ML20076E999

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Provides Preliminary Comparisons Between Steam Condensation Test Performed in Surtsey Facility on 931119 & Contain Calculations
ML20076E999
Person / Time
Site: 05200002
Issue date: 01/07/1994
From: Stamps D
SANDIA NATIONAL LABORATORIES
To: Malliakos A
NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
Shared Package
ML20076E998 List:
References
NUDOCS 9405100203
Download: ML20076E999 (2)


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SandiaNationalLaboratories i Albuquerque, New Mexico 87185 I j

Dr. Asimios Malliakos January 7,1994 Accident Evaluation Branch Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission MS: NUN-344 Washington, DC 20555

Dear Dr. Malliakos:

As you requested during our discussion over the phone today, I am providing preliminary compar-isons between the steam condensation test performed in the Sunsey facility on November 19, 1993 and CONTAIN calcuktions. The main conclusion is that the rate of steam condensation occurs on the order of minutes, not seconds, and that the predictions were in reasonable agree-ment with the data.

I l The atmosphere was well mixed in the experiment: the initial concentrations by volume percent l were 76.05% steam,20.65% ak (4.32% oxygen), and 3.30% he'ium. The initial temperature and l pressure were 419 K and 0.475 MPa, respectively. This mixture was subjected to a water spray for l 16.3 minutes. The spray flow rate was 30.5 ppm. spray water temperature was 321 K, and drop mass median diameter was 1080 microns. Details of the experiment are given in the December 13,1993 letter from T. Blanchat to you. The steam concentration decreased from approximately 76% to 45% in 16 minutes. The highest concen:ntion of steam in which a detonation was observed in a hydrogen-air-steam mixture was approximately 39% in the Heated Detonation Tube at SNL. Tnis detonation was initiated with 100 grams of high explosive.

A CONTAIN calculation was also performed prior to the Surtsey steam condensation experiment. 3 The conditions for the code calculations were somewhat different than those in the experiment: r.

spray flow rate of 23.3 gpm was assumed instead of 30.5 gpm, hydrogen was used instead of helium, and the initial conditions were not exactly the same. In spite of the differenet.s, however, significant changes in the results would not be anticipated if the actual Surtsey conditions were used.The predicted average rate of pressure drop due to steam condensation was approximately 15% greater than the experimentally measured rate.

The conditions in the Surtsey facility are simihtr to those in the CE System 80+ containment. This was discussed in the October 1,1993 letter from T. Blanchat to you. CONTAIN calculations indi-cate the water spray drops attain thermal equilibrium relatively quickly in the Sunsey facility.

This would also be expected in the CE System 80+. As such. the spray mass flux becomes the important parameter p .erning the rate of steam condensation. The spray mass flux in the Surtsey l

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steam condensation experiment was 0.181 kg/m2 s compared to 0.138 kgim2s for the CE System 80+ when only one of the twc sprays systems work.

Sincerely, Douglas Stamps Containment Modeling Depar* ment,6429  :

Copy to:

1 NRC/NRR M. Snodderly MS 1137 T. Blanchat (6422)

MS 0739 K. E. Washington (6429)

MS 0739 D. W. Stamps (6429) i l

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