ML20215D987

Responds to 860917 Request for Review of Interpretations of Various Conditions for Use of ASME Code Case N-411-1.Design Response Spectra for Structures on Rock Not Satisfied for Use.Interpretation of Remaining Conditions Acceptable

ML20215D987
Person / Time
Site:	Millstone
Issue date:	12/09/1986
From:	Thadani A Office of Nuclear Reactor Regulation
To:	Opeka J NORTHEAST NUCLEAR ENERGY CO.
References
TAC-62859, NUDOCS 8612170175
Download: ML20215D987 (2)

Text

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- December 9, 1986 b Docket No. 50-336 DISTRIBUTION TMarsh (Docket y EJordan NKU FDR BGrimes L PDR JPartlow Mr. John F. Opeka, Senior Vice President PBD#8 Rdg NThompson Nuclear Engineering and Operations FMiraglia Gray File Northeast Nuclear Energy Company OGC DJaffe P. O. Box 270 ACRS-10 PKreutzer Hartford, Connecticut 06141-0270

Dear Mr. Opeka:

By letter dated September 17, 1986, you requested our review of the manner in which ycu intended to utilize ASME Code Case N-411-1 at Millstone Unit 2.

Your letter contained interpretations of the various conditions for use of Code Case N-411-1.

The NRC staff has reviewed your interpretation of the conditions as applicable to Millstone Unit 2. One of these conditions is that the damping values in code Case N-411-1 may be used only in analyses which are based on current seismic spectra and procedures, where current seismic spectra refers to the design basis spectra in Regulatory Guide 1.60, or properly justified site specific spectra. You have stated that the design response spectra for structures founded on rock are shown in Figures 5.8-1 and 5.8-2 of the FSAR.

The staff has determined that these spectra are less conservative than the Regulatory Guide 1.60 spectra for the same ZPA at all frequencies in the range of .4 Hz to 30 Hz. The staff has also reviewed FSAR Sections 2.6, Seismology, and 5.8.1.1, Design Response Spectra, and has determined that no basis for the derivation of the spectra in Figures 5.8-1 and 5.8-2 has been provided. (The design response spectra for structures supported on compacted structural backfill appear to correspond to the Regulatory Guide 1.60 spectra.) It must, therefore, be concluded that this condition is not satisfied for use of Code Case N-411-1 at Millstone Unit 2.

NNECO has also committed not to use Code Case N-411 damping values for cases "where inclusion of system response over 33 Hz would cause more than 10%

incremental increase in seismic response." The meaning of this statement needs clarification. Should NNEC decide to pursue this issue, further clarification of this position will be required. With regard to your interpretation of the remaining conditions for use of Code Case N-411-1 at Millstone Unit 2, we find these interpretations to be acceptable.

Sincerely, Ceigine.1 nigud WT ishok Thadanf Ashok C. Thadani, Director PWR Project Directorate #8 Division of PWR Licensing-B cc:

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Mr. John F. Opeka Millstone Nuclear Power Station Northeast Nuclear Energy Company Unit No. 2 cc:

Gerald Garfield, Esq. Mr. Wayne D. Romberg Day, Berry & Howard Superintendent Counselors at Law Millstone Nuclear Power Station City Place P. O. Box 128 Hartford, Connecticut 06103-3499 Waterfora, Connecticut 06385 Regional Administrator, Region I Mr. Edward J. Mroczka U.S. Nuclear Regulatory Commission Vice President, Nuclear Operatimas Office of Executive Director for Northeast Nuclear Energy Company Operations P. O. Box 270 631 Park Avenue Hartford, Connecticut 06141-0270 King of Prussia, Pennsylvania 19406 Mr. Charles Brinkman, Manager Washington Nuclear Operations C-E Power Systems Combustion Engineering, Inc.

7910 Woodmont Avenue Bethesda, Maryland 20814 Mr. Lawrence Bettencourt, First Selectman Town of Waterford Hall of Records - 200 Boston Post Road Waterford, Connecticut 06385 Northeast Utilities Service Company ATTN: Mr. Richard R. Laudenat, Manager Generation Facilities Licensing Post Office Box 270 Hartford, Connecticut 06141-0270 Kevin McCarthy, Director Radiation Control Unit Department of Environmental Protection State Office Building Hartford, Connecticut 06106 Mr. Theodore Rebelowski U.S. NRC P. O. Box 615 Waterford, Connecticut 06385-0615 Office of Policy & Management ATTN: Under Secretary Energy Division 80 Washinaton Street Hartford,' Connecticut 06106

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