Analysis of the NorthStar Inconel 718 Window

Technical Report · Sun Sep 01 04:00:00 EDT 2019

DOI:https://doi.org/10.2172/1576467· OSTI ID:1576467

Strons, P. S. ^[1]; Bailey, J. L. ^[1]; Song, J. ^[1]; Chemerisov, S. D. ^[1]

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1. Argonne National Lab. (ANL), Argonne, IL (United States)

NorthStar Medical Radioisotopes, LLC, is planning to produce the important medical radioisotope molybdenum-99 (Mo-99) through photonuclear reactions in molybdenum-100 (Mo-100). In this approach, a target comprising multiple thin disks of enriched molybdenum metal will be bombarded with a 40-MeV electron beam. Because enriched Mo-100 is expensive, there is a desire to utilize as much beam power as possible to achieve maximum production yield and minimize the size of the target. This requirement leads to very high beam power density (heat deposition in the target), which sets challenging requirements for cooling of the target. In the latest concept developed by NorthStar, a stack of target (sintered molybdenum) disks is irradiated from two sides by a 40-MeV electron beam, with a total power of 240 kW (120 kW from each side). As shown in Figure 1, the target disks are cooled by pressurized helium gas flowing through channels between the disks. A housing encloses the target disks and helium coolant. Thinned regions on opposite sides of the housing act as windows, forming the pressure boundary between the helium within the housing and the evacuated beam tube. A pulsed (50-Hz) 40-MeV electron beam is used, with 120 kW total power and a 10% duty cycle. The pulsing beam creates a corresponding cyclic thermal load within the window material. To examine the effects of the cyclic thermal load on the window, a combination of analyses was performed, including computational fluid dynamics (CFD) and finite element analysis (FEA). The analyses presented in this report were primarily performed using the finite element method. However, because of the curved surface of the window, CFD analysis was used to calculate the convective cooling boundary included in the FEA model. Transient thermal and structural models were used to explore the window geometry, including thickness, radius of curvature, and diameter, while staying within the temperature and stress limits of the material as well as maintaining mechanical stability (i.e., avoiding buckling). Additionally, variations in the size and location of the electron beam were evaluated. Multiple parameters for the window and the electron beam were examined throughout the analysis. Upper and lower bounds were established for the window geometry parameters, and limitations were established for the size and position of the electron beam.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1576467
• Report Number(s): ANL-19/50; 157352
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE