ISO-CART-85 is a new mobile system for radioactive waste assay by high-resolution gamma spectroscopy. Through the use of a single very-large-area high purity germanium (HPGe) detector, and a modular collimation system, ISO-CART-85 achieves, in many cases, free release levels in reasonable count times, for in-field measurements.
The HPGe detector is provided in the form of the ORTEC IDM-200-V
, a revolutionary all-in-one integrated Gamma Spectrometer, which requires no liquid nitrogen to cool to operational temperature. Instead, a miniature Stirling cycle cryo-cooler is employed. An internal battery powers the cooler and the highly stable digital signal processing electronics for up to 3 hours or longer with battery life extending options or battery hot swap.
The new ISO-CART-II
which is the measurement system transport represents the latest generation of ISO-CART from ORTEC, enhanced through operational experience, and with some new options, such as the useful bottle-counting shield option which allows the system to be used as an “in-field counting room” to count bulk assay samples on the face of the HPGe detector. The tried-and-tested ISOPLUS software
, in its latest version now offers 64-bit compatibility with the latest Windows operating systems.
ISO-CART-85 systems are provided “ready to go”, traceably calibrated at our factory. The standard configuration comprises:
- IDM-200-V large area, fully integrated HPGe spectrometer.
- ISO-2-IDM-SHD Modular Collimator Kit. Includes three field of view collimators (2”, 4”, and 6”) and three 2” FOV collimator shields.
- Mounting hardware
- ISOPLUS waste assay software.
- Laptop computer with software installed.
- Factory calibration.
- All necessary cables and connectors.
Optionally for those who wish to supply their own laptop, a “user install and calibrate” version is available. If calibration is required but not a laptop, the calibration files can be provided for installation on the user’s own computer. The ISOPLUS software allows calibration or recalibration of the system by use of a traceable point source at any time. IT IS NOT NECESSARY TO RETURN TO OUR FACTORY TO RECALIBRATE.
ISO-CART-85 Modular Collimator: A Minimum Weight Approach to Collimation
System weight is a major consideration in mobile assay systems which require, by definition, to be moved. The ISOPLUS software operates based on the assumption that the detector “observes” a representative portion of the object through a defined “field of view” and then computes the total materials assay based on that. This requires that the detector be provided with a collimator to restrict and define a suitable field of view, representative of the sample. Another consideration is that the detector itself might be subject to external radiation from sources other than the object being measured, for example from other nearby waste samples. This might necessitate the use of a thicker collimator than otherwise needed. For this reason, and to allow choices to be made consistent with the minimization of weight, a modular collimator system has been designed in which a thinner, low-Z material-lined, field-of-view collimator can be augmented with additional detector shielding and thicker collimation as required by the background radiation.
The ISO-2-IDM-SHD Kit comprises 3 each thin-walled steel 15 mm thick, Sn/Cu lined field of view collimators, 2”, 4” and 6” in length to provide variability in field of view, and 3 each 2" deep, 1” wall thickness, lead sectional shields for the FOV collimator, (ISO-2-IDM-SHD-2). By choosing the appropriate Field of View collimator, the additional shielding may be added as circumstances require, thereby minimizing weight.
ISO-CART-85 Bottle Counting Shield Extension Option: The “In-Field Counting Lab”, Return to Base Not Required
From time to time it can be necessary in mobile assay applications to take a small bulk sample of contaminated material, for example soil, and to assay it in the “usual” measurement geometry: i.e. inside a lead shield, perhaps for screening purposes to establish that material is NOT contaminated to a lower detection limit than might be achievable with only a collimated detector. The ISO-CART-85 bottle counting shield extension may be mounted on the upward facing 6” version modular collimator and 3 each 2” lead shields to provide a small counting shield which will allow a 1 liter bottle of material to be counted directly on the endcap of the detector, in a high efficiency counting geometry.
The ISO-2-IDM-SHD-EXT option comprises the bottle counting shield extension for ISO-2-IDM-SHD and includes 6 each 1-liter bottles. The pre-calibrated ISO-CART-85 system is ready for use with this option.