Human Factor III: The Impact of a Boiling Water Nuclear Reactor
Although my parents, my four brothers and I live in Pennsylvania, my mother is from New Jersey. Growing up, we continued my mother's custom of spending summers exploring the New Jersey shore. For four years I attended marine biology camp along New Jersey's Barnegat Bay and caught my mother's abiding passion for the Barnegat Bay Estuary and its surrounding habitats, including the magnificent and unique Pine Barrens, a forest like no other in the world.
This was the third year I had worked in the Barnegat Bay Estuary. During the first year, I studied whether the bay's water quality has declined over the past five decades, as the population around it has more than quadrupled. I collected and analyzed water samples for 11 indicators of water quality. I compared my data to 40 years of historical water-quality data from public databases. I concluded that there has been a decline in the bay's water quality.
The second year I studied the relationship between water quality and the presence of gram-negative pathogen-indicator bacteria. I cultured and counted bacteria, and prepared and studied microscopic slides of bacteria. I concluded that temperature, pH, nitrate-nitrogen, and dissolved oxygen affect bacteria growth in the bay, but salinity does not.
For each of these projects, I have benefited from people who were willing to talk to me about my projects and about Barnegat Bay. I also saw firsthand how careless and thoughtless some people are about the bay, treating it like a giant trashcan and being unmindful of how human activities impact the bay. I applied for and received two U.S. Environmental Protection Agency-sponsored grants to write and illustrate a pamphlet about what people can do to conserve and protect the bay. I distributed copies of the pamphlet to every realtor on Long Beach Island. To date, over 12,000 pamphlets have been given to people who rent homes along Barnegat Bay.
As I traveled around the bay collecting samples, I learned there is a nuclear reactor operating in the Barnegat Estuary. I learned more about the reactor and how it was constructed and became increasingly intrigued about the impact of the reactor on the estuary.
This essay summarizes my study of the surface water in the intake and discharge creeks of the oldest of the nation's 103 operating commercial nuclear power plants, Oyster Creek. Oyster Creek came on line in 1969, five years before the United States established the Nuclear Regulatory Commission (History of Nuclear Energy, 2003). Oyster Creek is a boiling water reactor, one of 34 remaining in the United States. It is near Forked River, a sleepy town in the Pine Barrens, on the Barnegat Bay Estuary in New Jersey. The reactor sits at the artificially created confluence of the South Branch of Forked River (the intake creek) and Oyster Creek (the discharge creek). The reactor draws over 4.5 billion liters of water daily from Forked River Creek, heats the water, and discharges it into Oyster Creek (O'Malley, 2004). The Atlantic Ocean is 16.09 kilometers (10 miles) away.
I studied the reactor's impact on its intake and discharge creeks. I compared the two creeks' microbial communities, bacteria counts, and 11 water-quality parameters to those in a nearby, but not directly impacted, control creek. My field research was conducted from July through November 2005. I collected samples at three sites in each of three creeks in the Barnegat Bay Estuary. I am not aware of any prior study comparing these intake and discharge creeks.
My hypotheses were that the reactor affects the water quality in both the intake and discharge creeks; that the microbial communities in the intake and discharge creeks would be different than the one in the control creek; and that there would be fewer bacteria in the discharge creek.
The Oyster Creek Reactor
The Oyster Creek Reactor has transformed Oyster Creek and the South Branch of Forked River into part of the bay (Generic Environmental Impact, 1995). Forked River, the intake creek, and Oyster Creek, the discharge creek, are approximately 11.26 kilometers (7 miles) north of Cedar Creek, the control creek, along the 67.59-kilometer-long (42 mile) bay.
The original heads of Oyster Creek and Forked River were in New Jersey's Pine Barrens, a unique, 445,194 hectare (1.1 million acre) ecosystem of extensive pine forests fringed by salt water marshes (Jorgensen, 2001). These creeks were crystal-clear streams, brackish and tidal, each flowing east from the Pine Barrens into the bay. In what, at least in hindsight, seems a surprising decision, permission was given to dramatically alter those beautiful creeks to construct the Oyster Creek nuclear reactor. Beginning in 1964, the creeks were widened and deeply dredged, the direction of Forked River was completely reversed, and the creeks were joined at the reactor.
The crystal-clear water is gone, and the shallow, gently flowing creeks have disappeared. Both creeks now flow forcefully in opposite directions, controlled by the reactor, not the tides. The South Branch of Forked River flows west, daily moving over 4.5 billion liters (approximately 1.2 billion gallons) of salt water from the bay upstream into the power plant (O'Malley, 2004). Oyster Creek is now a one-way discharge creek flowing east (Generic Environmental Impact, 2005).
