Value chain · CLM-1471
In plain terms
Britain's nuclear power stations were not running at full output for much of the time. From 2012 to 2022, planned and unplanned shutdowns cost the older reactors about a fifth to a third of the electricity they could have made, and the newest, Sizewell B, about a seventh.
The claim as recorded
The IAEA's 2023 reference tables give the UK's nine operating reactors (as of 31 December 2022) unit capability factors averaged over 2012-2022 of 67.3 to 79.1 per cent for the eight advanced gas-cooled reactors at Hartlepool, Heysham and Torness, and 85 per cent for Sizewell B. By the IAEA's definitions, the remainder is energy lost to planned and unplanned outages and load reductions under plant management control: about 21 to 33 per cent of each AGR's potential output over those years, and 15 per cent of Sizewell B's (our arithmetic).
Evidence behind this: T3: an IAEA reference data publication compiled from its Power Reactor Information System.
Scope and limits
These are averages over 2012-2022, not single-year figures and not lifetime figures. The table does not split planned from unplanned loss for each reactor. External losses (XEL, causes outside plant management control) are excluded from UCF but included in EAF, which is lower by 0.2 to 1.5 points. The AGRs are old plants near the end of their lives (SRC-792 paragraph 60), and Hartlepool and Heysham 1 are due to stop by 2027 (SRC-792 PDF p.21), so these figures describe the existing fleet, not a new reactor. The "about a seventh" in plain rounds 15 per cent.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Table 14, read at a zoom 4 crop; the table is printed sideways: column headers "EAF % 2012 - 2022" and "UCF % 2012 - 2022". UK rows, EAF then UCF: Hartlepool A-1 69.8, 70; Hartlepool A-2 71.4, 71.6; Heysham A-1 68.3, 68.6; Heysham A-2 66.8, 67.3; Heysham B-1 78.5, 79.1; Heysham B-2 78, 78.9; Torness-1 77.4, 78.9; Torness-2 76.5, 77.5; Sizewell B 84.2, 85. PDF p.11 (printed p.4): UCF (%) = (REG - PEL - UEL) / REG x 100. PDF p.12 (printed p.5): planned energy loss is energy not supplied because of planned shutdowns or load reductions under plant management control; losses count as planned "if they are scheduled at least four weeks in advance", and unplanned losses are those not scheduled that far ahead (paraphrase outside the quote marks). 100 minus UCF: 30.0, 28.4, 31.4, 32.7, 20.9, 21.1, 21.1, 22.5 and 15.0.
Basis: per cent of reference energy generation, averaged over 2012-2022 as the column headers state; capability loss is 100 minus UCF (our arithmetic, by the page's definitions).
Related records
- Answers question
- QST-021 not published in this release
Cite this
energyaperture.com/c/clm-1471
CLM-1471, Energy Aperture, as of 2023-08.
Connected records
Other published records linked to this one. A list, not a judgement.
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