Electrochemical monitor

The present invention concerns monitoring of BWR and ATR reactors, and is suitable to measure a hydrogen concentration in primary coolants, corrosion potential and impedance of pipelines stably in a circumstance of high-pressure and high-temperature at 288degC. Namely, a monitor of a hydrogen ion concentration comprises (1) an insulative tubular casing allowing inflow of the high temperature and high pressure water flow in pipelines, (2) a reference electrode and a semiconductor electrode contained in the casing and disposed by way of a counter electrode. In this case, the semiconductor electrode is formed by diffusion-bonding copper as an electrode terminal, to an n-type semiconductor made of TiO2 or ZrO2 and insulation-coating the surface thereof except for the diffusion-bonded portion. The amount of corrosion of metals depends on the amount of generated hydrogen. According, the monitor of the present invention is disposed to a path in which the high temperature and high pressure water is circulated, for measuring the hydrogen ion concentration in the high temperature and high pressure water, thereby enabling to monitor corrosion and estimate the amount of hydrogen absorbed to metals. Further, corrosion rate of metals can be estimated based on the measured values for the corrosion potential and the impedance. (I.S.)