Radioactivity:

Radioactivity of the reactor coolant system is controlled and monitored since it is a good indicator of various conditions which might occur in the system. These involve increased corrosion, crud bursts, fuel component defect or failure, or improper operation of the ion exchanger (whereas installed). There levels in the reactor coolant system are generally kept at nominal values in during general conditions through the ion exchanger.  Within facilities that do not use ion exchangers, another methods which vary from facility to facility are used to control radioactivity.  These involve processes like as chemical cleanup followed through feed and bleed along with following disposal process and reactor shutdown in severe cases.  Reactor coolant gaseous activity is also monitored, and it gives an indication of cladding failures and the introduction of air during reactor operation. Gaseous activity levels are generally controlled through degassification.  Operating limits are built in most reactor facilities to operate the reactor safely, to limit radioactive releases to the environment, and to avoid excessive personnel exposure in during shutdown and operation.