ML19221A589

Task 109:assessment of RCS Behavior in Percolating Mode Before Large Amounts of Noncondensibles Buildup

ML19221A589
Person / Time
Site:	Crane
Issue date:	04/09/1979
From:	Thiesing J INDUSTRY ADVISORY GROUP
To:
References
OSP-790409, TASK 109, TASK-109, NUDOCS 7905230258
Download: ML19221A589 (1)

Text

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((/8 To:

Milt Levenson Date: April 9, 1979

Subject:

RCS Behavior From:

J. W. Thiesing Copies:

J. C. Judd Of:

TMI - IAG The following is an assessment of RCS behavior in the "perculating" code before large amounts of noncondensibles build up:

Initial Conditions n

W 2.

1.

Secondary side solid -- cold water

/

2.

Pressurizer vented to containment atmosphere, either by relief valve open or through 3/8" sample line re-plumbed to containment.

3.

Primary system solid head or on head tank 4.

Core flood tanks floating -- either under N2 5.

Little or no non-condensibles 6.

RC pumps off 7.

Assu=e littic or no natural circulation

, Behavior 1.

Heat generatio7. in core will form steam 2.

Steam will form trubble in top of vessel 3.

Steam bubble will displace water and raise pressurizer level (amMeerd-tuh ', J J in W4 4.

When bubble uncovers top of hot legs, stean will (eventually) slide out hot leg, forming bubble at top of candy cane quite rapidly (roughly 5000 - 10000 cfm).

N 5.

The increasing bubble volume continues to drive water into pressurizer (er4-

--- 9 eel, tf r % C L. 4 P

6.

The increasing bubble volu=e in candy cane uncovers cold tubes in steam l

generator until such time as the condensing rate in steam generator equals q'

or exceeds the steaming rate in the core.

7.

Then, a.

If the system is heavily damped, a steady state steaming in core / condensing in steam generator condition will result.

gr, b.

If the system is undamped which is uore likely the bubble in the steam generator and candy cane will collapse rapidly, and the process will begin at Step 3 above again and repest itself, ad infinitum.

In this mode before significant non-condensibles build up, I do not believe there will be any.perculating through the pressurizer, only a rising and falling of water level in the pressurizer.

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