The evaluation of the behaviour of sulphur 35 in the coolant circuit of a typical gas cooled reactor

This paper presents an evaluation of gaseous sulphur 35 behaviour in a typical Gas Cooled Reactor for a period of about 18 months. It briefly summarises the measurements of sulphur 35 in coolant for this period and then compares them with the results obtained from a calculational model. From this comparison, it is found that the predictions are generally lower than the experimentally determined levels by a factor of approximately 2. The Paper also includes an estimate of the maximum reactor coolant level of sulphur 35 which is likely to arise, based on the same calculational model and including the identified systematic factor. The result is a level of 8mCi/te. Finally, using the existing relationship between the level of sulphur discharged to the environment and that in the reactor, the maximum environmental discharge corresponding to the peak coolant level has been assessed to be 1200 mCi per month. (author)