View source for Monju Nuclear Power Plant

{{Short description|Closed nuclear power plant in Japan}}
{{Redirect|Monju|the discontinued limited express train service|Monju (train)}}
{{Infobox power station
| name               = Monju Nuclear Power Plant
| name_official      =
| image              = Monju.JPG
| image_caption      = Monju Nuclear Power Plant
| coordinates = {{coord|35|44|25|N|135|59|17|E|region:JP-18_type:landmark_source:dewiki|display=inline,title}}
| coordinates_ref    =
| country            = Japan
| location             = [[Tsuruga, Fukui|Tsuruga]], [[Fukui Prefecture]]
| status             = B
| construction_began = {{start date|1986|05|10}}
| commissioned       = August 29, 1995<br />May 6, 2010 (reactivated)
| decommissioned     = December 8, 1995 (suspended for 15 years)
| cost               =
| owner              =
| operator           = [[Japan Atomic Energy Agency]]
| ps_units_operational= 
| ps_units_uc  =
| ps_units_planned=
| ps_units_decommissioned  =1 × 280 MW
| np_reactor_type       = [[fast breeder reactor|FBR]]
| np_reactor_supplier   =
| ps_electrical_capacity = 280 MW
| ps_electrical_cap_fac    =
| website            =
| extra              =
}}

{{nihongo|'''Monju'''|もんじゅ|}} was a Japanese [[sodium-cooled fast reactor]], located near the [[Tsuruga Nuclear Power Plant]], [[Fukui Prefecture]]. Its name is a reference to [[Manjusri]]. Construction started in 1986 and the reactor achieved [[nuclear chain reaction|criticality]] for the first time in April 1994. The reactor has been inoperative for most of the time since it was originally built. It was last operated in 2010<ref name="jt-20140225">{{cite news |url=http://www.japantimes.co.jp/opinion/2014/02/25/commentary/time-to-shutter-monju/ |title=Time to shutter Monju |newspaper=The Japan Times |date=25 February 2014 |accessdate=4 May 2015}}</ref> and is now closed.

Monju was a [[sodium]] [[Nuclear reactor coolant|cooled]], [[MOX]]-fueled, loop-type reactor with three primary coolant loops, designed to produce 280&nbsp;[[Watt#Conventions in the electric power industry|MWe]] from 714&nbsp;[[Watt#Conventions in the electric power industry|MWt]]. It had a [[Breeder reactor#Conversion ratio, Breakeven, Breeding Ratio, Doubling Time, and Burnup|breeding ratio]] of approximately 1.2.<ref>{{cite web |url=http://www.jaea.go.jp/04/monju/EnglishSite/contents02-1.html |title=Basic specifications |accessdate=2013-05-16 |url-status=dead |archiveurl=https://web.archive.org/web/20130123183123/http://www.jaea.go.jp/04/monju/EnglishSite/contents02-1.html |archivedate=2013-01-23 }}</ref>
The plant is located on a site that spans 1.08&nbsp;km<sup>2</sup> (267 acres), the buildings occupy 28,678 m<sup>2</sup> (7 acres), and it has 104,680 m<sup>2</sup> of floor space.

An accident in December 1995, in which a sodium leak caused a major fire, forced a shutdown. A subsequent scandal involving a [[cover-up]] of the scope of the accident delayed its restart until May 6, 2010, with renewed criticality reached on May 8, 2010.<ref name="nei-20100304">{{cite news|url=http://www.neimagazine.com/story.asp?storyCode=2059044 |archive-url=https://archive.today/20130130012503/http://www.neimagazine.com/story.asp?storyCode=2059044 |url-status=dead |archive-date=30 January 2013 |title=Monju, modified |author=Tsutomu Yanagisawa |publisher=Nuclear Engineering International |date=4 March 2011 |accessdate=28 January 2012 }}</ref> In August 2010 another accident, involving dropped machinery, shut down the reactor again. As of June 2011, the reactor had only generated electricity for one hour since its first testing two decades prior.<ref name="TABUCHI">{{cite news|title=Japan Strains to Fix a Reactor Damaged Before Quake |first=Hiroki |last=Tabuchi |author-link=Hiroko Tabuchi |work=The New York Times |date=June 17, 2011 |url=https://www.nytimes.com/2011/06/18/world/asia/18japan.html?_r=1&pagewanted=all}}</ref>  As of the end of 2010, total funds spent on the reactor amounted to ¥1.08 trillion.  An estimated ¥160–170 billion would be needed to continue to operate the reactor for another 10 years.<ref>[[Kyodo News]], "[http://www.japantimes.co.jp/text/nn20120704f1.html Monju costs far surpass usual nukes]", ''[[Japan Times]]'', 4 July 2012, p. 3</ref> As of 2014, the plant had cost [[Japanese yen|¥]]1 trillion ($9.8 billion).<ref name="afp-20140207" />

