Calculations presented were done to determine what maximum temperature gradients and stresses would be in typical designs of flat thorium plates, 100 mils thick and coolled on both sides by NaK.

Five isotopes of bismuth occur in nature. Using particle accelerators providing helium ions up to 40 Mev in energy and deuterons up to 20 Mev in energy, it was possible to produce and identify two artificial radioactive isotopes. With the advent of the 184-inch Berkeley syncho-cyclotron and its hundreds of Mev energies, it was possible to form highly neutron-deficient bismuth isotopes extending more than ten mass units below stable Bi(209).