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Comment by velodrome | Hacker News Reader

Too bad this article mentions nothing about the future of LFTR reactors (Thorium).

Thorium reactors have too much going on inside the reactor, and a radioactive chemical plant outside it. The history of nuclear reactors indicates that plants with anything complex going on inside run into problems. Sodium reactors have sodium fires. Helium reactors leak. Pebble bed reactors jam. Boring old water reactors are about all that can be made to work for decades.

Running a radioactive chemical plant usually results in a toxic waste site. All three US reprocessing plants are now major toxic waste sites.

  Boring old water reactors are about all that can be made to work for decades.

A sodium-cooled breeder reactor worked continuously for 30 years and survived a (planned) hard power-down of all external cooling apparatus in 1986[0] to demonstrate its design safety.

After being shut down by the Clinton administration in 1994 (as was its follow-on IFR program), disassembly showed no meaningful wear or damage to its hardware.

"In controlled testing in 1986, with the EBR-II reactor running at full power and the emergency shutdown systems disabled, the reactor's supply of electricity was intentionally turned off, causing the coolant pumps to stop. This is a worse scenario than what happened in the Fukushima Nuclear Disaster. (At Fukushima, which began operation in 1971, the emergency shutdown system turned off the reactor as soon as it detected the earthquake. However the tsunami destroyed the electric generators powering the coolant pumps, which needed to continue running after the reactor shutdown. Subsequently, the core overheated and meltdown occurred.) EBR-II, in contrast, handled the event without creating a dangerous situation. EBR-II had a negative thermal coefficient of reactivity that shut down the reactor when the temperature increased due to loss of the coolant pumps; the time required to heat the large pool of sodium surrounding the reactor provided a sufficient time buffer for the passive decay heat removal system to prevent the EBR-II reactor from melting down. The safe shutdown of the EBR-II relied only on the laws of physics and did not require operator or control system intervention."

[0] https://en.wikipedia.org/wiki/Experimental_Breeder_Reactor_I...

This reactor was 1/50th the scale of a typical power reactor. The radiation, thermal-hydraulic, and chemical environment of a full-scale reactor is different. Different stress corrosion interactions, severe oscillating stresses due to thermal-hydraulic fluctuations at assembly outlets... The operational record of such reactors hardly supports them as foolproof or economical versus the best modern water reactors.

Researching thorium all the way to production will cost a lot of money. For the same money, we could do a lot of research into new storage ideas and solar thermal, which thus far has been disappointing in production, but does make storage easier.

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