ML20072P117
| ML20072P117 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 07/11/1983 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 22254, MCAR-22, NUDOCS 8307180270 | |
| Download: ML20072P117 (7) | |
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Q ll Vice l>esident - l>ojects, Engineering and Construction General offices: 1945 West Pernell Road, Jackson, MI 49201 e (517) 7880453 July 11, 1983 78-05 #13 Mr J G Keppler, Regional Administrator US Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 MIDLAND NUCLEAR C0 GENERATION PLANT DOCKET NOS 50-329 AND 50-330 REACTOR BUILDING SPRAY PIPING SUPPORTS FILE 0.4.9.17 SERIAL 22254
Reference:
(1) CPCo (S 11 Howell) letter to NRC (J G Keppler), Same Subject, Serial Howe-320-79, dated December 21, 1979 (2) CPCo Serial 20713, dated February 25, 1983 This letter, as were the referenced letters, is a 50.55(e) report concerning possible deficieny in RB Spray Anchors.
. Attachment 1 provides a summary of the corrective action status with regards to this problem.
Another report, either interim or final, will be sent on or before October 21, 1983.
DC/WRB/cd
Attachment:
MCAR 22, Addendum 1. Interim Report 2 CC: Document Control Desk NRC Washington, DC RJCook, NRC Resident Inspector Midland Nuclear Plant
~OC0783-0003A-MP01 8307180270 830711 PDR ADOCK 05000329
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2 Serial 22254 78-05 #13
- CC: CBechhoefer, ASLB Panel FPCowan, ASLB. Panel-JHarbour,~ASLB Panel MMCherry, ESQ MSinclair BStamiris
-CRStephens, USNRC WDPaton, Esq, WSNRC FJKelley, Esq, Attorney General b.'. Freeman, Esq, Asst Attorney General WHMarshall GJMerritt, Esq, TNK&J 1
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1i9243 Bechtel AssocibesMrbfessional Corporation 0
SUBJECT:
MCAR 22 (Addendum issued 1/26/83)
Reactor Building Spray System INTERIM REPORT 2 DATE:
June 20, 1983 PROJECT:
Consumers Power Company Midland Plant Units 1 and 2 Bechtel Job 7220 l
l Description of Deficiency A modeling assumption was discovered in the originr1 reactor building spray system water hammer analysis, which resulted in less conservative results.
Some of the recalculated water hammer pressures are higher than those calculated in the original analysis, f
Summary of Investiaation Bechtel has recalculated the pressure time histories for the reactor building spray system header using revised modeling assumptions. The maximum differential pressures in each spray header piping branch have changed in magnitude from -30 to +2757. from the values originally calculated (see Table 1).
The pressure time histories have been converted into force time histories.
The stress analysis has been performed using the revised water hammer force-time histories as input. A review of the preliminary stress analysis results and the piping and the piping support designs indicated that the allowables are exceeded in some instances for piping and the piping support system (piping anchors, piping hangers, and done hanger attachment lugs).
Analysis of Safety Impilcation The primary safety-related functions of the reactor building spray system are to remove sensible heat and subsequent decay heat from the reactor building and to remove fission products from the reactor building atmosphere following loss-of-coolant or main-steam-line-break accidents. The piping stress analysis and associated hanger and anchor design provides assurance that the reactor building spray header will remain intact to perform these safety functions. The calculation of the water hammer forces in the reactor building spray header is one input to the stress analysis. The final disposition of MCAR 22, Reactor Building Spray Anchor Discrepancy, was based on the original reactor building spray header piping and anchor stress analysis completed in 1979. The preliminary stress analysis using the revised modeling assumptions has indicated that the stress allowables are exceeded. Therefore, the spray system's safety-related function is in question until corrective actions are completed.
