ML20079L065
| ML20079L065 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 10/24/1991 |
| From: | Donnelly P CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Martin T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 9111060005 | |
| Download: ML20079L065 (6) | |
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POWERING cl _4 tutICNiluAN'S PROGRES5 fg' Pabsades Nucteer Plant 27780 Blue Star Memonal H>ghway, Covert. MI 49043 October 24, 1991 Thomas 0 Martin US Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 PALISADES PLANT - RESULTS OF REVISED RTEAM GENERATOR MAIN STEAM LINE N0ZZLE LOAL CALCULATIONS As a result of your request and our recent discussions, attached are the results of the revised steam generator main steam line nozzle load calculations. We are providing the results as a comparison to the original margins to the piping stress allowables, that were calculated prior to incorporating the comments provided as a result of the Special Engineering Inspection (91-202).
I've included a short discussion to explain the table and how the results were achieved, and a chronolog, 7f events leading up to our responding to your request.
Should you desire further information or like to review the specific calculation please feel free to contact me.
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Patrick M Donnelly Palisades Plant Safety and Licensing Director PMD 91*016
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g PALISADES PLANT M11LSHAtLOlliLET N0ZZLE MARGIN *COMPARIS0NS PRE 91-202 POST 91-202 STRESS TYPE tBRGINS MARG iflS_._
PRIMARY MEMBRANE 0.51 0.21 PRIMARY MEMBRANE &
59.3 57.6 BENDING PRIMARY AND SECONDARY 30.8 22.8 FATIGUE USAGE-FACTOR 98.0 97.6 MAX FAULTED STRESS, SSE 20.3 19.3
- Margin Equals o Allos ble - o Calc x 100%
o Allowable o Calc is maximum value for either SG i
DISWS110B 0F TABLE As a result of replacement of steam generators Bechtel Power Corporation (BPC), calculated new nozzle loads for main steam outlet nozzles.
Due to contractual limitations, only the NSSS supplier (CE) has the capability to determine the ultimate acceptability of nozzle loading versus ASME Code allowables.
Thus, the loads supplied by BPC were submitted to CE by Consumers Power Company (CPCo) for review and analysis.
After review and analysis, CE supplied information indicating all nozzle loads were below ASME Code allowables and therefore were acceptable (3/8/91).
The
" Pre 91-202 Margins" column in the attached table thus represents the calculated state of the main steam nozzles prior to the June 1991 NRR inspection (which included review of the BPC calculations on which the CE nozzle load acceptance was based).
The NRR Special Engineering Inspection (91-202) raised the questions regarding some of the methods and assumptions used in BPC's calculitions related to main steam line piping analysis, CPCo requested that BPC revise the affected calculations based on the inspection comments.
This revision altered some of the earlier results and required CPCo to resubmit the nozzle loads to CE for
-reanalysis. CE's response indic.ted that the nozzles continued to meet ASME Code, but that loads had increased somewhat (reducing earlier calculated margins).
The " Post 91-202 Margins" column in the table presents the current state of the main steam nozzles..
In parallel with the actions described above, CPCo contracted with Sargent-Lundy (S&L) to provide an indcpenoent technical review of revised calculations supplied by BPC in response to the NRR inspection and to review other BPC responses that did not result in calculation revisions.
This review and
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' comment resolution is sufficiently completed, as of October 14, 1991, to l-conclude that S&L comments on the BPC calculation's chat form the basis for CE's acceptance of nozzle loads, will not chan9e the results; ie, main steam r
nozzlo loads centinue to be acceptable, as determined by CE.
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4 MAIN STEM N0ZZLE LOADS QiBDNOLOGY 0F CALCVLATIONS 2/91 Original revised steam generator nozzle loads (BPC calculation) transmitted to CE in 2/91.
3/8/91 Original CE response stating that nozzle loads were acceptable dated 3/8/91 (received officially 3/20/91).
6/10-21/91 PRC Team Inspection identified concern with certain aspects of calculations related to main steam.
BPC committed to specific actions which included a recalculation to address those concerns.
8/2/91 BPC completed reanalysis and internal reviews, and submitted-revised nozzle loads to CPCo on 8/2/91.
(Based only on exit and inspection discussions).
P/5/91 NRC Special Engineering inspection reports received 8/5/91 provided_ details of concerns..CPCo verbally requested BPC to review 8/2/91 report and verify that planned actions (most already taken) would address NRC concerns as described in report.
8/5/91
-CPCo submitted new nozzle loads to CE for analysis (officially acknowledged on 8/11/91). CE scope included developing new nozzle loads and updating stress report.
.i 8[27/91-CE supplies new nozzle loads and deterpunation of acceptability thereof to CPCo.
8/28/91 CPCo established S&L as independent technical agent to review all BPC responses and calculation revisions done to respond to 8/2/91 NRR inspection report.
9/12/91-S&L begins review of revised calculations.
9/20/91 BPC provides written responses to all 8/2/91 inspection report items to CPCo. Copy supplied to S&L for review.
10/1 & 10/11/91 S&L supplies advance copies of comments on calculations and other material to CPCo.
10/7/91-BPC provides response to S&L 10/1/91 advance comments (nnt related to main steam line).
10/24/91 CPCo has regt. sted BPC response to other S&L comments, but not all have been resolved as of 10/14/91.
Some of these relate to main steam calculations, but, it is expected, will not affect the numerical results.
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It was necessary to determine that S&L con >ments on main steam calculations would not cause changes to loads supplied to CE, prior to considering results to be valid for submittal to NRC.
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