ML20207S563

Safety Evaluation Supporting Amends 101 & 91 to Licenses DPR-39 & DPR-48,respectively

ML20207S563
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	03/13/1987
From:	Office of Nuclear Reactor Regulation
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ML20207S557	List: ML20207S556 ML20207S561 ML20207S563
References
NUDOCS 8703200038
Download: ML20207S563 (4)

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. y, NUCLEAR REGULATORY COMMISSION wasHWGTON, D. C. MS5 '

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.101 TO FACILITY OPERATING LICENSE NO. DPR-39 AND AMENDMENT NO. 91 TO FACILITY OPERATING LICENSE NO. DPR-48 COMMONWEALTH EDISON COMPANY ZION NUCLEAR POWER STATION, UNITS 1 AND 2 i DOCKET NOS. 50-295 AND 50-304 i

INTRODUCTION In a letter from P. C. Le91ond to H. R. Denton, dated December 5, 1986, the Comonwealth Edison Company (the licensee) submitted a proposed amendment to Facility Operating License Nos. DPR-39 and DPR-48, Appendix A. Sections 3.3.2 j and 4.3.2 on Pressurization and System Integrity. The proposed amendment j

provides a revised set of reactor vessel heatup and cooldown pressure-temperature limit curves for the Zion Nuclear Power Station Units 1 and (EFPY1 2 for a period of time correspondino to 15 effective full power years The calculational procedure was discussed in Reference I which was submitted as Attachment 3 to the December 5,1986 letter. *

DISCUSSION

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Pressure-temperature limits must be calculated in accordance with the reoutrements of Appendix G 10 CFR 50, which became effective on July 26, 1983. Pressure-temperature limits that are calculated in accordance with the mouirements of Appendix G 10 CrR 50, are dependent upon the initial reference temperature (R 1 for the limiting materials in the beltline and I

closure flange regions o Ne reactor vessel and the increase in P.T resulting from neutron irradiation damage to the limiting beltline NIerial.

i In addition the Charpy upper-shelf energy must meet the reouirements of Section IV.A.1 of Appendix G,10 CFR 50 Section IV.A.1 requires, in part, i

i that the Charpy upper-shelf energy throughout the life of the vessel be no less than 50 ft-lb, unless it is demonstrated in a manner approved by the Director, Office of Nuclear Reactor Regulation, that lower values of upper-shelf energy will provide margins of safety against fracture equivalent to those required by Appendix G of the ASME Code. The licensee indicated that the initial RT beltline resto$T offor the limiting materials in the closure flange and the Zion Units 1 and ? vessel was estimated using the method recomended by the staff in Rranch Technical Position MTER 5-2,

" Fracture Toughness Requirements", which is documented in the Standard Review Plan, Section 5.3.2, " Pressure-Temperature Limits". )

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The limiting beltline material for Zion Units 1 and ? is the weld metal WF70 (weld wire heat no. 72105 and Linde 80 flux lot no. 8669). This limiting weld metal is in the Zion Unit 1 intermediate to lower shell otrth weld seam and the Zion Unit 2 lower shell longitudinal weld seams.

that Branch Technical Position MTEB 5-2 results in an initial RTThelicenseeindicgtes of 0 F for l

the limiting weld metal. Thelicenseeindicatesthatthelimiti$Tclosure '

flangeregionmaterialforZionUnits1and2isthefionUnitIclosurehead flange, in which the initial RT

{ NDT is estimated as 55 F.

i The increase in RT resulting from neutron irradiation damage depends upon thepredictedaroukTof neutron fluence and the rate of embrittlement of the limiting reactor vessel beltline material. The licensee estimated that the '

i neutron fluence beltline weld locationat the will inside besurface 0.93 x 10gof ghe 71gn Units 1 and ? vessel at the -

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~ n/cm at 15 EFPY. Detailed discussion of the fluence evaluation was provided in Reference 2.

l The increase in RT resulting from neutron irradiation damage was estimated L by the licensee us k the empirical relationship documented in Proposed Revision 2 to Regulatory Guide 1.99 " Radiation Damage to Reactor Vessel Materials", which was issued for public comment during February 1986, and was reviewed by NRR, CRGR, and ACRS. The proposed revision has two methods for calculating the increase in RT .

One method is to be used when test data '

j from surveillance material is Miiabie and the other when test data from surveillance material is unavailable.

