The Fission Converter-Based Epithermal Neutron Irradiation Facility at the Massachusetts Institute of Technology Reactor
- Massachusetts Institute of Technology (United States)
- Beth-Israel Deaconess Medical Center (Israel)
A new type of epithermal neutron irradiation facility for use in neutron capture therapy has been designed, constructed, and put into operation at the Massachusetts Institute of Technology Research Reactor (MITR). A fission converter, using plate-type fuel and driven by the MITR, is used as the source of neutrons. After partial moderation and filtration of the fission neutrons, a high-intensity forward directed beam is available with epithermal neutron flux [approximately equal to]10{sup 10} n/cm{sup 2}.s, 1 eV {<=} E {<=} 10 keV, at the entrance to the medical irradiation room, and epithermal neutron flux = 3 to 5 x 10{sup 9} n/cm{sup 2}.s at the end of the patient collimator. This is currently the highest-intensity epithermal neutron beam. Furthermore, the system is designed and licensed to operate at three times higher power and flux should this be desired. Beam contamination from unwanted fast neutrons and gamma rays in the aluminum, polytetrafluoroethylene, cadmium and lead-filtered beam is negligible with a specific fast neutron and gamma dose, D{sub {gamma}}{sub ,fn}/{phi}{sub epi} [less than or approximately equal] 2 x 10{sup -13} Gy cm{sup 2}/n{sub epi}. With a currently approved neutron capture compound, boronophenylalanine, the therapeutically advantageous depth of penetration is >9 cm for a unilateral beam placement. Single fraction irradiations to tolerance can be completed in 5 to 10 min. An irradiation control system based on beam monitors and redundant, high-reliability programmable logic controllers is used to control the three beam shutters and to ensure that the prescribed neutron fluence is accurately delivered to the patient. A patient collimator with variable beam sizes facilitates patient irradiations in any desired orientation. A shielded medical room with a large window provides direct viewing of the patient, as well as remote viewing by television. Rapid access through a shielded and automatically operated door is provided. The D{sub 2}O cooling system for the fuel has been conservatively designed with excess capacity and is fully instrumented to ensure detection and control of off-normal conditions. A wide range of possible abnormal events or accident scenarios has been analyzed to show that even in the worst cases, there should be no fission product release through fuel damage. This facility has been licensed to operate by the U.S. Nuclear Regulatory Commission, and initial operation commenced in June 2000.
- OSTI ID:
- 20804769
- Journal Information:
- Nuclear Science and Engineering, Vol. 140, Issue 3; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); ISSN 0029-5639
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM
BEAM MONITORS
CADMIUM
CAPTURE
CONTROL SYSTEMS
COOLING SYSTEMS
EPITHERMAL NEUTRONS
FAST NEUTRONS
FISSION
FISSION NEUTRONS
GAMMA RADIATION
HEAVY WATER
IRRADIATION
KEV RANGE
MITR REACTOR
NEUTRON CAPTURE THERAPY
NEUTRON FLUENCE
NEUTRON REACTIONS
PATIENTS
POLYTETRAFLUOROETHYLENE