ML20237L643
| ML20237L643 | |
| Person / Time | |
|---|---|
| Issue date: | 07/12/1987 |
| From: | Catton I Advisory Committee on Reactor Safeguards |
| To: | Boehnert P Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-1895, NUDOCS 8708280194 | |
| Download: ML20237L643 (2) | |
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CT-/895 TO:
Peul Boehnert 12: Ju1O987 -
l FROM:
Ivan Catton s'
SUBJECT:
T/H Research Program A good T/H research program needs to be directed towards yielding meaningful information. To be sure a given program will do so l
requires that the need be clearly stated and that a state of the art review be made to be certain that the need really does exist.
i One must sort out questions about reactor system behavior and leek of ability to predict its behavior. For example, the OTSG feedvater effectiveness requires prediction of the tube heat transfer as well as feed spreading on the tube sheet. At present the codes have ienci in how tboubleey calculate. Our know$ edge oftSode defi$s wi+h such calcul tions becausEer an what in E$e codes.
is grea t
It is not clear that a research program is needed to sensure anything. Rather, the code should be changed. If a program to study the feedwater heat transfer in an OTSG is proposed, it should be clearly shown that there is a need for the calculational capability, a deficiency in our ability to calculate the phenomena and a method of implementing the results of the experimental study into the calculational tool in a physically meaningful way.
A comprehensive review of HRC's T/H research program should begin with a review of needs and capabilities. Many of us could put together something based on our experiences over the past few years.
It might help, however, to first have NRR and RES tell us what they l
think. Certain studies underway at INEL under Wilson are addressing l
such questions as part of establishing uncertainties in code l
predictions of peak clad temperature following a LOCA. With this start, one could move into trenstents, SBLOCAs and other events.
Wilson's work on the LBLOCA has shown that the downcomer and plena are areas of doubt. A number of studies of downcomers have been carried out yet a clear statement of where we are at cannot be found.
Does more research have to be done? With 2D/3D data soon to be available, we may well know enough to stop. The codes do not calculate l
condensation very well. Here we need to take a look and see whether l
vhet they do is good enough for our needs,
- e. g.
waterhammer, steamline overfill etc..
Operator training requires the use of simulators. NRC issued a reg.
guide on how well they predict the plant behavior. Here we need to assess how well the simulators are doing and what, if anything, needs to be done. In this area, EPRI's work under Bill Sun may be helpful.
The codes use two fluid modeling which requires modeling of interfacial transport processes. At present these processes are modeled relatively crudely. The question is whether or not the modeling is good enough. The codes do not havu counter current stratified flow modele in the hot leg forring them to use models that are incorrect but yield reasonable re sults. Should this be s; source of concern? These and other similar questions need to be addressed once and for all.
I ' W Gl' 8708280194 870712 PDR ACRS 1
CT-1895 PDR htVM b_
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With the shift away from the LOCA, the T/H needs must shift to fore j
day to day questions like ther e frequently raised by Carl and Jesse.
Has RES seen the light or are they still avoiding the real world?
4 In my opinion the ACRS could do a real service to NRC by asking for a written description of the regulatory need, a translation of the regulatory need into a reason for needed research by showing that some element of our modeling capability is missing, a research plan and a description of how the results of the research will be used to satisfy the reguletory need.
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