ML20198C920
| ML20198C920 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/17/1998 |
| From: | Alexander J BOSTON EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BECO-2.98.157, NUDOCS 9812220213 | |
| Download: ML20198C920 (10) | |
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O Boseers smoore 10 CFR 50.46(a)(3)(ii)
Pilgrim Nuclear Power Station Rocky Hill Road Plymouth, Massachusetts 02360-5599 U. S.~ Nuclear Regulatory Commission December 17,1998 ATTN: Document Control Desk-BECo Ltr. 2.98.157 Washington, DC 20555 Docket No. 50-293 License No. DFR-35
Subject:
Pilgrim 10 CFR 50.48(a)(3)(ii) Report for 1998 Boston Edison Company (BECo) submits this letter in accordance with 10 CFR 50.46(a)(3)(ii)
' which requires the reporting of changes or errors in emergency core cooling system (ECCS) analyses. For 1998 to-date, there have been no reported changes or errors in the maximum limiting peak clad _ temperature (PCT) for Pilgrim ECCS analyses conducted by General Electric Company (GE), the fuel vendor and supplier of LOCA analyses services.
This is the second annual report submitted by Pilgrim as required by 10 CFR 50.46(a)(3)(ii).
The first annual report for 1997 was provided in a letter report to your office dated December
.18,1997. Prior to 1997, and since October 17,1988, the effective date of the revision to the regulation, GE compiled all changes and errors in the approved ECCS evaluation models, as required by 10 CFR 50.46(3)(i) and (ii), and provided that information to the NRC annually. includes the listing of the letters sent to the NRC by G.E. Nuclear Energy, provides a listing of pertinent reports sent by GE and BECo to the NRC. The list hcludes our December 18,1997 report.
. Enclosure 1 provides a list of correspondence provided to the NRC by GE and the most recent GE correspondence provided to BECo 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. Two LER reports are pertinent to the current reporting period but were provided earlier in 1998 to the NRC in accordance with 30 day reporting requirements under 10CFR50.46 and 10CFR50.73. These LER's are listed in Enclosure 2.
An error for a non-limiting event (loss of coolant accident [LOCA) with battery failure as single
,4 failure) was self-identified. It was conservatively evaluated to increase PCT by <'70 F.
When 70* F is added to the PCT of this event, the sum remains less than the maximum PCT reported for the limiting event (LOCA with low pressure coolant injection [LPCl] injection valve failure as single failure) in the Pilgrim FSAR Section 6.5, as referenced in NEDC-31852P, h
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Rev.1, April 1992. NEDC-31852P reports the results of the most recent full-scope LOCA analysis performed for Pilgrim. The licensing basis PCT reported in NEDC-31852P is 1825
' F.
Except as reported in reference 7 (LER 98-015-00) of Enclosure 2, the cumulative inaease in the licensing basis PCT is 45 F, resulting in an estimated licensing basis PCT of 1870 F. Enclosure 3 provides the details for this conservative assessment. The increase of 10 *F from our 1997 report is due to a correction of information provided in 1997 and reevaluated in 1998 for the effect of item 7 in Enclosure 2 on Pilgrim's ECCS results.
Wherever appropriate, these enclosures include new information beyond that provided in their equiva!ent provided in the 1997 report.
The predominant fuel to be used in Pilgrim cycle 13 (scheduled to begin in 1999) is a 9X9 design, calculated to have the effect of decreasing Pilgrim PCT by 10 'F. This benefit is not l
credited in any computations supporting this report and the adjustments of any PCT value(s).
This letter contains no commitments.
Should you require additional information on this issue, please contact P. M. Kahler at (508) 830-7939.
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lexander clear Assessment Group Manager PMK/bjt 298157 l
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(1) General Electric Nuclear Energy Letters Sent to NRC Relative to the Attachments:
Reporting of Changes and Errors in ECCS Evaluation Models (2) General Electric Nuclear Energy Reports Sent to BECo Relative to the 1
l Reporting of Changes and Errors in ECCS Evaluation Models.
1 (3) Background on ECCS Models l
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' Mr. Alan B. Wang, Project Manager cc:
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. Project Directorate 1 Office of Nuclear Reactor Regulation Mail Stop: OWF 14B2' 1 White Flint North 11555 Rockville Pike Rockville, MD 20852 l
U.S. Nuclear Regulatory Commission
- Region 1 475 Allendale Road King of Prussia, PA 19406 Senior Resident inspector Pilgrim Nuclear Power Station I
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ENCLOSURE 1 to BECo Letter 2.98.157 General Electric Nuclear Enerav Letters Sent to NRC Relative to the Reportino of Chances 3nd Errors in ECCS Evaluation 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 identified 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 March 12, 1991. The letter identified no changes or errors in the methodology described in NEDE 23785-1-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 errors in the methodology described in NEDE 23785-1-P-A on which the Pilgrim evaluation is modeled.
