ML20081B066

Interim Deficiency Rept Re Reactor Bldg Spray Piping Supports.Initially Reported on 791221.Caused by Conservative Modeling Assumptions Made in Original Water Hammer Analysis. Next Rept by 831230

ML20081B066
Person / Time
Site:	Midland
Issue date:	10/21/1983
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, 23826, 78-05-#14, 78-5-#14, MCAR-22, NUDOCS 8310270265
Download: ML20081B066 (6)

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{Q lQf Vice President - Projects, Engineering and Construction General officu: 1945 West Pernell Road, Jackson, MI 49201 + (517) 788-0453 October 21, 1983 78-05 #14 Mr J G Keppler, Regional Administrator US Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 MIDLAND NUCLEAR COGENERATION PLANT DOCKET NOS 50-329 AND 50-330 REACTOR BUILDING SPRAY PIPING SUPPORTS FILE:

0.4.9.17 SERIAL:

23826

Reference:

1) CPCo (S H 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

3) CPCo Serial 22254, dated July 11, 1983 This letter, as were the referenced letters, is an interim 10CFR50.55(e) report concerning Reactor Building Spray Anchors. 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 December 30, 1983.

H, L-JWC/WRB/cd A

Attachment:

MCAR 22, Addendum 1, Final Report CC: Daryl S Hood, USNRC, Bethesda, MD Document Control Desk, NRC, Washington DC RJCook, NRC Resident Inspector, Midland, MI INFO Records Center, Atlanta, GA 8310270265 831021

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OC1083-0016A-MP01 2 gn/3 g

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78-05 #14 Serial 23826 OM/0L SERVICE LIST Mr Frank J Kelley Atomic Safety & Licensing Attorney General of the Appeal Board State of Michigan U S Nuclear Regulatory Commission Ms Carole Steinberg, Esq Washington, DC 20555 Assistant Attorney General Environmental Protection Division Mr C R Stephens (3) 720 Law Building Chief, Docketing & Services Lansing, MI 48913 U S Nuclear Regulatory Commission Office of the Secretary Washington, DC 20555 Mr Myron M Cherry, Esq Suite 3700 Ms Mary Sinclair Three First National Plaza 5711 Summerset Street Chicago,~IL 60602 Midland, MI 48640 Mr Wendell H Marshall Mr William D Paton, Esq RFD 10 counsel for the NRC Staff Midland, MI 48640 U S Nuclear Regulatory Commission Washington, DC 20555 Mr Charles Bechhoefer, Esq Atomic Safety & Licensing Atomic Safety & Licensing Board Panel Board Panel U S Nuclear Regulatory Commission U S Nuclear Regulatory Commission Washington, DC 20555 Washington, DC 20555 Dr Frederick P Cowan Ms Barbara Stamiris 6152 N Verde Trail 5795 North River Road Apt B-125 Rt 3 Boca Raton, FL 33433 Freeland, MI 48623 Mr Fred C Williams Mr Jerry Harbour Isham, Lincoln & Beale Atomic Safety & Licensing 1120 Connecticut Ave, NW, Suite 325 Board Panel Washington, DC 20036 U S Nuclear Regulatory Commission Washington, DC 20555 Mr James E Brunner, Esq Mr M I Miller, Esq Consumers Power Company Isham, Lincoln & Beale 212 West Michigan Avenue Three First National Plaza Jackson, MI 49201 52nd Floor Chicago, IL 60602 Mr D F Judd Mr John Demeester, Esq l

Babcock & Wilcox Dow Chemical Building PO Box 1260 Michigan Division Lynchburg, VA 24505 Midland, MI 48640 i

Mr Steve Cadler, Esq Ms Lynne Bernebei l

2120 Carter Avenue Government Accountability Project l

St Paul, MN 55108 1901 Q Street, NW Washington, DC 20009 t

l September 6, 1983 OC1083-0016A-MP01

<.t31)612 Bechtelggiates Professional Corporation

SUBJECT:

MCAR 22 (addendum issued 1/26/83)

Reactor Building Spray system r

FINAL REPORT DATE:

October 3, 1983 PROJECT:

Consumers Power Company Midland Plant Units 1 and 2 Bechtel Job 7220 Description of Deficiency A modeling assumption that resulted in less conservative results was discovered in the original reactor building spray system water hammer analysis. Some of the recalculated water hemmer pressures are higher i

than those calculated in the original analysis.

Summary of Investimation BechtG1 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 +275% 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, 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 Implication 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 ensures that the reactor building spray header will l

l remain intact to perform these safety-related functions. The l

calculation of water hanner 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 0470u l

I306l2 Bechtel Associates ProfessionalCorporation l

MCAR 22 FINAL RRp0RT Page 2 analysis completed in 1979. The preliminary stress analysis using the revised modeling assumptions has indicated that the stress allowables are exceeded.

The impact on the safety of operation of the plant had this condition remained uncorrected is indeterminate. Rather than continue analysis or testing to determine the safety impact, it was decided to revise the system design to ensure its adequacy using conservative analyses.

l probable Cauge The increased loads observed on piping and piping anchors were caused l

by simplified modeling assumptions made in the original water hammer l

analysis that appeared reasonable at the time, but were subsequently found to be less conservative in certain cases.

Corrective Action The following actions have been initiated:

1.

Deslan Review of the pipinz. Manter 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:

a.

Model testing in conjunction with any required support system 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 i

follows:

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fl30612 Bechtel Associates Professional Corporation IS0529 BCAR 22 FINAL REPORT f

Page 3

1) Revise water hammer force time histories based on revised piping design. This activity is currently being completed.

Preliminary results indicate a significant reduction in water l

hammer forces.

2) Obtain as-installed key dimensions of piping anchors. This activity is complete.

l

3) Revise the piping stress analysis. This activity is currently in progress.

I

4) Issue piping isometrics. This activity is currently in l

progress.

5) Perform testing of pipe hangers. This activity is currently l

in progress.

6) verify or modify the piping support system to bring it within allowables.

7) Issue design drawing for support system modifications.

An engineering production schedule (EPS-7002) has been issued to coordinate these activities. The anticipated completion of all construction activities for Unit 2 will be before the Unit 2 testing milestone 2J (hot functional testing) currently scheduled for May 5, 1984.

I 2.

Determination That the Modelina Assumptions in Ouestion Were Not Used in Other Water Hammer Analyses on the Midland Proiect A summary of the modeling assumptions and their use has been distributed to other Bechtel AAO project and staff entitles performing water hammer 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.

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P: e 4 Reportability Consumers Power Company reported this condition to the NRC on January 25, 1983, under the criteria contained in 10 CFR 50.55(e).

Submitted by:

f d O.. l le M & v W.A. Skelley

[

Nuclear Systems Group supervisor Approved by:

kflA 4)y E.M. HugheA SProject Engineer Concurrence by:

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GeotechnicalServicesMa[ nager

.'C. Pacif Jr.' '

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fU-Concurrence by:

/C*d*3 a m o(

R.L. Loos Chief N cles Engineer i

Concurrence by:

E.H. Balth Engineering Manager Concurrence b :

hr M.A. Dietrich[ Assurance Project Quality Engineer I

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