Validering av Casmo-5M / Simulate-3
The objective of this M. Eng. Diploma work was to validate the new version, CASMO-5M, and compare the results with CASMO-4E, by using the same input in both programs. The tasks that were included in this work was to compare TIP-measures, k-effective curves (warm), k-effective curves (cold), the effect of void on k-effective, the isothermal temperature coefficient (ITC), the moderator temperature coefficient (MTC), damping ratio calculations, internal effect in a fuel bundle of a BA-rod, the speed of BA-out burn, impact of xenon, falling control rod, margins and isotopes.The TIP-measures showed that the differences were small for all reactors, at most, 6% nodal improvement by C5M (Casmo-5M) for Oskarshamn 3. The warm measurements of k-effective showed that C5M had a higher value for all cycles of Oskarshamn 1, 2 and 3 in comparison to C4E (Casmo-4E). Important improvements were noted for C5M, which solved the ?tub behaviour? that used to occur in Oskarshamn 2 when using C4E. For all three reactors the the differences of the cold k-effective measurements between C5M and C4E were decreasing by growing reactor cycle, especially after changing fuel rods from SVEA64 to SVEA 96 Optima/Optima2.The new fuel (Optima/Optima2) contains part length fuel rods and contains 10x10 fuel rod positions to compare with the old 8x8/9x9 previously used in all three reactors. The effects of void on k-effective were consistently better in C5M than in C4E for all three reactors. The isothermal coefficient was lower in C5M in comparison to C4E for all three reactors, except in the middle of cycle 34 for O2 where C5M was higher than C4E. The average of MTK is lower in C5M then in C4E for all three reactors.The uniform Doppler coefficients are consistently lower in C5M than in C4E, for all three reactors. In the damping ratio calculations C5M is marginally higher than C4E. For all three reactors C5M consistently calculates a higher effect in the studied fuel bundle of a BA-rod in comparison to C4E, at 0% and 80% void.The speed differences of the BA burnout are marginal, but notably exhibits a consistent behaviour. C5M has a higher power development in the beginning of the cycle?s for all voids (0-80%) and lower in the end of the cycles compare to C4E. The xenon impact has the same trend for all three reactors. C4E has a consistently higher value than C5M in the beginning of the cycles and contrary in the end of cycles. The test of the falling control rod has proved that in C5M we maintain a worse fuel temperature- and moderator coefficient which results in a higher reactivity maximum value, compared to C4E.In C5M we find that the margins are consistently higher than C4E for all three reactors, which is to be preferred. Regarding the isotopes, the only difference observed in the test was that according to C5M there is approximately 50% less U-237. This does not have a big effect on the reactor because this amounts to only about 1/1000 of the total amount of the fuel in the core.