Civil Engineering Reference
In-Depth Information
1 Reactor core
9 Fueling machine
2 Core inlet pipe
10 Platform for fueling
3 Bottom radiation shield
11 Vertical channels for fuel
4 Collector - distributor
elements
5 Lateral radiation shield
12 Downcomer pipes
6 Steam separator
13 High-pressure collector
7 Steam-water pipes
14 Low-pressure collector
8 Top radiation shield
15 Main coolant pipes
Fig. 9.3
Schematic design of the Chernobyl reactor [
4
,
5
]
After the more or less stable power level at 200 MW(th) had been reached,
preparations of the experiment continued by activating extra water pumps. This led
again to coolant temperature variations and the operators responded by turning off
two of the circulating pumps. All these actions led to an extremely unstable reactor
state before the experiment began.
Almost all control rods had been removed manually to their upper limit. The
automatic control system together with other automated safety features had been
disabled.
The reactor coolant temperature was close to its boiling temperature.
The reactor was already outside of the safe operating envelope established
by the designers.
The experiment began by shutting off the steam to the turbine. The turbine
generators began to run down. The diesel generators started and picked up loads.
