Nitride fuel for Gen IV nuclear power systems

Abstract

Nuclear energy has been a part of the energy mix in many countries for decades. Today in principle all power producing reactors use the same techniqe. Either PWR or BWR fuelled with oxide fuels. This choice of fuel is not self evident and today there are suggestions to change to fuels which may be safer and more economical and also used in e.g. Gen IV nuclear power systems. One such fuel type is the nitrides. The nitrides have a better thermal conductivity than the oxides and a similar melting point and are thus have larger safety margins to melting during operation. In addition they are between 30 and 40% more dense with respect to fissile material. Drawbacks include instability with respect to water and a sometimes complicated fabrication route. The former is not really an issue with Gen IV systems but for use in the present fleet. In this paper we discuss both production and recycling potential of nitride fuels.

Materials for Sustainable Nuclear Energy: A European Strategic Research and Innovation Agenda for All Reactor Generations

“…Reactor fuels are based on compounds of one or more fissile and/or fertile nuclides, mainly of U and Pu. They can be either refractory oxides, typically U oxides and MOX, which are also used in current generation reactors [106][107][108][109], or other ceramics, such as carbides [110], nitrides [111,112] and silicides [107,113,114], as well as metallic alloys [115]. Other fuel concepts consider ceramic/ceramic or ceramic/metal composites [116], as well as fluid molten salt fuels [117].…”

“…They have similar melting point as MOX, but higher thermal conductivity. This enables operation with a larger margin to melting (safety margin) or with a higher linear power (economic gain) compared to oxide fuel [110,112]. However, achieving high purities in these fuels poses some challenges in the fabrication process [112].…”

Review of fuel assembly design in lead‐based fast reactors and research progress in fuel assembly of China initiative accelerator driven system

“…As an advanced fuel, nitride fuel has the advantages of high thermal conductivity, high metal atom density, good radiation stability, good chemical compatibility with most candidate cladding materials, and easy dissolution in nitric acid for reprocessing. However, considerable parasitic neutron absorption and formation of the environmentally hazardous 14 C due to the high neutron capture cross section of 14 N results in the use of enriched 15 N, which significantly increases the fuel cost and thus restricts its application 68,69 …”

Features that Further Performance Limits of Nuclear Fuel Fabrication: Opportunities for Additive Manufacturing of Nuclear Fuels

“…Uranium mononitride has a number of highly favorable properties for use as a nuclear fuel. However, processing of UN powders into dense pellets has historically been a historical [11]. Recent efforts have improved on the results obtained using a conventional cold press and pressureless sintering by use of spark plasma sintering (SPS) [12].…”