compressible thermal sleeves

Safely Replacing Thermal Sleeves at the Sizewell B Plant in a Fraction of the Expected Time

September 14, 2021 by Westinghouse Electric Company

Westinghouse cements its position as the industry leader in thermal sleeve replacement

In late April 2021, the Sizewell B Nuclear Power Station located in Suffolk, England – the U.K.’s only Pressurized Water Reactor (PWR) – discovered an anomaly following the removal of the Reactor Pressure Vessel (RPV) head.

A thermal sleeve had become detached from the RPV head but remained in place on the upper internals.

"It was outstanding to see how Westinghouse and our team worked together on this milestone," Robert Gunn, Director of the Sizewell B Nuclear Power Station, said. "It strengthened our mutual trust and reinforced our very good relationship for future works."

Westinghouse quickly provided optioneering works to EDF (the plant’s owner and operator). We were subsequently awarded a contract for the removal of the 15 affected thermal sleeves and replacement with our Compressible Thermal Sleeves (CTSs).

Our team of experts stepped in, carefully removing the 15 old thermal sleeves and remnants utilizing an Electrical Discharge Machining (EDM) technology. The removed sleeves and RPV head were then inspected before installing the new CTSs.

With EDF’s support, the Westinghouse team successfully completed the CTS project at the Sizewell B plant in just two months – a fraction of the typical time frame (six to nine months).

We were able to achieve this milestone thanks to the efforts of our cross-functional, multi-location, multi-time zone teams who manufactured and installed the CTSs in a timely manner while maintaining the highest standards of safety and quality.

First identified as an issue in 2014, thermal sleeve wear has posed a challenge to the industry for many years.

Westinghouse’s CTS solution allows for a safe and rapid replacement of worn thermal sleeves that:

  • Doesn’t require any welding
  • Minimizes the impact during outages
  • Meets regulatory requirements
  • Ensures continued safe operation of power plants

“This is an important milestone that helped our customer save on outage time, while offering a cost-effective solution for replacing existing worn thermal sleeves,” said Johan Danielsson, Westinghouse’s EMEA Director, Outage and Maintenance Services. “

Compressible Thermal Sleeves have been designed to replace the existing thermal sleeve from under the reactor vessel head instead of the alternative approach which involves cutting into the canopies above the reactor vessel head, providing a low-impact, regulatory-compliant and safe solution for outage and maintenance works.