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International audience; This paper provides a link between the MUSE (MUltiplication avec SourceExterne) program performed at CEA-Cadarache in France, and the TRADE(TRiga Accelerator Driven Experiment) program performed at ENEA-Casacciain Italy. In both programs, extensive measurements were made to determinethe best methods for sub-criticality measurements in an accelerator-driven system.A very serious attempt was made to quantify the uncertainties associatedwith such measurements. While both MUSE and TRADE studied the methodsof sub-criticality determination, in fact the two systems are very different.MUSE was a fast system with MOX fuel (generation time around 0.5 μs), andTRADE was performed in a TRIGA reactor (generation time around 50 μs).This paper will summarize the important results of these two experiments,with the main purpose being to tie them together to attempt to draw genericconclusions that can be applied in the future to a real ADS.In addition, this paper will briefly discuss the next series of experiments thatwill continue this work in the U.S. (RACE, Reactor Accelerator Coupled Experiments),Belarus (YALINA), Belgium (GUINEVERE), and Russia (SAD,Sub-critical Assembly Dubna). MUSE and TRADE have contributed greatlyto our understanding of the uncertainties associated with sub-critical measurements,but there are still some gaps that must be covered. This paper willdescribe the gaps that exist, and demonstrate how the above future programswill fill in the missing information needed for the design of an actual ADSsystem in the future.

The TRiga Accelerator Driven Experiment (TRADE) to be performed in the existing TRIGA reactor of the ENEA Casaccia centre had the objective of coupling a spallation target, a proton accelerator and a sub-critical reactor core. On the way of the transmutation of minor actinides in dedicated facilities, the TRADE experiment represents the intermediate step between the validation of each component of an Accelerator Driven System (ADS), i.e. the spallation target, the high intensity accelerator and the sub-critical core, and the final facility aiming to incinerate radioactive nuclear waste. Measurements have been performed in the TRIGA - RC1 reactor of the ENEA Casaccia centre in the second semester of 2004 to characterize the neutron flux in a critical configuration. Gold and Indium samples were introduced in the core with the help of a "fast rabbit" pneumatic device. Bare samples and samples covered with Cadmium foils were successively irradiated to estimate the thermal and epithermal fluxes. Measurements have been carried out along a traverse of the core. Samples were put inside Aluminium shuttles travelling in stainless steel tubes. Trains composed of five shuttles allowed for simultaneous measurements in five different axial positions. γ spectrometry of the radioactive nuclides has been performed with two HPGe detectors.

International audience

TRADE (TRIGA Reactor Accelerator Driven Experiment) will be the demonstration of the coupling of a real spallation source with a sub-critical reactor. TRADE and its motivation are summarised. The experimental work plan of the campaign is presented. The first experiments with the accelerator are scheduled around 2006 or 2007. Some specifics of the TRIGA core are given and particularly about fuel burn-up. Core calculation results with Monte-Carlo and deterministic codes and rods worth obtained during the short campaign of fall 2002 are presented. The comparison between calculated results and this first experiment gives confidence for the follow-up work.

The three levels involved in the experimental validation of an Accelerator Driven System (ADS) are discussed. TRADE is referenced as the most important step toward the ADS demonstration. The types of measurements required to perform in TRADE are also discussed. The TRADE experiments are preferred as they have the ability of incorporating the feedback effects into the dynamics measurements in ADS and to address ADS operational, safety and licensing issues. The categories of the types of experiments performed are: start-up and shut down procedures, operation and monitoring of the system at steady state, monitoring of the time evolution of the reactivity, and practical coupling of an accelerator, a spallation target and the subcritical core.

This paper provides a comparison of the performance of an electron accelerator-driven experiment, under discussion within the Reactor Accelerator Coupling Experiments (RACE) Project, being conducted within the U.S. Department of Energy's Advanced Fuel Cycle Initiative (AFCI), and of the proton-driven experiment TRADE (TRiga Accelerator Driven Experiment) originally planned at ENEA-Casaccia in Italy. Both experiments foresee the coupling to sub-critical TRIGA core configurations, and are aimed to investigate the relevant kinetic and dynamic accelerator-driven systems (ADS) core behavior characteristics in the presence of thermal reactivity feedback effects. TRADE was based on the coupling of an upgraded proton cyclotron, producing neutrons via spallation reactions on a tantalum (Ta) target, with the core driven at a maximum power around 200 kW. RACE is based on the coupling of an Electron Linac accelerator, producing neutrons via photoneutron reactions on a tungsten-copper (W-Cu) or uranium (U) target, with the core driven at a maximum power around 50 kW. The paper is focused on analysis of expected dynamic power response of the RACE core following reactivity and/or source transients. TRADE and RACE target-core power coupling coefficients are compared and discussed.

The TRiga Accelerator-Driven Experiment (TRADE), to be performed in the TRIGA reactor of the ENEA-Casaccia Centre in Italy, consists of the coupling of an external proton accelerator to a target to be installed in the central channel of the reactor scrammed to subcriticality. This pilot experiment, aimed at a global demonstration of the accelerator-driven system concept, is based on an original idea of C. Rubbia. The present paper reports the results of some neutronic analyses focused on the feasibility of TRADE. Results show that all relevant experiments (at different power levels in a wide range of subcriticalities) can be carried out with relatively limited modifications to the present TRIGA reactor.