PURPOSE: To enable degree of deterioration of a metal material to be detected by comparing a characteristic value which is obtained by polarization measurement according to the electro-chemical reactivation method on a surface of a metal material with that of a polarization curve which is obtained for a metal material with the same composition previously.
CONSTITUTION: An EPR senor built-in container 4 is moved to a position to be inspected on a wall surface of a nuclear reactor by a crane 3 and is retained. Then, a degree of fragility which is generated by accompanying prescription is measured by the electro-chemical reactivation method, thus obtaining a corrosion-sensitive characteristic of a metal. Then, by comparing it with a characteristic value which is obtained for a metal with the same composition previously, a strength reduction characteristic of a metal is evaluated. Namely, at a middle period or later of aging, a reactivation peak current density is increased rapidly. On the other hand, a passivation current density rises along with increase of aging time at an initial period of aging, thus enabling a degree of deterioration at an initial and middle periods or later of aging to be evaluated.
ISHIKAWA YUICHI
HOSAKA NOBUYOSHI
