ML18044A458

Corrected Copy of Ltr Indicating Info Prepared by Exxon Nuclear Co,Inc Re Compliance W/Newly Proposed NRC Clad Swelling & Rupture Models.Applies to Both Units

ML18044A458
Person / Time
Site:	Palisades, Big Rock Point  File:Consumers Energy icon.png
Issue date:	01/21/1980
From:	Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Zieman D Office of Nuclear Reactor Regulation
Shared Package
ML18044A455	List: ML18044A454 ML18044A458
References
NUDOCS 8001250511
Download: ML18044A458 (7)

Text

• .

consumers

• Corrected cop~eissued 1/21/80 to correct title block only.

Power company-General Offices: 212 west Michigan Avenue, .Jackson, Michigan 49201

• Area Code 517 788-0550 January 16, 1980 Director, Nuclear Reactor Regulation Att Mr Dennis L Ziemann, Chief Operating Reactors Branch No 2 US Nuclear Regulatory Commission Washington, DC 20555 DOCKETS 50-155 AND 50-255 - LICENSES DPR-6 AND DPR~20* -

BIG ROCK POINT AND PALISADES PLANTS - FUEL CLAD SWELLING AND RUPTURE DURING A LOCA In response to the NRC letter of November 9, 1979 concerning fuel cladding swelling and rupture during a LOCA, Consumers Power Company has reviewed.the documentation submitted by our fuel vendor (Exxon Nuclear Company). This review was done in conjunction with the staff's new fuel cladding swelling and rupture models to verify the correctness of the representations made in our behalf.

• As a result of our review, there is one area in which it was not clear that the generic analysis by our vendor was bounding with respect to fuel used in the Palisades Plant. A Plant Specific Analysis of the effects of the staff's models on the LOCA analysis was requested from ENC. The results of this analysis have been reviewed by Consumers Power Company. Consumers Power Company concurs with the conclusion that the use of the staff's model reduces calculated peak cladding temperatures for all PaliSades fuel types, and that, therefore, the previous ECCS calculations for the Palisades Plant are conservative and continue to be valid.

The manner in which this problem was handled is of great concern to Consumers Power Company. Having *reviewed the Draft Report NUREG-0_630, it can be understood that the staff's new clad swelling and flow blockage model is a useful empirical correlation. It is also understandable that the model is, of necessity, based upon several nonrigorous engineering judgments and, to a significant degree, nonprototypical data .. It is not understood why previously approved empirical correlations, like those of ENC, should be compared to the staff'*s empirical model rather than to the set of all experimental data. In this instance, the ENC correlation was found to be more conservative than the*

soo1250_ s-. l/

• Corrected copy, reissued 1/21/80 to correct title block only.

2 staff model. Consumers Power Company is concerned, however, that future NRC requests of this type could unnecessarily create a licensing problem if an empirical correlation is found to be slightly less conservative in comparison to a staff model even though it adequately bounds ,all experimental data.

David P Hoffman (Signed)

David P Hoffman Nuclear Licensing Administrator CC JGKeppler, USNRC Enclosure

CONSUMERS POWER COMPANY BIG ROCK POINT and PALISADES PLANTS Dockets 50-155 and 50-255 Licenses DPR-6 and DPR-20 At the request of the Commission and pursuant to the Atomic Energy Act of

. 1954 and the Energy Reorganization Act of 1974, as amended, and the Commission's Rules and Regulations thereunder, Consumers Power Company submits the attached information prepared by Exxon Nuclear Company, Inc regarding compliance vith 10 CFR 50.46 in light of newly proposed NRC clad swelling and rupture models. Consmners Power Company has reviewed the in-formation prepared by Exxon Nuclear Company, Inc and concurs vith the con-clusions presented therein.

• CONSUMERS POWER COMPANY By: R B DeWitt (Sill!led)

RB DeWitt, Vice President Nuclear Operations Sworn and subscribed to before me this 16th day of JanuarJ, 1980.

Dorothy H Bartkus (Signed)

Dorothy H Bartkus, Notary Public Jackson County, Michigan My commission expires March 26, 1983.

ATTACHMENT I TO CONSUMERS POWER COMPANY AFFIRMATION OF JANUARY 16, 1980 EFFECT OF PROPOSED NRC CLAD SWELLING AND RUPTURE MODEL ON PALISADES ECCS ANALYSES In response to NRC concerns, this letter provides specific information on the impact of the newly proposed NRC Clad Swelling and Rupture Model(l) on ENC's ECCS analyses for Palisades. Use of the NRC model is found to reduce calculat-ed peak cladding temperatures (PCTs). Hence, prior ENC ECCS calculations for Palisades are conservative and continue to be valid.

