| 50 | | Considering the most important isotopes in a e.g. VVER-440 reactor with fresh fuel: 1H, 2H, 4He,10B, 11B 16O, 17O, 90Zr, 91Zr, 92Zr, 94Zr, 96Zr, 93Nb, 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, 158Gd, 160Gd,174 Hf, 176Hf, 177Hf, 178Hf, 179Hf, 180Hf,235 U, 238U, with 8 different materials definedto store the cross section data for a given temperature 102,4 MB memory is needed on the GPU. For a realistic VVER-440 power plant with full detailed modelling the cross section date reaches 5Gb in memory need. The videocards available contain 2 (GTX 690) or 8 (GTX 1080) GB memory each for realistic simulations therefore modern videocards offer enough physical memory. |
| | 50 | Considering the most important isotopes in a e.g. VVER-440 reactor with fresh fuel: 1H, 2H, 4He,10B, 11B 16O, 17O, 90Zr, 91Zr, 92Zr, 94Zr, 96Zr, 93Nb, 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, 158Gd, 160Gd,174 Hf, 176Hf, 177Hf, 178Hf, 179Hf, 180Hf,235 U, 238U, with 8 different materials defined to store the cross section data for a given temperature 102,4 MB memory is needed on the GPU. For a realistic VVER-440 power plant with full detailed modelling the cross section date reaches 5Gb in memory need. The videocards available at our institute contain 2 (GTX 690) or 8 (GTX 1080) GB memory each for realistic simulations therefore modern videocards offer enough physical memory. This latter example is considered as extreme in memory need. |
| | 51 | |
| | 52 | == Neutron Transport |
| | 53 | |
| | 54 | The particle transport is based on conventional Woodcock method where we need to generate the majorant cross sections for a combined energy |
| | 55 | lattice in advance. For real scattering first we reduce the weight of the particle by the probability of survival using implicit capture then we draw a reaction by the cross sections. We consider reactions with the following MT numbers: |
| | 56 | |
| | 57 | MT=2, 5, 11, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 41, 44, 45, 51-90, 101. |
| | 58 | |
| | 59 | After choosing the reaction, the determination of the new energy and angle of the neutron depends on the given ACE law (ACE Law 3, 4, 7, |
| | 60 | 9, 11, 44, 61, 66 ). The angle distribution can be isotropic or given in table format. The coordinate system of the given data should also be considered. |
| | 61 | |
| | 62 | On the geometry seen in Figure 2 at t = 0s we place a 0.1MeV energy source at 0,0,0 point. Figure 3 shows how power density develops in |
| | 63 | time steps. On Figure 4 the distribution evolved after 1ms is plotted. There is a possibility of saving the trajectory of the neutrons. On Figure 5. for a 235U sphere at t = 0s we started neutrons at 1eV energy from 0,0,0 point. The first reactions of 500 neutrons is shown on the figure where we indicate elastic scattering with color green, fission with red, every other reaction with yellow. |
