Performance of Ontario’s CANDU nuclear generating stations in 2016

April 3, 2017

By: Donald Jones, P.Eng., retired nuclear industry engineer, 2017 March 31

At the end of 2016 Darlington had a four unit average lifetime Capacity Factor (CF) of 83.6 percent and an average annual CF of 83.6 percent. Bruce A had a four unit average lifetime CF of 69.4 percent and an average annual CF of 81.9 percent. Bruce B had a four unit average lifetime CF of 83.5 percent and an average annual CF of 82.3 percent. The six unit Pickering station had a six unit average lifetime CF of 72.5 percent and an average annual CF of 73.6 percent. More information, and performance data for 2015 are in reference 1.

The raw performance data for 2016 are taken from the Power Reactor Information System (PRIS) database of the International Atomic Energy Agency (IAEA). Note that the Load Factor term used in the PRIS database has the same meaning as CF. CFs are based on the (net) Reference Unit Power and on the (net) Electricity Supplied, as defined in the PRIS database.

The performance of some of Ontario’s nuclear generating stations is affected by the surplus baseload generation (SBG) in the province. The surplus usually arises because of unreliable intermittent wind generation coming in at times of low demand and wind generation is expected to increase even more over the next several years. Some nuclear units saw electricity output reductions during periods of surplus baseload generation (SBG). This means the CFs are not a true performance indicator for those units (reference 2). A better metric of performance in these cases would be the Unit Capability Factor (UCF – used by Ontario Power Generation and by Bruce Power). The Energy Availability Factor (EAF) is another performance indicator and is shown in the PRIS database. The EAF adjusts the available energy generation for energy losses attributed to plant management, planned and unplanned, and for external energy losses beyond the control of plant management while the UCF only includes energy losses attributed to plant management and excludes the external losses beyond control of plant management like load cycling/load following, grid failures, earthquakes, cooling water temperature higher than reference temperature, floods, lightning strikes, labour disputes outside the plant etc.

For Ontario there should be little significant difference between CF, UCF and EAF for units that do not load cycle (an external energy loss) since other external energy losses will be close to zero. For units that load cycle the UCF will be higher than the EAF and higher than the CF but the EAF should not be significantly different from the CF. For example, from PRIS data, Bruce B unit 5 has a 2016 annual CF of 94 percent and an EAF of 97.4 percent. However based on what was just said above this EAF of 97.4 percent must really be a UCF of 97.4 percent and this anomaly may apply to all EAFs given in this article! The UCF and the EAF are based on reference ambient conditions so, unlike the CF, they cannot exceed 100 percent. In some cases the CF can be more than the EAF because the cooling water temperature is lower than the reference temperature and that increase the electrical output of the unit.

All manoeuvred reductions in electrical output from Ontario’s nuclear stations to accommodate the much more expensive wind generation are done by the flexible Bruce A and Bruce B stations using turbine steam bypass to condenser and they get paid for the lost revenue. Of course it makes little environmental, economic or technical sense to reduce the low cost output from nuclear stations, with practically zero greenhouse gas emissions, to accommodate expensive unreliable wind generation on the grid that is not needed anyway. The provincially owned Darlington and Pickering stations do not manoeuvre but would have to come off line to accommodate wind and they would not get paid for the lost revenue. While the Bruce electricity output reductions are easily seen from the hourly Generator Output and Capability Report on the website of Ontario’s Independent Electricity System Operator (IESO) it is more difficult to know if nuclear unit shutdowns are to mitigate SBG or are due to forced outages. Maybe an outage was extended, or a planned outage was rescheduled, to accommodate anticipated SBG. However, according to the Bruce Site Updates website there appeared to be be just one overnight shutdown, on unit 2, caused by SBG.
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More wind generation on Ontario electricity grid means more pollution

January 12, 2015

By: Donald Jones, P.Eng., retired nuclear industry engineer, 2015 January

It seems that the more wind there is on the Ontario electricity grid the more pollution there is. Case in point, a snapshot of the Independent Electricity System Operator’s (IESO) Generator Output and Capability Report for 2015 January 8 at 7 pm, which was a high wind high demand day. Wind was generating 2,631 MW, natgas or frackgas was generating 3,783 MW with the balance of the demand being met by nuclear and hydro. There were net exports of 3,500 MW. Now if there were no exports, natgas generation could have been reduced to 283 MW (assuming this low generation were achievable technically and under the must-run contracts) with a clean supply of nuclear, hydro and wind meeting the major part of the Ontario demand. Obviously 283 MW of natgas generation produces less greenhouse gases (GHGs) than 3,783 MW of natgas generation. So why did we need to export any gas generation in the first place since exports are highly subsidized by Ontario ratepayers to the benefit of the recipient jurisdiction?

