TIBER activation analysis: Appendix A-3

TIBER-II is an engineering test reactor designed to establish the technical feasibility for fusion, and is a US option for the prospective International Thermonuclear Test Reactor (ITER). The TIBER-II baseline design has 3 m major radius, 3.6 aspect ratio, and 1.1 MW/m2 average neutron wall loading. The inboard shield is about .5 m thick and structurally consists of tungsten alloy and PCA alloy. The outboard is 1.52 m thick and utilizes PCA as structure and beryllium as a neutron multiplier. An aqueous solution of 160 g LiNO3/liter is used throughout as a coolant and breeder. A one-dimensional cylindrical model for TIBER is used to calculate the neutron flux and the radioactivities. Activities are calculated during and after 2.5 full power years (FPY) of operation. TIBER total activity is ∼2 MCi/cm at the end of operation and is dominated by the inboard activity. The high volumetric fraction of the PCA/W alloys in the inboard shield, used to provide magnet protection at the limited inboard space, makes the inboard specific activity two orders of magnitude higher than that of the outboard and dominant all the time. The decay heat due to β and γ decay produces about .05 W/cc in the inboard at shutdown and for a few weeks. Under adiabatic conditions, this heat would raise the inboard shield temperature up to 11500C. A considerable part of this heat is generated by the γ decay which might help, through the γ transport, to smooth the heat concentration. Waste disposal ratings of the TIBER structures have been calculated, and it is found that both the inboard and the outboard shield are classified as Class C radwaste. 4 refs., 4 figs., 3 tabs