14.38. Equipment maintenance is a very important plant operations activity, but is generally given little attention in engineering texts. In fact, accommodation of maintenance requirements is a vital plant design re­quirement. Components, piping, wiring, and auxiliary equipment must be arranged in such a manner that routine maintenance and component re­placement can be carried out efficiently. The presence of a radiation field can be an important design consideration.

14.39. Maintenance is usually planned during scheduled refueling shut­downs. Unscheduled shutdowns are expensive, with the economic penalty generally based on the cost of replacement energy. Therefore, measures to assure trouble-free equipment performance are justified and should be accomplished during planned shutdowns. During such shutdowns, careful work scheduling is necessary to avoid excessive outage time. Radiation exposure limits to personnel and the need for protective clothing require attention.

14.40. During the late 1980s, the NRC increased its involvement in nuclear plant maintenance. As a result, EPRI formed the Nuclear Main­tenance Applications Center (NUMAC) to improve maintenance effec­tiveness by coordinating information and developing technical repair guides for specific equipment. Also, the Institute of Nuclear Power Operations (INPO) has developed standards for maintenance. It is recognized that there is an optimum maintenance effort as a result of the cost of failures balanced by the expenses of preventive maintenance. A goal is to devote about 70 percent effort to preventive maintenance and 30 percent effort to corrective maintenance.