Radiation monitoring after experimental dirty bomb explosion.

Experiments simulating radioactive dirty bomb explosions in an urban area were performed at the National Institute of NBC Protection (SUJCHBO v.v.i.), Czech Republic. A solution containing 99mTc radionuclide was dispersed by an explosion on an open-air model of a square covered with filters. Subsequently, spectra of gamma rays originating in contaminated filters were measured by a hand-held NaI(Tl) spectrometer and laboratory HPGe spectrometers. The ambient dose equivalent rate at measuring vessels was set as well. Self-made standards had been prepared by dripping a defined amount of 99mTc solution uniformly on the filters to set the 99mTc surface contamination of measured samples. The urban area model's radioactive contamination map was set using previously determined filters' locations. The defined amount of 99mTc solution was dripped non-homogenously on some filters to estimate the impact of non-homogenous filters' coverage by radioactive aerosol' particles.

Measuring and Monte Carlo Modelling of X-Ray and Gamma-Ray Attenuation in Personal Radiation Shielding Protective Clothing.

A collection of personal protective equipment (PPE), suitable for use in case of accident in nuclear facilities or radiological emergencies, was gathered at the National Institute for Nuclear, Chemical and Biological Protection, Czech Republic. The shielding characteristics of the various PPE materials were measured via narrow geometry spectral attenuation measurements with point radionuclide sources covering a broad range of photon energies. Photon relative penetration and attenuation for relevant energies of the spectra were the principal experimentally determined quantities for tested PPE. Monte Carlo simulations in the MCNPX™ code were carried out to determine photon attenuation for respective energies in the tested PPE, and the results were compared to those determined experimentally. Energy depositions in a unit volume of an ORNL phantom were simulated in a radioactive aerosols atmospheric environment to determine effective doses both for the whole body and in various organs in the human torso during exposure to different dispersed radioactive aerosols while wearing one of the PPE protecting against X- and gamma-ray. This work aimed to determine the effective dose and its decrease for individual PPE protecting against X- and gamma-ray.

Attenuation of X and Gamma Rays in Personal Radiation Shielding Protective Clothing.

A collection of personal radiation shielding protective clothing, suitable for use in case of accidents in nuclear facilities or radiological emergency situations involving radioactive agents, was gathered and tested at the Nuclear Protection Department of the National Institute for Nuclear, Chemical and Biological Protection, Czech Republic. Attenuating qualities of shielding layers in individual protective clothing were tested via spectra measurement of x and gamma rays, penetrating them. The rays originated from different radionuclide point sources, the gamma ray energies of which cover a broad energy range. The spectra were measured by handheld spectrometers, both scintillation and High Purity Germanium. Different narrow beam geometries were adjusted using a special testing bench and a set of various collimators. The main experimentally determined quantity for individual samples of personal radiation shielding protective clothing was x and gamma rays attenuation for significant energies of the spectra. The attenuation was assessed comparing net peak areas (after background subtraction) in spectra, where a tested sample was placed between the source and the detector, and corresponding net peak areas in spectra, measured without the sample. Mass attenuation coefficients, which describe attenuating qualities of shielding layers materials in individual samples, together with corresponding lead equivalents, were determined as well. Experimentally assessed mass attenuation coefficients of the samples were compared to the referred ones for individual heavy metals.