The Melt Refining of Irradiated Uranium: Application to EBR-II Fast Reactor Fuel. XI. Behavior of Iodine in Melt Refining

Regulatory Technology Development Plan - Sodium Fast Reactor. Mechanistic Source Term - Metal Fuel Radionuclide Release

“…During the late 1950s, in parallel to the reprocessing experimentation being conducted at EBR-II, several research institutions (Oak Ridge National Laboratory -ORNL, Hanford, and Atomics International -AI) were conducting fuel-melting tests to determine fission product volatilization during reactor accidents. While many of these experiments focused on fission product release when different types of uranium metal fuel were oxidized, which is unlikely to occur during a metal fuel, pool-type SFR core damage accident 4 , other tests investigated fission product volatilization in inert atmospheres. As mentioned in the preceding section, release fractions determined by volatilization of fission products into an inert gas may underestimate the release of radionuclides from metal fuel into sodium during an SFR accident, as some radionuclides may be soluble in sodium in their solid or liquid states.…”

Regulatory Technology Development Plan Sodium Fast Reactor. Mechanistic Source Term Development

“…sodium to form NaI [51] [56]. Experimentation with melting of an U-Fs alloy in a crucible for four hours at 1250°C resulted in the release of only ~1% of the iodine from the fuel 18 [57]. Only when held at higher temperatures (≥1300°C) for multiple hours were significant fractions of the iodine released from the fuel [57].…”

“…This is especially true for 132 Te, which decays to 132 I, a strong gamma emitter [41]. In past experiments, melting U-Fs alloy in a crucible for three hours at 1400°C, which is well above the melting point for metal fuel, 98.1% of the tellurium was retained in the fuel [71]. This high retention is in agreement with past SFR metal fuel accidents, where no tellurium has been found released from the fuel, even with significant melting (described in Section 4.3).…”

“…However, these melting points may be lower when the elements are mixed with uranium, as is the case for ruthenium [72]. Even so, experimentation has not observed significant releases, as melting of U-Fs alloys in a crucible to temperatures of 1200-1400°C, which is well above the melting point of metal fuel, for five hours showed almost complete retention of Ru, Mo, Rh, and Pd within the fuel [71] 23 . 23 Technetium, examined in a separate experiment, was expected to act in a similar way by the authors of [70].…”