ML20155F545

Forwards Request for Addl Info Re Mark III Containment Suppression Pool Dynamics,Per 750820 Request to Review Subj Rept

ML20155F545
Person / Time
Site:	Grand Gulf, 05000000
Issue date:	10/16/1975
From:	Maccary R Office of Nuclear Reactor Regulation
To:	Deyoung R Office of Nuclear Reactor Regulation
Shared Package
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References
FOIA-88-91 NUDOCS 8806160424
Download: ML20155F545 (5)

Text

i UNITED STATED -

o NUCLEAR REGULATORY COMMissl0N s W ASHINGTON. D, C. 20555 *

- I

( Docket Nos. 50-416 ,

and 50-417 OCT 16 gg R. C. DeYoung, Assistant Director .

for Light Water Reactors, Group 1 Division of Reactor Licensing TECHNICAL ASSISTANCE REQUEST (T.'M 1579), GRAND GULF UNITS 1 & 2 MARK III CONTAINMENT SUPPRESSI0' 100L DYNAMICS In accordance with your request dated August 20, 1975, the Structural Engineering Branch has reviewed the report on the subject matter. We find that additional information is required before the review and

• evaluation can be completed. The information required together with-staff positions is contained in the enclosure.

i c ww 'l'}. e .

R. R. Maccary, Assistant Director for Engineering Division of Technical Review

Enclosure:

As Stated cc w/o encl:

W. G. ficDonald R. S. Boyd cc w/ encl:

R. E. Heineman R. Tedesco LGM.ainas J. Knight W. Butler E. Butcher L. Shao K. Kapur I. Sihweil F. Schauer R. Stuart C. Tan 8806160424 880602 PDR FOIA CONNOR B8-91 PDR 4/17-

.= . . - - ._

i, GRAND GULF UNITS 1 & 2 i MARK 111 POOL DYNAMICS REQUEST FOR ADDITIONAL INFORMATION t STRUCTURAL ENGINEERING BRANCH

1. Explain or correct the following inconsistencies and over-stresses in the computations:

a) On Page 26, the meridional force, Np , for T owith a cracked section is zero, but is 8 kips with an uncracked section; on Page 27. for (To + T,) with an uncracked section Nr is zero.

b) On Page 27, it appears that the membrane tension due to N r is not large enough to offset the compression due to Mr . Therefore ,

the concrete stress, fe, corresponding to f' = 43,700 psi should not be zero. Also clarify the inconsistency between 1.0 (To + T,)

uncracked and f = O psi (section completely cracked).

c c) The maximum stress in the diagonal reinforcement of the containment is listed as 59,200 psi on Page 30. The stress in reinforcement should be limited to 0.9fy for such load conditions. Justify the apparent overstress.

d) On Page 33 under. Item b,cf is shown to be -6.1 ksi. Indicate the concrete strength used in your design. If this is higher than the specified strength, justification should be provided for the use of concrete strength over that specified, e) On Page 35 under Item b., f is shown to be -326.824 ksi. Such a s

high stress is unacceptable and should be explained or corrected.

2. The explanation provided on Page 52 regarding the use of 1.0 load factors for pool swell and SR/V discharge loads is not acceptable.

Conservatism in the load is not a sufficient basis for reduction in load factors. If the load is ultra conservative, the staff suggests the use of appropriate loads and appropriate load factors. The pool swell and main steam / relief valve (SR/V) discharge loads should be treated as indicated in the attached NRC staff position regarding load t

factors and load combinations for BWR Mark III Containment Pool Dynamic Loads. Any deviation from the attached position should be justified.

3. On Pages 54 and 57 the use of elasto-plastic analysis is indicated for floors subject to bulk and froth swell. The staff will permit elasto-plastic analysis & design due to pool swell only for floors, ,

walkways and grating which do not support safety related equipment.

However, acceptable maximum design ductility ratios used therewith must be specified in the PSAR. ,

4. On Pages 55 and 56 a discussion is presented regarding thermal stresses offsetting mechanical stresses. It is apparent from Pages 26-30 that thermal stresses were utilized to offset mechanical stresses.

This is not considered acceptable. Revise the calculation and design, if required, accordingly.

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. October lo, 19h STRUCTURAL ENGINEERING BRANCH POSITION I ' U.S. NUCLEAR REGULATORY COMMISSION BWR MARK III CONTAINMENT P0OL DYNAMICS

1. POOL SWELL

a. Bubble pre, sure, bulk swell and froth swell loads, drag pressure and.other pool swell loads should be treated as abnormal pressure loads, Pa . Appropriate load combinations and load factors should

be applied accordingly.

b. The pool swell loads and accident pressure may be combined in .

accordance with their actual tine dependent mutual occurrence.

2. SAFETY RELIEF VALVE (SR/V) DISCHARGE I '

a. The SR/V loads should be treated as live loads in all load combin-ations with the exception of the combination that contains 1.5P a where a load factor of 1.25 should be applied to the appropriate

- SR/V loads, l A single active failure causing one SR/V discharge must be considered in combination with the Design Basis Accident (DBA). j j Appropriate multiple SR/V discharge should be considered in combin- l

ation with the Small Break Accident (SBA) and Intennediate Break l Accident (IBA). ,

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d. Thermal loads due to SR/V discharge should be treated as oT for nonnal operation and T for accident conditions. .

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