FINAL CALANDRIA TUBE INSERT REMOVED FROM DARLINGTON NUCLEAR’S UNIT 2

​The final calandria tube insert (CTI) was removed on March 28, completing yet another step in the disassembly phase of Darlington Nuclear Generating Station’s Unit 2 reactor.
Wednesday, March 28, 2018

​The final calandria tube insert (CTI) was removed on March 28, completing yet another step in the disassembly phase of Darlington Nuclear Generating Station’s Unit 2 reactor.

A new production planning tool used during CTI removal is credited for building efficiency and allowing for early completion of this important work series in the Darlington Refurbishment project.

We developed a process map showing the work step-by-step, including all processes involved,” said Perrik Le Dreff of the Darlington Refurbishment team.

The process included durations for each step, down to the second, for: reactor component removal; placement of the removed items into protective flasks; transport to the Re-tube Waste Processing Building; storage preparation and placement into waste containers; and the flasks’ return trip to Unit 2.

“The result was like clockwork since we understood every discrete step of the sequence including the impact of speeding up or slowing down one step and the impact on the rest of the steps,” said Le Dreff.

These maps are now being used in subsequent work series. 

Calandria tubes sit in the reactor’s core, each housing a pressure tube containing nuclear fuel bundles. They are secured at each end by CTIs, a metal ring which forms a mechanical seal.

That seal was broken using induction heating during the last work series, allowing the inserts to be removed.

Completion of CTI removal sets the stage for extraction of the calandria tubes themselves, another step in dismantling the reactor. After this work series, the reactor will undergo inspection before the work of rebuilding Unit 2 begins.

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