Abstract
Summary：Much of recent trouble is generated at the gray zone, which is not a clear dangerous domain, and can be either dangerous or safety by the condition. In the gray zone, there are often inconsistencies between the ingenuity for efficiency by field engineers and workers, and the rules for the safety and high reliability by design engineers, and it often develops in trouble. This paper would like to consider what kind of communication is expected by the whole organization, and what kind of cooperative relationship it's necessary to build to secure safety and the high reliability in a systems operation.
