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Problem-Driven Innovation

Problem-Driven Innovation

Developing Alternative Technology to Imp...

Valve Repair Takes Center Stage in Houston

Valve Repair Takes Center Stage in Houston

Attendees gathered June 2-3 in Houston t...

What Internal Best Practices Can Do for Valve Selection

What Internal Best Practices Can Do for Valve Selection

As time goes by, technology moves forwar...

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Problem-Driven Innovation

Problem-Driven Innovation

Monday, 20 June 2016  |  Mark A. Lobo, P.E.

Developing Alternative Technology to Improve Product Performance

Industrial product engineering teaches us to understand the difference between problem...

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Industry Headlines

Curtiss-Wright Awarded Contracts for U.S. Naval Defense Platforms

1 DAY AGO

Curtiss-Wright announced that it has been awarded contracts valued in excess of $80 million to provide valves for the U.S. Navy’s Virginia-class submarines and Ford-class aircraft carriers. The awards were received from Bechtel Plant Machinery, Inc. and General Dynamics Electric Boat Division ...

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DeZURIK Adds Dedicated Clean Room to Sartell Plant

3 DAYS AGO

In order to ensure proper cleaning procedures are performed on valves intended for oxygen, ozone, chlorine, hydrogen peroxide, isocyanate and other applications, DeZURIK has constructed a new dedicated clean room within its Sartell, MN manufacturing plant.

Operated by trained cleaning technicians, DeZU...

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Global Upstream Spending Slashed by $1 Trillion

1 DAY AGO

Global upstream development spending from 2015 to 2020 has been cut by 22% or $740 billion since the oil price started to drop two years ago, according Wood Mackenzie's research . When you include cuts to conventional exploration investment, the figure increases to just over $1 trillion. Expect to see...

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EPA Bans Fracking Wastewater Disposal at Public Treatment Plants

3 DAYS AGO

The EPA has finalized a rule establishing pretreatment standards for discharges of wastewater from onshore unconventional oil and gas (UOG) extraction facilities to municipal sewage treatment plants (also known as publicly owned treatment works, or POTWs). The rule is designed to prevent the discharge...

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U..S. Durable Goods Orders Down 2.2% in May

17 HOURS AGO

New orders for manufactured durable goods in May decreased $5.3 billion or 2.2% to $230.7 billion, the Commerce Department announced today. This decrease , down following two consecutive monthly increases, followed a 3.3% April increase. Excluding transportation, new orders decreased 0.3%. Excluding d...

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Federal Judge Halts New BLM Fracking Rules

1 DAY AGO

“The Obama administration will fight a federal judge’s ruling overturning its effort to regulate hydraulic fracturing on public lands,” Bloomberg reports . The White House says they will take the case to the U.S. Court of Appeals.

“The ruling, issued late Tuesday by Wyoming-based...

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Actuation in Nuclear Power Plants

vmfall11_nuclear_h

The thousands of actuators used in a nuclear plant face some pretty tough conditions as well as rigorous testing.

Currently, 104 nuclear power-plant reactors are working in the United States, and all of them have operating environments that are extremely challenging. Of those 104 plants, 35 are classified as boiling and 69 as pressurized water reactors.

While the design details vary from plant to plant, each nuclear facility has thousands of valve actuators used in various processes and applications. The newest-generation nuclear plant has more than 13,000 valves.

It’s clear, then, that valve actuators play vital roles in maintaining process safety, efficiency and productivity in a wide range of situations.

This article contains a brief description of some of the special circumstances encountered in challenging nuclear environments and the different styles of actuators used to meet demanding operational and safety requirements.

STRICT GUIDELINES AND REQUIREMENTS

vmfall11_nuclear_electric_actuatorWith O-ring sealed covers in place on this electric actuator, the motor, limit and torque switches, as well as other electrical components, are housed within a pressure-tight enclosure. This keeps out dirt and moisture and prevents breathing from expansion and contraction of the internal air caused by temperature changes.All equipment used in nuclear plants built in the United States is certified under stringent guidelines mandated by the Nuclear Regulatory Commission (NRC). Verification of reactors or equipment to standards from other countries is not acceptable for the 104 working reactors in the U.S.

To understand basic requirements the nuclear power industry faces in this nation, a review of the similarities and differences between nuclear power and fossil power is helpful.

In a fossil power plant, coal might be crushed and mixed with air to boil water, which produces steam to drive a turbine. With nuclear reactions, the process is different, but the operational objective is essentially the same—to heat water to produce steam to drive a turbine. With a coal steam generator, the activity of burning the pulverized coal and producing steam is contained within what is termed the “boiler island.” Because of the strong similarity to what happens in the coal plant, many engineers and technicians in a nuclear plant refer to the area where steam generation occurs as the “nuclear island.”

vmfall11_nuclear_cutawayThis cutaway illustration shows the internal components of a typical electric actuator.Within the nuclear reactor, equipment must meet rigorous standards. Since radiation is very high, the standards require all equipment materials used in this phase of the process to withstand high levels of radiation for the life of the plant. Therefore, materials such as iron or steel are required rather than aluminum. Also, temperatures in this portion of the plant are elevated, which will affect seal materials. The combination of severe environmental conditions determines the various coatings and paints allowed for use in this area, which is known as “inside containment.”

To be suitable for service in a nuclear reactor, an actuator must go through specific testing by outside testing agencies. The test reports produced must then be reviewed not only by the actuator suppliers, but by consulting engineers and the utilities themselves. Many documents also are reviewed by the NRC.

The tests for actuators used “inside containment” apply to all styles. The plants use electric motor operators as well as pneumatic cylinder actuators and hydraulic cylinder actuators. All of these actuators must be tested to ensure they can withstand the environment for their expected lives. Also, in addition to environmental concerns, the actuators must be able to operate during extreme accident conditions such as an earthquake.

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