Diversity and Multi-Version Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 215

Table 8. Results of comparative analysis of diversity assessment techniques

Technique Diversity Classification Number of Level Diversity Metrics Sensibility to

Diversity Type

Tool

NUREG7007-
technique

NUREG6303-based
classification

Two-level
hierarchy

Non-normalized Fixed +

CLB - technique Extensible (in depth)

NUREG7007-based
classification

Multi-level Normalized metric, may

be used to calculate β
factor

May be increased +

GMB - technique Additionally take into account

feature technological and
architectural aspects

Multi-level Normalized metric, may

be used to calculate β
factor

May be increased +

are FPGA-based and which are software and
microprocessor-based; (b) identification of
a product diversity; for FPGA-based MVSs:
manufacturer of chips; FPGA technology;
FPGA families; FPGA chips, languages;
tools, etc); (c) identification of process
diversity types.

Thus, result of this stage is a value of general
diversity metric μ, which is some approximation
of β, and can characterize the diversity effect on
CCF probability.
The third stage is a probabilistic RBD- or MM-
based (RDM) assessment of MVS reliability and
safety. Initial data for the RDM procedure are I&C
design and documentation, results of the CLD
and MAD analysis; results of the RDM procedure
are values of safety and dependability indicators.
Detailed description of the RDM procedure is
given in (Kharchenko et al., 2004).

Results of the analysis are entered in a check-list
in accordance with a rule Yes (if corresponding
diversity type is used in a system) / No (in opposite
case) and is presented as a n-bit Boolean vector.
The second stage is a metric-based assessment
of diversity. This stage contains two operations:

IMPLEMENTATION OF FPGA-
BASED SAFETY-CRITICAL NPP
I&CS: UKRAINIAN EXPERIENCE

1. Determination of metric values for different
types of applied diversity, i.e. performing two
activities: (a) determination of metric values
(local diversity metrics μ i for the diversity
type d i and local diversity metrics μ ij for
the diversity subtype d ij ); the metric values
may be predefined; (b) correction of metric
values in accordance with development and
operation experience.
2. Calculation of general diversity metric μ for
a system: (a) determination (correction) of
weight coefficients ω i (ω ij ) of metrics (taking
into account multi-diversity aspect); sum of
weight coefficients ω i (ω ij ) is equal 1; (b)
convolution (additive or more complex) of
metrics and calculating value of the general
diversity metric μ = Σ ω i Σ ω ij μ ij , i = 1,…,
n; j = 1,…n i .

General Description of the
FPGA-Based RADIY Platform

The platform RADIY produced by RPC Radiy is
an example of a dependable and scalable FPGA-
based I&C platform ensuring possibility of devel-
opment of multi-version systems. Dependability
assurance feature of the I&C platform RADIY
is a multi-diversity implementation through the
following diversity types: equipment diversity
is provided by different electronic components,
different programmable components (FPGAs
and microcontrollers) and different schemes of
units; software diversity is provided by different
programming languages and different tools for