Original scientific paper
Basic Relation between RAW and RRW and Some of Its Implications on Risk Reduction Strategies
Ivan Vrbanić,
orcid.org/0000-0001-8769-1729
; APOSS d.o.o. Repovec 23B, 49210 Zabok, Croatia
Ivica Basić
orcid.org/0000-0002-9496-549X
; APOSS d.o.o. Repovec 23B, 49210 Zabok, Croatia
Pranab K. Samanta
; Nuclear Science and Technology Department Brookhaven National Laboratory, Bldg. 130 Upton, NY 11973-5000, United States of America
Abstract
In using risk-informed approaches for ensuring safety of operating nuclear power plants
(NPPs), risk importance measures obtained from probabilistic safety assessments (PSAs) of the
plants are integral elements of consideration in many cases. In PSA models and applications
associated with NPPs the risk importance of a particular feature (e.g. function, system, component,
failure mode or operator action) can be, most generally, divided into two categories: importance
with respect to risk increase potential and importance with respect to risk decrease potential. The
representative of the first category, as used for practical purposes, is Risk Achievement Worth
(RAW). Representative of the second category, as mentioned in consideration of risk importance, is
Risk Reduction Worth (RRW). It can be shown that the two risk importance measures, RAW and
RRW, are dependent on each other. The only parameter in this mutual dependency is probability of
failure of the considered feature. The paper discusses the relation between RAW and RRW and
some of its implications, including those on the general strategies for the reduction of risk imposed
for the operation of the considered facility. Two general risk reduction strategies which are
considered in the discussion are: a) risk reduction by decreasing the failure probability of the
considered feature; and b) risk reduction while keeping the failure probability of the considered
feature at the same level. Simple examples are provided to illustrate the differences between two
strategies and point to main issues and conclusions.
Keywords
Hrčak ID:
247104
URI
Publication date:
28.10.2019.
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