TOKYO -- Japan's efforts to decrease its stockpiles of plutonium -- material that can be used to produce nuclear weapons -- have failed to appease the international community, particularly the United States.
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Thomas Countryman, who served as assistant secretary of state for international security and nonproliferation in the U.S. administration of former President Barack Obama, has urged Japan to clarify how it will reduce its stockpiles of plutonium.
During a symposium in Tokyo in June, Countryman emphasized the United States has urged Japan to explain its reduction methods, adding that the current government of President Donald Trump is continuing to press Tokyo for such explanations.
In 1993, when Japan began to disclose the amount of plutonium it possessed, the volume stood at 10.8 metric tons. However, the figure increased more than four-fold to 47.3 tons by the end of 2017. The amount is feared to further increase in the future as Japan is approaching the completion of a spent nuclear fuel reprocessing plant in Rokkasho, Aomori Prefecture, slated for 2021.
Tokyo has explained that the country possesses plutonium mainly to be used as fuel at nuclear plants.
Addressing the situation, Yoshiaki Oka, chairman of the government's Japan Atomic Energy Commission (JAEC), summoned executives of the Federation of Electric Power Companies of Japan (FEPC) in charge of nuclear power in March and conveyed the government's concerns about the international community's reaction to an increase in the amount of plutonium that Japan stockpiles.
"We are facing a serious problem internationally. We're under pressure from the United States to provide a convincing explanation," Oka told FEPC executives.
Japan's wariness over the U.S. reaction to Tokyo's growing stockpiles stems from the automatic extension of a bilateral nuclear agreement that has served as the basis for Tokyo's push for a nuclear fuel cycle policy, in which spent nuclear fuel is reprocessed and reused at such power stations.
Since India's first nuclear test in the 1970s, the international community has been wary of nuclear substances and atomic energy-related technologies. Japan, which lacks resources, has refused to compromise on the reprocessing of spent nuclear fuel to sustain its nuclear fuel cycle project.
The United States agreed that Japan would continue reprocessing spent fuel under the bilateral nuclear agreement that went into force in 1988. Tokyo is the only non-nuclear weapons power allowed to reprocess spent fuel under an agreement with Washington as an exception.
The agreement was automatically extended on July 17 this year, 30 years after it came into force. However, the renewed accord can now be scrapped if either Japan or the United States declares an end to the pact six months prior.
Since the agreement has become legally fragile, Japan has had no choice but to respect the U.S. position of demanding that Japan decrease its stockpiles of plutonium. The United States also fears that other non-nuclear powers could demand exceptional treatment like that given to Japan.
In response to such concerns, the Diet in 2016 enacted the Spent Nuclear Fuel Reprocessing Fund Act to increase the national government's involvement in spent nuclear fuel processing. Noting that plans to operate reprocessing plants must be approved by the economy, trade and industry minister under the legislation, officials explain that the national government can supervise such projects to prevent the country's stockpiles of plutonium from increasing.
The government attempted to use this framework to convince the international community, but was unsuccessful, a senior official of the Cabinet Office said. "The law doesn't explicitly state that the stockpiles will be slashed. Relevant provisions are vague. The law failed to convince Washington. Therefore, we implemented additional measures," said the official.
The deadlock in Japan's nuclear fuel cycle policy has been part of the problem. In 2016, the government decided to decommission the prototype fast-breeder nuclear reactor Monju in Fukui Prefecture -- the core of the fuel cycle -- because it had hardly been in operation due to a string of technical issues and accidents.
For now, the government plans to process used fuel into mixed oxide (MOX) fuel -- usually consisting of plutonium blended with natural uranium -- and use such fuel at nuclear plants.
Such power generation began in 2009, but only four nuclear reactors that can use MOX fuel have so far been put into operation because safety standards have been stiffened following the outbreak of the Fukushima nuclear disaster in March 2011.
The international community, especially the United States, has expressed growing concerns that Japan's stockpiles of plutonium could further increase following the start of operations at the Rokkasho reprocessing plant. A safety inspection by the Nuclear Regulation Authority on the plant has entered a final phase. The current stockpiles have remained high because the material has not been steadily consumed in Japan.
(Japanese original by Ei Okada, Science & Environment News Department)