ML20138F884
| ML20138F884 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/11/1996 |
| From: | Sheron B NRC (Affiliation Not Assigned) |
| To: | Terry C TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| References | |
| TAC-M96355, NUDOCS 9610180098 | |
| Download: ML20138F884 (4) | |
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UNITED STATES g
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NUCLEAR REGULATORY COMMISSION 2
WASHINGTON, D.C. 20666-0001
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October 11, 1996 g
i Mr. C. Lance Terry TV Electric Group Vice President Nuclear Attn: Regulatory Affairs Department P. O. Box 1002 Glen Rose, TX 76043
SUBJECT:
10 CFR 50.46 LARGE BREAK LOSS-0F-COOLANT ACCIDENT EVALUATION MODEL FOR COMANCHE PEAK STEAM ELECTRIC STATION UNITS 1 AND 2 (TAC N0. M96355)
Dear Mr. Terry:
During August 1995, the Nuclear Regulatory Commission (NRC) met with Siemens Power Corporation (SPC) with regard to the large break loss-of-coolant accident (LBLOCA) evaluation model. As a result of that meeting, we sent a letter to SPC, dated November 13, 1995, which identified problems concerning changes in the model used by SPC for pressurized water reactors. This model was approved by the NRC staff to meet the requirements of 10 CFR 50.46 in the letter of July 8, 1986, from D.M. Crutchfield (NRC) to G. Ward (Exxon).
In the staff's letter of November 13, 1995, we stated that SPC had made changes to the NRC-approved Fuel Cooling Test Facility (FCTF) reflood heat transfer coefficient correlation used in the T00DEE2 computer code and did not properly assess the significance of the code changes.
It appears that the following two major changes were made to the FCTF correlation in the T00DEE2 code:
(1) some nonphysical non-monotonic behavior of the FCTF heat transfer coefficient correlation with respect to the reflood rate were eliminated and j
(2) the quench time calculation used in the model, using data from Cylindrical Core Test Facility (CCTF) experiments, was modified. By letter dated March 13, 1996, the staff requested SPC to address the changes to the T00DEE2 model and the code errors identified since July 1986.
On June 2,1996, SPC submitted topical report XN-NF-82-20, "EXEM/PWR Large Break LOCA ECCS T00DEE2 Updates," Revision 1, Supplement 5, which-described the updates made to the T000EE2 computer code since 1986. The staff has completed its review of this report and has concluded that the proposed LBLOCA-ECCS model (i.e.,1991 model) is not acceptable and the previous approved model (i.e., the 1986 model) has an unacceptable error in the model.
The staff's letter to SPC dated October 11, 1996, which includes the summary of conference calls with SPC on October 10 and 11,1996, on this matter, will be telecopied separately.
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Mr. C. Lance Terry 4 l
Because of the staff's conclusions regarding the unaccepability of the reflood heat transfer coefficient correlation used in the T00DEE2 computer code, we conducted a conference call on Thursday, October 10, 1996, with several licensees, including a representative of your plant. Other participants were representatives from Kewaunee Plant, Millstone Station Unit 2, Palisades Plant, Robinson Plant Unit 2, Shearon Harris Plant Unit 1, St. Lucie Plant l
Unit 1, and SPC. The purpose of the conference call was to inform each i
licensee that the staff had found changes in the unapproved 1991 LBLOCA l
evaluation model, which were intended to address problems with the approved 1986 model used by SPC for the LBLOCA and emergency core cooling system 4
j analyses, unacceptable.
In addition, the staff indicated that it will not accept LBLOCA analyses using the previously approved 1986 model unless that
)
j model adequately corrects the non-physical behavior observed in the reflood j
heat transfer correlation.
Therefore, in accordance with 10 CFR 50.46(a)(3)(ii), you should assess the impact of these model errors and changes and take whatever actions are required to assure compliance with 10 CFR 50.46.
Further, as you were informed in the conference call, the staff has scheduled a public meeting on October 16, 1996, at 1:00 pm, in 0-12B11, at its Headquarters Offices. The affected plants and SPC were requested to attend this meeting to present the results of their assessment of the peak cladding temperature for the LBLOCA and the corrective actions and compensatory measures that have been undertaken, both short-term and long-term, to assure plant compliance with 10 CFR 50.46.
J If you have any questions about this matter, please contact Timothy Polich at 301-415-1038, or Jack Donohew at 301-415-1307.
Sincerely, m td. % ~
Brian W. Sheron, Acting Associate Director for Technical Review Office of Nuclear Reactor Regulation Docket No.s 50-445 and 50-446 cc: See next page I
1 Mr. C. Lance Terry TV Electric Company Comanche Peak, Units 1 and 2 cc:
Senior Resident Inspector Honorable Dale McPherson U.S. Nuclear Regulatory Commission County Judge j
P. O, Box 1029 P. O. Box 851 Granbury, TX 76048 Glen Rose, TX 76043 Regional Administrator, Region IV Office of the Governor U.S. Nuclear Regulatory Commission ATTN:
Susan Rieff, Director 611 Ryan Plaza Drive, Suite 400 Environmental Policy Arlington, TX 76011 P. O. Box 12428 Austin, TX 78711 Mrs. Juanita Ellis, President Citizens Association for Sound Energy Arthur C. Tate, Director 1426 South Polk Division of Compliance & Inspection Dallas, TX 75224 Bureau of Radiation Control Texas Department of Health Mr. Roger D. Walker 1100 West 49th Street TV Electric Austin, TX 78756-3189 Regulatory Affairs Manager P. O. Box 1002 Glen Rose, TX 76043 Texas Utilities Electric Company c/o Bethesda Licensing 3 Metro Center, Suite 610 Bethesda, MD 20814 j
4 George L. Edgar, Esq.
Morgan, Lewis & Bockius 1800 M Street, N.W.
Washington, DC 20036-5869 J
Mr. C. Lance Terry October 11, 1996 DISTRIBUTION:
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PDIV-1 r/f FMiraglia/AThadani RZimmerman JRoe WBeckner BSheron GHolahan RJones TCollins LCallan (RIV)
TPolich' RScarano (RIV)
JDyer (RIV)
DPowers (RIV)
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Document Name:
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NAME JDon RZimmerma U
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DATE 10/ I/96 10/11/96 10/ll /96 10/II/96 i
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