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Three Mile Island (1979)

Judge's Ruling (1996)

On March 28, 1979 Reactor 2 at the Three Mile Island nuclear power plant suffered a partial meltdown. Within weeks attorneys filed a class action suit against Metropolitan Edison Company (a subsidiary of General Public Utilities) on behalf of all businesses and residents within 25 miles of the plant.

Over 2,000 personal injury claims were filed, with plaintiffs claiming a variety of health injuries caused by gamma radiation exposure. The Pennsylvania district court quickly consolidated the claims into ten test cases.

Over the next 15 years, the case went to the Supreme Court and back, and through various district and appeals courts. Finally, in June 1996 district court judge Sylvia Rambo dismissed the lawsuit granting summary judgment in favor of the defendants (GPU).

Conclusion

The parties to the instant action have had nearly two decades to muster evidence in support of their respective cases. As is clear from the preceding discussion, the discrepancies between Defendants, proffer of evidence and that put forth by Plaintiffs in both volume and complexity are vast. The paucity of proof alleged in support of Plaintiffs, case is manifest. The court has searched the record for any and all evidence which construed in a light most favorable to Plaintiffs creates a genuine issue of material fact warranting submission of their claims to a jury. This effort has been in vain. The grave consequence of the court's decision to grant summary judgment in favor of Defendants is obvious -- thousands of individuals who believe that they have suffered adverse medical effects as a result of the TMI accident will not have an opportunity to have their claims heard by a jury of their peers.

SYLVIA H. RAMBO, Chief Judge
Middle District of Pennsylvania

Dated: June 7 1996.

 

To See a Simulation of the Accident, click HERE

Three Mile Island Unit 1 (TMI-1), located in Middletown, PA, is a nuclear generating facility capable of producing 875 megawatts. TMI-1 is a pressurized water reactor that, at full power, meets the electricity needs of a city the size of Philadelphia.

The plant began commercial operation in 1974. In December 1999, General Public Utilities sold TMI-1 to AmerGen, a joint venture of PECO (now Exelon) and British Energy, of Edinburgh, Scotland.

The entire reactor core is encased in a large, thick-walled casing known as the pressure vessel. Cooling water is forced through this vessel, via side-mounted nozzles, to carry heat from the reactor core to the rest of the plant. The control rods   enter the reactor vessel from the top; in-core instrument wiring enters the vessel from below. The diagram you see at left is an actual layout diagram for the core at TMI, showing locations of control rods, inlet and outlet nozzles, and instrumentation.

Note that depicted on the diagram are several neutron detectors, which are used to measure reactor power. The amount of neutron activity in the core is directly and reliably proportional to the thermal power the reactor is producing, so by monitoring neutron flux we can keep tabs on the reactor's heat output. The instruments are in three ranges because no one instrument could be accurate over the wide range of power levels the reactor covers during startup and shutdown. The source range instrument is used at extremely low power levels, primarily when the reactor is shut down. The power range instrument covers levels found when the reactor is operating at high power. The intermediate range instrument covers levels in between the other two instruments.

Three Mile Island Yesterday to Today

On March 28, 1979 equipment failures and human error at Three Mile Island Unit 2 nuclear power plant caused the worst nuclear accident in U.S. history.  No one was injured, but the partial meltdown at Three Mile Island, and the far worse meltdown and explosion at Chernobyl seven years later, scared Americans about the dangers of nuclear power. Not a single plant has been ordered since 1973.

Nuclear power industry engineers have designed a new generation of nuclear plants.  Three simpler -- and therefore cheaper and safer -- versions of the power plants currently in use have been approved by the Nuclear Regulatory Commission (NRC), a crucial vote of confidence for any interested utility.

There's renewed interest, but people are still skeptical that the public will allow nuclear [plants] to be built again. Even if a utility decided to build a reactor tomorrow, it would take a snag-free minimum of six to 10 years to bring it on line. The private investor will always take the lowest-risk, highest-return option, which, for now, is still gas generation.

U.S. utilities in 31 states operate 103 commercial reactors, which provide about 20 percent of the nation's electricity. All U.S. plants are either "boiling water reactors" or "pressurized water reactors" that use uranium-rich fuel rods in a reactor core to create a controlled nuclear chain reaction. The resulting heat changes water into steam that drives the turbo-generators. "Control rods," usually made of boron, are inserted or withdrawn from the core to regulate the pace of the reaction by soaking up excess neutrons.

In the meantime, the industry prepared three new reactor designs and obtained NRC certification for them. The object was standardization. If you can build in one place on an assembly line, it's much, much cheaper.  The three designs -- one by General Electric and two by Westinghouse -- are based on traditional technology. GE simplified safety systems, reduced the amount of hardware and made the plant easier to operate.

GE has built two 1,350-megawatt "Advanced Boiling Water Reactors" in Japan and has six under construction: four in Japan and two in Taiwan. The two operating plants took four years and three months to build. 

Neither of Westinghouse's two designs, both pressurized water reactors, has been built. The System 80-Plus, also 1,350 megawatts, is projected to be South Korea's next-generation reactor and existing plants there have incorporated features of the new system.

The Westinghouse 600-megawatt "AP600" departs more from tradition because it incorporates "passive" safety features based on gravity and other natural forces. Many safety devices are activated without human intervention.

Obtaining certification for the passive safety system was "a fundamental issue" for Westinghouse because the system will allow off-site, modular construction that can be finished in three years.

A new type of plant (Pebble Bed Modular Reactor) (not yet NRC-approved) that uses hundreds of thousands of billiard-ball-sized "pebbles" of nuclear material instead of a conventional reactor core. It does not have enough radioactive fuel in a confined space to generate the temperatures necessary for the pebbles to explode. In theory, it is meltdown-proof.

The only truly innovative design on the horizon for the U.S. market is the pebble bed reactor. Instead of fuel rods, the pebble bed reactor uses tiny particles of uranium dioxide encased in layers of graphite and silicon carbide and shaped into spheres. These pebbles -- 320,000 of them -- are poured into a 65-foot cylindrical hopper that is lined with graphite bricks and has a hollow column in the middle. The shape, called an annulus, is like an elongated angel food cake mold.

Once in place, the pebbles initiate a chain reaction. But instead of making steam, the plant pumps helium into the top of the hopper and extracts the heated gas at the bottom, where it drives the turbines.

To shut down the reactor, control rods are inserted through conduits in the graphite bricks. Because the rods cannot run straight through the pebble bed, the reactor must be small -- 110 to 130 megawatts, vs. 1,000 megawatts or more for a water reactor. But its proponents see small size as an advantage.

You can build it in a modular fashion and locate it close to transmission lines where you need generation.  Smaller makes sense for utilities reluctant to make large investments.

What's best: Spend $3 billion, get the plant in five or six years, or $100 or $200 million and get it in 2 1/2 to three years? The idea is to build a lot of them quickly and get economies of scale that way.

A joint venture that the South African utility Eskom, British Nuclear Fuel and the South African government, is planning to build a prototype in South Africa and will seek NRC authorization to build a plant in the United States. But the company and the NRC agree it could not come on line before 2007.  Source: Washington Post, Dec 29, 2002 (Edited)