The cooling of nuclear reactors through use of constantly maintained liquid flows is critical. To attend to our customers in the nuclear sector, we have residual heat removal pumps, charging pumps, main and auxiliary reactor feedwater pumps, containment spray pumps, medium head safety injection pump, concrete volute cooling water pumps, screw pumps, rotary vane pumps, control valves and containment sampling isolation valves. All of these items are fully compliant with international certification standards (including ASME and RCC).

Our involvement in the nuclear power market began with the first ever industrial scale nuclear power plant and continues with nuclear pump and valve installations in over 65% of operational nuclear power plants worldwide.

ClydeUnion Pumps offers a comprehensive Class 1, Class 2 and Class 3 product range and can also provide a full conventional island product offering designed for the high reliability and availability requirements of a nuclear facility. Key to our success in both civil and naval nuclear power is our ability to acquire and maintain the high standards required to design and build nuclear coded pumps.

Three Coded Facilities

Our three coded facilities - Glasgow-UK, Annecy-France and Houston, TX-USA, are all qualified to ASME “N Stamp” and/or RCC-M and boast a long history of excellence.

Annecy, France

Annecy Plant, 39 Avenue du Pont de Tasset, ZAE de Meythet, BP 435 Annecy Cedex, 74020 France

Glasgow, United Kingdom

149 Newlands Road, Cathcart, Glasgow, G44 4EX, United Kingdom

Houston, Texas

8800 Westplain Drive, Houston, Texas, 77041, United States


The CUP-TWL is a unique solution for turbine driven safety related duties in nuclear power plants. Capable of being engineered to match a broad range of system requirements, it consumes less physical space than separate turbine/pump configurations. Functioning as a turbine driven auxiliary feed water pump in a pressurized water reactor system and as part of the reactor core isolation cooling system in a boiling water reactor, the CUP-TWL provides a reliable decay heat removal capability.

It can operate without external services, so it has the ability to run for extended periods under a loss of external and/or back-up power to a reactor site. The CUP-TWL is one of the few proven technologies that can currently meet the demanding requirements of a station black out scenario, offering both existing and new sites a solution to improve the safety and integrity of their plant.

ClydeUnion Pumps offers:

  • Dedicated nuclear design department
  • In-house seismic, environmental and operability qualification
  • Qualification tests under accidental conditions: thermal transients, debris and seismic tests
  • Commitment to quality
  • ASME ‘N’, ‘NPT’ and ‘NS’
  • 10CFR50 Appendix B Program
  • RCC-M
  • Large, innovative, in-house research and development facilities
  • Comprehensive in-house software and analytical capability


There are many benefits of installing a TWLTM Pump including:

Independent Power Operation:

Operates without requiring electrical power, eliminating dependence on station batteries or manual operation.

Simplified Maintenance and Compact Design:

Easier maintenance with a compact design, fewer components, and improved accessibility compared to traditional pump and turbine arrangements.

Proven Reliability and Safety:

Demonstrated reliability in operation, coupled with reduced fire risk due to the absence of oil requirement.

Efficient and Compact Pumping Solution:

Approximately half the size of traditional pump/turbine setups, meeting or exceeding existing pressurized water reactor (PWR) installation requirements.

Enhanced Performance and Durability:

Fewer parts and no drive couplings result in improved reliability, better performance, and easier maintenance. Designed to withstand seismic events.

Extended Coping Duration in Emergency Situations:

Designed to extend Station Blackout (SBO) coping duration beyond the capabilities of existing turbine-driven pump sets in nuclear power plants. Can operate and start-up under completely flooded conditions, eliminating specific failure modes identified in NUREG reports.


  • Water lubricated bearings ensure reliable operation without the need for oil systems.
  • Self-contained governor and controls require no external services
  • No potential leak paths as the shaft does not penetrate the casing and there are no mechanical seals between pumped fluid and the atmosphere
  • Rapid hot or cold start-up
  • No overshoot beyond running speed
  • Accommodates water slugs both at start-up and during normal operation with no detrimental impact to equipment
  • Compact design

The TWL™ has a single casing design with no shaft protrusions, enabling it to start and operate while fully submerged. Extensive testing at our Glasgow facility has shown that it will maintain safety performance and continue to operate with no adverse effects or detrimental changes to performance for a minimum of eight hours. During this time, the pump can be started and stopped, again with no detriment to its performance.

Nuclear Valves

Copes Vulcan valves have been engineered and manufactured for the nuclear industry for over forty years, proudly producing globe, gate, swing check, butterfly, ball and sampling valves for our nuclear customers. We provide technical solutions for a variety of nuclear applications including feedwater, steam dump, pressurizer spray, reactor coolant, sampling, service water, and safety injection valves.

The Copes-Vulcan manufacturing facility in Houston, TX holds 'N', 'NPT', and 'NR' certification and is certified by ASME to manufacture valves and components to the Boiler and Pressure Vesssel Code.

Copes-Vulcan valves are manufactured for boiling water reactors (BWR), heavy water reactors (CANDU) and pressurized water reactors (PWR), and are supplied to many countries including the United States, Canada, Mexico, South Korea, China, Japan, Switzerland, Brazil and many more.

Typical nuclear product applications include:

  • Feedwater (Start-up, Main)
  • Atmospheric Dump
  • Sampling
  • High Pressure Safety Injection
  • Reactor Coolant
  • Service Water (RHR)
  • 3-Way Diverting and Converting
  • Closed Cooling Water
  • Heater Drains


We also have a specialist team of field service technicians who provide technical support to our customers, and have been actively providing refurbishments and upgrades of existing equipment to help the utilities to reduce their maintenance costs and support power uprates.


Refurbishment of existing valve components and assemblies to extend the life of the OEM equipment.


Upgrade and modernization of original equipment, replacing threaded trim with quick change trim.


Configuration/material changes to resolve potential operational issues due to changes in operating temperatures, pressures or flow rates.

Nuclear Valves

Our product range has been developed in response to the specific needs of our nuclear customers and comprises a variety of globe valves for standard to severe duty valve applications. With one of the largest selections of control valve trims available in the nuclear market, Copes-Vulcan valve designs can meet our customers' demanding requirements and conditions.

Containment Sampling Isolation valves are custom designed for the nuclear industry providing FCI 70-2 Class V shutoff, with excellent performance in high differential pressure applications. The valve was designed, built and tested in accordance with ASME Boiler and Pressure Vessel Code Section III for Classes 1, 2 or 3. ANSI B16.34 valves are also available.

Also available are high performance, reliable butterfly, ball, gate and check valves designed and customized for the nuclear industry.


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