic materials in the reactor vessel beltline. This appendix-indicates that the schedule for surveillance capsules withdrawn af ter July 26, 1983 must meet, to the extent practical, with the requirements of ASTM E 185-82. For Zion Units 1 and 2 this specification recomends that five capsules be withdrawn from the reactor vessel. The fourth capsule is to be withdrawn when the neutron fluence for the capsule is approximately end-of-life (E0L) fluence at the reactor vessel inner wall location or 15 effective full power years (EFPY), whichever comes first. The fifth capsule is to be withdrawn when neutron fluence for the capsule is not less than once or greater than twice the peak EOL fluence or at EOL of the reactor vessel.

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Each reactor vessel at Zion contained eight capsules at the time the plants went into commercial operation. Three capsules have been removed from Zion Unit I and tested. Two capsules have been removed from Zion Unit 2 and tested.

The licensee proposes to remove and test one additional capsule (Capsule Y) from each reactor vessel and change the status of Capsule Y to " standby" status. The I

l licensee desires to leave Capsule Y in the vessel to accumulate more neutron I radiation. The staff agrees that Capsule Y should be held in the vessel to l

l accumulate more neutron radiation. The licensee proposed to remove Capsule Y from each reactor vessel when the neutron fluence received by the capsule is predicted to reach the approximate E0L fluence at the reactor vessel inner wall. These fluence predictions are based on the fluence evaluation in Westinghouse Report WCAP-10902. The fluence predictions are based upon transport calculations using DOT discrete ordinate transport code and the sailor cross-section library.

Two sets of transport calculations were perfonned, which utilized design basis and .clant specific core power Gtributions, respectively. This transport methodology has been benchmarked in the Oak Ridge National Laboratory PCA facility and to Westinghouse power reactor surveillance data. The Westinghouse

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,. 3-report indicates that the benchmarking studies show that the fluence predictions are within 215% of measured values at the surveillance capsule. This small amount of uncertainty demonstrates the accuracy of the transport. calculation.

Future confirmation of this accuracy will be obtained from the scheduled withdrawal of each capsule from each unit and the Zion excore dosimetry program.

SUMMARY

Based on the neutron fluence calculations documented in Westinghouse Report WCAP 10902, Capsule Y should provide fracture toughness data at neutron fluence representing E0L conditions in the reactor vessel and Capsule Y should remain in the vessel to accumulate more neutron radiation. Based on this conclusion, the proposed amendments should be incorporated into the Facility Operating Ltcense s No. DPR-39 and DPR-48. However, to be in conformance with ASTM E 185-82, the licensee mpst provide a revised schedule for withdrawal of one additional capsule from each rector vessel when the neutron fluence at the capsule is not less than once or greater than twice the peak EOL neutron fluence at the inner wall of the reactor vessel. This additional capsule will nere effectively monitor changes in the fracture toughness properties of ferritic tnaterials in the reactor vessel beltline than the current schedule and will meet the withdrawal schedule requirements of ASTM E 185-82. This revised schedule should be provided within one year of receipt of this evaluation. The request for this revised schedule does not affect our conclusions about the immediate acceptability of the proposed amendments.

ENVIRONMENTAL CONSIDERATION These amendments involve a change in the installation or use of the facilities components located within the restricted areas as defined in 10 CFR 20. The staff has detennined that these amendments involve no e' ' U'->nt

• reece in the amounts, and no significant change in the types, or any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation l

exposure. The Commission has previously issued a proposed finding that these amendments involve no significant hazards consideration and there has been no public coment on such finding. Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR Sec 51.22(c)(9). Pursuant to 10 CFR Sl.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.

CONCLUSION We have 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, and (2) such activities will be conducted in compliance with the Comission's regulations and the issuance of these amendments will not be inimical to the connon defense and security or to the health and safety of the public.

Dated: January 16, 1986 PRINCIPAL CONTRIBUTOR:

B. Elliot I

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