ML20214L931

Corrected Safety Evaluation Re Projected Values of Matl Properties for Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events.Licensee Projections Acceptable

ML20214L931
Person / Time
Site:	Point Beach
Issue date:	09/04/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20214L914	List: ML20214L912 ML20214L931
References
REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR TAC-59972, TAC-59973, NUDOCS 8609100459
Download: ML20214L931 (5)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING PROJECTED VALUES OF MATERIAL PROPERTIES FOR FRACTURE TOUGHNESS REQUIREMENTS FOR PROTECTION AGAINST PRESSURIZED THERMAL SHOCK EVENTS WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCLEAR PLANT UNIT NOS. 1 AND 2 DOCKET NOS. 50-266 and 50-301 INTRODUCTION As required by 10 CFR 50.61, " Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock" (PTS Rule) which was published in the Federal Register July 23, 1985, the licensee for each operating pressurized water reactor "shall submit projected values of RTPTS (at the inner vessel surface) of reactor vessel beltline materials by giving values from the time of submittal to the expiration date of the operating license. The assessment must specify the bases for the projection including the assumptions regarding core loading patterns. This assessment must be submitted by January 23, 1986, and must be updated whenever changes in core loadings, surveillance measurements or other information indicate a significant change in projected values."

By letters dated January 20, and March 14, 1986 Wisconsin Electric Power Company (the licensee) submitted projected values of RT PTS t gether with material properties and fast neutron fluence of reactor vessel beltline materials for the Point Beach Nuclear Plant, Unit Nos. I and 2. The RT fluence values were projected to July 19, 2007 and July 25, 2008 forUnN!and I and 2 respectively JN expiration dates of the current licenses), as well as for the design vru el life of 32 effective full power years.

By letter da m Ju . 8, 1985, the licensee has applied for license amendments-which would extend the operating licenses to October 5, 2010 for Unit 1 and March 8, 2013 for Unit 2. The licensee's January 20 and March 14 1986 submittals also provided values of RT together with material properties and fast neutron fluenceofreactorvessel$5tlinematerialsforUnits1and2projectedtothe requested extension dates.

EVALUATION OF THE MATERIALS ASPECTS The controlling beltline material from the standpoint of PTS susceptibility was identified to be the lower shell axial weld (SA-847), Weld Wire Heat No.

61782 for Unit I and the circumferential weld joining the intermediate to lower shell (Weld SA-1484), Weld Wire Heat No. 72442 for Unit 2.

The material properties of the controlling materials and the associated margins and chemistry factors were reported to be:

8609100459 860904-PDR ADOCK 05000206 P @c-

Unit 1 .

Utility Submittal Staff Evaluation Cu (copper content, %)- = 0.25 0.25 Ni (nickel content, %) = 0.55 0.55 I (Initial RT NDT, F) = 0 0 M (Margin, *F) = --

59 CF (Chemistry Factor, *F)= --

155.6-Unit 2 Utility Submittal Staff Evaluation Cu (copper content, %) = 0.26 0.26 Ni (nickel content, %) = 0.60 0.60 I (Initial RT NDT, ) = 0.0 0.0 M (Margin, *F) = 59 CF (Chemistry Factor, F)= 167 The controlling materials have been properly identified. The justification

given for the copper and nickel contents and the initial RTNDT *#"

acceptable. The margins have been derived from consideration of the bases for these values, following the PTS Rule, Section 50.61 of 10 CFR Part 50.

Therefore, Equation 1 of PTS rule governs and the chemistry factors are as shown above.

EVALUATION OF THE CALCULATED RT p73 The following evaluation concerns the estimation of the fluence to the pressure vessels for 32 effective full power years of operation and the expiration dates of the current licenses and the corresponding values of RT e f uences were PTS.

estimated using a benchmarked discrete ordinates code with a P3 "C" *#I"8 "P" proximation. The cross sections (the Westinghouse SAILOR library) are based on ENDF/B-IV. The neutron sources were derived from plant specific data and the future projections were conservative. Comparisons of calculational results with measurements of three surveillance capsules indicate that the calculations are conservative. We find that the esimations of the projected fluences are acceptable.

