Objective
To develop, validate and distribute to the EC Institutions the European Accident Code-2 for the improved best estimate calculation of unprotected Loss-of-Flow. Transient Overpower and Loss-of-Heat Sink accidents in Liquid Metal Fast Breeder Reactors.
The emphasis was on the validation of the European accident code 2 (EAC-2) code with irradiated CABRI in pile experiments and related necessary improvements to the code. The coupling with a simplified version of the space time neutronics called HXSPRT was achieved. Further improvements were made to the XEXNOD static neutronics calculation and the detailed space time kinetics HEXNODYN. More generally a more robust EAC-2 version was generated through testing on different computers.
The analysis of CABRI experiments with EAC-2 required a new code option which allowed an imposed coolant flow rate and several flow cross section changes. Improvements to the TRANSURANUS fuel pin behaviour code, the CAMDYN model for treating molten fuel motion inside the pin and the MDYN model for channel fuel motion were needed to account for the strong radial nonuniformity of the neutron flux in the CABRI experiments. Experiments BI-2, BI-4 and AI-3 were fully analysed and experiment BI-3 was calculated up to cladding motion inception, which cannot yet be treated by EAC-2. With the stand alone TRANSURANUS/CAMDYN model AIR and A3 were reanalysed and new analyses were made for AI1, AI-3 and BI-2.
For a simplified time dependent (adiabatic) neutronics treatment the HXSPRT code was coupled to EAC-2. HXSPRT includes the static HEXNOD diffusion and transport calculation, the KWIKXS cross section generator and the PERT reactivity worth calculation. Further improvements to the static HEXNOD code were also made. This concerns the separate treatment of uncollided neutrons which is important for accident situations. The detailed quasistatic time dependent neutronics was upgraded so that it can be coupled to EAC-2.
Progress to end 1991
The emphasis in this year was on the validation of EAC-2 code with irradiated CABRI in-pile experiments and related necessary improvements were made to the XEXNOD static neutronics calculation and the detailed space time kinetics HEXNODYN. More generally a more robust EAC-2 version was generated through testing on different computers.
The analysis of CABRI experiments with EAC-2 required a new code which allowed an imposed coolant flow rate and several flow cross section changes. Improvements to the TRANSURANUS fuel pin behaviour code, the CAMDYN model for treating molten fuel motion inside the pin and the MDYN model for channel fuel motion were needed to account for the strong radial non-uniformity of the neutron flux in the CABRI experiments. Experiments BI-2, BI-4 and Al-3 were fully analysed and experiments BI-3 was calculated up to cladding motion inception, which cannot yet be treated by EAC-2. With the stand-alone TRANSURANUS/CAMDYN model AIR and A3 were re-analysed and new analyses were made for Al1, Al-3 and Bl- 2.
For a simplified time-dependent (adiabatic) neutronics treatment the HXSPRT code was coupled to EAC-2. HXSPRT includes the static HEXNOD diffusion and transport calculation, the KWIKXS cross section generator and the PERT reactivity worth calculation. Further improvements to the static HEXNOD code were also made. This concerns the separate treatment of uncollided neutrons which is important for accident situations. The detailed quasistatic time dependent neutronics was upgraded so that it can be coupled to EAC-2.
Detailed description of work foreseen in 1992 (expected results)
Further analysis of higher burn-up CABRI experiments is needed. For analysing experiments or accidents beyond the point of fuel pin destruction, the modelling of pin break-up is needed in the TRANSURANUS/CAMDYN model and in the MDYN model. In the latter the treatment of molten steel motion has to be also completed. The AGT4 group of the European Fast reactor (EFR) project will recommend what new modules should be added or wether certain modules should be exchanged with other ones from the American SAS4A or the English FRAX5-C code.
In the area of neutronics the HEXNODYN quasistatic code should be coupled to the HXSPRT code and the entire package to EAC-2. Work on a fast recalculation of the transport response matrices is necessary and further validation efforts of the time-dependent neutronics is needed. Moreover considerably more code documentation is necessary.
Short description of the evolution of work in 1993
Further model additions as recommended by the AGT4 group of the EFR should be made. Validation efforts with CABRI experiments should continue and accident studies for different accident initiators and reactor sizes should be undertaken.
Topic(s)
Data not availableCall for proposal
Data not availableFunding Scheme
Data not availableCoordinator
21020 Ispra
Italy