ML20086S863
| ML20086S863 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 12/19/1991 |
| From: | Zach J WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-91-153 IEB-88-011, IEB-88-11, TAC-M72155, TAC-M72156, VPNPD-91-452, NUDOCS 9201060036 | |
| Download: ML20086S863 (3) | |
Text
'
/
^
' Wisconsin Electnc POWER COMPANY
- m w Menon ro h3 20e Ma.oaee w n201 pj 22ms L VPNPD 452 NRC 15 3 December 19, 1991 Document Control Desk U.S. NUCLEAR REGULATORY COMMISSION Mail Station-P1-137 l Washington, D.C. 20555 Gentlemen:
DOCKET 50-266 AND 50-301 PROGRAM STATUS UPDATE 'ND EXTENSION REOUEST FOR COMPLETION _OF ACTION ITEM 3.d OF
-HBC IE BULLETIN 88-11 (TACF#72155 ANDM72156)
POINT BEACH NUCLEAR PLANT. UNITS'1 AND 2
References:
- 1) Wisconsin Electric Power Company Letter VPN?D-89-314,. dated 05/31/89, to the NRC on the subject of " Submittal of Justification for l Continued Operation Regarding Pressurizer
! Thermal Stratification, Point Beach Nuclear l Plant Units, 1 and 2."
- 2) Letter from the NRC to C. W. Fay, dated 09/25/90, on the subject of "NRC Bulletin No. 88-11, Pressurizer Surge Line Thermal Stratification - Evaluation of WOG Bounding Analysis .(Tack 72155 h andfa72156) . "
- 3) Wisconsin Electric Power Company Letter No. VPNPD-90-498, dated 12/18/90, to the NRC on i the subject of " Request for Extension of p Analysis Completion Date per Item 1.d of NRC l IE Bulletin 88-11."
- 4) Wisconsin Electric Power Company Letter No. VPNPD-91-184, dated 06/07/91, to the NRC on the subject of_" Plant Specific Thermal Stratification Analysis Results and Completion Date Extension _ Request'for Completion of Action Item'1.d of NRC'IE Bulletin 88-11."
30ill(LS i 9201060036 911219 ff l
-PDR ADOCK 05000266 0 g FDR l- Isusumm ofI&vauk thew 0m'ativs
. Document Control Desk December 18, 1991
,Page 2 In a letter dated June 7, 1991, Wisconsin Electric Power Company (WE) notified the NRC that we would not meet the completion date specified for all of the reporting reqairements in Action Item 1.d of IE Bulletin 88-11 for Point Beach Nuclear Plant (PBNP) Units
-lend 2 (Reference 4). The letter documented that WE had completed
, the plant-specific analyses for both units at PBNP. We also provided a summary ot the analysis results anu included a revised completion schedule for the limited number of items remaining to fulfill the reporting requirements of the bulletin.
Reference 4 also documented that the plant-specific design and thermal stratification analysis results demonstrated pipe stress and fatj gue code compliance for the 40-year design life of the pressurizer surge line for both units, with the exception of the Integral Welded Attachment (IWA) lug / collar design for PBNP Unit 1 pipe whip restraints. The Cumulative Usage Factor (CUF) for the Unit 1 IWAs demonstrated an additional 37 heatup and cooldown (H/C) scluences before the CUF exceeds 1.0, Reference 4 concluded by asking for an extension to December 31, 1991, for completion of all the reporting requirements for Action L
Item 1.d of the bulletin to allow sufficient time to 1) perform a system delta-T records search of our past operating plant history for H/C cycles, 2) to perform a refined IWA evaluation on the Unit.1 whip restraint design, and 3) to revise our operating r
procedures to assure compliance with the 23'*F system delta-T limit assumed in the plant specific analyses for water solid plants during heatup and cooldown.
A records search of our past operating history for H/C cycles search has now been completed by Westinghouse. The results reveal that there have been occurrences during the operating history in which tne plant exceedt.d the 210*F system delta-T limit assumed in the analyses (30 times on Unit 1 and 26 times on Unit 2). Some of the occurrences have been of higher magnitude (e.g. one system delta-T of 320*F was recorded.during heatup on Unit 2 in May of
- 1976). However, the majority are in the 250*F range.
l This unanticipated information has been transmitted to Sargent and Lundyffor an assessment of the impact these occurrences will have on the plant specific analyses they completed for PBNP earlier this year. S&L is currently evaluating what the effect of the worst case system delta-T of 320*F on Unit 2 will be, and have committed to completing this evaluation by mid-January 1992. Tnis will include an estimate of the resulting impact on code compliance for pipe stress and fatigue to WE.
Based on the these results, WE will ther determine whether the existing analyses (with the inclusion of all of the occurrences above the 210*F limit) will be able to demonstrate-code compliance, or whether we will need to initiate now analyses. Once we have
~
o' Document Control Desk Decer.ber 19, 1991
.'Page 3 nade this determination, we will notify the NRC of the results of our evaluation and provide a new schedule, if required, for completing the reporting regiairements of the bulletin.
WE has delayed-evaluation of the IWa's and revision of the plant operating procedures (to limit system delta-T's to 210*F) until the assessment by Sargent and Lundy determines whether the existing plant cpecific analyses already completed for PBNP. remain applicable. However, plant operations personnel have been made aware of the thermal stratification issue during heatup and cooldown of the plant. We are currently ave:r.ating a lower temperature limit for incorporation into our operating proceduros.
WE has concluded that PBNP can safely continue to operate at full power under the JC3 submitted to the NRC in May 1989 (Reference 1).
The basis for thiu JCO was the generic bounding analysis performed under WCAP-12277. The JCO allowed for a maximum of ten additional H/C cycles from the date of submittal in May 1989. PBNP has experienced five H/C cycles on Unit 1 and three on Unit 2 since submitting the JCO. This leaves a sufficient number of cycles to maintain an adequate safety margin, ana therefere, we conclude that there are no short-term safety concerns associated with thermal stratification effects on the surge lines at PBNP. Additionally, the magnitudes of the occurrences above the assumed 210'F system delta-T limit remain below those of the steam bubble H/C methodology for which many steam bubble plants have already been shown by Westinghouse to satisfy code requirements for pipe stress and fatigue.
.We.would be pleased to discuss this with you at your convenience.
Please contact us if you have any questions concerning our proposed actions in this manner.
Very tr21y yours
. l-7 b i u i Jamps J. Zach' VicejPresident Nuclear Power Department Copies to:. NRC Regional Administrator - Region III NRC Resident Inspector Subscribed and sworn to pefore me this 4 " day of L( % fa., 1991.
L wo A w, :
Notary Public, State'hf Wisconsin My Commission expires F - 2 2 - 7j/ .
__