A system for cooling a high pressure section of a turbomachine includes a conduit configured to carry cooling steam from a boiler to a space upstream of a first stage nozzle of the turbomachine. The conduit extends through a housing of the turbomachine and a nozzle diaphragm of the first stage nozzle. The system further includes a control valve in the conduit configured to regulate the flow of cooling steam. A turbomachine includes a housing; a turbine shaft rotatably supported in the housing; and a plurality of turbine stages located along the turbine shaft and contained within the housing. Each turbine stage includes a diaphragm attached to the housing. The diaphragm comprises a plurality of nozzles. A hole is provided in the diaphragm upstream of a first stage of the plurality of stages for the introduction of cooling steam. A method of cooling a high pressure section of a turbomachine includes introducing cooling steam into the turbomachine through the at least one hole.