SKALA - ChNPP computer, history of creation

Today marks the 28th anniversary of the Chernobyl disaster. Many articles have been written on this topic, many theories have been put forward about the causes of the explosion, many investigations and conclusions have been made. In this article I will try not to touch the very topic of the explosion and the subsequent catastrophe, but I will tell you about the history of the creation of the computer that regulated the work of the station - about the SKALA system. Who cares - welcome under cat.

As we all know, a reactor is a device, although not too complicated, but it requires in its management that multiple factors are taken into account and a sufficiently rapid response is achieved. Therefore, the introduction of a computer into the reactor control system was obvious. By the end of the 60s, the most promising computer in the USSR was a 24-bit semiconductor VNIIEM-3, developed in the same-name enterprise . Strictly speaking, VNIIEM-3 was classified as UVM - control computer, i.e. a specialized computer designed to process a large number of analog signals and to issue on the basis of their analysis the corresponding control signals. Under the guidance of Dr. of Sc. B. M. Kagan, on the basis of this UVM, information control systems were set up at the chemical production in Angarsk and at the metallurgical plant in Galati (Romania). An important role in the launch of these systems was played by V. N. Stepanov, I. A. Zhigunov and I. S. Koltypin.

For further use in the production of UVM "VNIIEM-3" has undergone significant modernization, after which it became known as V-3M. This machine has been very successful in terms of both architecture and design. It used unified information transmission channels, which made it easy to add new devices to the machine; a developed system of commands for working with full words and half words; advanced interrupt system; multi-machine operation; control and error correction in a four-port ferrite storage device. Great improvements were made to the machine design - for the first time in the country, instead of soldered mounting, wrap mounting was used in the panels, printed wiring was used in the boards, and a palladized connector with double contacting was proposed for the boards. In the B-3M computer, replaceable printed circuit boards were securely fastened in the panel and were well ventilated. Automatic change of supply voltages was used during maintenance. All this ensured a great hardware reliability of a computer.

The B-3M car debuted in the mid-60s on the initiative of A. Iosif'yan in the space industry. UVM was used to decipher the data stream from a meteorological satellite. The machine replaced complex manual decoding of parameters and, by performing frame filtering, provided reliable information even when 80–90% of the frames were distorted by interference. At the same time, the result was printed almost immediately after the flight of the satellite over Moscow.
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So, at the end of the 60s, when the question arose about the development of the RBMK reactor control system (which was installed, including at the Chernobyl nuclear power plant), the choice of ministries obviously fell on the BVM-3M as the prototype of the future system. The work was entrusted to VNIIEM and at the beginning of the 70s the complex automation system of the Leningrad NPP Scala was developed by the team of the 38th department transferred to VNIIEM from VNIIElektroprivod under the leadership of Yu. D. Profranesov. The serial production of the Scala systems for NPPs with RBMK reactors began at IO VNIIEM, V. I. Adasko, M. Ya. Tanaev, A. D. Vorobev, I. A. Karasev, A. M. Pryadkin actively participated in it. N. D. Fedchenko.

Software for SKALA was developed in the same VNIIEM under the leadership of VF Tkach. It should be noted that the software was developed based on the concept of “virtual machines” - isolated software environments, the so-called "Sandboxes", which minimized the spread of errors between different subsystems.

The name "SCALA" is so stuck that it is still used to name the next generation of control systems for RBMK type reactors. Read more about the new systems here .

I would like to say a few words about the direct participation of the SCALA complex in the development of the accident 28 years ago. Despite the many versions of this accident itself, none of them indicated that the cause or aggravation of the situation was a malfunction of "SKAL". Which once again confirms that from the point of view of reliability this complex at that time was deservedly considered the best. The only way in which SCALA could have influenced the course of events is the speed at which calculations were performed - if the data on the reactor were processed faster, then the consequences would be different. But, this remark in no way calls into question the reliability of the system.

A small bonus for those who read to the end. The archive with the emulator program of the RBMK reactor control console (DOS_TOP.zip) is available at this link . A DOSbox is required to run (available from the same link). Quick Start Guide:

1. Unpack the archive where you want
2. Install and run DOSBox
3. In the DOSBox console, we write “mount DD: \ reactor”, where D: \ reactor should be replaced with the path to the folder where you unpacked the archive. Execute the command.
4. In the console DOSBox enter D :, run
5. We enter top, we execute
6. Trying to control the reactor

Thanks to habrauser there were several more emulators, all sorts of difficulties. Here is a list:

• www.atarimania.com/game-atari-400-800-xl-xe-scram_4543.html - from the haprayuser valplo
• esa21.kennesaw.edu/activities/nukeenergy/nuke.htm - from Atakua habrauser

New emulators are available via the same link. Those that have the word DOS in the name, require this DOS to run, you can use DOSBox. I also advise you to watch the BWR.exe emulator - it contains tutorials, though in English.
Photos are taken from here , for them a special thanks to IrinaInina Habrawer