ML20211P225
| ML20211P225 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 12/15/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20211P196 | List: |
| References | |
| REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR NUDOCS 8612190008 | |
| Download: ML20211P225 (2) | |
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UNITED STATES b
NUCLEAR REGULATORY COMMISSION j
j WASHINGTON, D. C. 20555 e
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING PROJECTED VALUES OF MATERIAL PROPERTIES FOR FRACTURE TOUGHNESS REOUIREMENTS FOR PROTECTION AGAINST PRESSURIZED THERMAL SHOCK EVENTS UNION ELECTRIC COMPANY CALLAWAY PLANT DOCKET NO. 50-483 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 RT surface) of reactor vessel beltline materials by g$vkng(at the inner vessel values from the tine 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 measure-ments or other information indicate a significant change in projected values."
By letter dated January 21, 1986, the Union Electric Company, licensee for the Callaway plant, submitted infornation on the material properties and the fast neutron fluence (E > 1.0 fleV) of the reactor pressure vessel in compliance with the requirements of 10 CFR 50.61 (Reference 1). The f!RC Staff reviewed the pressure vessel material properties and found them acceptable (Reference 2).
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 RTPTS
- EVALUATION OF THE MATERIAL ASPECTS The controlling beltline material from the standpoint of PTS susceptibility was identified to be the lower shell plate R2708-1.
The material properties of the certrolling material and the associated margin and chemistry factor were reported to be:
Utility Submittal Staff Evaluation CU (copper content, %)
0.08 0.08 Ni (nickel content, 7) 0.60 0.60 I (Initial RT F) 50 50 M (Margin,' fig, 48 CF (Chemistry Factor, *F) 44.4 8612190008 861215 PDR ADOOK 05000483 p
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The controlling material has been properly identified. The justifications given for the copper and nickel contents and the initial P,T are acceptable.
The irargin has been derived from consideration of the bases Mr these values, p
following the PTS Rule, Section 50.61 of 10 CFR Part 50. Assuming that the reported values of fluence are correct, Ecuation 1 of the PTS rule governs, and the chemistry facter is as shown above.
The trethodolgy of the fluence calculation was based on the oiscrete ordinates code DOT with an ENDF/B-IV based cross section set. The scattering is treated with a P approximation. However, a censervative 20% allowance was made for l
the flux estimate compared to a P estimate. An additional 70% was added for 3
uncertainties and another 20% for future core design changes. The total in-crease punts to a factor of 1.73 for a peak fast fluence (E > 1.0 MeV) of 2
3.63x10 n/cm. The methodology and the approximations used are acceptable.
The equation specified in 10 CFP 50.61, a ; applicable for the Callaway Plant is:
PTS = I+M+(-10+470xCu+350xCuxNi)xf.27 0
RT where:
I = Initial Rt
= 50*F N=Uncertianthargin
= 48 F Cu = w/o Copper in lower shell plate R2708-1
= 0.08 Ni = w/o Nickel in lower shell plate R2708-1
= 0.60 t = Peak Azimuthal Fgence fE > 1.0 MeV) lower shell plate R2708-1 in units of 10 n/cm = 3.63 Therefore, to the end of 32 effective full power years:
RT"b = 50+48+(-10+470x0.08+350x0.08x0.60 x3.63 27 0
= 96+44.4x1.416 = 160.9*F which is lcwer than 270'F, the applicable PTS rule screening criterion and is ecceptable.
It should be noteo that the above fluence represents less ther 2.5% of the fluence required to meet the 10 CFR 50.61 screening criterie.
In view of:
(a) the Pressure-Tenperature updateing requirements for the fracture toughness of the beltline material in 10 CFR 50 Appenoix G, and (b) the fact that the RT value is reaoily available from the calculation of the Pressure TenperaEu3e limits, and (c) the staff desirc to te irformed on the current value of the RT tor aH PTS
- PWRs, we request that the licensee submit a re-evaluation of the RT and a comparison to the prediction of Reference 1 along with the future PressurhTerroereture p
operating limits which are required by 10 CFR 50 Appendix G.*
It should be noted tFat this re-evaluation is a requirer.ent by 10 CFR 50.61, whenever core loadings, surveillance neasurements, or other information irdicate a significant change in projectea values.
Ints request for information is covered ur. der CFB clearance No. 3150-0011.
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