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Solvent performance in THTR nuclear fuel reprocessing. I. Calculation of doses received by TBP-n-paraffin extractant in reprocessing THTR fuels applying a Thorex flowsheet

Journal Article · · Nucl. Technol.; (United States)
OSTI ID:7089535

The radiolytic load of the 30 vol % tributylphosphate-n-paraffin extractant to be used in the Juelich Pilot Plant for Thorium Element Reprocessing facility for reprocessing thorium high-temperature reactor (THTR) fuel elements with high burnup values (85,000 MWd/MT of heavy-metal atoms) was calculated. At a radioactivity level of approx. 2000 Ci/l, the effective beta-particle power density of the feed solution ranges up to 15 W . l/sup -1/. Most of the energy absorbed by the extractant is due to beta radiation (99%). About 1% originates from gamma radiation; contributions from alpha-particle emitters are negligible. The calculations consider the geometric parameters of the applied mixer-settler and the operational parameters of the flowsheet. The highest exposure expected will be approx. 0.2 Wh . l/sup -1/ when reprocessing fuel with 85,000 MWd/MT burnup after a cooling time of 100 days. For an easier comparison of the calculated value with other reported values, a coefficient is introduced describing the specific exposure of the extractant in terms of energy absorption per hour of passing through the contactor at a power density of l W . l/sup -1/ in the feed solution. This coefficient is independent of such individual flowsheet conditions as heavy-metal concentration or power density in the feed solution. Comparison of calculated data with other reported data for THOREX and PUREX reprocessing runs exhibits only about a four-fold specific load of the extractant in case of reprocessing high-burned-up THTR fuel with respect to low-enriched low-burned-up light water reactor fuel. This underproportional increase is due to the specific fission-product spectrum of the investigated THTR fuel arising in the course of its reactor residence time.

Research Organization:
Kernforschungsanlage, Juelich, Ger.
OSTI ID:
7089535
Journal Information:
Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 34:3; ISSN NUTYB
Country of Publication:
United States
Language:
English