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Overview of Accident Prognosis Methodology and Reactor Assessment Product Tool at CNSC-EOC

Abstract of the technical presentation presented at:
IAEA Consultancy Meeting
Vienna, November 19–21, 2018

Prepared by:
Mohamed E. Shawkat
Canadian Nuclear Safety Commission


This presentation has two parts, which are:

  1. Accident Prognosis Methodology
  2. Reactor Assessment Product (RAP)

The first part provides an overview of the 4D/4P methodology that CNSC Emergency Operations Centre (EOC) is currently using for nuclear accident diagnosis and prognosis in CANDU reactors. The four fission products barriers in CANDU reactors, their safety systems and safety functions are discussed. The implementation objectives and approaches of the 4D/4P in case of Design Basis Accidents (DBAs) and Beyond Design Basis Accident (BDBAs) are discussed in detail. A summary is given for the prognosis tools used to predict the availability of the safety systems, margins of the safety functions and the integrity of the safety barriers (or the timing of fission product releases in case of BDBAs).

In the second part, an overview of the RAP tool that the CNSC-EOC is using to graphically present the status of the safety systems in the CANDU nuclear plant and the possibility of fission products release during different phases of accident progression. The 4D/4P results are the main source to fill the inputs of the RAP; however, other sources may be used such as plant general information and technical judgment. The tool graphical outputs are illustrated for a generic CANDU case. CNSC-EOC uses the RAP as an internal and external communication tool. The IAEA Reactor Assessment Tool (RAT) to be sent to IAEA is prepared based on the RAP.

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