OSIRIS REACTOR - Centre de Cadarache - CEA

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26EXPERIMENTAL DEVICESCEA••• NUCLEAR ENERGY AUTHORITYTANOXOSThe TANOXOS device is designed for fuel irradiation in order to develop new fuels withoptimised microstructures and compositions to limit the release of fission gases. The deviceis located on the periphery of the reactor and can be inserted or withdrawn, withthe reactor in operation. It is cooled by forced convection by the water from the reactor pool.The displacementsystem.Thanks to its design, this device makes it possible to: reach high burnup rates in reasonable times with thermal conditions close to thoseof power reactors, thanks to the small dimensions of the fuel pellets, adjust the power on the experimental fuel elements by moving the device in relationto the core of the reactor (maximum linear power of 520 W/cm).The control of the irradiation temperature is by thermocouples located in the core ofthe fuel rods.The TANOXOS device can house 6 fuel rods, with a maximum diameter of 4.95 mm and amaximum length of 100 mm.Each fuel element is contained in an external container, which acts as a barrier with respectto the water of the reactor pool. Each container is instrumented with temperature and pressuregauges and is filled with helium; sampling is possible outside irradiationperiods. The overbraided containers can be connected to an removable auxiliary controlcircuit to pressurize and depressurise the container, as well as control the pressure pick-ups and the gas sampling.The “fuel element and overbraided container” unit constitutes an experimental load.The 6 experimental loads are installed in a barrel, the function of which is to homogenize the fluences on each fuelelement by rotating the unit. The barrel with its 6 experimental loads is placed in a sample-holder. A sleeve placed aroundthe sample-holder is used to cool the experimental loads by channelling water on the one hand, and on the other, to supportthe collectrons for constant measurement of the neutron flux.IRISthickness (µm)Plate lengthChange in thickness of a platebetween each irradiation cycle.The IRISdevice.The IRIS device has been designed toirradiate fuel plates for experimentalreactors. It has the same external geometry asa standard OSIRIS fuel element and is placedin the core of the reactor. The device is cooledby the water of the primary circuit. Manufacturedout of aluminium alloy, it is equippedwith a latch in its upper section to avoid platemovement due to the effect of the ascendingcirculation of water. The latch can be removedto extract the plates during reactor shutdownsin order to carry out dimensional measurementsof swelling and visual inspections.
EXPERIMENTAL DEVICESNUCLEAR ENERGY AUTHORITY ••• CEA27The IRIS device can be loaded with 4 different fuel plates, separated by inert aluminium plates.The dimensions of the experimental plates are 641.9 mm long, 73.3 mm wide and 1.27 mm thick. The maximum massof uranium U tot per plate is 500 g and that of the Uranium 235 is 100g.The principal characteristics of the IRIS device are as follows: reusable device, loading and unloading of the plates underwater, mixed loading of new plates with plates already irradiated, a wide range of irradiation conditions depending on the position chosen in the core of the reactor, an increase in thickness of the plates of 0.25 mm considered as the authorized limit for proper cooling during irradiation.The plates irradiated in this way are subjected to a dimensional check on each cycle on a dedicated measurement bench.BARITONIn order to validate the referencecurve of the toughness of irradiatedtank material, in the ductile/brittletransition range, the BARITON devicederived from the IRMA furnace rigcan house up to 4 CT50 test specimens.This device occupies 9positions on the periphery of the coreof OSIRIS under a neutron flux closeto 2 10 16 n.m -2 .s -1 .Each test specimen is surrounded by4 thermocouples in order to reconstitutethe profile and the gradient in therecess of the testspecimen. Eighteenheating elements are used to reach atemperature of 295 ± 6°C at the bottomof the recess.The BARITONsample-holder.Support bars forthermocouplesSpacersupportsfor doseintegratorsPower supplies +instrumentationRemovablecovers for heatingelementsholdersInstrumentation of the devicesInstrumentation is one of the key parameters for the performance of the experiments undertaken in the reactor. This is becauseduring irradiation, various physical parameters must be measured on-line in a reliable and precise way. The experimental devicesimplemented at OSIRIS are equipped with various sensors and measurement systems, according to need.The instrumentation usually used include: measurements of the nuclear radiation characterizing the irradiation (neutron flux, heating or gamma radiation) usingcollectrons (SPND), activation dosimeters, calorimeters or sub-miniature fission chambers, temperature measurements by thermocouples, placed on or near the samples, but also in the core of the irradiated nuclearfuels,
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OSIRIS REACTOR - Centre de Cadarache - CEA

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