This large amount of gas generation was likely exported because of the concern the IESO may have had with the risk of losing substantial wind generation under these circumstances (reference 1). Since most of the gas generation would be shutdown without exports the potential loss of 2,631 MW from wind would have had to be met from hydroelectric generation. With hydroelectric generation at this time already at a high 5,535 MW there may not have been enough extra MW and MWh available to cover the time period until the combined cycle gas turbine (CCGT) units could be fired up and dispatched to meet the wind shortfall. Ontario has only one quick start simple cycle gas turbine (SCGT) unit of 393 MW. Imports from other jurisdictions may not be available since wind failures affect large geographical areas and Quebec may have needed all its generation in house or had it already committed. The solution seems to have been to keep the CCGTs running at around their lowest dispatchable load so that they would always be available in case wind generation failed and the only way to do this was to feed an export market (reference 2). If sufficient extra MW and MWh of hydroelectric generation were available until the demand dropped there would be less or even no need to fire up the CCGTs. However, over the next five years or so several thousand MWs of additional wind will be coming onto the grid. With hydro generation limited the grid will see more use of the GHG emitting CCGTs (in MW and in MWh) and of exports (as in this snapshot) to maximize the use of the wind generation investment and minimize wind curtailment. The Ontario grid will depend even more on an export market and on reliable wind forecasting.
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Why wind power does not work in Ontario – and the solution

August 1, 2012

Why wind power does not work in Ontario – and the solution

By: Donald Jones, P.Eng. – retired nuclear industry engineer

This article, with minor differences, was published as an opinion piece in the Canadian Nuclear Society’s BULLETIN journal, 2012 June edition.

I haven’t noticed the price of Ontario’s electricity dropping despite an over supply of generation and a ten year low in north American natural gas prices. This is mainly because of the Ontario government’s misguided policy of promoting more and more wind generation on the grid under the protection of the Green Energy Act. Large amounts of intermittent wind skew the market leading to take-or-pay contracts (necessary to ensure capacity is built and always available when wind is absent) with the gas-fired generators and the need to export electricity at subsidized give away prices. No one would build merchant gas-fired generators in Ontario since they would be operating at low capacity factors and would price themselves out of the market.

Nuclear electricity provides around 60 percent of Ontario demand and hydro about 20 percent leaving 20 percent or so for the rest, that is, mostly inflexible natural gas and some unreliable wind under Ontario government authority contracts, with flexible coal coming in at times of peak demand.  Without wind on the grid gas would have a better chance of supplying all the intermediate and peaking load and see an increasing amount of steady operating hours with lower generation costs. More and more wind being added to the grid in these times of continuing low demand result in very low market prices, even negative prices during the frequent periods of surplus baseload generation (SBG) that is indicative of a poorly designed grid.  Since wind is completely unnecessary in the first place it makes little sense to provide expensive energy storage, even if this were technically and environmentally achievable. Read the rest of this entry »


Natural gas prices go lower and Ontario electricity prices go higher – 2012 April

April 23, 2012
I haven’t noticed the price of Ontario’s electricity dropping over the past few years despite the lowest ever natural gas prices. Blame the Ontario government’s misguided policy of promoting more and more wind generation on the grid under the protection of the Green Energy Act. Unreliable wind skews the market leading to high take-or-pay payments instead of low market prices going to the gas-fired generators and the need to export electricity at subsidized give away prices. No one would build merchant gas-fired generators in Ontario since they would be operating at low capacity factors and would price themselves out of the market. Nuclear electricity provides around 60 percent of Ontario demand and hydro about 20 percent leaving 20 percent or so for the rest, that is, natural gas and unreliable wind under Ontario Power Authority contracts, with coal coming in at peak loads. Without wind on the grid gas would have a better chance of supplying all the intermediate and peaking load and see more and steady operating hours giving lower generation prices. Of course the present low Ontario demand leading to frequent periods of surplus baseload generation, that are exacerbated by wind, also contributes to the mess the electricity market is in.
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No future for wind in Ontario – thestar.com

April 10, 2012

An article by Donald Jones in the Toronto Star, from March 2009, was an early indication of the problems integrating intermittent generation with Ontario’s baseload nuclear capacity

No future for wind in Ontario – thestar.com.

Although nuclear units can handle the daily and weekend changes in electricity demand, they have limited capability for the kind of frequent power-up and power-down requirements that would be needed for this support. Furthermore, hydroelectric plants may not always be available due to fluctuations in water supply and water management agreements.

Even without restrictions on nuclear and hydro, it makes little economic sense to run reliable suppliers of steady power, with high fixed costs and low operating costs, at reduced output to support the expensive, intermittent and varying output from wind farms.

So, with coal being phased out by 2014, natural gas-fired generation will have to be used to support wind. Due to the simultaneous demands of home heating and electricity generation in the winter, that may lead to gas shortages. So some of these plants may be dual fuelled with gas and oil, which is not a pleasant thought.

The Ontario government is putting too much faith in natural gas for electricity generation, as the United Kingdom did with its “dash for gas” from the North Sea in the 1990s when gas was cheap. Now the U.K. is in terrible shape with its gas running out and the threat of power shortages in the next decade.