Release of Radioactive Materials in Simulation Tests of a Postulated Solvent Fire in a Nuclear Fuel Reprocessing Plant

Nishio, Gunji; Hashimoto, Kazuichiro

doi:10.13182/nt89-a34305

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…To quantify the risk of radioactive material resuspension from a TBP solvent set on fire, some experiments have been carried out − but, with the exception of Mishima et al who studied fractional release from heating plutonium nitrate solution without TBP, no other experiment with plutonium was conducted due to the critical safety constraints. The main experimental results are gathered in Table , leaving out the tests involving ruthenium, because the possible formation of RuO 4(g) may significantly alter the measured fractional release with respect to other radioactive materials.…”

Section: Introductionmentioning

confidence: 99%

“…Some other tests were performed in the presence of some FPs (Ru, Cs, and Sr) in the acid phase with quite low concentrations (total smaller than 2.5 g/L) and suggest a release of uranium but without any convincing supporting arguments. Nishio and Hashimoto conducted some tests with uranium and some FPs and measured a low fractional release, smaller than 0.1% for U. In addition, they have analyzed their experimental data on the basis of a physical modeling of the phenomena involved but it appears that the phenomenology is complex and many model parameters are either fitted to experiments or calculated from empirical relationships.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Study of Plutonium(IV) Complexes Formed within the PUREX Process: A Proposal of a Plutonium Surrogate in Fire Conditions

2014

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We present a relativistic quantum chemical study to determine the best surrogate for plutonium(IV) to be used in experimental investigations of the behavior of plutonium-nitrate-TBP in fire conditions that might occur in the nuclear fuel refining process known as PUREX. In this study geometries and stabilities of Pu(NO3)6(2-) and Pu(NO3)4(TBP)2 complexes were compared to that of equivalent complexes of selected elements from the lanthanide and actinide series (Ce, Th, U) chosen on the basis of similar ionic radii and stability as tetravalent species. PBE and PBE0 DFT functionals have proven to be sufficient and affordable for qualitative studies, performing as good as the wave function based correlated method MP2. On the basis of our results, cerium(IV) appears to be a good surrogate for plutonium(IV).

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical Study of Plutonium(IV) Complexes Formed within the PUREX Process: A Proposal of a Plutonium Surrogate in Fire Conditions

2014

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“…As previously mentioned, cerium(IV) has been largely considered in previous studies for investigating airborne release of plutonium during accidental fires. From an experimental point of view, among six studies summarized by Quintiere for fires involving liquid fuels, three have been carried out by considering cerium(IV) as a surrogate. − However, cerium(IV) is known for its high oxidizing power and could potentially be reduced to cerium(III) during or after extraction and fire, which would not be truly representative of plutonium(IV) behavior. Then, the question of its relevance as a plutonium(IV) surrogate, in terms of airborne release in the event of a fire, representative of the PUREX process, is still under consideration.…”

Section: Introductionmentioning

confidence: 99%

Influence of Light and Temperature on the Extractability of Cerium(IV) as a Surrogate of Plutonium(IV) and its Effect on the Simulation of an Accidental Fire in the PUREX Process

et al. 2019

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Modeling of plutonium(IV) behavior during an accidental fire in a reprocessing plant was considered using various non-radioactive metallic surrogates. Among those elements, cerium(IV) was supposed to be a suitable candidate due to possible formation of a complex with TPB, but its extractability and stability have not been studied previously under representative plutonium uranium reduction extraction (PUREX) conditions. In this work, we investigated the chemical analogy between cerium(IV) and plutonium(IV) in this extractive process and combustion thereof. Distribution ratios are reported for acidities of 1–4 mol L –1 in equal volumes of nitric acid and a 30:70 mixture of tributylphosphate and hydrogenated tetrapropylene. The influences of light, temperature, and extraction time were studied by UV–vis spectroscopy. The results showed that cerium(IV) is extracted quantitatively but is reduced over time to cerium(III) in the organic mixture. Spectrophotometric investigations of this reaction kinetics revealed an apparent rate constant k of 0.021 ± 0.002 mol 0.5 L 0.5 min –1 at 298 K and an apparent fractional reaction order of 0.5. The activation energy of this reduction was found to be around 82 ± 2 kJ mol –1 by the Arrhenius plot method. The combustion of mono- and biphasic solutions prepared with a cerium(IV) concentration of 10 g L –1 revealed that the extracted complexes, Ce 2 O·6NO 3 ·3TBP (org) or Ce 4 O 4 ·8NO 3 ·6TBP (org) , are reduced during the combustion. Compositions of the resulting ashes and soot were analyzed and highlighted the presence of pyrophosphates and polycyclic aromatic hydrocarbons, with some traces of cerium. Ce(IV) is not suitable to represent Pu(IV) from a chemical point of view in HNO 3 /TBP–HTP solutions.

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Airborne Release Fraction of Dissolved Materials During the Combustion of Liquids Representative of Nuclear Waste Treatment Process

et al. 2022

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Release of Radioactive Materials in Simulation Tests of a Postulated Solvent Fire in a Nuclear Fuel Reprocessing Plant

Cited by 6 publications

References 10 publications

Theoretical Study of Plutonium(IV) Complexes Formed within the PUREX Process: A Proposal of a Plutonium Surrogate in Fire Conditions

Theoretical Study of Plutonium(IV) Complexes Formed within the PUREX Process: A Proposal of a Plutonium Surrogate in Fire Conditions

Influence of Light and Temperature on the Extractability of Cerium(IV) as a Surrogate of Plutonium(IV) and its Effect on the Simulation of an Accidental Fire in the PUREX Process

Airborne Release Fraction of Dissolved Materials During the Combustion of Liquids Representative of Nuclear Waste Treatment Process

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