Nuclear Plant Journal, March-April 2015 NuclearPlantJournal.com
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Basic and FORTRAN to C/C++ and C#.
Communication networks range from
none, serial and proprietary to the latest
Ethernet fiber redundant architectures.
The most primitive devices still in use are
peripherals such as dot matrix printers,
analog recorders, early technology analog
and ASCII displays, first generation
graphical displays, etc. At least 50
percent of the “current” PPCs have many
of these original technology attributes.
Perhaps even more important
than obsolescent parts are obsolescent
integration schemes. Early systems,
driven in large part by old technology,
were integrated monoliths - one system
element was completely dependent on
another to create the functionality that
was required. Today any system worth
having is modular with no architectural
or functional dependencies. This enables
modular function replacement. When
properly managed, there is no reason that
a modular system cannot be maintained,
updated and improved on-line for the
rest of the plant operating life including
decommissioning.
Exhibit 1 provides perspective on
the age of systems in service today. The
content must be tempered with the fact
that the vast majority of PPCs more than
ten years old have been heavily modified,
partially upgraded and even had their
software completely rewritten by plant
technical staffs.
It is important to note that the very
act of adapting and improvising, by
what is now a retiring workforce, is a
significant contributor to the difficulty of
Exhibit 1 describes the technological age of each PPC in US operating fleet, the
majority of which are significantly more than 10 years old.