A final decision on the project (e.g. to decommission or extend funding) was due by end 2016,<ref name="sciencemag-20160921">{{cite news |url=https://www.science.org/content/article/japan-likely-scrap-experimental-nuclear-power-reactor |title=Japan likely to scrap experimental nuclear power reactor |author=Dennis Normile |newspaper=Science |date=21 September 2016 |accessdate=3 December 2016}}</ref> and a decision to close the facility was made in December 2016.<ref>{{cite news|title=Japan cancels failed $9bn Monju nuclear reactor|url=https://www.bbc.com/news/world-asia-38390504|publisher=BBC|date=21 December 2016|accessdate=23 December 2016}}</ref><ref name="wnn-20161222">{{cite news |url=http://www.world-nuclear-news.org/NP-Japanese-government-says-Monju-will-be-scrapped-2212164.html |title=Japanese government says Monju will be scrapped |publisher=World Nuclear News |date=22 December 2016 |accessdate=23 December 2016}}</ref> In December 2017 the [[Japan Atomic Energy Agency]] applied for approval of its decommissioning plan by the [[Nuclear Regulation Authority]]. Decommissioning and dismantling are planned to be completed by 2047 and is expected to cost [[Japanese yen|¥]]375 billion.<ref name="nei-20171229">{{cite news |url=http://www.neimagazine.com/news/newsjapan-closes-ohi-12-and-monju-6014448 |title=Japan closes Ohi 1&2 and Monju |publisher=Nuclear Engineering International |date=29 December 2017 |accessdate=29 December 2017}}</ref>

==History==
===1995 sodium leak and fire===
On December 8, 1995, the reactor suffered an accident rated level 1 on the [[International Nuclear Event Scale]] (INES).<ref>{{Cite web |url=https://www.laka.org/docu/ines/event/579 |title=Laka foundation: INES 1 - Secondary sodium leakage in the prototype fast breeder reactor Monju |access-date=2021-11-18 |archive-date=2021-11-18 |archive-url=https://web.archive.org/web/20211118135359/https://www.laka.org/docu/ines/event/579 |url-status=dead }}</ref><ref>https://www.env.go.jp/en/chemi/rhm/basic-info/1st/pdf/basic-1st-06-02-04.pdf {{Bare URL PDF|date=March 2022}}</ref> Intense vibration caused a [[thermowell]] inside a pipe carrying sodium coolant to break, possibly at a defective [[welding|weld]] point, allowing several hundred kilograms of [[sodium]] to leak out onto the floor below the pipe. Upon contact with air, the liquid sodium reacted with oxygen and moisture in the air, filling the room with caustic fumes and producing temperatures of several hundred degrees Celsius. The heat was so intense that it warped several steel structures in the room. An alarm sounded around 7:30&nbsp;p.m., switching the system over to manual operations, but a full operational shutdown was not ordered until around 9:00&nbsp;p.m., after the fumes were detected. When investigators located the source of the spill they found as much as three tons of solidified sodium.

The leak occurred in the plant's secondary cooling system, so the sodium was not [[radioactive]]. However, there was massive public outrage in Japan when it was revealed that [[Power Reactor and Nuclear Fuel Development Corporation]] (PNC), the semi-governmental agency then in charge of Monju, had tried to cover up the extent of the accident and resulting damage. This coverup included falsifying reports and the editing of a videotape taken immediately after the accident, as well as issuing a [[gag order]] that aimed to stop employees revealing that tapes had been edited.<ref>{{cite news| title=REACTOR ACCIDENT IN JAPAN IMPERILS ENERGY PROGRAM| first=ANDREW | last=POLLACK| url=https://www.nytimes.com/1996/02/24/world/reactor-accident-in-japan-imperils-energy-program.html| work=New York Times| date=February 24, 1996}}</ref><ref>wise-paris.org [http://www.wise-paris.org/index.html?/english/ournewsletter/2/page7.html&/english/frame/menu.html&/english/frame/band.html Sodium Leak and Fire at Monju]</ref>

The official in charge of investigating the coverup, Shigeo Nishimura, committed suicide by leaping from the roof of a Tokyo hotel. Nishimura was deputy general manager of the general affairs department of the Power Reactor and the Nuclear Fuel Development Corporation, the Government concern that ran the country's prototype fast-breeder reactor.<ref>{{Cite news|agency=Reuters|date=1996-01-14|title=Japanese Suicide Linked To Nuclear Plant Leak (Published 1996)|language=en-US|work=The New York Times|url=https://www.nytimes.com/1996/01/14/world/japanese-suicide-linked-to-nuclear-plant-leak.html|access-date=2020-12-06|issn=0362-4331}}</ref> Officials said Nishimura was not involved in the cover-up but was distressed by evidence he had unearthed.

