A neutron dosemeter for nuclear criticality accidents.
A neutron dosemeter which offers instant read-out has been developed for nuclear criticality accidents. The system is based on gels containing emulsions of superheated dichlorodifluoromethane droplets, which vaporise into bubbles upon neutron irradiation. The expansion of these bubbles displaces an equivalent volume of gel into a graduated pipette, providing an immediate measure of the dose. Instant read-out is achieved using an array of transmissive optical sensors which consist of coupled LED emitters and phototransistor receivers. When the gel displaced in the pipette crosses the sensing region of the photomicrosensors, it generates a signal collected on a computer through a dedicated acquisition board. The performance of the device was tested during the 2002 International Accident Dosimetry Intercomparison in Valduc, France. The dosemeter was able to follow the initial dose gradient of a simulated accident, providing accurate values of neutron kerma; however, the emulsion was rapidly depleted of all its drops. A model of the depletion effects was developed and it indicates that an adequate dynamic range of the dose response can be achieved by using emulsions of smaller droplets.
d'Errico
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Department of Therapeutic Radiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA. francesco.derrico@yale.edu
Curzio
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Ciolini
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Del Gratta
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A
Nath
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R
D000465:Algorithms; D001822:Body Burden; D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods*; D006801:Humans; D008956:Models, Chemical; D009502:Neutrons; D009688:Nuclear Reactors; D009862:Online Systems; D011785:Quality Assurance, Health Care / Q000379:methods; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D018788:Radioactive Hazard Release; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D017751:Safety Management / Q000379:methods; D012680:Sensitivity and Specificity