ENVIRONMENTAL DISASTERS Section 6.4 & 6.5

Section 6.4- Solutions to Thermal Pollution Once Through Cooling Method – (most common) uses water from a river or lake and returns it after it absorbs heat from a condenser; can be a problem in aquatic ecosystems Cooling Towers – prevents thermal pollution, but can be expensive to build Cooling Ponds – a nice alternative that can be used to house fish that like warm water, but land must be available

Waste-Heat Greenhouses Crop producers can utilize waste heat from a power plant to help reduce energy costs in growing their vegetables Warm water normally sent to a cooling tower is sent through pipes to heat-exchange systems in the greenhouses A back-up system must be used for additional heat and for when the power plant is shut down Energy costs are reduced by about 80%

Aquaculture with Wastewater Brunner Island, Penn. – Power Plant produces electricity and catfish with an experimental fish farm – aquaculture A coal-fired power plant discharges its heated wastewater to heat a greenhouse producing hydroponic grown vegetables August through March The wastewater is also used to heat incubators for hatching catfish eggs; once hatched they are transferred to long concrete pools Warm wastewater also helps keep the pools around 80oF (the optimum temperature for catfish is 84oF) It takes 36 weeks for the catfish to become the size they would in about two to three years in a natural environment

Section 6.5- Three Mile Island March 28, 1979 along Susquehanna River in Pennsylvania, the Three Mile Island Nuclear power plant A pressure relief valve opened and remained open allowing coolant water to escape, causing the temperature of the core of the reactor to exceed 5,000 oF The reactor’s containment vessel was designed to prevent the release of radioactive materials, and it did function properly Only low levels of radioactive gases were released Five years after the accident the state conducted a study to compare new cancer cases to those that would have normally been expected, called an observed vs. expected survey

Total cancer cases, breast cancer in females, respiratory, digestive system and skin cancers were compared The study showed no pattern in cancer incidence in relation to the distance from the Three Mile Island power plant There was also no “rising trend” in leukemia found Numerous studies have occurred as a result of the accident; however, not all findings are in agreement Some point to increased cancers as a result of the accident and others do not Regardless of the real effects of the accident, it is one that we can learn from