Atomic Energy of Canada Ltd says that 46% of the repair activities on the NRU reactor vessel have been completed and puts the earliest return-to-service date at the end of April. However, “technical challenges with the repair sequence continue to pose risk of schedule slippage,” according to AECL’s latest update on 3 March.
In the update AECL said that the repair team had just completed a horizontal weld repair and was finalizing preparations for the application of a horizontal weld build-up applied over two backing strips.
Preparations continue for the final repair sequence, which will be the most complex stage of the repair. It will involve the installation of plates welded to the vessel wall combined with the application of horizontal weld build-up.
As with all repair activities to date, welders continue intensive practice sessions using the NRU mock-up, which was installed in November. Given the complexity and challenging nature of these repairs, an additional level of preparation in programming the semi-automatic welding sequences is required along with the qualification of welders.
The NRU reactor, a major source of radioisotopes, has been shut down since May 2009 when a heavy water leak was detected.
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