ML20059F271
| ML20059F271 | |
| Person / Time | |
|---|---|
| Issue date: | 12/21/1993 |
| From: | Tayolr J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | |
| References | |
| SECY-93-350, NUDOCS 9401130247 | |
| Download: ML20059F271 (10) | |
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POLICY ISSUE December 21, 1993 SECY-93-350 EQB:
The Commissioners FROM:
James M. Taylor Executive Director for Operations l
SUBJECT:
STATUS OF NRC RESEARCH CONDUCTED BY THE RUSSIAN RESEARCH CENTER (1.V. KURCHAT0V INSTITUTE) AND PROPOSED CONTINUATION OF THESE ARRANGEMENTS
- PURPOSE:
To inform the Commission of the progress made on research sponsored by the NRC at the Russian Research Center (the I.V. Kurchatov Institute) in the area of severe accident research and irradiation and annealing of U.S. reactor pressure vessel samples in the Novovoronezh-5 reactor. Also, to inform the Commission of the staff's plan to continue these arrangements provided that research results continue to be of value to the NRC and that measurable progress is being made. We will inform the Commission annually of these issues.
DISCUSSION:
In SECY-91-375, " Proposed Arrangement with the I.V. Kurchatov Institute for Atomic Energy of the U.S.S.R. on Severe Accident Experiments," and in SECY 015, " Addendum to SECY-91-375," the staff provided detailed descriptions of the Russian programs and recommended to the Commission that research cooperation between the NRC and the Russian Research Center was of interest to the NRC.
The Commission endorsed the staff recommendation.
In SECY-92-419,
" Status of NRC Research Arrangements with the Russian Research Center (1.V.
Kurchatov Institute) and the Russian Academy of Sciences, and Proposed NOTE:
TO BE MADE PUBLICLY AVAILABLE IN 10. WORKING DAYS FROM THE DATE OF THIS PAPER
Contact:
Themis Speis, RES 492-3710 incana g6 9401130247 931221
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Continuation of these Arrangements," the staff reported that the objectives of the hydrogen combustion research were to investigate, both experimentally and theoretically, the behavior of hydrogen-air mixtures and to evtluate the effect of scale on hot turbulent jet detonation initiation concitions.
Note that in SECY-92-419, two other areas of research cooperaitei were also identified, namely the phenomena involved in in-vessel melt retention during a severe accident and the validation of NRC's core-concrete interaction code C0RCON-MOD 3.
The primary objective of the in-vessel melt retentien research is to ascertain experimentally (using the RASPLAV facility) the conditions under which a degraded / molten core can be retained in the vessel.
Because this issue is of high interest to many countries with nuclear power programs, NRC recommended that the RASPLAV program become an international cooperative project under OECD/CSNI sponsorship. Two CSNI special meetings were held in Paris, France in April and July 1993, to discuss the RASPLAV project.
There was general consensus regarding the need for such a project. Accordingly, this task will be dropped from the NRC/ Russian Research Center agreement once the OECD consortium agreement is finalized.
A final decision will be made in March 1994.
The primary objective of the CORCON-MOD 3 validation exercise is to gain a wider users' perspective on the code applicability and reliability.
The Russian Academy of Sciences prepared a draft report entitled " Assessment of CORCON-MOD 3 Code." We have reviewed the report and provided comments to the Russians. The report did not include all the assessment calculations called for in Addendum 3 of the Agreement.
Once we receive all the calculations called for in Addendum 3, we will issue a NUREG report summarizing the Russian work done on this code. This will complete the work in this area. The following summarizes recently completed and newly proposed research programs at the Kurchatov Institute and the Russian Academy of Sciences.
Hydroaen Behavior:
Recently, we received a report, " Experimental Study on the Combustion Behavior of Hydrogen-Air Mixtures with Turbulent Jet Ignition at Large Scale," July 1993, prepared by scientists at the Russian Research Center describing their work to develop a criterion for conditions defining the onset of detonation due to turbulent jet ignition.
