ML20203K853

Responds to NRC Re Allegation Concerning Adequacy of Pipe Whip Restraint Design.Project Records Placed in Storage & Personnel Performing Work Dispersed.Specific Design Approach Would Require Check of Records at Bechtel

ML20203K853
Person / Time
Site:	Midland
Issue date:	04/23/1986
From:	Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Berkow H Office of Nuclear Reactor Regulation
References
32648, NUDOCS 8605010065
Download: ML20203K853 (2)

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00nSufntf5 Power Jemse W cook C0mpany . n<, ~,u- - ~,u,o. .,m.,

end t:0.nnc,wn General officas: 1945 West Pornoit soad, Jackson, MI 49201. (SIN 788 0453 April 23, 1986 Mr Herbert Berkov, Director Standardization and Special Projects Directorate Division of PWR Licensing-B US Nuclear Regulatory Commission Washington, DC 20555 MIDLAND ENERGY CENTER DOCKETS No 50-329 AND 50-330 PIPE WHIP RESTRAINT DESIGN FILE: 0.4.9.41, 0.4.9.44, 1300 SERIAL: 32648

Reference:

Letter, H Berkow to J W Cook, Pipe Whip Restraints Design for Midland Nuclear Plant, Units 1 and 2, dated March 12, 1986 The referenced letter informed us that an allegation had been made concerning the adequacy of pipe whip restraint design and requested our response to specific questions regarding the design of the primary loop whip restraints.

Since the Midland Project was shut down, the project staffs, at CPCo Bechtel and B&W have been demobilized, the project records have been collected and placed in storage, and the people who performed this work have dispersed. At this time personnel who are technically knowledgeable of the design of the Midland RCS whip restraints are not readily available. Consequently, an effort has been made to address this request, first by surveying the records available within CPCo, which does not include restraint design calculations, and by discussions with B&V and a former CPCo employee who participated in development of design criteria for whip restraints. To confirm any specific design approach in individual restraints would require considerable resources to resurrect the specific records at Dechtel.

Design of Midland RCS pipe whip restraints required the efforts of both B&W and Bechtel. B&W performed all analysis on RCS piping. Bechtel designed and constructed all pipe whip restraints. Since the load applied to a restraint in dependent on the stiffness of the restraint, the process of establishing pipe whip loads, and of designing restraints, is an iterative one involving the exchange of design information between B&W and Bechtet.

This information exchange process benefited from improvements described in 50.55(e) report 80-07, concerning Reactor Coolant Loop Analysis. A previous OC0486-0019A-MP02 f605010065860423 DR ADOCK 05000329 A ig PM

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design. A final report is outstanding for this later subject as some l restraint redesign was still ongoing.

The following paragraphs address the specific items of the Request for Additional Information:

l 1. The load combinations that were used in the design and analysis of the reactor coolant hot leg pipe whip restraints are given in Subsection 3.8.6.3.3 of the Midland FSAR, under the heading of "b. Structural Steel." The restraints are designed such that the pipe never contacts them, except during the pipe break event.

Ib. In the load combination equations, the term "R" is defined as the " local L force or pressure on structure or penetration caused by rupture of any one pipe." This term includes the load applied by the broken pipe as

( vell as the jet impingement loads from the break. Design of the Midland plant was such that, except for the upper lateral supports on the reactor vessel, compartment pressurization did not produce a significant load on an RCS restraint.

Ic. Part of B&W's responsibility in analyzing the NSSS piping was to determine the required gap at each RCS restraint. The minimum pipe restraint gap is the sum of the construction tolerance plus the thermal expansion motion of the pipe plus the expected SSE seismic motion of the pipe. The seismic motion of the structures and the pipe are small, and were conservatively assumed to be out of phase. Refer to Midland FSAR Figure 3.7-9, 3.7-25 and 3.7-30 for a description of the model, and the calculated structure displacements.

2. The methods used to compute spring rates for the pipe whip restraints connected to the secondary shield wall varied with the complexity of the structure. For complex structures, three dimensional finite element analysis was used. For simple structures, such as straps, hand calculations were done. In general, the complexity of the structure was annessed, and the appropriate engineering methods applied.

3. Subsection 3.8.6.3.3 of the Midland FSAR describes the stress criteria l

that were applied to pipe whip restraints. Where pipe whip restraints i

were designed to incur plastic deformation, they were designed such that

' the maximum strain was no greater than one quarter of the ultimate strain

! for the specific material being used.

