ML20197B626
| ML20197B626 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/18/1997 |
| From: | Desmond N BOSTON EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BECO-2.97.118, NUDOCS 9712240013 | |
| Download: ML20197B626 (8) | |
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g messon Esmoon 10 CFR 50.46(a)(3)(ii)
Pilgtkn Nxtear Power Staton Ho%y Hill Road i
Plymouth. Massachusetts 02360-5599 P
Nancy t.. Desmond 1
Hegulato.y RolaN a Group Manager U. S. Nuclear Regulatory Commission December,18)i1997 ATTN; Document Control Desk BECo Ltr. 2.97.118 Washington, DC 20555 Docket No. 50 293 M9fDse No. DPR 35 SubjectL Pilgrim 10 CFR 50.46(a)(3)(ii) Report for 1997 Boston Edison Company (BEco) submits this letter in accordance with 10 CFR 50.46(a)(3)(li) which requires the reporting of changes or errors in emergency core cooling system (ECCS) r ana'yses. For 1997 to-date, there have been no ret orted changes or errors in the maximum limiting peak clad temperature (PCT) for Pilgrim ECCS analyses conducted by General Elet'ric Company (GF.), the fuel vendor and supplier of LOCA analyses services.
This is the first annual report submitted by Pilgrim as required by 10 CFR 50.46(a)(3)(!!).
Prior to 1997, and since October 17,1088. tho effective date of the revision to the regulation, GE compiled all changes and errors in the i.gproved ECCS evaluation models, as tr' quired by 10 CFR 50.46(3)(i) and (ii), and provided that informat!or(to me NRC annually. Et closure 1 includes the listing of the letters sent to the NR by G.E. Nuclear Energy. Enc,losure 2 provides a listing of pertinent reports sent by GE t Pilgrim. provides a list of correspondence provided to the NRC by GE that contain information related to the maximum PCT for Pilgrim For each letter, a brief summary of the changes or errors, if any, and the effect, if any, of the change or error on the model(s) and predicted PCT is provided. A brief summary of the Information related to Pilgrim's LOCA analyses is also provided for the GE reports to BECo in Enclosure 2.
An error for a non limiting event (loss of coolant accident (LOCA) with battery failure na single failure) was self identified that was conservatively evaluated to increase PCT by < b3' F.
-h' When 50* F is added to the PCT of this event, the sum remains les than the maximum PCT d
reported for the limiting event (LOCA with low pressure coolant huection [LPCI] injection valve failure as single failure) in the Pilgrim FSAR Section 6.5, as referenced in NEDC 31852P, April.1992. NEDC-31852P reports the results of the most recent ful!-scope LOCA analysis
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performed for Pilgrim. - The licensing basis PCT reported in NEDC 31852P is 1825 *F.
The
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g cumulative increase in the licensing basis PCT is 35'F, resulting in an estimated licensing
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basis PCT.of 1860 'F. Enclosure 3 provides the details for this conservative assessment.
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. Pilgrim Nucle:.r Power St: tion This letter contains no commitments.
Should you require further information on this issue, please contact P. M. Kahler at (508) 830 7939.
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N. L Desmond PMK/dcg/207118 Attachments: (1) General Electric Nuclear Energy Letters Sent to NRC Relative to the Reporting of Changes and Errors in ECCS Evaluation Models (2) General Electric Nuclear Energy Reports Sent to BECo Relative to the Reporting of Changes and Errors in ECCS Evaluation Models.
(3) Background on ECCS Models cc: Mr. Alan B. Wang, Project Manager Project Directorate 13 Office of Nuclear Reactor Regulation Mail Stop: OWF 14B2 1 White Flint North
!455 Rockville Pike Rockville, MD 20852 U.S. Nuclear Regulatory Commission Reglan 1 475 Aliandale Road King of Prussia, PA 19403 Genior Resident inspector Pilgrim Nuclear Power Station F
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ENCLOSURE 1 to BECo Lmr 97118 general Electrig_Nucl.ggr Enerov Leften Sent to NRC Relpt;ve to the Reportino o.]
Chanutes and Errors in ECCS Evalgation Models.
1.
G E. Nuclear Energy letter to the NRC, dated June 13,1990 (MFN 023-90); subject Reporting of Changes and Errors in ECCS Evaluation Models.
The letter covered the period from October 17,1988, to June 13,1990. While this letter pre dates the original version of NEDC 31852P by three months, analyses for Pilgrim began earlier in 1988. The letter iden'ified three changes effecting jet pump plants which could increase or decrease PCT over a range of +20/100 'F.