This research report, which the staff subsequently issued as NUREG/CR-6072, includes the results of testing carried out in the X0PER facility, which is a large semi-cerfir.ed volume (approximately 50 m') designed to investigate conditions of explosion initiation and propagation in gaseous fuel-air mixtures.
In addition to describing their own experimental work, which involved 29 tests with hydrogen-air mixtures, the authors have also compared their results with existing data generated world wide, at different scales, and concluded that the minimum conditions for turbulent jet initiation of detonations can be correlated with the jet diameter and the mixture cell size, which is characteristic of the mixture composition.
In the K0PER facility the minimum requirements for producing a detonation were hydrogen concentrations of 20-25% in the large volume and a jet orifice diameter of 0.1 to 0.2 meters.
This work also addresses ongoing efforts to
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develop a generalized methodology for predicting the possibility of detonations due to both turbulent jet initiation and deflagration to detonation transition (DDT). We will continue to assess the implications of these findings with respect to the potential for detonation occurrence during severe accidents in nuclear power plants; however, the results produced by this research to date confirm our general view that detonations are an unlikely occurrence during a severe accident. The Russians propose to continue testing in the K0PER facility and to also initiate tests in the RUT facility. The objective of using the RUT facility, which is larger than K0PER, is to investigate the effect of scale and configuration on turbulent jet initiation of detonations and deflagration to detonation transition (DDT). Details on the proposed research are provided in the enclosure (Addendum 4 to Appendix A of the Implementing agreement on Severe Accident Research between USNRC and RRC).
To ensure that the research done provides useful results to the NRC, we intend to maintain close interaction with the Russian researchers and provide more oversight by the NRC.
RASPLAV PROGRAM This program, which has both experimental and theoretical elements, has t
as its primary objective the evaluation of whether and under what conditions can a molten core be retained inside the pressure vessel by cooling it from the outside. The large scale integral experimental facility will utilize U0, corium and salt melts in a geometry representing the lower head of a reactor pressure vessel.
The cross section may be hemispherical (as in OECD country's Light Water Reactors) or elliptical (VVER). About 200 Kg of U0, corium melt can be used. The melt is heated to simulate decay heat and cooled by molten salt coolant flowing around the outside of the simulated lower head wall.
Planned measurements include melt and wall temperatures, local heat fluxes to the wall, heat losses, crust formation and its dynamics and local velocities. These will be supplemented by post-test analysis of solidified melt and structural material. Two test configurations are i
being considered; RASPLAV-A, using a 2-dimensional slice geometry to represent the lower head, and RASPLAV-B, using a 3-dimensional geometry with axial symmetry to represent the lower head. Completion of design feasibility, including choosing one of the two RASPLAV designs, consideration of alternative methods of heating and the impact of Lorentz forces, and an assessment against project requirements are part of the OECD RASPLAV Project. We intend to continue our support for the RASPLAV design phase; once it becomes an OECD sponsored project, we plan to continue supporting it under the OECD auspices.
MODEL DEVELOPMENT The NRC has been actively involved in developing the severe accident codes SCDAP/RELAP5, CONTAIN, and MELCOR. These codes have the capability of performing severe accident analyses for Probablistic Risk Assessment and/or accident management studies.
Several improvements to
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these codes have been identified by the NRC staff and the review panels that peer-reviewed these codes. The Russian Academy of Sciences can contribute in this area by participating in the model development activities. A few specific topics of interest to us are core melt progression modeling, debris bed coolability modeling, and fission product release during core concrete interaction.
Irradiation and Annealina of U.S. RPV Steels in Novovoronezh-5 Reactor:
During the course of act4vities under JCCCNRS Working Group 3,
" Radiation Embrittlement, Structural Integrity and Life Extension of Reactor Pressure Vessels and Supports," an exchange program of irradiation of pressure vessel steels in the opposite state's reactor facilities has begun. At present, samples of Russian pressure vessel steels are being irradiated in the Ford Nuclear Reactor at the University of Michigan under NRC sponsorship through the Heavy Section Steel Irradiation Program at Oak Ridge, while samples of a U.S. pressure vessel steel and weld are being irradiated in the Russian Novovoronezh-5 (NV-5) reactor. These exchange irradiations are expected to be exceptionally valuable since they will provide " benchmarks" for direct comparison of irradiation response trends for Russian and U.S. steels against both the Russian and the U.S. embrittlement trends.
