"What is the mechanism that increases risk for MOV-sourced fires in this arrangement?"
I wondered the same thing, and failed to find a satisfying explanation.
I can find plenty of reports of MOV fires, especially in situations where there's a persistent over-voltage, e.g. a 120 V site actually having closer to 240 V due to a floating neutral. But I don't see how chained MOVs make that worse in general. This blog post has some nice photos:
It took me a while to realise that you were responding to the article, not a comment here.
You're right in correcting the article, but I'd like to add that for probably around a decade, Erlang had 'sender punishment', which is what 'IsTom' who replied to you is probably talking about.
Ulf Wiger referred to sender_punishment as "a form of backpressure" (Erlang-questions mailing list, January 2011). 'sender punishment' was removed around 2018, in ad72a944c/OTP14667. I haven't read the whole discussion carefully, but it seems to be roughly "it wasn't clear that sender punishment solved more problems than it caused, and now that most machines are multi-core, that balance is tipped even more in favour of not having 'sender punishment'".
> All the designs I know of have a pumped (active) cooling loop for the reactor, then a secondary loop where the coolant (typically water) evaporates and drives a turbine, [...] You don't want potentially radioactive water to interact with your turbine directly, makes it a nightmare to maintain
A "Boiling Water Reactor" (BWR) has the reactor and the turbine on the same cooling loop. The radioactivity in the water going through the turbine is not a "nightmare", it is a manageable trade-off.
Some major currently-operating BWRs are Leibstadt (Switzerland, 1.2 GWe), Oskarshamn (Sweden, 1.4 GW) and several dozen in the USA. Germany also had some, they were shut down a few years ago (e.g. Grundremmingen).
I wondered the same thing, and failed to find a satisfying explanation.
I can find plenty of reports of MOV fires, especially in situations where there's a persistent over-voltage, e.g. a 120 V site actually having closer to 240 V due to a floating neutral. But I don't see how chained MOVs make that worse in general. This blog post has some nice photos:
https://www.electrical-forensics.com/SurgeSuppressors/SurgeS...