Software of Safety Important I&C Systems - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 175

Solutions and Recommendations

adequate interpretation may be beyond the com-
mon regulatory aspect. In this scope, issues of
personnel training, establishment of effective
communications between the development teams
and the utilities and other become important.
All these issues require systematic study and
comprehensive scientific researches.

Specific features of software development and
usage require proper regulation requirements
towards the program components.
At the same time requirement to software
should be agreed with requirements to I&C sys-
tem. Categories of functions performed by I&C
system have influence with software requirements,
including requirements for composition of the
functions, quality, reliability, stability, interaction
with other components, procedures and processes.
Therefore developing of requirements for soft-
ware components shall be done taking into account
features of target I&C system, international and
national regulatory requirement. For the solution
of this issue systematic approach and methods,
supported with appropriate tools, are required.
Modern model-based methods and techniques
should be applied to assess NPP I&C software, in
particular, model-checking (Lahtinen et al., 2010)
and invariant-oriented evaluation (Kharchenko
(Ed), 2012), software safety analysis techniques
(Hui-Wen Huang et al., 2011) etc.

CONCLUSION

1. Software is a specific object for safety regu-
lation. It is a component of I&C system to
which requirements are applicable, and also
it is a means of ensuring the satisfaction of
regulatory requirements. At the same time
software is the most likely sources of com-
mon cause failures. Therefore the need to
minimize risks of common cause failures
is reflected in the requirements to processes
of software development and verification, as
well as application of diversity.
2. Standardization, evaluation and assurance of
software safety should be based on process-
and-product-approach. I.e. harmonized
requirements for the program as a product
and the processes related to the creation,
evaluation and use of programs at various
stages of the lifecycle should be used.
3. Degree of completeness, adequacy and cor-
rectness of requirements to software is the
determining factor in assessing their compli-
ance, and thus ensure the quality, reliability
and safety of both software and I&C system
of NPP.
4. Methods that are used for software evaluation
should be standardized and cover all aspects
of software development and application. If
it is necessary, correct application of such
methods can be evaluated by experts. From
this point of view special significance is
acquired by criterion of documentation.

FUTURE RESEARCH DIRECTIONS

To match the latest trends and industry requests
software components of I&C systems become
more complex. Development of software engi-
neering technologies also opens up new aspects
and generates new issues for designing and imple-
mentation of software. Therefore possible implica-
tions of new programming technologies must be
analyzed to ensure timely and adequate adaptation
and clarification of regulatory frameworks.
Also attention should be paid to the fact that
in large projects of I&C systems several organi-
zations with different background and possibly
from different countries can participate. Thus
harmonization of requirements and ensure their