ML19338D403
| ML19338D403 | |
| Person / Time | |
|---|---|
| Issue date: | 07/09/1980 |
| From: | Catton I Advisory Committee on Reactor Safeguards |
| To: | Savio R Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-1269, NUDOCS 8009230113 | |
| Download: ML19338D403 (1) | |
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July 9, l9'80
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FROM:
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SUBJECT:
ADVANCE 0 REACTOR SAFETY RESEARCH SIMMER as it'is presently constituted is weak in'a number'of respects.
Limitations are imposed by: assuming a droplet field:and associated ~assump-tions regarding drop size and heat' transfer. The droplet field is a mixture-of,UO2 and steel drops and'no segregation'is allowed. The observed tight coupling of neutronics to' heat transfer and fluid dynamics is not surprising but points out the_ neeri for. putting the thermal: hydraulics on a sound footing.
SItEER does not. include thermal radiation as a heat transfer path.. At this time, calculations of accident sequen'ces'can have little meaning and'may' t
even beJcounterproductive.- The.SItHER code development does not seem to have evolved very much'during the past-several years.
It may be that the desired goals cannot-be achieved.
In any event, much more attention:needs to be paid
- to the physical processes being modeled and loss to running the code.
I see
' very little in the future plans for SIMMER that will make it better.
A number of. excellent. experimental programs are being conducted at SANDIA..
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The transition phase' experimental program being based on behavior of 3 mm fuel pin-deserves some justification. The small scale may change the course of
~ events. The. experiment where a coarse pre-dispersed mixture in sodium is pulsed will' yield a great; deal of information on'FCIs. Further, in-pile bed dryout experiments'are not needed.
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