Abstract: The present invention relates to ceramics having excellent fusing damage resistivity against melt of metal or other inorganic materials. If a member formed of BN ceramics in the prior art comes into contact with melt of metal, glass or the like, the member would be readily fused and damaged at its contact portion. Hence, if AlN in the range of 1.ltoreq.AlN<50 weight % is added to BN ceramics containing 50 weight % or more of BN component, the fusing damage resistivity is greatly improved. Furthermore, Y.sub.2 O.sub.3 whose weight proportion relative to AlN content is 1.0-10.0%, is added, strength of the BN ceramics is greatly improved. A protective cap for a thermocouple formed of the ceramics according to the present invention is excellent in durability against molten metal, and so, continuous temperature measurement for molten metal is possible.

Abstract: A steam turbine power plant having a feedwater heater, a boiler, a steam turbine driven by steam generated in the boiler, and a condenser for condensing steam exhausted from the steam turbine. An extracting steam pipe is provided which includes a control valve for extracting a steam from the steam turbine to the feedwater heater, with a controller being provided for controlling an amount of the extracting steam in order to control a feedwater temperature flowing through the feedwater heater at an adequate range when the plant is starting or stopping. By controlling the feedwater temperature, a thermal stress generated in the feedwater heater is reduced to below an allowable value so that it is possible to increase the working or service life of the feedwater heater and improve the reliability of the steam turbine plant while reducing the maintenance costs thereof.

Abstract: A vacuum retaining arrangement for retaining a vacuum within a condenser of a steam power plant during a short term outage or shutdown. At least a portion of a turbine gland packing near the condenser, with respect to a sealing steam supply portion, is connected and communicated with an air extractor through a gland condenser. The sealing steam which would otherwise flow into the condenser from the turbine gland package is suctioned or extracted from the gland packing into the gland condenser and the air extractor during the short term outage or shutdown so as to prevent the sealing steam from leaking into the condenser.