A programme of neutron experiments in IPPE on the ADS problem

A general concept of Accelerator Driven Systems (ADS) with two blanket regions - inner fast spectrum blanket (F-blanket) and outer thermal blanket (T-blanket) has been developed in Russia. The ADS takes advantage of the exceptional properties of liquid lead-bismuth, both as nuclear coolant and as a spallation neutron source. Liquid Pb-Bi with natural convection pumping is used as target material and coolant in F-blanket. The sub-critical inner F-blanket operates in the fast neutron spectrum region that ensures optimal destruction efficiency for the actinides. The outer T-blanket is a vessel with heavy water moderator and CANDU-type pressure tubes. Fuel pins are made of mixed commercial Pu or weapons-grade (WG) Pu + actinides and Th oxides clad in stainless steel for the F-blanket and zirconium alloy for the T-blanket. Thermal power output is 300-600 MW and 200 MW provided by 99Tc dissolved in heavy water moderator and continuously extracted from the system at a proper rate. Experimental investigations on ADS systems are carried out in the following areas: ADS models study (both bound fast-thermal and one-zone models); creation of experimental benchmarks based on Pb (or Pb-Bi) coolant; integral experiments on the problem of minor actinides; creation of experimental benchmarks for Th neutron data testing. (R.P.)