An assessment of the thermodynamic properties of uranium nitride, plutonium nitride and uranium-plutonium mixed nitrides

Commission of the European Communities
nuclear science
and technology
An assessment
of the thermodynamic properties
of uranium nitride, plutonium nitride
and uranium-plutonium mixede Commission of the European Communities
nuclear science
and technology
An assessment
of the thermodynamic properties
of uranium nitride, plutonium nitride
and uranium-plutonium mixed e
Tsuneo Matsui1 and R.W. Ohse
Commission of the European Communities
Joint Research Centre
European Institute for Transuranium Elements,
Postfach 2340, D-7500 Karlsruhe
1 On leave of absence from Nagoya University,
Department of Nuclear Engineering,
Faculty of Engineering,
Furo-cho, Chikusa-ku, Nagoya 464, Japan
ΡΑΠΙ. ΠΓ'\ nifetøh.
Directorate-General for Science, Research and Deve opmeot
Joint Research Centre ifJ.C
¿EUR 108B8~EÑ" 1986 Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
Bâtiment Jean Monnet
LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on
behalf of then is responsible for the use which might be made of the
following information
Cataloguing data can be found at the end of this publication
Luxembourg: Office for Official Publications of the European Communities, 1987
ISBN 92-825-6842-3 Catalogue number: CD-NA-10858-EN-C
© ECSC-EEC-EAEC. Brussels · Luxembourg, 1987
Printed in Belgium Contents
List of figures
List of tables VII
1 1. Introduction
1 2. Phase diagram
1 2.1 U - Ν system
5 2.2 Pu - Ν system
5 2.3 U - Pu - Ν system
10 3. Vapour pressure
10 3.1 UN
18 3.2 PuN
28 3.3 (U,Pu)N
37 Heat capacity 4.
37 4.1 UN
40 PuN 4.2
44 4.3 <U,Pu)N
5 . Enthalpy of formation and free energy of formation 48
5.1 UN 48
5.2PuN58
5.3(U,Pu)N62
626.Summary
72 Acknowle dgement
73
References
III — List of figures
Fig. 1 Phase diagram of the U-N system (after Tagawa [2])
Fig. 2 Phase diagram of the Pu-N system (after HolLeck [29])
Fig. 3 The phase diagram of the ternary U-Pu-N system at 1573K
obtained from the thermodynamic calculation by Potter [4]
Fig. 4 Dependence of lattice constant of (U,Pu)N on composition
(after Tennery and Bomar [15])
Fig. 5 Vapour pressures of N2(g), U(g) and UN(g) over UN
(with trace U( I ) )
Fig. 6 Vapour pressures over UN(l) above melting point
Fig. 7 Vapour pressures of U ( g ) and N2(g) for the U-UN1.5
system at 1600K
Fig. 8 Vapour pressures over PuN(s), Pu(l) + PuN(s) and Pu(l)
Fig. 9 Vapour pressures over PuN(l) above melting point
— V — Fig. 10 Vapour pressures of Pu(g) and N2(g) for the Pu-PuN
system at 2000K
Fig. 11 Vapour pressures over ( Uo.ePuo.2) Ν ( s )
Fig. 12 Vapour pressures over ( U0.ePu0.2) Ν ( L )
Fig. 13 Compositional dependence of vapour pressures in the
system UN-PuN, where N/(U+Pu) = 1
Fig. 14 Heat capacity of UN
Fig. 15 Heat capacity of PuN
Fig. 16 Heat capacity of (U0.ePu0.2)N
Fig. 17 Vapour pressures of the main gas species and total
pressures over UN(s), PuN(s) and ( U0.ePu0.2) Ν ( s )
Fig. 18 Heat capacities of UN, PuN and (U0.BPU0.2>N
■VI — List of tables
Table 1 Homogeneity range of UN
Table 2 Melting temperature and decomposition pressure of UN
Table 3 Melting temperature of (U0.ePuo.2)N
Table 4 Equations for the vapour pressures over UN
Table 5 Vapour pressures over UN(s), unit: log (P/MPa)
Table 6 Vapour pressures over UNCI), unit: log (P/MPa)
Table 7 Equations for the vapour pressures over PuN
Table 8 Vapour pressures over PuN(s), unit: log CP/MPa)
Table 9 Vapour pressures over PuN(l), unit: log (P/MPa'»
Table 10 Vapour pressures over ( Uo.ePuo.2) Ν [49]
Table 11 Equations for the vapour pressures over (UD.ePuo.2)N
Table 12 Vapour pressures over ( U0.ePuo.2) Ν ( s ) , unit: log(P/MPa)
Table 13 Vapour pressures over ( U0.8Pu0.2> Ν ( I ) , unit: log(P/MPa)
Table 14 Estimated vapour pressure of (U0.ePuo.2>N from ideal
solution assumption and experimental data, unit: log
(P/MPa)
Table 15 Debye temperatures
Table 16 High temperature heat capacity and enthalpy of UN
— VII — Table 17 Thermal functions for UN
Table 18 Thermal functions for PuN based on the heat capacity
data by Oett ing [12]
Table 19 Thermal functions for PuN based on the heat capacity
data by Alexander et al. [11]
Table 20 Thermal functions for (U0.ePuo.2)N based on ideal
solution assumption
Table 21 Thermal functions for (Uo.ePu0.2)N based on the heat
capacity data by Alexander et al.[11]
Table 22 Enthalpy of formation for UN(s)
Table 23 Thermal functions for U(s,L) [14]
Table 24 Thermals for N2(g) [67]
Table 25 Thermodynamic functions for the formation of UN(s)
Table 26 Gibbs energies of formation
Table 27 Enthalpy of formation for PuN(s)
Table 28 Thermal functions for Pu(s,l) [14]
Table 29 Thermodynamic functions for the formation of PuN(s)
Table 30c functions for the formation of PuN(s)
Table 31 Thermodynamic functions for the formation of
(Uo.ePuo.2)N based on ideal solution assumption
Table 32c functions for the formation of
(Uo.sPuo.2)N based on the experimental data by
Alexander et a I .· [ 1 1 ]
Table 33 Summary of the crystal structure and the t hermochem i ca I
properties of UN, PuN and (U0.ePuo.2)N
— VIII —