International Atomic Energy Agency IWGFR/52 INTERNATIONAL WORKING GROUP ON FAST REACTORS STATUS OF NATIONAL PROGRAMMES ON FAST BREEDER REACTORS Seventeenth Annual Meeting Vienna, Austria 3-6 April 1984 INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, 1984 STATUS OF NATIONAL PROGRAMMES ON FAST BREEDER REACTORS Seventeenth Annual Meeting Vienna, Austria 3-6 April 1984 Printed by IAEA in Austria August 1984 CONTENTS A review of fast reactor activities in Switzerland — March 1984 5 P. Wycller A review of fast reactor program in Japan — April 1984 10 Y. Matsuno Commission of the European Communities. Review of fast reactor activities - April 1984 35 W. Balz A review of the Italian fast reactor programme 38 F. Pierantoni, R. Tavoni Status of fast breeder reactor development in the United States of America — April 1984 49 K.E. Norton Review of fast reactor activities ir India (1983-84) 68 S.R. Paranjpe A Review of the United Kingdom fast reactor programme — March 1984 77 R.D. Smith Lc developpemcnt des rcacteurs ä neutrons rapides en France — de lcvricr 1983 ä fevrier 1984 108 E. Benoist, L. Champeix CocTOHHiie paBoT no obicrpbirn peaKTopaM B CCCP Ha anpenb 1984 rofla 123 3. A. Xodapee.A.A. PiuieiicKuii The role of the Nuclear Energy Agency in the area of fast reactors 135 M.J. Crijns Status of fast breeder reactor development in the Federal Republic of Germany, Belgium and The Netherlands - February 1984 136 R. Hü per A REVIEW OF FAST REACTOR ACTIVITIES IN In the field of LMFBR safety analytical work is performed on hypothetical SWITZERLAND - March 1984 core disruptive accidents (HCDAs) and on the integrity of components under HCDA loadings with emphasis on the dynamic behaviour of the reactor cover. P. WYDLER A considerable effort has recently been devoted to the preparations for the Swiss Federal Institute for Reactor Research, SONACO natural convection experiment. AnoLher relatively new experimental Wiirlingen, activity, involving small-scale vapour explosions with freon and watec, has Switzerland produced evidence of interesting physical effects which are not In accord with the assumptions of current molten fuel-coolant interaction (MFCI) models. 1. Introduction The fuel development programme has continued with the manufacture of sphere- With the recent startup of the Leibstadt plant nuclear energy in Switzerland pac mixed carbide fuel pins for an irradiation experiment in FFTF. However, has reached another milestone. When the station has reached its full opera- the time scale of the experiment has suffered a set-back due to an incident ting power of 942 MWe, nuclear energy will contribute nearly 40 % to the in a glove box of the production line. total electricity generation of the country. This success is somewhat over- shadowed technically by the high construction cost of the Leibstadt plant Fig. 1 illustrates the allocation of manpower to these tasks. Also indicated (over 5'000 million Swiss Francs), and politically by two pending antinuclear is an attachment of an EIR staff member to CEA-DERS at Cadarache, where he is initiatives expected to be put to the vote in the autumn. Confidence in the involved in the prediction and analysis of the SCARABEE-APL in-pile tests. future of nuclear energy is, however, strengthened by such facts as the in- creasing electricity growth rates (3.4 % in 1983 as against 1.5 1 in the previous year) caused effectively by an oil substitution process, the high reliability of the nuclear power stations (reflected by a 87 % average load factor in 1983) and, not least, a reduced interest of the news media in the Integrity of components 1 .9 nuclear debate due to a sudden preoccupation of the public with the conse- Fuel development / quences of air pollution. 17.0 --/ Attachment SCARABEE — 1.0 Other activities As a result of the noncentralized government in Switzerland there is no 0.7 clear national policy for the future application of nuclear energy. This is reflected in the lack of a generally agreed nuclear energy research policy Total: 35.4 man-years in the country. Consequently, activities related to several advanced reactor concepts are funded simultaneously at similar, but relatively low levels. Natural convection The total expenditure of 5.9 million Swiss Francs (i-l SFr per capita) for 1 0.9 fast reactor activities in 1983 must be judged in the light of this situ- ation. The funds have been allocated to an LMFBR safety programme (52 %) and a fuel development programme (48 %). Distribution of Man-Years Expended in 1983 In the past year it has been possible to strengthen the ties with research was suppressed. The differences between the cases were shown to bo small groups and organizations in other countries. The HCDA work utilizes computer but not negligible, the modified case proceeding to a disassembly phase codes developed by KfK and has received considerable support from KfK somewhat more rapidly (1.8 