ML20211G200
| ML20211G200 | |
| Person / Time | |
|---|---|
| Issue date: | 10/02/1986 |
| From: | Lee T NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Silberberg M NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| Shared Package | |
| ML20211F389 | List:
|
| References | |
| FOIA-87-8 NUDOCS 8702250311 | |
| Download: ML20211G200 (9) | |
Text
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OCT 0 21995 MEMORANDUM FOR:
M. Silberberg, Chief Accident Evaluation Branch THROUGH:
R. Meyer, Section Leader Accident Phenomenology Section, AEB FROM:
T. Lee Accident Phenomenology Section, AEB
SUBJECT:
DIRECT CONTAINMENT HEATING RESEARCH REVIEW PANEL MEETING Enclosed please find the minutes of the subject meeting that was held on August 13, 1986 at Sandia National Laboratories in Albuquerque, NM.
T. Lee Accident Phenomenology Section, AEB
Enclosure:
As stated cc:
R. Meyer T. Speis J. Mitchell T. Theofanous M. Cunningham M. Corradini B. Morris B. Spencer C. Kelber T. Ginsberg D. Ross D. Powers F. Eltawila W. Tarbell F. Coffman K. Bergeron Z. Rosztoczy J. Walker distribution:
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- t' MINUTES OF THE DCH RESEARCH REVIEW PANEL MEETING The first meeting of the Direct Containment Heating (DCH) Research Review Panel was held on August 13, 1986 at Sandia National Laboratories (SNL) in Albuquerque, New Mexico.
Purposes of the meeting were:
1.
To present the DCH-1 test results to the members, 2.
To discuss the DCH-2 test and the DCH Standard Problem exercise.
3.
To identify features needed in a DCH analysis tool, and 4.
To discuss comments received during the program review meeting on April 22, 1986.
Participants in the meeting are listed in Enclosure I while the agenda cf the meeting is provided in Enclosure 2.
Following a brief opening statement, Bill Tarbell of SNL presented results of the DCH-1 test. There was no surprise in the results of the DCH-1 test except that the amount of aerosols generated exceeded previous observations from SPIT tests.
Preliminary estimation of the amount of aerosols are 5-10!; of the ejected materials as compared with 1-5% in SPIT tests. A draft report of the DCH-1 test is attached (Enclosure 4).
M. Corradini, K. Bergeron, and T. Ginsberg each presented the results of their test calculations. All were in good agreement with the test results although they are all post-test calculations and, as such, do not provide true measure of these codes' predictive capabilities.
Each analyst had to make certain assumption (s) regarding the mean flight paths, or the average airborne time, for the dispersing debris particles.
It goes without saying that this quantity varies from one facility to another; a value calibrated on one facility is not likely to be applicable to another.
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2 Specifications of the DCH-2 test that will be adopted as an DCH standard problem were proposed and modified to include comments received.
M. Pilch will 1
send out specifications to those who wish to participate within a week.
Results of the double-blind calculation are due before the day of the test to Tim Lee at USNRC.
Any difference in the actual test conditions from those specified will be conveyed to the participants via telephone immediately following the test for re-calculation.
Re-calculated results will be due within a week during which test data will be embargoed. On the test schedule, W. Tarbell advised that the DCH-2 test could be delayed until after the Water Reactor Safety Information Meeting because of the safety-review mandated by SNL's internal procedure. The projected delay appeared excessive even considering that the review may take about a month.
SNL was requested to explore the possibility of proceeding with the DCH-2 test preparation in parallel with the safety review. SNL promised to expedite.
I stressed the desirability of conducting DCH-2 before the 14th Water Reactor Safety Information Meeting and present the results in the meeting.
There was no disagreement among the panel members that DCH-2 is needed to provide data for the base case. Which test among those in the test matrix (Enclosure 3) should be conducted next (DCH-3) was discussed.
B. Spencer of ANL reiterated his belief that a higher temperature l
generated by iron-aluminum thermite is the contributing factor for high aerosol generation and urged that the corium test in the Surtsey test matrix be conducted next.
SNL is planning to conduct a calorimetric test to settle the l
controversy on the melt temperature.
The corium test in the Surtsey facility has to wait because SNL's plan to use induction heating, instead of corium thermite, to produce molten corium at an elevated pressure has never been The attempted before; some lead time is needed to develop this new technology.
use of induction heating would enable us to produce a melt that contains metallic Zr and Fe. This will resolve the controversy with respect to prototypicality of the melt simulants once for all.
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3 T. Lee suggested that a test with additional structures outside the reactor cavity be considered as DCH-3, but the panel could not come up with a specific suggestion as to what structures should be included. There was no other comment on the Surtsey test matrix.
4 The discussion of analytical modeling was postponed until after the lunch and the site visit because the meeting was falling behind its schedule.
T. Lee presented a list of features that are likely to be needed in the analysis of DCH (Enclosure 5) and solicited comments from the panel members.
Two subjects were discussed extensively; hierarchy of chemical reactions and the lumped parameter code versus the three-dimensional, finite difference code.
i T. Lee pointed out that the CONTAIN code has a provision that chooses certain chemical reactions over others for a given condition.
E.g., in the presence of oxygen and steam, metals will react with oxygen preferentially.
D. Powers pointed out thatthis provision is not desirable because it could 4
calculate incorrect partial pressures that will affect aerosol generations.
No existing computer code has an acceptable model that mechanistically calculates core debris dispersion and the effect of structures on the debris dispersal. The majority of the panel members seem to believe that a 3-D, finite difference code may be needed to analyze transport and mixing of debris particles in the containment atmosphere.
