Lightweight Radioisotope Heater Unit (LWRHU) Production Qualification Impact Test

Technical Report · Thu May 01 04:00:00 EDT 1997

DOI:https://doi.org/10.2172/1083156· OSTI ID:1083156

Reimus, Mary Ann H. ^[1]; Rinehart, Gary H. ^[1]

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1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

The lightweight radioisotope heater unit (LWRHU), a ²³⁸PuO₂-fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed ²³⁸PuO₂ fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, a post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. The fuel fragmentation observed in the Cassini LWRHU, however, was superior to that of the Galileo unit. The fuel fragmentation distribution spread was much greater, and the weight fraction of ≤45-µm fines generated was an order of magnitude greater for the Galileo unit.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• DOE Contract Number: AC52-06NA25396; W-7405-ENG-36
• OSTI ID: 1083156
• Report Number(s): LA--13311-MS
• Country of Publication: United States
• Language: English

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