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Nobody claims 100% availability. Doesn't change that nuclear is by far the most reliable electricity generator. The US nuclear fleet has had capacity factors

Nobody claims 100% availability. Doesn't change that nuclear is by far the most reliable electricity generator. The US nuclear fleet has had capacity factors in the 95% range for ages now. And the 5% tend to be planned maintenance/fueling. Not only are the times of unavailablilty very rare and usually plannable, they are also uncorrelated. Seasons, day/night cycles and even large scale weather patterns are highly correlated.

Retric 2y ago
Depends on the timeframe. Nuclear is among the least dependable generation sources from a long term capacity standpoint, with multiple incidents taking generation off for long periods. 3 mile island wasn’t a big deal from a health and safety standpoint, but at 4 AM TMI-2 went offline with zero warning and never came back. Similarly you can’t trust timelines for when exactly new generation will come online. Less severe incidents don’t necessarily make the news, but losing 1.3 GW at some random period for weeks or months isn’t particularly uncommon. Sure major incidents are “rare,” but there’s not actually that many nuclear power plants ever constructed.
- mpweiher 2y ago
  Completely incorrect. Nuclear has the highest reliability of all generation sources, with for example the largest fleet of reactors, the US fleet, consistently coming in at around 95% capacity factor. Most of the remaining 5% is scheduled outages for maintenance and refueling. And both the rare scheduled as well as the even rarer unscheduled outages tend to be uncorrelated. Well, unless radiophobia grips a country and they decide to shut everything down. Trust renewbros to always use a single example to bolster their claims.
  - Retric 2y ago
    Examples are plentiful, read up on why Foreign material exclusion (FME) is such a major concern. Months of completely unplanned outage, 10’s millions in damage and even more in lost production all from a minor mistake. Short term capacity factor is not the same as reliability, the grid needs power every day not some average over a year. Add some turbines and a given dams capacity factor drops but it becomes more valuable due to the added flexibility and redundancies. Lifetime capacity factors of US reactors are a long way from 95% often in the low 80% or below that’s not because the grid doesn’t want their power but because nuclear is unreliable over the long term. 96.04% in 2017, lifetime 78.07% (unreliable). https://en.wikipedia.org/wiki/Browns_Ferry_Nuclear_Plant https://en.wikipedia.org/wiki/Browns_Ferry_Nuclear_Plant 95.7% in 2017 vs 80.25% lifetime (unreliable). https://en.wikipedia.org/wiki/Beaver_Valley_Nuclear_Power_Station https://en.wikipedia.org/wiki/Beaver_Valley_Nuclear_Power_St... And before you think 2017 just had unusually high demand, nope 79.36% capacity factor in 2017. https://en.wikipedia.org/wiki/Arkansas_Nuclear_One https://en.wikipedia.org/wiki/Arkansas_Nuclear_One That’s just another unpleasant reality when trying to actually use nuclear as a major energy source.
    - mpweiher 2y ago
      > Short term capacity factor is not the same as reliability, Er, capacity factor and reliability are not the same thing, that is true. But not in the way you seem to think. Capacity factor is more stringent than simple reliability, as it also takes into account planned outages and even power reductions due to external circumstances, for example when nuclear output in Finnland was throttled to compensate for the over-production problems they had with their hydro last year. Please do read up: https://en.wikipedia.org/wiki/Capacity_factor https://en.wikipedia.org/wiki/Capacity_factor And you do need to make up your mind whether you think long term or short term is important, because you are contradicting yourself on that. Capacity factors are usually given for a year, and in recent years, the capacity factors for nuclear in the US have been in the 95% range for a while, though recently dropped to "just" 93%. What the capacity factor was 30 years ago isn't really relevant. The idea that 93%-96% capacity factors somehow make nuclear power "unreliable" is ... "interesting". If you find a more reliable electricity source, do present it here. https://en.wikipedia.org/wiki/Capacity_factor#/media/File:US_EIA_monthly_capacity_factors_2011-2013.png https://en.wikipedia.org/wiki/Capacity_factor#/media/File:US...
      - Retric 2y ago
        > Capacity factors are usually given for a year That inherently misrepresents nuclear when the fueling cycle lasts longer than a year and maintenance cycles extend across decades. But again reliability is the ability to provide a service. A full multi week outage can’t be patched over via batteries, you need redundancy. Suppose your an island nation considering looking to get 3GW of nuclear. You’d like the most efficient option of really huge 1.5 GW reactors but if any of them is offline you’re already at 50% output. It’s going to happen, and the grid needs to be able to deal with it, in practice it would need to be able to deal with both being offline for weeks.. > The idea that 93%-96% capacity factors somehow make nuclear power "unreliable" is ... "interesting". Even a 95% capacity factor over a year can represent near perfect uptime OR include a random 2 week outage with zero notice during absolutely peak seasonal demand. But again lifetime averages are often in the 80% range and that’s not from fueling cycles alone. Many multi month outages are guaranteed to happen during a plants lifespan requiring further redundancy based around the assumption that nuclear is unavoidable.

