ML20133Q064
| ML20133Q064 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/15/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20133Q060 | List: |
| References | |
| NUDOCS 8511010352 | |
| Download: ML20133Q064 (4) | |
Text
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'o UNITED STATES
~,h NUCLEAR REGULATORY COMMISSION WASHING TO N, D. C. 20555 k.'..../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 97 TO FACILITY OPERATING LICENSE NO. OPR-66 DUQUESNE LIGHT COMPANY OHIO EDISON COMPANY PENNSYLVANIA POWER COMPANY BEAVER VALLEY POWER STATION, UNIT NO.1 DOCKET NO. 50-334 INTRODUCTION By letter dated July 12, 1985 (Ref. 1), Duquesne Light Company requested an amendment to the Technical Specifications of Beaver Valley Power Station, Unit 1.
Specifically, the amendment is to delete the rod bow penalty applied to the enthalpy rise hot channel factor specified in the Limiting Condition for Operation 3.2.3.
Our evaluation regarding this TS change follows.
DI SCUSSION AND EVALUATION The limiting Condition for Operation 3.2.3 of the Beaver Valley Unit 1 Technical Specifications specifies the allowable value of the nuclear N
enthalpy hot channel factor, F H, as a function of thermal power level.
3 In the same specification, the allowable FoH is further reduced by a penalty multiplier which is dependent on the magnitude of the rod bow penalty.
Figure 3.2-4 of the Technical Specifications specifies the value of the rod bow penalty as a function of fuel exposure.
Fuel rod bowing reduces the channel gap size between adjacent fuel rods which results in reduction in the critical heat flux (CHF) as well as the departure from nucleate boiling ratio (DNBR). Thus a rod bow penalty is applied tc the l
calculated DNBR.
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The Beaver Valley - 1 fuel design is the Westinghouse 17x17 standard fuel assembly with R-mixing vane grids.
The grid spacing span is roughly 20 inches.
The CHF and hence DNBR are calculated using the W-3 CHF correlation. W-3 was originally developed with the CHF data obtained with fluid flowing inside heater tubes and annuli. Based on the R-grid fuel rod bundle CHF data, Westinghouse later modified the W-3 correlation by applying a modified R-grid spacer factor and a correlation multiplier.
In the DNB design analysis, safety margin was increased by using a conservative correlation multiplier, DNBR limit, pitch reduction, and conservative values of thermal diffusion coefficient and axial grid spacing coefficient which affect the spacer factor. For the 17x17 standard R-grid fuel design, a generic margin of 9.1% DNBR has been quantified (Ref. 2) which can be used to compensate for the rod bow penalty on DNBR reduction.
If the generic margin is insufficient to cover the penalty, plant-specific reduction in the allowable F
is required to compensate for the DNBR reduction.
aH The fuel rod bow penalty calculation is described in the Westinghouse topical report WCAP-8691, Revision 1 " Fuel Rod Bow Evaluation" (Ref. 3). Prior to the approval of this topical report, the rod bow penalty was calculated using the NRC interim method, which resulted in a higher rod bow penalty than the generic margin. The rod bow topical report has since been approved (Ref. 4); the magnitude of rod bow penalty calculated with the approved method has been greatly reduced. For the Westinghouse 17x17 R-grid fuel assembly, the rod bow penalty is less than 3% at 33,000 MWD /MTU which is the maximum burnup of concern with respect to the rod bow penalty. This rod bow penalty of less than 3% is fully compensated by the generic margin of 9.1%.
Therefore, no rod bow penalty is required on DNBR as well as the allowable F The aH.
proposed removal of Figure 3.2-4 and the rod bow penalty multiplier on F"g 3
from the current Technical Specification LCO 3.2.3 is therefore acceptable.
The basis of Technical Specification 3/4.2.3 is also revised to reflect the l.
change in LC0 3.2.3.
The magnitude and source of the generic margin and the magnitude of rod bow penalty are also included in.the proposed bases. This revision provides clear accounting of the margin and penalty and is acceptable.
. Environmental Consideration This amendment involves a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, ancf that there is no significant increase in individual or cumulative occupational radiation exposure. The Comission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has. been no public coment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Sec 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance tha't the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Comission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
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REFERENCE S 1.
Letter from J. J. Carey (Duquesne Light Company) to S. A. Varga (NRC),
" Beaver Valley Power Station Unit No.1, Docket No. 50-334, License No. DPR-66, Proposed Operating License Change Request No. 110",
July 12, 1985.
.2.
Letter from E. P. Rahe, Jr. (Westinghouse) to J. R. Miller (NRC),
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" Remaining Response to Request Number 1 for Additional Information on WCAP-8691, Revision 1", NS-EPR-2572, March 16, 1982.
3.
WCAP-8691, Revision 1, " Fuel Rod Bow Evaluation", July 1979.
4.
Letter from C. Thomas (NRC) to E.P. Rahe (Westinghouse) December 29, 1982.
Dated:
October 15, 1985
,,[rincipal Contributor:
Gene Hsii
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