A Neutron Monitor for Simultaneous Measurement of Fluence and Dose Equivalent

Technical Report · Sun Aug 01 04:00:00 EDT 1965

DOI:https://doi.org/10.2172/4616320· OSTI ID:4616320

Dvorak, Robert F. ^[1]; Dyer, Norman C. ^[1]

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1. Argonne National Lab. (ANL), Argonne, IL (United States)

A neutron detector which has application as both an area monitoring instrument and a criticality dosimeter is under development at Argonne National Laboratory. The detector simultaneously measures both dose equivalent and fluence from an exposure to fast neutrons. The moderator consists of a 12-in. -diameter, aluminum-encased paraffin sphere. The neutron sensors are nine thermal activation foils located within the moderator. The neutron fluence is determined by activation of six foils symmetrically located one inch below the surface of the moderator. For this foil array, the summed activity is nondirectional and proportional to the fluence within 10 percent over the investigated energy range from 20 keV to 2.3 MeV. The neutron dose equivalent is determined from activation of three symmetrically interlocked foils at the center of the moderator, and the summed activity is proportional to the dose equivalent within 75 percent over the same energy range. A response correction technique is described which, for monoenergetic neutrons, brings the dose equivalent to within about 10 percent. The average sensitivity of the monitor over the stated energy range, using indium foils, is 76 cpm per mrem/hr and 25 cpm per n/cm²-sec at the end of one half-life exposure at uniform radiation level.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); US Atomic Energy Commission (AEC)
• DOE Contract Number: W-31109-ENG-38
• NSA Number: NSA-20-002123
• OSTI ID: 4616320
• Report Number(s): ANL-7085
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ACTIVATION
ALUMINUM
CONFIGURATION
CRITICALITY
DOSEMETERS
ENERGY RANGE
FAST NEUTRONS
FOILS
INDIUM
Indium
MEASURED VALUES
MODERATORS
MONITORING
NEUTRON DETECTION
Neutron Energy
Neutron Source
Nuclear Criticality Safety Program (NCSP)
PARAFFIN
RADIATION DOSES
SENSITIVITY
SPHERES
SURFACES
Sensitivity
Thermal Activation