ML20216C884

Submits Clarification to 980406 Request for Concurrence W/Clarification & Understanding of SER for Siemens Power Corp EMF-85-74(P),Rev 0,Suppl 1 & 2, RODEX2A (BWR) Fuel Rod Thermal-Mechanical Evaluation Model

ML20216C884
Person / Time
Issue date:	05/14/1998
From:	Essig T NRC (Affiliation Not Assigned)
To:	Curet H SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER
References
PROJECT-702 TAC-M96729, NUDOCS 9805190430
Download: ML20216C884 (4)

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%y # May 14, 1998 Mr. H. D. Curet, Manager Product Licensing Siemens Power Corporation 2101 Horn Rapids Road P. O. Box 130 Richland, WA 99352-0130

SUBJECT:

TOPICAL REPORT "RODEX2A (BWR) FUEL ROD THERMAL-MECHANICAL l EVALUATION MODEL: FUEL ASSEMBLY EXPOSURE EVALUATION,"

EMF-85-74(P), REVISION 0, SER CLARIFICATION (TAC NO. M96729) i Ref.: 1 Letter, H. D. Curet to Shih-Liang Wu, April 6,1998.

Ref.: 2 Letter, T. H. Essig to H. D. Curet, " Acceptance for Reference of SPC Topical Report EMF-85-74(P), Revision 0, Supplement 1 and 2: RODEX2A (BWR) Fuel Rod Thermal-Mechanical Evaluation Model," February 9,1998.

(TAC No. M96726)

On April 6,1998, Siemens Power Corporation (SPC) transmitted a letter (Reference 1) to the NRC requesting NRC's concurrence with clarification and understanding of the safety evaluation report (SER) for SPC topical report EMF-85-74(P), Revision 0, Supplement 1 and 2: l "RODEX2A (BWR) Fuel Rod Thermal-Mechanical Evaluation Model." In the letter, you ,

requested the following points be clarified:

The January 1998 technical evaluation report (TER) and the safety evaluation report (SER), which is an enclosure to Reference 2, both concluded that (1) the RODEX2A code is acceptable for licensing applications to 62,000 mwd /MTU rod-average burnup and (2) the fuel rod l growth, fuel assembly growth, and fuel channel growth models and analytical metnods are acceptable for Atrium

• 9 and -10 fuel designs up to 54,000 mwd /MTU assembly-average burnup.

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Additionally, SPC agrees to comply with all conditions stated in Reference 2 of the TER which include, in summary, the following  ;

conditions: SPC is to account for the full effect of oxidation in fuel rod thermal-mechanical analyses with an enhancement in the RODEX2A A jkT 3 calculations for the corrosion analysis and fuel temperature analysis as committed to in SPC's letter NRC:98:004 dated January 16,g998.

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H. Curet May 14, 1998 The maximum wall thinning from oxidation will also be taken into account in the steady state stress analyses for end of life conditions.

No additional corrosion enhancement will be necessary for rod intemal gas pressure analyses performed to the approved exposure levels.

. The growth correlations that were reviewed and approved by the NRC may be applied to previous SPC 9x9 fuel designs. This clarification is justified because the growth correlations were derived from data that included SPC 8x8 and 9x9 designs.

. It is implied in Section 2.1 Cladding Strain of the TER, that the RODEX2A code is used for the transient strain analysis. This implication is not accurate. The use of the RODEX2 and RODEX2A codes is summarized in the following three points.1) The transient strain analysis is obtained from the version of the RODEX2 code referred to in Section 4.0 " Example Fuel Rod Design Analysis," Pellet-Cladding Integration of EMF-85-74(P),

Supplement 1, which is referenced in XN-NF-81-58(P)(A) Revision 2, Supplement 1, Response C.1.(b) to Question 7. The transient strain analysis has the reduced limit of 0.75% after a peak pellet exposure of 60 mwd /KgU. 2) The cladding steady state strain is calculated with RODEX2A in relation to a 1.0% limit. The 1.0% steady state limit is

, justified because it is a creep strain and is not subject to the same

! ductility limitations as the transient induced (elastic plus plastic) strain.

