03232017Thu
Last updateWed, 22 Mar 2017 3pm

i

Valve Selection in Pulp and Paper Operations

Valve Selection in Pulp and Paper Operations

Over the centuries, the pulp and paper i...

How to Improve Control Valve Performance with Positioners

How to Improve Control Valve Performance with Positioners

As the final control element in most pro...

VMA Technical Event: Engineering Valves in the Extreme

VMA Technical Event: Engineering Valves in the Extreme

While much the 2017 VMA Technical Semina...

FEL: The Preferred Phase for Valve Technical Definition

FEL: The Preferred Phase for Valve Technical Definition

A typical oil and gas capital project cy...

The Weekly Report

New Products

  • ja-news-2
  • ja-news-3

Industry Headlines

Metso Launches Digital Program to Accelerate Growth

Wednesday, 22 March 2017  |  Chris Guy

Metso has set up a Digital Program to accelerate the company’s digital capabilities, which are required to succeed in the future of minerals pro...

Readmore

Loading...

Industry Headlines

Metso Launches Digital Program to Accelerate Growth

13 HOURS AGO

Metso has set up a Digital Program to accelerate the company’s digital capabilities, which are required to succeed in the future of minerals processing and flow control. Metso's ambition is to become one of the digital leaders in the industries it serves. This means for example turning custome...

Readmore

Emerson Forms Alliance with TopNIR Systems

13 HOURS AGO

Emerson Automation Solutions and TopNIR Systems have joined forces to create the industry's first complete solution for optimizing crude blending operations to exploit the profitability opportunity of a wide array of different crudes by providing hydrocarbon property data in real-time that helps ident...

Readmore

U.S. Crude Oil Production Decreased in 2016

15 HOURS AGO

Even with a rising crude oil price throughout most of 2016, total U.S. oil production in 2016 was below its 2015 level. However, the U.S. Energy Information Administration reports , monthly production began growing in the fourth quarter of the year after declining over its first three quarters. Total ...

Readmore

CO2 Emissions Flat for Third Straight Year

1 DAY AGO

Global energy-related carbon dioxide emissions were flat for a third straight year in 2016 even as the global economy grew, according to the International Energy Agency , signaling a continuing decoupling of emissions and economic activity. This was the result of growing renewable power generation, sw...

Readmore

Consumer Sentiment Reaches Highest Level Since 2000

2 DAYS AGO

The overall level of consumer sentiment remained quite favorable in early March due to renewed strength in current economic conditions as well as the extraordinary influence of partisanship on economic prospects. The current economic conditions component reached its highest level since 2000, largely...

Readmore

U.S. Manufacturing Output Rose 0.5% in February

2 DAYS AGO

Industrial production was unchanged in February following a 0.1% decrease in January. In February, manufacturing output moved up 0.5% for its sixth consecutive monthly increase . Led by advances of more than 1% for nonmetallic mineral products, fabricated metal products, and machinery, the production ...

Readmore

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.

  • Latest Post

  • Popular

  • Links

  • Events

Advertisement

Looking for a career in the Valve Industry?

ValveCareers Horiz

To learn more, watch the videos below or visit ValveCareers.com a special initiative of the Valve Manufacturers Association