A. Borio di Tigliole

Performance of the 10 m 3 ICARUS liquid argon prototype

Abstract We report on the performance of a liquid Argon Time Projection Chamber, operating in a 10 m 3 cryostat. This device built in the framework of the ICARUS T600 programme to serve as a full test facility for the adopted cryogenics and mechanical solutions, was successfully tested in 2000 as the last step before the tests of the first 600 t ICARUS module 1 year later. In a final run at the Gran Sasso Laboratory, whose outcome provides the main subject of this paper, also the readout and imaging capabilities of the installed wire chamber and the overall performance of the detector have been successfully tested.

Ultra Sensitive Neutron Activation Measurements of {sup 232}Th in Copper

Copper, thanks to its low content in radioactive contaminations, is a material widely used for shielding, holders and other objects close to the sensitive parts of the detectors in many experiments in rare event physics. This implies that tools able to reach sensitivity of the order of <10−12 gram of contaminants per gram of copper are of crucial importance. A methodology based in Neutron Activation Analysis (NAA) has been developed to obtain an extremely high sensitivity in the analysis of 232Th in copper samples. A detection limit of 5×10−13 g 232Th/g Cu has been achieved through the irradiation of 200 g of copper sample which subsequently was radio‐chemically concentrated using nitric acid and then actinide resin from Eichrom Inc. Several elutions were performed with various inorganic acids to concentrate the 232Th activation product (233Pa) from the copper matrix and to also eliminate the radioactive background induced by the neutron bombardment to reach higher sensitivity.

Non-destructive diagnostics of thin fissile layers

We have developed a non-destructive nuclear technique useful for the diagnostic of thin layers of fissile element. The method is based on the correlation between the fission fragment energy losses and the distortion of the energy spectrum of the alpha-particles emerging from the layer itself. We have also measured the sputtering rate of atoms from a fission layer which can be the cause of an important degradation in a working apparatus.

Measurement of fission fragments energy loss

Abstract The mean energy of 252 Cf fission fragments emerging from an absorber and the determination of the capture rate in the absorber itself have been measured using two independent and complementary nuclear techniques. The results can be applied to the measurement of the energy self-absorption in a non-zero thickness source and can be used to validate simulation programs.

Fission products detection in irradiated TRIGA fuel by means of gamma spectroscopy and MCNP calculation

Aim of this work was the detection of fission products activity distribution along the axial dimension of irradiated fuel elements (FEs) at the TRIGA Mark II research reactor of the Technische Universität (TU) Wien. The activity distribution was measured by means of a customized fuel gamma scanning device, which includes a vertical lifting system to move the fuel rod along its vertical axis. For each investigated FE, a gamma spectrum measurement was performed along the vertical axis, with steps of 1 cm, in order to determine the axial distribution of the fission products. After the fuel elements underwent a relatively short cooling down period, different fission products were detected. The activity concentration was determined by calibrating the gamma detector with a standard calibration source of known activity and by MCNP6 simulations for the evaluation of self-absorption and geometric effects. Given the specific TRIGA fuel composition, a correction procedure is developed and used in this work for the measurement of the fission product Zr95. This measurement campaign is part of a more extended project aiming at the modelling of the TU Wien TRIGA reactor by means of different calculation codes (MCNP6, Serpent): the experimental results presented in this paper will be subsequently used for the benchmark of the models developed with the calculation codes.

Study of a new Automatic Reactor Power Control for the TRIGA MARK II reactor at University of Pavia

The installation of a new Instrumentation and Control (I&C) system for the TRIGA MARK II reactor at University of Pavia has recently been completed in order to assure a safe and continuous reactor operation for the future. The intervention involved nearly the whole I&C system and required a channel-by-channel component substitution. One of the most sensitive part of the intervention concerned the Automatic Reactor Power Controller (ARPC) which permits to keep the reactor at an operator-selected power level acting on the control rod devoted to the fine regulation of system reactivity. This controller installed can be set up using different control logics: currently the system is working in relay mode. The main goal of the work presented in this paper is to set up a Proportional-Integral-Derivative (PID) configuration of the new controller installed on the TRIGA reactor of Pavia so as to optimize the response to system perturbations.