ML20155F228

Summary of 750205 Meeting W/Util in Bethesda,Md Re Derivation of Dynamic Loads Considered in Design of Containment Structures & Significance of Loads to Overall Loading on Structures.Attendance List Encl

ML20155F228
Person / Time
Site:	Grand Gulf, 05000000
Issue date:	02/14/1975
From:	Butcher E Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20155E140	List: ML20155E133 ML20155E182 ML20155E227 ML20155E338 ML20155E354 ML20155E367 ML20155E405 ML20155E430 ML20155E447 ML20155E473 ML20155E503 ML20155E550 ML20155E557 ML20155E565 ML20155E578 ML20155E600 ML20155E714 ML20155E728 ML20155E753 ML20155E770 ML20155E794 ML20155E948 ML20155E967 ML20155E986 ML20155F001 ML20155F053 ML20155F176 ML20155F191 ML20155F203 ML20155F217 ML20155F228 ML20155F252 ML20155F279 ML20155F302 ML20155F332 ML20155F378 ML20155F477 ML20155F485 ML20155F516 ML20155F534 ML20155F545 ML20155F560 ML20155F589 ML20155G308
References
FOIA-88-91 NUDOCS 8806160317
Download: ML20155F228 (4)

Text

Kf f UNITED STATES NUCLEAR REGULATORY COMMISSION 0 W ASHfNGToH. O. C. 20555 FE.o 14 1975 Docket Nos. 50-416 and 50-417 Applicant

Missis

, -- sippi Power & Light Company Facility: Grand Gulf Nuclear Station Units 1 and 2

SUMMARY

OF MEETING HELD ON FEBRUARY 5,1975 TO DISCUSS THE DERIVATION OF DYNAMIC LOADS CONSIDERED IN THE CONTAINMENT STRUCTURES DESIGN.

A meeting was held on February 5, 1975, at the NRC offices in Bethesda, Maryland to discuss in detail the derivation of dynamic loads considered in the design of containment structures and the significance of these loads to the overall loading on the structures. An attendance list is provided in Enclosure I.

The applicants' Architect Engineer (Bechtel) began the meeting by identi-fying the principal structures that would be subject to loading from sup-pression pool dynamic effects. These structures are: the containment walls, the drywell and wierwell walls, and concrete and metal grating floors at approximately the 120 ft. and 135 ft. elevation. Bechtel draw-ings (No. M-1308, M-1300, M-1207 5 c-1000) were provided for staf f infor-mation and will be made available in the public document room. The pre- -

liminary bounding calculation of suppression pool dynamic loading provided by the General Electric Company in 1972 was used by Bechtel in the design of these structures. The conservatism of these loads is currently being verified by the G.E. Mark III Containment Test Program. The applicants stated that, with exception of the safety / relief valve discharge line loads, a]l suppression pool dynamic loads were supplied by the General Electric Company and the applicants are relying upon GE for justification of the con-servatism of these loads. Bechtel did make a presentation of.their method for calculating loads induced by operation of safety / relief valves. How-ever, the staff expressed strong disagreement with the calculational tech-niques used and the applicants agreed e.o provide additional information to support the correctness and conservatism in their approach, ocutio,k V 5 We.#6

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I Mississippl Power 6 f.ight Co. p

~d The staff noted that.all suppression pool dynamic loads used by Bechtel were assumed to occur symmetrically about the circumference of contain-ment structures. The staff stated that the potential for asymmetrical loading must be considered and the applicant will be required to show that structures will tolerate the loads, or provide justification for assuming that asymnetrical loading effects are not significant. It was noted by all that the General Electric test program is not designed to resolve this concern and, therefore, independent action by the applicants is required.

The applicants summarized the construction progress at the site by stating that they will begin pouring concrete for containment structures' foundations in June or July, 1975. There is about a 1,000 man. construction force on the site now with a peak force of 3,000 men projected for some time in 1976.

Concern wac expressed that concrete for structures subject to suppression pool dynamic loading would be poured before the results of the GE tests were available to verify the etnservatism in the design loads. The staff stated that the validity of suppression pool dynamic loads supplied by G.E. had not yet been agreed to by the staff and that the applicants proceed at their own risk in placing structures whose design is based on. unverified loads. (Note:

PSAR Amendment 18 states' "Floors are presently being designed using a con-servative model to calculate loads induced by suppression pool swell. The desien, however, is capable of being strengthened after construction, .if necessary, to accommodate results of tests underway at General Electric. The floors will be designed for whatever loads the tests show are necessary.")

The staff further stated that the GE Mark III containment test program is designed to provide the neccssary data ta confirm the conservatism of the suppression pool dynamic loads with the exception of loads due to safety /

relief valve operation and asymmetrical considerations. This information must be provided directly by the applicants since the staff evaluation of the results of the G.E.' test program will not resolve this issue.

Tha staff asked several questions in order to determine the significance of suppression pool dynamic loads in the overs 11 loading combinations used in the containment structures design. The applicants were unable to provide I a soecific' break down of the significance of pool dynamic loads as compared with temperature, pressure and hydrostatic loads for each structure. Bechtel stated that the information was available and could be provided. To facili- l tate the staff evaluation of the overall importance of pool dynamic loads, l the applicants agreed to provide the following detailed information for each.  !

structure:

1. The controlling loading combination used for design;

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• Mississippi Power & Light Co. ii

2. The magnitude of each component of the loading combination;

3. The basis (justification) for pool- dynamic loads as they appear in each loading combination (i.e. test data or analytical cal-culation); and

4. References for documentation.of each basis (3. above) for pool-dynamic loads.

It was soggested that.this information could be added to Bechtel Drw.

C-1000 to make uit a more complete document, describing p,ool dynamic load-ing. Also this information will be provided ASAP'and.in advance of other additional information requested so that the evaluation of the importance of suppression pool dynamic loads to the design as it now exists can-proceed prior to.the placing of concrete,

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Edward J. Butcher, Project Engineer

' Light Water Reactors Branch 1-2 Division of Reactor Licensing i

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ENCf.0SURE ATTENDANCE LIST MEETING WITH MISSISSIPPI POWER 6 LIGHT COMPANY ON GRAND GULF FEBRUARY 5 1975 NRC BECHTEL POWER CORP.

E. J. Butcher R. L. Hails

• W. R. Butler J. J. Tkacik V. A. Kudrick C. L. Reid G. C. Lainas F. C. Cheng L. Slegers R. Cudlin MISSISSIPPI POWER & LIGHT

• F. P. Schaver L. F. Dale

• R. L. Tedesco ACRS G.E.

P. T. Burnette N. C. Shirley Z. Zudans

• Part time attendance i

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