skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The Behavior of ThO{sub 2}-Based Fuel Rods During Normal Operation and Transient Events in LWRs

Abstract

The thermal, mechanical, and chemical behavior of both thorium and uranium dioxide (ThO{sub 2}-UO{sub 2}) and thorium and plutonium dioxide (ThO{sub 2}-PuO{sub 2})-based fuels during in-service and hypothetical accident conditions in light water reactors (LWRs) is described. These fuels offer the possibility for increased proliferation resistance and a reduction in the stockpile of weapons-grade and reactor-grade PuO{sub 2} as well as being a more stable waste form. The behavior is described for three different designs of ThO{sub 2}-based fuels: a homogeneous mixture of ThO{sub 2}-UO{sub 2}, a microheterogeneous arrangement of the ThO{sub 2} and UO{sub 2}, and a homogeneous mixture of ThO{sub 2}-PuO{sub 2}. The behavior was calculated with widely known LWR analysis tools extended for ThO{sub 2}-based fuels: (a) MATPRO for calculating material properties, (b) FRAPCON-3 for calculating in-service fuel temperature and fission-gas release, (c) VIPRE-01 for calculating the possibility for departure from nucleate boiling, (d) HEATING7 for calculating in-service two-dimensional temperature distributions in microheterogeneous fuel, (e) SCDAP/RELAP5-3D for calculating the transient reactor system behavior and fuel behavior during loss-of-coolant accidents, and (f) FRAP-T6 for calculating the vulnerability of the cladding to cracking due to swelling of the fuel during hypothetical reactivity-initiated accidents.The analytical tools accounted for the followingmore » differences in ThO{sub 2}-based fuels relative to 100% UO{sub 2} fuel: (a) higher thermal conductivity, lower density and volumetric heat capacity, less thermal expansion, and higher melting point; (b) higher fission-gas production for {sup 233}U fission than {sup 235}U fission, but a lower gas diffusion coefficient in the ThO{sub 2} than in the UO{sub 2}; (c) less plutonium accumulation at the rim of the fuel pellets; (d) greater decay heat; (e) microheterogeneous arrangement of fuel; and (f) more-negative moderator temperature and Doppler coefficients and a smaller delayed-neutron fraction. The newly developed models for ThO{sub 2} were checked against data from the light water breeder reactor program. Calculations by these analytical tools indicate that the in-service and transient performance of homogeneous ThO{sub 2}-UO{sub 2}-based fuels with respect to safety is generally equal to or better than that of 100% UO{sub 2} fuel. The in-service and transient temperatures in the most promising neutronic design of microheterogeneous ThO{sub 2}-UO{sub 2}-based fuel are greater than the temperatures in 100% UO{sub 2} fuel but are still within normal LWR safety limits. The reactor kinetics parameters for ThO{sub 2}-PuO{sub 2}-based fuel cause a higher transient reactor power for some postulated accidents, but in general, the margin of safety for ThO{sub 2}-PuO{sub 2} fuels is equal to or greater than that in 100% UO{sub 2} fuels.« less

Authors:
 [1];  [2];  [1];  [2];  [2];  [2];  [1]
  1. Massachusetts Institute of Technology (United States)
  2. Idaho National Engineering and Environmental Laboratory (United States)
Publication Date:
OSTI Identifier:
20840210
Resource Type:
Journal Article
Journal Name:
Nuclear Technology
Additional Journal Information:
Journal Volume: 147; Journal Issue: 1; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0029-5450
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; FISSION PRODUCTS; FUEL RODS; HOMOGENEOUS MIXTURES; HYPOTHETICAL ACCIDENTS; MELTING POINTS; MIXED OXIDE FUELS; NUCLEATE BOILING; PLUTONIUM; PLUTONIUM DIOXIDE; REACTOR SAFETY; THORIUM; THORIUM OXIDES; TRANSIENTS; URANIUM 233; URANIUM 235; URANIUM DIOXIDE; WASTE FORMS; WATER COOLED REACTORS; WATER MODERATED REACTORS

