ML20052D744
| ML20052D744 | |
| Person / Time | |
|---|---|
| Issue date: | 12/07/1981 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-1925, NUDOCS 8205070167 | |
| Download: ML20052D744 (11) | |
Text
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ACRS REACTOR FUEL SUBCOMMITTEE c
MEETING MINUTES NOVEMBER 18, 1981 Yg
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Purpose:
The purpose of the meeting was to review the fuel research(program for the ACRS Report to Congress on the FY83 Research budget.
Notice of the meeting was published in the Federal Register on October 30, 1981.
Attendees:
Principal attendees of the meeting included:
ACRS NRC - RES Sandia Laboratory P. Shewmon M. Silberberg J. Ravard J. Ebarsole R. Van Houten R. Lipinski W. Mathis R. Wright A. Solomon - Consultant G. Morino P. Boehnert - DFE G. Knighton M. Tokar H. Scott Meeting Highlights, Agreements and Requests 1.
The meeting was convened at 8:30 a.m.
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l 2.
Dr. M. Silberberg (Chief, Fuel Behavior Research Branch), provided an l
overview of the Severe Fuel Damage (SFD) Program. The SFD program objective l
is to provide a data base and analytical methodology for understanding and predicting core behavior under severe accident sequence conditions.
He said
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the results of the SFD program would be applied in three areas; (1) accident management to terminate an accident in-vessel at different points in the l
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Reactor Fuel iltg. 11/23/P1 accident sequence; (2) improvement of risk assessment and risk reduction; and. (3) aiding the severe accident rule making.
In response to a question from Dr. Shewmon, Dr. Silberberg replied that the " reason-d-etre" of the pros un rests more on items 1 and 2 than on item 3.
Dr. Silberberg also noted that the risk assessment and risk reduction effort would address the "real
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world of core damage" and ignore the WASH-1400 assumption of core melt at 2200 F.
Dr. Shewmen also asked how fission product release was being evaluated in this program.
RES responded that this is being handled by separate effects measurements on irradiated fuel plus work on modeling of source term behavior.
The main elements of the SFD Program were highlighted.
There are five program elements involved. These include: (1) Integral (multi-effect) in-pile test in PBF, ESSOR, and possibly NRU; (2) pheonomenological separate-effects experiments which include deoris formation and relocation experiments in the Annular Core Research Reactor (ACRR), and full length 64-rod bundle clad ballooning, bursting, and coolability experiments at Oak Ridge, (plus additional laboratory experiments); (3) TMI-2 core exam-ination; (4) analytical model development.wnich includes the integral "
Severe Core Damage Analysis Package code (SCDAp); and (5) the study of core melt progression to vessel failure.
In response to question from Mr. Boehnert on the status of the Bil-2 core examination,RES responded that preparations for the core exam are now
Reactor Fuel Mtg. 11/23/81 unde say,and it is expected that in 1983 an optical instrument will be inserted through the v'essel head to check the core condition.
Vessel head removal is scheduled for some time in 1984. RES also noted that NRC is not involved in the financial aspects of the TMI 2 clean-up.
Dr. Silberberg highlighted the changes in the fuels research progrom direction for the FY 82-8'3.
He noted that the PBF OPTRAN tests will be completed in FY82, and that the clad ballooning testing in U.TJ will also be completed in FY82.
Programs to be continuing through FY83 include the laboratory PCI experiments at Argonne, and the FRAP-T/FRAPCON/MATPRO code work. There are 4 tests planned for the PBF severe fuel damage test program and an accelerated testing program is planned at the ACRR.
Dr. Shewmon observed that RES has not extended much effort on evaluating the overall direction and goals of the SFD program.
RES responded that as experimental information becomes available, and with the present realities of budget constraints, they will continually be reassessing the program's directions and goals.
Dr. Shewmon also asked if RES has decided that the high-temperature ( >4000*F) Phase II PBF test are necessary.
RES responded
- hat this is still under discussion. One of their concerns in the evaluation of the behavior of control rod absorber material.
FRG experiments nave shown that the material tends to splat all over fuel bundles at very high tempe ratures. Another associated question is the effect on recctor criticality as a result of the absorher redistribution.
i Reactor Fuel Mtg. 11/23/81 3.
Dr. R.' Van Houten (NRC-RES) provided an overview of the NRU test program including the results from the most recent materials defermation test.
He noted that since April of this year, there have been 4 tests in NRU:
one thermal hydraulic test, two material deformation tests (clad ballooning),
and one combination thermal hydraulic and material deformation test. The latest test was a material deformation test which was designed to produce elongated cladding bal.ooning. The test results did show elongated ballooning, however, the peak strains were much lower than was predicted by analysis which indicates that the presence of the nuclear fuel results in lower peak strains.
Heat transfer tests also show that that there was adequate cooling of the deformed bundle.
4.
Mr. R. Wright (NRC-RES) provided an overview of a discussion on the portion of the SFD program dealing with debris bed coolability.
He showed a matrix (Figure 1) that details what experiments are ne.eded to answer specific questions dealing with a severe accident that progresses from fuel debris through vessel failure.
