Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Reactor performance and safety characteristics of ThN-UN fuel concepts in a PWR

Journal Article · · Nuclear Engineering and Design
The reactor performance and safety characteristics of mixed thorium mononitride (ThN) and uranium mononitride (UN) fuels in a pressurized water reactor (PWR) are investigated to discern the potential nonproliferation, waste, and accident tolerance benefits provided by this fuel form. In this paper, we present results from an initial screening of mixed ThN-UN fuels in normal PWR operating conditions and compares their reactor performance to UO2 in terms of fuel cycle length, reactivity coefficients, and thermal safety margin. ThN has been shown to have a significantly greater thermal conductivity than UO2 and UN. Admixture with a UN phase is required because thorium initially contains no fissile isotopes. Results from this study show that ThN-UN mixtures exist that can match the cycle length of a UO2-fueled reactor by using 235U enrichments greater than 5% but less than 20% in the UN phase. Reactivity coefficients were calculated for UO2, UN, and ThN-UN mixtures, and it was found that the fuel temperature and moderator temperature coefficients of the nitride-based fuels fall within the acceptable limits specified by the AP1000 Design Control Document. Reduced soluble boron and control rod worth for these fuel forms indicates that the shutdown margin may not be sufficient, and design changes to the control systems may need to be considered. The neutronic impact of 15N enrichment on reactivity coefficients is also included. Due to the greatly enhanced thermal conductivity of the nitride-based fuels, the UN and ThN-UN fuels provide additional margin to fuel melting temperature relative to UO2.
Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1661259
Alternate ID(s):
OSTI ID: 1776134
OSTI ID: 22893627
Journal Information:
Nuclear Engineering and Design, Journal Name: Nuclear Engineering and Design Journal Issue: 1 Vol. 355; ISSN 0029-5493
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (34)

Nuclear and materials aspects of the thorium fuel cycle journal September 1981
Material property correlations for uranium mononitride journal May 1990
Thermodynamic and Thermophysical Properties of the Actinide Nitrides book January 2012
Critical evaluation of the thermal properties of Th02 and Th1−yUy02 and a survey of the literature data on Th1−yPuy02 journal November 1997
Thermal conductivity of ThO2 and Th0.98U0.02O2 journal January 2000
Long time experience with the development of HTR fuel elements in Germany journal August 2002
Perspectives of the thorium fuel cycle journal March 1998
Fuel residence time in BWRs with nitride fuels journal September 2012
Towards the thorium fuel cycle with molten salt fast reactors journal February 2014
An assessment of thorium and spent LWR-fuel utilization potential in CANDU reactors journal May 2004
Melting of stoichiometric and hyperstoichiometric uranium dioxide journal June 2005
Development of CAP process for fabrication of ThO2–UO2 fuels Part I: Fabrication and densification behaviour journal February 2008
Screening of advanced cladding materials and UN–U3Si5 fuel journal July 2015
Synthesis and sintering of UN-UO2 fuel composites journal November 2015
UO2–UN composites with enhanced uranium density and thermal conductivity journal October 2015
Fabrication and thermophysical property characterization of UN/U3Si2 composite fuel forms journal November 2017
U3Si2 behavior in H2O environments: Part II, pressurized water with controlled redox chemistry journal March 2018
ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology journal December 2006
ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data journal December 2011
Design and development of the AHWR—the Indian thorium fuelled innovative nuclear reactor journal April 2006
Pu recycling in a full Th-MOX PWR core. Part I: Steady state analysis journal January 2011
Neutronic performance of uranium nitride composite fuels in a PWR journal August 2014
Sustainable thorium nuclear fuel cycles: A comparison of intermediate and fast neutron spectrum systems journal August 2015
The thorium molten salt reactor: Moving on from the MSBR journal September 2006
Some Phase Equilibria in the Thorium-Nitrogen System journal January 1967
Feasible Region of Design Parameters for Water Cooled Thorium Breeder Reactor journal July 2007
Breeding Capability and Void Reactivity Analysis of Heavy-Water-Cooled Thorium Reactor journal July 2008
Neutron Spectrum Effects on Burnup, Reactivity, and Isotopics in UO 2 /H 2 O Lattices journal July 2002
Physics Experiments and Lifetime Performance of the Light Water Breeder Reactor journal August 1989
Fabrication and Thermal Conductivity of (Th,U)O 2 Pellets journal July 2004
High-Utilization Lattices for Thorium-Based Fuels in Heavy Water Reactors journal April 2014
Use of Thorium in Light Water Reactors journal August 2005
The Nonproliferative Light Water Thorium Reactor: A New Approach to Light Water Reactor Core Technology journal December 1998
Breeding Capability and Void Reactivity Analysis of Heavy-Water-Cooled Thorium Reactor journal January 2008

Cited By (1)

Direct determination of uranium in sintered deeply depleted uranium oxide pellets by wavelength dispersive X-ray fluorescence spectrometry journal October 2019

Similar Records

Synthesis and sintering of UN-UO2 fuel composites
Journal Article · Tue Jun 16 20:00:00 EDT 2015 · Journal of Nuclear Materials · OSTI ID:1294431

Synthesis of ThN using a Carbothermic Reduction to Nitridation Process
Journal Article · Wed Jun 15 00:00:00 EDT 2016 · Transactions of the American Nuclear Society · OSTI ID:22992095

THE UC-UN AND ThC-ThN SYSTEMS
Journal Article · Sat Jun 01 00:00:00 EDT 1963 · J. Less-Common Metals · OSTI ID:4701963