Analysis of microbial communities with EcoPlates™ assays
I used EcoPlate™ assays to study the microbial communities in each creek. Each EcoPlate™ (Biolog, CA) contains 96 wells: three replicates of 31 wells with seven different carbon substrates and three wells containing water. The carbon substrates are grouped into six categories: polymers, carbohydrates, carboxylic acids, amino acids, amines, and phenolic compounds. I inoculated the EcoPlates™ with water, using a pipette. As the microbe community in the inoculum respires, a tetrazolium dye is reduced, the water color changes, and a purple formazan accumulates in the wells. The color change produces a "metabolic footprint" of the microbial community (Microbial Community Analysis, 2004). Because the microbial community is at the bottom of the food chain, changes in the community often predict overall environmental alteration (Microbial Analysis, 2004). I used a microplate reader to assess the optical densities, applied principal component analysis to the data, and created cluster graphs for each substrate.
Analysis of bacteria colonies with agar cultures
There are many types of agar. Selective media inhibit some bacteria from growing. Differential media allow most bacteria to grow, causing some bacteria to change color, which aids identification. Some media are both selective and differential. The agars I used in this study were Nutrient and MacConkey's. Nutrient is non-selective and grows both gram-negative and -positive bacteria. MacConkey's is selective and differential, grows only gram-negative bacteria, and colors some bacteria (Fankhauser, 2001).
The 11 Water Quality Indicators
1. Ammonia-nitrogen. Ammonia-nitrogen, reported as ppm, is a dissolved and highly reduced form of nitrogen in water. High levels of ammonia can kill fish and indicate pollution. Major sources of ammonia include fertilizers, industrial waste by-products, and excretion from fish gills and urine. Ammonia and nitrite harm fish, while nitrates do not (Mengel, 1998). High levels of ammonia can decrease fish egg hatch rates and damage fish gills, livers and kidneys (Phona, 2002). Low dissolved oxygen levels can mean high ammonia levels, because the bacteria that nitrify ammonia need oxygen.
2. Biochemical oxygen demand. Biochemical oxygen demand (BOD) is the amount of oxygen used by the organic matter in water. With rapid use, BOD rises and less oxygen is available. If BOD is too high, organisms suffocate. There are many sources of BOD, including plants, animals and animal waste, and microorganisms (Background on Chemical Parameters, 2004).
3. Carbon dioxide. Carbon dioxide results from the respiration of organisms that use oxygen and release carbon dioxide. Plants absorb carbon dioxide and release oxygen. High carbon dioxide levels make it difficult for fish to use dissolved oxygen, because fish must discharge carbon dioxide before taking in oxygen. As carbon dioxide increases, pH levels decrease (Explanation of Water Quality, 2004).
4. Conductivity. Conductivity, which is measured in micromhos (mho) per centimeter, is a "numerical expression of water's ability to conduct an electrical current" (Plona, 2002). Pure water is a poor conductor. Dissolved organic solids hinder conductivity, while inorganic solids like sodium and iron encourage it (Background on Chemical Parameters, 2004). Conductivity is a reliable indicator of water quality because it is relatively constant in a body of water (Explanation of Water Quality, 2004).
5. Dissolved oxygen. Dissolved oxygen (DO) refers to the amount of oxygen in water. Weather, salinity, and temperature can affect dissolved oxygen. Cool water holds more dissolved oxygen (Background on Parameters, 2004). A thermal discharge, like that from the Oyster Creek reactor, can reduce DO. Fish are cold-blooded animals, using more oxygen at higher temperatures, when their metabolism increases and they need more DO (Explanation of Water Quality, 2004).
6. pH. pH measures the acidity or alkalinity of a liquid on a scale from 0 to 14, with 7 being neutral, lower numbers more acidic, and higher numbers more basic. Each number is 10 times more acidic than the number above it (Explanation of Water Quality, 2004). For most organisms, a pH between 6.5 and 8.5 is acceptable, while pH levels of 7.0 to 8.0 are ideal (Background on Chemical Parameters, 2004).
7. Nitrate nitrogen. Nitrate-nitrogen, reported as ppm, is the most common form of nitrogen in water. It forms when bacteria nitrify (or transform) nitrite-nitrogen, and it harms aquatic life only at high levels (Mengel, 1998). Another source of nitrate-nitrogen is fertilizer runoff. It is a key nutrient for algae, and high levels can cause algae to grow too fast and harm fish populations, because algae use the dissolved oxygen that fish need.
8. Salinity. Salinity measures the percent of salt particles in the water in three groups: seawater (greater than 3 percent); brackish water, the water studied here (0.05 percent to 3 percent); and freshwater (less than 0.05 percent) (Background on Chemical Parameters, 2004).
