ML20154B330
| ML20154B330 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/11/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20154B308 | List: |
| References | |
| NUDOCS 8805170151 | |
| Download: ML20154B330 (3) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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ENCLOSURE 1 SAFETY EVALUATION BY THF OFFICE OF NUCLEAR REACTOR REGULATION RFLATING TO ADDENDUM 2 TO NUSCO TOPICAL REPORT ON PHYSICS METHODOLOGY FOR PWR RELOAD DESIGN (NUSCO-152)
NORTHEAST UTILITIES SERVICE COMPANY MILLSTONE UNIT NO. 3 DOCKET NO. 50-423
1.0 INTRODUCTION
By letter dated November 13, 1987, Northeast Utilities Service Company (NUSCO), submitted Addendum 2 to NUSCO Topical Peport on Physics Methodology for PWR Reload Design (NUSCO-152) (Ref. 1).
This addendum summarizes the comparison of zero power physics data and the power measurements to predictions for Cycle 1 of Millstone Unit No. 3.
The staff reviewed NUSCO-152 and found the methodology acceptable for use by NUSCO to perfonn physics analyses for the Haddam Neck Plant (Ref. 2) only. NUSCO now requests approval to use the methodology for Millstone Unit No. 3.
2.0 EVALUATION Addendum 2 to Topical Report NilSCO-152 sumarizes the comparison of measurements to prediction for Millstone 3 Cycle 1.
The overall cuality of the data is very similar to that provided for Haddam Neck Cycles 12, 13 and
- 14. The two major sections of this addendum are the Zero Power Physics test data verification and the power distribution verification.
2.1 7ero Power Physics Test Verification The zero power physics tests consist of measurement of critical boron concentratien, isothermal temperature coefficient, control rod bank worth and ejected red worths, i
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ry d
The critical boron concentration was predicted at all rods out (ARO) and with Banks D, C, B and A inserted.
The difference between measured and predicted values varied from -6 ppm to -32 ppm with an average value of -23 ppm.
The acceptance criterion for these measurements is 1100 ppm.
The isothermal temperature coefficient was predicted and measured at three configurations. The deviation ranged from -0.11pem/*F to -0.68pcm/'F with an average deviation of -0.413pcm/*F. The acceptance criterion is apcm/*F.
Control rod bank worths were predicted ar.d reasured for 7 different configurations.
The deviations ranged from +3.04% to -3.83% with an absolute average difference of 2.93%.
2.2 Pcwer Distribution Verification Thirteen comparisons of predicted vs measured radial power distribution were shewn at various cycle exposures. The agreement between measured and predicted was excellent in all cases.
The average absolute difference for these comparisons was less than 1.0 percent in all cases and the standard deviation was less than 1.0 percent in all cases.
The comparisons of the axial power distributions also showed good agreement between measured and predicted values.
Peaking factors were also compared for the 13 cases.
The largest differences between measured and predicted F and F are about 1.7% and 5.9% respectively AH g
with average absolute differences of 0.44% and 2.16% respectively.
Comparisons were made between measured and predicted boron rundown values during cycle depletion. The greatest deviation was 51 ppm with the average difference of ?7 ppm.
For the axial offset comparison, the largest deviation was 4.88% with an average absolute difference of 1.4%.
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3.0 CONCLUSION
S We have reviewed the data submitted in Addendum 2 of Topical Report NUSCO-15?
and find that the measured and predicted values compare very well.
In most cases, the deviations were very similar to those from the Haddam Neck data, even thcugh, the amount of data was smaller.
Based on this review, we find that the methodology is acceptable for Ml'SCO to use for PWR physics analyses in support of plant cperation and licensing for the Millstone Unit 3 plant.
Because of the somewhat limited data base used, we recomend that NUSCO perfom periodic reevaluation of the model validity as new data becomes available to provide continuirp assurance of its applicability. NUSCO has comitted (Ref.
- 3) to perform a periodic reevaluation of its model validity. The test program and test review criteria used will be consistent with those in ANSI /ANS 19.61-1985 "American National Standard Reload Startup Physics Tests for Freisurized Water Reactors." We find this acceptable.
REFERENCES 1.
J. F. Opeka letter to C. I. Grimes /A. C. Thadani/V. S. Noonan, "Physics Pethodology for PWR Reload Design," dated September 12, 1986.
2.
F. M. Akstulewicz letter to E. J. Proczka, "Peview of Physics Methodology for PWR Reload Design (NUSCO-15?)," dated August 3,1987.
3.
E. J. Proczka (NUSCO) letter to NRC, dated April 4, 10P8.
Principal Contributor:
M. Chatterton Dated: Pay ll, 1988 i
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