ML20010H711
| ML20010H711 | |
| Person / Time | |
|---|---|
| Issue date: | 07/20/1981 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-MA-1876, NUDOCS 8109290179 | |
| Download: ML20010H711 (8) | |
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DN Sh/l8l DATE ISSUED:
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MINUTES JULY 20, 1981
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ACRS SUBCOMMITTEE ON REACTOR FUELS g EIIEl WASHINGTON, D.C.
JULY 7, 1981 PURPOSE:
Tc discuss research programs sponsored by the Fuel Behavior Research Branch.
PRINCIPAL ATTENDEES:
P. Shewmon, Chairman M. Silberberg, RES H. Etherington, Member G. Marino, RES
. p \\ ' p l p"' /'
u W. Mathis, Member R. Wright, RES A. Strasser, Consultant P. Mcdonald, EG&G Q'
D. E. Bessette, ACRS Staff P. Pickard, Sandia g /, @p4 A'q)
R. Coats, Sandia 3
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R. Van Houton, RES
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(a J. Scott, RES 19
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R. Chapman, ORNL y$
C. Allison, EG&G y
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No written or oral comments were received from members of the pub i i
Attached is the meeting agenda and a list of documents considered by the Subcommittee.
Fuel Testing Task Force Report M. Silberberg, G. Marino, and R. Wright summarized the report of the Severe Fuel Damage Testing Task Force. The report was the result of three months of effort, which started in late March 1981.
The purpose was to define informa-tion needs and evaluate how the planned severe fuel damage tests will respond to these needs. A draft of the report will be issued July 10, 1981.
It will be subjected to peer review for about one month.
The severe fuel damage testing program is expected to provide information on:
i understanding the conditions of the core; accident signatures, and responses of instruments; developing a code that models core degradation processes; fission product release rates; and hydrogen production.
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.CT-1876 PDR
Reactor Fuels Mtg July 7, 1981
.G. Marino summarized the damage regimes that result from overheating of the j
core. Damage' regime 1 extends to 1700 F.
It includes possible clad collapse or ballooning and possible release of the gap activity, but has minimal conse-quences.
Damage regime 2 extends to about 2500 F.
Clad oxidation starts to become signi ficant:Zi rcaloy-UO reaction begins. Clad rupture is likely. Regimes 1 2
and 2 have been well-studied except for determining the extent of clad balloon-ing and its effect on core cooling.
Present evidence indicates that, if anything, cooling is enhanced.
Mr. Mathis and Dr. Shewmon noted that while se ruel damage information is useful, it would act be likely to influence operator actions during the course
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of an accident.
-Damage regime 3 extends to about 3400 F.
The cladding may fragment upon cooling. Zircaloy-UO reaction may be significant.
2 Damage regime 4 extends to about 3600 F, the melting point of Zircaloy.
There may be a significant amount of liquefied fuel, i.e., reduction of the U0 by Zirconium to lower its melting point. Regimes 3 and 4 will be studied 2
in the currently planned ?BF tests.
A severe core damage code, SCDAPs will be developed. Dr. Shewman asked whether it was the purview of the FBRB to deter-mine wnether the melt will be at the liquidus temperature or above it, since this is crucial to whether a steam explosion is possible. Mr. Silberberg indicated that this question will te addressed.
Reactor Fuels Mtg July 7, 1981 The in-pile' work will be supplemental by phenomenological separace effects experiments. ESSOR, and possibly NRU, will perfom severe fuel damage tests on a larger scale than PBF. The U.S. cost-share for ESSOR is about 10%.
Although there may be a large number of possible accident sequences, the
-condition of the core will be largely influenced by the particular damage regime reached, so it is not necessarily a hopeless task to perfom experi-ments that will characterize fuel behvior over a range of accident sequences.
It was indicated that to date minimal work has been done on attack of the vessel by the melt.
It was also indicated that a $1M a year program is planned in studying in-vessel debris coolability. Mr. Sf1berberg indicated that the PBF SFD tests and the TMI-2 core exam are the highest priority items within the SFD program. Broad participation in the programs should be sought where possible including foreign countrie,. The source tem infomation to be generated is an important element of the SFD program.
PBF PROGRAM P. Mcdonald.(EG&G) discussed the PBF SFD program. Test train fabrication is underway. Five tests are planned with two heating rates (1/2 C/s and 6 C/s)
L and two coolowon modes (quench and slow cool). A 32-rod bundle will be used.
lne PBF in-pile tube is 8" diameter. Bundle power and steaming rate will be controlled to obtain the desired heat up rate. Attention will be given to 0
monitoring fission preduct release.
Peak temperaturc would be about 3500 F.
0 Phase II testing would be to about. 5000 F, and would use the current in-pile tube and possible also an enlarged in-pile tube for Phase II-B tests. Modiff-cation to PBF, should it occur, would be in 1984 or 1985.
y Reactor Fuels Mtg July 7,1981 SANDIA PROGRAMS ON DEBRIS FORMATION AND C00 LABILITY P. Pickard and R. Coats (Sandia) described SFD experiments planned by Sandia.
The objectives are similar to the PBF program. The size would be 9 rods.
Visual observation; would be included. The FY 1983 funding is $1M.
Debris coolability will be studied using LMFBR work as a basis.
Dr. Shewmon inquired as to what distribution of particle sizes would be used for the debris coolability studies. Mr. Coats indicated that they would be from micron sizes up to 100 f m.
Most of the infomation on which the information of particle size is based is from power burst experiments.
Dr. Shewmon ques-tioned whether those particle sizes have any relevance.
NRU R. Van Houton (RES) discussed the NRU program. A series of about 30 themal hydraulic tests (T-H) were run. NRU utilizes a 32-rod bundle. The heating 0
rate was 8 C/s to peak temperatures about 2000 F.
