ML20195C462

Forwards Final NRC Responses to Questions 6 & 10 Re Control Bldg Mods,Based on Info Provided by Bechtel.Equipment in Structure Should Continue to Be Capable of Resisting Seismic Loadings Resulting from Real Earthquakes

ML20195C462
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	08/21/1978
From:	Goodwin C PORTLAND GENERAL ELECTRIC CO.
To:	Schwencer A Office of Nuclear Reactor Regulation
References
TAC-07551, TAC-08348, NUDOCS 8811030120
Download: ML20195C462 (6)

Text

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'e PORTLAND CsENEMAL E LEcTHrc Cox e.wy sat 5.W. S ALM os Sta tt?

PORTLAND.CncoON 97204 CMA ALES GOO CWIN. JR.

att s*aar c;s.sts.ct=t August 21, 1978 Trojan Nuclear Plant Docket 50-344 License NPF-1 Director of Nuclear Reactor Regulation ATTN Mr. A. Schwencer, mief g 9050 Operating Reactors Branch #1 Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D. C.

20555

Dear Sir:

Attached is the final NRC question and our response based on information provided by Bechtel in confirmation of telephone conversations between Portland General Electric Company (PGE),

Bechtel and the NRC's Ken Herring on August 4, 7, 8, 9, 10 and 16, 1978. We have also included supplementary information to our previous responses (Broehl to Schwencer latter dated August 19, 1978) to the other NRC questions received on the above dates.

This letter and attachments are being served on the Atomic Safety Licensing Board (ASLB) and all parties to the Control Building Hearings.

Sincerely, Y,o*1 C. Goodwin, Jr.

Assistaat Vice President Thermal Operation and Maintenance CG/LWE/TEB/crwtTCBB19 At t achment s 4

8811030120 780821 782360299 POR ADOCK 05000344 P

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NRC STAFF QUESTIONS AND LICCNSEE RESPONSES 1.

Supplement to the Response to Question 6 On Page 9, at the end of the second paragraph, add the s.

following sentence:

"An upper limit for other walls is 6 to 8 times yield".

b.

Delete the last sentence on Page 9. Itse a, and on Page 12, Ites b, and substitute the following:

[

"Table 6-2 gives the breakdown of me.ber capacities for 1

various aspect ratios. As indicated by the table, the.

major portion of the capacity comes from shear walls with aspect ratios less than 0.5."

TABLE 6-2 r

MEMBER CAPACITY AT VARIOUS ASPECT RATIOS CONTROL BUILDING l

Location and Ameet Ratio 'l I

Direction 0-0.5 0.5-0.75

>0.75 l

45'-61' 67(S) 15(S) 18(3)

N8 45'-61' 100(S) 0 0

EW 61'-77' 92(S) 0 8(3)

NS 61'-77' 93(S) 0 7(B)

EW

[a] Aspect ratio = height / length.

(b) The number indicates the percent of the capacity contributed by members having the indicated aspect ratio. The letters 5 or B indicate if the member is controlled by shear or bending, respectively.

2.

Question 10 Describe how the floor response spectra of the Control Building were prepared and how the curves were broadeneJ in the reSion of peak re spons e s.

i l

J Refer to the Licensee submittal of May 5,1978, Figure A-3 and, for example, the Control Building El. 93 f t N-S OBE floor response spectrum. The Fundamental Mode frequency is given as 6.2 Es in Figure A-3.

However, the horizontal portion representing the peak of the response spectrum appears to occur b' tween 4.0 Hz and 6.0 Hz.

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Please explain why the response spectrum broadening is not centered about the fundamental mode frequency of 6.2 Hz.

Also, describe the ef fects on floor spectra of upper bound and lower bound mass and stiffness characteristics of the Control Building.

l Response to Question 10 Floor response spectra were prepared from time history analysis of lumped-mass mathematical models. The mathematical model used for the Control Auxiliary and Fuei Buildings is shown in FSAR Figure 3.7-3, which is reproduced as Figure A-2 in the May 5,1978 Licensee sub-mittal. The derived time history input used in the analysis corre-t sponds to a spectrum which conservatively envelopes the required i

OBE spectrum as shown in FSAR Figures 3.7-6a through 3.7-6c.

In development of the spectra, response accelerations were calculated i

at the following frequencies in Hz, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, O.7, 0.8, 0.9. 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10, 20, i

30, 40, 50, 60, 70, 80, 90, and 100.

After initial plots were pre-1 pared, the spectra were broadened in the region of peak responses i

at the above center frequencies to provide envelope floor response spectra for use in seismic qualification of equipment.

For example, on the El. 93 f t N-S OBE floor response spectrum, the peak accelera-tion of about 5.lg (5 percent damping) calculated at the center fre-tuency of 5 Ez, was held at this peak value from about 4.2 Hz to about 6.3 Ez, which is approximately a + 20% frequency range about 5 Hz.

Trojan SSE floor response spectra were conservatively derived by multiplying OBE derived spectra by a factor of 1.67 which is the ratio of tne SSE peak horizontal acceleration to the OBE peak hori-zontal acceleration. This ratio was held constant throughout the entire frequency range of the spectra for a given damping ratio, hence, the SSE Spectra are very conservative.

Safety-related equipment in the Control Building were qualified by basically three different approaches.

a) For Control Building equipment furnished by Westinghouse, a generic seismic qualification test spectrum for "high seismic plants" was used. This spectrum for test input motion at the equipment mounting has a broadened peak in the frequency range of 5 Hz to 10 Hz, and envelopes the Trojan control room floor accelerations in the N-S, E-W and vertical directions through the frequency range of about 5 Rz to 20 Rs.

