L. I. Urutskoev

Determination of surface activity and radiation spectrum characteristics inside buildings by a gamma locator

Abstract A gamma locator designed to conduct contamination survey inside buildings connected with nuclear production is developed. The device consists of a detector head and a remote control unit connected with a cable (>150 m). The detector head (200 × 200 × 250 mm 3 ; the weight is nearly 40 kg) is a collimated scintillated gamma detector installed on a scanning unit. The gamma detector is placed in a lead shielding with the collimator having an entrance angle near 10°. The detector head contains a TV camera and laser distance device. The remote control unit provides operation and processing of the acquired information. The gamma detector is based on a system of CsI(Tl) scintillators and an Si photodiode. The detector energy resolution (nearly 9% for radiation of 137 Cs) provides identification of gamma radiating isotopes such as 57 Co, 137 Cs, 40 K, 60 Co, 131 I and 154 Eu. The gamma locator threshold of determination is 250 Bq/cm 2 for a 10 cm 3 scintillator and 137 Cs radiation. The system allows one to measure the effective surface activity density (for 137 Cs radiation) of all building surfaces and to reconstruct an exposed dose rate distribution within the volume of the investigated space.

Computational and experimental justification of a method for determining the137Cs contamination density and depth in soil

For decontamination and to make well-founded decisions concerning the rehabilitation of populated points subjected to radioactive contamination after the Chernobyl accident, it was necessary to develop a method that would make it possible to determine reliably the density distribution of the Cesium-137 contamination at the populated points with a spatial resolution of approximately 1-2 meters. The method must be efficient and it must provide tens of thousands of measurements for one field season. Each measurement must be inexpensive so that the inspection of the territory would be economically viable. It is extremely important to estimate also the penetration depth of Cesium-137 in the soil. In this paper, we present a computational and experimental method for this method.

Measurements of photon ionizing radiation fields in the reactor room of the 4th power-generating unit of the chernobyl nuclear power plant

A radiation examination of the reactor room of the damaged fourth unit of the Chernobyl nuclear power plant was performed. The most strongly radiating surfaces were determined. Digital maps of the distribution of the effective surface activity on the inner surfaces of the room were constructed from the measurement results. 4 figures, 1 table, 10 references.

History of development and application of gamma-ray imagers in Russia since 1986

Abstract Devices for remote mapping of radioactive contamination developed at RECOM Ltd., the daughter institution of Kurchatov Institute, since 1986 are described and typical examples of their application are shown. The following devices are discussed: Spectrum-sensitive collimated devices for mapping of radioactivity on contaminated surfaces – scanning collimated Gamma Locator and device for field 137 Cs contamination mapping – CORAD; devices for gamma-ray imaging – computer-controlled High-Energy Radiation Visualizer (HERV) and Coded Mask Imager.