 Economic, energy security and environmental grounds were given as reasons to build the fifth reactor.While hydroelectricity is curtailed in dry years (range 9,455–14,865 GWh 1990–2006 ), nuclear energy supplies near-constant amounts of energy, and studies showed that nuclear energy was the cheapest option for Finland.The vote was seen as very significant for nuclear energy policy in that it was the first decision to build a new nuclear power plant in western Europe for more than a decade.