Retric 2y ago

Depends on the timeframe. Nuclear is among the least dependable generation sources from a long term capacity standpoint, with multiple incidents taking generation off for long periods. 3 mile island wasn’t a big deal from a health and safety standpoint, but at 4 AM TMI-2 went offline with zero warning and never came back. Similarly you can’t trust timelines for when exactly new generation will come online. Less severe incidents don’t necessarily make the news, but losing 1.3 GW at some random period for weeks or months isn’t particularly uncommon. Sure major incidents are “rare,” but there’s not actually that many nuclear power plants ever constructed.

mpweiher 2y ago
Completely incorrect. Nuclear has the highest reliability of all generation sources, with for example the largest fleet of reactors, the US fleet, consistently coming in at around 95% capacity factor. Most of the remaining 5% is scheduled outages for maintenance and refueling. And both the rare scheduled as well as the even rarer unscheduled outages tend to be uncorrelated. Well, unless radiophobia grips a country and they decide to shut everything down. Trust renewbros to always use a single example to bolster their claims.
- Retric 2y ago
  Examples are plentiful, read up on why Foreign material exclusion (FME) is such a major concern. Months of completely unplanned outage, 10’s millions in damage and even more in lost production all from a minor mistake. Short term capacity factor is not the same as reliability, the grid needs power every day not some average over a year. Add some turbines and a given dams capacity factor drops but it becomes more valuable due to the added flexibility and redundancies. Lifetime capacity factors of US reactors are a long way from 95% often in the low 80% or below that’s not because the grid doesn’t want their power but because nuclear is unreliable over the long term. 96.04% in 2017, lifetime 78.07% (unreliable). https://en.wikipedia.org/wiki/Browns_Ferry_Nuclear_Plant https://en.wikipedia.org/wiki/Browns_Ferry_Nuclear_Plant 95.7% in 2017 vs 80.25% lifetime (unreliable). https://en.wikipedia.org/wiki/Beaver_Valley_Nuclear_Power_Station https://en.wikipedia.org/wiki/Beaver_Valley_Nuclear_Power_St... And before you think 2017 just had unusually high demand, nope 79.36% capacity factor in 2017. https://en.wikipedia.org/wiki/Arkansas_Nuclear_One https://en.wikipedia.org/wiki/Arkansas_Nuclear_One That’s just another unpleasant reality when trying to actually use nuclear as a major energy source.
  - mpweiher 2y ago
    > Short term capacity factor is not the same as reliability, Er, capacity factor and reliability are not the same thing, that is true. But not in the way you seem to think. Capacity factor is more stringent than simple reliability, as it also takes into account planned outages and even power reductions due to external circumstances, for example when nuclear output in Finnland was throttled to compensate for the over-production problems they had with their hydro last year. Please do read up: https://en.wikipedia.org/wiki/Capacity_factor https://en.wikipedia.org/wiki/Capacity_factor And you do need to make up your mind whether you think long term or short term is important, because you are contradicting yourself on that. Capacity factors are usually given for a year, and in recent years, the capacity factors for nuclear in the US have been in the 95% range for a while, though recently dropped to "just" 93%. What the capacity factor was 30 years ago isn't really relevant. The idea that 93%-96% capacity factors somehow make nuclear power "unreliable" is ... "interesting". If you find a more reliable electricity source, do present it here. https://en.wikipedia.org/wiki/Capacity_factor#/media/File:US_EIA_monthly_capacity_factors_2011-2013.png https://en.wikipedia.org/wiki/Capacity_factor#/media/File:US...
    - Retric 2y ago
      > Capacity factors are usually given for a year That inherently misrepresents nuclear when the fueling cycle lasts longer than a year and maintenance cycles extend across decades. But again reliability is the ability to provide a service. A full multi week outage can’t be patched over via batteries, you need redundancy. Suppose your an island nation considering looking to get 3GW of nuclear. You’d like the most efficient option of really huge 1.5 GW reactors but if any of them is offline you’re already at 50% output. It’s going to happen, and the grid needs to be able to deal with it, in practice it would need to be able to deal with both being offline for weeks.. > The idea that 93%-96% capacity factors somehow make nuclear power "unreliable" is ... "interesting". Even a 95% capacity factor over a year can represent near perfect uptime OR include a random 2 week outage with zero notice during absolutely peak seasonal demand. But again lifetime averages are often in the 80% range and that’s not from fueling cycles alone. Many multi month outages are guaranteed to happen during a plants lifespan requiring further redundancy based around the assumption that nuclear is unavoidable.