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Title: Determination of /sup 232/U daughter products released from HTGR fuel during refabrication. Part 2

Abstract

During the heat treatment step of High Temperature Gas-Cooled Reactor (HTGR) fuel beads, the /sup 233/U-loaded fuel beads are exposed to temperatures as high as 1700/sup 0/C. Since /sup 233/U fuel beads unavoidably contain a small percentage of /sup 232/U, decay products of /sup 232/U might be released during the heat treatment step. To avoid shielding requirements, experiments were conducted using /sup 232/Th-loaded fuel beads rather than /sup 232/U-loaded fuel beads. Decay products of /sup 232/U and /sup 232/Th are the same after /sup 228/Th. Experimental data were obtained by monitoring the 583 and 2614 keV gamma emissions of /sup 208/Tl. Computer simulations of the decay process and experimental data were used to infer what relative amount of the daughter products was removed. The carbonization step (300 to 500/sup 0/C) has an effect on the loss of daughter products in the conversion step. Using uncarbonized fuel beads, approximately 50 percent of /sup 220/Rn was removed at 300/sup 0/C and approximately 20 percent of /sup 220/Rn was removed at 200/sup 0/C. At most, 5 percent of /sup 220/Rn was removed from uncarbonized beads at 25/sup 0/C. Marginal /sup 220/Rn loss was detected at 100/sup 0/C using pre-carbonized beads. At 1400/sup 0/C,more » 92 percent /sup 212/Pb, 70 to 90 percent /sup 212/Bi, and 0 percent /sup 224/Ra losses were observed. At 1600/sup 0/C, 100 percent /sup 212/Pb, 80 to 100 percent /sup 212/Bi, and 3 to 7 percent /sup 224/Ra losses were observed. At 1750/sup 0/C, 100 percent /sup 212/Pb, 80 to 100 percent /sup 212/Bi, and 62 percent /sup 224/Ra losses were observed. At 1800/sup 0/C, 100 percent /sup 212/Pb, 80 to 100 percent /sup 212/Bi, and 86 percent /sup 224/Ra losses were observed.« less

Authors:
; ;
Publication Date:
Research Org.:
Massachusetts Inst. of Tech., Oak Ridge, Tenn. (USA). School of Chemical Engineering Practice
OSTI Identifier:
7150115
Report Number(s):
ORNL/MIT-210
TRN: 76-021751
DOE Contract Number:
W-7405-ENG-26
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BISMUTH 212; RADIATION MONITORING; FUEL FABRICATION PLANTS; DESIGN; LEAD 212; NUCLEAR FUELS; CARBONIZATION; RADIUM 224; RADON 220; URANIUM 232; DAUGHTER PRODUCTS; HEAT TREATMENTS; HTGR TYPE REACTORS; LOSSES; ACTINIDE ISOTOPES; ACTINIDE NUCLEI; ALKALINE EARTH ISOTOPES; ALPHA DECAY RADIOISOTOPES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BISMUTH ISOTOPES; CHEMICAL REACTIONS; DAYS LIVING RADIOISOTOPES; DECOMPOSITION; ENERGY SOURCES; EVEN-EVEN NUCLEI; FUELS; GAS COOLED REACTORS; GRAPHITE MODERATED REACTORS; HEAVY NUCLEI; HOURS LIVING RADIOISOTOPES; ISOTOPES; LEAD ISOTOPES; MONITORING; NUCLEAR FACILITIES; NUCLEI; ODD-ODD NUCLEI; RADIOISOTOPES; RADIUM ISOTOPES; RADON ISOTOPES; REACTOR MATERIALS; REACTORS; SECONDS LIVING RADIOISOTOPES; URANIUM ISOTOPES; YEARS LIVING RADIOISOTOPES; 050700* - Nuclear Fuels- Fuels Production & Properties; 360201 - Ceramics, Cermets, & Refractories- Preparation & Fabrication; 400103 - Radiometric & Radiochemical Procedures- (-1987)

