Columbia Generating Station

updated Apr 14, 2011 by Nick Thorp

Overview

The Columbia Generating Station at the Hanford Nuclear Reservation, is the Northwest's only nuclear-power plant. The 1,150-megawatt reactor provides 9 percent of Washington's electricity.

The Columbia Generating Station's reactor is a boiling-water design from General Electric. It was completed in 1984 at a cost of $3 billion. There had been plans to build five reactors throughout the Northwest but due to financial problems the other plants were never constructed. In the early 2000s, there were proposals to complete one of the unfinished plants at Hanford, but it did not materialize. The Nuclear Regulatory Commission issued a 40-year operating license for the Columbia Generating Station in 1983. In 2010, the license was extended for an additional 20 years. All of Columbia Generating Station's power is sold at cost to the Bonneville Power Administration.

Operation

Columbia Generating Station primarily uses uranium as a fuel source to create nuclear fission. The heat generated by the fission turns water into high pressure steam. This steam is piped into large turbine blades causing the turbine shaft to spin at a speed of 1,800 rpm. This causes an electric generator rotor to spin, generating electricity. The steam goes through a condenser where it is cooled and turned into water. The water is then pumped back to the reactor to be reheated and turned back into steam, continuing the cycle. The heat from the condenser, carried by non-radioactive water, is released into the air through six cooling towers located outside the plant.

Columbia Generating Station has 185 control rods. These rods are mostly made of boron and can be moved in and out of the core. When they are inserted they absorb neutrons and slow the nuclear reaction. The strength of the reaction is controlled by how many rods are inserted and how far they extend into the core.

History

In the early 1990s, because of malfunctions and accidents, the Columbia plant was operational only 40 percent of the time. The cost for producing power was so high it was debated whether it made sense to continue operations. Although there have been several unplanned shutdowns, the plant has never had a radiation release. After a change in management and major repairs, the performance of the plant improved. The cost of generating power dropped from 5.8 cents a kilowatt hour in 1994 to about 2.5 cents today.

In 2002, the federal Nuclear Regulatory Commission cited the Columbia plant for inadequate emergency preparedness. In 2010 a review by the industry-funded Institute of Nuclear Power Operations singled the plant out as one of two in the country most in need of improvements in operations and "human performance."

Concern in light of Japanese nuclear crisis

The reactors at the Columbia plant are a similar design to the plants at the Fukushima Nuclear Power Plant, in Japan. When the Fukushima plants suffered explosions and partial meltdowns due to a 9.0 earthquake and a subsequent tsunami, the safety of the Columbia plant was publicly questioned.

The reactor at the Columbia plant was built to handle a magnitude 6.9 earthquake. Since being built, scientists have confirmed that geologic faults run from Richland across the Cascades as far west as Vancouver Island. These faults are capable of generating an earthquake as powerful as magnitude 7.5.

The Columbia reactor was designed to rely on cooling water pumped from the nearby Columbia River. If power for those pumps sputters out, the reactor has three diesel generators to fall back on. If those fail, as happened in Japan, batteries can power the pumps for eight hours.

After the Sept. 11th attacks, all U.S. nuclear plants were required to upgrade their backup systems. The Columbia plant added a portable diesel generator, and a system that can use steam from the reactor to power pumps. Also added was a fire truck that could pump water onto the core in extreme emergencies and a 30-day supply, with cooling water being stored on site.

Spent fuel rod storage

The Columbia Generating Station has an on-site dry cask storage installation, which allows for storage of spent fuel rods in specially designed and manufactured casks. To date, 27 casks have been loaded and stored in the new installation, making room in the spent fuel pool for receipt of new fuel.

If these pools are not kept cool, the fuel could melt, catch on fire, and release large amounts of radioactivity into the atmosphere. In 1997, a report requested by the Nuclear Regulatory Commission found that a severe pool fire could render about 188 square miles uninhabitable, cause as many as 28,000 cancer fatalities and cost $59 billion in damage.

Congress asked the National Academy of Sciences to review the vulnerabilities of spent nuclear fuel storage. They reported that "...nearly all pools contain high-density spent fuel racks. These racks allow approximately five times as many assemblies to be stored in the pool as would have been possible with the original racks, which had open lateral channels between the fuel assemblies to enhance water circulation."

The National Academy panel noted, "at U.S. commercial nuclear power plants, these pools are less well protected structurally than reactor cores... Almost all spent fuel pools are located outside of the containment structure that holds the reactor pressure vessel."

As of April 2011, the Columbia Generating Station's spent reactor pool has 558 metric tons of spent reactor fuel assemblies in it. This is 66% of what it is licensed to hold. The amount is twice what the Fukushima Unit 4 pool held when it caught fire. It is five times the amount in the Fukushima-Daiichi Unit 3 reactor.

Mox fuel

In March of 2011, it was discovered that officials a the Columbia Generating Station had been quietly discussing the use of mox fuel for at least two years.

While all uranium contains some amount of plutonium, mox fuel, which is a mixture of uranium and plutonium, contains a higher proportion of plutonium, between 5 and 9 percent. If there is an accident at a nuclear plant, the dangers are different if mox fuel is involved. During an accident, plutonium's heaviness will prevent it from being widely spread. But because its toxicity is so high, even small amounts can be dangerous. Also, with plutonium's longer half life, if it escaped from a burning reactor and contaminated soil downwind, it would remain hazardous for tens of thousands of years.

Energy Northwest felt that since Hanford's nuclear experts had experience in handling weapons-grade material, it would make senses for them to explore this technology. The information came to light when the watchdog group Heart of America Northwest sued the Energy Northwest, plant's operator. In a public records request, an email from an official at of Energy Northwest said ""I assume this info will stay between PNNL and DOE NNSA, just don't want any unexpected press releases about burning MOX fuel in (Columbia Generating Station)."
There was also a timeline indicating that mox fuel would be incorporated in 2013 and tested for six years. A phase up would following and have full operations by 2025. Energy Northwest officials said that the timeline was only theoretical, and also outdated.

No U.S. nuclear plants currently use the plutonium fuel. The advantageous to using mox fuel is that it could help draw down the stockpiles from weapons production and dismantling of nuclear warheads. The mox fuel could also be made more cheaply than regular uranium fuel.