ML20010G846
| ML20010G846 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/15/1981 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20010G847 | List: |
| References | |
| TASK-2.K.3.30, TASK-TM 743, TAC-45817, NUDOCS 8109220582 | |
| Download: ML20010G846 (3) | |
Text
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TOLEDO l
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Rc ano P. Cnots Docket No. 50-346 C"'*"'
License No. NPF-3 m a,as s.
Serial No. 743 September 15, 1981
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Director of Nuclear Reactor Regulation
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Attention:
Mr. John F. Stolz Operating Reactor Branch No. 4 44
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Division of Operating Reactors A
t%1 tad States Nuclear Regulatory Commission
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,d W=hingten, D.C.
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d Dear Mr. Stolz.
This is in response to Mr. R. W. Reid's letter dated February 24, 1981 (Log No. 663) to all Babcock & Wilcox Licensees concerning small break LOCA model to predict small break behavior. Our May 19, 1981 (Serial No. 709) response stated Toledo Edison would provide the post test evaluation of LOFT Test L3-1, and Semiscale Test S-07-10D, which are enclosed for Davis-Besse Nuclear Power Station Unit 1.
Babcock ar.d Wilcox. submitted the LOFT L3-6 test prediction to the NRC on behalf of the BW Owners Group (177 and 205 FA Plants) on March 20, 1981, which Toledo Edison endorses.
Mr. Reid's letter requested a response to tour questions concerning the dif-ference between the pretest predictions and the-test data. These quections are addressed in the enclosed reports and a summary of the responses is pro-vided below.
Question No. 1.
Evaluate the code predictive capability using initial and boundary conditions consistent with the actual test data.
Response
The evaluations provided demonstrate that the present small break analysis techniques result in good agreement with the test data when actual test conditions are con-sidered.
Question No. 2.
Identify code modifications and/or impros. aents necessary to predict the test data.
Response
No code modification and/or improvements were necessary to predict the experiments. However, as noted in the S-07-10D post test analysis, a more detailed core representation was necessary to provide a best estimate simulation of the experiment due to the er.-nsive core uncovery which occurred in the test.
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.s 8109220582 810915 DR ADOCK 05000346 PDR
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THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43052 l
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2-Question No. 3.
Assess whether any improvements and/or modi!! cations necessary for code predictions to agree with test data should be incorporated in present ECCS small break evalua-tion models.
Response
The core representation in the Evaluation Model gives conservative results when core uncovery occurs. The more detailed representation of the core need not be included in the Evaluation Model.
i Question No. 4.
Identify shortcomings in the test facility, instruments-t tion, etc., and their impact on code prediction capability, and recommend improvements to the test facility, instru-mentation, or test procedures to improve the verification process.
Response
In order to improve the verification process, a modified appro:c.h should be used for future tests. The " Blind Pre-Test" prediction should be eliminated 62e to the fact that significant deviations have existed la the past tests between the planned conditions and the actual test condi-tion. The predictions then become meaningless and a significant waste of money and manpower. Where appro-priate a " Blind Post-Test Prediction" could be implemented instead, using the actual test input data and conditions.
Following publication of test results from NRC, a " lost-Test Evaluation" may be necessary to verify the adequacy of tha model.
This letter, together with the attached reports, constitutes Toledo Edisre's reply to your February 24, 1981 request.
Very truly yours, k.f fW/
RPC/ GAB Attachment ks b/c cc: E3-1 NRC Resident Irspector 1
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