ML20037C988
| ML20037C988 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/26/1981 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3, TASK-2.K.3.30, TASK-TM TAC-45859, NUDOCS 8104020541 | |
| Download: ML20037C988 (3) | |
Text
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esuuo SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 s street. Box 15830, sacramento, Califer..ia 95813; (916) 452 3211 3
March 26, 1981
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Director of Nuclear Reactor Regulation
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Division of Licensing
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U.S. Nuclear Regulatory Commission WM} 's Washington, D.C.
20555 Docket 50-312 Rancho Seco Nuclear Generating Station, Unit No. 1 TMI Action Plan, NUREG 0737 Item II.K.3.30
Dear Mr. Eisenhut:
NUREG 0737 requested the submittal of a detailed scope and schedule for a small break LOCA analysis by January 1, 1981. The Sacramento Munici'al Utility District advised you by letters dated-December 15, 1980 and Februari 26, 1981, of a meeting with the NRC Staff and the evaluation of a program proposed by the Babcock and Wilcox Company to the B & W Owners' Group. The Owners' Group Program is based on a review of the applicable NUREG documents and the information exchange which took place with your staff on December 16, 1980. The Sacramento Municipal Utility District has decided to participate in the B & W Owners' Group Program with the understanding, that there may be changes to this program during the course of the model development and veri-fication effort. At the present time the plan to make certain modifications to the existing model and to further justify.certain other parts of the model, is summarized below:
1.
Steam Generator Model Models will be provided in the CRAFT 2 code to more phenomologically account for the steam generator heat transfer due to the primary and secondary flow regimes, mixture levels and condensation in the presence of a non-condensible gas. This steam generator model, along with other models described 910w, will be used in a revised natural circu-M lation model. These models will be compared against LOFT test results.
S 2.
Pressurizer Model A 2-region non-equilibrium pressurizer model will be put in the CRAFT 2 code. The model will utilize fully-coupled conservation and state equations. The model will also provide for the pressurizer heater and spray actuation effects. The present surge line (no flooding) model will be justified.
This model will be compared to B & W plant transient data.
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.S Darrell G. Eisenhut Page 2 March 26, 1981 3.
Core Mixture Level and Heat Transfer Models Previous studies will be used to justify the core mixture level calculation. The ORNL high pressure core boiloff experiments will be used to justify the present heat transfer model.
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ECC Injection Model The sensitivity of the NSS to non-equilibrium ECC injection will be assessed. The enthalpy of the injected ECC fluid will be adjusted that local condensation and depressurization are reduced if necessary.
E Compensation would then be included to provide overall conservation of energy to account for the true injection enthalpy.
5.
Noding Model A noding sensitivity study for certain components of the RCS will be used in conjunction with previous experience in selecting a noding model for the entire system. This model will be checked sufficiently to ensure convergence and will also be compared against previous j
analyses.
6.
Break Flow Model A search of the literature will be performed to select a "Best Estimate" leak. flow model. Analyses will than be performed to compare the present model with the "Best Estimate". The objective will.t>e to show the present model to be adequate.
7.
Non-Condensible Gas Model All sources oof non-condensible gases will he accounted for including the radiolytic component. The radiolytic component will be determined with a model which accounts for the boiling in the core region.
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Two-Phe c flow Model A drift flux model will be included in CRAFT 2 as part of the L3-6 pre-diction. This model will be modified as necessary to permit simultaneous use of both ' drift flux and bubble rise models, with a junction between vertical and horizontal piping sections, i
9.
Reactor Coolant Pump Model NUREG-0623 contains a concern for the two-phase reactor coolant pump
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imodels. This concern is acknowledged here, however, this concern will l
be addres:ed as part of our responseito NUREG-0737, Item II.K.3.5.
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Darrell G. Eisenhut Page 2 March 26, 1981 M-revised model documentation will be provided ii a report to the NRC Staff by March 1, 1982.
In the meantime, if we can provide any further information, please advise.
Sincerely, hu1E u John J. Mattimce Assistant General Manager and Chief Engineer i