France’s Framatome said on 11 May that it had recently signed two contracts to upgrade systems and equipment used to manage operations at the Krško NPP in Slovenia. The company will design, deliver and install new instrumentation and control (I&C) systems and replace the thimble tubes, which are an important part of the plant’s in-core neutron flux measurement system.

“For our work with the Krško Nuclear Power Plant, our team brings a unique focus on our customer’s need to modernise the plant and extensive engineering capabilities in various I&C systems and reactor designs,” said Frédéric Lelièvre, senior executive vice president, Sales, Regional Platforms and the I&C Business Unit at Framatome. 

Framatome’s team will replace the plant’s existing I&C system that is part of the anticipated transient without scram mitigation system actuation circuitry (AMSAC) cabinets. The AMSAC system provides backup to the primary protection system responsible for tripping the turbine and initiating auxiliary feedwater flow. It was developed to prevent excessive reactor coolant system pressure after an anticipated transient without scram event.

Framatome will also design, supply and replace 36 thimble tubes, including thimble tubes with a new nitriding surface hardening process designed for increased longevity, and complete a study on tube wear behaviour. The company will complete these upgrades during the plant's outage in autumn 2022.

The single unit Krsko NPP, operated by Nuklerana elektrarna, is located in Slovenia near the border with Croatia, and generates some 40% of Slovenia's electricity output. Its two-loop 688MWe Westinghouse pressurised water reactor began commercial operation in January 1983.