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In-pile measurement of the thermal conductivity of irradiated metallic fuel

Conference · · Transactions of the American Nuclear Society; (United States)
OSTI ID:7056042
;  [1]
  1. Argonne National Lab., IL (United States)
Reliable knowledge of thermal conductivity is needed to assess reactor fuel performance. In normal operation, fuel pin linear power and fuel thermal conductivity together largely determine the fuel's peak temperature, and under severe accident conditions, fuel thermal conductivity largely determines the power to melt. Unfortunately, assessing the thermal conductivity of modern high-swelling sodium-bonded metallic fuel is neither theoretically straightforward nor amenable to laboratory measurements. At issue is whether the high swelling that takes place in metallic fuel during the first few atomic percent of burnup could lead to drastic conductivity reductions by factors of as much as 0.4 to 0.5. Such reduction may be mitigated by the infiltration of fuel porosity by high-conductivity liquid bond sodium or later by the solid and liquid fission products that accumulate with burnup. In this paper, the authors utilize measurements of maximum melting from intact irradiated metal fuel pins tested in the recent M-series in-pile test program in TREAT to estimate metal fuel thermal conductivity directly and in situ. Of six irradiated integral fast reactor prototype fuel pins ubjected to severe overpower and melting, four pins remained intact. Three of the test pins were of ternary alloy (U-19 Pu-10 Zr) and one of binary (U-10 Zr) alloy. Importantly, these test pins span key range of low burnup where minimum values of conductivity would be expected.
OSTI ID:
7056042
Report Number(s):
CONF-920606--
Conference Information:
Journal Name: Transactions of the American Nuclear Society; (United States) Journal Volume: 65
Country of Publication:
United States
Language:
English