Load factors to end June 2001

30 October 2001

Table 1 lists nuclear units over 150MWe in order of their achievements as measured by the annual load factors for the 365 days ending 30 June 2001. Yet again, no data was available for the Indian units (with the sole exception of Tarapur) and three stations in the USA, Arkansas, Limerick and Nine Mile Point 1 were also unobtainable.

Once more, there is a very creditable number of full marks winners in the top ten annual load factors, and a record number of US reactors – the top three, and four more. This improvement in the national nuclear energy performance is reflected in Figure 7 and the corresponding table of country performances. These show that the USA has climbed to 9th out of the twenty countries that operate more than three units, in spite of the fact that this country operates nearly a quarter of the total units in this part of the table.

The quartiles breakdown shows an improvement over the year-ago figure, the best improvement being in the top one then the second and third in order, a welcome reversal of a trend that seemed to be becoming established.

Both PWRs and BWRs improved the annual load factors over the end-March quarter, but were down a little on this month a year ago. The Canadian PHWRs declined a little compared with either March or last year’s June quarters. The Russian RBMK units had a small improvement over both quarters. A possible reversal of declining fortunes are observed in the AGR units in the UK, which some years ago enjoyed a brief spell as the top performing reactor type after a long spell struggling upwards – and then started to drop once more. In June, both the British AGRs and the remaining Magnox units improved their output over both the previous quarter and over the end-June quarter last year.

Lifetime average performances change more slowly, but do manage to confirm or deny suspected trends. In the individual units, Wolsong 2 replaces Yonggwang (both from South Korea in about the 8th position, the remainder not changing much. Fourth place TVO-1 was the best top life performer that did not slip down a little since the end of March this year.

The top ten for TWh gross output remained exactly the same as for the last quarter. Philippsburg 2 is the only unit at present that appears in both these tables. However, the large proportion of units from Germany in both tables is indeed ironic in the light of the growing rumours about accelerated nuclear plant closures. The 1410MWe gross Unterweser was the world’s first nuclear power station to pass a lifetime total generation of 200TWh. This it achieved with a lifetime capacity factor of just under 80%.

Would someone of the most fanatical anti-nuclear power persuasion like to list how many single power station units have exceeded that amount of output. If there are any, perhaps they would then care to estimate the weight of carbon such a unit has released into the Earth’s atmosphere. Then estimate how many non-carbon producing energy generation options exist that could collectively achieve such a high lifetime load factor. And, while they are about it, please also work out how much they would cost, what area of land they would need to cover, and what the embedded energy of the non carbon-producing alternative would be. No cheating!

Load factor tables

Units listed include all the reactors of 150 MWe and above from which we regularly receive adequate monthly data. Annual load factors for units over the 12 months to end June 2001, and lifetime (which are also called cumulative) load factors, to end June 2001, are presented in Tables 1 and 2. The figures are calculated on the same basis as that used since early 1976 so that trends can be established. Annual load factors are calculated by dividing the gross generation of a reactor in a one-year period by the gross capacity of the reactor (sometimes called output), as originally designed, multiplied by the number of hours in the calendar year. The figures are expressed as percentages. Where a plant is uprated, the revised capacity is used from the date of the uprating. Similarly, lifetime (also called cumulative) load factors are calculated by dividing the gross generation from the date of first synchronisation (not the date of commercial operation, which can be many months after the plant is generating power) by the gross capacity multiplied by the number of hours elapsed since the first synchronisation. These figures are also expressed as percentages. It is important to note that load factors alone can be a misleading measure of performance, for example when a utility is deliberately operating reactors below their full capacity, for load following or where hydro power is available and is used preferentially. Figure 1 shows how the average load factors for the six main reactor types have changed over the years. Figure 2 attempts to convey the lifetime load factors for each reactor type and the amount of electricity that has been generated so far by each type. Figure 3 shows the annual and the lifetime load factors for the six main reactor types. Figure 4 conveys the country lifetime average load factors and lifetime nuclear generation for each country. Figure 5 compares the load factor average over the 12 months to end June 2001 with that for the 12 months to end June 2000, for the six main reactor types. Figure 6 shows load factor quartiles. Figure 7 shows the PWR and and the BWR averages for countries with four or more of each reactor type. Figure 8 shows the country annual average load factors over time. In addition to Tables 1-2, three other tables are included: a summary of country data; the top ten reactors in terms of lifetime load factors; and the top ten reactors in terms of electricity production.

Reactor type abbreviations

P=PWR, B=BWR, H=Heavy water (pressurised), M=Magnox, A=AGR, R=RBMK, F=Fast Reactor Ranking: Load factors are only shown in the table to one place of decimals, but ranking is on the basis of three places of decimals


Country averages as at end June 2001
Table 1. Annual and lifetime average load factors to end June 2001, for reactors of 150 MWe and above
Table 1. Annual and lifetime average load factors to end June 2001, for reactors of 150 MWe and above. Continued I
Table 1. Annual and lifetime average load factors to end June 2001, for reactors of 150 MWe and above. Continued II
Table 1. Annual and lifetime average load factors to end June 2001, for reactors of 150 MWe and above. Continued III

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