IAEA, Vienna, 2003, 242 p. IAEA-TECDOC-1361
ISBN 92–0–108003–4, ISSN 1011–4289
At present, there are over four hundred operational nuclear power plants (NPPs) in
IAEA Member States. Operating experience has shown that ineffective control of the ageing
degradation of the major NPP components (caused for instance by unanticipated phenomena
and by operating, maintenance or manufacturing errors) can jeopardize plant safety and also
plant life. Ageing in these NPPs must therefore be effectively managed to ensure the
availability of design functions throughout the plant service life. From the safety perspective,
this means controlling, within acceptable limits, the ageing degradation and wearout of plant
components important to safety so that adequate safety margins remain, i.e. integrity and
functional capability in excess of normal operating requirements.
This TECDOC is one in a series of reports on the assessment and management of
ageing of the major NPP components important to safety. The reports are based on experience
and practices of NPP operators, regulators, designers, manufacturers, technical support
organizations and a widely accepted Methodology for the Management of Ageing of NPP
Components Important to Safety, which was issued by the IAEA in 1992. Since the reports are
written from a safety perspective, they do not address life or life cycle management of plant
components, which involves economic considerations.
The current practices for the assessment of safety margins (fitness-for-service) and
the inspection, monitoring and mitigation of ageing degradation of selected components of
Canada deuterium–uranium (CANDU) reactors, boiling water reactors (BWRs), pressurized
water reactors (PWRs), and water moderated, water cooled energy reactors (WWERs) are
documented in the reports. These practices are intended to help all involved directly and
indirectly in ensuring the safe operation of NPPs, and to provide a common technical basis for
dialogue between plant operators and regulators when dealing with age-related licensing
issues. The guidance reports are directed at technical experts from NPPs and from regulatory,
plant design, manufacturing and technical support organizations dealing with specific plant
components addressed in the reports.
This report addresses the primary piping in PWRs including main coolant piping,
surge and spray lines, Class 1 piping in attached systems, and small diameter piping that
cannot be isolated from the primary coolant system. Maintaining the structural integrity of this
piping throughout NPP service life in spite of several ageing mechanisms is essential for plant
safety.
