South Texas Project Nuclear Operating Company (STPNOC) said it implemented its severe weather plan and completed hurricane preparations ahead of Hurricane Harvey striking the Texas Gulf Coast on 25 August.
The company said storm crews comprising some 175 workers – including operators, engineers, maintenance, emergency responders and security personnel – remained on-site for the duration of the storm.
STP president and CEO Dennis Koehl said, “At STP, the safety of our employees and neighbours in the local communities is our primary responsibility. Our team has done an outstanding job in preparing for this storm. Our continued commitment and focus is to put safety first in every action we take.
STP said it operates “under well-defined Nuclear Regulatory Commission guidelines and internal procedures”. Prior to storm, it said it would take steps to safely shut down the units if the projected sustained winds on-site exceeded hurricane force, 73 miles per hour (mph). However, on 26 August the company said the plant experienced overnight wind speeds lower than expected at between 30mph and 35mph (48km/h and 56 km/h). No storm-related issues that could impact operations were found. At that point, it said the focus shifted to “monitoring for flood or wind-driven rain events”.
“We continue to closely monitor and track the storm for potential reformation in the gulf over the next several days,” STPNOC said. “Potential challenges are road closures – impacted by flooding – that could present issues for employees travelling to and from the plant.”
The company noted the plant has steel-reinforced concrete containment with four-foot (1.2 meter) thick walls. The buildings housing the two reactors, vital equipment and used fuel have steel-reinforced concrete walls, four to seven feet (1.2 to 2.1 meters) thick, which are built to withstand hurricanes and tornadoes. The plant is located 10 miles (16 kilometres) inland and at an elevation of 29 feet (8.8m) above mean sea-level. The facility is designed with watertight buildings and doors, with all buildings housing safety-related equipment being flood-proof to an elevation of at least 41 feet (12.5m).
South Texas Project’s two 1280 MWe pressurized water reactors have been in commercial operation since the late 1980s. The units are owned by NRG Energy, CPS Energy and Austin Energy.
Harvey was upgraded to a category 4 hurricane on 25 August. At 6.00pm that day, it had maximum sustained winds at 130 mph. According to the US National Oceanic and Atmospheric Administration, Harvey brought over 25 inches (64cm) of rain to portions of southeast Texas since Thursday night. Although Harvey has now been downgraded to a tropical storm, another 10-20 inches is expected over parts of the upper Texas coast into southwestern Louisiana. Storm totals in some locations may approach 50 inches, it said. This is producing devastating flooding, with numerous flash flood warnings in effect.
Source: World Nuclear News