Abstract
As part of a joint activity between ANL and Kharkov Institute of Physics and Technology in Ukraine, the thermal-hydraulic analyses of various electron target designs are being performed for an accelerator-driven subcritical facility. The facility, driven by en electron accelerator, is intended for use in medical isotope production. In this work, various target configurations are being considered and tungsten as well as Al-clad uranium are evaluated as target materials. Prior to the target thermal-hydraulic analysis, the initial neutron physics studies have been completed to characterize the electron beam energy deposition, neutron generation and utilization in the subcritical pile using the MCNP code.[1] Based on the provided bounding target dimensions, beam parameters, and energy deposition curves, the commercial CFD software STAR-CD[2] is being used to complete the thermal-hydraulic design work to satisfy the specified target performance criteria and engineering design requirements. A schematic of one of the target configurations being studied is shown in the Fig. 1. The coolant (water) at room temperature flows parallel to the electron beam, splits among narrow gaps between the target disks to cool them, and returns in opposite direction to the beam on the other side of the disks. Since each disk is cooled from both sides, its thermal deformation is expected to be minimal with this configuration. The main thermal design criterion is to maintain the water temperatures about 50°C below the boiling point (about 152°C at 4 atm). So far, both the tungsten and uranium target materials are considered for three beam power cases: 100, 150, and 200 MeV. Various target disk and coolant channel thickness are evaluated and the thermal design criterion appears to be satisfied with less than 7 m/s nominal flow rate in the inlet and outlet channels. At this flow rate, approximately only a 5°C temperature difference is expected between the inlet and outlet channels. However, since the turbulence in flow field is suppressed in the 2 mm wide gaps between the target disks and dissipates quickly, the heat transfer from the heated target is limited mainly to laminar flow. Furthermore, small recirculation zones appear near the edges of the target disks (midway between the inlet and outlet channels), and it results in hotspots that could complicate the structural design of the target assembly. The Fig. 1 shows the temperature distributions inside the tungsten disks for 150 MeV beam case, as an example. The different target configurations, and various other target disk cooling options that avoid hotspots, are currently being evaluated based on iterations between the thermo-fluids and thermo-structural analyses.
Original language | English |
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Pages (from-to) | 419 |
Number of pages | 1 |
Journal | Transactions of the American Nuclear Society |
Volume | 94 |
State | Published - 2006 |
Externally published | Yes |
Event | 2006 Annual Meeting - American Nuclear Society - Reno, NV, United States Duration: Jun 4 2006 → Jun 8 2006 |