As an additional benefit, and one that was not contemplated by the protocol agreement establishing just the embrittlement exchange, the U.S. materials will be post-irradiation annealed by Russia under two different temperature conditions and reirradiated in the NV-5 reactor.
This will simulate a situation wherein a reactor could have approached the PTS Screening Criterion and the licensee decided to anneal in order to continue operations. Annealing response and reembrittlement behavior of U.S. steels and welds is an important issue for some plants that might reach the PTS Screening Criterion before the end of their original 40-year license, or at some time into a 20-year license renewal period.
Thus, the Division of Engineering of the Office of Nuclear Regulatory Research has studies underway to irradiate and anneal appropriate materials from U.S. pressure vessels for formulation of a data base for comparison to predictions of annealing and reembrittlement response from licensees desiring to anneal their reactor vessels. The exposure conditions from the NV-5 irradiation will represent the neutron spectrum and irradiation rate of a power reactor rather than of a test reactor, and thus, the data will be a very valuable addition to the U.S. data base.
The original protocol agreement called for simply irradiation of steels in the opposite state's reactors, with costs to be borne by the host country. In the case of Russian irradiation of U.S. materials, however, annealing and reirradiation have now been added. The additional cperations at the NV-5 reactor for manipulation of the specimens and capsules into and out of an annealing furnace for the two different temperature cycles plus reinsertion following annealing and
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reirradiation were not originally contemplated, and will cost $25K. All other costs for the Kurchatov Institute for facilities, personnel, and testing of the specimens will be borne by the Kurchatov Institute according to the original protocol agreement.
Given the progress to date on the above programs, we believe that it is in the best interest of NRC to extend the existing agreement for another 3 years to allow continuation of these programs. A draft Addendum to the Agreement is L
enclosed for information.
It is my intent to sign this Addendum and forward it to the Institute.
The cost to the NRC of the research summarized above and i
described in the Addendum to the Agreement would be $675K in FY94.
I will continue to keep the Commission informed of progress on NRC sponsored research at the Russian Research Center activities along with that research conducted for the NRC by the Russian Academy of Sciences.
^
t J
s M.
aylor
, Executive Director for Operations
Enclosures:
1.
NUREG/CR-6072 (Commissioners, SECY, 0GC only) 2.
Addendum 4 to Appendix A I
DISTRIEUTION:
Commissioners OGC OCAA OIG OPA OIP OCA EDO ACRS SECY f
[
- The severe accident research is conducted under the auspices of the Memorandum of Cooperation in the Field of Civilian Nuclear Reactor Safety f
between the United States of America and the Union of Soviet Socialist Republics, signed at Washington on April 26, 1988 (the Memorandum).
The Memorandum expired April 26, 1993.
The exchange of diplomatic notes to extend the Memorandum for another 5 years, that is until April 26, 1998, remains unsigned by the Russian Federation.
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ADDENDUM 4 TO APPENDIX A 0F THE IMPLEMENTING ARRANGEMENT ON SEVERE ACCIDENT RESEARCH BETWEEN THE UNITED STATES NUCLEAR REGULATORY COMISSION (USNRC)
AND RUSSIAN RESEARCH CENTER (RRC), FORMERLY THE I.V. KURCHAT0V INSTITUTE FOR ATOMIC ENERGY (IAE)
Considering that, 1.
In accordance with Article VI. D of the Implementing Arrangement on Severe Accident Research between the United States Nuclear Regulatory Comission and the Russian Research Center (hereafter referred to as the Implementing Arrangement), the parties have agreed to this Addendum to Appendix A of the Implementing Arrangement.
2.
The USNRC and RRC have cooperated in the field of severe accident research under Implementing Arrangement signed on October 11, 1990, and extended by Addendum 3 to October 11, 1995.