3) For overpower conditions the RODEX2A code is used to calculate fuel temperatures for the fuel melt analysis.

i a The RODEX2 code, (see XN-NF-81-58(P)(A) Revision 2 and Supplements 1 through 2,"RODEX2 Fuel Rod Thermal Mechanical Response Evaluation Model"), which is the base fuel performance code that interfaces with the SPC LOCA and transient thermal-hydraulic analysis methodologies, shall be applied to fuel designs with up to 62,000 mwd /MTU rod-average bumup and 54,000 mwd /MTU assembly-average bumup.

You have also requested that the following text quoted from the SER in Reference 2, be clarifed:

"For each application of the mechanical design criteria, SPC must document the design evaluation demonstrating conformance to these criteria and submit a i I

summary of the evaluation to the NRC staff for possible use in an audit to confirm that SPC is in compliance with these criteria."

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H. Curet May M,1998 in your letter, you stated that it was SPC's understanding that the above bulleted items and the text quoted from the SER in Reference 2 mean that SPC design fuel must (1) rneet the boiling water reactor (BWR) generic mechanical design criteria in the accepted topical report of Reference 2, (2) meet both approved bumup limits of 62,000 mwd /MTU rod-average and 54,000 mwd /MTU assembly-average, which supersede the previous 60,000 mwd /MTU peak pellet limit, and (3) provide the NRC staff, for possible audit, a summary report that confirms that SPC is in compliance with items (1) and (2).

The NRC staff finds that SPC's understanding of the above reiteration and clarification of the conclusions and the findings in the SER and the attached TER adapted by the NRC staff is correct. Please note that in addition to the SER for the Reference 2 topical report, this letter should be placed in the approved version of the topical report, " EMF-85-74(P)(A), Revision 0, Supplement 1 and 2: "RODEX2A (BWR) Fuel Rod Thermal-Mechanical Evaluation Model."

If you have any questions regarding this matter please contact Mr. Egan Wang of my staff by phone 301-415-1076 (email eyw@nrc. gov) or, Dr. Shih-Liang Wu at 301-415-3284 (email slw2@nrc. gov).

, Sincerely, Original Signed By:

Thomas H. Essig, Acting Chief Generic issues and Environmental l Projects Branch Office of Nuclear Reactor Regulation l Project No. 702

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H. Curet May 14, 1998 in your letter, you stated that it was SPC's understanding that the above bulleted items and the text quoted from the SER in Reference 2 mean that SPC design fuel must (1) meet the boiling water reactor (BWR) generic mechanical design criteria in the accepted topical report of Reference 2, (2) meet both approved burnup limits of 62,000 mwd /MTU rod-average and 54,000 mwd /MTU assembly-average, which supersede the previous 60,000 mwd /MTU peak pellet limit, and (3) provide the NRC staff, for possible audit, a summary report that confirms that SPC is in compliance with items (1) and (2).

The NRC staff finds that SPC's understanding of the above reiteration and clarification of the conclusions and the findings in the SER and the attached TER adapted by the NRC staff is correct. Please note that in addition to the SER for the Reference 2 topical report, this letter should be placed in the approved version of the topical report, " EMF-85-74(P)(A), Revision 0, Supplement 1 and 2: "RODEX2A (BWR) Fuel Rod Thermal-Mechanical Evaluation Model."

If you have any questions regarding this matter please contact Mr. Egan Wang of my staff by phone 301-415-1076 (email eyw@nrc. gov) or, Dr. Shih-Liang Wu at 301-415-3284 (email slw2@nrc. gov).

Sincerely, Original Signed By:

Thomas H. Essig, Acting Chief Generic issues and Environmental Projects Branch Office of Nuclear Reactor Regulation Project No. 702 DISTRIBUTION:

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(A)C:PGEh NAME - EWangIw' FAkstulewfc5 I TCollins TEssig [

DATE 04/28/98 (//k/98 6/l4/98 6 / 4/98 OFFICIAL RECORD COPY

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