05202018Sun
Last updateFri, 18 May 2018 4pm

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The Past, Present and Future of Fire Testing

The Past, Present and Future of Fire Testing

Because so many of the applications wher...

Advancements in Blue Laser Scanning

Advancements in Blue Laser Scanning

As the industrial world continues to exp...

Cavitation in Globe Valves—and Proposed Solutions

Cavitation in Globe Valves—and Proposed Solutions

Straight pattern globe valves are widely...

The VMA Knowledge Forum, Part Two: The Human Factor

The VMA Knowledge Forum, Part Two: The Human Factor

Finding and retaining the right talent i...

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Industry Headlines

Emerson Agrees to Buy Aventics

Friday, 18 May 2018  |  Chris Guy

Emerson has agreed on terms to acquire Aventics from Triton for a cash purchase price of $620 million. Aventics deals in smart pneumatics technologies...

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Industry Headlines

Emerson Agrees to Buy Aventics

1 DAY AGO

Emerson has agreed on terms to acquire Aventics from Triton for a cash purchase price of $620 million. Aventics deals in smart pneumatics technologies that power machine and factory automation applications. Aventics significantly expands Emerson’s reach in a growing $13 billion market.

With cen...

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Conval Names Brian White Refining & Chemical Industry Manager

2 DAYS AGO

Conval has appointed Brian E. White as refining & chemical industry manager serving the petrochemical industry in the Gulf states and elsewhere as opportunities and needs arise.

Based in Houston, White has over 20 years of experience selling instrumentation and capital equipment to the oil & ga...

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Outside of U.S., Natural Gas Outlook Diminishing

2 DAYS AGO

The mood in the natural gas industry, at least outside the U.S., is not as optimistic as it once was. According to the International Energy Agency (IEA), demand has slowed considerably for most of the period since 2011, from an average of 2.8% per year between 2000 and 2010, to 1.4% per year from 2011...

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ExxonMobil, BASF Form Gas Treating Alliance

3 DAYS AGO

ExxonMobil Catalysts and Licensing LLC and BASF Corporation have signed an alliance agreement to jointly develop new gas treating solvents and process technologies for use in natural gas processing and petroleum refining. Under this new agreement , BASF will market and license technologies developed f...

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Leading Economic Indicators Up 0.4% in April

1 DAY AGO

The Conference Board Leading Economic Index (LEI) for the U.S. increased 0.4% in April to 109.4, following a 0.4% increase in March, and a 0.7% increase in February.

April’s increase and continued uptrend in the U.S. LEI suggest solid growth should continue in the second half of 2018. How...

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U.S. Factory Output Rose in April

2 DAYS AGO

Industrial production rose 0.7% in April for its third consecutive monthly increase. The rates of change for industrial production for previous months were revised downward, on net; for the first quarter, output is now reported to have advanced 2.3% at an annual rate.

Manufacturing output moved up 0.5...

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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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