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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 analyses, pre-dates the change in GE'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,in 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 i
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 l
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:
Reporting of Changes and Errors in ECCS Evaluation Models.
l The letter covered the period from June 26, 1992, to June 30, 1993. The letter identified two minor coding errors in the methodology described in NEDE 23785-1-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 input procedures in conjunction with a change in GE's computer operating system. The l
range of impact has increased 85 F with one case of 102 F. While the letter does not i
specify any sign i for the increase in range, it can be assumed to be a positive increase in PCT. GE has not reported re-running Pilgrim's analysis using the new hardware.
5.
G.E. Nuclear Energy letter to the NRC, dated July 1,1994 (MFN 088-94); subject:
Reporting of Changes and Errors in ECCS Evaluation Models.
The 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 23785-1-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.
l The letter covered the period from July 1,1994, to June 24,1995. The letter identified no changes or errors in the methodology described in NEDE 23785-1-P-A on which the Pilgrim evaluation is modeled.
7.
G.E. Nuclear Energy letter to the NRC, dated December 15,1995 (MFN 278-95);
l subject: Reporting of Changes and Errors in ECCS Evaluation Models.
l The letter covered the per;od from July 1,1994, to December 15, 1995. The letter identified no changes or errors in the methodology described in NEDE 23785-1-P-A on which the Pilgrim evaluation is modeled.
l The December 15,1995, letter contained preliminary information that was revised in a GE 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 postulating a recirculation line break. This path is the bottom head drain line to the j
reactor water cleanup system (RWCU) and return to the broken recirculation !ine.
Pilgrim does have a bottom head drain line that may result in a very small additional blowdown path from the reactor vessel. This flow pathway is also restricted by substantial long piping lengths, small piping cross sections, and other high flow l
resistance factors, significantly limiting the break flow rate. This was reported to be an l
increase of PCT of less than 10 F.
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G.E. Nuclear Energy letter to the NRC, dated June 28,1996 (MFN 088-96); subject:
i Reporting of Changes and Errors in ECCS Evaluation Models.
The letter covered the period from December 15,1995, to June 28,1996. There were no changes or errors in the SAFER /GESTR model described in NEDE 23785-1-P-A on which the Pilgrim evaluation is modeled.
GE specifically reported to BECo in a separate letter of May 29,1996, that the error reported for unspecified utilities having j
fuel with large wc%r rods did NOT impact Pilgrim.
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G.E. Nuclear Energy letter to the NRC, dated June 27, 1997; subject: Reporting of Changes and Errors in ECCS Evaluation Models.
The letter covered the period from June 28,1996, to June 27,1997. There were no l
changes or errors identified in the SAFER /GESTR model described in NEDE 23785 l-P-A on which the Pilgrim evaluation is modeled. GE reported a known conservatism in fuel density that would decrease PCT by 25 'F.
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G.E. Nuclear Energy letter to BECo, dated July 20,1998; subject: Annual Report of Changes and Errors in ECCS Evaluation Models.
t The letter covered the period from June 27,1997, to June 30,1998. It includes as an 1
attachment a related GE (G.A. Watford) letter to T.E. Collins of the NRC, dated June 30,1998. This report identified no change or error in ECCS evaluation models for the period.
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ENCLOSURE 2 to BECo Lett::r 2.98.157 General Electric Nuclear Enerav Reports Sent to BECo. and BECo Correspondence Sent to NRC. Relative to the Reportina of Chanaes and Errors in ECCS Evaluation Models.
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 increase presumes equal initial fuel bundle power at 87% (previously evaluated in NEDC-31852P) and 75% (reevaluated in NEDC-32306P)) rated core flow.
Maximum fuel bundle power at 75% rated core flow would be less than at 87% rated core flow based upon MCPR operating limit requirements in reference 2 listed below.
This reduction in initial fuel bundle power would 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 Analysis for Pilgrim Nuclear Power Station," published September 1987.
