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Video Transcript: Chernobyl Test Events

[Time Stamp: 00:00] The following is from a Soviet television report on the Chernobyl 4 accident:

[Time Stamp: 00:10] 25th of April: The reactor is working at nominal power, 3200 megawatts.

[Time Stamp: 00:16] One o’clock in the morning. The staff have begun to take out the unit for maintenance.

[Time Stamp: 00:24] Power down to 2600 megawatts. Turbine Generator #7 has been switched off.

[Time Stamp: 00:30] 0 0 0

[Time Stamp: 00:31] In accordance with the test program, the maximum design accident system has been switched off. This is one of the main mistakes made.

[Time Stamp: 00:43] The taking of this unit out of operation has been held up.

[Time Stamp: 00:47] In violation of the regulations, the unit continues to operate without proper protection.

[Time Stamp: 00:54] Power is down to 1600 megawatts, at which the test will take place.

[Time Stamp: 00:58] The local automatic control system has been switched off.

[Time Stamp: 01:02] But because of a lack of technical qualification of the staff working there, the power of the reactor could not be stabilized at the planned level.

[Time Stamp: 01:09] The power has dropped down to 30 megawatts.

[Time Stamp: 01:11] The reactor is in a very difficult to control situation.

[Time Stamp: 01:15] The unit is working in a fluctuating way.

[Time Stamp: 01:19] You have poisoning of the core. You should shut down the reactor.

[Time Stamp: 01:24] One should only be able to work on the reactor again in 24 hours.

[Time Stamp: 01:27] But this means that the testing would have to be broken off, so the staff take the decision to in fact continue.

[Time Stamp: 01:33] The emergency system for the steam system means that you can’t work under stable conditions and the staff once again violated the regulations to switch off that system.

[Time Stamp: 01:46] Power is not sufficient for the testing.

[Time Stamp: 01:47] 26th of April at 1 o’clock in the morning.

[Time Stamp: 01:51] By raising the control rods, the staff tried to increase the power of the reactor.

[Time Stamp: 01:56] The power is stabilized at a level of 200 megawatts, at the cost of raising practically all the control rods out of the core, although the regulations require that the reactor be shutdown under such a situation.

[Time Stamp: 02:07] This is the worst mistake the staff made.

[Time Stamp: 02:09] They lost control of the reactor.

[Time Stamp: 02:12] In addition to the six circulating pumps which would be working, two more in-reserve pumps have switched on.

[Time Stamp: 02:18] This is a mistake by the staff.

[Time Stamp: 02:20] This means that you’ll get a random increase in power.

[Time Stamp: 02:22] In order to make it possible to have a second test, the staff decide to block one more emergency system.

[Time Stamp: 02:31] This is the steam into the turbine generator signal which is switched off.

[Time Stamp: 02:37] One o’clock…40 seconds: #8 steam generator is in fact switched on.

[Time Stamp: 02:44] After a certain period of time, a very random increase in power began to start.

[Time Stamp: 02:49] One twenty-three … 40 seconds: at a order of the shift supervisor all the controls were dropped into the core.

[Time Stamp: 02:58] However, the reactor had been brought to such a situation by the staff that the scram system couldn’t prevent the accident. The designers had never designed for such a sequence of violations of regulations.

[Time Stamp: 03:13] According to witnesses outside Unit 4, at one twenty-three 40 seconds there were two explosions in sequence.

[Time Stamp: 03:23] Hot sparks and pieces flew out of the building.

[Time Stamp: 03:27] The chain reaction ceased after the explosion, but very high temperature fragments led to thirty centers of fire in the core.

[Time Stamp: 03:41] Then there was a tremendous fire, the fire brigade came and by 5 o’clock in the morning the fire was put out.