Software of Safety Important I&C Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 160

2. Partial Independence: Verification is
carried out by other experts of the same
organization, and their administrative and/
or financial independence from the software
developers is not required. In this case
there can be partial administrative and/or
financial independence, if the verification
is conducted by experts of a different sub-
division of the organization, for example by
representatives of quality control service,
are subordinate directly to the director.
3. Minimal Independence: Verification is
conducted by the developers themselves,
and the review of its results is performed
by other experts.

proposed by specialists of the expert analysis
organization, and tools of both the inspected
and inspecting organizations are used.

3. Independent sampling evaluation (recheck)

of results of the verification of the most im-
portant functions from the safety standpoint
is carried out, which is made by the developer
organization.

Quality of verification: The use of independent
verification and validation techniques allows one
to improve the quality of this process. By software
verification quality we can mean the degree of
conformity of software to regulatory require-
ments after it is carried out and elimination of any
discovered defects.
The verification quality is evaluated by ana-
lyzing fulfillment of the following requirements:

By means of the technology of independent
verification and validation (IV&V) one can imple-
ment the principle of diversity with respect to the
software creation process. In order to assure the
highest degree of verification it is necessary that
one use tools (utilities), that are different from
those which the developer used.
It should be noted that conducting an indepen-
dent verification can be accomplished according to
different systems and with different depth, which
depends on the software safety class, worthwhile
tasks and existing resources.
Actually three basic scenarios of verification
implementation are possible:

1. Requirements to staging of the process. The
essence of the requirement consists in that
the verification must be carried out after each
software development stage (specification,
design, and coding and others).
2. Requirements to verification of software
conformity to requirements of norma-
tive documents (general requirements for
characteristics and software development,
described earlier) and specifications (func-
tional requirements).
3. Requirements to order of elimination of
any discovered defects and malfunctions.
Components of this requirement are con-
stituents of the process of elimination of
defects, time periods for defect elimination,
conformity of the time periods of elimination
of defects to the software safety class. The
process of eliminating defects, independent
of the software safety class, includes that
a mandatory stabilizing when discovered
in the process of development, testing and
verification; analysis of the causes, degree

1. Full verification and validation of the entire
project is carried out, which repeats practi-
cally all stages of verification within limits
of the project, using intrinsic (diverse) tools
and methodologies.

2. Independent consecutive evaluation (re-

checking) of all results of the verification
performed by the developer organization
is carried out. In this case all checks are
conducted that are stipulated by the verifica-
tion and validation plans, and also checks