Sensors neutron-based

Neutron or y Sensors Neutron- or y -based sensors are similar in concept to the X-ray sensors. They use different forms of excitation and different detectors, but the basic forms of transmission or backscatter follow the pattern described above. Both normally rely on extensive computation for signal processing called computed tomography, where the detector signals are combined to synthesize an image of the irradiated object. 

A short description of possible nuclear applications of boron-based materials had been done by Potapov (1961) in an old overview that included the nuclear power industry (e.g., control rods of nuclear reactors) solid-state electronics (e.g., counters of neutrons and neutron energy sensors) radiation chemistry (e.g., acceleration of technological processes) etc. For these purposes, "B nuclei are useless, but °B nuclei are useful due to a large cross section of interaction with thermal neutrons, °B converts them into heavy ionizing particles. Besides, °B isotope is applicable for neutron radiation protection (Stantso 1983) and also in medicine, e.g., in boron neutron capture therapy (BNCT) for treating cancer tumors (Desson 2007). 

One of the most interesting applications of the HSAB concept consists in the prediction of the stability of the complexes formed owing to interaction of alkali metal halides with rare-earth metal halides. These systems are of great interest for the materials science of scintillation materials the said complex halides are now considered among the most promising scintillation detectors and sensors. Besides, the Li- and Gd-based materials are especially convenient as effective detectors of thermal neutrons. The compositions and stability of the formed compounds depend considerably on the kind of acids and bases from which the compound is formed. So, Li+ cation is one of the hardest cation acids, and, therefore, the formation of stable complex halides of Li and lanthanides according to reaction ... 

The electric conductivity of various samples of germanium and silicon doped with °B during the neutron irradiation was measured by Kervalishvili et al. (1993). In particular, measurements of neutron fields of various nuclear plants with sensors made of these materials have been carried out. The selection of the base material and the concentration of °B impurity allowed the efficiency of neutron detection and flux measurement to be varied. Such neutron dosimeters possess memory and can be used as witnesses of unusual situations in nuclear plants. 

It was clearly demonstrated that the composite BN semiconductor polycrystalline bulk detectors with BN grains embedded in a polymer matrix operate as an effective detector of thermal neutrons even if they contain natural boron only (Uher et al. 2007). A reasonable signal-to-noise ratio was achieved with detector thickness of about 1 mm. A Monte Carlo simulation of neutron thermal reactions in the BN detector was done to estimate the detection efficiency and compare with widely used He-based detectors to prove advantages of BN detectors. They are found to be promising for neutron imaging and for large area sensors. 

Moisture sensors/methods standard gravimetric method (SGM) microwave phase shift (MPS) microwave attenuation (MA) near-infrared (NIR) capacitance and conductivity (CC) radiofrequency transmission (RFT) neutron moderation activation (NMA) low resolution (LR) direct physical measurement (DPM) based on the drag force principle. 

The Reactor Controllers control the reactor and maintain continuity of electrical power to the spacecraft based on sensor inputs. The reactor sensors include, but are not limited to, hot leg temperature, cold leg temperature, pressure, flow, neutron flux, fission products, continuous control device assembly position, and discrete valve and control device assembly positions. Details of the mass for circuit cards, sensors and cabling are contained in Reference 4-2 and are summarized below. 

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