Nuclear Reactors Health Physics Society - Power Reactor Section Radiation Science Education

Location of Operating Nuclear Reactors

Think of a Tea Kettle The fission process creates heat that produces steam in a secondary water system. The steam turns a turbine-generator which produces electricity.

Three Barriers to Contain Radiation

Defense In Depth 48” concrete containment building 35” concrete shield 8” steel reactor vessel solid nuclear fuel inside steel tubes

How Used Fuel is Removed

What Happens to Used Fuel? Nuclear reactors split atoms of uranium which creates heat. This process is called fission. Uranium in a nuclear reactor comes in the form of ceramic pellets. Only one of the uranium isotopes fission, U-235. New fuel contains about 5% U-235, the rest is U-238. When most of the U-235 has split, the used-up or “spent fuel” is stored in a large pool to cool off.

Dry Cask Storage After the fuel has “cooled”, it is moved into concrete casks. Eventually, the fuel will be sent to Yucca Mountain for permanent disposal deep under ground.

Transportation Safety A 120-ton locomotive, speeding at 80 miles an hour, crashed broadside into a container on a flatbed. The impact demolished the train, but hardly dented the container.

Transportation Container Used nuclear fuel: ceramic pellets encased in steel tubes. Used nuclear fuel cannot explode. Used nuclear fuel does not burn.

Yucca Mountain Volcanic eruptions created Yucca Mountain about 10 million years ago. Over the ages, layers of volcanic ash compressed and consolidated into a hard rock called tuff. There is very little rainfall, most of which quickly runs off the surface or evaporates. The water table under Yucca Mountain is extremely deep.

Permanent Disposal Yucca Mountain is federally owned land that borders the Nevada Test Site. More than 900 atomic weapon blasts have been conducted at the Nevada Test Site, mostly underground. $2 billion dollars have been spent on scientific investigation of the geology and hydrology of the site. Spent fuel will be stored 1000 feet below under ground, 800 feet above the water-table, protected by corrosion-resistant containers.