This report prescribes fuel operating limits which, in conjunction 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 reports confirm to BECo that the calculated PCTs of subsequent reload fuel designs, operating under l
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:
" Reload 8/ Cycle 9 Supplemental Reload Licensing Report," GE Report 23A7101, March 1991
" Reload 9/ Cycle 10 Supplemental Reload Licensing Report," GE Report 23A7195, March 1993
" Reload 10/ Cycle 11 Supplemental Reload Licensing Report," GE Report l
24A5172, February 1995
" Reload 11/ Cycle 12 Supplemental Reload Licensing Report," GE Report J11-l 03014SRL, Rev 0, March 1997 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.
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r Section 1.4.4 of this r: port asssssed an incrossa of PCT for tha limiting LOCA ovant to be less than 10 'F for the effects of the core shroud repair implemented at Pilgrim in 1995 during RFO-10.
5.
BECo letter to the NRC, dated December 18,1997, (BECo Ltr. 2.97.118); subject:-
Pilgrim 10 CFR 50.46(a)(3)(ii) Report for 1997.
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BECo letter to the NRC, dated July 22,1998, (BECo Ltr. 2.98.096); subject; LER 98-
. 014-00 " Degraded Voltage Restoration Time Not Consistent with FSAR."
7.
BECo letter to the NRC, dated July 22,1998, (BECo Lt. 2.98.097); subject; LER 98-015-00 "Non-Conservative Degraded Voltage Setpoint."
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s ENCLOSURE 3 to BECo Letter 2.98.157 3
Backaround on ECCS Models y
Summary 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 L
FSAR Section 6.5.6 is the most recent report of the latest full-scope LOCA analysis of record i
l 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.
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-This enclosure summarizes the effects of all changes and errors on the licensing basis PCT l
last reported in Pilgrim Nuclear Power Station SAFER /GESTR-LOCA Loss-of-Coolant Accident Analysis," NEDC-31852P, Revision 1, April 1992 (Reference 17, Section 6.5.6, Pilgrim UFSAR).
Backaround of the ECCS Evaluation Models for Pilarim.
Before 1990, the ECCS evaluation model on which the Pilgrim evaluation was modeled j
consisted of the models described in General Electric Nuclear Energy document NEDE l
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 Pilgrim evaluation were changed from NEDE 20566-P-A to the models described in General Electric Nuclear Energy. document NEDE 23785-1-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 i
basis (Appendix K) PCT with all adders was 1825_*F for the limiting fuel type.
Summary of effects on PCT reported for Pilarim in NEDC-31852P. Revision 1.
The maximum limiting PCT reported in NEDC-31852P and referenced in the Pilgrim FSAR l
section 6.5.6, 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 LPCI injection valve.
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Two of the three changes reported in Enclosure 2, Item 1, may apply to Pilgrim's limiting 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 l
F increase in PCT is conservatively assumed to apply, again neglecting the possibility that the PCT may decrease by 5 F. A!so, 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. Finally, Enclosure 2, item 7, adds 10 *F to the limiting i-PCT. The maximum possible cumulative PCT is, therefore,1870 F (1825 + 20 + 5 + 10 +
L' 10 F ).
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', items 2 and 5-9 and Enclosure 2, items 1-3 either included no changes or no errors relative to the models and methodology used to evaluate PCT for Pilgrim; or involved l
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.
L A self-identified error produces an additional delay of less than 7 seconds to supply power to l
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 assumed to be unavailable. This conservatively added < 70 F PCT to this non-limiting event, reported in NEDC-31852P as 1694 F. The sum of (1694 + 45 + 70) = 1809 F remains below the maximum Appendix K licensing basis PCT of 1821 F reported in NEDC-31852P, Revision 1 as referenced in Pilgrim FSAR, section 6.5.6.
The effects on Pilgrim PCT of input procedural changes in conjunct;on with computer operating system changes as reported in Enclosure 1, items 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 L
PCT would result in a net decrease or a slight net increase rather than the worst case sum of l-
~ individual increases if evaluated in a full-scope, plant-specific LOCA analysis in early 1991 l
(before GE computer system changed) under the same procedures and operating systems l
used in 1989-90.
An audit of GE LOCA/ECCS calculations in 1998 reinforced this expectation.- While evaluating the effect of 9X9 fuel on Pilgrim's PCT results, several l
computer runs for 8X8 fuel were re-executed in the 1993-4 DRF to verify consistency with 1
l 1990 results before model modifications were made for the fuel change. Later PCT results l'.
. (on the new machine) were within only a few degrees of the earlier results, and no trend of either increase or decrease in PCT could be determined.
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