Determination of nitrogen in PuO2-UO2 mixed oxide with fusion-TCD method

Nitrogen in plutonium and uranium mixed oxide has been determined by several different methods. In the classical Dumas method, nitrogen is measured volumetrically. Other procedures are modifications of the Kjeldahl method in which nitrogen is converted to ammonia. All these methods are accompanied with the same problems in which the analysis takes usually 2 or 3 days with waste solutions generated. So far, the authors have tried to determine nitrogen in PuO2-UO2 mixed oxide with an improved dry process, in which an impulse furnace is used to heat the sample in a graphite crucible under a helium atmosphere. Nitrogen released from the sample were separated from other gases (i.e., a large amount of carbon monoxide, very small amount of hydrogen etc.) by a combination of original two moleculer sieve columns and pre-cut system. Separated nitrogen was then detected on the basis of thermal conductivities. (author)