Diversity and Multi-Version Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 193

Figure 5. Architecture variants of two-version I&C systems

• Diversity depth (I&Cs with a common ϑO
and separate ϑS diversity); it should be
noted that this feature is applicable only to
the full system diversity.

In general case I&C system LC is a sequence
of N stages. At each i-th stage of a multi-version
I&C system LC Mi of diversity types may be
applied. From Mi, i = 1,...,N; diversity types only
a single j-th type, j = 1,...,Mi, may be selected.
Besides, at each i-th stage of LC a single-version
development technology may be selected. Each
j-th diversity type at each i-th LC stage is char-
acterized by two indices: diversity metrics (depth)
dij and cost of a respective diversity type applica-
tion (a cost increase as compared to a single-
version option of each i-th LC stage).
Thus, a set of solutions on selection of diversity
type is described by two matrices: diversity metrics
values D = || d ij || and cost values С = || с ij ||. Hence,
MVS LC may be presented as a bipolar N-level
graph (Figure 7) called a graph of multi-version

Models of Multi-Version Life
Cycle and Technology

A model of MVS life cycle (or multi-version
LC model) is based on operations of the version
generation G, the aggregation and selection U at
various stages (Kharchenko et al., 2007). Example
of the two-version life cycle model is shown on
Figure 6 taking into account some FPGA-oriented
design features (V ij are different versions obtained
on different stage of development) (Prokhorova
et al., 2008).