Advanced ADS concepts

Current Nuclear Power has already proved its ability to be used as one of the principal means of the large scale energy production throughout the world. There is the widely spread opinion that many of the problems can be resolved if LWR's would be able to close its fuel cycle (MOX-strategy). Really, closure of fuel cycle (if it could be realised technically in full degree) leads to the reduction of the TRU-accumulation rate and of the most worrying long-lived fuel waste by factor of 10 -30 and, hence, to facilitation the waste repository problems. Analysis shows that one of the most important problems with MOX-type fuelled LWR exploitation is its potential safety degradation due to corresponding degradation of some principal physical parameters. Non-favourable feed back effects, delayed neutron fraction reduction, etc. lead, probably, to some important constraints in fuel multirecycling fraction. However, if the LWR's fuel cycle closure would be even realised, other, not less important, key-issues will rest unresolved or even more aggravated such as the economical competitiveness, weapons material proliferation, fuel resources, natural safety level, etc. Possible replacement of LWR's park by Sodium Fast Reactors (SFR) is able to change some accents in NP acceptance, however, can not change this situation drastically. Really, the potential of the waste long-term toxicity reduction is slightly favourable for SFR's than for LWRs (by the factor of 1.5 [1,2]) and this benefit is indebted mostly due to the higher fuel burnup potential of SFR's. Hence, the waste toxicity reduction factor, when SFR fuel cycle will be closed, is expecting to be in the interval 20-50 and, hence, it is slightly better than for LWRs. Nevertheless, it is important to mention that the closure of fast reactors fuel cycles does not lead to important degradation of safety physics. TRU equilibrium inventory is one of penalising factors of fast reactors: the total TRU inventory in NP, based on SFR, will be higher (roughly, by factor of 2) than for LWR based Np