T. Lee pointed out that there are several such codes available to us and the one we think is closest to such application is COBRA-NC. There is a possibility that such a model can be incorporated into the COBRA-NC code with a minimal cost.
K. Bergeron disagreed; he thinks a new code should be developed if we decided to go with a 3-D, finite difference code.
He estimated that it would be a multi-million dollar undertaking and requested to be given an opportunity to bid on it.
T. Lee has a strong reservation on K. Bergeron's assessment.
Comments received during the April 22 meeting were classified in a dozen categories to combine repetitions (Enclosure 6). Only the most important subject, the effect of structure, was discussed extensively because the meeting i
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4 fell behind the schedule a couple of hours.
SNL and BNL were requested to provide their responses to these comments in writing.
We will prepare a formal response to those who provided the comments when input from SNL and BNL is received.
At this time, M. Corradini indicated that he had to leave soon and requested time to present results of his hand calculations on the Surry plant.
M. Corradini volunteered to perform calculations of average velocities and associated Kutateladze numbers as requested by T. Theofanous, who could not attend the meeting because of a schedule conflict. As expected, Corradini had to make an assumption regarding heat transfer from hot debris to the mixture of steam and gas. He suggested that, as a compromise, we should consider performing such calculations for three NUREG-1150 plants; Zion, Surry and Sequoyah.
D. Powers questioned the usefulness of such exercises, especially the validity of the Kutateladze number, based on an average flow velocity, as the entrainment criterion in a complicated three-dimensional flow field that is highly turbulent.
T. Lee promised to evaluate both suggestions carefully, but observed that such a task appeared more appropriate for a Technical Assistant program in NRR.
t K. Bergeron presented the results of recent CONTAIN calculations that showed tremendous hydrogen generation due to metal-steam reactions in and around the reactor cavity.
Since hydrogen can readily mix in the containment atmosphere regardless of debris transport, Bergeron wondered whether the effect of structures on DCH has been over-emphasized.
T. Ginsberg indicated that BNL's calculations also showed that metals in dispersing debris could be completely oxidized in metal-steam reactions before the debris gets out of the reactor cavity region.
Even if this finding can be substantiated by test data, we still have to confront the question of the effect of structures on core debris dispersal because of the huge thermal energy contained in the core melt.
On the effect of the structure, there was no disagreement among the panel members that a small scale test facility has built-in biases against the debris l
dispersion and containment heating, and that it is not obvious how these biases
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5 can be compensated for.
Integrated tests, therefore, would not be meaningful.
In any event, the panel agreed that a mock-up of the reactor containment, as suggested by IDCOR, that includes not only major structure and equipment, but also piping and grating, is not feasible even at a reduced scale.
It appears that the only viable approach to investigate the effect of structures on DCH is to develop analytical models from the test data to be incorporated in a containment code for analysis of DCH in full scale commercial plants.
The panel members, however, could not recommend what specific configuration (s) should be investigated in the tests.
K. Bergeron was asked what analytical models he would want, as an analyst, to be included in the CONTAIN code so that he could analyze the core debris transport.
Bergeron said he cannot answer this question at the moment because he still does not know what are the significant physical processes that must be considered in such an analysis. He is hoping that small scale tests on-going at BNL could provide clues to identify suen physical processes.
M. Pilch suggested that, as the first attempt, we may want to consider simulating the missile shield above the RPV that can deflect the dispersing flow through the annular gap around the RPV.
This test is expected to provide a data base for modeling re-entrainment of debris particles intercepted by a concrete surface.
BNL agreed to conduct scoping test to identify if any other configuration should be tested.
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. to Trip Report, T. Lee List of Participants DCH Research Review Panel Meeting, 8-13-86 Name Affiliation Telephone No.
William Tarbell SNL FTS 846-0473 Ted Ginsberg BNL FTS 666-2620 Bruce Spencer ANL FTS 972-4754 Ken Bergeron SNL FTS 844-2507 Jack Walker SNL FTS 844-2876 Michael Corradini Univ. of WI (608) 263-2196 Dana A. Powers SNL FTS 844-4392 Robert Nichols K-tech Tim M. Lee NRC/RES FTS 443-7616 Lichung T. Pong SNL FTS 846-4876 Ken E. Washington SNL FTS 846-0136 Commercial numbers for SNL and for NRC are identical as the FTS numbers. Area codes are (505) for SNL and (301) for NRC/RES.
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. to Trip Report, T. Lee fcenda for DCH Research Review Pcnel Meeting Landia National Laboratory, Albuquerque, NM Bldg. 825, Technology Transfer Center 1.'ednesday, August 13, 1986 T. Lee 8:30 am Opening Remarks 8:25 am Results of DCH-1 Test W. Tarbell 1
9:15 am DCh Test Analyses M. Corradin; K. Bergeron T. Ginsberg M. Pilch 10:00 am BREAK 10:15 am Projection for DCH-2 Test and Specification for DCH Standard Problem M. Pilch 11:00 Physical Models Needed in DCH Analysis Codes All Participu.ts 12:00 LUNCH T
1:00 Site Inspection of SURTSEY Facility W. Tarbell M. Pilch 2:15 Review of Comments Received During DCH Program Review Meeting, 4/22/86 T. Lee All Participants 5:00 ADJ0VRt i
DCH TEST MATRIX SURTSEY DIRECT HEATING FACILITY Test Characteristic
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1 Small mass (20 kg) 2 Large mass (80 kg) 3 Surry cavity 4
In-containment structures 5
Defined flow paths i
Inert atmosphere 7
- Air, steam,
& H2 I
Water sprays j~
$. 3 Corium melt N
Water-filled cavity 1-Shallow ' water pool
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