Criticality Safety Calculations for Three Types of Final ... - Posiva

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16(Table 1. continued)B) Comparison between two types of the BWR canister- Enrichment: 3.8%Canisters in air (vacuum)newer designolder designDry canister 0.33478 ± 0.00014 0.33080 ± 0.00014Water filled canister 0.93002 ± 0.00036 0.93609 ± 0.00040C) Impact of enrichmentBWR canister- Water-filled canisters in air (vacuum)Enrichment (%)3.8 0.93061 ± 0.000404.0 0.94215 ± 0.00041VVER canister- Water-filled canisters in air (vacuum)Enrichment (%)4.2 0.94146 ± 0.000444.4 0.95100 ± 0.00041The VVER and BWR canisters loaded with the fresh fuel bundles fulfil the nominal criticalitysafety criteria if the enrichments are 4.2% and 3.8%, respectively. However, either anincrease of the initial enrichment or taking into account the various uncertainties maynecessitate the application of the burnup credit principle.
175.2 EPR canisterTest calculationsIn Ref. (Agrenius 2002) results of criticality safety calculations for the Swedish PWRcanister, which is very similar to the EPR canister design, are reported. The Swedishcalculations have been made with the SCALE code system (KENO V Monte Carlo Code).In the report there are not given all necessary input data. However, useful test calculationscan be performed. Their main results are shown in Table 2, where also the main parametersof the reference case (case 0) are given.Table 2. Multiplication factor of a PWR canister of Swedish design- Four 17x17-(24+1) bundles- Enrichment 4.2 wt%- Water filled canister(s) in the air (vacuum)- Water density 1 g/cm 3- Steel/cast iron composition as defined for the Finnish EPR canister- Steel/cast iron density always 7.85 g/cm 3-Infinite lattice of 105x105 cm 2Case Modified parameter Infinitemultiplication factor0 1.07037 ± 0.000411 water density 0.997 g/cm 3 1.06979 ± 0.000422 steel/cast iron = pure iron 1.08299 ± 0.000443 case 1 and combined 1.08256 ± 0.000414 density of the insert 7.2 g/cm 3 1.07176 ± 0.000445 bundles moved towards the centre 1.07427 ± 0.00040The Swedish results are (Agrenius 2002):Case 0 1.0868 ± 0.0012Case 5 1.0903 ± 0.0012The Finnish and Swedish results would be in good agreement with each other, if the compositionof the insert had been defined to be pure iron in the Swedish calculations. Theresults of the test calculations indicate that the composition of the iron insert and maybealso the copper overpack should be known quite accurately in the criticality safety calculations.
Page 1 and 2: Working Report 2005-13Criticality S
Page 3 and 4: CRITICALITY SAFETY CALCULATIONS FOR
Page 5 and 6: 1CONTENTSPageABSTRACTTIIVISTELMÄ1
Page 7 and 8: 32 MCNP4C COMPUTER CODE AND ITS DAT
Page 9 and 10: 54 INPUT DATA4.1 Geometry and mater
Page 11 and 12: 7~ 55D174210949A21036AVVER 440-type
Page 13 and 14: 9Figure 5. Transverse MCNP model of
Page 15 and 16: 11The material compositions and the
Page 17 and 18: 134.2.3 EPR fuel bundleExact inform
Page 19: 155 MAIN RESULTS5.1 VVER and BWR ca
Page 23 and 24: 19Impact of initial enrichmentThe a
Page 25 and 26: 21The results of Tables 5a and 5b i
Page 27: 23REFERENCESAnttila, Markku, Critic

Criticality Safety Calculations for Three Types of Final ... - Posiva

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