this post was submitted on 17 May 2024
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Discussion of climate, how it is changing, activism around that, the politics, and the energy systems change we need in order to stabilize things.

As a starting point, the burning of fossil fuels, and to a lesser extent deforestation and release of methane are responsible for the warming in recent decades: Graph of temperature as observed with significant warming, and simulated without added greenhouse gases and other anthropogentic changes, which shows no significant warming

How much each change to the atmosphere has warmed the world: IPCC AR6 Figure 2 - Thee bar charts: first chart: how much each gas has warmed the world. About 1C of total warming. Second chart: about 1.5C of total warming from well-mixed greenhouse gases, offset by 0.4C of cooling from aerosols and negligible influence from changes to solar output, volcanoes, and internal variability. Third chart: about 1.25C of warming from CO2, 0.5C from methane, and a bunch more in small quantities from other gases. About 0.5C of cooling with large error bars from SO2.

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Five Things the “Nuclear Bros” Don’t Want You to Know About Small Modular Reactors (blog.ucsusa.org)
submitted 6 months ago* (last edited 6 months ago) by [email protected] to c/[email protected]
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A realistic understanding of their costs and risks is critical.

What are SMRs?

  1. SMRs are not more economical than large reactors.

  2. SMRs are not generally safer or more secure than large light-water reactors.

  3. SMRs will not reduce the problem of what to do with radioactive waste.

  4. SMRs cannot be counted on to provide reliable and resilient off-the-grid power for facilities, such as data centers, bitcoin mining, hydrogen or petrochemical production.

  5. SMRs do not use fuel more efficiently than large reactors.

[Edit: If people have links that contradict any the above, could you please share in the comment section?]

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[–] [email protected] 9 points 6 months ago* (last edited 6 months ago)

I think the EU Commission has done a fairly good job of listing the pros and contras of small modular reactors:

https://energy.ec.europa.eu/topics/nuclear-energy/small-modular-reactors/small-modular-reactors-explained_en

They have some advantages over conventional (large) reactors in the following areas:

  • if they are serially manufactured without design chances, manufacturing is more efficient than big unique projects
  • you can choose a site with less cooling water
  • you can choose a site where a fossil-burning plant used to be (grid elements for a power plant are present) but a renewable power plant may not be feasible
  • some of them can be safer, due to a higher ratio of coolant per fuel, and a lower need for active cooling*

Explanation: even a shut down NPP needs cooling, but bigger ones need non-trivial amounts of energy, for example the 5700 MW plant in Zaporizhya in the middle of a war zone needs about 50 MW of power just to safely stay offline, which is why people have been fairly concerned about it. For comparison, a 300 MW micro-reactor brought to its lowest possible power level might be safe without external energy, or a minimal amount of external energy (which could be supplied by an off-the-shelf diesel generator available to every rescue department).

The overview of the Commission mentions:

SMRs have passive (inherent) safety systems, with a simpler design, a reactor core with lower core power and larger fractions of coolant. These altogether increase significantly the time allowed for operators to react in case of incidents or accidents.

I don't think they will offer economical advantages over renewable power. Some amont of SMRs might however be called for to have a long-term steerable component in the power grid.