Chemical control in SGHWR circuits

The choice of materials from which to construct a direct cycle nuclear reactor is limited by nuclear and engineering requirements and by the environment in which they are required to operate. Development of materials themselves are discussed in other papers presented at this symposium, whilst engineering requirements have been indicated elsewhere (ref. 1). This paper is concerned solely with the chemical control of reactor circuits. Although a number of fluid circuits which require such control exist in the Winfrith SGHWR, only two of the water circuits have been selected for discussion to illustrate how the present systems came to be adopted and how subsequent development work has led to substantial improvements which can now be incorporated with confidence in future reactors.