9. Temperature. Water temperature is critical to water quality. It affects dissolved oxygen levels, plant photosynthesis, and the sensitivity of organisms to disease, toxic waste and parasites. Temperature determines which organisms can survive in an ecosystem; plants grow faster and oxygen levels decrease at higher temperatures (Background on Chemical Parameters, 2004).
10. Turbidity. Turbidity, reported as nephelometric turbidity units (NTU), measures the amount of sediment in water (water clarity) by how much the organic and inorganic particles in the water scatter light. The particle total is the "suspended load." The larger this load, the more light it scatters, and the higher the turbidity (Turbidity, 2001). High turbidity results in less sunlight, less plant growth, fewer food sources for the food chain, and higher temperatures because the suspended particles absorb heat (Background on Chemical Parameters, 2004).
11. Velocity. Water velocity measures how far water travels in a given time in meters per second (m/s) (Water Velocity Censors, 2005). Certain organisms prefer a particular velocity (Thomas, 1998). Organisms use less energy to breathe and find food in slower water, because in rapid water they must move continuously (Aquatext, 2004).
Materials and Methods
I obtained water-quality testing materials from two science supply houses, Wards Henrietta in NY and Carolina Biological in NC. I analyzed the creeks' microbial communities by inoculating EcoPlates™ with a pipette and reading the plates with a microplate reader for optical densities. I cultured the water samples on two types of agar in a BSL 1 laboratory using petri dishes. I used standard chemical testing procedures to test water-quality indicators except for conductivity, dissolved oxygen, pH, salinity, temperature and turbidity, salinity, temperature and turbidity. I used a Horiba U22XD multi-parameter testing device to test those indicators.
Forked River Compared to Cedar Creek
In Forked River, the intake creek, BOD, carbon dioxide, pH, velocity, and EcoPlate™ amines showed significant differences compared to Cedar Creek, the control creek. BOD in Forked River was an average 3.3 percent lower than in Cedar Creek, and carbon dioxide was an average 7.9 ppm lower. pH was 0.4 higher in Forked River and velocity was 0.4 m/s faster. Dissolved oxygen (DO) t -tests showed a borderline difference between Forked River and Cedar Creek, while there were no significant differences in ammonia-nitrogen, conductivity, salinity, temperature, turbidity, MacConkey's and nutrient agars, the overall EcoPlate™ readings, carboxylic acid, polymers, carbohydrates, amino acids, and phenolic compounds.
I compared water samples from different sites along Forked River and Cedar Creek. Carbon dioxide and velocity showed significant differences throughout Forked River and Cedar Creek. Nutrient agar, which showed no difference creek to creek, shows significant differences at the heads and middles of the creeks, and a borderline difference at the mouths. BOD, nitrate-nitrogen, and turbidity all showed a significant difference only at the heads of the creeks. MacConkey's agar showed a borderline difference only at the heads. DO and amines showed differences only at the mouths, and EcoPlate™ phenolic compounds showed a borderline difference only at the mouths.
Between Forked River and Cedar Creek, the heads of the creeks showed the most difference, with seven of the t -tests showing differences, 12 showing no differences, and one showing a borderline difference. The mouths of the creeks were next, with five showing differences, 14 showing no differences, and one showing a borderline difference. The middles of the creeks showed the least difference: three showed differences, and 17 do not.
Oyster Creek Compared to Cedar Creek
The pH in Oyster Creek was an average 0.4 higher than in Cedar Creek. The temperature was an average 6°C. higher. Turbidity was an average 6.3 NTU greater. Velocity was an average 0.5 m/s faster. The number of colonies cultured on the MacConkey's agar increased by an average of 48 bacteria between Oyster Creek and Cedar Creek, and the number of colonies on nutrient agar increased by 31 colonies. BOD and carbon dioxide showed only borderline differences. There were no significant differences in ammonia-nitrogen, conductivity, DO, nitrate-nitrogen, salinity, the overall EcoPlate™ readings, carboxylic 6 acid, carbohydrates, amino acid, phenolic compounds, and amines.
I compared the results for individual sites along Oyster Creek and Cedar Creek. Temperature, velocity, and the number of human-pathogen-indicator bacteria colonies on MacConkey's agar were significantly greater in Oyster Creek than in Cedar Creek. The number of bacteria colonies on nutrient agar was significantly different in the heads and mouths of Oyster Creek. There was a borderline difference in the middle of the creek, and the total number of bacteria was significantly different throughout the discharge creek. EcoPlate™ carboxylic acids, amino acids and phenolic compounds showed significant differences at the heads of the creeks, and DO and carbon dioxide showed significant differences only at the mouths of the creeks.