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I19243
- 935, Bechtel Associates Professional Corporation NCAR 22 Interim Report 2 Page 2 Probable Cause The increased loads observed on piping and piping anchors were caused by l
simplifying modeling assumptions made in the original water hammer analysis that appeared reasonable at the time but were subsequently found to be less conservative in certain cases.
Corrective Actions The following actions have been initiated.
1.
Design Review of the Pipinz. Hanaer. and Anchor Desian Because the revised water hammer loads resulted in exceeding the allowables for the piping and piping supports, two options were considered to reduce the water hammer loads:
Model testing in conjunction with any required support system a.
modifications. The new water hammer load force time histories are believed to be very conservative. It is estimated that model testing would provide a basis for reduction of the peak water hammer forces by at least 40 percent.
b.
Redesigning the spray header piping to reduce the water hammer load force time histories in conjunction with any required pipe support system modification to bring the system to within allowable loads Both Options a and b would provide a technically acceptable resolution to the identified concern. Option b was selected because it appeared that Option a would not eliminate the need for system design modifications.
Option b also has less schedule impact because the new system reanalysis is not restrained by model testing completion, which was estimated to take several months. Key activities required to support Option b are as follows:
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- 1) Revise water hammer force time histories based on revised piping design.
- 2) Obtain as-installed key dimensions.
- 3) Revise the piping stress analysis.
- 4) Issue piping isometrics.
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I19243 I;g35, Bechtel Associates Professional Corporation NCAR 22 Interim Report 2 Page 3
- 5) Verify or modify the piping support system to bring it within i
allowables.
- 6) Issue design drawing for support system modifications.
- 7) Perform construction activities.
An engineering production schedule is being developed to coordinate these activities.
2.
Determination That the Modelina Assumptions in Ouestion Were Not Used in Other Water Hansrer Analyses on the Midland Project A susenary of the modeling assumptions and their use has been distributed to other Bechtel AA0 project and staff entities performing water he. amer analyses for assessment of applicability to their work. This review is complete. No other water hammer analyses used the modeling assumptions in question.
The basis for the probable cause involves engineering judgment and decisions and is not associated with a deficiency in engineering procedures or practices. Therefore, no process corrective action is required.
Reportability Consumers Power Company reported this condition to the NRC on January 25, 1983, under the criteria contained in 10 CFR 50.55(e).
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liS243 liS352 l
Bechtel Associates Professional Corporation NCAR 22 Interim Report 2 i
Page 4 Submitted by:
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- d. J 6[ <.y M.A. Skelley
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Nuclear Systems Group Super-visor Approved by:MK E.M. ITTghes ~
Project Engineer l
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Concurrence by:
R.B. Fallgrei l
Geotechnical Services i
Concurrence by N L
OA-d B41. Loos i
Chief Nuclear agineer Concurrence by:
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E.H. Smith j
Engineering Nanager t
f Concurrence by:
N.A. Dietrich Project Quality Assurance i
l Engineer NAS/NCP/isb*
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li9243 Bechtel Associates Professional Corporation NCAR 22 1.teria R., ort 2 ili9352 Pa8e 5 TABLE 1 REACTOR JUILDING SPRAY HEADER DIFFERENTIAL PRESSURES Reactor Building Spray Maximum Differential Header Pipe Number and Pressure (ft of water)
Percent Ouadrant Orlainal Analysis Revised Ana1Ysis Chanmod 1GCB-12, Quad 1 1,190 840
-30 1GCB-12, Quad 2 1,190 840
-30 1GCB-10, Quad 1 508 540
+6 1GCB-10, Quad 2 508 600
+18 1GCB-8, Quad 1 570 740
+30 1GCB-8, Quad 2 570 1,210
+112 1GCB-6, Quad 4 1,068 980
-8 1GCB-6, Quad 3 1,068 940
-12 1GCB-2, Quad 4 962 860
-11 1GCB-2, Quad 3 962 990
+3 1GCB-4, Quad 4 616 750
+22 1GCB-4, Quad 3 616 2,310
+275 0227u l
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