RPS strategies to enable NASA's next decade robotic Mars missions

Safe radioisotope thermoelectric generators and heat sources for space applications

“…5 and 6 that the neutron yield from the (a, n) reaction with 17 O and 18 O is the dominant feature in the total neutron spectra for both 238 PuO 2 and 241 AmO 2 . Upon examination of the total neutron yield per gram of 241 Am and 241 AmO 2 , there is a stark contrast.…”

“…Although low in concentration, the (a, n) reaction cross-sections for 17 O and 18 O are significant for alpha particles with energies in the range from 0 to 6 MeV. Quantitatively, for alpha particles with energies of 5.5 MeV, the cross-sections of 17 O and 18 O are 206 milibarns and 440 milibarns respectively [26]. The 17 O (a, n) reaction has a Q value of +0.587 MeV and a threshold energy of 0 MeV [27].…”

“…It is suggested that the greater efficiency allows for a reduction in fuel mass when compared to current GPHS-RTG systems [18]. However, this fuel saving is unlikely to translate into a net system mass saving.…”

“…The threshold energy for the 16 O alpha-neutron (a, n) reaction is 15.24 MeV [25] and hence this particular reaction does not occur for 238 Pu or 241 Am in their oxide compounds. Although low in concentration, the (a, n) reaction cross-sections for 17 O and 18 O are significant for alpha particles with energies in the range from 0 to 6 MeV. Quantitatively, for alpha particles with energies of 5.5 MeV, the cross-sections of 17 O and 18 O are 206 milibarns and 440 milibarns respectively [26].…”

“…spectrum was generated using the Monte Carlo N-Particle transport code MCNPX version 6 [24], the statistics from which were derived from the calculation of 1 Â 10 6 spontaneous fission events. and the neutron yields as a result of (a, n) -reactions with 17 O and 18 O obtained through the application of Eqs. (2) and (3).…”