The t -test results for the heads of Oyster and Cedar Creeks showed the most difference, with nine showing significant differences and 11 showing none. The mouths of the creeks were next, with seven showing differences and 12 showing no differences. The middles of the creeks showed the fewest differences, with four showing differences, 13 no differences, and three borderline differences.
Oyster Creek Compared to Forked River
There were no significant differences in carbon dioxide, conductivity, salinity, temperature, turbidity, velocity, MacConkey's and nutrient agars, and EcoPlate™ amines. Carbon dioxide had an average difference of .9 ppm. Forked River had an average 1.2 greater conductivity and 0.09 greater salinity.
Oyster Creek had an average of 5°C. higher temperature, an average 4 NTU higher turbidity, and an average 0.15 m/s faster velocity. Human-pathogen-indicator bacteria colonies averaged 43 higher, and the total number of bacteria averaged 28 higher in Oyster Creek.
Carbohydrates showed a borderline difference. There was no significant difference in ammonia-nitrogen, BOD, DO, nitrate-nitrogen, pH, the overall EcoPlate™ readings, carboxylic acid, polymers, amino acid, and phenolic compounds.
I then compared my data for individual sites along Forked River and Oyster Creek. Salinity, temperature, MacConkey's, and the nutrient agar showed differences in all three sites. Velocity, pH, the overall EcoPlate™ readings, and carboxylic and amino acids showed significant differences only at the heads. Turbidity showed a borderline difference at the heads. Carbon dioxide and DO showed a significant difference at the mouths.
The heads of the creek showed the most difference, with 11 t -tests showing significant differences, eight showing no significant differences, and one showing a borderline difference. Next were the mouths of the creeks, with seven significant differences, 12 showing no differences, and one borderline difference. The middles of the creeks showed the fewest differences, with six significant differences, 12 showing no differences, and one borderline difference.
Several observations hold true for all three creeks. There was never a difference in the middle of a creek if there were no differences in at least one of the other sites. When there was only one difference in the three tests, the differences were usually at the head of the creek.
I concluded that the nuclear power plant affects the water quality and microbial communities in the plant's intake and discharge creeks. While there might have been some natural environmental variations between the two creeks if they had been left in their natural state, today that is no longer the case. There are differences in the three creeks that can reasonably be attributed to the nuclear reactor.
One striking example of the nuclear reactor's effect on Forked River and Oyster Creek is the change in those creeks' velocities compared to Cedar Creek. This is explained by the sheer amount of water being pulled through the creeks by the reactor. Also, the flow of Forked River is reversed, which is explained by the force of the reactor sucking water in from Barnegat Bay. The increase in velocity explains the higher turbidity in Forked River and Oyster Creek compared to Cedar Creek; the faster water is picking up and carrying more sediment. Also, Oyster Creek has a higher turbidity than Forked River, which is explained by the force with which the water discharged from the reactor is stirring up sediment.
The EcoPlate™ data showed differences in the microbial communities in Forked River compared to Cedar Creek. The explanation for this is that Forked River has been turned into an arm of the bay, while Cedar Creek remains in its natural state.
The pH in both Oyster Creek and Forked River is 0.4 higher than the pH in Cedar Creek. The explanation for this is that water is drawn by the plant through Forked River and then released into Oyster Creek. It is water from the Barnegat Bay, and the bay's pH almost exactly matches that of Forked River and Oyster Creek (Roda, 2004).
The plant's discharge of hot water into Oyster Creek explains the 6°C. higher temperature difference between Oyster Creek and Cedar Creek and the 5°C. higher temperature between Oyster Creek and Forked River. No apparent natural cause accounts for these dramatic temperature differences between Oyster Creek and the other two creeks. The temperature differences also likely affect other indicators in Oyster Creek.
The higher temperature in Oyster Creek would explain the higher average numbers of bacteria in Oyster Creek compared to Cedar Creek and Forked River. Higher temperatures would especially affect the number of human-pathogen-indicator bacteria, because pathogens survive best at the human body temperature of 37°C.
The higher temperature caused by the plant also explains the colony count data within Oyster Creek. On both agars, bacteria numbers at the head of Oyster Creek were extremely small, with the lowest average colony counts of any site studied. By contrast, the petri dishes plated with water from the other two Oyster Creek sites had by far the highest average of any site studied; they were consistently covered with one type of bacterium seen at no other site, and they showed few if any colonies of any other kind. An explanation is that most bacteria are killed in the reactor by the intense heat, which explains the low colony counts at the head of the creek. By the time the water gets to the middle of the creek, however, the cooling of the water has created an ideal environment for this one type of bacterium, whose population explodes and continues to increase throughout the rest of the creek.
