Emergency unmanned airborne spectrometric (HPGe) monitoring system.

After a nuclear or radiation event, emergency responders and radiation protection authorities need quick and credible information based on reliable accident and post-accident radiological data. However, risks to people in the vicinity of the source pose serious measurement challenges. Many problems could be solved by unmanned airborne monitoring systems, but the current ones are mostly based on non-spectrometric detectors carried by drones with low bearing, short flying range and flight time. Therefore spectrometric monitoring system based on High-Purity Germanium (HPGe) detector carried by powerful unmanned helicopter has been developed. The presented unmanned aerial spectrometric system is reliable and heavy-duty and enables quick and safe identification of released radionuclides, thus provides a basis for determining the plant damage state and for planning of emergency and contamination zones. The system will support timely, effective actions that protect the public and environment against the effects of ionizing radiation. The paper describes development and performance tests of this novel system.

Metrology for decommissioning nuclear facilities: Partial outcomes of joint research project within the European Metrology Research Program.

Decommissioning of nuclear facilities incurs high costs regarding the accurate characterisation and correct disposal of the decommissioned materials. Therefore, there is a need for the implementation of new and traceable measurement technologies to select the appropriate release or disposal route of radioactive wastes. This paper addresses some of the innovative outcomes of the project "Metrology for Decommissioning Nuclear Facilities" related to mapping of contamination inside nuclear facilities, waste clearance measurement, Raman distributed temperature sensing for long term repository integrity monitoring and validation of radiochemical procedures.

Monte Carlo optimization of shielding for novel industrial free release measurement facility.

Monte Carlo (MC) simulations were done for the optimization of shielding configuration of a novel industrial radionuclide-specific pre-selection free release measurement facility. The shielding is made from unique bricks of concrete with very low specific activity of natural radionuclides. The final configuration was selected as a compromise between shielding volume and the simulated 1461keV full-energy peak detector count rates of natural 40K.

Distribution of radionuclides in an iron calibration standard for a free release measurement facility.

A Europallet-sized calibration standard composed of 12 grey cast iron tubes contaminated with (60)Co and (110m)Ag with a mass of 246kg was developed. As the tubes were produced through centrifugal casting it was of particular concern to study the distribution of radionuclides in the radial direction of the tubes. This was done by removing 72 small samples (swarf) of ~0.3g each on both the inside and outside of the tubes. All of the samples were measured in the underground laboratory HADES.

Optimization of a measurement facility for radioactive waste free release by Monte Carlo simulation.

A novel free release measurement facility (FRMF) was developed within the joint research project "Metrology for Radioactive Waste Management" of the European Metrology Research Programme. Before and during FRMF design and construction, Monte Carlo calculations with MCNPX and PENELOPE codes were used to optimize the thickness of the shielding, the dimensions of the container, and the shape of detector collimators. Validation of the numerical models of the FRMF detectors and the results of the optimization are discussed in the paper.

Calibration of stack monitors for measurement of noble gases in nuclear facilities.

In nuclear facilities stack monitors are used for the measurement of the volumetric activity of noble gases. Spectrometric measurement is needed because the content of stack effluents is always a mixture of radionuclides. In some nuclear power plants new types of monitors were installed based on HPGe detectors. For efficiency calibration a standard with the radionuclide Xe-127 was developed and calibration curve constructed in the energy range 81 keV-1293 keV. Experiental efficiencies were checked using an MC model.

Determination of corrections to true summations of photons for measurements in Marinelli beakers.

This paper describes a method of determination of correction factors for the true summation effect of photons for measurement of activity of radionuclides emitting gamma radiation. The method was tested with Marinelli beakers samples measured with coaxial germanium detectors. The advantage of this method is its simplicity since it is not necessary to determine the curves of total efficiency for each detector. The correction factor for the particular peak is determined by means of a detector index which is calculated from one of the measurements with a calibration standard.