===2010 Restart===
[[File:Monju 04790003 (8389261826).jpg|thumb|Monju in 2007]]
On November 24, 2000, [[Japan Atomic Energy Agency]] announced their intention to restart the Monju reactor. This decision was met with resistance by the public, resulting in a series of court battles. On January 27, 2003, the [[Nagoya]] High Court's [[Kanazawa, Ishikawa|Kanazawa]] branch made a ruling reversing its earlier 1983 approval to build the reactor, but then on May 30, 2005, Japan's Supreme Court gave the green light to reopen the Monju reactor.

The nuclear fuel was replaced for the restart. The original fuel loaded was mixed plutonium-uranium oxide with plutonium content of around 15–20%, but by 2009, due to natural radioactive decay, the fuel had only half of the original [[plutonium-241]] content. This made achieving criticality impossible, requiring fuel replacement.<ref name=nei-20100304 />

The restart was scheduled for October 2008, having been moved back five months.<ref>World Nuclear News. [https://web.archive.org/web/20080516102504/http://www.world-nuclear-news.org/industry/Monju_enters_extended_testing_310807.shtml Monju enters extended testing]. Aug 31, 2007.</ref> A restart date of February 2009 was again delayed due to the discovery of holes in the reactor's auxiliary building; in August 2009 it was announced that restart might be in February 2010.<ref>Reuters. [https://web.archive.org/web/20100226143927/http://in.reuters.com/article/oilRpt/idINT5613620090812 Japan fast-breeder reactor may restart in Feb]. Aug 12, 2009.</ref>

In February 2010, JAEA obtained official approval to restart the reactor from the [[Japanese Government]]. The restart was definitely scheduled for the end of March.<ref>The Yomiuri Online. [http://www.yomiuri.co.jp/dy/national/20100223TDY01304.htm Monju reactor clears hurdle to restart]. Feb 23, 2010.  {{dead link|date=June 2016|bot=medic}}{{cbignore|bot=medic}}</ref> In late February, JAEA requested Fukui Prefecture and Tsuruga City for deliberations aimed at resuming test operation. Having obtained the go ahead from both entities, JAEA started criticality testing, after which it took some months before commercial operation could resume – as for any new nuclear plant.<ref>The Denki Shinbun. [http://www.shimbun.denki.or.jp/english/article/2010022604.shtml First step toward resuming test operation of Monju].{{Dead link|date=July 2011}} Feb 26, 2010. {{Dead link|date=July 2011}}</ref>

Operators started withdrawing control rods on May 6, 2010, marking the restart of the plant. The [[Fukui Prefecture]] governor, [[Issei Nishikawa]] asked the [[Ministry of Economy, Trade and Industry|METI]] for additional stimulus to the prefecture including an expansion of the [[Shinkansen]] in turn for the restart of the plant.{{clarify|date=December 2013}} Monju achieved criticality on May 8, at 10:36 AM JST. Test runs were to continue until 2013, at which point the reactor could have started to feed power into the electric grid, beginning "full fledged" operation.<ref name=mdn-20100508>{{cite news |url=http://mdn.mainichi.jp/mdnnews/news/20100508p2a00m0na014000c.html |title=Monju nuclear reactor reaches criticality after 14-year shutdown |newspaper=The Mainichi Daily News |date=8 May 2010 |archiveurl=https://web.archive.org/web/20100510063654/http://mdn.mainichi.jp/mdnnews/news/20100508p2a00m0na014000c.html |archivedate=2010-05-10}}</ref>

