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International audience; One of the main experimental equipment under construction within the Jules Horowitz Reactor isthe LORELEI (Light water One Rod Equipment for LOCA Experimental Investigation). The aim ofthis test device is to study the thermomechanical behavior of the cladding and the fuel rod in order todetermine the radiological consequences in the case of a Large Break LOCA (Loss-Of-Coolant Accident)accident. In order to design appropriately this device it is important to simulate its behaviorin normal operation or in incidental and accidental situations by using a thermal-hydraulic two-phaseflow software. In this paper, we present two different numerical tests corresponding to the two mainworking conditions of the LORELEI device. The first test simulates the working condition of there-irradiation phase, when the device is filled with water and the fuel rod cooled in a natural convectionloop. This test is thought to provide temperature profiles and velocities in the thermosiphoncomponent, both in single and two phase regime, and to determine the power threshold needed tolimits the thermosiphon working conditions. The second test, consecutive to the re-irradiation phase,reproduces the LOCA sequence with the device in a gas environment (steam, helium and hydrogen).For this case, where high temperatures occur, a new dedicated radiative heat transfer module isintroduced. The objective of the simulation is to obtain representative thermal maps of all significativecomponents from the beginning of the LOCA sequence up to the high temperature plateau. Weperform CATHARE-2 computations and compare the results with CFD corresponding simulations.

The aim of the GENII-LIN project was to develop an open source multipurpose health physics code running on Linux platform, for calculating radiation dose and risk from radionuclides released to the environment. The general features of the GENII-LIN system include [1] capabilities for calculating radiation dose both for acute and chronic releases, with options for annual dose, committed dose and accumulated dose [2] capabilities for evaluating exposure pathways including direct exposure via water (swimming, boating, fishing), soil (buried and surface sources) and air (semi-infinite cloud and finite cloud model), inhalation pathways and ingestion pathways. The release scenarios considered are: - acute release to air, from ground level or elevated sources, or to water; - chronic release to air, from ground level or elevated sources, or to water; - initial contamination of soil or surfaces. Keywords: radiation protection, Linux, health physics, risk analysis.

The neutron interaction cross sections in the energy range below 20 MeV for 232Th have been completely revised starting from both recent experimental data and theoretical results given by an updated version of the CIRCE, POLIFEMO and PENELOPE chain codes for direct reaction, compound nucleus and direct scattering calculations. The angular distributions for inelastic scattering by the first three excited levels, taking into account the nuclear deformation up to the hexadecapole term, have been calculated and compared with experimental results. The new data set has been tested in calculiations performed on the THOR fast criticality experiment. The transport calculations were carried out in spherical geometry through the XSDRNPM transport module of the SCAMPI Data Processing System. The results were compared with the corresponding ones obtained with other 232Th data files (ENDFB VI-3, JEF-2.2 and JENDL-3.2).

The breakdown phase in a Plasma Focus (PF) device is not yet a well-understood phenomenon, even if widely known to be of great importance in the subsequent evolution of the discharge. A Particle-In-Cell (PIC) method coupled with a Monte-Carlo-Collision (MCC) module has been developed to study the time evolution of electron density and Electron Energy Distribution Function (EEDF) up to few tens of nanoseconds. An innovative dynamic control on the simulation particles number has been introduced. A merging technique based on a Sorted Hierarchical Agglomerative Sub-Clustering is performed to collapse clusters of particles in the phase space. Moreover, in order to avoid particles depletion in the cathode-fall region, an additional splitting procedure will be discussed: it is intended to preserve a sufficiently high sample representativeness for the stochastic secondary emission events and to limit local fluctuations in the electric field solution. The algorithms not only accelerate the numerical solution and guarantee better statistics, but are also intended to preserve the position, charge-mass, direction of flight, momentum and energy of the starting set of particles. As it arises from simulations, the EEDF development shows a deviation from the Maxwellian distribution function: an anomalous number of high-energy electrons enhances the ionization rate of the working gas towards the development of a localized plasma sheath on the insulator sleeve at the electrodes closed end. After few nanoseconds from the beginning of the discharge, a fundamental role is played by secondary electrons produced at the cathode wall by photoelectric effect due to molecules excited states de-excitation. The numerical model describes the breakdown ignition more precisely than existing hydrodynamic ones.

GENII-LIN is an open source multipurpose health physics code running on Linux platform, that allows calculating radiation dose and risks from radionuclides released to the environment. The general features of the GENII-LIN system include: [1] capabilities for calculating radiation dose both for acute and chronic releases, with options for annual dose, committed dose and accumulated dose; [2] capabilities for evaluating exposure pathways including direct exposure via water (swimming, boat, fishing), soil (buried and surface sources) and air (semi-infinite cloud and finite cloud model), inhalation pathways and ingestion pathways. The release scenarios considered are: • acute release to air, from ground level or elevated sources, or to water; • chronic release to air, from ground level or elevated sources, or to water; • initial contamination of soil or surfaces.

Experiments in the past five years have demonstrated production of short-lived radioisotopes with a Plasma Focus device, using the so-termed Endogenous Mode. So far radioisotope activities of only a few microcuries have been obtained from single discharges in small scale Plasma Focus machines (capacitor bank energies of approximately 7 kJ). It is expected that higher activities could be obtained with larger bank energies, operating at high pulse repetition rates, e.g. 1 Hz. However, many scientific and technological issues must be addressed for a high-energy Plasma Focus device to run at one pulse per second. Aim of this paper is to present preliminary results pertaining to the plasma, electrical, fluid-dynamical, thermal, material and mechanical design of a 150 kJ Plasma Focus, capable of a repetition rate of 1 Hz, that will be operated at 30 kV with a 350 microFarad capacitor bank and a maximum total current of 1.5 MA. This device will be used to breed 18-F for the synthesis of drugs used in positron-emission medical examinations, such as FDG for PET.

La presente invenzione concerne un’apparecchiatura per la produzione di fasci di elettroni e di raggi X per trattamenti di radio terapia interstiziale ed intra operatoria più comunemente denominata IORT (Intra Operative Radio Therapy). Più particolarmente l'invenzione concerne un'apparecchiatura IORT che utilizza una macchina tipo Plasma Focus, associata ad una opportuna guida per elettroni da convogliare direttamente in prossimità del tessuto da trattare tramite irraggiamento elettronico o fotonico a bassa energia ed altissimo rateo di dose (dose rate).