Activation and waste disposal of the TITAN RFP reactors

AbstractThe TITAN-I lithium self-cooled and TITAN-II aqueous lithium nitrate solution-cooled fusion reactors are based on the reversed-field-pinch (RFP) toroidal confinement concept and operate at high power density with an 18.1 MW/m2 neutron wall loading. These designs were analyzed to study the activation and waste disposal asepects of such high-power density reactors. It was found that because of the use of V-3Ti-1Si (TITAN-I) and reduced activation ferritic steel (TITAN-II) as structural alloys for the first wall, blanket, reflector, and shield components, all the TITAN components except the divertor collector plates can be classified as shallow-land burial (10CFR61 Class C or better) nuclear waste for disposal, provided that the impurity elements, niobium and molybdenum, can be controlled below about 1 and 0.3 appm levels, respectively. The average annual disposal masses were estimated to be 150 and 96 tonne, respectively, for the 1000 MW electric TITAN-I and TITAN-II reactors. This corresponds to about 11% of the total mass in the fusion power core of both reactors. The divertor collector plates are fabricated with W-Re(26 wt%) alloy because of its low particle sputtering properties. The waste disposal ratings of the divertor collector plates in the TITAN-I and TITAN-II reactors, however, are estimated to be factors of 10 and 2, respectively, higher than allowed for Class C disposal. The annual disposal mass of this non-Class C waste is 0.35 tonne, less than 0.4% of the average annual discharge mass for both TITAN-I and TITAN-II reactors. An additional 74 m3 annual discharge of Class C waste containing 14C may be needed for the TITAN-II reactor because of the use of nitrate salt in the aqueous coolant as the tritium breeder. The conclusions derived from the TITAN reactor study are general, and provide strong indications that Class C waste disposal can be achieved for other high-power density approaches to fusion, for example, the tokamak.