CURRENT GENERATION REACTORS

15.2. PLANT LIFE EXTENSION

The technical issues associated with plant ageing centre around the ageing of mechanical, electrical and materials ageing of plant components, particularly concretes and steels (Govaerts, 2001). The EC is funding a major research programme on this issue and a selection of some of the on-going projects is summarised below (Table 15.1). Utility practices for the safe management of nuclear power plant ageing in the EU are given in

Table 15.1. EC Research in nuclear fission energy (1998-2002)

Подпись: Operational safety of existing installationsПодпись: Safety of the fuel cyclePlant life extension and management Severe accident management Evolutionary concepts

Waste and spent fuel management

and disposal

Partitioning and transmutation Decommissioning of nuclear installations

Подпись: Innovative and revisited conceptsSafety and efficiency of
future systems

Подпись:Risk assessment and management Monitoring and assessment of occupational

exposure

Off-site emergency management Restoration and long-term management of

contaminated environments

Table 15.2. Plant life extension and related issues

Issues

EC research programmes

Embrittlement of materials

AMES, PISA, FRAME, RETROSPEC, GRETE

Materials corrosion

PRIS, INTERWELD

Fracture mechanics

NESC, SMILE

Concrete ageing

MAECENA, CONMOD

Materials testing

FEUNMARR

Thermal — hydraulics

WAHALOADS

FISA 2001: EU Research in Reactor Safety (2001) and FISA 2003 (to be published).

EUR 19843 (2001). The phenomena include thermal fatigue and stress corrosion, and relate to the thermal and mechanical loads to which the components are subjected. Chemical factors may also be an issue.

There may also be practical factors that present a range of difficulties in presenting a case for life extension; e. g. hardware and software may become obsolete, original suppliers may no longer be able to supply replacements, etc. Computer codes may become outdated and no longer supported by developers. Rules and standards may change. Knowledge may reside in staff who have retired or about to retire, documentation may not be adequate without the presence of experienced original authors. Modern non-destructive testing (NDT) methods may be able to identify defects that had not previously been observed, but also in a positive sense, may be able to confirm the absence of defects (Table 15.2).

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