The authors present detailed measurements of the radiated power loss from the TCA Tokamak using a 16-channel radiation bolometer array. The plasma density has been varied over a wide range up to the high density disruption limit, at several magnetic fields and plasma currents. The fractional radiated power is a well correlated function of the average electron drift speed, and is independent of the toroidal magnetic field. The occurrence of disruptions does not appear to be simply correlated with the total fractional radiated power, but more with the radiated power fraction on axis. The injection of light impurities clearly illustrates that there is no simple universal 'law' which relates the disruption limit in TCA to the measurable radiated power loss. No evidence of any disruption 'precursor' has been seen in the bolometer data.