ML19346A276
| ML19346A276 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 05/20/1981 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19346A273 | List: |
| References | |
| NUDOCS 8106050562 | |
| Download: ML19346A276 (5) | |
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NUCLEAR REGULATORY COMMISSION y
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's,*****f SAFETY EVALUATION BY THE OFFIC_E OF NUCLEAR REACTOR REGULATION SUPPORTING AftEN0 MENT NO. 79 TO FAJILITY OPERATING LICENSE NO. O PHILADELPHIA ELECTRIC COMPAf!Y PUBLIC SERVICE ELECTRIC AND GAS COMPANY DELMARVA POWER AND LIGHT COMPAfiY
' ATLANTIC CITY ELECTRIC COMPANY PEACH 60TT0t1 ATOMIC POWER STATION, UNIT NO. 2_
DOCKET NO. 50-277 1.0 Introduction By letters dated September 30,1980 (Ref.1) and May 14,1981 (Ref. 7), Philadelphia Electric Company (PECu or the licensee) made application to modify the Technical Specifications for Peach Bottom Atomic Power Station, Unit 2, to permit continued Cycle 5 operation.
The application contains a fuel-design-related change to revise Maximum Average Planar Linear Heat Generation Rate (MAPLHGR) to extend exposure limits.
2.0 Evaluation Exter.sion of MAPLHGR limits from 30 GHd/Scu to 40 GWd/StU was performed by methods (Ref. 2) submitted as part of this application. Although the methodology used is generally applicable for this MAPLHGR extension, we believe that the effects of enhanced fission gas release in high burnup fuel (above 20 GWd/MtU) were not adequately considered. Considering these effects, we have recommended a reduction in the proposed liAPLHGR values. The reduction is based on the results of comparative General calculations (Ref. 3) of fuel volume average temperature perfomed by(Ref. 5) for Electric using GEGAP-III (Ref. 4) with and without an NRC correction burnup enhanced fission gas release.
In calculating the f%PLHGR reduction, we conservatively assumed the change in volume-average temperature can be translated directly into a peak cladding temperature (PCT) change. An additional correlation between the increase in PCT and the increase in MAPLHGR was also taken from Reference 3.
Table 1 gives the percent reduction in 1%PLHGR as a function of burnup above 20 GWd/StU.
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, TABLE 1 REDUCTION IN MAPLHGR AS A FUNCTION OF EXPOSURE Burnup (GWd/Stu)
<30 30 32 34 36 38 40 MAPLHGR Reduction (%)
Unpressurized Fuel 0
6.3 12.5 16.5 23.5 30.3 40.0 Pressurized Fuel 0
3.0 6.0 8.4 10.8 13.5 16.5 Although a reduction could be calculated for fuel with local burnups as low as 20 GWd/MtU, previously approved MAPLHGR linits have been accepted for burnups below 30 Gid/StU (Ref. 6). The reduction, therefore, is applied only for burnups above 30 Gid/StU.
The MAPLHGR reductions have been incorporated into the licensee's revistd proposed Technical Specifications for Cycle 5 in Reference 7.
This change assures that the cladding temperature and local cladding oxidation would remain below the 2200*F PCT and the 17% local cladding oxidation limits allowed by 10 CFR 50.46 when the effects of enhanced fiesion gas release above 30 GWd/Stu are accounted for.
There are two significant changes in the application of MAPL *4GR reductions to Peach Bottom Unit 2.
First, the application is valid for p!anar average burnups as higi as 40 GWd/StU, rather than 36 GWd/StU as requested for other boiling water reactors (BWRs) with General Electric safety analysis. Second, the application modifies MAPLHGR limits for fuel type 80274H, which were previously accepted (Ref. 8) for exposures above 30 Gid/StU.
It is also noted that !%PLHGR limit s for 7x7 fuel have previously been accepted for exposures above 30 3d/StU. There is currently no fuel of the 7v7 design in Peach Bottom Unit 2.
As is the case for other GE-fueled BWRs, we have allowed credit for the difference between calculated PCT and the 2200*F limit of 10 CFR 50.46 to offset MAPLHGR reduction penalties. This 13 accomplished in the following manner: The value of MAPLHGR reduction at 15 GWd/StU.by interpolation of Table 1 is 18.5%. From Reference 2 (Table 9-3c) PCT at 35 Gid/Stu fo:-
80274L fuel with a MAPLHGR limit of 10.0 KW/ft is 1664*F. Thus, giving 1%
credit for every 20*F difference in PCT (between E200*F and 1664'F), the value of the IMPLHGR reduction at 35 GWd/StU is zero. Thus, the licensee's revised Technical Specification value (Table 4-3c of Ref. 2) for 8D274L fuel is unchanged at 35 GWd/Stu. A similar calculation is performed for other fuel types and other burnups in the Cycle 5 core. Tiet MAPLHGR reductions are calculated for most fuel types at 40 Gid/StU. These reductions have been incorporated into the licensee's revised proposed Technical Specificatiers.