Citation Formats

Long, Yun, Siefken, Larry J, Hejzlar, Pavel, Loewen, Eric P, Hohorst, Judith K, MacDonald, Philip E, and Kazimi, Mujid S. The Behavior of ThO{sub 2}-Based Fuel Rods During Normal Operation and Transient Events in LWRs. United States: N. p., 2004. Web.
Long, Yun, Siefken, Larry J, Hejzlar, Pavel, Loewen, Eric P, Hohorst, Judith K, MacDonald, Philip E, & Kazimi, Mujid S. The Behavior of ThO{sub 2}-Based Fuel Rods During Normal Operation and Transient Events in LWRs. United States.
Long, Yun, Siefken, Larry J, Hejzlar, Pavel, Loewen, Eric P, Hohorst, Judith K, MacDonald, Philip E, and Kazimi, Mujid S. Thu . "The Behavior of ThO{sub 2}-Based Fuel Rods During Normal Operation and Transient Events in LWRs". United States.
@article{osti_20840210,
title = {The Behavior of ThO{sub 2}-Based Fuel Rods During Normal Operation and Transient Events in LWRs},
author = {Long, Yun and Siefken, Larry J and Hejzlar, Pavel and Loewen, Eric P and Hohorst, Judith K and MacDonald, Philip E and Kazimi, Mujid S},
abstractNote = {The thermal, mechanical, and chemical behavior of both thorium and uranium dioxide (ThO{sub 2}-UO{sub 2}) and thorium and plutonium dioxide (ThO{sub 2}-PuO{sub 2})-based fuels during in-service and hypothetical accident conditions in light water reactors (LWRs) is described. These fuels offer the possibility for increased proliferation resistance and a reduction in the stockpile of weapons-grade and reactor-grade PuO{sub 2} as well as being a more stable waste form. The behavior is described for three different designs of ThO{sub 2}-based fuels: a homogeneous mixture of ThO{sub 2}-UO{sub 2}, a microheterogeneous arrangement of the ThO{sub 2} and UO{sub 2}, and a homogeneous mixture of ThO{sub 2}-PuO{sub 2}. The behavior was calculated with widely known LWR analysis tools extended for ThO{sub 2}-based fuels: (a) MATPRO for calculating material properties, (b) FRAPCON-3 for calculating in-service fuel temperature and fission-gas release, (c) VIPRE-01 for calculating the possibility for departure from nucleate boiling, (d) HEATING7 for calculating in-service two-dimensional temperature distributions in microheterogeneous fuel, (e) SCDAP/RELAP5-3D for calculating the transient reactor system behavior and fuel behavior during loss-of-coolant accidents, and (f) FRAP-T6 for calculating the vulnerability of the cladding to cracking due to swelling of the fuel during hypothetical reactivity-initiated accidents.The analytical tools accounted for the following differences in ThO{sub 2}-based fuels relative to 100% UO{sub 2} fuel: (a) higher thermal conductivity, lower density and volumetric heat capacity, less thermal expansion, and higher melting point; (b) higher fission-gas production for {sup 233}U fission than {sup 235}U fission, but a lower gas diffusion coefficient in the ThO{sub 2} than in the UO{sub 2}; (c) less plutonium accumulation at the rim of the fuel pellets; (d) greater decay heat; (e) microheterogeneous arrangement of fuel; and (f) more-negative moderator temperature and Doppler coefficients and a smaller delayed-neutron fraction. The newly developed models for ThO{sub 2} were checked against data from the light water breeder reactor program. Calculations by these analytical tools indicate that the in-service and transient performance of homogeneous ThO{sub 2}-UO{sub 2}-based fuels with respect to safety is generally equal to or better than that of 100% UO{sub 2} fuel. The in-service and transient temperatures in the most promising neutronic design of microheterogeneous ThO{sub 2}-UO{sub 2}-based fuel are greater than the temperatures in 100% UO{sub 2} fuel but are still within normal LWR safety limits. The reactor kinetics parameters for ThO{sub 2}-PuO{sub 2}-based fuel cause a higher transient reactor power for some postulated accidents, but in general, the margin of safety for ThO{sub 2}-PuO{sub 2} fuels is equal to or greater than that in 100% UO{sub 2} fuels.},
doi = {},
journal = {Nuclear Technology},
issn = {0029-5450},
number = 1,
volume = 147,
place = {United States},
year = {2004},
month = {7}
}