TY - BOOK
T1 - Probabilistic safety goals. Phase 2 status report
AU - Holmberg, Jan-Erik
AU - Björkman, Kim
AU - Rossi, Jukka
AU - Knochenhauer, Michael
AU - He, Xuhong
AU - Persson, Anders
AU - Gustavsson, Helena
N1 - Project code: 13107-1.1
PY - 2008
Y1 - 2008
N2 - The second phase of the project, the outcome of which is described in
this pro-ject report has mainly dealt with four issues: Consistency in the
usage of safety goals, Criteria for assessment of results from PSA level 2,
Overview of international safety goals and experiences from their use, Safety
goals related to other man-made risks in society. Consistency in judgement
over time has been perceived to be one of the main problems in the usage of
safety goals. Safety goals defined in the 80ies were met in the beginning with
PSA:s performed to the standards of that time, i.e., by PSA:s that were quite
limited in scope and level of detail compared to today’s state of the art.
This issue was investigated by performing a comparative review was performed
of three generations of the same PSA, focusing on the impact from changes over
time in component failure data, IE frequency, and modelling of the plant,
including plant changes and changes in success criteria. It proved to be very
time-consuming and in some cases next to impossible to correctly identify the
basic causes for changes in PSA results. A multitude of different sub-causes
turned out to combined and difficult to differentiate. Thus, rigorous
book-keeping is needed in order to keep track of how and why PSA results
change. This is es-pecially important in order to differentiate “real”
differences due to plant changes and updated component and IE data from
differences that are due to general PSA development (scope, level of detail,
modelling issues).
AB - The second phase of the project, the outcome of which is described in
this pro-ject report has mainly dealt with four issues: Consistency in the
usage of safety goals, Criteria for assessment of results from PSA level 2,
Overview of international safety goals and experiences from their use, Safety
goals related to other man-made risks in society. Consistency in judgement
over time has been perceived to be one of the main problems in the usage of
safety goals. Safety goals defined in the 80ies were met in the beginning with
PSA:s performed to the standards of that time, i.e., by PSA:s that were quite
limited in scope and level of detail compared to today’s state of the art.
This issue was investigated by performing a comparative review was performed
of three generations of the same PSA, focusing on the impact from changes over
time in component failure data, IE frequency, and modelling of the plant,
including plant changes and changes in success criteria. It proved to be very
time-consuming and in some cases next to impossible to correctly identify the
basic causes for changes in PSA results. A multitude of different sub-causes
turned out to combined and difficult to differentiate. Thus, rigorous
book-keeping is needed in order to keep track of how and why PSA results
change. This is es-pecially important in order to differentiate “real”
differences due to plant changes and updated component and IE data from
differences that are due to general PSA development (scope, level of detail,
modelling issues).
KW - Safety Goals
KW - PSA
KW - Safety Targets
KW - ALARP
KW - Decision criteria
KW - Risk informed decision making
M3 - Report
SN - 978-87-7893-238-9
T3 - NKS Reports
BT - Probabilistic safety goals. Phase 2 status report
PB - Nordic Nuclear Safety Research NKS
ER -