The change in calculated PCTs when the NRC model for clad swelling and rupture is used in place of the ENC model is given in Table l for the applicable fuel types. The calculations are for the ENC CD=O. 6 DEG/PD limiting break at Palisades ( 2 , 3 ). The calculations were made for the limiting applicable exposure for each fuel type. Thus, for ENC TyJ>e E/G fuel and Combustion Engineering TyJ>e D fuel, both which have one or more cycles of exposure, the limiting caseconsidered is end-of-life exposure( 4 ). For the new ENC Type H fuel, the applicable limiting case is beginning-of-life. The present sensi-tivity calculations were made in accordance vi th ENC' s approved WREM-II PWR ECCS Evaluation Mode1(5, 6). The fuel rod internal pressure corresponds to the ENC model( 7 ) for nominal conditions. In view of the reduced PCT with the NRC clad swelling and rupture model, the current linear heat generation rate limits at Palisades insures conformance to 10 CFR 50.46.

References

l. D. A. Powers a.nd R. 0. Meyer, "Cladding Swelling a.nd Rupture Models for LOCA An~ysis", Draf't NUREG-0630, November 8, 1979.

2. "LOCA Analysis for Palisades at 2530 MWt Using the ENC WREM-II PWR ECCS Evaluation Model", XN-NF-77-24, July, 1977 tra.nsmi t.ted to NRC by Consumers Power Company letter dated July 28, 1977.

3. "LOCA Analysis of Palisades Type D Fuel at 2530 MWt Using the ENC WREM-II PWR ECCS Evaluation Model", XN-NF-77-24, Supplement 1, August, 1977 trans-mitted to NRC by Consumers Power Company letter dated August 17, 1977.

4. Letter, R. J. Ehlers (ENC) to W. J Beckius (CPCo), "Fission Gas Release Study and Uncertainty Analyses for Palisades Batch D and E Fuels" , March 20, 1978. Information provided by this letter was transmitted to NRC by Consumers Power Company letter dated May 23, 1978.

5. "Exxon Nuclear Company WREM-Based Generic PWR ECCS Evaluation Model",

XN-75-41:

a. Volume I, July, 1975

b. Volume II, Atigust, 1975

c. Volume III, Revision 2, August, 1975

d. Supplement 1, August, 1975

e. Supplement 2, August, 1975

f. Supplement 3, August, 1975

g. Supplement 4, August, 1975

h. Supplement 5, Revision~ 5, October, 1975

i. Supplement 6, October, 1975

j. Supplement 7, November, 1975

6. "Exxon Nuclear Company WREM-Based Generic PWR ECCS Evaluation Model Update ENC WREM-II", XN-76-27, July, 1976; Supplement 1, September, 1976; Supple-ment 2, November, 1976.

7. "Flow Blockage and Exposure Sensitivity Study for ENC D. C. Cook Unit 1 Reload Fuel Using ENC WREM-II Model", SN-76-51; Supplement 1, January, 1977; Supplement 2, February, 1978; Supplement.3, April, 1978.

I Effect of NRC Rupture and Flow Blockage Model on ENC ECCS Analyses for Palisades Fuel Type ENC Reload H ENC Type E/G C.E. Type D Peak Pellet Exposure (MWD/MTM} o* 45,000 45,000 Heatup Rate at Rupture (°C/S} 7.0 2.0 3.0 e:

PCT Impact of NRC Model. versus ENC Mode 1 -2?°F _goF -11°F

ATTACHMENT II to CONSUMERS POWER COMPANY AFFIRMATION OF JANUARY 16, 1980 EFFECT OF PROPOSED ~me CLAD SWELLING AND RUPTURE MODEL ON BIG ROCK POINT ECCS ANALYSES NRC letter dated November 9, *1979(1) requested that utilities evaluate the present ECCS clad swelling and rupture models in light of the proposed NRC clad swelling and rupture mode1(2), It was specifically requested that either the present clad swelling and rupture model be confirmed as in agree-ment or conservative vith respect to the NRC model over the range of interest or that results of calculations be presented which show the impact of the pro-posed NRC clad swelling and rupture model.

The ENC BWR clad swelling and rupture model has been compared to the propos-ed NRC temperature ramp rate dependent clad svelling and rupture model and found to be in agreement or conservative over the range of interest. The ENC BWR rupture temperature model al.ready has a temperature ramp rate dependence which is in agreement vith the proposed NRC rupture temperature model over the range of interest ( Trup t ure '7 9500).

• Over this same range of interest and at slov ramp rates typical of BWR ruptures, the rupture strain used in ENC BWR model for both heat transfer and oxidation (30%) is greater than or in agree-ment vith the rupture strain of the proposed ~me slow ramp rate model.

Because the ENC BWR clad swelling and rupture model is in agreement or is conservatiVe relative to the proposed NRC clad svelling and rupture model over the range of interest, it is concluded that the present ENC licensing analyses and current plant ECCS limits are in conformance vi th 10 CFR 50.46.

References

l. NRC letter from D G Eisenhut to operating LWR's dated November 9, 1979.

2. D A Powers and R 0 Meyer, "Cladding S\<elling and Rupture Models for LOCA Analyses", Draf't NUREG-06 30, dated No:vember 8, 1979.