ML20211P199

Safety Evaluation Supporting Util 860123 Response to PTS Rule.Matl Properties & Fast Neutron Fluence Calculations Acceptable Until End of Current License.Reevaluation of Rt (PTS) Required by 10CFR50.61

ML20211P199
Person / Time
Site:	Wolf Creek
Issue date:	12/15/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20211P188	List: ML20211P183 ML20211P199
References
REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR NUDOCS 8612190003
Download: ML20211P199 (3)

Text

• ~

gm UNITED STATES o,,

g NUCLEAR REGULATORY COMMISSION

, [ WASHINGTON, D. C. 20$55 5 ;j

\, * . . . . /

SAFETY EVALUATION BY THE OFFICE OF huCLEAR REACTOR REGULATIO REGARDING PROJECTED VALUES OF MATERIAL PROPERTIES

' FOR FRACTURE TOUGHNES$ REQUIREMENTS FCR PROTECTION AGAINST PRESSURIZED THERMAL SH0CK EVENTS KANSAS GAS AND ELECTRIC COMPANY WOLF CREEK GENERATING STATION DOCKET NO. 50-482 INTRODUCTION As required by 10 CFR 50.61, Fracture Toughness Requirements for Protection Against Pressurized Thennal Shock" (PTS Rule) which was published in the Federal Register July 23, 1985, the licensee for each operating pressurized l water reactor "shall submit projected values of RTsurface) values from the time The assessment of rea of submittal to the expiration date of the operating license.

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 measure-ments or other information indicate a significant change in projected values."

23, 1986, the Kansas Gas and Electric Company, licensee By letter dated Januaryfor the Wolf Creek Unit 1 plant, submitted information on th ties and the fast neutron fluence (E > 1.0 MeV) of the reactor pressure vessel The NRC in compliance with the reouirements of 10 CFR 50.61 (Reference 1).

staff reviewed the pressure vessel material properties and found them acceptable.

The following evaluation concerns the estimation of the fluence to the pressure vessel to the end of the current license and the corresponding value of the RT PTS

• EVALUATION OF THE MATERIAL ASPECTS The controlling beltline material from the standpcint of PTS susceptibility was identified to be the lower shell plate R2708-1. The material properties of the controlling material and the associated margin and chemistry factor were reported to be:

Utility Submittal Staff Evaluation 0.08 0.08 CU(coppercontent,%) 0.60 Ni (nickel content, %) 0.60 50 50 I (Initial RT F) 48 M (Margin, FIDT, --

-- 44.4 CF (Chemistry Factor, *F) 8612190003 861215 PDR ADOCK 05000482 P PDR .

The controlling material has been properly identified. The justifications are acceptable.

p given for the copper and nickel contents Assuming ano thethatinitial the RTThe following the PTS Rule, Section 50.61 of 10 CFR Part 50.

reported values of fluence are correct, Equation 1 of the PTS rule governs, and the chenistry facter is as shown above.

The nethodology of the fluence calculation was based The on the discrete is scattering ordinates treatec' ccde 00T with an ENDF/8-IV based cross section set.

with e P, approximation and S 6 angular quadrature was used. Statistical oper-ational Dower distributions for Westinghouse 4-loop plants were used for the extrapolation of the exposure to the end of the operating license (March 22, 2025) when the reactor will accumulate 31.74shell The lower effective full power plate R2508-3 has years beenof operation with an 807 lead factor. identified is the as peakthe of controlling the azimuthalmaterial, therefo

~ the fluence for the estimaticn of the RTThemethodology,thecorsENectionsand distrubution.

are acceptable.

The equation specified in 10 CFR 50.61, as applicable for the Wolf Creek plant is:

0 RT PTS = I+ti+(-10+470xCu+350xCuxNT)yf .77

= 40*F where: 1 = Initial Rt = 48"F M=Uncertiant[kargin = 0.07 Cu = w/o Copper in lower shell plate R2708-3 = 0.62 Ni = w/o Nickel in lower shell plate R2708-3 f = Peak Azimuthal Fgence {E > 1.0 MeV) lower shell plate R2708-3 in units of 10 n/cm = 3.14 Therefore, to the end of the current license:

0 7 RT PTS88+38.1x1.36

== 40+48+(-10+470x0.07+350x0.07x0.6

= 139.9'F which is lower than 270*F, the applicable PTS rule screening criterion and is acceptable. It should be noted that the above fluence represents less than 2.5% ef the fluence required to r:eet the 10 CFR 50.61 screening criteria.

In view of:

(a) the Pressure-Temperature updateing requireraents for the f racture toughness of the beltline material in 10 CFR 50 Appendix G, and value is reacily available from the calculatier of (b) the fact that the RT thePressureTemperaNqre limits, and PTS f r aH (c) the staff desire to be ir.fortred on the current value of the RT PWRs,

k p and a cocparison we request that the licensee submit a re-evaluation It should beof the RT crerating limits which are required by 10 CFR 50 Appendix G.*

noted that this re-evaluation is a requirenent by 10 CFR 50.61, whenever core loadings, surveillance measurenents, or other information indicate a significant change in projected values. [

REFERENCES

1. Letter fren G. L. Koester, Kansas Gas and Electric Company to Director, NRR dated January 23, 1986.

a 3150-0011.

• Ints request for information is covered uncer 0MB clearance No.

l l

l l

. ~ . . - . . . - , - - . .- , - - - ,- . - - - - - . -- - - .