Severe Service Hydraulic Actuators for the Nuclear Power Industry

Enertech Nuclear Qualified Electro-Hydraulic Actuators

Enertech, formerly Paul Munroe Hydraulics, Inc., has provided engineered solutions to the nuclear power industry since 1967. Our expertise in fluid power led to the development of a fast acting, compact hydraulic actuator to meet the demanding requirements for safe plant shut down and post-accident cycling of critical nuclear valves and dampers. For over 30 years, Enertech has supplied actuators qualified to stringent IEEE standards. Today, we have actuators in more than 500 nuclear installations, both inside and outside containment.

DesignYears of experience and development led to our second generation electro-hydraulic operator (EHO); a fully self-contained actuator for linear or rotary applications. The IEEE qualified design provides increased reliability and performance. The Enertech EHO utilizes an electric motor and hydraulic pump qualified for post design basis event cycling following restoration of Class 1E power, as well as an integral gas accumulator for motive force without AC power.

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Engineered Solutions for the Nuclear Power Industry

Environmental Qualification and Quality AssuranceEnertech EHOs are used in nuclear safety-related and non-safety applications around the world. EHOs have been successfully tested and qualified to IEEE 382, Case IV for inside containment design basis radiation, pressure and temperature for safe plant shut down use. Seismic, vibration, and chemical spray conditions have also been successfully met in accordance with IEEE 344 and 323 standards.

All EHOs are manufactured under Enertech’s Quality Assurance Program which complies with 10CFR50 Appendix B and NQA-1. Other nuclear quality standards for non ASME governed plants may be specified.

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Theory of OperationThe operating principle of Enertech’s EHO is founded on simple, basic, physical principles. A motor driven hydraulic pump forces pressurized hydraulic fluid into an accumulator permanently charged with nitrogen. The hydraulic fluid compresses the nitrogen which becomes a “gas spring.” This stored energy provides the motive force to operate the actuator. Directional control valves are used to select the direction of operation for both normal and accident conditions.

The modulating circuit operates in much the same way but utilizes a servo controller and a 1E qualified position feedback device to position the actuator in response to a proportional command signal.

Electro-Hydraulic Electric MotorPneumatic

Why Enertech EHOs for Isolation and Throttling Applications?

X

X

X

Integral, post-accident cycling

Failsafe w/o Class 1E power

Fast-acting (< 5 seconds)

XNo air supply required

XNo bulky spring packs required

X

X

Highest thrust/torque to weight ratio

Less than 1% positioning error

Features:Dual control trains: provides full redundancy

Self contained: stored energy; no air or Class 1E power required

Prolonged station blackout coping: Accumulators provide up to 72 hours of cycling with total loss of AC power

Fast-acting: ANSI Class 900, 42” gate valve design basis event closure in less than 5.0 seconds

Less than 1% modulating error: precise control valve positioning

“Trip proof” exercise circuit: periodic testing of valve operability without risk of inadvertent closure due to limit switch failure

Dual lock, anti-drift design: prevents position drift

Two-speed, anti-slam damping option: mitigates water hammer in fast closing, fluid applications

Manual hand pump: manual override for cycling that can be located at the actuator or up to 250’ away

cylinderrotator

or

to close

to open

speedcontrolpower unit

accumulator

directionalvalves

Enertech’s advanced EHO technology offers a flexible platform making it suitable for fast closing, high thrust applications like main steam isolation, or where responsiveness and accuracy are critical for throttling control of main feedwater or atmospheric steam dump valves. This proven design minimizes component complexity, reducing your cost of ownership.

Closed Loop Control:Enertech provides an exclusive 1E qualified modulating electro-hydraulic actuator. A direct mounted, qualified potentiometer provides immediate feedback for precise actuator/valve positioning in response to the control signal.

X

X

X

X

X

Actuator type

Design

Output (thrust)

Stroke

Speed

Failsafe positions

Qualified Life

*Custom strokes and thrusts available

electro-hydraulic, gas/hydraulic

linear (two-position or modulating)

up 525,000 lbs-f (238,136 Kgf)

up to 34 inches (863.6 mm)

up to 10 inches/sec (254 mm/sec)

fail close, fail open, fail in-place

60 years

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Linear Actuators for Isolation and Control

Linear Actuators for IsolationEnertech’s IEEE qualified EHO is the preferred technology for large, fast-acting isolation valves. The compact, self-contained design provides a high thrust-to-weight ratio that delivers adequate margin to close MSIV’s up to 42 inches, at design basis conditions, in less than five seconds. Enertech’s EHO utilizes internally ported manifolds, preventing tubing leaks and ensuring sustained isolation with no drift. Accumulators provide additional capacity to maintain extended isolation against maximum differential pressure.

