Oscillation experiments techniques in CEA MINERVE experimental reactor

The CEA is deeply involved in a research program (Material Testing Reactors, Zero Power Reactors) concerning the nuclear fuel advanced studies (actinides, plutonium), the waste management, the scientific and technical support of running French PWR reactors and EPR reactor, and innovating systems. In this framework, specific neutron integral experiments have been carried out in the critical facilities of the CEA Cadarache, such as MINERVE, EOLE and MASURCA. This paper deals with experiments in the MINERVE pool Zero Power Reactor. MINERVE is mainly devoted to neutronics studies, in view to improve the calculation routes by reducing the uncertainties of the experimental databases for nuclides arising in plutonium and wastes management. MINERVE experimental measurement programs are performed by using the oscillation technique. This experimental technique consists in a periodic insertion and extraction of samples containing the nuclide of interest in a well characterized neutron spectrum. The reactivity variation of the sample is compensated by a calibrated rotary automatic pilot using cadmium sectors. The normal accuracy for measurements of small-worth samples in MINERVE by using such a technique is about 3% for absolute reactivity worth, including the uncertainties on the material balance and on the calibration step. Reactivity effects of less than 1.5 cent can be measured. The OSMOSE and the OCEAN programs have been carried out since 2005 and will last until 2011. These programs aim at improving, in different neutron spectra, the absorption cross sections of respectively a majority of the separated heavy nuclides from ²³²Th to ²⁴⁵Cm appearing during the reactor and the fuel cycle physics, and of current and future types of absorbers as Gd, Hf, Er, Dy, Eu.