Modern nuclear power stations are very reliable. They typically operate continuously for 18 months generating baseload electricity for power grids, before stopping for periodic maintenance outages and refuelling outages.

Average load factors

Historically the average load factor availability of pressurised water reactors world-wide over the past 40 years has been 75%, meaning that on average a typical PWR reactor will generate 75% of its maximum electrical capacity each year. Electricity companies today operate pressurised water reactors much more efficiently, achieving an 83% average load factor world-wide in 2009.

Modern Generation III+ nuclear reactor designs are expected to reach operational load factors of greater than 90%. Maintenance and refuelling outages are very carefully planned in advance so that down-time is minimised and the reactor can resume electricity generation as fast as possible. This is important to earn money for the utility from electricity sales and pay-off interest from the reactor build cost. Older nuclear reactor designs are far less efficient. Britain's Generation I Magnox nuclear power stations have achieved an average load factor of 57% over their lifetime. The Magnox fleet has operated at just over half of its maximum capacity.

shutterstock_1038500134   300

Engineering Policy Unit 

Our Engineering Policy Unit works closely with members to raise the profile of engineers and engineering potential, to generate discussion and provide thought leadership.

Read our policy-related Themes and reports