[en] Motor Operated Valves (MOV) are in many plant systems safety-related part of equipment. From their proper function depends response of a safety system and its essential function. Their proper maintenance and testing is an important part of every nuclear power plant surveillance and testing programs

[en] With the rising cost of operating and maintaining a nuclear power it is necessary to identify areas where applying available resources will curb these costs. This paper describes how O and M cost can be decreased through an effective valve maintenance program which provides the flexibility of adjustment of maintenance activities based on experience. Also, properly trained personnel are heart of a safe and reliable plant maintenance and operation. Therefore, an investment in a comprehensive training and evaluation program will yield a handsome return. NMAC guides are oriented to provide technical description on equipment along with maintenance recommendations. These can easily be adapted as reference material by the training departments

[en] A new valve blowdown test facility is completing commissioning at the Marchwood Engineering Laboratories of Britain's Central Electricity Generating Board. BRAVO, as the facility is known, will prove the performance of the safety and relief valves to be used in Sizewell B, Britain's first PWR. (author)

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[en] There are thousands of valves in a nuclear power plant (NPP) used for control, safety and checks in various plant systems, so there is a well-identified need for fast and reliable inspection and diagnostics of valves. Digital radiography can provide considerable improvements to the inspection and testing procedures for valves in comparison to classical film radiography. These improvements can lead to significant financial advantages by providing real-time inspection results, significantly reduced inspection and decision-making time, and reduced operational cost. Digital image processing, including digital image enhancement, digital archiving, and digital communication of the images and the results, is also a considerable advantage over classical film radiography technology. Another advantage of digital radiography technology is the improved safety and the reduced environmental impact due to reduced exposure/test times, use of smaller exclusion zones, elimination of chemical processing, and absence of disposable materials. This paper reviews the existing technology and evaluates the potential of digital radiography for inspection and diagnostics of valves. Station needs and requirements are assessed, and the safety, environmental and economical constraints of digital radiography techniques estimated. The advantages and disadvantages of different digital radiography equipment are compared, and their limitations and characteristics studied. (author)

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[en] This standard practice covers full ported cast iron gate valves with flanged or threaded ends. These valves are suitable for general purpose use

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[en] This valve includes, inside a tube, a valve seat having a hole that can be obturated by a ball placed on the fluid arrival side and means to apply the ball against the valve seat. It also includes a rod passing through this opening and a thermal system enabling the rod to be actuated so that it pushes the ball in the direction only of the fluid arrival to allow it to pass through this opening. Application to the use of valves in a nuclear environment or in an aggresive medium