How plant life extension works
The feasibility of plant lifetime extension (PLEX), sometimes known as asset sweating, depends on both safety and economic factors. To make plant life extension financially worthwhile, the projected extra income from wholesale electricity sales must exceed the increased operating and maintenance costs from running the reactor for longer.
The energy utility must also obtain safety clearance from the nuclear regulatory body approving a five or 10 year period safety review (PSR). In 2005 British Energy (now owned by EDF) announced a 10-year life extension of the Dungeness-B AGR which will operate until 2018, and in 2008 announced a 5-year life extension of the Hinkley-B and Hunterston-B AGRs which will operate until 2016.
For an energy utility company, reactor plant life extension is much more economically attractive compared with the financial risk of new nuclear build. The older reactor is highly cash-generative because interest from its construction debt is already paid-off, whereas new nuclear build reactors do not become significantly profitable until after they have reached their 17 year capital payback period.
Plant life extension is also attractive for government energy policy, because it buys extra time for investment in low carbon technologies and maximises the UK's carbon emission savings from nuclear electricity generation. However the downside is that reactor lifetime extensions may ultimately delay the introduction of new nuclear build, unless the extra profits are diverted to funding new reactor construction.