Abstract
An assessment carried out some years ago indicated that cermet fuels might provide the high burn-up and integrity required for fast reactors. An irradiation programme was started at Harwell on (U, Pu)O{sub 2} -SS cermet plates and rods, mainly In thermal neutron fluxes, to gain experience of dimensional stability at temperatures typical of modern sodium-cooled fast reactor designs (600-650 Degree-Sign C). A subsequent assessment showed that cermets carried a large penalty as far as breeding was concerned and (U, Pu)C was chosen by Harwell for long-term study as an alternative, economic, fast reactor fuel. However, the results from the cermet experiments were of sufficient promise to proceed with parallel irradiation programmes on cermets and carbide. The studies of cermets showed that dimensional instability (swelling and cladding rupture) were caused by the pressures exerted on the steel matrix by the fuel particles, and that the initial density of the fuel particles was important in determining the burn-up at which failure occurred. Further, it was shown that cermets provided a useful vehicle for studying the changes occurring in oxide fuel particles with increasing burn-up. The disappearance of initial porosity and its replacement by fission gas bubbles and segregated solid fission products was
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Citation Formats
Frost, B. R.T., and Wait, E.
Irradiation Experiments on Plutonium Fuels for Fast Reactors.
IAEA: N. p.,
1967.
Web.
Frost, B. R.T., & Wait, E.
Irradiation Experiments on Plutonium Fuels for Fast Reactors.
IAEA.
Frost, B. R.T., and Wait, E.
1967.
"Irradiation Experiments on Plutonium Fuels for Fast Reactors."
IAEA.
@misc{etde_22117144,
title = {Irradiation Experiments on Plutonium Fuels for Fast Reactors}
author = {Frost, B. R.T., and Wait, E.}
abstractNote = {An assessment carried out some years ago indicated that cermet fuels might provide the high burn-up and integrity required for fast reactors. An irradiation programme was started at Harwell on (U, Pu)O{sub 2} -SS cermet plates and rods, mainly In thermal neutron fluxes, to gain experience of dimensional stability at temperatures typical of modern sodium-cooled fast reactor designs (600-650 Degree-Sign C). A subsequent assessment showed that cermets carried a large penalty as far as breeding was concerned and (U, Pu)C was chosen by Harwell for long-term study as an alternative, economic, fast reactor fuel. However, the results from the cermet experiments were of sufficient promise to proceed with parallel irradiation programmes on cermets and carbide. The studies of cermets showed that dimensional instability (swelling and cladding rupture) were caused by the pressures exerted on the steel matrix by the fuel particles, and that the initial density of the fuel particles was important in determining the burn-up at which failure occurred. Further, it was shown that cermets provided a useful vehicle for studying the changes occurring in oxide fuel particles with increasing burn-up. The disappearance of initial porosity and its replacement by fission gas bubbles and segregated solid fission products was studied in some detaiL No significant differences were observed between UO{sub 2} and(U,Pu)O{sub 2} particles. The initial studies of (U, Pu)C were concerned with the effect of varying composition and structure on swelling and fission gas release. A tantalum-lined nickel alloy cladding material was used to contain both pellet and powder specimens In an irradiation experiment in the core of the Dounreay fast reactor. This showed that the presence of a metal phase in the fuel led to a high swelling rate, that fission gas release was low up to {approx} 3% bum-up, and that a low density powder accommodated the swelling without excessive straining of the can. A subsequent experiment was conducted in a thermal neutron flux to a mean burn-up in excess of 10% burn-up but with a low fuel centre temperature (< 900 Degree-Sign C). Under these conditions gas release was low and fuel swelling was sufficiently low to avoid can failure, in contrast with other results at the same burn-up but at higher fuel centre temperatures ({approx} 1300 Degree-Sign C) where gas release and swelling were both considerably higher. Further experiments are in progress to determine more accurately the rate of swelling of (U, Pu)C in a fast neutron flux and to study possible methods of prolonging the life of carbide fuel elements. These studies are supported by basic investigations of swelling and fission gas release mechanisms. An assessment of the chemical state of the fuel fission products and cladding after irradiation to high burn-up is presented. The analysis is based on the thermodynamics of the system and experimental observations on irradiated fuel material. The systems considered are uranium/plutonium oxide and uranium/plutonium carbides. The principal conclusions of the analysis are that, in oxides, the oxygen potential of the system increases with increasing burn-up and, in carbides, the carbon activity of die irradiated system is maintained at some value between that of the monocarbide and sesquicarbide. (author)}
place = {IAEA}
year = {1967}
month = {Sep}
}
title = {Irradiation Experiments on Plutonium Fuels for Fast Reactors}
author = {Frost, B. R.T., and Wait, E.}
abstractNote = {An assessment carried out some years ago indicated that cermet fuels might provide the high burn-up and integrity required for fast reactors. An irradiation programme was started at Harwell on (U, Pu)O{sub 2} -SS cermet plates and rods, mainly In thermal neutron fluxes, to gain experience of dimensional stability at temperatures typical of modern sodium-cooled fast reactor designs (600-650 Degree-Sign C). A subsequent assessment showed that cermets carried a large penalty as far as breeding was concerned and (U, Pu)C was chosen by Harwell for long-term study as an alternative, economic, fast reactor fuel. However, the results from the cermet experiments were of sufficient promise to proceed with parallel irradiation programmes on cermets and carbide. The studies of cermets showed that dimensional instability (swelling and cladding rupture) were caused by the pressures exerted on the steel matrix by the fuel particles, and that the initial density of the fuel particles was important in determining the burn-up at which failure occurred. Further, it was shown that cermets provided a useful vehicle for studying the changes occurring in oxide fuel particles with increasing burn-up. The disappearance of initial porosity and its replacement by fission gas bubbles and segregated solid fission products was studied in some detaiL No significant differences were observed between UO{sub 2} and(U,Pu)O{sub 2} particles. The initial studies of (U, Pu)C were concerned with the effect of varying composition and structure on swelling and fission gas release. A tantalum-lined nickel alloy cladding material was used to contain both pellet and powder specimens In an irradiation experiment in the core of the Dounreay fast reactor. This showed that the presence of a metal phase in the fuel led to a high swelling rate, that fission gas release was low up to {approx} 3% bum-up, and that a low density powder accommodated the swelling without excessive straining of the can. A subsequent experiment was conducted in a thermal neutron flux to a mean burn-up in excess of 10% burn-up but with a low fuel centre temperature (< 900 Degree-Sign C). Under these conditions gas release was low and fuel swelling was sufficiently low to avoid can failure, in contrast with other results at the same burn-up but at higher fuel centre temperatures ({approx} 1300 Degree-Sign C) where gas release and swelling were both considerably higher. Further experiments are in progress to determine more accurately the rate of swelling of (U, Pu)C in a fast neutron flux and to study possible methods of prolonging the life of carbide fuel elements. These studies are supported by basic investigations of swelling and fission gas release mechanisms. An assessment of the chemical state of the fuel fission products and cladding after irradiation to high burn-up is presented. The analysis is based on the thermodynamics of the system and experimental observations on irradiated fuel material. The systems considered are uranium/plutonium oxide and uranium/plutonium carbides. The principal conclusions of the analysis are that, in oxides, the oxygen potential of the system increases with increasing burn-up and, in carbides, the carbon activity of die irradiated system is maintained at some value between that of the monocarbide and sesquicarbide. (author)}
place = {IAEA}
year = {1967}
month = {Sep}
}