ML20104A137

Provides Addl Generic Comments Re Topics Discussed at 781116-17 Zimmer Subcommittee Meeting.Topics Include Reactor Vessel Supports,Fuel Bundle Lift,Suppression Pool Downcomers,Lateral Loads & Control Drive Tube Location

ML20104A137
Person / Time
Site:	Zimmer
Issue date:	11/30/1978
From:	Catton I CALIFORNIA, UNIV. OF, LOS ANGELES, CA
To:	Savio R Advisory Committee on Reactor Safeguards
References
ACRS-1077, NUDOCS 7902260217
Download: ML20104A137 (2)

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• Univeroity of Califctnia Leo Ang21cs, California 90024 November 30, 1978 Q.,-/[/, anca m s 'i ASTLMit? comm TTtt oe.  !

1tActoa soscuanas u.s. a d To: Dr. R. Savio From: Ivan Catton 4 4, Pa!

Subject:

Zimmer Subcommittee Meeting,16-17 November 197I1 8 htkkE13M445,6 Copies To / M. Bender, M. S. Flesset J. Ebersole -

l I would like to add a few conuments to several of the topics discussed at the Zimmer Subcommittee Meeting. They'are more generic than specific in

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Reactor Vessel Supports. One of the contributors to reactor vessel support load'ing is non-uniform pressure in the annulus around tne vessel.

The annulus pressures are calculated using a one-dimensional code when the

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phenomena is clearly two-dimensional. Large pressure variations exist and the flow being two-phase results in soniEconditions being predicted to exist gif between volumes specified for analysis., This is accomodated by the analyst

- ::, T using a Moody coefficient approach. Itlis not clear to me that th6 predictsd y

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I pressures are realistic or conservative.. ,

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Fuel' Bundle Lift. Fuel bundle lift potentisl during the blowdown phase l

of a LOCA, a concern of Mr. Dersola, is' not fully addressed in any document.'

I have access to. As far as I can tell, the upward force en the feel hundle is based on and of channel life friction 'with and of life being defined as the time at which the' friction between the control rod and the assembly wall is high enough to impede withdravel of the control rod. With this x

definition'the upward force,ambunts to 107 lbg . Ihe downward force, corrected for water buoyancy,'is 300 lbg . The net is then about 200 lb g in the downward i

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I - (direction *, Duri:3 blowdown, the pre: sura in the byp:co region fc11o footor th n in tha fuol bund 10 ccu3ies o escreato in tha bundio to bundio gsp. It is not inconceivable that a several fold increase in  ? te: ion factor night result and the 200 lb margia might disappear. It is possible that I have f

missed an important aspect of the problem. If so, I would like to review the documents clarifying how the fuel bundle lift question is put to rest. l

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l Suppression pool Downconers and Lateral Loads. The dovr. comers are over thirty feet long and have no lateral restraints. The magnitude of the lateral loads. depends strongly on the suppression pool temperature and l . ..

downconer assa flux. . At a result the loads very with time.

If the pool temperature remains low enough, large lateral loads do not occur and my l concerns are not well founded. To assess the potential for large lateral

f. loads, the po'o1 temperature and downcomer mass flux time histories are needed. The pool temperature must properly account for stratification.

j- Some consideration should al'so be given to the geometric arrangement of the

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eighty or sb downconers and possible interact: ions as. the data base is pri-marily the,4T tests. The submersuce is ten feet and restraints, if needed,

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f could be submerged alininating concern about pool'evell, impact' loads. -

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. Control Drive Tube fececion. The contro.l. , ,

- . ,. rod drive tubes ~are located

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_ . y.very close. to the recirculationjline with half of the tubes being on each i

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side of the vessel. The tubes are routed so that if half are lost, due to ,

a pip break; the remaining can still scram' the reactor. It seems to me that the possibie lo,ss of half your control-drive tubes is an important consideration and maybe they ought to be les's exposed. .

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