Franck BACHELET*, Luc Dujardin*, Sebastien Clouard*, Armelle Collardey*, Marc Theobald* Guillaume Jossens**, Christophe Mathonat**, Gary Etherington** * CEA, VALDUC, F IS-SUR-TILLE, France ** SETARAM Instrumentation, 7 rue de l’Oratoire, F CALUIRE, France LARGE NUCLEAR CALORIMETER FOR NON DESTRUCTIVE ASSAY ON 55 GALLONS TRITIATED WASTE DRUMS A new large calorimeter was developped by SETARAM and CEA Valduc for the nuclear waste quantification by calorimetry within drums having a volume bigger than 55 gallons (250 liters). The calorimeter is an active heat flux calorimeter based on a differential principle used to measure a wide range of power emitted by alpha and beta radioactive elements. This calorimeter is based on a new patented principle and it guarantees best security for the users with minimum handling of the sample. The system is air cooled and includes a new optimized software for direct measurement of the quantity of nuclear material. As part of the management of tritiated wastes, CEA Valduc has performed the tests of qualification of the calorimeter with ghost drums. Some results will be presented in order to show its measurement capacities and particularly its precision and accuracy. ABSTRACT FEATURES OF THE CALORIMETER Institute of Nuclear Material Management 55th Annual Meeting - July , Atlanta, Georgia USA DESIGN (patented technology) -Opening system with two electrical half-shells -Safety and easy handling loading -2 thermal barrier and 2 insulating layers which filter and eliminate thermal disturbances -1 large measurement cell which contain waste drums (up to 55 gallons) -No reference cell (ghost reference) -No water-cooled (air bath) -No air-conditioned laboratory -Be moved on road -Optimized electronic and industrial software (Calisto LVC) 100 liters drum200 liters drum MEASUREMENT AND RESULTS PRINCIPLE OF THE HEAT FLUX CALORIMETER : Measurement of an active isothermal and differential heat flow EXPERIMENTAL RESULTS Environmental conditions 15°C < T < 28°C 40% < H < 90 % Measurement cell Volume max385 liters Sample diameter max630 mm Sample height max1380 mm Thermal block temperature30 °C ± °C DetectorsPeltier elements Power range measurement3 mW – 3.5 W Calorimeter LVC W (SETARAM) Height3.01 m Length4.26 m Width2.40 m Weight12 T Working Temperature °C Power supply V / 50–60 Hz Power Range3 mW – 3.5 W FE200 container (200 liters) Thermal Block (30 °C) Insulation layers Thermal Barrier (27 °C) Cold barrier (24 °C) Joule effect device FunctionCalibration PrincipleResistive heater Geometry Adaptable to the drum dimension Power Range0 – 3.5 W Power variance-0.03 % to 0.10 % Accuracy 10 mW0.03 mg 3 H15 % 500 mW0.31 mg 3 H2,5 % 1000 mW3.08 mg 3 H2 % 3000 mW30.86 mg 3 H2 % Limit of Detection 9 mW (28 mg 3 H) Measurement time Variable from 3 days to 7 days CONCLUSION → First large volume calorimeter (over 100 liters) designed for tritium accountability of waste drums → Very good results of accuracy 3 g 3 H) and limit of detection (27 mg 3 H) → Measurement time depends on many parameters like thermal environmental conditions, sample weight or tritium range FE 200 container 400 kg Calibration Thermal regulation of the measurement cell +/ °C Heat Flow Room temperature Calibration Signal (µV) = f(t) Effective specific power of Tritium (W/g) Sensitivity (µV/mW) Tritium 0,324 W/g Tritium conversion Thermal Activity (Watt) Thermal heat Flow Heating Range Power (mW/g) Americium Plutonium Human Tritium Heat emission  Tritium 3 H → 3 He + β - T 1/2 = years A m = Bq/g E βMax = 19 keV (100%) E βAv = 5.7 keV M = uma Seuil décision 2*S co Tritium mass (g) Limit of detection (g) → Absolute method for tritium accountability → High accuracy and repeatable method → No sample preparation → No destructive assay → No dependence on sample geometry → No matrix effect and no distribution effect → Long measurement time (many days) White sample signal (µV) Sensitivity 168,8 µV/mW µV t mV