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Valve Basics Training Helps Fill Industry Skills Gap

Valve Basics Training Helps Fill Industry Skills Gap

One of the most keenly felt needs in tod...

An End-User’s Perspective on Valve Selection and Risk

An End-User’s Perspective on Valve Selection and Risk

I am not a valve expert, although I ofte...

New Test Stamp and More Updates on Pressure Vessel Codes

New Test Stamp and More Updates on Pressure Vessel Codes

A new test organization program and stam...

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Chemours Selects Wilmington, DE for its Global Headquarters

5 HOURS AGO

The Chemours Company will locate its global headquarters in Wilmington, DE. Chemours began evaluating headquarters location options more than 6 months ago with Delaware, New Jersey and Pennsylvania all under active consideration. Recent changes to Delaware’s corporate tax structure were key comp...

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ValvTechnologies Successfully Completes NUPIC Audit

6 DAYS AGO

ValvTechnologies, Inc. recently achieved NUPIC-approved suppliers list status, upon successful completion of the Nuclear Procurement Issues Committee (NUPIC) audit conducted at the Houston facility. NUPIC members include all domestic U.S. nuclear utilities as well as several international members.

Form...

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Feds Warn of Bolt Failures in Offshore Drilling

48 MINS AGO

On Monday, Bureau of Safety and Environmental Enforcement (BSEE) director Brian Salerno held a press conference aimed at oil & gas regulators. The issue he wanted to draw attention to is the failure of bolts in offshore drilling equipment such as blowout preventers. This problem, Salerno says, has...

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Monthly Renewable Electricity Generation Surpasses Previous Years

3 HOURS AGO

Renewable electricity generation has surpassed levels from previous years in every month so far this year, according to the U.S. Energy Information Administration ( EIA ). Both hydroelectric and non-hydroelectric renewables have contributed to this trend, but in different ways. On the West Coast, hydr...

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Advanced Manufacturing Outpaces Rest of Production Sector

6 HOURS AGO

A new report from the Brookings Institution finds that high-tech advanced manufacturing bucked both global economic challenges and the longstanding shrinking of the traditional manufacturing sector over the last two years. While job losses were felt in other pockets of the production sector, advance...

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Texas Manufacturing Activity Increased in August

7 HOURS AGO

Texas factory activity increased in August, according to business executives responding to the Texas Manufacturing Outlook Survey . The production index, a key measure of state manufacturing conditions, came in at 4.5 after a near-zero reading in July, suggesting output picked up this month.

Other meas...

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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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