ML19318C677
| ML19318C677 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 12/13/1979 |
| From: | Mattson R Office of Nuclear Reactor Regulation |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| TASK-AS, TASK-BN-79-42 BN--79-42, BN-79-42, NUDOCS 8007020151 | |
| Download: ML19318C677 (2) | |
Text
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MEMORANDUM FOR:
D. B. Vassallo, Acting Director, Division of Project Management FROM:
Roger J. Mattson, Director, Division of Systems Safety
SUBJECT:
EFFECT OF F0AM GLASS INSULATION ON POST-LOCA COOLING The November 26, 1979 memo addressed to me from Steven Varga, addressed a potential concern regarding post-LOCA flow blockage for certain PWR plants (such as Midland) based on insulation type and sump screen mesh size.
It requested an evaluation of the concern in regard to possible board notification.
At this time, B&W is the only vendor which has indicated concern on the issue of flow blockage due to small particles of insulation being carried into the core following a LOCA. However, we believe that this may be a generic problem affecting any plant which uses this type of insulation.
During LOCA blowdown, foam glass insulation could be broken down into a
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small grit, which could become trapped between the fuel spacer grids and fuel elements, causing flow blockage and degrading post-LOCA cooling.
Additionally, this grit would be pumped through the low head safety injection pumps causing possible impeller deterioration or bearing damage.
To' prevent the insulation material from being drawn into the core, the Midland plant is using a very fine sump mesh screen. The potential for large screen i
blockage due to this insulation must be considered, along with corresponding degradation of recirculation sump performance.
In order to evaluate the seriousness of the above concerns, more information is needed from.CE_AtL OL applicanti Please have all aoolicants describe j
d the types oE pfping insulation used within containment and whether they would i
expect that insulat'io5To break down into particles following a LOCA.
For those plants which have insulation which is expected to break down (such as foam glass), obtain the expected particle size and an evaluation of what effect these particles would have on post-LOCA core flow. Also obtain infonnation on the screen sizes used in the recirculation sump.
Contact:
Mark Rubin, NRR 49-27591
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6007020%.
O U. B. Vassallo Occ ! 3 ms With the above requested infomation, we will be able to identify which boards
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should be notified of this concern. Due to the potential seriousness of the concern, please have the applicants respond within 14 days of the irceipt of s.
this request. By copy of this mem we arg,, identifying the above c;r:c2rns totheDivisionofOperatingReactg,sfortessibleaction.
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Roger J. Mattson, Director y
Division of Systems Safety cc:
D. Ross D. Eisenhut V. Stello, IE H. Thornburg, IE S. Hanauer T. Speis S. Varga J. Watt F. Orr M. Williams D. Hood M. Rubin TERA C
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