In response to a question from Dr. Shewmon, Mr. Wright noted that the study of phenomena dealing with core melt prograssion to vessel failure is a low priority itea at the present time.
5.
Dr. R. Lipinski (Sandia Laboratories) discussed the issue of degraded core coolability for LUR's. highlighting the information needed to determine i
Reactor Fuel Mtg. 11/23/81 debris coolability.and what LWR debris characteristics need to be detenained.
Mr. Lipinski highlighted the results of recent bundle deformation tests by Hagen, et al at KfK, and the steam explosion tests at Sandia.
Commenting on the steem explosion results, Dr. Shewmon observed it-appears that RES is ignoring whether this information is relevent to a real reactor situation and thus, may be doing more harm than good to the overall safety program.
Dr. Lipinski discussed various models that attempt to predict debris coolability based on particles size.
He concluded that the particles must be several millimeters in diameter for coolability.
The several millimeter figure was quoted as a conservative assumption.
Dr. Lipinski noted that some of the perameters for which core cooling data is lacking in-includes such effects as; large bed thicknesses, particle size distributions, flow stratification, and high system pressure.
In summary, Dr. Lipinski said the largest uncertainty in predicting debris coolability is the con-figuration of the initial debris.
6.
Mr. J. Ravard (Sandia) discussed the planned separate effects experiments in ACRR designed to study core debris formation, relocation, and cool-ability.
Figures 2-3 show details of the ACRR reactor and planned 9-rod bundle i
test section. There are two series of experiments planned, the first series of eight to twelve experiments will study debris formation,while the second series consisting of eight experiments will study the coolability of debris quench formations.
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Reactor Fuel Mtg. 11/23/81 Mr. Ra'vard noted that the ACRR experiments will cost about a factor of ten less than similar type experiments that could be conducted in PBF.
In response to questions from Dr. Solomon, NRC said that there will be no attempt to study burn-up effects in these experiments, that parameter will studied at later tests planned in PBF.
In response to a question from Or Shewmon, NRC noted that planned out-of-pile cool-ability experiments will.l'ok at deep bed debris coolability.
These are o
needed because the maximum debris height possible in nCRR is only 50 centimeters.
7.
Mr. G. Knighton and Mr. M. Tokar responded to a Subcommittee question concerning NRR's critique of the planned RES severe fuel damage program.
Mr. Knight r.oted that since neitherNRR or RES has a clear understanding of just what the Severe Core Damage rule making will require, the test program has been made all encompassing.
He noted that NRC is expecting further guidance from the Commission on the rule making reqeire-ments.
He said he expects a program review in light of clarification of the rule requirements.
Mr. Tokar said NRR expects that the new rule will result in guidelines that go beyond the current core coolability criteria.
He also noted that he would not want to see the program tied too closely to the rule requirements i.e., the program should be able to generate information worthy of support on its own merits. Mr. Knighton 0
also noted that the program as currently outlined may not be entirely l
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s Reactor Fuel Mtg. 11/23/81 necessary when, agaiq clarification of the severe core damage rule requirements has been made.
In response to questions from Dr. Shewmon,
Mr. Knighton noted that NRR did rank certain elements of the program.
The ranking,in order of priority.is as follows; (1) TMI-2 Core Exam-
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ination/ Characterization; (2) Separate-Effects Tests (Ex-Reactor to the extent feasible); (3) Integral Tests (In-Reactor to the extent feasible);
(4) Analytical flodel Development (SCDAP); and (5) Research Products in the For.n of Analysis codes (such as SCDAP).
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The meeting was adjourned at 12:55 p.m.
NOTE: A transcript of the open portions of this meeting is available in the NRC Public Document Room, 1717 H Street N.W.,
Washington, D. C. or can be obtained at cost from Alderson Reporting, Inc., 400 Virginia Avenue i
S.W., Washington, D.C. 202/554-2345.
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L Input-Output Matria for,the Severe Fuel Damage Emperiment Program
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Clad Ballooning. Burst, and PBF-1, 2 ACRR I
Blockage ESSOR/NRU DECCA X
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X Lab 2.
Oxidation (Hydrogen)
PBF-1, 2 ACRR ESSOR/NRU DECCA X
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X Lab 3.
Fission Product Release PBF-1, 2 Lab and Attenuation ESSOR/NRu X
4 Fuel Debris Characterization PBF-1. 2 ACRR ESSOR/NRu X
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X 5.. Fuel Debris Relocation.
PDF-1, 2 ACRR Blockage ESSOR/NRu X
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Reflood Debris Character-P8F-1, 2 ACRR j
12atten ESSOR/NRU DECCA X
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LMF Lab I
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Rapid Steam Generation and PBF-2 ACRR Explosion LMF Lab X
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Damaged Bundle Coolablllty PBF-2 DECCA X
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Fuzi Debr1s Coolabi11ty PBF-2 ACRR t
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10 Post-Dry-Out Behavfor ACRR Lab X
- 11. Melt Progression PBF-2 ACRR LMF Lab X
- 12. Debris Characterf ration at P8F-2 ACRR Vissel Failure LMF X
[1)e data and models from these experiments are integrated into the SC3AP severe core damage code
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