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Perpetual Atomics, QSA Global produce Am fuel for nuclear space power
U.K.-based Perpetual Atomics and U.S.-based QSA Global claim to have achieved a major step forward in processing americium dioxide to fuel radioisotope power systems used in space missions. Using an industrially scalable process, the companies said they have turned americium into stable, large-scale ceramic pellets that can be directly integrated into sealed sources for radioisotope power systems, including radioisotope heater units (RHUs) and radioisotope thermoelectric generators (RTGs).
R. M. Versluis, A. J. Mockel
Nuclear Science and Engineering | Volume 58 | Number 1 | September 1975 | Pages 75-88
Technical Paper | doi.org/10.13182/NSE75-A26768
Articles are hosted by Taylor and Francis Online.
In this paper an improved degenerate kernel is obtained and subsequently used instead of the exact thermalization kernel for the calculation of thermal-neutron densities in a heterogeneous reactor lattice.The degenerate kernel is composed of a number of functions, some of which are obtained by conserving speed moments of the kernel while the remaining functions are chosen so as to reproduce scattering probabilities involving epithermal energies. The degenerate kernel satisfies the detailed balance strictly and, as opposed to conventional degenerate kernels, shows the desirable feature of improved accuracy when the number of terms in the degenerate kernel is increased.This degenerate kernel is employed to compute thermal-neutron spectra in cylindricized unit cells by solving the integral transport equation for the scalar neutron density. For this purpose the DESMOS code was developed. The results of these calculations are compared with the analogous THERMOS code results. DESMOS proves to be accurate and its speed of execution compares favorably with that of THERMOS.
