ML20081K530
| ML20081K530 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 06/19/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20081K527 | List: |
| References | |
| NUDOCS 9106280076 | |
| Download: ML20081K530 (5) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGUtATION SUPPORTING AMENDMENT NO.137 TO FACILITY _0PERATING LICENSE NO. DPR-35 BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION DOCKET NO. 50-293
1.0 INTRODUCTION
By letter dated December 10, 1990 (Reference 1), Boston Edison, the licensee for Pilgrim Huclear Power Station (PNPS or Pilgrim), provided the results of the loss-of-coolant accident (LOCA) analysis for PNPS (GE Report, NEDC-31852-P, Reference 2) performed using General Electric Company's SAFER /GESTR-LOCA application methodology (Reference 3). The Pilgrim specific analysis will be used to demonstrate conformance with the emergency core cooling system (ECCS) acceptance criteria of 10 CFR Part 50 and the SAFER licensing methodology.
Additional ir, formation related to the LOCA analysis for PNPS was provided by letter dated May 2, 1991 (Reference 4).
By letter dated February 6,1991 (Reference 5), the licensee proposed a Technical Specification (TS) modification which identifies the reference to the LOCA analyses report.
The staff has reviewed the submittals and has prepared the following evaluation.
2.0 EVALUATION The LOCA analyses for plant reloads for PNPS were performed using the SAFER /GESTR code package and the application methodology described in Reference 3.
The staff's Safety Evaluation in Reference 6 specifies the necessary conditions for demonstrating applicability of the generic SAFER /GESTR analysis results.
These conditions are:
1.
Calculation of a sufficient number of plant specific peak clad temperature (PCT) points based on both nominal input values and Appendix K values to verify the shape of the PCT curve versus break size, 2.
Confirmation that plant specific operating parameters have been bounded by the models and inputs used in the generic calculations.
3.
Confirmation that the plant specific ECCS configuration is consistent with the referenced plant class ECCS configuration.
9106280076 910619 PDR ADOCK 05000293 p
2 The licensee has reported the results of those analyses which are required to meet these conditions.
Specifically, the analyses include break sizes from 0.05 sq ft to the design basis accident (00A) recirculation suction line break (4.36 sq ft).
Eleven different break sizes were analyzed in conjunction with ECCS failure combinations.
A total of 20 cases were evaluated to establish the trend of PCT curves (nominal and Appendix K) versus break size.
The input parameters for both the nominal and Appendix K cases were selected to be conservative relative to the fuel thermal-hydraulic design and ECCS performance requirements reflected in the current Pilgrim Technical Specifica-tions.
The ECCS configuration of Pilgrim (LPCI, LPCS, HPC) and ADS) is consistent with the ECCS configuration of a generic BWR 3/4 with the exception that Pilgrim uses a loop selection logic for LPCI injection as opposed to the LPCI-modification configuration used in the generic studies.
For the battery failure, this results in two LPC) pumps injecting into one recirculation loop for Pilgrim as opposed to two LPCI pumps into two separate recirculation loops for the generic BWR 3/4 For the LPCI IV failure, the LPCI mode is disabled, and only two core spray systems remain for Pilgrim, as opposed to two core spray and two LPCI pumps available for the generic BWR 3/4. This causes the ECCS makeup flow rate for the LPCI IV failure case to be lower than that of the battery failure case.
Another difference between Pilgrim and the generic BWR 3/4 plants is that the Pilgrim vessel is smaller in size, which contributes to a shorter blowdown period. The licensee analysis predicts that the limiting failure for the Pilgrim DBA with Appendix K input assumptions is the LPCI injection valve failure (LPCI mode disabled) and the limiting single failure with nominal input assumptions is a battery failure.
These results differ from the generic results where the limiting single failure is the same for both the Appendix K case and the nominal case.
I Since the differences in the Pilgrim plant resulted in a different limiting single failure for the Appendix K case relative to the nominal case, the generic upper bound PCT is not applicable. The licensee, therefore, performed a complete set of PCT calculations (nominal, licensing basis and upper bound) using the approved method for each of the potentially limiting failures (battery failure and LPCI-IV failure) to demonstrate compliance with the ECCS acceptance criteria of 10 CFR 50.46 and Appendix K.
For both cases, the upper i
bound PCT was found to be less than 1600'F and less than the PCT computed when Appendix K input assumptions are used (licensing basis PCT). The requirements of the methodology are, therefore, satisfied.
PCT results were obtained for GE fuel type BP/P8x8R which is currently loaded in the Pilgrim core and for GE fuel type 8x8EB/NB which will be loaded in l
Pilgrim in Cycle 9.
Because the accident analyses have been performed using approved methods, and the results meet the staff's acceptance criteria, we conclude that these analyses are acceptable and the results may be used to provide a new LOCA licensing basis for PNFS.
l l
3-The average power range monitor, rod block monitor and TSs (ARTS) improvement program, as well as an extended load line limit analysis (ELLLA), have been introduced at Pilgrim. The limiting LOCA condition for Pilgrim operating in the ARTS /ELLLA region occurs at rated power and about 85 percent core flow.
The licensee calculated the licensing basis PCT and upper bound PCT for low core flow conditions and the results were found to satisfy staff requirements.
The bounding 14APLHGR limits used in the Pilgrim SAFER /GESTR-LOCA analyses (e.g., 12.5 kw/ft for BP/P8x8R fuel and 13.2 kw/ft for GE 8x8 EB/NB fuel) are higher than the expected thermal-mechanical MAPLHGR for both fuel designs.
The current MAPLHGR limits for Pilgrim remain ialid, since they are less than or equal to the bounding MAPLHGR used in the SAFER /GESTR-LOCA analysis.
The change in application methodology requires a TS modification to establish the revised basis for the safety analyses of PNPS. The proposed change is to TS 6.9.A.4.b which identifies information provided in the Core Operating Limits Report. The modification correctly identifies the documentation as NEOC-31852P (see Reference 2) and is, therefore, acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the State of Massachusetts State official was notified of the proposed issuance of the amendment. The State official had no concents.
4.0 E4VIRONMENTAL CONSIDERATION The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (56 FR 9375). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
Based on the review described above, we conclude that GE Report NEDC-31852P presents sufficient information to support its use and reference in developing reload license amendments for PNPS.
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the healta and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical t<> the common defense and security or to the health and safety of the public.
0.0 REFERENCES
1.
Letter, G. W. Davis (Boston Edison) to Document Control Desk (USNRC),
December 10, 1991.
2.
General Electric Company, " Pilgrim Nuclear Power Station SAFER /GESTR-LOCA Loss-of-Coolant Accident Analysis," NEDC-31852P, September 1990.
3.
NEDE-23785-1-PA, "The GESTR-LOCA and SAFER Models for the Evaluation of the loss-of-Coolant Accident" Volume 1, 11 and 111, General Electric Company, June 1984 4
Letter, D. J. Robare (General Electric) to R. Eaton (USNRC), May 2, 1991.
5.
Letter, G. W. Davis (Boston Edison) to Document Control Desk (USNRC),
February 6,1991.
6.
Letter, C. O. Thomas (NRC) to J. F. Quirk (GE), " Acceptance of Referencing of Licensin9 Topical Report NEDE-23785 Revision 1, Volume 111, 'The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-of-Coolant Accident,'" June 1, 1984 Principal Contributor:
M. McCoy Dated:
June 19i 1991
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