Ancient Nuclear Plant Computer Finds New Home In Bletchley Museum

A man removing a module from a 1960s computer

Although technology keeps advancing every year, safety-critical systems in factories and power plants typically stay with the technology that was available when they were built, in the spirit of “don’t fix it if it ain’t broke”. When it comes to safety, there are probably few systems more critical than nuclear power plants, and as a result one power station in Dungeness, in the south-east of England, was controlled by the same Ferranti Argus 500 computer from the early 1970s until the reactor was shut down in 2018.

The national Museum of Computing in Bletchley was lucky enough to be allowed to scavenge the old computer from the decommissioned plant, and volunteers at the museum have managed to get it running again in its new home. They describe the process in the video embedded below, and demonstrate a few features of this rather unique piece of 1970s technology.

The computer consists of several large cabinets that house enormous PCBs full of diode-transistor logic (DTL) chips, made by Ferranti itself. It comes with 32 kilo-words, or 96 kilobytes, of magnetic core memory, and was designed to run programs stored on punched tape. However, the paper tape reader was removed at some point in the computer’s life and replaced with a PC-based system that emulates the tape reader’s output through its parallel port. This was probably sometime during the 1990s, judging from the fact that the runs OS/2.

Setting up the computer in its new home was complicated by the fact that hundred of cables had to be disconnected in order to move the system out of the power plant. With the help of decades-old documentation, and the experience of one volunteer who used to be a Ferranti engineer, they eventually got it into a state where it could run programs again.

Ultimately, the Argus 500 will be turned into a live exhibit that will simulate a power station alongside another computer that was rescued from a different nuclear plant. Depending on the availability of some parts that are still missing, this might happen later this year, or perhaps next year. In any case, the museum already has a collection that’s well worth visiting if you’re in the area. The story of how they rescued a neglected IBM 360 also makes for fascinating reading.

Thanks for the tip, [Dunryc]!

20 thoughts on “Ancient Nuclear Plant Computer Finds New Home In Bletchley Museum

  1. I was wondering where the German 360 ended up. The story of its purchase, rescue and transport was quite a saga. The last I heard, it was a guest in a decommissioned bunker which had been converted to a server farm. Nice to hear it has found a home among other elderly computing systems, where it can be admired by us geeks. Will they be selling copies of “The Mythical Man-month” in the gift shop (if you haven’t read it, it’s worth the read, though, IMHO, it is overpriced)?.

  2. worked with the next generation Ferranti Argus 700 at Hunterston, another Nuclear Station. No such thing as a video terminal. Everything was on teletype with wide body fanfold printer paper. Every typo there for posterity. Entire rainforests consumed feeding the teletype….

  3. I’m VERY reliably informed that one of these was involved in an incident at a power plant. What happend is rainwater leaked through the roof into the computer causing it to begin malfunctioning, at first it caused weird readings but as it progressed the computer began removing the control rods from the reactor causing the power to begin rising, the rate of rise detectors (in a different part of the plant) detected an excessive rate of power increase and SCRAM’ed th reactor.

  4. In a previous career, we had a couple of nuclear power plants as customers that used 20+ year old (at that time) computers that had some of our products inside. We were specifically told we could do nothing to the board that would result in any changes in the weight profile, since the entire Core Protection Calculator had been seismically qualified, and any change would require requalification of the _entire system_. There were a couple of design flaws in our boards that had been corrected by Engineering Orders with a trace cut or two and a couple of jumpers, and even installing those was a no-go, so they would have to send the boards back for repair occasionally for replacement of parts that were getting electrically overstressed.

    So, there’s a reason the old hardware stays in place, and in its old configuration. Oviously the

  5. Very interesting information on thsi page.

    I did repair work on the CPUs and core memories of an ARGUS 500 system from 1989 until 1992. The 500, in a duplicated system, was being used at the Air Traffic Control Centre in building 237 at Sydney Airport for message switching by the then Civil Aviation Authority as part of Australia’s air traffic control system.

    I was surprised to hear one was used until 2018 to control a nuclear power station.

    In Australia I believe they were also used by the Melbourne Metropolitan Board of Works to control their sewage system, and another was used for surface warfare simulation by the Royal Australian Navy.

    The place I worked at, the “Automatic Message Switching Centre” (AMSC) did repair work for both those other ARGUS systems.

    I believe one was also installed onboard the ‘Queen Mary’ ocean liner.

    1. There was a Ferranti Argus on the QE2 ….Queen Elizabeth 2nd … complete with Ampex reel-to-reel tape transports. Us engineers prayed for a breakdown when the ship was in the Caribbean, and the dream came true for some. What did I get? A call to Southampton and a cross channel work trip to Le Havrre!

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.