Abstract: A mold suitable for continuous metal casting comprising a cavity opened at both ends, in which a vertical cross sectional shape at the inner wall surface of the cavity from a meniscus position to a required region is formed as a restriction portion corresponding to the amount of shrinkage of a charged material from a liquid phase to a solid phase. This can prevent internal cracks at the corners of a cast product formed in the chilled layer. Then, a mold for use in continuous metal casting capable of coping with increasing casting rate is provided.

Abstract: The present invention provides an underground-environment simulator which simulates underground environment spaces used for radioactive waste disposal or the like, and has a hermetic box, wherein the carbon dioxide gas concentration inside the box can be adjusted to an optional level, and the atmosphere inside the box can be uniformly and stably maintained. In the underground-environment simulator of the present invention, a carbon dioxide gas feeding means feeds carbon dioxide gas into a circulating gas circulation which controls the atmosphere inside the hermetic box, and the concentration of carbon dioxide gas in the circulating gas is measured and adjusted to a predetermined level while oxygen is removed from the circulating gas in an oxyhydrogen reactor. Accordingly, the carbon dioxide gas concentration can be controlled within a low concentration range, and various underground environments can be accurately simulated by varying the carbon dioxide gas concentration to an optional level.