Characterization of Phytoplankton Community Changes in Barnegat Bay Related to the Closure of Oyster Creek Nuclear Generating Station, Combining Next Generation Sequencing and Microscopic Analyses
Project Background Oyster Creek Nuclear Generating Station (OCNGS) is the oldest operating commercial nuclear power plant in the United States and began operating in December 1969. The facility is located between the South Branch of Forked River and Oyster Creek in Ocean County, about 3.2 km inland from Barnegat Bay, New Jersey . The facility consists of a single unit of boiling water reactor with once-through cooling water system. The system intakes water from Forked River through two surface water intake structures: the Circulating Water Intake which withdraws water up to an amount of 662 million gallons per day (MGD) to cool the reactor, and the Dilution Water Intake which withdraws up to 732 MGD of water to moderate the thermal effects from the cooling water. All intake water is discharged into Oyster Creek via a discharge canal and further downstream to Barnegat Bay. The plant is licensed to operate until April 2029 but is scheduled to be permanently shut down by October 2018. Upon the closure, there will an approximately 95% reduction in water intake, from approximately1,400 MGD to 57.6 MGD.
The construction and operations of OCNGS have large impacts to the hydrology, chemistry and biology of Barnegat Bay and its two tributaries Forked River and Oyster Creek (Summers et al. 1989). Prior to the construction, Forked River and Oyster Creek were small, spring-fed, cedar-swamped brooks of typical freshwater and tidal freshwater (0.5 ppt) systems. The construction of the facility have completely altered the flow of the water in Forked River and Oyster Creek and made them a physical extension of Barnegat Bay with salinity generally ranges around ~25 ppt, similar to that in the center of the Bay (Summers et al. 1989). During its normal operations, impingement, entrainment and thermal effects are the major concerns to fishery resources and natural populations in the area. Large organisms, mainly fish and crabs, can be trapped on the intake screens and trash racks and become impinged. Small organisms which are entrained to the cooling system will be exposed to sudden temperature rise of 12-13 °C and up and a lethal level of chlorine (Summers et al. 1989). Survived organisms continue to be exposed the excessive temperature while transiting down the discharge canal. In addition, organisms in receiving waters can be exposed to elevated temperatures in the discharge plume. In many cases of facility shutdown (Summers et al. 1989, GPU report, 2000), the sudden temperature drop (e.g. ~10°C within 15 minutes in January 2000) had resulted to significant fish mortalities from cold-shock. During operation the facility also releases about 3.53 MGD wastewater and approximately 3.5 MGD chlorinated washwater from the radioactive waste treatment. Chlorine is considered toxic to most of the estuarine biota at the range of ppb to ppm and its toxicity is at greatest at high temperature. In addition, the discharge water may include residues of copper corroded from the condenser tubes, small amount of sodium, phosphorus, sulfates, chlorides, iron, oil and grease, and low levels of radioactivity, though, prior to discharge, wastewater discharges were analyzed to make sure the amount of radioactivity is within the acceptable limits (Summers et al. 1989).
The anticipated physical changes related to the closure of the OCNGS include the immediate and sharp temperature drops in Oyster Creek and milder temperature decrease in Barnegat Bay as secondary receiving water body. The study showed the 1.5°F above ambient summer thermal plume extending completely across Barnegat Bay () and such thermal effects will be almost removed after the closure. Meanwhile the largely reduced discharge can lead to the alteration of the water circulation patterns in mid-Barnegat Bay. It is important for us to understand and evaluation how the closure of OCNGS will affect the development of fishery resources and other community populations in the adjacent Barnegat Bay as well as the ecology and water quality of the estuarine ecosystem.