Pickering Unit 7 calandria tube leak operational impacts

In September 2005 Pickering Unit 7 developed a calandria tube leak. As a result the moderator experienced elevated levels of total inorganic carbon (TIC). While in the over-poisoned guaranteed state in April 2009 oxalate complexation of gadolinium necessitated the draining of the moderator, replacement of the calandria and pressure tubes and removal of gadolinium deposits. Significant reactor safety review was required to ensure the reactor could be safely restarted and controlled predictably. This project required the development of many tools and techniques not previously used at Pickering. (author)