ML20062M391: Difference between revisions

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{{Adams
#REDIRECT [[B10327, Responds to NRC Re Probabilistic Safety Study. Study Will Satisfy Comparison of Facility to Other Plants by Use of Similar Yardstick Comparison & Verify Current Design & Procedural Changes.Completion Expected by Nov 1983]]
| number = ML20062M391
| issue date = 12/09/1981
| title = Responds to NRC 810921 Ltr Re Probabilistic Safety Study. Study Will Satisfy Comparison of Facility to Other Plants by Use of Similar Yardstick Comparison & Verify Current Design & Procedural Changes.Completion Expected by Nov 1983
| author name = Counsil W
| author affiliation = NORTHEAST NUCLEAR ENERGY CO.
| addressee name = Youngblood B
| addressee affiliation = NRC OFFICE OF NUCLEAR REACTOR REGULATION (NRR)
| docket = 05000423
| license number =
| contact person =
| document report number = AEC-MP3-254, B10327, NUDOCS 8112170201
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC
| page count = 3
}}
 
=Text=
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                                                                              ** Q sancny m IEI B. J. Youngblood, Chief                                                '85 8 '8 Licensing Branch No. 1                                        e f
Office of Nuc1 car Reactor Regulation                          4  j U. S. Nuclear Regulatory Commission                                0)        to Washington, D.C. 20555
 
==References:==
(1) Harold R. Denton letter to W. G. Counsil, Risk Evaluation, dated September 21, 1981.
(2)  W. G. Counsil letter to B. J. Youngblood, Pro-babilistic Risk Assessment, dated July 2, 1981.
(3)  R. L. Tedesco letter to W. G. Counsil, Class 9 Accident Analyses in the Environmental Report, dated August 3, 1981.
Gentlemen:
Millstone Nuclear Power Station, Unit No. 3 Probabilistic Safety Study In responding to Mr. Denton's letter, Reference (1), Northcast Utilities is interested in verifying the areas of mutual agreement that are necessary for the probabilistic safety study of Millstone Unit No. 3.
We find this verification to be necessary to ensure there is full understanding and agreement on the scope and scheduled completion for the Millstone Unit No. 3 Probabilistic Safety Study. Reference (1) did not reference or acknowledge our prior meeting and correspondence to the NRC, in which we provided a number of comments, recommendations and commitments.
We have proposed, in Reference (2), and still maintain that a November 1983 submittal date for the Probabilistic Safety Study is appropriate.
However, we will make every attempt to accommodr.te Mr. Denton's request, Reference (1), to complete and submit the study within six months fol-lowing the FSAR docketing.
By performing this study Northeast Utilities intends to satisfy two primary objectives. In Reference (1), the NRC Staff agrees with our first objective:  to have a study that will enable a comparison of Millstone Unit No. 3 to other plants by use of a similar yardstick comparison, namely WASH-1400. The second objective is solely that of Northeast Utilities:    to generate and maintain a living Probabilistic Safety Study to be used as a tool for verifying the safety of our cur-rent design, and for verifying of the safety of significant design or procedural changes in the future. This will help ensure protection of public health and safety. As a measure of acceptable risk we are d
8112170201 011209                                                                          I DR ADOCK 05000423 PDR                                                                            .
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[formulatinga'setofcorporatesafety_goalobjectivestobeused.as-
                .ourfacceptancel criteria. As stated in: Reference (2),-if it is deter -
1 mined that the plant does'not meet the acceptance. criteria, then the plant would_be modified to meet,it on a schedule arrived at with'due consideration to the level of deficiency found.-
In order to satisfy the second objective stated above, the Millstone Unit No. 3 Probabilistic Safety Study must be performed utilizing state-of-the-art technology. The NRC Staff =and Mr. Denton agree in
                - Reference (1), that 'significant improvements in probabilistic cechnology have been made since WASH-1400. Many.of:these improvements have been 4 addressed and documented in the PRA Procedures' Guide _under development.
                                                                                        ~
While we' concur with Reference. (1), that we. cannot -be sure that the final Procedures Guide will be issued timely enough for use in the Millstone Unit No. 3 Study, the recent review meeting on the.first. draft of NUREG-2300 has shown that the~ content of the Guide'is substanticily.
established and that the final Procedures Guide requires numeroer evi-ations from, and improvements-on, WASH-1400-technology. The r.
                                                            ~
                                                                                          ,will be finalized well before completion of the Millstone Unit Ns.          scudy..
Therefore, the. Millstone Unit No. 3 study will, in general, utilize WASH-1400' type methodology but may deviate from it wherever the Pro-cedures Guide recommends improvements over WASH-1400 technology for the sake of assuring-the technical quality of the study. Deviations from WASH-1400 methodology are also required to address external eventa, since WASH-1400 did not include the effect of external events.
Our Probabilistic Safety Study will consist of three major assessments.
                .The first two of these will be submitted to the NRC on or before-November 1983. The third assessment is intended to be a continuing process for all significant plant improvements that may occur in the future. These assessments are:
o    A Probabilistic Safety Study of Millstone Unit No. 3 compared against the WASH-1400 base PWR evaluation, considering plant specific design and site differences. In order to allow a one-to-one comparison of the two plants, the Millstone Unit No. 3 Study, used for this comparison, will not include the effect of external events.
o A Probabilistic Safety Study of Millstone Unit No. 3 with the consequence analysis modified to include the effect of the
                        . external event initiators included in Attachment 1 to Reference (1).
                    .o    A Probabilistic Safety Study using methodologies as described lln Reference (2), evaluated against our corporate safety goal objectives.
As stated in Reference (2) we have committed to submitting a Probabiliste Safety Study- e47h would be referenced in the ER.      As such, Northeast Utilities will be meeting the Commission's. Statement of Interim Policy dated -June 13,1980, (45 FR 40101) . . Additionally, we understand that-1 f
 
      -w .: (
in performing ~this study for Millstone Unit No. 3 the staff agrees that.
a late.c NREP study will'not be required.
The above summaries constitute our resolution and agreement on the -
commitments' we can meet to satisfy your objectives for a Probabilistic Safety Study. Unless we hear otherwise we assume NRC concurrence and will proceed accordingly.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY W. G. Counsil Senic: Vice President cc:    H. R. Denton                                                      ,
R. L. Tedesco J.-Grant 4 -}}

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