This invention consists of a cadmium zinc telluride (CZT) gamma spectroscopy system that is highly portable and can be operated by one person. It consists of a multichannel analyzer developed for expected default frequency (EDF).The system along with the novel methods of this technology, allows the device to be used to quantify the level and type of radioactive corrosion found in light water reactors or other contaminated systems. This can be accomplished without disassembly of the structures being tested.
Advantages Over Other Technologies
Accurate - The semiconductor-like detector is capable of providing the data that facilitate trending nuclide specific gamma activity concentration. CZT measurements are within +/- 10% of values measured with Germanium-based detectors.
Portable - Because of the portability of the system, it requires only one operator to complete the measurements.
Reduced Man-Rem - Germanium based systems require scaffolding, coolant and several individuals to complete the measurements. A CZT based system can complete the measurements in one day, less than a third of the time for a germanium-based system.
Better Resolution compared with NAI - Moreover, the CZT detector has a superior full width at half maximum characteristics the Sodium Iodide (NaI) detector. This feature allows for better resolution of the radioscopes in the key areas of energy interest (between 511 keV and 1.33 MeV).
Cost Effective - The equipment is far more portable than a liquid cooled detector because a cooling dewar is not required and the collimation is smaller and lighter in weight than those commonly used with portable ISOCs units. This feature saves time because it eliminates the need to plan, build scaffolding for support, transport liquid nitrogen cooling and rigging the heavier ISOCs systems into position.
Comparable Energy Range - CZT has an energy range of between 100keV and 1.8 MeV and a sensitivity of between 10 and 1000 mrem/hr (0.1 to 10 mSv/hr using 500 mm3 sensors. This is comparable to the ISOCs systems currently used by the industry.
Time Efficient - Data point acquisition time for most measurements is 20 minutes. This is one third the time typically required for an ISOCs system.
Proven - This system has been used at Surry Units 1 & 2, North Anna Units 1&2, Turkey Point, Fermi 2, Braver Valley, Braidwood, Byron, Kewaunee, Nine Mile Point, V.C. Summer and DC Cook. The data is available with permission from the sites
Technology Status
A prototype has been produced and is working. This matter issued as USP 9,551,676, on January 24, 2014.