ML20116E700
| ML20116E700 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 06/22/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20116D885 | List:
|
| References | |
| FOIA-96-237 NUDOCS 9608060088 | |
| Download: ML20116E700 (3) | |
Text
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NUCLEAR REGULATORY COMMISSION I
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WASHINGTON,0. C. 20555
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ENCLOSURE 1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO THE FAST NEUTRON FLUENCE TO THE REACTOR PRESSURE VESSEL BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS UNIT 1 DOCKET NO. 50-317
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1.0 INTRODUCTION
1 The Baltimore Gas and Electric Company, i.e., the licensee for the Calvert Cliffs Unit 1 plant, comunissioned Southwest Research Institute (SwRI) for a new study of the pressure vessel embrittlement to be used in the determination of thepressure-temperaturelimits(AppendixG)andthelongterm(pressurized thermal shock) requirements of 10 CFR 50.61. The Materials Engineering Branch has the primary responsibility for this review and requested SRXB to review l
the fast neutron fluence calculations, i.e., Section 4 and Appendices A, B, and C of the SwRI study. Our review and evaluation follows.
2.0 EVALUATION b.
l The first fast neutron fluence pressure vessel surveillance capsule at Calvert Cliffs I was removed after Cycle 3 and the final report was issued in December 1980. The present calculations take a global view of the reactor, reevaluating the past cycles and extending the pressure vessel exposure to the end of current license at 32 effective full power years.
l The new elements in this reevaluation are:
(a) the new analytical tools DOT-4 (Ref. 1) and the SAILOR cross section set (Ref. 2) and (b) the licensee made an extrapolation to low-low leakage 24-month fuel cycles. The first 4 cycles I
were out-in refueling high leakage 12-months each. Cycles 5-9 were low leakage I
18-months; and beginning with Cycle 10, 24-months low-low leakage cycles will be used to the end of the current license, i.e., 32 effective full power years.
9608060088 96d731
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The two-dimensional DOT-4 code was used for the radial-azimuthal (R,8) flux distribution. The radial axial (R, Z) variation was treated with a synthesis method. An 5 angular quadrature and a P cross section expansion were used 8
3 with the SAILOR cross section set, which is based on ENDF/B-IV. The surveillance capsule was included in a detailed modeling. Similarly five group cross sections were obtained from ENDF/8-IV for the evaluation of the dosimeter Cu-63 (g,=) Co-60. This methodology satisfies all of our requirements for fluence calculations and is acceptable.
The results (shown at intervals of 4 years) estimate the peak pressure vessel fluence to the end of life. As an added verification the estimate of the surveillance capsule was very close (within 4%) of the measurement.
Therefore, (provided that the assumption of the 24-month cycle is kept) we find the 32 effective full power year peak fluence estimate to be acceptable.
3.0
SUMMARY
AND CONCLUSIONS We have reviewed the methodology and the results presented for the fast neutron fluence estimate of the Calve {t Cliffs Unit 1, for application related toAppendixG(pressure-Temperaturelimits)and10CFR50.61(pressurized thermal shock) and found them acceptable, because they comply with stafb requirements for such calculations.
4.0 REFERENCES
1.
ORNL-5851, "An Updated Version of the DOT-4 One and Two-Dimensional Neutron / Photon Transport Code" by W. A. Rhodes and R. L. Childs, ORNL, July 1982.
2.
DLC-76, " SAILOR-A Coupled Cross Section Library for Light Water Reactors" by G. L. Simons and R. Roussin, RSIC.
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ENCLOSURE 2 I
SYSTEMATIC ASSESSMENT OF LICENSEE PERFORMANCE i
FACILITY NAME Calvert Cliffs, Unit 1 l
SUMMARY
OF REVIEW This review was limited to Section 4 and Appendices A, B, and C of a SwRI report on the pressure-temperature limits for the Calvert Cliffs Unit 1.
This section described the methodology and the results for fast neutron transport calculations, which are in SRXB's area of review responsibility.
NARRATIVE DISCUSSION OF LICENSEE PERFORMANCE - SAFETY ASSESSMENT / QUALITY I-VERIFICATION The report was excellent and addressed the short and long term problems of the pressure vessel embrittlement, i.e., Appendix G and 10 CFR 50.61. Licensee performance is excellent.
l AUTHOR:
L. Lois l
DATE:
6/20/90 l
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