Permanent Start-Up Instrumentation for Maintenance Outages
9th International Conference on CANDU® Maintenance - 2011 December 04-06

Presented at:
9th International Conference on CANDU® Maintenance
2011 December 04-06
Toronto, Canada
Session Title:
Industry Performance Special Session A1

Jerry M. Cuttler (Cuttler & Associates Inc.)
Elnara Nasimi (Bruce Power)
H. Gill (Bruce Power)
R. Scrannage (Bruce Power)
Philippe Paquette (Bruce Power)


This paper assesses the need and feasibility of permanent start-up instrumentation detectors to monitor photoneutron flux during maintenance outages. CANDU® ion chamber systems were designed to remain on scale for ten weeks after reactor shutdown. A requirement was imposed in the mid-1990s to put the reactor into an overpoisoned guaranteed shutdown state whenever it is shut down and not actively undergoing a restart. Due to the high gadolinium concentration, the ion chamber systems go off scale within three weeks. Operating policies and procedures require the neutron flux and its rate of change to be monitored when fuel is in the reactor.

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