Nuclear Energy for New Europe 2009

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No: 310

Conference: Nuclear Energy for New Europe 2009

Title: Implementation of Level 2 PSA for Internal Events into RiskSpectrum PSAP Model

Theme: Probabilistic Safety Assessment

Author(s): Rudolf Prosen, Ivan Košutić

Contact : Rudolf Prosen

E-mail: rudolf.prosen@nek.si

Address: Nuklearna elektrarna Krško
8270 Krško

Country: Slovenia

The existing Level 2 PSA calculations were performed using external post processing of bridge tree sequence results. This type of calculation is time consuming and impractical for regular use.
Till this implementation only a part of Level 2 model was present in the PSA model, the bridge trees. When calculating the Level 2 Release Frequencies (RF) or Large Early Release Frequency (LERF) the PSA model did only a part of needed calculations. The results, bridge tree sequences, were exported to a file, grouped in Plant Damage States (PDS) and post-processed by use of different tools.
To get the final result by the RiskSpectrum tool and PSA model, the Containment Event Tree (CET) split factors needed to be implemented in the model. It was accomplished with the formation of split factors event trees that represent the solution of the Containment Event Tree. The result is the single consequence called LERF or release category consequences RC1 to RC 8 (also A and B where applicable).
The first important outcome of this integration is that it enables the calculations of LERF within the PSA model without the need for exporting and external post processing of intermediate results. Another also very important outcome, are importance and uncertainty factors that can be calculated with this model.
The paper describes the overall process of implementation of Level 2 event trees into the PSA model, and presents its results.

No:	310
Conference:	Nuclear Energy for New Europe 2009
Title:	Implementation of Level 2 PSA for Internal Events into RiskSpectrum PSAP Model
Theme:	Probabilistic Safety Assessment
Author(s):	Rudolf Prosen, Ivan Košutić
Contact :	Rudolf Prosen
E-mail:	rudolf.prosen@nek.si
Address:	Nuklearna elektrarna Krško 8270 Krško
Country:	Slovenia

The existing Level 2 PSA calculations were performed using external post processing of bridge tree sequence results. This type of calculation is time consuming and impractical for regular use. Till this implementation only a part of Level 2 model was present in the PSA model, the bridge trees. When calculating the Level 2 Release Frequencies (RF) or Large Early Release Frequency (LERF) the PSA model did only a part of needed calculations. The results, bridge tree sequences, were exported to a file, grouped in Plant Damage States (PDS) and post-processed by use of different tools. To get the final result by the RiskSpectrum tool and PSA model, the Containment Event Tree (CET) split factors needed to be implemented in the model. It was accomplished with the formation of split factors event trees that represent the solution of the Containment Event Tree. The result is the single consequence called LERF or release category consequences RC1 to RC 8 (also A and B where applicable). The first important outcome of this integration is that it enables the calculations of LERF within the PSA model without the need for exporting and external post processing of intermediate results. Another also very important outcome, are importance and uncertainty factors that can be calculated with this model. The paper describes the overall process of implementation of Level 2 event trees into the PSA model, and presents its results.