, , The proposed regulatory guide permits the use of surveillance material to determine the increase in RT when the five criteria-in the discussion

! section of the guide have beksatisfied. Surveillance data are available for the Zion Units 1 and 2 limiting weld metal. Rased on the infomation in i

References 3 and 4, the Zion Units 1 and 2 surveillance material appears to satisfy these criteria. Since the initial RT of the limiting weld metal is 4

not measured but is a generic mean value, theN hpropriate procedures in

! Revision 2 to Regulatory Guide 1.99 were used. The Zion Units 1 and 2 heatup l and cooldown pressure-temperature limit curves are based on the increase in RT l

! subi11ancematerialisavailable. calculated by thedata Surveillance method from recomended Capsules T, U,byand the proposed g!

I i X for Zion Unit I and Capsules U and T for Zion Unit 2 are considered in l l

Reference 1. Although Zion Unit I and Zion Unit 2 capsules contained the same i limiting weld metal, the surveillance, data from Zion Unit I capsules produced

' a slightly larger chemistry factor (CF1 resulting in a slightly larger  !

estimated increase in RT Thus, the weld metal in Zion Unit 1 is the limitingmaterialanditNu.rveillan Zion Units 1 and 2 pressure-temperatu(e re limitdata curves, were used in the calculation of the i i f In Reference 5, the licensee indicated that the Charpy upper-shelf energy of i

the limigng be{tline material will decrease to 50 ft-lb at a fluence of 0.5 x 10 n/cm . The licensee estimated that this fluence level will he

reached after approximately 14 EFPY in 1994 We have confimed the licensee's i estimates using the Zion Units I and 2 surveillance data. Since the )

surveillance data indicate that the Charpy upper-shelf energy of the limiting

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weld metal will meet the requirements of Appendix G,10 CFR 50 for 14 EFPY, the pressure-temperature limit curves will only satisfy the requirements of Appendix G, 10 CFR 50 for 14 EFPY, We have used the unirradiated RT for beltline and closure flange materials, whichwerepreviouslydiscussed,gEkeneutronfluenceestimatesofthelicensee, the proposed Regulatory Guide 1.99 Rev. 2 method of estimating neutron irradiation i damage Standard Review Plan 5.3.2 method calculating pressure-temperature limits, and the surveillance capsule data to evaluate the licensee's proposed pressure-temperature limits. Our evaluation indicates that the proposed pressure-temperature limits meet the safety margins of Appendix G.10 CFR 50, for a period of time corresponding to only 14 EFPY. The licensee must demonstrate compliance with Section V.C of Appendix G,10 CFR 50 that the pressure-temperature limit curves will meet the safety margins of Appendix G,10 CFR 50 when the Charpy upper-shelf energy for the limiting reactor vessel material is below 50 ft-lb. Furthermore, pursuant to Section V.E. of Appendix G,10 CFR 50, the licensee has to submit a proposed program for staff review at least 3 years prior to the EFPY date.

As the result of a telephone conference with the staff, the licensee, by letter of February 27, 1987, amended its original submittal requesting that the revised heatup and cooldown curves be applicable to 14 EFPY, which corresponds to the supporting information in Reference 6, instead of 15 EFPY oricinally requested.

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

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staff has determined that these 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 these amendments involve no significant hazards consideration and there has been no public comment on such findino. Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10.CFR Sec 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 these amendments.

j 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 Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.

Dated: March 13, 1987 PRINCIPAL CONTRIBUTOR:

Sam Lee

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REFERENCES (1) Westinghouse Report WCAP-11?47, "Heatup and Cooldown Limit Curves for the Commonwealth Edison Company Zion Units 1 and 2 Reactor Vessel" H. Gong, August 1986.

(2) Westinghouse Report WCAP-10902, " Plant Specific Neutron Fluence Evaluation for Zion Units 1 and 2", S. L. Anderson, August 1085.

(3) Southwest Research Institute Final Report, SwRI Project No. 06-7484-001,

" Reactor Vessel Material Surveillance Program for Zion Unit No.1 Analysis of Capsule X", E. B. Norris, March 1984 (4) Southwest Research Institute Final Report, SwRI Project No. 06-6901-001,

" Reactor Vessel Material Surveillance Program for Zion Unit No. 2 Analysis of Capsule T", E. B. Norris, July 6,1983.

(5) Letter from P. C. LeBlond (Commonwealth Edison) to H. R. Denton (NRC) dated December 20, 1985.

(6) Letter from P. C.

dated February 27,LeBlond 1987. (Commonwealth Edison) to H. R. Denton (NRC)

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