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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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Latest News
First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
Yasushi Nomura, Yoshitaka Naito
Nuclear Technology | Volume 121 | Number 1 | January 1998 | Pages 3-13
Technical Paper | Kiyose Birthday Anniversary | doi.org/10.13182/NT98-A2814
Articles are hosted by Taylor and Francis Online.
Scenario identification, preparation of reliability data, and fault-tree construction were conducted for a criticality in a pulsed column of a typical model of a reprocessing facility to find a weak link in the system. The plant system data, the basic reliability data with the fault-tree analysis code FTL, were supplied from NUKEM GmbH, Germany. In this exercise, a low nitric acid concentration in the scrub flow to the pulsed column is initiated by failures of the reagent preparation system of the primary separation cycle, triggering plutonium accumulation, eventually exceeding the safety limit of the scrub column, and thus a criticality accident occurs. The occurrence frequency was evaluated to be 2.2 × 10-5/yr for this most conservative case of the accident scenario. The main contributor was investigated by the fault-tree branch analysis and identified to be human error relating to the sampling measurement for fresh nitric acid scrub feed. Because 2.2 × 10-5/yr is quite a high value in comparison with the generally accepted 10-6/yr, Monte Carlo uncertainty analysis assuming an error factor of 5 for each of the reliability data was conducted to predict a 90% confidence range of 1.9 × 10-6/yr to 8.25 × 10-5/yr. In addition, there might be unforeseen equipment failures related to the same criticality scenario. The additional analysis and discussion lead to the recommendation to adopt shape and dimension control in the design stage for the whole range of plutonium concentrations from a criticality safety point of view.
