Mo100 to Mo99 Target Cooling Enhancements Report

Woloshun, Keith Albert¹  Dale, Gregory E.¹  Olivas, Eric Richard¹  Mocko, Michal¹ 

[1] Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

关键词: TARGETS;    MOLYBDENUM 99;    MOLYBDENUM 100;    THICKNESS;    MILLI AMP BEAM CURRENTS;    COOLANTS;    THERMAL HYDRAULICS;    HELIUM;    DESIGN;    COMPARATIVE EVALUATIONS;    HEAT TRANSFER;    MEV RANGE 10-100;    BLOWERS;    COOLING;    CONFIGURATION;    MASS TRANSFER;    F;   

DOI  :  10.2172/1238140
RP-ID  :  LA--UR-16-20939
PID  :  OSTI ID: 1238140
Others  :  TRN: US1600534

学科分类：核物理和高能物理

美国|英语

来源: SciTech Connect

【 摘 要 】

Target design requirements changed significantly over the past year to a much higher beam current on larger diameter disks, and with a beam impingement on both ends of the target. Scaling from the previous design, that required significantly more mass flow rate of helium coolant, and also thinner disks. A new Aerzen GM12.4 blower was selected that can deliver up to 400 g/s at 400 psi, compared to about 100 g/s possible with the Tuthill blower previously selected.Further, to accommodate the 42 MeV, 2.7 mA beam on each side of the target, the disk thickness and the coolant gaps were halved to create the current baseline design: 0.5 mm disk thickness (at 29 mm diameter) and 0.25 mm coolant gap. Thermal-hydraulic analysis of this target, presented below for reference, gave very good results, suggesting that the target could be improved with fewer, thicker disks and with disk thickness increasing toward the target center. The total thickness of Mo100 in the target remaining the same, that reduces the number of coolant gaps. This allows for the gap width to be increased, increasing the mass flow in each gap and consequently increasing heat transfer. A preliminary geometry was selected and analyzed with variable disk thickness and wider coolant gaps. The result of analysis of this target shows that disk thickness increase near the window was too aggressive and further resizing of the disks is necessary, but it does illustrate the potential improvements that are possible. Experimental and analytical study of diffusers on the target exit has been done. This shows modest improvement in requcing pressure drop, as will be summarized below. However, the benefit is not significant, and implementation becomes problematic when disk thickness is varying. A bull nose at the entrance does offer significant benefit and is relatively easy to incorporate. A bull nose on both ends is now a feature of the baseline design, and will be a feature of any redesign or enhanced designs that follow.