Post-test calculation of thermal-hydraulic behaviour in Demona experiment B3 with various computer codes used in EC Member States

European Commission Directorate-General For The Information Society And Media Directorate-General For Research And Innovation

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Nuclear energy and safety
Energy research

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• Publié par: EUROPEAN-COMMISSION-DIRECTORATE-GENERAL-FOR-THE-INFORMATION-SOCIETY-AND-MEDIA-DI
• Nombre de lectures: 4
• Langue: English
• Poids de l'ouvrage: 2 Mo

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Commission of the European Communities
nuclear science
and technology
Post-test calculation of
thermal-hydraulic behaviour
in Demona experiment B3
with various computer codes
used in EC Member States Commission of the European Communities
Post-test calculation of
thermal-hydraulic behaviour
in Demona experiment B3
with various computer codes
used in EC Member States
J. Gauvain
Commissariat à l'énergie atomique
Institut de protection et de sûreté nucléaire
Centre d'étude nucléaire de Fontenay-aux-Roses
BP n° 6
F-92265 Fontenay-aux-Roses Cedex
Contract No PSS-0025-F
Final report
Directorate-General
Science, Research and Development
1989 EUR 12197 EN Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
L-2920 Luxembourg
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting
on behalf of then is responsible for the use which might be made of
the following information
Cataloguing data can be found at the end of this publication
Luxembourg: Office for Official Publications of the European Communities, 1989
ISBN 92-825-9962-0 Catalogue number: CD-NA-12197-EN-C
© ECSC-EEC-EAEC, Brussels · Luxembourg, 1989
Printed in Belgium CONTENTS
Page
AIMS OF THE STUDY 1
PROBLEM SELECTION 3
2.1. Description of DEMONA
2.1.1. General
2.1.2. The facility
2.1.3. Thermodynamic instrumentation 4
2.1.4. Additional equipment 5
2.2. Description of the experiment B3
2.2.1. Overview
2.2.2. Summary of the 5 phases 6
ORGANIZATION OF THE EXERCISE 8
3.1. Participants
3.2. Presentation of results 10
3.3. Timing
INPUT DESCRIPTION2
4.1. Reference case
4.2. Case with fixed steam input3
CODES SHORT DESCRIPTION AND SPECIFIC ASSUMPTIONS 14
5.1. AERCEL 1
5.1.1. Short description
5.1.2. Specific assumptions 15
5.2. COBRA-NC6
5.2.1. Short description
5.2.2. Specific assumptions for Modeling the DEMONA B3
Experiment 21
5.2.3. Conclusion for the COBRA-NC calculation 2
5.3. CONTAIN 1.067
5.3.1. Short description
5.3.2. Specific assumptions 30
5.4. CONTAIN 1.10
5.4.1. Short description
5.4.2. Specific assumptions3
5.5. CONTEMPT-LT 34
5.5.1. short description
5.5.2. Specific assumptions
5.6. CONTEMPT 4 - MOD 55
5.6.1. Short description
5.6.2. Specific assumptions6
5.7. FUMO9
5.7.1. Short description
5.7.2. Specific assumptions 40
5.8. JERICHO 41
5.8.1. Short description
5.8.2. Specific assumptions4
5.9. MARCH2-UK
5.9.1. Short description
5.9.2. Specific assumptions8 Page
6. DISCUSSION OF RESULTS FOR REFERENCE CASE 54
6.1. General observations 5
6.2. Results
6.2.1. Total pressure
6.2.2. Steam partial pressure5
6.2.3. Atmospheric temperature
6.2.4. Inner side of outer wall temperature 5
6.2.5. Saturation ratio
6.2.6. Steam condensation rate on walls6
6.2.7. Bulkn rate
6.2.8. Water mass sump
6.2.9. Sump temperature7
6.2.10. Heat transfer coefficient 5
6.2.11. Used input for steam mass flow rate
6.3. Limitation of the exercise8
7. CONCLUSIONS AND RECOMMENDATIONS9
7.1. Conclusions 5
7.2. Recommendations
8. ACKNOWLEDGMENT 61
9. REFERENCES2
APPENDIX 77
DEMONA B3 T/H EXERCISE 89
- IV -1 - AIMS OF THE STUDY
Recent discussion about the aerosol codes currently used for the
analysis of containment retention capabilities have revealed a number of
questions concerning the reliabilities and verifications of the thermal-
hydraulic modules of these codes with respect to the validity of imple­
mented physical models and the stability and effectiveness of numerical
schemes.
Since these codes are used for the calculation of the Source Term
for the assessment of radiological consequences of severe accidents, they
are an important part of reactor safety evaluation.
For this reason the Commission of European Communities (CEC), fol­
lowing the recommendation made by experts from Member States, is promo­
ting research in this field with the aim also of establishing and increa­
sing collaboration among Research Organisations of member countries.
In September 1986 the CEC organised a comparative exercise based on
the experiment LA-Α of the LACE program, with the aim of testing con­
tainment thermal-hydraulics and aerosol codes used in the Member States
for the Safety analysis of LWR plants.
In 1986 the CEC sponsored too a benchmark exercise (1) on aerosol
calculation based on DEMONA B3 experiment. The results of this exercise
were very sensitive to the calculation of energy and mass transfer bet­
ween the phases.
In view of the results of the studies summarised above, the CEC has
decided to carry out a Benchmark exercise for severe accident containment
thermal-hydraulics codes. Thise is based on experiment B3 in the
DEMONA program.
- 1 -The main objective of the benchmark exercise has been to assess the
ability of the participating codes to predict atmosphere saturation
levels and bulk condensation rates under conditions similar to those
predicted to follow a severe accident in a PWR. This exercise follows
logically on from the LA-4 exercise, which is related to an experiment
with a simpler internal geometry.
Several research organisations of the Community Member Countries
have participated at this Benchmark Exercise, and the codes used in the
exercise are among the more advanced in the treatment of thermal hydrau­
lic needed for aerosol transport calculations.
It was not the purpose of this Study to analyze the causes of possi­
ble deviations among the results obtained from different codes and users
unless they are clearly obvious. For a thorough explanation of such dif­
ferences a detailed investigation of the differences in modelling would
be necessary as had been done in the past for a small number of codes. It
may be a recommendation for future work to perform such an analysis.
- 2 2 - PROBLEM SELECTION
2.1 - Description of DEMONA
2.1.1 - General
The DEMONA (Demonstration of Nuclear Aerosol behavior) program (2)
was conducted to demonstrate the natural aerosol removal behavior during
core melt accidents in LWRs and to validate the aerosol computer code
NAUA (3) and the related thermodynamics code COCMEL (4). Participants in
the program were Kernforschungszentrum Karlsruhe, the Swiss Federal Ins­
titute for Reactor Research Würenligen, Battelle-Institut e.V. Frankfurt,
Kraftwerk Union Erlangen, and Gesellschaft für Reaktorsicherheit
Garching/Köln.
One particular objective of the program was to check the applicabi­
lity of the single well mixed volume concept which is underlying both in
NAUA and COCMEL. Having in mind that inhomogeneities might well occur in
certain instances of an accident or an experiment it is nevertheless
believed that a single compartment treatment will not result in too large
errors in the overall leaked mass i.e. the source term.
The experiments of the DEMONA program have been finished in June
1986. Nines have been conducted by this time. Results of the
experiments have been published in (5, 6, 7).
2.1.2 - The Facility
The DEMONA experiments were performed in the Battelle Franckfurt
model containment (640 m3 capacity) which originally was designed for
blowdown investigations, on 1:64 scale related to the German PWR plant
Biblis A. For the DEMONA experiment B3 some of the original internal
partition walls of the model containment were removed, and the remaining
compartments were connected by the maximum possible vent areas to appro­
ximate a single-compartment geometry, cf. Fig.2.1. The inner and outer structures of the model containment are built from conventional reinfor­
ced concrete with a surface coating. The cylindrical outer containment
wall is partly surrounded by Ytong brick wall.
An adequate steam-air-aerosol test atmosphere in the model contain­
ment was provided by a 2.5 t/h steam generator and a plasma-torch aerosol
generator with a capacity of 300 g/min Sn03 aerosol.
2.1.3 - Thermodynamic instrumentation
Besides a large variety of aerosol measuring systems the facility
was also equipped with the following instruments :
2 transducers for containment pressure
31 thermocouples and resistance thermometers to monitor atmosphere
temperature distribution
12 thermocouples for sump temperature
15s for concrete structure temperatures
2 heat transfer measuring blocks
1 transducer for atmosphere humidity
5 sump level gauges
various systems to monitor steam and air injection, aerosol gene­
rator operation and containment leak rate.
- 4