Analytical investigation and experimental application of the source modulation technique to measure ρ/βeff\rho/\beta_{eff}

In recent years great interest has been displayed, worldwide, for Accelerator Driven Sub critical reactors (ADS) to incinerate the minor actinides generated by the existing energy producing reactors. In sub critical systems, the effective neutron multiplication factor is lower than 1.0 and the neutrons otherwise required to maintain the chain reaction, can be put to other uses, in particular, the destruction of nuclear wastes such as minor actinides (MA). One of the major advantages of such ADS systems is that it can be operated with very high M.A content without jeopardizing the overall safety due to a small effective delayed neutron fraction, a small Doppler temperature coefficient and possibly also a large void coefficient depending on the chosen coolant. This enhanced safety however prerequisites at all time a sufficient subcriticality margin. Reliable reactivity monitoring techniques are hence required to achieve this goal. The MUSE-4 program is a series of low power experiments carried out at the CEA-Cadarache MASURCA facility to investigate the various methods leading to the measurement of the reactivity level and associated kinetic parameters such as the effective delayed neutron fraction. The aim of this paper is to present the results obtained with a method which directly gives the ratio, for a sub critical assembly, between the reactivity ρ and the effective delayed neutron fraction βeff. By combining these results to those obtained with the kp-method for the prompt neutron multiplication coefficient, we have access to the parameters which govern the prompt and the slow kinetics of a sub critical assembly. These parameters can be obtained without reference to any calibration measurement in critical configuration. It opens the way to the control of larger sub critical demonstrators which are operating with fuels which cannot be used in critical reactor, and, thanks to sub criticality, which are characterized by a deterministic safety

Nuclear data activities at the NEA Data Bank

The OECD Nuclear Energy Agency (NEA) Data Bank is an international centre of reference for its member countries with respect to basic nuclear tools, such as computer codes and nuclear data. The Data Bank is part of an international network of data centres in charge of the compilation and dissemination of basic nuclear data. The NEA nuclear data services include the collection of data, validation and distribution of the Nuclear Data libraries via the NEA website, offering easy access to databases containing bibliographical and experimental information, as well as evaluated libraries, e.g., the Joint Evaluated Fission and Fusion (JEFF) library. The selection and distribution of chemical thermodynamic data for radioactive waste management applications is the subject of the Thermochemical Database Project (TDB), supported by 17 organisations in 12 member countries and co-ordinated by the NEA Data Bank. In support of data evaluation, and generation of project oriented data libraries, relevant computer codes in the field of nuclear models, experimental data processing and evaluated data processing are made available to experts with the support of the member countries. Large collections of benchmark experiments for data and code validation are also available from the NEA in areas such as criticality safety (ICSBEP), radiation shielding (SINBAD), fuel performance (IFPE) and reactor physics (IRPhE). The NEA Working Party on international nuclear data Evaluation Co-operation (WPEC) provides a framework for co-operative activities between the six major evaluation projects (BROND, CENDL, ENDF, FENDL, JEFF and JENDL)

Analytical investigation and experimental application of the source modulation technique to measure rho/b-eff

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