Minor design changes for controlling reactor inlet header temperatures in CANDU reactors

Most CANDU operators are dealing with increasing Reactor Inlet Header (RIH) Temperatures. Expensive Steam Generator (SG) tube cleaning campaigns have been executed on a number of units with varying degrees of success. Other operators have resorted to boiler pressure reductions, which in some cases is leading to unit deratings and lost production. Several minor design changes were evaluated as an alternative means for controlling RIH temperature. The general conclusion of the study is that in the right circumstances, minor design changes can provide a cost effective means of controlling RIH temperatures by avoiding or deferring repeated Inner Diameter (ID) SG tube cleanings and/or additional power deratings. (author)