ML20206J092
| ML20206J092 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 06/16/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20206J089 | List: |
| References | |
| TAC-60291, TAC-60292, NUDOCS 8606260412 | |
| Download: ML20206J092 (4) | |
Text
.
j#*'%['t UNITED STATES e-NUCLEAR REGULATORY COMMISSION 8 i,@ ! j WASHINGTON, D. C. 20555 s.; ~lf E
o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 64 TO FACILITY OPERATING LICENSE NO. NPF-2 AND AMENDMENT NO. 57 TO FACILITY OPERATING LICENSE NO. NPF-8 ALABAMA POWER COMPANY JOSEPH M. FARLEY NUCLEAR PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-348 AND 50-364 INTRODUCTION By letter dated November 27, 1985, as supplemented April 11, 1986, (References 1 and 6), Alabama Power Company, the licensee, proposed deleting the rod bow penalty (RBP) currently included in the Technical Specifications (TSs) for Farley Nuclear Plant Units 1 and 2.
An analysis was provided to support the removaloftheRBgwhichwasusedincalculationsofthenuclearenthalpyhot channel factor, F The April 11, 1986, licensee letter provided additional informationandck$r.ification to the TS Bases section for completeness.
Our evaluation follows:
EVALUATION The rod bow penalty is currently addressed in thg TSs by a modifier to the equation for calculating the limiting value of F The modifier, [1-RBP(BU)],
hasatermforrodbowpenaltywhichisobtained$r.om TS Figure 3.2-3 showing the rod bow penalty as a function of core region average burnup.
The DNBR effects due to rod bow were studied by the Westinghouse Electric Corporation and the effects of predicted rod bowing on power peaking and DNBR analyses were presented for NRC review in a report, " Fuel Rod Bow Evaluation" (WCAP-8691), in January 1976.
Revision 1 of WCAP-8691 (Reference 2) and References 3 and 4 document subsequent NRC inquiries and Westinghouse responses.
The Westinghouse methods for predicting the effects of rod bow on DNB as described in the above documents were approved by the NRC staff in a letter to E. P. Rahe dated December 29, 1982 (Reference 5).
The licensee used the approved methods of Reference 4 for calculating the rod bow penalty and stated that the rod bow penalty is less than 3% at 33,000 MWD /MTU.
The licensee has also identified margins totaling 9.1% DNBR to accommodate full and low flow DNBR penalties associated with rod bow. The 9.1%
DNBR margin has been previously accepted for other similar Westinghouse plants (e.g. Summer) and is shown in the tabulation below:
860626 PDR 4
860616 P
05000348 PDR
DNB Margin %
a.
Design limit DNBR of [1.30 vs. 1.28],
1.6 b.
Axial Grid Spacing Coefficient (K )
f s
[0.046 vs 0.059],
2.9 c.
Thermal Diffusion Coefficient of
[0.038 vs. 0.059],
- 1. 2 d.
DNBR Multiplier of [0.865 vs. 0.88]
1.7 and e.
Pitch reduction 1.7 Total 9.1%
This margin is adequate to offset all rod bow penalties for assembly average burnups of up to 33,000 MWD /MTU.
The maximum rod bow penalty accounted for in the design safety analysis is less than 3% and is based on an assembly average burnup of 33,000 MWD /MTU.N At burnups greater than 33,000 MWD /MTU, credit is taken for the effect of F burndown.
This is due to the decrease in fissionable isotopes and the buildup N fission product inventory and therefore no additional rod bor penalty is required.
The staff finds the rod bow penalty of less than 3% acceptable as it is obtained using the approved methods of Reference 3.
Also, the generic DNBR margin of 9.1% which offsets the <3%
rod bow penalty is acceptable.
The licensee's proposed changes to the Technical Specifications for Farley Units 1 and 2 as a result of eliminating the rod bow penalty involve three pages:
3/4 2-8, 3/4 2-10 and B 3/4 2-4.
These changes are discussed as follows:
On page 3/4 2-8, Limiting Condition for Operation, TS 3.2.3, as currently exists rgfiects the equation for the limit of the nuclear enthalpy hot channel factor:
F 5 1.55 [1 + 0.3(1-P)][1-RBP(BU)]
AH THERMAL POWER and where P = RATED THERMAL POWER RBP(BU) = Rod Bow Penalty as a function of region average burnup as shown in Figure 3.2-3, where a region is defined as those assemblies with the same loading date (reloads) or enrichment (first cores).
The licensee has proposed that the multiplier [1-RBP(BU)] be deleted as well as the definition for RBP(BU).
These changes are acceptable as the rod bow penalty is no longer required as discussed abcve.
Page 3/4 2-10 currently contains Figure 3.2-3 (RBP) as a function of region average burnup. The licensee has proposed that this figure be deleted.
This change is acceptable because the deletion of the rod bow penalty in the TS 3.2.3 equation makes the figure of no further use.
Page B 3/4 2-4 is the Bases discussion of Power Distribution Limits.
The proposal modifies the previous TS Bases for the RBP by listing the five items from which generic design margins totaling 9.1% DNBR were obtained to offset the <3% rod bow penalty.
After NRC staff discussions, the licensee, in Reference 6, provided clarifying information to satisfy our concerns.
The 9.1% DNBR margin has previously been approved and the <3% rod bow penalty has been obtained by
)
approved methods.
i
- SAFETY
SUMMARY
We conclude that the proposed Technical Specification changes are acceptable and that the licensee may continue to operate the Joseph M. Farley I;uclear Plant, Units 1 and 2, at the rated power of 2652 thermal megawatts with the rod bow penalty removed.
This conclusion is based on the following: 1) acceptable methods were used for calculating the rod bow penalty and, 2) approved DNBR margin is available to offset the rod bow penalty.
ENVIRONMENTAL CONSIDERATION These amendments involve 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 amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously published a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding.
Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR SS1.22(c)(9).
Pursuant to 10 CFR 651.22(b),
no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.
CONCLUSION We have concluded, based on the censiderations discussed above, that:
(1) there is reasonable assurance that 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 m
Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated: June 16, 1986 Principal Contributors:
H. Balukjian E. A. Reeves
' 1 References (1) Letter from R. P. Mcdonald, Alabama Power Company, to Director, NRR, NRC, Attention:
L. S. Rubenstein, dated November 27, 1985.
4 (2) Skarita, J., (Ed), " Fuel Rod Bow Evaluation," WCAP-8691, Revision 1, July 1979, (Proprietary).
(3) " Partial Response to Request Number 1 for Additional Information on WCAP-8691, Revision 1" letter to E. P. Rahe, Jr., (Westinghouse) to J. R. Miller (NRC), NS-EPR-2515, dated October 9, 1981 (Proprietary).
(4) " Remaining Response to Request Number 1 for Additional Information on WCAP-8691, Revision 1" letter, E. P. Rahe, Jr., (Westinghouse) to J. R. Miller (NRC), NS-EPR-2572, dated March 16, 1982 (Proprietary).
(5) NRC letter from C. Thomas, NRC, to E. P. Rahe, Westinghouse dated-December 29, 1982.
(6) Letter from R. P. Mcdonald, Alabama Power Company, to Director, NRR, NRC, Attention:
L. S. Rubenstein, dated April 11, 1986.
--