Year
1989
Abstract
In an earlier work it was shown that in a triple tank system which is used in the planned German industrial scale reprocessing plant there exists an optimal time for inventory taking: It is that time where the catch tank is empty which means that the changing concentration of the solution entering this tank does not influence the concentration of the other two tanks. Since, however, the process area of the planned plant essentially consists of 3 triple tank systems, and since in general the catch tanks of these systems will not be empty at the same points in time, the question arises whether or not this poses a problem to near real time accountancy (NRTA). It has been pointed out many times that the main purpose of NRTA is the timely detection of losses or diversion of nuclear material. Since it is assumed that, e.g., once a year an inventory of the whole plant is taken such that losses or diversion can be detected with some probability at that time, here the question is how to guarantee the timely detection of early losses or diversion in view of the necessarily shifted partial inventories. In this paper it is shown quite generally that by use of appropriately defined balance statistics for the total material balance area detection time can be shortened considerably if some internal transfers are verified. In the concrete case of triple tank systems the problem has a very simple solution: Only some volumina of single tanks have to be verified at different points in time.