rather than 2.5 s after beginning of boiling) specialists. The codes SEURBNUK-2 and SEURBNUK/EURDYN, used together and also in other respects being more conservative than the standard with other codes to assess the consequences of HCDAs, will be developed case. further under a tripartite agreement between EIR, Euratom and the UKAEA. A programme for validating and comparing hydrodynamics/structure mechanics computer codes for the pool geometry has been agreed formally with CEA- 2.2 Molten Fuel-Coolant Interaction Studies DRNR at Cadarache, and a parallel agreement with CEA-STT at Grenoble covers a mutual collaboration for the natural convection studies. An The studies of vapour explosions in connection with the MFCI probLem informal information exchange on the latter studies exists also between appear to be leading to the suggestion that there might be an alternative EIR and a team at NPDE Dounreay which helped to give the experiment its explanation for the high pressure usually associated with an MFCI. For initial momentum. over two decades it has generally been assumed that such interactions are characterized by higher than critical pressures produced on a tens The fuel development programme has had for many years agreements with of microsecond time scale and that these pressures originate from rapid fragmentation and heat transfer between the liquid phases within the the UKAEA for studying gel technology and for irradiation tests in DIDO interaction region. Vapour production in current MFCI models, including and DFR and with SCK/CF.N Mol and KfK for tests in BR-2, including also both those explaining the mechanisms (Board-Hall detonation model) and post-irradiation examinations in the EIR hot cells. The activities in those predicting the consequences of an interaction in safety assessment connection with the FFTF experiment are covered by an agreement with analysis, is assumed to cut off heat transfer. the US-DOE. The work at EIR, although on a small scale and restricted to the Freon 22- 2. LMFBR Safety water interaction, indicates that within the interaction region Itself only modest pressures and rise times are produced although high fluid velocities .can arise. It is suggested that it is the stopping of these 2.1 Analysis of Hypothetical Core Disruptive Accidents fluid velocities at relatively incompressible boundaries that gives rise to the supercritical pressures and short rise times. "Hammer" type pressures The CAPRI code from KfK is being used to analyze the initiation phase of over 10 MPa (i.e. pressures exceeding twice the critical pressure of an unprotected LOF accident for the homogeneous core of SNR-1300. of 5 MPa in Freon 22) can readily be produced in the EIR experiment but In this context an examination was made of the consequences of the assump- it is believed that these are not associated with the mechanisms taking tion in the code that once the sodium in a channel has started to boil, place within the interaction region where propagating pressures are about the channel will not be subjected to an MFCI event. Two cases were compared, 0.7 MPa. a normal CAPRI case and a case in which boiling in potential MFCI channels (channels in which after beginning of boiling a MFCI criterion was reached) Evidence to support the proposed mechanism has been obtained from pressure The code development work related to the SEURBNUK code family is performed waves, passing down a tube containing bubbly or two-phase mixtures, meeting in the framework of a tripartite agreement between EIR, Euratom and the UKAEA, an incompressible boundary near the bottom. Very high pressure amplification signed in November 1983. In the context of code development an improved treat- at the boundary has been demonstrated which in some cases aforoaches the ment of the contact of sodium with the reactor roof under oblitjue slug impact theoretical limit of about 60, predicted by a simple analysis for water. conditions is worth mentioning. An improved model which explicitly recognizes It is possible that the near and above critical pressures reported partial impact within a computational cell has enabled numerical spikes in previously by other authors with other materials could also be explained the roof histories to be reduced considerably in amplitude without affecting by this mechanism. the resolution of the physical spikes, i.e. those resulting from actual wave interactions. In the freon-water experiment although condensation of the vapour near the boundary is required to give the observed pressure spike, when the The most recent version of the coupled code SEURBNUK/EURDYN ha« been veri- reflected wave passes through the interaction region the pressure is fied f' " the MARA-1 and APRICOT-6 geometries (The coupled code allows thick much reduced and has a propagation velocity associated with a two phase structures to be represented in the finite element formulation of EURDYN).