3.
The RRC has performed extensive research in the area of hydrogen combustion and detonation at conditions representative of severe reactor accidents. The USNRC and RRC are presently cooperating in this research program under a one year Addendum 3 to Appendix A of the Arrangement.
ARTICLE I - PROGRAM COOPERATION The cooperative program includes (1) participating in a program to develop a scaling methodology for spontaneous detonations, and other hydrogen related research, (2) developing models and performing assessment for NRC severe accident codes, (3) continue the RASPLAY design feasibility, and (4) participate in a program of irradiation and annealing of U.S. RPV steels in the Novovoronezh-5, reactor. The NRC program will consist of technical assistance and cash contributions to permit defraying some of the cost of conducting the above described program.
ARTICLE II - SCOPE OF THE ADDENDUM A.
USNRC Scope of Responsibility The USNRC shall provide over the duration of this Addendum the following specified goods and services related to nuclear reactor' severe accident research:
1.
Limited technical assistance and advice will be provided during the conduct of the hydrogen test program; the extent of such assistance to be mutually agreed to prior to the start of the program.
2.
Financial Suppor_t - Subject to the availability of funds, the NRC will provide to RRC and the Russian Academy of Sciences (RAS) the
2 sum of $675K in FY94. Since this agreement is with RRC and the work will be performed by the RAS as well as the RRC, the RRC should provide a detail work slan on the research to be conducted along with the organization t1at will perform the research and the expected completion date. This plan should include an RAS input.
The funds will be used to develop the necessary analyses to define 1
the experiments and to defray some of the costs associated with:
(1) conducting hydrogen experiments, (2) support for the RASPLAV project, (3) model development for NRC severe accident code (s),
and (4) irradiation and annealing of U.S. RPV steels in the Novovoronezh-5 reactor. $250K will be designated for the hydrogen program, and $200K will be designated for models developments for MELCOR, SCDAP/RELAP5/M003, and CONTAIN at the Russian Academy of Scierxes, $200K to support the RASPLAV Project, and $25K for the irradiation and annealing of U.S. RPV steels. RRC will disburse these funds as stated above to those organizations identified to perform the research. NRC support for the RASPLAV activity will continue until OECD assumes responsibility of that Project. At that time, NRC support to RASPLAY Project will be through OECD.
The payment of $300K U.S. dollars is to be paid 30 days after signature of this Addendum. Upon completion of a work plan acceptable to both sides, an additional $375K U.S. payment will be due in July 1994 after approval of technical requirements to implement the plan. Payment will be made, upon receipt of RRC invoices, subject to U.S. government rules and regulations.
B.
RRC Scope of Responsibility The RRC shall provide over the duration of this Addendum the following specific goods and services related to nuclear reactor severe accident research:
1.
Theoretical Ana1YSiS and Numerical Simulation - RRC will continue the analysis and calculations on hydrogen combustion behavior and will provide data on deflagration to detonation transition (DDT) and spontaneous detonation scaling methodology. The objectives of this program include:
a.
Evaluation of the conditions for possible development of strong hydrogen explosion processes due to DDT.
b.
Investigation of the link between mixture composition and dynamic detonation properties c.
Evaluation of the effect of facility scale and configuration on possible development of strong hydrogen explosion processes due to DDT.
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3 2.
Hydroaen Deflaaration and Deflaaration to Detonation Transition (DDT) Experiments - RRC will continue to provide experimental data and conduct necessary additional hydrogen deflagration experiments in the K0PER facility in Russia under joint sponsorship of RRC and NRC. The RRC also will use the RUT facility (a 100 to 500 cubic meter facility compared to 50 cubic meter of the KOPER facility) to further investigate the scale effect on hydrogen deflagration and DDT.
Future experiments would continue to examine the effect of multiple compartments, multiple igniters and large scale. The objectives of this program include:
a.
Investigation of hydrogen / air mixture combustion behavior in large scale (50 cubic meter and 100 to 500 cubic meter) experiments as a function of mixture composition.
b.
