Question: How bad was the nuclear accident that Wendall Woodbury reported on?

Context paragraphs:
Leland Powers School: The Leland Powers School, also known as the Leland Powers School of Communication, Leland Powers School of Radio, Theatre, and Television, Leland Powers Theatre School, the Leland Powers School of Expression, Leland Powers School of the Spoken Word, and originally called the Leland Powers School of Elocution, was originally located in the Fenway neighborhood of Boston, Massachusetts, and later in Brookline, Massachusetts.  Speaker and author Leland Powers founded the school in 1904.  The school educated several notable speakers and authors of the early 20th century, including drama educator T. Earl Pardoe, actress Reta Shaw, and journalist Wendall Woodbury.

Kyshtym disaster: The Kyshtym disaster was a radioactive contamination accident that occurred on 29 September 1957 at Mayak, a plutonium production site in Russia for nuclear weapons and nuclear fuel reprocessing plant of the Soviet Union.  It measured as a Level 6 disaster on the International Nuclear Event Scale (INES), making it the third-most serious nuclear accident ever recorded, behind the Fukushima Daiichi nuclear disaster and the Chernobyl disaster (both Level 7 on the INES).  The event occurred in Ozyorsk, Chelyabinsk Oblast, a closed city built around the Mayak plant, and spread hot particles over more than 20,000 sqmi , where at least 270,000 people lived, with 300 immediate deaths among the villagers nearby.  Since Ozyorsk/Mayak (named Chelyabinsk-40, then Chelyabinsk-65, until 1994) was not marked on maps, the disaster was named after Kyshtym, the nearest known town.

Andreev Bay nuclear accident: The Andreev Bay nuclear accident took place at Soviet naval base 569 in February 1982.  Andreev Bay is a radioactive waste repository, located 55 km northwest of Murmansk and 60 km from the Norwegian border on the western shore of the Zapadnaya Litsa (Kola Peninsula).  The repository entered service in 1961.  In February 1982, a nuclear accident occurred, a radioactive water release from a pool in building #5.  Cleanup of the accident took place from 1983 to 1989.  About 700,000 tonnes of highly radioactive water leaked into the Barents Sea during that time period.  About 1,000 people took part in the cleanup effort.  Vladimir Konstantinovich Bulygin, who was in charge of the naval fleet's radiation accidents, received the Hero of the Soviet Union distinction for his work.

Nuclear Accident Magnitude Scale: The Nuclear Accident Magnitude Scale (NAMS) is a scale to measure the severity of a nuclear accident.  It was proposed by the British nuclear safety expert David Smythe in 2011 as a response to the Fukushima Daiichi nuclear disaster, where the conventional International Nuclear Event Scale was used in a confusing manner.  Furthermore, it wants to bridge the various shortcomings of INES.

Wendall Woodbury: Wendall J. Woodbury (June 20, 1942 – October 20, 2010) was an American television journalist and news anchor.  He spent much of his career as a reporter for WGAL-TV in Lancaster, Pennsylvania, from 1968 until his retirement from broadcast news in 1992 as a feature reporter.  He was known for a series of segments called "Wendall's World" while at WGAL.  Woodbury was the first television anchor in the United States to report on the Three Mile Island accident as the story broke in 1979.

Phoenix Rising (novel): Phoenix Rising is a 1994 book by Karen Hesse.  It is a realistic fiction book about a 13-year-old girl named Nyle and her grandmother, and how their lives are disrupted by a nuclear accident.  Everyone that lives anywhere near the accident suddenly has to wear masks, test everywhere for high levels of radiation, and watch everything they eat and drink to make sure it's not contaminated until the government gives the all clear.  Nyle and her grandmother live together on a farm in Vermont, near the nuclear plant in Cookshire.  She and her grandmother take in two evacuees from the accident.  The boy, 15-year-old Ezra Trent, absorbed a large amount of radiation and is very sick, yet there is no room in any of the hospitals for him.  His father had died less than a week ago at the time Nyle and her grandmother take them in, due to radiation poisoning.  Nyle is terrified to let herself care about him because she believes that if she lets herself care for him, she will end up losing him, just like her mother and grandfather.  He and his mother, Miriam Trent, end up staying in the back bedroom, which Nyle calls 'the dying room' because that is where her mother and grandfather had died when they were sick.  She pushes Ezra away, but they eventually end up growing closer as he gets better.

Igor Kostin: Igor Fedorovich Kostin (27 December 1936 – 9 June 2015) was one of the five photographers in the world to take pictures of the Chernobyl nuclear disaster near Pripyat in Ukraine, on 26 April 1986.  He was working for Novosti Press Agency (APN) as a photographer in Kiev, Ukraine, when he represented Novosti to cover the nuclear accident in Chernobyl.  Kostin′s aerial view of the Chernobyl nuclear power plant was widely published around the world, showing the extent of the devastation, and triggering fear throughout the world of radioactivity contamination the accident caused, when the Soviet media was working to censor information regarding the accident, releasing limited information regarding the accident on 28 April 1986, until the Soviet Union′s collapse in 1991.

Three Mile Island accident: The Three Mile Island accident occurred on March 28, 1979, in reactor number 2 of Three Mile Island Nuclear Generating Station (TMI-2) in Dauphin County, Pennsylvania, United States, near Harrisburg.  It was the most significant accident in U.S. commercial nuclear power plant history.  The incident was rated a five on the seven-point International Nuclear Event Scale: Accident with wider consequences.

Three Mile Island accident health effects: The health effects of the 1979 Three Mile Island nuclear accident are widely, but not universally, agreed to be very low.  The American Nuclear Society concluded that average local radiation exposure was equivalent to a chest X-ray, and maximum local exposure equivalent to less than a year's background radiation.  The U.S. BEIR report on the Biological Effects of Ionizing Radiation states that "[t]he collective dose equivalent resulting from the radioactivity released in the Three Mile Island accident was so low that the estimated number of excess cancer cases to be expected, if any were to occur, would be negligible and undetectable."  A variety of epidemiology studies have concluded that the accident has had no observable long term health effects.  One dissenting study is "A reevaluation of cancer incidence near the Three Mile Island nuclear plant" by Dr. Steven Wing of the University of North Carolina.  In this study, Dr. Wing and his colleagues argue that earlier findings had "logical and methodological problems" and conclude that "cancer incidence, specifically lung cancer and leukemia, increased following the TMI accident in areas estimated to have been in the pathway of radioactive plumes than in other areas."

Anti-nuclear power movement in Japan: Long one of the world’s most committed promoters of civilian nuclear power, Japan's nuclear industry was not hit as hard by the effects of the 1979 Three Mile Island accident (USA) or the 1986 Chernobyl disaster (USSR) as some other countries.  Construction of new plants continued to be strong through the 1980s and into the 1990s.  However, starting in the mid-1990s there were several nuclear related accidents and cover-ups in Japan that eroded public perception of the industry, resulting in protests and resistance to new plants.  These accidents included the Tokaimura nuclear accident, the Mihama steam explosion, cover-ups after accidents at the Monju reactor, and the 21 month shut down of the Kashiwazaki-Kariwa Nuclear Power Plant following an earthquake in 2007.  Because of these events, Japan's nuclear industry has been scrutinized by the general public of the country.

Supporting paragraphs: Wendall Woodbury Three Mile Island accident
Answer: the most significant accident