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JCO Criticality Accident and Local Residents:

Damages, Symptoms and Changing Attitudes

JCO Criticality Accident and Local Residents: Damages, Symptoms and Changing AttitudesKoichi Hasegawa & Yuko Takubo

Citizens' Nuclear Information Center June 2001 (52 pages)

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cf."Tokai nuke incident still shows afterglow" By Stephen Hesse(Japan Times)


  • Foreword
  • JCO Criticality Accident and Local Residents: Damages, Symptoms and Changing Attitudes
  • Afterword
  • Survey on Impacts of JCO Criticality Accident on Nearby Citizens
  • Appendix

CNIC has recently published an English translation of a field study conducted on the local residents living in the vicinity of the JCO plant. The study was conducted in February 2000, and was reported in Japanese in September 2000. This English version of the report includes up-dates, as well as graphs, tables, maps, and photos to supplement the findings.

The study consisted of multiple-choice questions, open questions, and a follow-up interview upon the collection of the survey forms by volunteers. Responses to the open questions and the interviews are referred to in the main article preceding the survey data section, which documents the full results of the multiple-choice questions.

The main results were: (1) Residents experienced physical abnormalities and mental symptoms. At the time of the survey, 35% of respondents living within a 2 km radius of the JCO plant complained of physical symptoms. (2) Residents had strong anxiety over the future effects from radiation on themselves and their family members. In addition, residents had concerns over future indirect effects from the accident. For example, a resident of Tokai Village living within a 350~500 m radius of JCO, stated: "I am worried that even if there were no physical damage, my children will be discriminated against in the future just because they lived near the JCO plant ... and will not be able to get married." (3) The lack of information was a factor of anxiety and dissatisfaction during and after the accident. Only 14.1% had accurate knowledge about the JCO plant, and 37.1% were not even aware of its existence. (4) On one hand, about 2/3 of the residents became critical of nuclear power. (5) But on the other hand, about half saw Tokai Village's future as "co-existing with the nuclear industry." (6) Even so, local residents are no longer interested in blindly accepting the national nuclear development plans. Over 60% of the residents felt that the siting of nuclear power facilities should be decided by referenda.

Reprinted with permission from Stephen Hesse,
The Japan Times Environmental Columnist
Column: Our Planet Earth
July 12, 2001


Tokai nuke incident still shows afterglow


Hisashi Ouchi died Dec. 21, 1999, less than three months after he and two colleagues set off a criticality accident at JCO Co. in the village of Tokai, Ibaraki Prefecture. Masato Shinohara died seven months later, also a victim of lethal radiation exposure. The third employee, Yutaka Yokokawa, was hospitalized for several months then released. He has not yet fully recovered.

Ouchi, Shinohara and Yokokawa are the most notable victims of the Tokai accident, but they are not the only ones. Thousands of others living in and around the village of Tokai and the town of Naka were affected.

There were other victims as well: Japan's naivete, its national denial that a nuclear accident could happen here; government and industry assurances that Japan's nuclear-power industry is safe; and trust in the nation's corporate and political leaders.

A May 27 plebescite in Kariwa Village, Niigata Prefecture, brought this new nuclear reality into high relief. Villagers were asked whether to allow Tokyo Electric Power Company (TEPCO) to use mixed uranium-plutonium oxide (MOX) fuel in a local reactor. Unlike traditional uranium-based fuels, MOX includes plutonium. Fifty-three percent of Kariwa villagers voted "No," rejecting the TEPCO proposal.

The tally was a shock because Kariwa is located in Japan's nuclear-power heartland. The town hosts seven reactors and about one in four households derives its principal income from nuclear power-related employment.

Criticality is a situation "in which a nuclear chain reaction becomes self-sustaining, [similar to] what occurs in a nuclear reactor," the late Dr. Jinzaburo Takagi wrote in his book, "Criticality Accident at Tokai-mura," published by the Citizens' Nuclear Information Center, a group he founded in 1975, and whose executive director he was from 1987-98. The criticality accident at Tokai "was as if a small, completely 'exposed' nuclear reactor had suddenly appeared in a conversion building of a nuclear fuel plant," explained Takagi, "a facility which does not have a nuclear reactor on site."

Tokai is located about 110 km northeast of Tokyo. At the time of the accident, JCO Co. was in the business of "uranium reconversion," a process in which enriched uranium is converted into uranium oxide for fabrication into fuel assemblies used in nuclear power plants. JCO had its manufacturing license revoked in March 2000; it is now dealing with a criminal case and compensation claims.

What effects did Japan's worst nuclear-power accident have on the lives, health, and thoughts of local residents? CNIC conducted a field survey of residents in Tokai and the neighboring town of Naka in February 2000.

The results of the survey were released in Japanese last year, and in English last month. "JCO Criticality Accident and Local Residents: Damages, Symptoms and Changing Attitudes" is an informative and readable 48-page report that takes a close look at the concerns and fears of 946 households, a sample of the 2,683 homes within a 2-km radius of the accident site.

Health and safety are primary concerns. Residents voiced "anxiety over delayed effects from radiation" (54.6 percent of respondents), and fears that "there might be another nuclear-related accident" (53.9 percent). One resident said, "I am (concerned) about my children's health -- whether they can have children even if they get married, and the possibility of having abnormal children." Ongoing health problems for some include headaches, weakness, tiredness and sleeplessness.

Some locals fear the discrimination experienced by the victims of Hiroshima and Nagasaki. "I am worried," one said, "that even if there [is] no physical damage, my children will be discriminated against in the future just because they lived near the JCO plant . . . and will not be able to get married."

The survey found that "close to 90 percent of the residents" hold the former Science and Technology Agency responsible for the accident and its effects. The agency, which was responsible for overseeing JCO Co., has since been incorporated into the Ministry of Education, Culture, Sports, Science and Technology. Sixty-six percent of the villagers voiced criticism of nuclear power and were critical of Japan building new nuclear plants.

About half of those interviewed saw their town "co-existing with the nuclear industry." Skepticism runs deep, however, and more than 60 percent of local residents felt the construction of future nuclear-power facilities should be decided by local referenda.

"The survey [is] extremely valuable for examining the long-term effects of the accident," says Gaia Hoerner, translator and editor of the report. "The results speak for themselves on the effects of the accident, and will greatly contribute to studies on the risks of nuclear power."

Time will tell what Japan's nuclear-power industry has learned. In the foreword to the report, Michiaki Furukawa, a nuclear chemist and professor emeritus at Nagoya University, writes, "The government recognized the seriousness of the accident and has been reforming laws and nuclear regulatory bodies to improve the administration of nuclear matters. However, the effectiveness of such reforms can only be evaluated after observing changes over a long period of time. While such reforms cannot have worsened the conditions at nuclear facilities, citizens must keep a watchful eye on whether the countermeasures implemented by the central government are adequate."

In the meantime, the report concludes, the government must "comprehensively review its energy policy -- with complete nuclear phaseout as one of the options."

A final thought before you crank up your air conditioner: Summer is the season for reactor mishaps. According to the most recent issue of CNIC's English newsletter, "Nuke Info Tokyo," there were 32 "significant incidents" at nuclear facilities in Japan last year, including radioactive leaks. Almost half of those were between June and August, and two-thirds were within a year of the Tokai criticality accident.

CNIC is a public-interest information service that provides information and public education on nuclear power and nuclear issues. For more information on CNIC e-mail or visit the Web site at

Stephen Hesse welcomes questions. and comments at

The Japan Times: July 12, 2001

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