Accordingly, we conclude that the proposed MAPLHGR versus average planar exposure values are acceptable.
2
1 Table 4-3 of Reference 2 contains MAPLHGR limits to 50 GWd/StU for one j
fuel type, LTA260. These f%PLHGR limits -apply to only four extended burnup i
lead test assemblies described in Reference 9.
Cnrrecting the !%PLHGR limits in the 40-50 GWd/StU range is not practical ty the same method used in the 30-40 GWd/Stu range. As a result, the licensee has not applied a
!%PLHGR correction for these four assemblies in the core. We believe that the licensee's decision to use an uncorrected analysis for these four assemblies is acceptable because, (a) he allowable power rating of these assemblies at high exposures is signirkantly lower than the rest of the core, (b) only four lead test bundles are involved, and (c) the benefits to be derived from this high-burnup lead test assembly program outweigh.
the small risk that will be taken by relying on an uncorrected analysis. We conclude that the licensee's safety analysis (Refs. 2 and 9) as related to Peach Bottom 2 Cycle 5 extended operation adequately considers the effects of operation with the proposed extended burnup lead test assenblies.
3.0 Environmental Considerations We have detemined that the amendrent does not authorize a change in effluent types'or total amounts nor an increase in power level and will not result in any signi#icant environmental impact. Having cade this determination, we have further concluded that the amendment involves' an action which is insionificant from the standpcint of environmental impact and, pursuant to 10 CFR 551.5(d)(4), that an environmental impact statement, or ner "e declaration and environ ~
mental impact appraisal need not be pr
.ed in connection with the issuance of this amendment.
There is, however, an environmental consideration related to the amendnent.
10 CFR 51.20g(2)(iii) states, "The average level of irradiation of the l
irradiated fuel from the reactor does not exceed 33,000 megawatt days per metric ton and...". The Technical Specification curves specify burnup in megawatt days per short ton. A short ton is 2,000 pounds and a metric ton is 2,205 pounds, thus a metric ton is 1.1 times greater than a short ton.
In a previous Safety Evaluation perfomed for the Browns Ferry Nuclear Plant, Units Nos. I and 2, dated October 6,1980, we extended the irradiation to 40,000 megawatt days per short ton. This is the same request made by PECo for Peach Bottom Unit No. 2 in this amendment. We found that the Browns Ferry fuel when irradiated to 40,000 megawatt days per short ton did not exceed an average level of burnup of 33,000 megawatt days per metric ton.
j The Peach Bottom 2 fuel is bounded by the evaluation done for the Browns Ferry fuel. We conclude, based on the bounding Browns Ferry analysis, that the i
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proposed bumups to 40,000 WD/Short Ton do not exceed the 10 CFR Part 51.20 limits of 33,000 f410/Catric Ton.
To assure that the environmental considerations in 10 CFR 51 are evaluated I
if MAPLHGR limits are extended in the future, we have with the licensee's concurrence, added a note to Technical Specification Figures 3.5.1.C and 3.5.1.0, stating the requirement in 10 CFR 51.20.
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l 4-Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease ir. a safety margin, the acendment does not involve a significant hazards consideration (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the commoh defense and security or to the health and safety of the public.
Dated: M4y 20,1981 6
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REFERENCES 1.
E. J. Bradley (PECo) letter to H. R. Denton (NRC), dated September 30, 1980.
2.
" Loss-of-Coolant Accident Analysis Report for Peach Bottom Atomic Power Station Unit 2", General Electric Company Report NED0-24081, December 1977 (with Addenda 1-6).
3.
R. B. Elkins, " Fuel Rod Prepressurization, Amendment 1", General Electric Company Report NEDE-23786-1-P, May 1978.
4.
"GEGAP-III: A Model for the Prediction of Pellet-Cladding Thennal Conductance in BWR Fuel Rods", General Electric Company Report NEDC-20181, November 1973.
5.
R. O. Meyer, C. E. Beyer and J. C. Voglewede, " Fission Gas Release from Fuel at High Burnup", U. S. NRC Report NUREG-0418, March 1978.
6.
T. A. Ippolito (NRC) letter to J. M. Pflant (Nebraska Public Power District) on Cooper Nuclear Station dated January 30, 1981.
7.
M. J. Cooney (PECo) letter to J. F. Stolz (NRC) dated May 14, 1981.
8.
R. W. Reid (NRC) letter to E. G. Bauer (PECo) dated June 13, 1980.
9.
" Lead Test Assenbly Supplemental Information for Reload 1 Licensing Submittal for Peach Bottom Atomic Power Station Unit 2", General Electric Company Report NED0-21172, Revision 1, Supplement 1, March 1976.
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