Use of a new potentiostat/coulometer in the controlled-potential coulometric determination of plutonium

摘要

We evaluated a PAR 273 potentiostat and PAR 279 coulometer using iron as a stand-in for plutonium. Over 400 turns consisting of electrical checks, blanks, and iron solutions were made. Manual operation of the instrumentation produced precisions better than 0.1%. Computer control of the instrumentation produced precisions better than 0.1%. Computer control of the instrumentation using a PC and a program written in QuickBASIC produced precision of about 0.12%. The computer program automatically set up and controlled the instrumentation and recorded the data. The potentionstat's current autoranging function caused erratic coulometer results. Use of the PAR 273's low-pass filter (LPF) removed the amperometric end-point current noise, but it also biased the current. The PAR 273A's LPF filtered the noise without introducing a bias. The coulometer functions, such as current integration and communication interface, occasionally locked up after a current overrange condition. The occasional procedural error revealed that the potentionstat's ability to produce >1 A current can ruin the coulometer's impact circuitry, which is protected up to 0.2 A for current ranges