===2010 "In‐Vessel Transfer Machine" falling accident===
On August 26, 2010, a 3.3-[[metric ton|tonne]] "In‐Vessel Transfer Machine" fell into the reactor vessel when being removed after a scheduled fuel replacement operation.<ref>{{cite news|url=http://www.jaea.go.jp/04/turuga/jturuga/press/2010/10/p101001-2.pdf|script-title=ja:高速増殖原型炉もんじゅ燃料交換片付け作業中における炉内中継装置の落下について（中間報告）|date=1 October 2010|accessdate=14 March 2011|work=Turuga Head Office, JAEA|language=Japanese}}</ref>
On October 13, 2010, an unsuccessful attempt was made to retrieve the machine.<ref>[http://www.fukuishimbun.co.jp/localnews/nuclearpowermonjuresume/24207.html もんじゅ、装置回収また中断　ふたに引っ掛かる？] {{webarchive|url=https://web.archive.org/web/20110801084625/http://www.fukuishimbun.co.jp/localnews/nuclearpowermonjuresume/24207.html |date=2011-08-01 }}. October 14, 2010.</ref> The JAEA tried to recover the device used in fuel exchange but failed as it had become misshaped, preventing its retrieval through the upper lid.<ref name="dailydaily_110524">The Mainichi Daily News.
[http://mdn.mainichi.jp/mdnnews/news/20110524p2g00m0dm067000c.html Agency gears up to retrieve device fallen inside Monju reactor]. May 24, 2011.  {{webarchive |url=https://web.archive.org/web/20110607040254/http://mdn.mainichi.jp/mdnnews/news/20110524p2g00m0dm067000c.html |date=June 7, 2011 }}</ref>

The JAEA began preparatory engineering work on May 24, 2011 to set up equipment to be used to retrieve the IVTM that fell inside the vessel.<ref name="dailydaily_110524"/> The fallen device was successfully retrieved from the reactor vessel on June 23, 2011.<ref>[https://www.reuters.com/article/us-japan-nuclear-monju-idUSTRE75N0H320110624 Fallen device retrieved from Japan fast-breeder reactor] June 23, 2011.</ref>

===2012 Sodium-heater failure===
On Sunday 2 June 2012 the sodium heater, which keeps the sodium molten as a secondary coolant, ceased operating for half an hour from about 4:30&nbsp;p.m. The power supply was checked, but insufficient information in the service manual caused the heater to stop, causing a fall of about 40 C from 200 C of the sodium temperature. Under the internal rules of JAEA, the failure was regarded a too minor incident to report it to the authorities, but the next day the Nuclear Regulation Authority and local governments were informed about the incident. However it was not made public.<ref>The Mainichi Shimbun (08 June 2013) [https://archive.today/20130620221020/http://mainichi.jp/english/english/newsselect/news/20130608p2g00m0dm038000c.html Monju reactor's sodium heater temporarily halted by error]</ref>

===2013 New Director of the JAEA appointed===
On 31 May 2013 science and technology minister Hakubun Shimomura announced that Shojiro Matsuura, (77 years) the former chairman of the Nuclear Safety Commission, would be the next president of JAEA on Monday 3 June. In this function he would reorganize the JAEA, with safety as a top priority.

Former{{citation needed|date=June 2013}} functions of Matsuura:<ref>Japan Atomic Energy Agency: Board of directors [http://www.jaea.go.jp/english/about/board-of-directors.shtml board of directors June 2013]</ref>
* November 1998 President, JAERI (After experience as Vice President)
* April 2000 Chairman, Nuclear Safety Commission
Present functions: 
* November 2012 Chairman, Japan Nuclear Safety Institute
* June 2013 President, Japan Atomic Energy Agency <ref>The Mainich Shimbun (31 May 2013) [http://mainichi.jp/english/english/newsselect/news/20130531p2g00m0dm085000c.html Matsuura named to head Japan Atomic Energy Agency ] {{webarchive|url=https://archive.today/20130702215156/http://mainichi.jp/english/english/newsselect/news/20130531p2g00m0dm085000c.html |date=2013-07-02 }}</ref>

===Omitted safety inspections===
During safety inspections conducted by the NRA between 3 and 21 June 2013, it was revealed that the safety inspections on another 2,300 pieces of equipment had been omitted by JAEA.<ref>The Mainichi Shimbun (22 June 2013) [http://mainichi.jp/english/english/newsselect/news/20130622p2g00m0dm004000c.html Monju operator skipped inspections of another 2,300 devices] {{webarchive|url=https://web.archive.org/web/20130630013612/http://mainichi.jp/english/english/newsselect/news/20130622p2g00m0dm004000c.html |date=2013-06-30 }}</ref> In 2014 more uninspected equipment was discovered, and more than 100 improper corrections to inspection records found, leading to concerns that inspection reports were being falsified.<ref name=jt-20140411>{{cite news |url=http://www.japantimes.co.jp/news/2014/04/11/national/falsified-inspections-suspected-at-monju-fast-breeder-reactor/ |title=Falsified inspections suspected at Monju fast-breeder reactor |newspaper=The Japan Times |date=11 April 2014 |accessdate=4 May 2015}}</ref> Again in 2015 it was discovered that regular degradation assessments measuring the thickness of sodium cooling pipes had not been carried out since 2007.<ref name=jt-20150326>{{cite news |url=http://www.japantimes.co.jp/news/2015/03/26/national/science-health/maintenance-flaws-found-monju-reactor/ |title=More maintenance flaws found at Monju reactor |newspaper=The Japan Times |date=26 March 2015 |accessdate=4 May 2015}}</ref>