Linear Actuators for ControlFor critical control functionality with stored energy capability and prolonged station blackout coping, Enertech’s EHO meets these requirements in one package. The modulating actuator uses an oil over oil design for precise positioning. Internal isolation valves prevent leakage maintaining actuator position without “hunting.” Control circuitry can be mounted up to 250’ away from the actuator in mild environments. Optional accumulators provide failsafe operation or additional capacity for control in the event of power failure.

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Application Highlight: Power Operated Atmospheric Steam Dump Valve A Midwestern utility undergoing an extended power uprate, wanted to increase their prolonged Station Blackout (SBO) coping time to 72 hours. As such, Power Operated Atmospheric Steam Dump Valves (POADVs) would require the ability to cycle for this period of time. The POADVs are critical for the plants cool down period as they regulate the relief of steam pressure and temperature. The ability to modulate the atmospheric steam dump valves without power is critical to safely bringing the plant offline.

The plant previously used pneumatic actuators, which are common for this application. However, the additional air capacity required for the prolonged SBO coping period proved unrealistic. The site did not have the space required for the additional air accumulators, and was concerned about the network of tubing required to supply the remote actuators.

Enertech proposed an oil over oil hydraulic actuator that would provide accurate and precise positioning for this critical modulating application. In addition, the required stored energy could be provided with only four accumulators mounted on the remote hydraulic power unit. This greatly reduced the space required to support the prolonged SBO mission.

Enertech’s EHO uses compressed nitrogen to maintain system pressure and operate the actuator for up to 72 hours. Actuator control is provided by low consumption DC solenoid valves, powered by the site’s backup batteries.

In response to lessons learned and enhanced safety requirements, this actuator design is being specified in hardened vent applications to safely control the release of hydrogen gas before concentrations reach dangerous levels.

Basic Specifications

Valve Valve

CG

13.5’

10.5’

CG

12,000 lbs.

19,000 lbs.

Enertech’s self-contained, compact, MSIV actuator compared to competitor’s equivalent actuator.

Typical Applications

Main Steam Isolation Valves

Feedwater Isolation Valves

MSIV Bypass Valves

Safety Injection System Valves

Atmospheric Steam Dump Valves

Feedwater Flow Control Valves

Recirculation Flow Control Valves

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Rotary Actuators for Isolation and Control

Rotary Actuators for IsolationFor critical rotary isolation valves, Enertech’s IEEE qualified EHO provides unmatched performance and reliability in a compact actuator. The self-contained design provides a high torque-to-weight ratio and delivers constant force throughout the actuator’s stroke. Sustained isolation is accomplished with accumulators for additional capacity to maintain extended isolation against maximum differential pressure.

Rotary Actuators for ControlEnertech’s IEEE qualified rotary modulating EHO is ideal for quarter-turn control valve applications like butterfly and ball valves. Positive positioning along the 90° stroke is maintained through the incompressible hydraulic fluid which prevents drift. These actuators modulate dampers controlling ventilation to critical areas of the plant, including the control room. Rotary modulating EHOs are also used for containment vent applications to prevent the buildup of hydrogen gas during a design basis event. An integral accumulator cycles the actuator in the event of power failure or loss of control signal, or to provide failsafe operation.

Application Highlight: Damper ControlSeveral utilities have EHOs installed in HVAC applications on dampers used for control room and Aux building ventilation and isolation. For these applications, our smallest EHOs are compact, self-contained actuators which precisely position volume control dampers, while providing fast isolation for fire and other safety dampers.

When dampers are located in difficult to access locations or multiple actuators are required, our EHOs can be configured with a separate, remote, hydraulic power unit (HPU) to simplify installation and reduce the plants cost of ownership. Depending upon the size, up to eight actuators can be operated from a single HPU.

