What is xenon poisoning in nuclear reactors, for that matter what are neutron poisons?

For the most part, every isotope is a neutron poison unless it is a neutron source, some isotopes like Xenon-135 just happen to have massive absorption cross sections making them very strong neutron poisons.

[@fieryweasel]

For those playing along at home, the 135-Xe half-life is a little over 9 hours, and reactor equilibrium after changing power levels/neutron flux is between 40 and 50 hours. Most of the 135-Xe in a reactor isn't directly created as a fission product; that only happens about .3% of the time. Most of it is created as a result of decays from 135-Te (t½ 19 seconds) and 135-I (t½ ~7 hours). All told, 135-Xe is created as a result of about 6% of fissions.

[@rdspam]

Thanks for the accurate update. I wondered where 14 hours came from.

[@christopherleubner6633]

The xenon pit explained in a minute. That's why you wait about 48 hours before restarting a stopped reactor. The worst that could happen is that the xenon burns up and the reactor is suddnly in a prompt supercritical condition. This is exactly what happened when Chernobyl blew up, the reactor went from almost zero to over 10GW in 30 seconds.😢

[@onefor2]

The Reactor Power production didnt spike until AZ-5 was pressed (it was pressed because it was part of the safety test, thats why)

[@Mineratron]

@@onefor2that’s not entirely correct… the statement above is. The attempt to restart the reactor after it stalled was a known cardinal sin in reactor physics even back then. The rest are just another series of holes in the Swiss cheese leading up to the explosion of the core.

[@Walter-Weiss]

Nah just press Az5 what could go wrong?

[@rayrays96]

Agree

[@dishadidi3000]

Nice

[@zachfernandez1257]

Xenon is also a fuel for ion propulsion so when your reactor is off you use the xenon to power the thrusters 😮

[@NorthernChev]

I can’t tell you how much it bothers me to see people of influence running around with extremely dangerous software like TikTok on their phones…

[@bulgingbattery2050]

Chernobyl

[@robertbhayes5039]

Red herring

[@breakfast7595]

@@robertbhayes5039 How though? Wasn't the buildup of Xenon a contributing factor to the Chernobyl disaster?