Link to the study - European Parliament - Europa

Nuclear Decommissioning: Management of Costs and Risks
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Sizes of reactors in shutdown mode
In decommissioning projects, the size of the reactor plays a role with regard to certain aspects (e.g.
the accumulated spent fuel, the amount of generated decommissioning wastes, time and workforce
requirements and the size-dependent part of the total decommissioning costs). Figure 2 therefore
displays the size distribution of reactors currently in shutdown mode.
Figure 2: Size distribution of reactors in shutdown state
50
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Size distribution of reactors in shut down state
# of reactors
43
40
35
30
25
20
15
10
10
13
14
8
5
0
< 50 MW 50..100 100..500 500..1000 > 1000
Gross power per unit (MWel)
Source: Authors, data derived from the IAEA-PRIS database (PRIS 2013)
As can be seen in Figure 2 about half of the reactors currently under shutdown are in the range
between 100 to 500 MW. So the majority of those reactors does not belong to the smallest
500 MWel. The decommissioning of
reactors of the 50..500 MWel classes is considerably more complex, cost-intensive and complicated
than that of small research or production reactors (not included here) of the 10 MW size (due to the
number of systems, the size of equipment, the masses involved, etc.). On the other hand the
decommissioning of reactors of the smaller sizes (e.g. 100..500 MW) class can serve as a field to gain
experiences that will be necessary and valuable for the larger sizes to be decommissioned.
Operating time of reactors in shutdown state
The time over which the reactors were operated plays a further role for decommissioning. While the
reasons for shutting down are manyfold (technical, safety, economical, legal, etc.) and specific in each
case the operating time plays a general role for decommissioning. The longer the reactors are
operated the more fuel accumulates, the higher is the neutron activation of reactor internals and of
the bio shield, the deeper the contamination of surfaces and structures. This leads to a higher chance
that locations and materials, to be cleaned-up and handled during decommissioning, are
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