Life expectancy of nuclear power plants

Surveillance capsules measure reactor vessel degradation

In countries where there is an ongoing public discussion about a nuclear power phase-out, you often hear the phrase ‘the life expectancy of the nuclear power plant’. Strictly speaking however, nuclear power stations do not have a fixed life expectancy.

The initial design lifespan is usually 30 to 40 years. This is the figure used for the financial depreciation of the investment in the plant. However, nearly all elements in a nuclear power plant can be replaced except for the reactor vessel. This is consequently the crucial element in determining the true life expectancy of the plant. The safe and useful life of a reactor vessel depends on the degree to which it is neutron leak proof. This factor is monitored by surveillance capsules.

Re-evaluation every ten years

Nuclear power plants are required to renew their exploitation licence every ten years. A safety commission is assembled when the date for renewal of the licence approaches and they make an assessment regarding whether or not the plant can operate safely for another ten years. One of the means used to make this assessment is by verifying the results of the surveillance capsules.

Consequently, apart from political decisions, the life expectancy of a nuclear power plant is re-evaluated every ten years for an additional decade of operation. Operations will continue if:

• The surveillance capsules prove that the reactor vessel can continue to operate in absolute safety
• All replacement and maintenance investments necessary to guarantee a safe and reliable operation are economically justified

Reference

Speech by Eric van Walle, director-general of the Belgian Nuclear Research Centre SCK-CEN, on the Strategic Forum on Energy Supply in the 21st Century (Brussels, 18 December 2006)