To minimize occurrence of damage to pressurizer nozzles and the CRDM, basic management strategies consist of: operation within operating guide­lines; inspection and monitoring; assessment of any degradation that is detected; and maintenance. The main degradation mechanisms which can occur in pressurizer nozzles and the CRDM are thermal fatigue, vibratory fatigue, SCC and boric acid corrosion. Because coolant leakage through the heater sheath, instrument penetrations or manway cover gasket can cause corrosion and SCC of other equipment of the pressurizer system, this must be controlled. Molybdenum di-sulphide lubricant should also not be used in a steam exposed environment, because experience suggests that MoS2 has a pronounced tendency to decompose in the presence of high temperature and moisture conditions releasing sulphide which is a known promoter of SCC. In the United States, to manage ageing of vessel head penetrations and nozzles, the utilities are forced to conduct a regular inspection under ASME Code Case 694. Some plants also conduct supplementary inspections on the PWSCC sensitive zone. Many power plants conduct supplemented inspec­tion and replace their RPV heads with new ones (IAEA, 2007).