Citation Formats

Bencini-Tibo, L.F., Horton, J.R., and Kelley, D.F. Determination of /sup 232/U daughter products released from HTGR fuel during refabrication. Part 2. United States: N. p., 1975. Web. doi:10.2172/7150115.
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Bencini-Tibo, L.F., Horton, J.R., & Kelley, D.F. Determination of /sup 232/U daughter products released from HTGR fuel during refabrication. Part 2. United States. doi:10.2172/7150115.
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Bencini-Tibo, L.F., Horton, J.R., and Kelley, D.F. Fri . "Determination of /sup 232/U daughter products released from HTGR fuel during refabrication. Part 2". United States. doi:10.2172/7150115. https://www.osti.gov/servlets/purl/7150115.
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@article{osti_7150115,
title = {Determination of /sup 232/U daughter products released from HTGR fuel during refabrication. Part 2},
author = {Bencini-Tibo, L.F. and Horton, J.R. and Kelley, D.F.},
abstractNote = {During the heat treatment step of High Temperature Gas-Cooled Reactor (HTGR) fuel beads, the /sup 233/U-loaded fuel beads are exposed to temperatures as high as 1700/sup 0/C. Since /sup 233/U fuel beads unavoidably contain a small percentage of /sup 232/U, decay products of /sup 232/U might be released during the heat treatment step. To avoid shielding requirements, experiments were conducted using /sup 232/Th-loaded fuel beads rather than /sup 232/U-loaded fuel beads. Decay products of /sup 232/U and /sup 232/Th are the same after /sup 228/Th. Experimental data were obtained by monitoring the 583 and 2614 keV gamma emissions of /sup 208/Tl. Computer simulations of the decay process and experimental data were used to infer what relative amount of the daughter products was removed. The carbonization step (300 to 500/sup 0/C) has an effect on the loss of daughter products in the conversion step. Using uncarbonized fuel beads, approximately 50 percent of /sup 220/Rn was removed at 300/sup 0/C and approximately 20 percent of /sup 220/Rn was removed at 200/sup 0/C. At most, 5 percent of /sup 220/Rn was removed from uncarbonized beads at 25/sup 0/C. Marginal /sup 220/Rn loss was detected at 100/sup 0/C using pre-carbonized beads. At 1400/sup 0/C, 92 percent /sup 212/Pb, 70 to 90 percent /sup 212/Bi, and 0 percent /sup 224/Ra losses were observed. At 1600/sup 0/C, 100 percent /sup 212/Pb, 80 to 100 percent /sup 212/Bi, and 3 to 7 percent /sup 224/Ra losses were observed. At 1750/sup 0/C, 100 percent /sup 212/Pb, 80 to 100 percent /sup 212/Bi, and 62 percent /sup 224/Ra losses were observed. At 1800/sup 0/C, 100 percent /sup 212/Pb, 80 to 100 percent /sup 212/Bi, and 86 percent /sup 224/Ra losses were observed.},
doi = {10.2172/7150115},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Mar 21 00:00:00 EDT 1975},
month = {Fri Mar 21 00:00:00 EDT 1975}
}
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Technical Report:
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DOI:  10.2172/7150115
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  • ; ; ; ...
    During the refabrication of High Temperature Gas-Cooled Reactor (HTGR) fuel particles, uncoated resin beads loaded with /sup 233/U are exposed to temperatures as high as 1700/sup 0/C. Since /sup 233/U fuels unavoidably contain trace quantities of /sup 232/U, /sup 232/U daughter products, such as /sup 220/Rn and others, may evolve from the uncoated resin beads at high temperatures. Experiments with a /sup 232/Th-loaded resin, rather than a /sup 232/U-loaded resin, precluded shielding requirements because of the lower daughter product activity of /sup 232/Th. Below /sup 228/Th the decay chains of /sup 232/U and /sup 232/Th are identical. The losses ofmore » decay chain species were investigated by monitoring the 583 and 2615 keV gamma emissions of /sup 208/Tl. Computer-generated curves corresponding to various combinations of losses were compared to experimental data obtained at 400, 500, 600, 700, 800, 1000, and 1700/sup 0/C. From 400 to 700/sup 0/C the loss of /sup 220/Rn was 100 percent, and losses of other species were not observed. At 800/sup 0/C and above, the losses of /sup 212/Pb and /sup 212/Bi were significant. Loss of /sup 212/Pb appears complete at 1000/sup 0/C. A small percentage of /sup 224/Ra was released at 1700/sup 0/C, but no evidence of its release at lower temperatures was observed.« less

  • ;
    Eleven /sup 233/U solution critical assemblies spanning an H//sup 233/U ratio range of 40 to 2000 and a bare metal /sup 233/U assembly have been calculated with the ENDF/B-IV and Hansen-Roach cross sections. The results from these calculations are compared with the experimental results and with each other. An increasing disagreement between calculations with ENDF/B and Hansen-Roach data with decreasing H//sup 233/U ratio was observed, indicative of large differences in their intermediate energy cross sections. The Hansen-Roach cross sections appeared to give reasonably good agreement with experiments over the whole range; whereas the ENDF/B calculations yielded high values for k/submore » eff/ on assemblies of low moderation. It is concluded that serious problems exist in the ENDF/B-IV representation of the /sup 233/U cross sections in the intermediate energy range and that further evaluation of this nuclide is warranted. In addition, it is recommended that an experimental program be undertaken to obtain /sup 233/U criticality data at low H//sup 233/U ratios for verification of generalized criticality safety guidelines. Part II of this report presents the results of criticality calculations on specific pieces of equipment required for HTGR fuel refabrication. In particular, fuel particle storage hoppers and resin carbonization furnaces are criticality safe up to 22.9 cm (9.0 in.) in diameter providing water or other hydrogenous moderators are excluded. In addition, no criticality problems arise due to accumulation of particles in the off-gas scrubber reservoirs provided reasonable administrative controls are exercised.« less

  • ; ; ; ...
    Rate controlling factors in the conversion of UO/sub 2/ + C microspheres to UC/sub 2/ + C were investigated using a 13-cm-dia fluidized bed furnace. X-ray diffraction, ion microprobe, and microstructural examination revealed that the conversion of UO/sub 2/ to UC/sub 2/ began at the surface of the microsphere and progressed toward the central unreacted core. Kinetic models for solid state reactions in spheres were evaluated by using quantitative mass spectrometric data on the rae of evolution of carbon monoxide during conversion. This analysis revealed that the rate of conversion was controlled by reaction at the outer surface of themore » microsphere. Also, decreased partial pressures of carbon monoxide were found to accelerate the rate of reaction.« less