An explosion at the Fukushima Dai-ichi nuclear plant in Japan today raised fears of a nuclear meltdown.

Although nuclear disasters are rare, the few that have occurred echo in the public consciousness. Below are brief summaries of two of the most well-known, with supporting links to more information about the incidents.

Three Mile Island, March 1979

A partial reactor meltdown at this Pennsylvania power plant caused a release of radioactive material. Despite the leak, no deaths resulted in the incident, although the cleanup took years. A website created by Dickinson College offers a history of the Three Mile Island emergency at threemileisland.org.

Chernobyl, April 1986

Twenty five years ago, an explosion at a Ukrainian nuclear power plant caused possibly the worst disaster in the nuclear power industry’s history.

The accident destroyed a reactor at the plant, resulting in the deaths of about 30 people who worked at the facility or responded to the incident. More than a hundred others suffered from high levels of radiation.

The effects of Chernobyl lasted long after the initial explosion. Officials evacuated more than 220,000 residents from Belarus, the Russian Federation, and Ukraine. More than 6,000 incidents of thyroid cancer were measured in children and adolescents exposed from those three areas, according to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).

As bad as Chernobyl was, there are signs of slow healing at the site. The Ukrainian government announced it plans to reopen the 30-mile radius that was sealed around the Chernobyl plant to visitors this year.