[mwattsun]

The accident at Three Mile Island and the film "China Syndrome" turned the public against it in America. The prejudice still lingers. I was working as a reactor tech on a nuclear submarine shortly after and decide before I got out that there was no future in nuclear. I became a computer programmer instead. Alvin Toffler's book "The Third Wave" convinced me to do this.

[Lammy]

The saddest part of the TMI accident is that the entire thing could have been avoided if TMI had modified its cooling system with the lessons learned from an identical series of events that happened two years earlier at an identical Babcock&Wilcox BWR in Ohio, except Davis-Besse was operating at 9% power instead of at 100% like TMI in Pennsylvania in 1979: https://www.nrc.gov/docs/ML1920/ML19208C067.pdf#page=4

"On September 24, 1977, Davis Besse Nuclear Power Station Unit No. 1 experienced a depressurization when a pressurizer power relief valve failed in the open position. The Reactor Coolant System (RCS) pressure was reduced from 2255 psig to 875 psig in approximately twenty-one (21) minutes. At the beginning of this event, steam was being bypassed to the condenser and the reactor thermal power was at 263 MW, or 9.5%. Electricity was not being generated. The following systems malfunctioned during the transient:

a. Steam and Feedwater Rupture Control System (SFRCS).

b. Pressurizer Pilot Actuated Relief Valve.

c. No. 2 Steam Generator Auxiliary Feed Pump Turbine Governor"

"At approximately 21 minutes into the transient, the operators discovered that the pressurizer power relief valve was stuck open. Blowdown via this valve was stopped by closing the block valve, thus terminating the reactor vessel depressurization. The RCS pressure recovered to normal and cooldown of the system followed."

"The reason for the spurious 'half-trip' of the SFRCS has not yet been determined. An extensive investigation revealed several loose connections at terminal boards, but nothing conclusive. Investigation into the failure of the pressurizer pilot actuated relief valve revealed that a 'close' relay was missing from the control circuit. This missing relay would normally provide a 'seal-in' circuit which would hold the valve open until the pressure dropped to 2205 psig. Without the relay the power relief valve cycled open and closed each time the pressure of the RCS went above or below 2255 psig. The rapid cycling of the valve caused a failure of the pilot valve stem, and this failure caused the power relief valve to remain open."

[dctoedt]

Another ex-nuke here — when I got out and went to law school, coincidentally right after Three Mile Island, my dad (neither a lawyer nor an engineer) tried to convince me that I should specialize in nuclear-energy law because I'd have a built-in advantage. I politely explained why I thought that would be a dead end, and that turned out to be correct.

[mwattsun]

Working in nuclear under normal operations is boring anyway and consists mostly of watching gauges and other indicators. At least on the submarine we'd scram the reactor and run drills. I'm sure civilian nuclear is less exciting than this. I had one buddy who did it for a career, but just one that I know of.

[dctoedt]

> and consists mostly of watching gauges and other indicators

And logs. You forgot taking logs* — or is that done automatically these days? It's been decades since I've been in a nuclear plant, so I have no idea.

* That is, recording readings of various indicators.

[mwattsun]

They're probably recorded automatically but logs are still taken as way to ensure human eyes are on the indicators, like security guards have to scan a waystation point to prove they were there. I haven't been in a plant for over three decades so I don't know either.

One thing I carried with me through life was to "always trust your indicators." It's too easy to look at an anomaly and conclude the gauge is broken.