ML19254B271

Forwards Black & Veatch 790605 Ltr Re Status of Evaluation of Dynamic Loads Imposed Upon Piping Sys by Containment Vessel Responses

ML19254B271
Person / Time
Site:	Black Fox
Issue date:	06/07/1979
From:	Jason West PUBLIC SERVICE CO. OF OKLAHOMA
To:	Gallo J ISHAM, LINCOLN & BEALE
Shared Package
ML19254B263	List: ML19254B262 ML19254B265 ML19254B270 ML19254B271
References
NUDOCS 7909270038
Download: ML19254B271 (3)

Text

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~"r PUBUC SERVICE COMPANY OF OKLAHOMA rz g  : 1 f, A CENTRAL AND SOUTH WEST COMPANY r; v

. .. g P O. BOX 2o1/ TULSA. OKLAHOMA 74102 / (9181583-3611 Q PubliC Service Company of Oklahoma June 7, 19790 Black Fox Station JUH 141979 7'\

Lb Mr. Joseph Gallo Isham, Lincoln, & Beale 105017th St. N.W. , 7th Floor Washington, D. C. 20036

Dear Mr. Gallo:

Attached for your information is a letter to PS0 summarizing the status of the

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g Black & Veatch evaluation of a problem due to dynamic loads imposed upon piping systems by containment vessel responses. This letter summarizes information presented to PS0 in a ma.1agement information meeting on May 31.

PSD is considering the B&V evaluation and recommendations and will provide B&V wi~th cur guidance in the near future.

Very truly yours, Jo n B. West 'y M nager, BFS Engineer 1hg JBW:dm Attachment c

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TEL ( 913 ) 967 2000 CONSULTING ENGINEERS TELEX 42 6263 ISCO M EAOOW LAME PARMWAY amuno moonass. p.o. som wo. esos MANSAS CITY. MISSOU Al 64884 Public Service Company of Oklahoma B&V Project 6212 ,

Black Fox Station File: 6212.215.3230.21 Reactor Building Containment Vessel June 5,1979 Public Service Company of Oklahoma P.O. Box 201 Tulsa, Oklahoma 74102 Attention: Dr. J. B. West Manager, BFS Engineering Gentlemen:

The purpose of this letter is to summarize the status of our design efforts regarding the phenomena of containment vessel ringing. This phenomena refers to the calculated responses associated with safety / relief valve (S/RV) loading combinations. These responses are characterized by small deflections, moderate containment stresses, and high acceleration values. Although

, containment vessel ringing does not significantly effect the design of the containment vessel, the acceleration portion of the response does govern the design of those piping systems and steel framing that are attached to the vessel..

As you recall, General Electric completed their definition of S/RV related design criteria in the spring of 1976 and received technical concurrence from the NRC Staff o July of 1976. These criteria included the definition of peak bubble pr ssure for all S/RV applications in suppression pool boundary loads for the design of structures. Suppression pool boundary loads for determining building response required further work. In November of 1977 General Electric presented a seminar on the NSSS Load Adequacy Program which included proposed procedures for evaluating S/RV loads and determining building response. During the application of these procedures, B&V identified the response phenomena which was later identified as containment vessel ringing. At that point in time, May of 1978, the. primary areas of engineering investigations were the resultant stresses in the vessel shell which were found to be moderate in magnitude. Shortly thereafter, it was recognized that although ringing does not significantly effect the design of the containment ve _el, it did govern the design of attachments to the vessel.

Two approaches were initiated to resolve the ringing phenomena. The first approach was to completely review the method of analysis. The intent of this effort was to develop a more realistic analytical solution to the concern and take advantage of on-going General Electric Company's confirmatory

( testing relating to S/RV a:tuation. The second was to investigate the potential hardware fixes which would reduce the ef fects or mitigate l

- the vessei response.

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l. 1045 004

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Public Service Company of Oklahoma B&V Project 6212 Black Fox Station June 5, 1979 k.

In late March of 1979, GE informed PSO/B&V that GE did not recommend analytical solutions for resolving the ringing phenomena. GE felt that the cost / benefit ratio of a research and development program to resolve the matter were too high, and therefore, recommended hardware fixes to mitigate vessel response. At this point in time B&V accelerated investigations into alternate ways to mitigate the vessel response. The options reviewed and recently discussed with you included the following:

1. Modifying the free standing steel containment veasel by the addition of vertical stiffeners and a second concentric shell plate and modifying the existing horizontal stiffeners to provide a large bulkhead on the containment exterior in the suppression pool area.

2. Extending the foundation mat concrete up the outside of the contain-ment to the top of the suppression pool. The containment vessel 5ould begin at the top of the extended base mat. The vessel shell would be supported by the extended mat and be anchored in the existing basement.

3. Adding horizontal, radial pipe support struts which . the ontainmen t vessel stiffening systen to the shield building.

We have completed our raview of the options and taking into consideration the current project schedule we recommend implementation of option 3, adding

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horizontal, radial pipe support struts between the containment vessel and the shield building. These struts restrain containment vessel motion and thereby reduce structural response of the vacael. The containment vessel would function as a Class MC vessel with or without the supporting struts.

The influence of the struts on the vessel would be considered in the design of the vessel, however, the struts would not be relied upon to reduce the design requirements for the containeent vessel. The struts would be relied upon only to reduce the structural response of the structure and the effects of the response on the attachments to the vessel.

We are proceeding with the development of revised structural response data and the incorporation of the strut design into the containment vessel, shield building, and the foundation mat. Currently, we do not unticipate significant changes to any of these structures other than the addition of embedments in the shield building and modification of reinforcing steel and wall thickness in the lower region of the shield building..

Should you have any questions concerning the course of action outlined above, please contact us.

I Very truly yours, BLACK & VEATCH

( e C. J. Ross dh 1045 005