We trust the above responds to your request for additional information.

h yfg CC: JGKeppler, USNRC Region 111 TSMichaels, USNRC Office of NRR OC0486-0019A-MP02

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UNITED STATES 4 g j' ,,, 7 * *j NUCLEAR REGULATORY COMMISSION b"'

wasmmatou.o c.rosss March 12, 1986 k ..... f Dockets Nes. 50-329 and 50-330 Mr. J. W. Cook, Vice President Consumers Power Company 1945 West Parnall Poad Jackson, Michigan 49201

SUBJECT:

PIPE WHIP RESTRAINTS DESIGN FOR MIDLAND NUCLEAR PLANT, UNITS 1 AND 2 The NRC staff has received an allegation regarding the adequacy of the pipe whip restraint design for Midland Units 1 and 2 and an assertion that this issue c y apply to other B&W designed plants. The allegation relates to (1) the load conbinations used in the design and analysis of reactor coolant hot leg restraints; and (2) the spring rates of connections of pipe whip restraints to the secondary shield wall.

The staff finds that your respense to the enclosed reouest for additional information is needed to complete our review of this allegation. Please provide your response within 45 days of the date of this letter, finerely, Herbert Berkow, Director Standardization and Special Proiects Directorate Division of PWR Licensing-B

Enclosure:

Request for Additional Information cc w/ enclosure:

See next page

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2 Mr. J. W. Cook Consumers Power Company Midland Nuclear Plant cc:

Michael I. Miller, Esq. Mr. Don van Farrowe, Chief Ronald G. Zamarin, Esq. Division of Radiological Health Alan S. Farnell, Esq. Department of Public Health Isham, Lincoln & Beale P. O. Box 33035 Three First National Plaza. Lansing, Michigan 48909 Sist floor Chicago, Illinois 60602 Mr. Steve Gadler 2120 Carter Avenue James E. Brunner, Esq. St. Paul, Minnesota 55108 Consumers Power Company 212 West Michigan Avenue Ms. Barbara Stamiris

\8 Jackson, Michigan 49201 5795 N. River

• Freeland Michigan 48623 Ms. Mary Sinclair 5711 Summerset Drive Mr. Tom McNish, Secretary Midland, Michigan 48640 Consumers Power Company l 212 W. Michigan Avenue Stewart H. Freeman Jackson, Michigan 49201 Assistant Attorney General State of Michigan Environmental Mr. Walt Apley Protection Division c/o Mr. Max Clausen 720 Law Building Battelle Pacific Northwest Labs Lansing, Michigan 48913 (PNWL)

SIGMA IV Building Mr. I. Charak, Manager Battelle Blvd.

NRC Assistance Project Richland, Washington 99352 Argonne National Laboratory 9700 South Cass Avenue Mr. R. B. Borsum Argonne, Illinois 60439 Nuclear Power Generation Division Babcock & Wilcox Regional Administrator, Region III 7910 Woodmont Avenue, Suite 220 U.S. Nuclear Regulatory Commission, Bethesda, Maryland 20814 799 Roosevelt Road Glen Ellyn Illinois 60137 Cherry & Flynn Suite 3700 Ms. Julie Morrison Three First National Plaza Midland Daily News Chicago, Illinois 60602 124 Mcdonald Street Midland, Michigan 48640 Mr. Ron Callen Michigan Public Service Commission Billie Pirner Garde 6545 Mercantile Way Director, Citizens Clinic P. O. Box 30221 for Accountable Government Lansing, Michigan 48909 ,

Government Accountability Project Institute for Policy Studies Mr. Howard Levin, Project Manager 1901 Que Street, N.W. TERA Corpnration Washington, D. C. 20009 7101 Wisconsin Avenue Ms. Lynne Bernabei Government Accountability Project 1901 0 Street, N.W.

Washington, D.C. 20009

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Enclosure REQUEST FOR ADDITIONAL INF0PPATION

1. Describe the lead corbinations that were used in the design ard analysis of reactor coolant hot leg pipe whip restraints. Specifically, indicate if the load corbinations included the consideration of

a. loads from jet irpingment and corpartrent pressurization of tne secordary shield wall,

b. seismically induced displacement of the secondary shield wall.

2. Describe how the sprina rates of connec'. ions of pipe whip restraints to the secondary shield wall were compu*ed.

3. Describe the allowable stress or strair used in vour design, i

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