The reasons for control of selected chemistry parameters, and some of the more common methods of controlling these parameters will be discussed. No attempt will be made to identify specific values of any of the parameters discussed because of the number of different reactor facilities involved, but an overview concerning the bases and common methods used will be included. For operating values and specifications, users should refer to local facility publications. In addition, some information on tritium is provided.

EO 1.5STATE the following for reactor water chemistry.

a. Nine parameters controlled

b. Reason for controlling each parameter

c. Method of controlling each parameter

EO 1.6STATE the possible effects of abnormal chemistry on core conditions.

Specific Parameters

Specific chemical parameters vary from facility to facility but generally include the following: pH, dissolved oxygen, hydrogen, total gas content, conductivity, chlorides, fluorine, boron, and radioactivity. For the parameters indicated, control is generally achieved by one or more of three basic processes.

(1) Ion exchange in the primary system demineralizer(s) or by supplemental chemical additions

(2) Oxygen scavenging by hydrogen or hydrazine addition

(3) Degassification

Table I lists the more common chemistry parameters measured and/or controlled, the reasons each is measured and/or controlled, and control methods utilized.