The tests were completed in October 1980. The first clad ballooning test was run, and the second is scheduled for July 1981. The U.K. has contributed $2M toward the NRU clad ballooning program. Japan, Germany, and EPRI may also be interested in contri-buting funds.
Conclusions from the T-H tests are that peak clad temperatures are comparable to FLECHT data. Quench, however, occurs more rapidly in nuclear heated rods than on electrically heated rods.
DLE-RAMP R. Van Houton described NRC participation in the Demo-Ramp program. This program cost $200K. The facility is the Studsvik R-2 reactor. The purpose is to ir.vestigate the threshold for PCI failure durirjg power ramps.
w Reactor Fuels Mtg-July 7, 1981 v.
ESSOR R. Van Houton gave the status of the ESSOR program. European participants have cmnmitted $60M. The U.S. share is about $1.5M per year.
DECCA R. Chapman (ORNL) gave the status of the MRBT and the proposed DECCA programs.
'The DECCA program would utilize full length electrically heated bundles.
It would investigate ballooning and bundle +nermal hydraulics.
Construction and fabrication would occur in 1984.
Dr. Shewmon asked what DECCA would provide-that won't be obtained from NRU.
The answer.was that DECCA w6uld investigate ballooning at elevated system pressures.
Dr. Shewmon noted that under such conditions oxidation would limit ballooning.
SCDAP C. Allison (EG8G) discussed the SCDAP SFD code.
The code will model a single bundle. An initial version of the code will be ready by June 1982.
It will consist primarily of currently existing models.
It will emphasize fission product release rates, hydrogen generation, and debris fonnation.
FRAP STATUS G. Marino presented a status summary of FRAP. FRAPCON-II is the final version of the steady-state code; FRAP T-6 is the final version of the transient code. FRAP will be on inaintenance status in 1983. The original purpose for I
FRAP-T was modeling a large break LOCA.
It was indicated that code users must read the code assessment documents in order to know the limitations of the code.
s.
Reactor. Fuels Mtg July 7,1981 HALDEN PROGRAM H. Scott (RES) discussed NRC participation in the Halden project. Tne purpose
-has been to gather information to support licensing needs relating to Appendix K requirements. One topic that has been studied is gap and pellet conductivity
'in order to' model stored energy. The Halden participation has fulfilled the program objectives and work will be terminated by FY 1983.
APPLICATION OF P~ SEARCH RESULTS TO REVISION TO APPENDI Q G.. Marino discussed this subject.- Research has showed the decay heat curve
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should be 0.95 times the 1973 ANS rather thaa the 1.2 times 1973 ANS that
= licensing uses. Clad o.vidation modeling should use the Carthcart-Pawel model rather than Baker-Just. Oxidation criteria should be based on Kassner-Chung rather than the 0.17 times the minimum wall thickness that is currently used.
Research believes these matters are resolved and should be implemented by licensing. Mr. Marino indicated that clad ballooning is not resolved and further work is needed.
Dr. Shewmon noted that the clad ballooning work by the FBRB is focusing too much on just studying clad ballooning and not enough on the other part of the question, which is thermal hydraulict and coolability.
Mr. Marino indicated that fuel stored energy and gap conductance are well-characterized and no further work is needed. This infonnation shows' stored energy is currently overestimated by about 10%. The DNB criteria has been shown to be excremely conservat<ve.
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ACRS REACTOR FUEL SUBCOMMITTEE MEETING
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~~ JULY 7, 1981 WASHINGTON, DC
/
- Tentative Schedule of Presentations -
Presentation Actual
- Time Time 5 min 8:30 am I.
INTRODUCTION P. Shewmon - Chairman 17.
RES FUEL BEHAVIOR PR3 GRAM PRESENTATION 60 min 8:40 am
. A.-
Fuel Testing Task Force Report Silberberg - RES Wright -
- RES
'Marino
- RES BREAK 10 min 10:40 cm 25 min 10:50'>am B.
PBF --Severe Fuel Damage Tests MacDonald - EG&G C
Debris Formation, Relocation & Coolability 20 min 11:40 am Pickard/ Coats - Sandia LUNCH 60 min 12:20-1:20 pm 30 min 1:20 pm D.
ESSOR-NRU-PCI-Programs Van-Houten - RES 20 min 2:20 pm E.
Severe Core Damage Analysis Package (SCDAP)
Picard - Sandia 15 min 3:00 pm
-F.
FRAP-T Code Status Marino - RES BREAK 10 min 3:30 pm 15 min 3:40 pm G.
Halden Program Scott - RES 20 min 4:lC pm H.
Application of Research Results to Revision of Appendix K Marino - RES I
m 25 min 4:50 pm I.
Multirod Burst Test Program - Long Bundle Tests Chapman - 09NL i
6:00 pm Li !. DISCUSSION AND ADJOURN
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-(Time has been allowed in excess in Presentation Time for Subco.nmittee questions.
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LIST OF DOCUMENTS 1.
NRC Fuel Testing Task Force Report 10 slides 2.
State of Knowledge and Information Needs on Severe Fuel Damage 10 slides 3.. How NRC. Programs will meet Information Needs 6 slides
~4.
PBF Severe Fuel Damage. Test Series 35 slides
- 5. 4 Debris Formation Relocation, and Coolability Programs at 26 slides Sandia 6.
NRC, ESSOR, Studsvik Programs 14 slides 7.
DECCA Program 22 slides 8.
SCDAP Code Development 9 slides 9.
FRAP-Status 8 slides
- 10. Halden Program.
23 slides
- 11. Application of P,etearch Results to Licensing 4 slides
- 12. Draft Report of the NRC Fuel Testing Task Force 4
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