No specific effect within this range was identified as applying to Pilgrim, 2.
G.E. Nuclear Energy letter to the NRC, dated March 12,1991 (MFN 025-91); subject:
Reporting of Changes and Errors in ECCS Evaluation Models.
The letter covered the period from June 13, 1990, to.' arch 12, 1991. The letter identified no changes or errors in the methodology described in NEDE 237851 P A, "The GESTR LOCA and SAFER Models for Evaluation of Loss-of Coolant Accidents,"
on which the Pilgrim evaluation is modeled.
3.
G.E. Nuclear Energy letter to the NRC, dated June 26,1992 (MFN 058 92); subject:
Reporting of Changes and Errors in ECCS Evaluation Models.
The letter covered the period from March 12, 1991, to June 26, 1992. The letter identified no changes or er or. in the methodology described in NEDE 23785-1 P-A on which the Pilgrim ovaluation is modeled.
General Electric also reports that a change of input procedures in conjunction with a change in the G.E. computer operating system for SAFER /GESTR resulted in PCT changes less than +/ 50 'F. Pilgrim's analyses, except for reload fuel heatup ant'yses, pre dates the change in G.E.'s computer operating system. Fuel heatup analysis sets MAPLHGR limits for reload fuel that do not result in a higher PCT than previously reported for earlier fuels evaluated. Therefore, the change in PCT due to the change n GE's computer operating system and input procedures has no effect on Pilgrim's reported PCT. However, it is unlikely that the former computer operating system used for Pilgrim's LOCA analyses was retained at General Electric Company, and the revised procedural changes for input are linked to the new GE computer operating system.
Hence, any future Pilgrim specific LOCA analysis on the new GE computer operating system would be affected by this change.
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GE Nuclear Energy letter to the NRC, dated June 30,1993 (MFN 090 93); subject:
i Reporting of Changes and Errors in RCCS Evaluation Models.
Th& letter covered the period from June 26, 1992, to June 30, 1993. Tha letter i
identified two minor coding errors in the methodology described in NEDE 237851 P A on which the Pilgrim evaluation is modeled. The errors were corrected. The impact of the errors on predicted PCT was +/ 5 degrees Fahrenheit. GE also provided additional information on the impact upon PCT of the earlier reported sensitivity to changes of
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input procedures in conjunction with a change in GE's computer operating system. The range of Imoset has increased 85 'F with one case of 102 *F. While the letter does not specify any sign i for the increase in range, it can be asmed to be a positive increase l
In PCT. GE has not re-run Pilgrim's analysis using the new hardware.
I 5.
G.E. Nuclear Enelgy letter to the NRC, dated July 1,1994 (MFN 008 94); subject:
Reporting of Changes and Errors in ECCS Evaluation Models.
Tlie letter covered the period from June 30,1993, to July 1,1994. The letter identified no changes or errors in the methodology described in NEDE 237851 P A on which the Pilgrim evaluation is modeled.
6.
G,E. Nuclear Energy letter to the NRC, dated June 24,1995 (MFN 087 95); subject:
Reporting of Changes and Errors in ECCS Evaluation Models.
The letter covered the period from July 1,1994, to June 24,1995. The letter identified no changes or errors in the methodo'ogy described in NEDE 237851 P A on which the Pilgrim evaluation is mode!ed.
7.
G.E. Nuclear Energy letter to the NRC, dated December 15,1995 (MFN 278 95);
subject: Reporting of Changes and Errors in ECCS Evaluation Models.
The letter covered the period from July 1,1994, to December 15, 1995. The letter identified no changes or errors in the methodology described in NEDE 237851 P A on which the Pilgrim evaluation is modeled.
The December 15,1995 letter contained preliminary Information that was revised in a ue Nuclear Energy letter to the NRC, dated February 20,1996 (MFN 020-96); subject:
Reporting of Changes and Errors in ECCS Evaluation Models. The February 20,1996 letter identified an additional blowdown path from the reactor vessel to the drywell when a break is postulated in a recirculation pipe line. This path is the bottom head drain line to the reactor water cleanup system (RWCU) and return to the broken recirculation line.
Pilgrim does have a bottom head drain line, but RWCU return is to the feedwater line.
