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In a previous career I was a Nuclear Reactor Operator for the US Navy. The acronym/story we were told regarding SCRAM was “Super Critical Reactor Axe Man”; as

In a previous career I was a Nuclear Reactor Operator for the US Navy. The acronym/story we were told regarding SCRAM was “Super Critical Reactor Axe Man”; as in the guy who would cut the rope to drop the control devices into the fission pile if they detected its reactivity going TOO super critical. Interestingly this usage doesn’t seem well known outside of those circles. It is/was, however, directly printed in rather old publications I used (60s perhaps?).

AnimalMuppet 6y ago
Three questions: Was there really a rope, and you really cut it with an axe? What did this do to the life expectancy of the ax operator? Does any of this have anything to do with your HN username? If there's a story, would you tell?
- ggm 6y ago
  According to Rhodes A-Bomb book, for the original Pile in Chicago there was a rope, and there was a guy with an axe. There was a backup to the backup: people with a solution of something (borate?) to pour into the pile to soak up surplus neutrons. This was a really bad thing to do, for the future use of the pile: the carbon would be soaked, useless, the reactivity of the pile would be next to impossible to get back without completely re-constructing it so the Scram by lowering rods, was the preference, and was done by a counter for accellerated scaling aside from the guy with the axe after a while.
- CobaltFire 6y ago
  As mentioned in the other reply, this was under some bleachers and yes there was a rope and a guy with an axe. No idea what it did to his lifespan. For my username: I actually started using this name before I was involved in nuclear power, and that’s the first time that’s been asked!
- brandmeyer 6y ago
  ESR's outline is more-or-less correct. Electric current is required to maintain a magnetic field. When the field collapses some mechanical device takes over using stored energy (springs and/or gravity) Here's a practical example to give some more context to the idea: https://patents.google.com/patent/US3721462A/en https://patents.google.com/patent/US3721462A/en https://patents.google.com/patent/US8811561B2/en https://patents.google.com/patent/US8811561B2/en
dctoedt 6y ago
> The acronym/story we were told regarding SCRAM was “Super Critical Reactor Axe Man” Another ex-Navy nuke here. When I went through nuclear power school (the West Coast one at Mare Island) in the 1970s, the version we heard was "Safety Control Rod Axe Man."

AnimalMuppet 6y ago

Three questions: Was there really a rope, and you really cut it with an axe? What did this do to the life expectancy of the ax operator? Does any of this have anything to do with your HN username? If there's a story, would you tell?

ggm 6y ago
According to Rhodes A-Bomb book, for the original Pile in Chicago there was a rope, and there was a guy with an axe. There was a backup to the backup: people with a solution of something (borate?) to pour into the pile to soak up surplus neutrons. This was a really bad thing to do, for the future use of the pile: the carbon would be soaked, useless, the reactivity of the pile would be next to impossible to get back without completely re-constructing it so the Scram by lowering rods, was the preference, and was done by a counter for accellerated scaling aside from the guy with the axe after a while.
CobaltFire 6y ago
As mentioned in the other reply, this was under some bleachers and yes there was a rope and a guy with an axe. No idea what it did to his lifespan. For my username: I actually started using this name before I was involved in nuclear power, and that’s the first time that’s been asked!
brandmeyer 6y ago
ESR's outline is more-or-less correct. Electric current is required to maintain a magnetic field. When the field collapses some mechanical device takes over using stored energy (springs and/or gravity) Here's a practical example to give some more context to the idea: https://patents.google.com/patent/US3721462A/en https://patents.google.com/patent/US3721462A/en https://patents.google.com/patent/US8811561B2/en https://patents.google.com/patent/US8811561B2/en

dctoedt 6y ago

> The acronym/story we were told regarding SCRAM was “Super Critical Reactor Axe Man” Another ex-Navy nuke here. When I went through nuclear power school (the West Coast one at Mare Island) in the 1970s, the version we heard was "Safety Control Rod Axe Man."