Hypothetical Nuclear Power Plant Incident

At 7:41 p.m. on a Saturday evening in August (when electricity demand in the region is near its peak), a nuclear power plant in the Midwest was struck by a powerful tornado. It is now 9:00 p.m. that same evening. Approximately 15 minutes ago (at 8:45 p.m.), a plant spokesperson made a public announcement to the local media including the following additional information:

• The tornado struck the plant’s secondary containment structure, tearing a 5 foot x 5 foot hole in the structure’s roof. The full extent of the damage to the secondary containment structure is not known at this time.
• There are no indications that the nuclear reactor vessels or the primary containment structure suffered any damage.
• The tornado destroyed the substation immediately adjacent to the secondary containment structure. As a result, the plant is now “off the grid,” meaning that the plant is neither receiving electricity from the grid nor delivering electricity to the grid.
• Flooding damaged the plant’s backup generators and contaminated the diesel fuel that would power the generators.
• As a result of the direct damage from the tornado and the flooding, the plant’s primary and secondary sources for running the plant’s water pumps (which are necessary to provide water to “cool” the nuclear reactors and to maintain the water levels in the spent fuel rod storage pool) have failed.
• As soon as the substation was destroyed, the plant’s computer system automatically initiated an emergency shutdown of the two nuclear reactors. All indications are that the reactors were shut down safely. With the plant’s pumps not working, the reactor cores will remain stable for at least 8 hours; however, it is unknown precisely how long the reactors will remain stable beyond 8 hours without the plant’s pumps providing water to cool the reactor cores.
• It is unclear when power can be restored to the plant’s pumping/cooling systems.

Additional Details (these were not included in the spokesperson’s statement but are general facts regarding the plant and the surrounding area):

• The plant consists of several structures:
1. The nuclear reactor vessels (two General Electric boiling water reactors) that contain nuclear fuel rods as well as “control” rods (control rods are automatically inserted into the reactor to stop the nuclear chain reaction whenever the reactor needs to be shut down).
2. The primary containment structure (a reinforced concrete dome built to withstand significant forces and that is designed to contain nuclear radiation in the event of a meltdown of the reactor’s core).
3. The secondary containment structure (a warehouse-type concrete and steel structure built over and surrounding the primary containment structure). In addition to providing additional containment in the event radiation leaks from the reactor’s core, the secondary containment structure also houses a swimming pool-sized pond in which 5 years’ worth of “spent” nuclear fuel rods are submersed in water for storage purposes. The water level in the storage pond is kept constant by the plant’s pump system, which operates to keep water levels in the pool high enough so that the rods always remain submerged and therefore cannot release radiation into the atmosphere.
4. An electrical substation, where power generated at the plant is connected to high-voltage transmission lines that transport the electricity generated at the plant to the region’s electrical system. The connections at the substation also provide power from the electrical grid to the plant to power the plant’s systems.
5. Backup diesel generators and diesel storage tanks. The generators are to be used to provide temporary power to the plant in the event the plant is disconnected from the regional electrical grid.
• Construction on the site began in the mid-1960s and the plant went into operation in 1973. It is operating under an existing license that expires in 2032. There have been only minor safety violations reported at this plant in its history.
• Each reactor has a capacity of 870 net megawatts (MWe). The combined annual output of the plant is 14.8 million megawatt hours (MWh).
• Electricity from the plant serves approximately 1.2 million homes in the region.
• There are approximately 400,000 individuals living within 20 miles of the plant site and there is a major metropolitan area of over 8 million people located 180 miles to the east of the plant. The prevailing winds under normal weather conditions travel from west to east/southeast.
• The plant is owned by 2 investor-owned utilities. The 75% owner is a major utility in the Midwest and the East that owns and operates several nuclear power plants. The majority owner has the ability to replace power in the event the nuclear plant is offline; however, their ability to do so in this case is significantly hampered by the damage done to transmission lines by the tornado. The minority (25%) owner is a much smaller regional investor owned utility that has limited capacity to replace the power lost if this nuclear plant loses the ability to generate power.
• The plant is located on a 765 acre site in the Midwestern United States, on the Mississippi River. The plant uses water from the river as the primary source for cooling the reactor and for maintaining the water level in the spent fuel storage pool.
• The 500-mile area surrounding the plant is predominantly agricultural and produces significant quantities of corn, other grains and soybeans. In addition, the plant is located in the center of a region known for its pork production.
• There is a major recreational area along the river, just to the east and north of the plant site.