These compact EHOs are ideal for dampers and small quarter-turn ball, butterfly and plug valves. In applications where critical post accident cycling is required, our EHOs easily achieve 72 hour SBO survivability.

Engineered Solutions

2

1

0

5

6

4

3

200

100

400

300

600

500

25 20 15 10 5 0

Controlled closure speed

Stem tension pipe break

Stem tension spurious closure

MS

IV c

losi

ng s

pee

d (i

ps)

Ste

m t

ensi

on

forc

e (0

00 lb

s)

EHO stem position (in)MSIVOpen

MSIVClosed

a LOCA-induced pipe break. The actuator must transition instantly to a damper when sensing load.

The increased load requirements made an air actuator prohibitive due to size and weight. Enertech’s EHO is a compact solution which provides 120,000 lb-f motive force with self contained nitrogen gas for normal operation or spurious closing. For pipe break reverse flow conditions, the actuator generates a 350,000 lb resistive load to slow the disc velocity, protecting the valve internals and maintaining MSIV integrity.

In less than 30 weeks, Enertech designed, manufactured and delivered an actuator for the site’s fall outage which met the increased performance requirements to support the extended power uprate.

To demonstrate the actuators ability to initiate motion and then control valve closing speed, the pipe break was simulated using a bank of 5,000 psig nitrogen bottles driving a slave hydraulic cylinder as shown in the photo below.

EHO Control of Load on Main Steam Isolation Check Valve

Enertech’s EHO design is fully customizable to meet the needs of your unique and specific application requirements. A staff of Professional Engineers can evaluate and design a solution to meet your performance, seismic and environmental requirements.

Application Highlight:Main Steam Isolation Check ValveWhile undergoing an extended power uprate, a Southeaster utility realized that the air actuator on their main steam isolation check valve (MSIV) was not adequate for the increased flow rate. With higher reverse flows the stem to disc connection and connection pin have the potential to break and compromise the safety function of the MSIV.

The actuator on a swing check style MSIV serves a dual purpose. The actuator can be used to provide thrust to open and close the valve; it can also protect the valve seat and internals by acting as a damperto limit disc velocity and prevent slamming during

Basic Specifications

Actuator type

Design

Output (torque)

Speed

Failsafe positions

Qualified Life

*Custom torques available

electro-hydraulic, gas/hydraulic

rotary (two-position or modulating)

up 300,000 in-lbs (33,895 Nm)

less than 1.0 seconds for 90°

fail close, fail open, fail in-place

60 years

Typical Applications

Volume Control Dampers

Containment Vent Valves

Containment Air Isolation Valves

Recirculation Air System Valves

Containment On Line Air System Valves

Containment Purge System Valves

Hardened Vent

First in Customer Service to the Global Nuclear Power IndustryEnertech, a business unit of Curtiss-Wright Flow Control Company, is an engineering, manufacturing,

distribution and service company committed to providing solutions to meet the unique requirements of the

nuclear power industry. Enertech provides integrated system solutions that include advanced valves, actuators,

pumps, instrumentation, snubbers, engineered filtration and heating systems, diagnostic and test equipment,

qualification and dedication services, outage support services and equipment repair and field service. Whether

it’s solving chronic component related problems, obsolescence challenges, maintaining and upgrading installed

equipment, assisting with power uprates and plant life extensions or supporting new reactor construction, we

have solutions to maximize performance.

Brea, California 2950 Birch Street Brea, CA 92821 enertech@curtisswright.com http://enertech.cwfc.com 714.528.2301

BR - 1305 - 8.2012R1 - ET

Enertech provides EHOs that are form, fit and function replacements for obsolete actuators found in many Generation II nuclear plants. Enertech’s gas spring design eliminates complex air pilot control sub loops found in competitors’ older electro-hydraulic actuator designs. Commercially available sub-components and services assure uninterrupted aftermarket support for the life of your plant.

Enertech

2950 Birch Street Brea, CA 92821

enertech@curtisswright.com

714.528.2301

GUJU Technology, Inc.

#1808 Jeongja I-Park, 100 Baekhyeon-ro,

Bundang-gu, Sungnam-si, Gyeonggi-do, Korea

82.31.704.0091

Curtiss Wright (Tianjin) Flow Control Co., Ltd.

No. 3 Quanhui Road, Wuqing

Development Area, Tianjin China 301700

86.22.8216.6100

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