A recirculation line break at Pilgrim would not be augmented in blowing down the vessel by this flow path which leads back to the vessel until isolated. A feedwater line break may be affected by the bottom head drain line flow path, but this is not expected to increase PCT for this non limiting event.
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G.E. Nuclear Energy letter to the NRC, dated June 28,1996 (MFN 088 96); subject:
Reporting of Changes and Errors in ECCS Evaluation Models.
j The letter covered the pedod from December 15,1995, to June 28,1996. There were which the Pilgrim evaluation is modeled.
GE rpecifically reported to BECo in a-
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no changes or errors in the SAFER /GESTR model described in NEDE 23785-1 P A on separate letter of May 29,1996, that the error reported for unspecified utilities having fuel with large water rods did NOT impact Pilgrim.
9.
G.E. Nuclear Energy letter to the NRC, dated June 27, 1997; subject: Reporting of i
Changes and Errors in ECCS Evaluation Models.
l The letter covered the period from June 28,1996, to June 27,1997. There were no changas or errors identified in the SAFER /GESTR model described in NEDE 237851 P A '~ a41lch the Pilgrim evaluation is modeled. GE reported a known conservatism i.,
Nnsity that would decrease PCT by 25 *F.
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i Pilgrim Nucle:r Power Station ENCLOSURE 2 to BECo Lctt:r 97118 General E'ectric Nuclear Entfav Reports Sent to BECo Relative to the Reportino of Channes and Errors in ECCS Evaluation Mode.h.
1.
G.E. Nuclear Energy report to BECo,. NEDC 32306P,
- Maximum Extended Load Line Limit (MELLL) Analyses for Pilgrim Nuclear Power Station Reload 9 Cycle 10,* published March 1994.
l This report estimates less than a 10 'F Increase in PCT for initial operation at the lowest core flow rate allowed at 100% rated power for MELLL, i.e.,75% of rated core flow. However, this i
increase presumes equal initial fuel bundle power at 87% (previously evaluated in NEDC-31852P) and 75% (reevaluated in NEDC 32306P)) rated enre flow. Maximum fuel bundle power at 75% rated core flow would be less than at 87% rated core flow besed upon MCPR operating limit requirements in reference 2 listed below, This reduction in initial fuel bundle power would l
decrease PCT, more than offsetting the increase due to early boiling transition, the phenomenon related to lower initial core flow rate.
2.
G.E. Nuclear Energy report to BECo, NEDO 31312P, " ARTS Improvement Program Analy41s for Pilgrim Nuclear Power Station," published September 1987.
This report prescribes fuel operating limits which, in cor junction with fuel specific MAPLHGR limit curves, maintains expected PCT for the postulated LOCA equal to or less than that reported in NEDC 31852P, Revision 1. These limits are updated each cycle in the Pilgrim Core Operating Limits Report (COLR) as a supplement to Technical Specifications.
3.
G.E. Nuclear Energy Supplemental Reload Licensing Reports. These roports confirm to BECo that the calculated PCTs of subsequent reload fuel designs, operating under the constraints of NEDO 31312P and within fuel specific MAPLHGR limit curves, are less than that reported in NEDC 31852P, Revision 1.
Supplemental reports received after the original version of the LOCA analysis report and incorporated into the COLR are listed below:
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- Reload 8/ Cycle 9 Supplemental Reload Licensing Report." GE Report 23A7101, March e
1991
" Reload 9/ Cycle 10 Supplemental Reload Licensing Report," GE Report 23A7195, March e
1993
- Reload 10/ Cycle 11 Supplemental Reload Licensing Report," GE Report 24A5172, February 1995
' Reload 11/ Cycle 12 Supplemental Reload Licensing Report," GE Report J1103014SRL, e
- Rev 0, March 1997 i
4.
G.E. Nuclear Energy Report GE NE B1100617 03, Revision 4, " Safety Evaluation of Installation of Stabilizers on the Pilgrim Nuclear Power Station Core Shroud," 1994.
Section 1.4A.of this report assessed an increase of PCT for the limiting LOCA event to be less than 10 'F for the effects of the core shroud repair implemented at Pilgrim in 1995 during RFO-10.
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. Pilgrim Nuclear Power Station ENCLOSURE 3 to BECo Letter 97118 Backaround on ECCS Modell Spmmary This enclosure provides a background regarding the ECCS models by which the Pilgrim LOCA evaluations were performed Revision 1 to NEDC 31852P referenced in the Pilgrim FSAR Section 6.5.6 is the most recent report of the latest full-scope LOCA analysis of record specific to Pilgrim.
