ASNR (previously IRSN) develops and maintains its probabilistic software KANT, to fulfil the needs of the ASNR level 2 PSA (L2 PSA) project. KANT has been designed as a user-friendly tool and allows the user to represent the L1-L2 PSA interface, to represent the accident progression event tree (APET), to quantify the frequency of accidental sequences and perform grouping into release categories, to calculate the radioactive release and radiological consequences for each release category and to perform uncertainty analysis by Monte-Carlo simulation.
KANT addresses four main needs of the L2 PSA project: 1/ a detailed L1-L2 interface with a large number of plant damage states (PDS); 2/ a large number of events in the APET, and the ability to describe them in a simple programming language (e.g. for logical functions about system availability or human reliability analysis), or to call external libraries (e.g. surrogate physical models in C++); 3/ the propagation of physical global variables describing the plant state through the successive events (they affect the probabilities of events or the classification of sequences into release categories); 4/ a unique APET for all accidents considered in L2 PSA.
KANT underwent major changes in 2025, with a rewrite of its graphical user interface, and shortened load times thanks to the adoption of a much faster interpreter for its runtime language.
The paper provides an overview of the current state of KANT, notably its interface and its language, and perspectives for its future.