ML19263C444
| ML19263C444 | |
| Person / Time | |
|---|---|
| Site: | Millstone, Hatch, Monticello, Dresden, Peach Bottom, Browns Ferry, Fermi, Oyster Creek, Hope Creek, Cooper, Pilgrim, Brunswick, Vermont Yankee, Duane Arnold, Quad Cities, FitzPatrick |
| Issue date: | 01/31/1979 |
| From: | Charemagne Grimes Office of Nuclear Reactor Regulation |
| To: | Post R ARIZONA, UNIV. OF, TUCSON, AZ |
| References | |
| TASK-06-02.A, TASK-RR NUDOCS 7902220257 | |
| Download: ML19263C444 (2) | |
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NUCLEAR REGULA10RY COMMISSION W ASHINGTON. D. C. 20555 g ~,
f JAN 311979 Dr. Roy G. Post, Editor Nuclear Technology c/o University of Arizona Department of Nuclear Engineering Tucson, Arizona 85721
Dear Dr. Post:
RE: MS#3360 In response to your request of January 11, 1979, I have completed my review of the paper entitled " Vent Clearing During a Simulated Loss-of-Coolant Accident in a Mark I Boiling-Water-Reactor Pressure-Suppression System," by Drs. John Pitts and Edward McCauley of the Lawrence Livermore Laboratory (LLL).
Based on the coments dis-cussed below, I recomend that the paper be accepted for publication.
with major revisions.
The subject of this paper is a discussion of the measurements and phenomena observed in a 1/5-scale simulation of a Mark I containment suppressica chamber (torus) during the short-term, " pool swell" phase of a LOCA. Two of the conclusions drawn by the authors are either inaccurate, or have not been clearly stated:
1.
The authors conclude that the test results are independent of the gas used, so long as it is an ideal gas.
However, the scaling relationships for pool swell dictate that the specific heat ratio of the gas used must be essentially the same as air or the vent flow rate will become invariant.
This conclusion was previously reported by Ain Sonin of MIT and Ivan Catton of UCLA (CONF-770708, SunValley, Idaho, August 1977).
2.
The authors conclude that scaling enthalpy flux in the vent system is unimportant. However, this conclusion is relative to the degree of accuracy desired in the measured loads on the torus.
In a previous report, LLL concluded that removal of the vent line orifices, which are used to scale enthalpy flux, could increase the net upward pressure load on the 790 2220 A59
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Dr. Roy G. Pos-torus by approximately 30"..
This level of uncertainty in the load is significant when you consider that 22 of the 25 Mark I plants are built and are operating.
The ultimate conclusion of the paper is that quantitative values obtained from the test facility can be applied to the full-scale plants using the established scaling laws.
However, the bulk of the paper speaks to the relationship between the measurements and the phenomena, but does not address the accuracy or uncertainty of the measurements.
Since the pool swell loads are a substantial part of the LOCA loads on the torus, the accuracy of the measure-ments is of greater significance to the issue of safety.
LLL is currently completing error and uncertainty analyses of the test results.
I believe that this discussion would significantly improve the paper.
Two other points discussed in the paper require clarification. The authors emphasize the vertical asymetry of the vent clearing process due to the location of the miter in t~ e downcomer.
However, they n
fail to note that their downcomer design is not typical for all plants, nor do they discuss the relative significance of the asym-metric clearing. Also, the authors note the presence of strong instabilities at the gas-water interface during the clearing process, but they do not identify the source of the instabilities or their influe1ce on the load magnitudes.
I believe that once these comments are accommodated, this paper would provide a good synopsis of the pool swell event in a Mark I suppression chamber.
If I can be of any further assistance, or should you have any questions, please do not hesitate to contact me.
Sincerely, Chris Grimes Plant Systems Branch Division of Operating Reactors
.