There are basically two decommissioning options to choose from when dismantling nuclear power plants:

— Dismantle immediately, as soon as the rundown phase has been completed

— Safe confinement: after the rundown phase, put the nuclear power plant into ‘safe confinement’ for around 30 years before starting to demolish it

Immediate dismantling

— Demolish all contaminated and active building sections, systems and components immediately

— Prepare and pulverise all radioactive waste for interim or final storage

— Decontaminate and release other remains

— Decontaminate and release building, demolish conventionally

Safe confinement

— Demolish all contaminated structures, systems and components outside the con­tainment area immediately

— Reduce control area and prepare and pack radioactive waste involved for interim or final storage.

— Decontaminate and clear other residuals involved

— Clear media (press, TV etc.) if possible

— Leave active structural components (nuclear installations, pressure vessel, bioshield) as installed, seal system interfaces appropriately

— Continue to operate essential systems during safe confinement (ventilation, pres — surisation, monitoring systems)

— Confine safely for 25-30 years

— Apply for dismantling permit during safe confinement phase (around five years before safe confinement ends)

— Create new infrastructure facilities

— Demolish and clear plant as with immediate demolition

— Timescale:

Establish safe confinement: 5-8 years Operate in safe confinement mode: 25-30 years Demolish completely: 8-10 years

In Germany, the only nuclear power plants that have been put into safe confinement are Lingen (KWL) and Hamm-Uentrop (THTR). In the light of experience gathered with dismantling projects to date, the prevailing view today is that starting dismantling as soon as the rundown phase is complete is preferable. The advantages include: the nominal costs of direct dismantling are less than those of safe confinement, plant personnel are still on hand, personnel can continue to be employed and the site can be available to be reused sooner if required. The considerations in favour of safe confinement include reducing potential activity in the plant from radioactive decay, possibly using technical innovations and developments and reducing immediate costs.