As a researcher, it was amazing to stand in Cedar Creek in late fall and measure water temperatures in single degrees Celsius, while freezing in a thick wetsuit. Yet in Oyster Creek, the water remained—if not warm—at least comfortable in a wet suit; I could feel the change in temperature as I turned into the creek from the bay.
Perhaps the most important differences found in this project are those between Oyster Creek and Forked River. These two creeks would have been much more similar if they were unaffected by outside forces. They are close together, flow through almost identical environments, have sources close to each other, are almost the same length and width, and if human presence is considered, have the same kind and amount of development along their lengths. However, they have become very different. They are also more different from each other than either one is from the control creek. The only explanation is the operation of the Oyster Creek nuclear reactor. Key differences include the higher temperature, turbidity, and velocity of the water in Oyster Creek, and the difference in the number and type of bacteria in the creeks.
The reactor increases the variability of water-quality indicators and number of bacteria colonies in Oyster Creek and Forked River, compared to the variations within Cedar Creek. The reactor's operation explains why EcoPlate™ data show fewer differences between Forked River and Oyster Creek than in Cedar Creek. The reactor has reduced the microbial diversity in the creeks. The agar study results for Oyster Creek support this observation. There is one dominant and highly populous kind of bacteria in the middle and at the mouths of the creek, and almost no other kind of bacteria.
My overall hypothesis that the Oyster Creek reactor has affected the water in its intake and discharge creeks was accepted. My hypothesis that the reactor affects the water quality in the creeks was accepted. My hypothesis that the microbial communities in the intake and discharge creeks would be different from a control creek was accepted. My hypothesis that there would be fewer bacteria in the discharge creek was rejected; there were almost no bacteria at the head of that creek, but far more in the middle and at its mouth than at any other site studied.
The study strongly suggests that the reactor's release of heated water into the discharge creek has altered the water parameters and the microbial community in that creek. This alteration could be prevented if the water were cooled to its natural temperature before being discharged. Technology is available to perform residual heat removal (RHR) and is being used in more modern reactors.
Oyster Creek has applied for a 20-year license extension. There are 34 boiling water reactors similar to Oyster Creek operating in the United States and 60 more worldwide, mostly in Japan and Sweden (Information and Issues, 2005). Many of the reactors operating in the United States will apply for license operating extensions within the next decade. As a condition of license renewal, the companies that own and operate these reactors could be required to install systems to cool the water before discharge, which would substantially avoid altering the ecosystems in the discharge creeks of these reactors.
- The Oyster Creek reactor has affected the water in its intake and discharge creeks. The reactor affects biochemical oxygen demand, carbon dioxide, conductivity, temperature, turbidity, velocity, pH and salinity.
- The reactor has no effect on dissolved oxygen, ammonia-nitrogen, or nitrate-nitrogen.
- The microbial communities are different in the intake and discharge creeks.
- There are almost no bacteria at the head of Oyster Creek but far more in the middle and at its mouth than at any other site studied.
- There is one bacterium in the middle and at the mouth of Oyster Creek that appears in small translucent colonies and grows prolifically on MacConkey's agar. I had not observed this morphotype before in any other site, in any of the multiple bacteria studies I have conducted in the estuary.
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Dr. James Fenwick, professor of applied statistics at Millersville University, and Dr. Brian Adams, assistant professor of computer science at Franklin & Marshall College, taught the researcher statistical methods for data analyses. Dr. Pamela Vercellone Smith, research associate at Pennsylvania State University, assisted in the microbial community study design by recommending EcoPlates™. Dr. Andrew Draxler of the National Oceanic and Atmospheric Administration, based at the James J. Howard Marine Sciences Laboratory in Sandy Hook, NJ, provided background about Oyster Creek and the surrounding area. Mrs. Vasantha Kittappa, chair of the Science Department at Lancaster Catholic High School in Lancaster, PA, was the teacher/sponsor of the study.
More About This Resource...
This winning entry in the Museum's Young Naturalist Awards 2006 is from a Pennsylvania 10th grader. Anastasia studied the water quality and microbial communities in both the intake and discharge creeks near the reactor. Her essay includes:
- an overview of the Oyster Creek Nuclear Generating Station and of her previous research projects;
- details about the methods and materials she used to study the water quality and microbial communities; and
- the results of her investigation and her conclusions, which include that the reactor affects biochemical oxygen demand, carbon dioxide, conductivity, temperature, turbidity, velocity, pH, and salinity.
OriginYoung Naturalist Awards