Water System example essay topic

The Three Mile Island Disaster - An Organizational Communication Study The accident at the Three Mile Island Unit 2 nuclear power plant near Middleton, Pennsylvania, on March 28, 1979, was the most serious in U.S. commercial nuclear power plant operating history. Even though it led to no deaths or injuries to plant workers or members of the near by community, it did bring about sweeping changes involving emergency response planning, reactor operator training, human factors engineering, radiation protection, and many other areas of nuclear power plan operations. It also caused the U.S. Nuclear Regulatory Commission to tighten and heighten its regulatory oversight. Resultant changes in the nuclear power industry and as the NRC has the effect of enhancing safety.

The accident began at about 4: 00 am on March 28, 1979, when the plant experienced failure in the secondary, non - nuclear section of the plant. The main feed water pumps stopped running, caused by either a mechanical or electrical failure, which prevented the steam generators from removing heat. First the turbine, then the reactor automatically shut down. Immediately, the pressure in the primary system (the nuclear portion of the plant) began to increase.

In order to prevent the pressure from becoming excessive, the pressurizer relief valve (a valve located at the top of pressurizer) opened. The valve should have closed when the pressure decreased by a certain amount but did not. Signals available to the operator failed to show that the valve was still open. As a result, the stuck open valve caused the pressure to continue to decrease in the system.

(Stencel p 2) Another problem began to occur as the emergency feed water system was tested 42 hours before the accident. As a part of the test, a valve is closed and then reopened at the end of the test. But this time through either an administrative or human error, the valve was not reopened, which prevented the emergency feed water system from functioning. This was discovered eight minutes into the accident and was corrected, allowing cooling water to flow into the steam generators. As the system pressure began to decrease voids in water began to occur causing portions of water to redistribute and the pressurizers began to become filled with water. This caused false readings in the level indicator, causing the operator to stop adding water, which cause inadequate cooling and the nuclear fuel overheated.

This caused hydrogen to be released into the reactor containment building. Worries of a "meltdown" began, and small leaks I the reactor coolant system which caused high radiation in parts of the plant and also a small amount released into the environment. (Stencel p 2).