This 1992 revision of the original 1990 report contained only administrative corrections to the 1990 report's results. Thus, the models used reflect those used by General Electric Company in the late 1989 to early 1990 period.
This enclosure summarizes the effects of all changes and errors on the licensing basis PCT last reported in
- Pilgrim Nuclear Power Station ' /ER/GESTR LOCA Loss of Coolant Accident Analysis", NEDC-3.J52P, Revision 1, April 1992 (Reference 17, Section 6.5.6, Pilgrim UFSAR).
Dp_qkaruund of the ECC1 Evaluation Models for Pilarim.
Before 1990, the ECCS evaluation model on which the Pilgrim evaluation was v odeled consisted of the models described in General Electric Nuclear Energy document NEDE 20566 P A, " Analytical Model for Loss of Coolant Analysis in Accordance with 10 CFR 50, Appendix K," January 1976, and NEDO 30767,
- Pilgrim Nuclear Power Station Loss of-Coolant Accident (LOCA) Analysis Update," September 1984. The evaluation models for the Pilgnm sva'iiation were changed from NEDE 20566 P A to the models described in General Electric Nealear Energy document NEDE 237851 P A, *The GESTR LOCA and SAFER Models for Evaluation of Loss of Coolant Accidents", February 1985. The change was made in 1990 to support MAPLHGR limits for fuel scheduled for cycle 9 operation. The licensing basis (Appendix K) PCT with all adders was 1825 *F for the limiting fuel type.
S_ummary of effects on PCT reportedjor Pilarim in NEDC-31852R Revision 1.
The maximum limiting PCT reported in NEDC 31852P and referenced in the Pilgrim FSAR section 6.5.0, was 1825 *F for the 4.36 square foot break of the recirculation suction line coincident with loss of offsite power and a failure of the LPCIinjection valve.
Two of the three changes reported in Enclosure 2, item 1, may apply to Pilgrim's liniiting event with a maximum increase of 20 'F in PCT assumed for Pilgrim though a decrease in PCT by a maximum of 100 'F is as likely based upon the information provided. One of the two errors reported in Enclosure 1, item 4, above may apply to Pilgrim's limiting event and a 5
- F increase in PCT is conservatively assumed to apply, again neglecting the possibility that the PCT may de:rease by 5 'F, Finally, Enclosure 2, item 4, adds 10 'F to the limiting PCT and is the only reported change that specifically applies to the Pilgrim limiting event and clearly results in an increase in PCT. The maximum possible cumulative PCT is, therefore, 1860 'F (1825 + 20 + 5 + 10 'F).
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., items 2 and 5 9 and Enclosure 2, items 13 either included no changes or no errors relative to the models and methodology used to evaluate PCT for Pilgrim; or involved changes or errors that do not specifically apply to Pilgrim; or involved changes that are expected to result in a decrease in PCT. Pilgrim takes no credit for expected conservatisms until specifically incorporated into a full-scope LOCA analysis with specific assumptions and inputs applicable to Pilgrim.
The reported changes in Enclosures 1 and 2, have been reviewed. The review concludes that no combination impacts non limiting LOCA events more than that conservatively estimated above for the limiting LOCA event.
A self identified error results in an additional delay of less than 5 seconds to supply power to the LPCI injection and recirculation pump discharge valves' motors when aligned to an emergency swing bus that is initially aligned to a diesel generator that is subsequently
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assumed to be unavailable. This conservatively added < S0 *F PCT to this non limiting event, reported in NED>31852P as 1694
'F.
The sum of (1694 + 35 + S0) = 1779 'F remains below the maximum licensing basis PCT of 1825'F reported in NEDC 31852P, Revision 1 as referenced in Pilgrim FSAR, section 0.5.6.
The effects on Pilgrim PCT of input procedural changes in c)njunction with computer operating system changes as reported in Enclosure 1, Iteni. 3 and 4 have not been determined in a Pilgrim-specific LOCA analysis The last full scope, Pilgrim specific LOCA analyses were evaluated before these procedure changes were implemented at GE, It is more likely the effects of Enclosure 2, items 1 and 4, and Enclosure 2, item 4 on calculated PCT would result in a net decrease or a slight net increase rather than the worst case sum of individual increases if evaluated in a full scope, plant specific LOCA enalysis in early 1991 (before GE computer system changed) under the same procedures and operating systems used in 1989-90.
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