Hence, the control roon equipnent supplied by Westinghouse was qualified to levels higher than reauired with respect to the Control Building re s pons e.

b) Most of the other equipment not supplied by Westinghouse was qualified by testing, such as the motor control centers, and was subjected to a sinusoidal vibration scan test to identify r esonant frequencies.

These vibration scans typically showed that such equipment was outside the range of the pean response as shown on the Control Building floor response spectra, and gtnerally ranged from about 15 to 20 Hz.

Some of the equipment, such r.s HVAC control compo-nents, was qualified by subjecting it to test input motion for which the response enveloped the required support point response spectra.

c) The equipment which was qualified by analysis used two methods of calculating responses. Most of this equipment, such as the main control boards, used the response spec-trum peak acceleration without any frequency consideration.

Hence, throughout the entire frequency range, the peak value of the floor response spectra was used for qualifi-ca tion.

Some structurally simple equipment, such as spring-mounted EVAC f an motors, was qualified by calculat-ing the natural frequency and using the floor response spectra to determine the seismic response. This equipment had frequencies either much higher or much lower than the frequency corresponding to the peak value.

The ef fect of reduction in mass together with consideration of elastic stiffness produces a small change in the Control Building floor response spectra.

The reduced mass will result in a slight shif t of the structural frequencies toward the higher frequency range.

Concerning the possibility of inelastic behavior, the ef fective stiffness of the strue ure will decrease and the effective damping vill increase.

The decrease in stif fness will result in a shif t of the structural frequencies, and thus the spectral peak locations, to the lower frequency range.

The increase in structural damping will result in lowering of the spectral peak values. The frequency shif ts due to inelastic behavior may or may not be totally enveloped by the spectrum broadening proc.edure, depending upon the extent of the inelastic action.

Nevertheless, consider-ing the lower spectral values, the compensating ef fect on the spectra of reduction in mass, the vide band nature of the ground spectra and the built-f s conservatiras of the equipment design, the equipment in the structure should continue to be capable of resisting seismic loadings resulting f rom real earthquakes.

TEB/c rwTTCBB22

F UNITED STtTES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of

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Docket 50-344 PORTLAND GENERAL ELECTRIC COMPANY,

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et at

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(Control Building Proceeding)

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(Trojan Nuclear Power Plant)

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CERTIFICATE OF SERVICE I hereby certify that on August 22, 1978, a letter dated August 21, 1978 frem the Licensee to the Director of Nuclear Reactor Regulation with attached "NRC Staff Questions and Licensee Responses", and "Licensees' Answer to ' Notice of Hearing on Order for Modification of License, and of Special Prehearing Conference' and to ' Notice of Eviden-tiary Hearing'" dated August 21, 1978 have been served upon the persons listed below by depositing copies thereof in the United States mail with proper postage af fixed for first class mail.

t Marshall E. Miller, Esq., Chairman Atomic Safety and Licensing Board Atomic Safety and Licensing Board Panel U. S. Nuclear Regulatory Commission U. S. Nuclear Regulatory Commission Washington, D. C.

20555 Washington, D. C.

20555 Dr. Kenneth A. McCollom, Dean Atomic Safety and Licensing Appeal Division of Eng.. sering, Board Architecture and Technology U. S. Nuclear Regulatory Commission Oklahoma State University Washington, D. C.

20555 Stillwater, Oklahoma 74074 Robert M. Johnson, Esq.

Dr. Hugh C. Paxton Assistant Attorney General 1229 - 41st Street 100 State Office Building Los Alamos, New Mexico 97544 Salem, Oregon 97310 Joseph R. Gray, Esq.

Robert Lovenstein, Esq.

Counsel for NRC Staff Lovenstein, Newman, Reis & Axelrad U. S. Nuclear Regulatory Commission Suite 1214 Washington, D. C.

20555 1025 Connec ticut Ave., N. W.

Washington, D. C.

20036 Columbia County Courthouse Law Library Mr. Eugene Rosolie Circuit Court Room Coalition for Safe Power St. Helens, Oregon 97051 215 S. E. 9th Avenue Portland, Oregon 97214 l

Ms. Nina 3 ell l

2018 N. W. Everett 1210 Mr. Stephen M. Willingham l

Portland, Oregon 97209 555 N. Tomahawk Drive Portland, Oregon 97217 I

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CERTIFICATE OF SERVICE (Concluded)

Columbia Environmental Council John H. Socolofsky, Esq.

P. O. Box 611 Assistant Attorney General St. Helens, Oregon 97051 of Attorneys for the. State of Oregon 100 State Office Building Mr. John A. Kullberg Sales Oregon 97310 Route 1 Box 250Q Sauvie Island, Oregon 97231 Cregory Kafoury, Esq.

Counsel for Columbia Environmental Mr. Davii.'. ' S, McCoy Council 348 Husety Lane 202 Oregon Pioneer Building Crants ;**s, Oregon 97526 320 S. W. Stark -

Portland, Oregon 97204 Ms. C. Call Parson 800 S. '/. Creen #6 William Kinsey, Esq.

Portland, Oregon 97205 Bonneville Power Administration P. O. Box 3621 Docketing and Service Section Portland, Oregon 97208 Office of the Secretary U. S. Nuclear Regulatory Commission Washington, D. C.

20555 j

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Ronald W. Jo ~ lo n Attorney for the Licensee I

Dated:

August 22, 1978

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