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Title: Study of the U{sub 3}O{sub 8} effect on MOX fuel sintering mechanisms

Abstract

The manufacturing of uranium-plutonium mixed oxides fuel (also known as MOX) for light water reactor (LWR), starting generally from UO{sub 2} and PuO{sub 2} raw powders and resulting in (U,Pu)O{sub 2} pellets, involves several steps: i) preparation of a UO{sub 2}+PuO{sub 2} master blend with a Pu content of about 25-30 at% by milling and sieving, ii) dilution by mixing the master blend with non-milled UO{sub 2} to reach a Pu content of about 10 at%, iii) pressing and iv) sintering under Ar / 4 % H{sub 2} + H{sub 2}O gas mixture. In this paper, triuranium octoxide (U{sub 3}O{sub 8}) is used as an additional raw powder in the LWR MOX fuel manufacturing. One of the objectives of this work is to understand the sintering behavior of U{sub 3}O{sub 8} under Ar / 4 % H{sub 2} + H{sub 2}O gas mixture and its effect when added to a UO{sub 2}-PuO{sub 2} mixture. A special attention is given on U{sub 3}O{sub 8} reduction, phase transitions, redox reactions and oxygen partial pressure (pO{sub 2}) evolution during shrinkage: the impact of these phenomena on the densification kinetics is discussed, especially the de-densification phenomenon which could occur at high temperature. For thatmore » purpose a specific dilatometer, coupled with a zirconia probe implemented at furnace inlet and outlet has been used which allows following continuously and simultaneously the fuel shrinkage and the oxygen partial pressure variation as a function of temperature. The experiments have shown that, contrary to UO{sub 2}, the sintering of milled PuO{sub 2} is accompanied by a de-densification at high temperature. This de-densification phenomenon already occurs with co-milled 71 at% UO{sub 2} + 29 at% PuO{sub 2}, but with a smaller magnitude. When pure milled U{sub 3}O{sub 8} is sintered, no de-densification phenomenon is observed but the low density of the sintered pellet could hide such a phenomenon. The incorporation of U{sub 3}O{sub 8} into a UO{sub 2}-PuO{sub 2} master blend containing 29 at% of plutonium leads to an exacerbation of the de-densification phenomenon with a higher loss on ignition suggesting that U{sub 3}O{sub 8} contributes also to the de-densification phenomenon. This could be due to high temperature reactions involving the initial carbon content of the raw U{sub 3}O{sub 8} powder. (authors)« less

Authors:
;  [1];  [2]
  1. CEA DEN DTEC SECA, Cadarache, F-131 (France)
  2. CNRS, ICMCB-CNRS, UPR 9048, F-3360, Pessac (France)
Publication Date:
Research Org.:
American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
OSTI Identifier:
22764096
Resource Type:
Conference
Resource Relation:
Conference: TOP FUEL 2016: LWR fuels with enhanced safety and performance, Boise, ID (United States), 11-15 Sep 2016; Other Information: Country of input: France; 10 refs.; This record replaces 50007242; Related Information: In: TOP FUEL 2016 Proceedings| 1670 p.
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 36 MATERIALS SCIENCE; CARBON; FUEL PELLETS; MANUFACTURING; MIXED OXIDE FUELS; MIXTURES; OXYGEN; PARTIAL PRESSURE; PLUTONIUM; PLUTONIUM OXIDES; POWDERS; PRESSING; REDOX REACTIONS; SINTERING; TEMPERATURE RANGE 0400-1000 K; URANIUM; URANIUM DIOXIDE; URANIUM OXIDES U3O8; WATER COOLED REACTORS; WATER MODERATED REACTORS; ZIRCONIUM OXIDES

Citation Formats

Chambon, C., Vaudez, S., Heintz, J. M., and Bordeaux INP, ICMCB, UPR 9048, F-3360, Pessac. Study of the U{sub 3}O{sub 8} effect on MOX fuel sintering mechanisms. United States: N. p., 2016. Web.
Chambon, C., Vaudez, S., Heintz, J. M., & Bordeaux INP, ICMCB, UPR 9048, F-3360, Pessac. Study of the U{sub 3}O{sub 8} effect on MOX fuel sintering mechanisms. United States.
Chambon, C., Vaudez, S., Heintz, J. M., and Bordeaux INP, ICMCB, UPR 9048, F-3360, Pessac. Fri . "Study of the U{sub 3}O{sub 8} effect on MOX fuel sintering mechanisms". United States.
@article{osti_22764096,
title = {Study of the U{sub 3}O{sub 8} effect on MOX fuel sintering mechanisms},
author = {Chambon, C. and Vaudez, S. and Heintz, J. M. and Bordeaux INP, ICMCB, UPR 9048, F-3360, Pessac},
abstractNote = {The manufacturing of uranium-plutonium mixed oxides fuel (also known as MOX) for light water reactor (LWR), starting generally from UO{sub 2} and PuO{sub 2} raw powders and resulting in (U,Pu)O{sub 2} pellets, involves several steps: i) preparation of a UO{sub 2}+PuO{sub 2} master blend with a Pu content of about 25-30 at% by milling and sieving, ii) dilution by mixing the master blend with non-milled UO{sub 2} to reach a Pu content of about 10 at%, iii) pressing and iv) sintering under Ar / 4 % H{sub 2} + H{sub 2}O gas mixture. In this paper, triuranium octoxide (U{sub 3}O{sub 8}) is used as an additional raw powder in the LWR MOX fuel manufacturing. One of the objectives of this work is to understand the sintering behavior of U{sub 3}O{sub 8} under Ar / 4 % H{sub 2} + H{sub 2}O gas mixture and its effect when added to a UO{sub 2}-PuO{sub 2} mixture. A special attention is given on U{sub 3}O{sub 8} reduction, phase transitions, redox reactions and oxygen partial pressure (pO{sub 2}) evolution during shrinkage: the impact of these phenomena on the densification kinetics is discussed, especially the de-densification phenomenon which could occur at high temperature. For that purpose a specific dilatometer, coupled with a zirconia probe implemented at furnace inlet and outlet has been used which allows following continuously and simultaneously the fuel shrinkage and the oxygen partial pressure variation as a function of temperature. The experiments have shown that, contrary to UO{sub 2}, the sintering of milled PuO{sub 2} is accompanied by a de-densification at high temperature. This de-densification phenomenon already occurs with co-milled 71 at% UO{sub 2} + 29 at% PuO{sub 2}, but with a smaller magnitude. When pure milled U{sub 3}O{sub 8} is sintered, no de-densification phenomenon is observed but the low density of the sintered pellet could hide such a phenomenon. The incorporation of U{sub 3}O{sub 8} into a UO{sub 2}-PuO{sub 2} master blend containing 29 at% of plutonium leads to an exacerbation of the de-densification phenomenon with a higher loss on ignition suggesting that U{sub 3}O{sub 8} contributes also to the de-densification phenomenon. This could be due to high temperature reactions involving the initial carbon content of the raw U{sub 3}O{sub 8} powder. (authors)},
doi = {},
url = {https://www.osti.gov/biblio/22764096}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2016},
month = {7}
}

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