High-power target development for accelerator-based neutron capture therapy

The production of clinically sufficient dose rates in Accelerator-based Neutron Capture Therapies (ABNCT) requires targets that can withstand ion beams of 2-10 kW or higher. Designing such a target requires knowledge of the current density profile which can exceed 1 mA/cm². A method has been developed to quantify the two-dimensional current intensity by utilizing the positrons emitted from the products of either the ¹²C(d,n) or ¹¹B(p,n) reaction. A desktop scanner was used to convert the dose profile measured with MD-55-2 radiochromic film into a map of beam current intensity. Analytic calculations coupled with Monte Carlo methods determined the resolution of this technique to be 0.22±0.01 mm. Liquid gallium metal was investigated as a possible coolant. Qualitative and quantitative comparisons between single submerged impinging jets of liquid gallium and water at low flowrates were supplemented with computational fluid dynamics. Experiments using an array of submerged jets were conducted to determine area-averaged Nusselt number correlations for water and gallium over a Reynolds number range of 7000<Re<38000. The spreading factor, β[sub]max, was introduced into the gallium correlation to account for surface wetting effects. Area-averaged heat transfer coefficients, h, produced by an array of gallium jets were found to exceed those of water for Re>13500. At a Reynolds number of 35000 an h of 10⁵ W/m²K was measured with the gallium array compared to 5.5xlO⁴W/m²K for water. Simulations of the thermal and mechanical stresses found that a gallium-cooled beryllium target could withstand beam powers of up to 20.2 kW.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Blackburn, Brandon William

Advisor dc:contributor.advisor

• Jacquelyn C. Yanch.

• Nuclear Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/30009

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/30009