Massimo Morichi

Nuclear measurement technologies & solutions implemented during nuclear accident at Fukushima

Fukushima accident imposed a stretch to nuclear measurement operational approach requiring in such emergency situation: fast concept development, fast system integration, deployment and start-up in a very short time frame. This paper is describing the Nuclear Measurement that AREVA-BUNM (CANBERRA) has realized and foresight at Fukushima accident site describing the technical solution conceived developed and deployed at Fukushima NPP for the process control of the treatment system of contaminated water. A detailed description of all levels design choices, from detection technologies to system architecture is offer in the paper as well as the read-out and global data management system. This paper describes also the technical choices executed and put in place to overcome the challenges related to the high radiological contamination on site.

Novel Nuclear Measurements Technologies for Safety and Security

A series of novel nuclear measurements technologies such as hybrid gamma spectroscopy and real time 3D-contamination modelling have been developed recently at AREVA towards Safety and Security applications as result of direct experiences and related to Fukushima site remediation project.

VERDI: A versatile readout ASIC for radiation detectors

In this work we present the circuit VERDI (VErsatile Readout for Detector Integration), an integrated circuit developed for the readout of different families of radiation detectors, from nitrogen-cooled Ge and Si(Li) detectors, to silicon drift detectors (SDDs), scintillation detectors, photomultipliers tubes and others. The circuit may represent a suitable solution when a compact integration between a multi-element detector and the front-end readout is needed to realize a compact and low-power detection module. The circuit includes 8 channels, each one composed by a charge preamplifier, a shaping amplifier, a gain stage, a baseline holder and a peak stretcher. An on-chip selector provides at the output of each channel the waveform of a specific stage, including an RC integrator for external digital processing of the signal. Alternatively, the 8 channels may be multiplexed on a single output. Different settings, like gain, shaping time, preamplifier compensation and others, may be externally programmed by SPI accordingly to the specific detector in use. Only the input JFET, feedback capacitor and reset device are left external to the ASIC, and must be chosen specifically for each detector. The results of preliminary experimental characterization of the circuit when used with different detectors are presented in this work.

A novel technique for trace actinides spectrometry directly in water samples

Vulnerability of drinking water distribution systems which would have major public health, economic and psychosocial consequences, has become a big concern to governmental agencies and water supply authorities. In case of an extremely alerting situation, such as Fukushima, the alpha emitters in water are probed on samples after very long chemical operations and time for the delivery of results extends over several days. The main objective of the ActiFind project is the realization of a high sensitivity alpha particles sensor working into water for the rapid detection and identification of traces of actinides at the 1 Bq/L level, after a short electro precipitation step. A 200 μm thick BDD layer is deposited on a CANBERRA PIPS detector. Under low cathodic current density, nitrate reduction occurs and produces a layer of (OH-) at the BDD surface and solid actinides hydroxides are accumulated at the entrance window of the PIPS sensor. After deposition, the ActiFind sensor is directly connected to a spectrometry chain. The coupling of the system to an integrated microfluidic F.F.E. platform has been developed in order to render the system compatible with more complex aqueous solutions in real environments containing interfering ions or substances. Further extension of the system will explore the possibility to use it as a decontaminating system on a scale up basis. The ability to perform alpha spectrometry directly in liquid media at trace levels constitutes a real breakthrough. Bq/L range is reachable within 10 minutes, opening the field to the development of a portable system with low energy requirement, and enabling real time monitoring of media at risk. This new technology can be used in the analysis of water used for cleaning surfaces in fuel reprocessing plants, sampling of environmental water around waste storage facilities, analysis of water samples after a nuclear accident or in the Mining sector where water quality should be assessed in the surrounding area.

Novel real-time 3D radiological mapping solution for ALARA maximization, D&D assessments and radiological management

Good management of decontamination and dismantling (D&D) operations or maintenance activities in contaminated or irradiating zones requires perfect radiological knowledge of the radioactive environment in order to optimize personnel dose and minimize of waste volume; this knowledge itself must be acquired safely and securely in a time-saving way. Additionally, Fukushima accident has imposed a stretch to the nuclear measurement operational approach required in such emergency situation: fast deployment and intervention, quick analysis and fast scenario definition. AREVA, as return of experience from its activities carried out at Fukushima and D&D sites, has developed a novel multi-sensor solution as part of its D&D research, approach and method, a system with real-time 3D photorealistic spatial radiation distribution cartography of contaminated premises. The system may be handheld or mounted on a mobile device (robot, drone, e.g.). In this paper, we will present our current development based on a SLAM technology (Simultaneous Localization And Mapping) and integrated sensors and detectors allowing simultaneous topographic and radiological (dose rate and/or spectroscopy) data acquisitions. This enabling technology permits 3D gamma sources cartography in a reconstructed volume in real-time.

Spectroscopy identification performance enhancement of a novel CZT/CsI hybrid system

New hybrid spectroscopic systems directly combine spectra from detectors with very different energy resolutions, accommodating standard analyses of the output hybrid spectrum. Simulations of a hybrid system consisting of a 2 or 4 cm3 cadmium zinc telluride detector combined with a 32.8 cm3 CsI(Tl) were evaluated for identification performance. 29 nuclides of interest for security applications were simulated as singles and unique pairs, producing 435 spectral simulations at live times of 3, 10, 30, 100 and 300 seconds. The nuclides were modeled as point sources at 25 cm with activities that provide an interesting range of statistical significance for the range of counting times. Standard nuclide identification analyses were applied to the component detectors as well as the hybrid combination. Tallies of the results were used to calculate true and false identification rates. The hybrid system was shown to provide an identification performance benefit, consistently achieving performances closest to ideal relative to the separate component detectors. The hybrid approach enables the consideration of a greater variety of measurement system solutions in terms of cost and performance.