Environmental Engineering Reference
In-Depth Information
Chapter 6
Diversity and Multi-
Version Systems
Alexander Siora
Research and Production Corporation Radiy, Ukraine
Vladimir Sklyar
Research and Production Corporation Radiy, Ukraine
Vyacheslav Kharchenko
National Aerospace University named after N.E. Zhukovsky KhAI,
& Centre for Safety Infrastructure-Oriented Research and Analysis, Ukraine
Eugene Brezhnev
Centre for Safety Infrastructure-Oriented Research and Analysis, Ukraine
ABSTRACT
To protect safety-critical systems from common-cause failures that can lead to potentially dangerous
outcomes, special methods are applied, including multi-version technologies operating at diferent lev-
els of diversity. A model representing diferent diversity types during the development of safety-critical
systems is suggested. The model addresses diversity types that are the most expedient in providing
required safety. The diversity of complex electronic components (FPGA, etc.), printed circuit boards,
manufacturers, speciication languages, design, and program languages, etc. are considered. The chal-
lenges addressed are related to factors of scale and dependencies among diversity types, since not all
combinations of used diversity are feasible. Taking these dependencies into consideration, the model
simpliies the choice of diversity options. This chapter presents a cost efective approach to selection of
the most diverse NPP Reactor Trip System (RTS) under uncertainty. The selection of a pair of primary
and secondary RTS is named a diversity strategy. All possible strategies are evaluated on an ordinal
scale with linguistic values provided by experts. These values express the expert's degree of conidence
that evaluated variants of secondary RTS are diferent from primary. All diversity strategies are evalu-
ated on a set of linguistic diversity criteria, which are included into a corresponding diversity attribute.
The generic fuzzy diversity score is an aggregation of the linguistic values provided by the experts to
obtain a collective assessment of the secondary RTS's similarity (diference) with a primary one. This
rational diversity strategy is found during the exploitation stage, taking into consideration the fuzzy
diversity score and cost.
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