Uranium nitride-silicide advanced nuclear fuel: higher efficiency and greater safety

AbstractRecent interest in compact nuclear reactors for applications in space or in remote locations drives innovation in nuclear fuel design, especially non-oxide ceramic nuclear fuels. This work details neutronic modeling designed to support the development of a new nuclear fuel concept based on a mixture of thorium and uranium nitride. A Monte Carlo N-Particle Version 6.2 (MCNP-6) model of a compact 10 MWe reactor design which incorporates (ThxU1−x)N fuel is presented. In this context, a “compact” reactor is a completely assembled reactor which may be emptied of coolant and transported by specialized commercial vehicle, deployed by a C130J aircraft, or launched into space. Core geometry, reflector barrels, and the heat exchange zones are designed to support reduction of overall reactor volume of core components while maintaining criticality with a fixed total fuel mass of 4500 kg. Dense mixed nitrides of thorium nitride (ThN) additions in uranium nitride (UN) in 5 wt.% increments between $$0.05 \le x \le 0.5$$ 0.05 ≤ x ≤ 0.5 have been considered for calculation of $$k_{\infty }$$ k ∞ and $$k_{{{\text{effective}}}}$$ k effective . ThN additions in UN results in a slight increase in the magnitude of the temperature coefficient of reactivity, which is negative by design. The isotopic distribution of the principal actinide inventory as a function of burnup, time, and initial fuel composition is presented and discussed within the context of the proliferation risk of this core design.

Download Full-text

Thermal Aspects of Using Uranium Nitride in SuperCritical Water-Cooled Nuclear Reactors

18th International Conference on Nuclear Engineering: Volume 2 ◽

10.1115/icone18-29790 ◽

2010 ◽

Cited By ~ 1

Author(s):

Lisa Grande ◽

Wargha Peiman ◽

Sally Mikhael ◽

Bryan Villamere ◽

Adrianexy Rodriguez-Prado ◽

...

Keyword(s):

Nuclear Fuel ◽

Supercritical Water ◽

Nuclear Reactors ◽

Inlet Temperature ◽

Outlet Temperature ◽

Bulk Fluid ◽

Inconel 600 ◽

Uranium Nitride ◽

Axial Heat ◽

Centerline Temperature

SuperCritical Water-cooled nuclear Reactors (SCWRs) utilize a light-water coolant pressurized to 25 MPa with a channel inlet temperature of 350°C and outlet temperature of 625°C. Previous studies have indicated that uranium dioxide (UO2) nuclear fuel may not be suitable for SCWR use, because the maximum fuel centerline temperature might exceed the industry accepted limit of 1850°C. This research paper explores the use of uranium nitride (UN) as an alternative fuel option to UO2 at SuperCritical Water (SCW) conditions. A generic 1200-MWel Pressure-Tube (PT) -type reactor cooled with SCW was used for this thermalhydraulics analysis. The selected fuel option must have a fuel centerline temperature not higher than the industry accepted limit of 1850°C. Furthermore, the sheath (clad) temperature must not exceed the design limit of 850°C. The sheath and bundle geometry were adopted from previous studies. A single fuel channel was modeled using the UN fuel and an Inconel-600 sheath for several Axial Heat Flux Profiles (AHFPs). Uniform, upstream-skewed cosine, cosine and downstream-skewed cosine AHFPs were used. For each AHFP bulk-fluid, sheath and fuel centerline temperatures, and Heat Transfer Coefficient (HTC) profiles were calculated along the heated length of the channel. The calculations show that the UN fuel maintains a centerline temperature well below the industry accepted limit due to its high thermal conductivity at high temperatures. Therefore, the UN nuclear fuel is a viable fuel option for PT-type SCWRs.

Download Full-text

Opening of Nitride Spent Nuclear Fuel

KnE Materials Science ◽

10.18502/kms.v6i1.8122 ◽

2020 ◽

Author(s):

Alexei Potapov ◽

Kirill Karimov ◽

Mikhail Mazannikov ◽

Vladimir Shishkin ◽

Yury Zaykov

Keyword(s):

Nuclear Fuel ◽

Spent Nuclear Fuel ◽

Electrochemical Process ◽

Electrochemical Dissolution ◽

Oxide Fuel ◽

Fuel Rods ◽

Promising Alternative ◽

Nitride Fuel ◽

Oxide Nuclear Fuel ◽

Uranium Nitride

Nitride nuclear fuel (UN + 10-20% PuN) is considered a promising alternative to the widely used oxide nuclear fuel (UO2). Thermal conductivity and density of nitride fuel are ∼ 7 times and 1.3 times higher than that of oxide fuel, respectively. Nitride fuel demonstrates a good compatibility with the cladding of fuel rods made of stainless steel. Along with the development of new fuel, methods for its subsequent processing are being developed. Various options for the initial opening of nitride spent nuclear fuel (SNF) are considered in this article. The use of gaseous chlorine is technologically inconvenient and dangerous when working with radioactive substances. The electrochemical dissolution of nitride SNF cannot be realized due to the formation of a by-product - UNCl. Uranium nitride chloride is an insulator and it blocks the electrochemical process. It was found that the chlorination of nitride SNF with cadmium or lead chlorides makes it possible to carry out 100% UN → UCl3 conversion. The use of voloxidation (oxidation of nitride SNF to oxides) as the first stage of processing will make the entire technology universal, suitable for processing both nitride and oxide SNF. The choice of the method for opening SNF depends on the choice of the subsequent stages of its processing. Keywords: nitride spent nuclear fuel, SNF, chlorination, anodic dissolution, UNCl, “soft” chlorination, voloxidation, processing

Download Full-text