Year
1996
Abstract
A product tank weighing system has been installed in the TAME laboratory at the JRC Ispra.This tank, often denoted as a ‘D’ shaped vessel due to its geometric shape, has a volume of 400dm3 and served as the prototype tank for the development of similar tanks utilising a weighing technique for nuclear material accountancy and process control purposes. The original reasons for selecting a weighing technique are mainly due to an accuracy potential of 1 in 105, with advantages of no density fluctuations due to gas bubbles, no malfunction of dip tube systems e.g. blockages, leaks, no problem with inadequate bulk temperature measurement, no conversion from volume to mass with density measurement problems, which when taken altogether should ultimately lead to a reduction in MUF levels. A series of tests have been carried out with the tank and weighing system, in particular on commissioning of the tank in the ‘as found’ condition, i.e. no pipes attached, followed by an examination of the influence of pipe connections to the reference conditions. The effects of off-centre loading, i.e. changes in the centre of gravity during filling have also been examined. Modifications were subsequently proposed to the pipework installations, with optimisation of pipework clamping followed by re-calibration exercises. Initial results with process pipework attached show a repeatability of +/- 0.006% of 400Kg (the liquid weight in the tank).