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Title: Optimization of the dissolution of molybdenum disks. FY-16 results

Argonne National Laboratory, with support from the National Nuclear Security Administration’s Material Management and Minimization program, is providing technical development assistance to NorthStar Medical Technologies LLC in its pursuit of two pathways for production of molybdenum-99. As a short-term answer to demands, NorthStar plans to use the 98Mo(n,γ) 99Mo reaction (neutron capture) pathway at the University of Missouri Research Reactor. As a long-term solution, NorthStar will produce 99Mo via the photonuclear reaction, 100Mo(γ,n)99Mo, from irradiation of enriched Mo targets by an electron accelerator. Processing of irradiated targets, from either production mode, requires dissolution of the target material in H2O2 followed by a concentration step, addition of ferric ion to precipitate impurities, and conversion of the final solution to 5M potassium hydroxide solution of potassium molybdate. Currently, NorthStar is using pressed and sintered Mo disks as targets. Several options are being considered for the design of Mo targets for the production of 99Mo using the (γ,n) reaction. In the current design, the target holder contains a series of sintered Mo disks lined up perpendicular to two incident electron beams, one entering from each side of the target stack. In this configuration, the front-most disks absorb most of the heat from themore » electron beam and need to be thinner to allow for better cooling, while the middle of the target can be thicker. Distribution of the total mass of Mo allows for larger masses of Mo material and thus larger production batches of 99Mo. A limitation of the sintering approach is the production of very thin disks. On the other hand, recent advances in 3D printing allow for laser-melting on metals with high melting points, such as Mo. This approach gives more flexibility in the target design, and much thinner target components can be achieved than when the traditional press-and-sinter approach is used. Another advantage is that an entire target, including the housing, can be fabricated from Mo. Recent progress on dissolution of sintered Mo disks is well documented [1-4]. We have demonstrated that several factors can play important roles in dissolution behavior: particle size of Mo metal used for production of targets, sintering conditions, degree of open porosity, and thickness of the sintered Mo targets. Here we report experimental results from studies of small-scale dissolution of sintered Mo disks fabricated from various recycled and commercial Mo materials, and dissolution of 3D-printed Mo disks that were fabricated by Oak Ridge National Laboratory (ORNL). We also report on large-scale dissolution studies with 600 g batches of sintered Mo disks.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
OSTI Identifier:
1331320
Report Number(s):
ANL/NE--16/28
131127
DOE Contract Number:
AC02-06CH11357
Resource Type:
Technical Report
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY