Building the Casaccia gamma field. Nuclear energy, Cold War and the transnational circulation of scientific knowledge in Italy (1955-1960)

The article will focus on the mutagenesis programme in agriculture implemented by the Italian Atomic Energy Commission, starting from 1955, through the establishment of a specific technological and experimental system: the so-called "gamma field", a piece of agricultural land with a radioisotope of Cobalt-60 at the centre. The Cobalt-60 would emit constant radiation, which would bombard the specimens planted in concentric circles around the source, inducing genetic mutations. The Italian gamma field went into operation in January 1960 at the Casaccia Laboratory, about twenty miles north of Rome, with a radiation device made available by the US Government for the Atoms for Peace programme This article will analyse, first of all, how the American experimental model of mutation breeding was translated into the Italian context, becoming instrumental for the establishment of plant genetics within the local academic system; secondly, it will describe how the sociotechnical imaginary embodied by the gamma field was part and parcel of this process of disciplinebuilding and scientific demarcation.

Review Microstructure of Nickel-Based Single-Crystal CMSX-4 Superalloy after Electrochemical Machining

A special position has been created for using the nickel-based single-crystal CMSX-4 superalloy at high temperatures due to the improved mechanical properties of this material and the absence of grain boundary in the crystal lattice. Also, electrochemical machining can be an effective method for machining this superalloy due to its unique performance in metal machining, like creating stress-free surfaces, high-level surface smoothness, and machining of complex geometries. This single crystal superalloy's microstructure consists of three phases: Gamma, Gamma prime, and a bit of carbide. Gamma prime is distributed cubically and homogeneously in the Gamma field without any boundaries and as a single crystal. It is essential not to change the microstructure after the production process or machining. In the present research, electrochemical machining was performed on CMSX-4 single crystal superalloy. The workpiece's microstructure was then investigated before and after electrochemical machining using scanning electron microscopy and EDS analysis from two sides. No changes were seen in CMSX-4 infrastructure after electrochemical machining EDS analysis and Images.

Measurement of prompt gamma field above the VR-1 water level

Pool-type reactors are an excellent source of high energy photons without neutrons because the water above fuel acts as an outstanding neutron shielding, whereas for high energy photons, it is nearly transparent. The absence of neutrons is a valuable property essential for testing semiconductor detectors because they are sensitive to neutrons, which might cause their damage. The high energy gammas are worth studying because they are responsible for radiation induced heating of reactor internal components in energy producing reactors, which might lead to their radiation induced damage by void swelling. At this effect, the helium produced in (n,α) reactions influenced by locally increased temperature clusters into bigger bubbles, which are increasing material volume, and therefore changing the geometry of internals. The referred method could be utilized e.g. for resource exploration by detecting prompt capture gammas. The prompt gamma field was measured at the VR-1 reactor with two different cores and water levels. The stilbene measurements showed relatively good agreement with the spectrum shape computed by MCNP6.2. An important result is a confirmation that the stilbene deconvolution matrix can be used with a rotated crystal. The testing measurement with HPGe detectors showed a possibility for measurement in such type of geometry.

Geophysical survey at the southern end of the Degtyarsky pyrite deposit

Research aim is to study features peculiar to geophysical fields over the main geological features of the southern part of the Degtyarsky pyrite deposit at the Middle Urals. Methodology. Electromagnetic survey included symmetrical electric profiling (SEP) with ERA-MAX equipment (ERA Research and Production Enterprise, St. Petersburg) and rapid audio-magnetotelluric sounding (ATMS) with OMAR-2m wideband receiver (Institute of Geophysics UB RAS, Ekaterinburg). Magnetic survey was carried out with the help of the proton procession magnetometer GSM-19T (GEM Systems, Canada), gamma field survey was carried out with a survey meter SRP-68-01 (Electron, Zhovti Vody). Results. According to the results of observational analysis, high-quality sections of electrophysical parameters of the environment were constructed at the parametric profile together with the charts of other geophysical fields. The studies have shown significant changes of resistivity and potential fields anomalies over various geological features of the ore field. Summary. Geophysical indications of border line of the main geologic features have been determined. Excessive electrical conductivity of ore control tectonic structures and radiation anomaly have been revealed in the promises of the ore body, which can serve a prospecting criterion for a similar ore body. Geophysical results are well within the existing geological data on the Degtyarsky mine.

Characterization of the gamma flux in a tangential channel of the CENM TRIGA MARK II research reactor

The CNESTEN (National Center for Energy Sciences and Nuclear Technology, Morocco) operates a TRIGA Mark II reactor, which can reach a thermal maximum power at steady state of 2 MW. In reactors devoted to research and experiments, it is mandatory to characterize the neutron and photon fields in the irradiation positions. Together with a computational model of the core, it ensures the ability to reach the requested uncertainties when performing experiments, such as detectors testing, irradiation for hardening or nuclear data measurements. The neutron field of different irradiation positions has been characterized by dosimetry techniques and compared to the MCNP full model of the reactor. Preliminary photon propagation calculations are also performed with this model, but up to now, no experimental validation of the results exists. The aim of the newly set collaboration between CEA and CNESTEN is to characterize the gamma field of these positions. The first position investigated is the part of the NB1 tangential channel closest to the core. Among gamma measurements techniques, and according to the constraints arising from using this channel, it was chosen to use thermos- and optically stimulated luminescent detectors. This paper presents the experiments carried out in September 2018 as well as their results. Three detectors types were used: TLD400 (CaF2:Mn), TLD700 (7LiF:Mg,Ti) and OSLD (Al2O3:C). Measurements were performed in several steps: background measurements, transient measurements (divergence phase + SCRAM), and irradiation at steady state. In the end, these measurements will provide a dose as well as a gamma flux value for this position.

JSI TRIGA neutron and gamma field characterization by TLD measurements

A well characterized radiation field inside a research nuclear reactor irradiation facilities enables precise qualification of radiation effects to the irradiated samples such as nuclear heating or changes in their electrical or material properties. To support the increased utilization of the JSI TRIGA reactor irradiation facilities in the past few years mainly on account of testing novel detector designs, electronic components and material samples, we are working on increasing the neutron and gamma field characterization accuracy using various modeling and measurement techniques. In this paper we present the dose field measurements using thermo-luminescent detectors (TLD’s) with different sensitivities neutron and gamma sensitivities, along with multiple ionization and fission chamber. Experiment was performed in several steps from reactor start-up, steady operation and a rapid shutdown, during which the ionization and fission chamber signals were acquires continuously, while the TLD’s were being irradiated at different stages during reactor operation and after shutdown, to also capture response to delayed neutron and gamma field. The results presented in this paper serve for validation of JSI designed JSIR2S code for delayed radiation field determination, initial results of its application on the JSI TRIGA TLD measurements will also be presented.

Measuring the equivalent dose rate over the Shelter object after completion of the New Safe Confinement

An experiment on measuring the equivalent dose rate over the Shelter object after the completion of the construction of the New Safe Confinement is described. Measurements of the gamma radiation were performed in the time of commissioning of the New Safe Confinement with the help of the sensor installed on its Main Cranes System. The carriage with a sensor was moved by a chaotic trajectory so the method of missing data interpolation was proposed. As a result, a cartogram of the distribution of the gamma field at the level of movement of the bogies of the Main Cranes System of the New Safe Confinement is provided in this paper.

Gamma-heating and gamma flux measurements in the JSI TRIGA reactor, results and prospects

The neutron field of various irradiation positions of the TRIGA Mark II reactor of the Jožef Stefan Institute has been thoroughly characterized by neutron activation dosimetry and miniature fission chambers techniques. In order to have a fully validated calculation scheme to analyze and plan experiments, the gamma field also has to be experimentally validated. The 10-year long collaboration between CEA and JSI is a perfect framework to carry out such a study, and measurements of the gamma field started in late 2016. Several measurement techniques were investigated in in-core and ex-core positions. On-line measurements were carried out using miniature ionization chambers manufactured by the CEA and PTW Farmer ionization chambers. Positional dependence was studied, showing a decrease in the delayed gamma contribution to the total gamma flux with increasing distance from the reactor core center. To characterize the gamma dose in the core, as well as in the periphery, thermo- and optically stimulated luminescent detectors were tested. These detectors are commonly used at CEA to measure the gamma dose in a given material in order to study the nuclear heating in various core elements (control rod, baffle, structural material). Different filters were used in order to assess an integrated dose ranging from a few Gy up to several kGy. The feasibility of such measurements demonstrates the complementarity between measurements with dosimetry and ionization chambers from low to very high gamma-dose environment, such as in material testing reactors.

SIMULATION OF DOSE DISTRIBUTION IN VICINITY OF CLOUD OF CONTAMINATED AIR LEAKAGE FROM SEVERE NPP ACCIDENT

Method of Monte Carlo simulation of gamma radiation fields in the vicinity of the cloud of air contaminated by the radionuclides from emergency leakage from nuclear power plant was designed and tested. Air kerma rates distributions as well as gamma field spectral distributions were calculated for the Gaussian cloud model, different atmospherical conditions and emergency scenarios source terms. Based on this model, the radiation doses in the aerial vehicle (helicopter) and its shielding properties in the radiation fields in cloud vicinity were evaluated with an aim to prepare a method providing data for planning adequate radiation protection of the personnel during airborne monitoring/interventions.

Thermoluminescence dosimetry of mixed neutron – gamma fields

The method of measurement dosimetry in neutron – gamma field by using CaSo4 : Dy (PTFE) disc which has a diameter of 1.3mm and thickness of 0.2mm and using hydrogenated material as a converters of neutron to recoil protons (n-p) reaction, the discs were irradiated by neutron source (241Am-Be) with flux of 4.5?105 n/cm2s for different time to obtain different dose. The TL signals, which we have been obtained by using the converters, are increases to 71%. So we can resolve the neutron and gamma in mixed field.