The sum-peak counting method was applied for 125I absolute activity measurement. Count rate-dependent corrections for random summing and dead time effects were experimentally determined at different count rates and in several experimental conditions. Two NaI(Tl) crystals of different volumes were used. They were connected to pulse recording systems with different characteristics, with or without pile-up rejection live-time corrector circuits (PUR/LTC). A theoretical model was proposed to explain the different behaviours found experimentally. It is shown that count rate-dependent effects are drastically reduced by the use of PUR/LTC. [All rights reserved Elsevier]

A 64Cu national primary standard, was developed by the National Institute for Ionising Radiation Metrology (INMRI) of the ENEA (ENEA-INMRI) using the CIEMAT/NIST method of 4πβ liquid scintillation spectrometry with 3H-standard efficiency tracing. Relatively short 64Cu half-life is required for the work to be performed at the production site. It was produced at the Scanditronix MC40 Cyclotron of the Joint Research Centre (JRC) of the European Commission (Ispra, Italy) through the 64Zn(d,2p) 64Cu reaction. Significant efforts were made to identify and quantify the impurities of 61Cu and 65Zn in the mother solution, which were activated through the 64Zn(d,n) 61Cu and 64Zn(d,p) 65Zn reactions, respectively. To this purpose, a new procedure for the determination of pure β-emitter impurities by the CIEMAT/NIST method has been applied. A transfer standard portable well-type ionisation chamber was also calibrated with minimum uncertainty.

A 177Lu primary standard was developed at the ENEA-INMRI in the frame of an international comparison organized by BIPM and piloted by NIST (USA). The CIEMAT/NIST method with 3H standard source as tracer was used for standardizing a solution of 177Lu. The activity value was compared also with the measurements of the same mother solution carried out by the 4pigamma integral counting method. Particular efforts were made to identify and quantify the long-lived 177mLu impurity in the mother solution. The results obtained by the two methods are in good agreement within their standard uncertainties. The arithmetic mean of the two values is in good agreement with the Comparison Reference Value (CRV). By the new primary standard two well-type ionization chambers (ICs), one fixed and the other one portable, were calibrated with an uncertainty lower than 2%. These ICs are used for routinely applications in the activity measurements of short-lived radionuclides particularly useful for medical applications. [All rights reserved Elsevier].

Two CERN Monte Carlo codes, i.e. GEANT3.21 and GEANT4, were compared. The specific routine (sch2for), implemented in GEANT3.21 to simulate a disintegration process, and the G4RadioactiveDecay class, provided by GEANT4, were used for the computation of the full-energy-peak and total efficiencies of several radionuclides. No reference to experimental data was involved. A level of agreement better than 1%for the total efficiency and a deviation lower than 3.5%for the full-energy-peak efficiencies were found.

Two CERN Monte Carlo codes, i.e. GEANT3.21 and GEANT4, were compared. The specific routine (sch2for), implemented in GEANT3.21 to simulate a disintegration process, and the G4RadioactiveDecay class, provided by GEANT4, were used for the computation of the full-energy-peak and total efficiencies of several radionuclides. No reference to experimental data was involved. A level of agreement better than 1%for the total efficiency and a deviation lower than 3.5%for the full-energy-peak efficiencies were found.

Abstract In 2014, the first three comparisons of activity measurements of 18 F were carried out at the VNIIM, NPL and the ENEA-INMRI using the BIPM’s Transfer Instrument of the International Reference System. The transfer instrument and the NMIs primary measurement methods are briefly described. The degrees of equivalence with the key comparison reference value defined in the frame of the corresponding SIR comparison have been evaluated. World-wide consistency of activity measurements of 18 F is demonstrated. Highlights • The SIRTI for activity comparisons of short-lived radionuclides was extended to 18 F. • The three first 18 F SIRTI comparisons took place at the VNIIM, NPL and the ENEA-INMRI. • Relative uncertainties of the NMIs primary measurements ranged from 0.3% to 0.6%. • Relative uncertainties of the SIRTI measurements ranged from 0.06% to 0.14%. • The comparison results agree with the SIR KCRV within 1 or 2 standard uncertainties.

Abstract This paper is concerned with the modeling of the transmission of beta rays through thin foils in planar geometry based on the plane source concept, using Monte Carlo simulation of electron transport and least squares fitting. Applications of modeling results for calculating the efficiency of large-area beta sources, transmission coefficient of beta rays through thin foils and the beta detection efficiency of large-area detectors used in surface contamination measurements are also presented. Highlights • A mathematical model of electron transport in planar geometry is developed. • The model is based on the plane source concept. • The efficiency of plane sources is computed using Monte Carlo method. • A simple function for the plane source efficiency is obtained by curve fitting. • Applications of the mathematical model are also presented.

Abstract A severe supply crisis of 99 Mo, precursor of 99m Tc a diagnostic radionuclide largely used in Nuclear Medicine, occurred in 2008–2009 due to repeated shut-down of the two main (aged) fission reactors. An alternative route for producing 99 Mo by 100 Mo(n,2n) 99 Mo reaction was investigated at ENEA. The experiment, designed according to Monte Carlo simulations performed with the Fluka code, produced 99 Mo by irradiating a natural Molybdenum powdered target with 14 MeV neutrons produced at the Frascati Neutron Generator. The 99 Mo specific activity was measured at metrological level by γ-ray spectrometry. Highlights • The problem of 99m Tc crisis in the world. • 99 Mo production at ENEA via 14 MeV neutron beam. • 99 Mo produced, identified and measured by γ-ray spectrometry. • Fluka code for the design phase and its benchmarking. • Perspectives on 99 Mo/ 99m Tc production by intense 14 MeV neutron beams.

Abstract This paper describes a new approach in evaluating the surface beta contamination using the direct method of measurement. It makes use of previous results obtained in numerical modeling of electron transport in planar geometry and is mainly based on the estimation of the efficiency of contamination sources for beta radiation and its standard uncertainty using the available information concerning the component materials of the sources and their main parameters. Experimental results illustrate the appropriateness of the new approach for surface beta contamination measurements. Highlights • A new approach in evaluating surface beta contamination is described. • The approach is based on the evaluation of the source efficiency for beta radiation. • It alleviates difficulties in uncertainty evaluation in beta contamination measurements.

Abstract Disintegration of 12 C nuclei by tagged photons of 700–1500 MeV energy at the GRAAL facility has been studied by means of the LAGRAN γ E detector with a wide angular acceptance. The energy and momentum distributions of produced neutrons and protons as well as their multiplicity distributions were measured and compared with corresponding distributions calculated with the RELDIS model based on the intranuclear cascade and Fermi break-up models. It was found that eight fragments are created on average once per about 100 disintegration events, while a complete fragmentation of 12 C into 12 nucleons is observed typically only once per 2000 events. Measured multiplicity distributions of produced fragments are well described by the model. The measured total photoabsorption cross section on 12 C in the same energy range is also reported.

The EMRP project MetroDECOM was concerned with research addressing all aspects of nuclear decommissioning in order to deliver integrity and cost-effectiveness in support of clearance and disposal processes as well as improving safety and accuracy. One of the work packages was focused on the characterisation of materials present on decommissioning. Within this work package, work on scaling factors was aimed at applying the principles set out in ISO 21238:2007 to the measurement of contaminated areas in decommissioning sites. In this paper, we report the progress made under MetroDECOM in identifying decommissioning matrices of specific relevance to nuclear decommissioning within the EU and selecting priority hard-to-measure radionuclides for further study.