Fault Tree Analysis of an Industrial Accident

Fault Tree Analysis of an Industrial Accident
Accident Description
-425453721735Figure SEQ Figure \* ARABIC 1: Diagram of Three Mile Island Nuclear Power Plant 2Source: Nuclear Safety Analysis Center (1980)00Figure SEQ Figure \* ARABIC 1: Diagram of Three Mile Island Nuclear Power Plant 2Source: Nuclear Safety Analysis Center (1980)The Three Mile Island, Pennsylvania accident was a 1979 nuclear powerplant meltdown caused by a mechanical failure in the cooling system. The mechanical failure led to the core meltdown of the second reactor. Additionally, radioactive gas leaked through the walls. Fortunately, there were no injuries. The powerplant had two reactors, both using a pressured water system. The first reactor produced 880 megawatts, while the second produced 959 megawatts (Nuclear Safety Analysis Center, 1980). Interestingly, the second reactor was brand new at the time of the accident, while the first had been in use for five years. The mishap in unit 2 occurred at 4 am when the reactor was working at 97% power (Nuclear Safety Analysis Center, 1980). It comprised of a glitch in the secondary cooling circuit, which raised the temperature in the primary coolant. Resultantly, the reactor shut down within one second. However, a pilot-operated valve failed to close, leading to a large amount of essential coolant escaping further, causing the meltdown of the reactor.
The valve on the reactor cooling framework opened shortly after the shutdown. However, it did not shut down after 10 seconds. Staying open, it released crucial reactor coolant to the coolant channel tank (Nuclear Safety Analysis Center, 1980). The administrators believed the valve had closed since the computer signalling system showed it had. Nonetheless, they lacked an instrument showing the valve’s exact position. High-pressure infusion pumps pushed water into the reactor framework in response to the cooling water deficiency. Eventually, cooling water flooded the pressurizer, which kept it from boiling. Operators answered by lessening the progression of increasing water and finally shut down the pumps because of the feared pipe damage that would cause a rupture. Consequently, the reactor coolant evaporated, uncovering the core, which became hotter, damaging the fuel rods and releasing the radioactive substance into the water.
Fault Tree Analysis (FTA)
Components of the System
The macronuclear powerplant system is a pressurized water reactor system with the following components as represented in figure 1 above:
* The reactor building houses a pressurized relief tank, pressurized relief valve, block valve, safety valve, control rods, steam generator, reactor coolant pump, and the reactor core.
* The turbine building consists of the turbine, generator, condenser, condensate pump, and main water feeding pump.
* Cooling tower for cooling the flowing coolant water.
* Transformer.
In this accident, the top event was the nuclear core meltdown leading to radioactive material leakage and a lack of power production. Basic events in the turbine building include power circuits, main feed water pump, circulating water pump, condensate pump, and condenser. Additionally, basic events in the reactor building include a pressurized relief tank,...