The critical element (for Unit 1) is the axial weld SA-847 (at a 15*

azimuthal angle) for which the projected fluence to 32 effective full power a

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2 years (EFPY) is 2.2x10 19 n/cgg. Thg projected fluence to the' current license expiration date is.l.90 x 10 n/cm . The equation specified in 10 CFR 50.61 applicable in this case is:

0 RT PTS

= I+M+(-10+470xcu+350xCuxNi) xf .27 where: I = initial RT ET

= 0*F M = uncertainty = 59 F Cu= w/o' Copper in weld SA-847 = 0.25 Ni= w/o Nickel in weld SA-847 = 0.55 f=peakfluenceE2,}90 MgV on' weld SA-847, multiplied by 10 cm /n = 2.2 for 32 EFPY and 1.0 for the current license expiration date 0

then: RT PTS

= 0+59+(-10+470x0.25+350x0.25x0.55)x2.2 27 RT = 59+155.6x1.2372 = 59+192.5 = 251.5*F $ 270*F for 32 EFN which is lower than 270*F, the applicable 10 CFR 50.61 criterion, thus, it is acceptable.

For the current license expiration, 0.27 then: RT PTS

= 0+59+ (-10+470x0.25+350x0.25x0.55) x RTp .73 = 59+155.6x1.1892 = 59+185.0 = 244.0 F $ 270 F which is lower than 270*F, the applicable 10 CFR 50.61 criterion, thus, it is acceptable.

ThecriticalelementforUnit2isthecircumferentialweldSA-1484forwhjch the projected fluence to 32 effective full power years is 3.45 x 10 n/cm .

19 The ojected fluence to the current license expiration date is 3.12 x 10 n/cm The equation specified in 10 CFR 50.61 applicable to the Point Beach 2 reactor pressure vessel is:

RT PTS

= I+M+(-10+470xCu+350xCuxNi)xf

• where: I = initial RT = 0*F ET M = uncertainty = 59 F Cu = w/o Copper in weld SA-1484 = 0.26

,u-Ni = w/o Nickel in weld SA-1484 = 0.60 f = peak fluence, E2 1.0 MeV on weld SA-1484, multiplied by 10'I9 cm 2/n = 3.45 for 32 EFPY and 3.12 for the current. license expiration date.

0 then: RT = 0+59+(-10+470x0.26+350x0.26x0.60)3.45 27 PTS RT = 59+166.8x1.397 = 292.0 F 5 300 F for 32 EFN3 The estimated value is lower than the applicable 10 CFR 50.61 criterion of 300'F and, therefore, it is acceptable.

For the current license expiration; 0

then: RT = 0+59+(-10+470x0.26+350x0.26x0.60)3.12 27 PTS RT PTS

= 59+166.8x1.360 = 285.8 F 5 300 F which is lower than the applicable 10 CFR 50.61 criterion of 300 F and, therefore, is acceptable.

EVALUATION OF THE FLUENCE ASPECTS In order to get an estimate of the available margin in terms of fluence, we use the same equation and solve for f when RT PTS

= 270 F and 300 F for Units 1 and 2, repsecti/ely; i.e.

For Unit 1:

270 = 59 + 155.6 x f.27 f.27 = 211 = 1.356 155.6 f = 3.09 and 3.09 = 1.626 1.9 This corresponds to about 15 calendar years of operation beyond the expiration of the current license.

For Unit 2:

300 = 59 + 166.8 x f.27 or f.27 = 241 = 1.445 or f = 3.91, and 166.8 3.91/3.12 = 1.253

~, .

This corresponds to about 10.1 calendar years beyond the expiration of the l current license.

CONCLUSIONS The licensee has calculated a RT of 244.0 F for Unit I and 285.8 F for Unit 2forthelimitingaxialwef3Smaterial (Unit 1) and circumferential weld material-(Unit 2) at the expiration dates of the licenses. This is less than 270*F or 300 F which are the screening criteria fcr the limiting materials at the expiration dates of the licenses. This is acceptable and thus meets the requirements of the PTS Rule.

Further, the calculations show that for both Units 1 and 2, available margin

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exists for operation beyond the expiration of the current license and beyond the requested license extension periods for both units (approximately 3 years for Unit I and 5 years for Unit 2). Therefore, the staff finds this to be acceptable for meeting the requirements of the PTS rule with respect to the requested license extensions.

In order for us to confirm the licensee's projected estimated RT p throughoutthelifeofthelicense,wewillrequestthelicensee[go submit a re-evaluation of the RT and comparison to the predicted value with future Pressure-Temperaturesubm!ttalswhicharerequiredby10CFR50,AppendixG.

Contributors to this SE: P. N. Randall L. Lois T. Colburn Date: