Comment on Power Companies Are Using AI To Build Nuclear Power Plants

• Assassassin@lemmy.dbzer0.com ⁨1⁩ ⁨day⁩ ago

  Per the IAEA report on Chernobyl, page 4:

  The control rods and the safety rods of an RBMK reactor are inserted into the reactor core from above, except for 24 shortened rods which are inserted upwards and which are used for flattening the power distribution. A graphite rod termed a 'displaced is attached to each end of the length of absorber of each rod, except for twelve rods that are used in automatic control. The lower displacer prevents coolant water from entering the space vacated as the rod is withdrawn, thus augmenting the reactivity worth of the rod. The graphite displacer of each rod of all RBMK reactors was, at the time of the accident, connected to its rod via a ‘telescope’, with a water filled space of 1.25 m separating the displacer and the absorbing rod (see Fig. 1). The dimensions of rod and displacer were such that when the rod was fully extracted the displacer sat centrally within the fuelled region of the core with 1.25 m of water at either end. On receipt of a scram signal causing a fully withdrawn rod to fall, the displacement of water from the lower part of the channel as the rod moved down- wards from its upper limit stop position caused a local insertion of positive reactivity in the lower part of the core. The magnitude of this ‘positive scram’ effect depended on the spatial distribution of the power density and the operating regime of the reactor.

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  • kameecoding@lemmy.world ⁨1⁩ ⁨day⁩ ago

    Yes, those “tips” were like 2 meters long, basically, instead of just being breaks, the rods had dual function and also acted as accelerators, when they pressed az-5, they didn’t enter first, they were already in the core, but something happened which I don’t understand where once az-5 was pressed as those tips started lowering an imbalance formed and they they got stuck and it resulted in a runaway reaction, I think at least that’s accepted as the most likely theory as IIRC they don’t exactly know what happened.

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    • BussyCat@lemmy.world ⁨1⁩ ⁨day⁩ ago

      I could be mistaken but wasn’t the issue that when the rods were fully withdrawn the graphite was also partially withdrawn so when they scrammed the first thing that happened was an insertion of positive reactivity from the graphite which was enough positive reactivity to burn up all the xenon which then caused the reactor to go prompt critical?

      Like the presence of the graphite wasn’t that bad but it combined with a lack of interlocks and improperly trained operators was the big problem and of course trying to start up at the peak of a xenon transient is never ideal

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