The Multi‐Mission Radioisotope Thermoelectric Generator (MMRTG) will use an improved version of the General Purpose Heat Source (GPHS) module as its source of thermal power. This new version, referred to as the Step‐2 GPHS Module, has additional and thicker layers of carbon fiber material (Fine Weaved Pierced Fabric) for increased strength over the original GPHS module. The GPHS uses alpha decay of in the oxide form as the primary source of heat, and small amounts of other actinides are also present in the oxide fuel. Criticality calculations have been performed by previous researchers on the original version of the GPHS module (Step 0). This paper presents criticality calculations for the present Step‐2 version. The Monte Carlo N‐Particle eXtended code (MCNPX) was used for these calculations. Numerous configurations of GPHS module arrays surrounded by wet sand and other materials (to reflect the neutrons back into the stack with minimal absorption) were modeled. For geometries with eight GPHS modules (from a single MMRTG) surrounded by wet sand, the configuration is extremely sub‐critical; is about 0.3. It requires about 1000 GPHS modules (from 125 MMRTGs) in a close‐spaced stack to approach criticality when surrounded by wet sand. The effect of beryllium in the MMRTG was found to be relatively small.
Criticality Calculations for Step‐2 GPHS Modules
SPACE TECHNOLOGY AND APPLICATIONS INTERNATIONAL FORUM‐STAIF 2008: 12th Conference on Thermophysics Applications in Microgravity; 1st Symposium on Space Resource Utilization; 25th Symposium on Space Nuclear Power and Propulsion; 6th Conference on Human/Robotic Technology and the Vision for Space Exploration; 6th Symposium on Space Colonization; 5th Symposium on New Frontiers and Future Concept ; 2008 ; Albuquerque (New Mexico)
AIP Conference Proceedings ; 969 , 1 ; 452-457
21.01.2008
6 pages
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
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