Determination of the conditions for detonation onset due to hot turbulent jet injection, c.
Investigation of the effect of scale on hot turbulent jet detonation initiation conditions.
d.
Verification of theoretical models of DDT and hot turbulent jet initiation possibility.
3.
Structure Conseauences of Detonation - The RRC should provide a technical assessment of the structural consequences of localized j
pressures within the detonation wave (i.e., triple point pressures). This assessment should include an analyses of the structural response of a typical steel containment boundary.with a 4 cm thick steel shell. Additionally, this evaluation should describe validation of the analytical method used to predict the pressures.
4.
Seoaration Criteria for Ioniters - The RRC should provide criteria for placing hydrogen igniters inside containment to preclude the onset of hydrogen combustion related loads that can pose a threat to containment integrity.
5.
Models Development for NRC Severe Accident Codes - The Russian Academy of Science will:
a.
Implement the melt spreading model, developed under the auspices of Addendum 3, into the NRC CORCON M003, b.
Develop a physically based model to predict the heat transfer rate at corium water interface during periods of (1) high gas flow rate, (2) low gas flow rate, (3) a j
floating crust layer on top of corium i
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4 c.
Improve the CORCON-H003 code by incorporating melt liquidus temperatures from the ANL experiments for the various core-concrete mixtures, by including ruthenium and molybdenum vapor chemistry into VANESA, by extending the condensed phase chemical reactions to include all silicate, Zr0,, and other reactions, and by implementing non-ideal oxide chemistry modelling. After incorporating these models into the code the RAS will perform analyses against applicable experimental data (ACE, SURC) to verify the improvement in analytical capability.
d.
Develop models to consider simultaneously the thermal, chemical and mechanical behavior of the cladding which include: model of UD,/Zr/ steam interactions, model for U0, dissolution by molten Zry, candling model, model of mechanical behavior of cladding, and quenching model.
e.
Perform pre-test analyses of the NRC experiment at Penn State to study the downward facing boiling heat transfer from the external surface of reactor pressure vessel lower head submerged in water.
6.
RASPLAV Proaram - RRC will continue the feasibility study and scaling consideration regarding the RASPLAY project initiated under this agreement.
7.
Irradiation and Annealina of U.S. RPV Steels in Novovoronezh-5 Reactor -
U.S. materials will be post-irradiation annealed by Russia under two different temperature conditions and reirradiated in the NV-5 reactor. This will simulate a situation wherein a reactor could have approached the PTS Screening Criterion and the licensee decided to anneal in order to continue operations.
8.
Reportina and Meetinas - RRC will prepare quarterly status reports for all programs, and provide final technical reports for each program at the completion of the work described in this Addendum.
Periodic technical meetings may be called for by either party to discuss programmatic or technical issues that might arise during the duration of the program described here. RRC shall provide certification that the funds have been dispersed to the appropriate organization responsible for the research activities as called for in this Addendum.
]
9.
Duration and Termination - The work described in this Addendum shall begin upon signature by the parties and is expected to be completed on or before December 31, 1995. The work described in this Addendum may be terminated by mutual consent or by either party's withdrawing from the present Implementing Arrangement after providing the other party written notice 6 months prior to its intended date of withdrawal.
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III. FINAL PROVISIONS All terms and conditions of the Implementing Arrangement will apply to this Addendum. The parties further agree to modify or extend the activities described in this Addendum within the intended scope of this Addendum upon written agreement of its Administrators.
In witness whereof this Arrangement has been entered into the day and year last written.
FOR THE UNITED STATES NUCLEAR REGULATORY C0ffilSS10f BY:
James M. Taylor k
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TITLE:
Executive Director Operations DATE:
i.clM/s3 PLACE:
M RAG /d MI/.
U8A FOR THE RUSSIAN RESEARCH CENTER (RRC) FORMERLY THE I.V. KURCHATOV INSTITUTE OF ATOMIC ENERGY BY:
N.N. Ponomarev - Stecnov TITLE:
First Deputy Director DATE:
PLACE:
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