===Further incidents===
On 16 February 2012 NISA reported that a sodium-detector malfunctioned. About 3 p.m local time the alarm went off. Additionally, a ventilator that should cool a pipe stopped. According to NISA no leakage was found, and there was no damage to the environment. Repairs were planned.<ref>The Mainichi Daily News (17 February 2012)[http://mdn.mainichi.jp/mdnnews/news/20120217p2g00m0dm011000c.html Monju fast breeder reactor's sodium detector hits trouble] {{webarchive|url=https://web.archive.org/web/20120217191912/http://mdn.mainichi.jp/mdnnews/news/20120217p2g00m0dm011000c.html |date=2012-02-17 }}</ref>

On 30 April 2013 an operating error rendered two of the three emergency generators unusable. During the monthly testing of the emergency diesel generators, staff forgot to close six of the twelve valves they had opened before testing, releasing thick black smoke. JAERI reported it to the Nuclear Regulation Authority as a breach of security regulations.<ref>Japan Today (2 May 2013) [http://www.japantoday.com/category/national/view/black-smoke-detected-from-monju-reactor-during-test-operations Black smoke detected from Monju reactor during test operations]</ref>

On Monday 16 September 2013 before 3 a.m. the data transmission of the reactor stopped to the government's Emergency Response Support System. Whether this was caused by [[Typhoon Man-yi (2013)|Typhoon Man-yi]], the powerful typhoon that went through Japan that day, was unknown. At that moment it was not possible to restore the connection, because the reactor site in Tsuruga was inaccessible due to mudslides and fallen trees caused by the typhoon.<ref>The Mainichi Shimbun (16 September 2013) [http://mainichi.jp/english/english/newsselect/news/20130916p2g00m0dm035000c.html Data transmission from Monju reactor stopped] {{webarchive|url=https://web.archive.org/web/20130919085721/http://mainichi.jp/english/english/newsselect/news/20130916p2g00m0dm035000c.html |date=2013-09-19 }}</ref>

On August 3, 2016, it was discovered that an alert triggered on November 19, 2015, when the quality of the water in a spent nuclear fuel rod pool deteriorated, was ignored until April 2016 and rectified only the next month.<ref>The Mainichi Shimbun (3 August 2016) [http://mainichi.jp/articles/20160804/k00/00m/040/008000c もんじゅ 規定違反　水質悪化の警報、半年間放置]</ref>

==Developments since Fukushima-Daiichi accident in March 2011==

In September 2011 the ministry of education, science and technology asked for the fiscal year of 2012 only 20 to 30 percent of the budget to maintain and manage the Monju reactor for the year 2011. The uncertainty about Japan's future energy policy caused the ministry to conclude that the project could not proceed.<ref>JAIF (26 September 2011) [http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1317112036P.pdf Earth-quake-report 217: Japan to freeze fast-breeder reactor project] {{webarchive|url=https://web.archive.org/web/20120103100736/http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1317112036P.pdf |date=2012-01-03 }}</ref>

The test run of the reactor, in which the reactor's output would be raised to 40 percent of its capacity by the end of March 2012, was postponed on September 29, 2011, by the Japanese Government because the uncertainty over the future of nuclear energy. 
After the [[Fukushima Daiichi nuclear accident|accident in Fukushima]], the Atomic Energy Commission of Japan made a start with a review of Japan's long term energy policy. An outline of this policy would be published within 12 months. On September 30, officials of the Science and Technology ministry explained their decision not to start the test run at meetings in the city of 
[[Tsuruga]] and [[Fukui Prefecture]].<ref>JAIF(September 29, 2011)[http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1317264047P.pdf Earthquake-report 219: Japan to postpone test to restart Monju reactor] {{webarchive|url=https://web.archive.org/web/20111028153744/http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1317264047P.pdf |date=2011-10-28 }}</ref>

The local Fukui edition of the Asahi Shinbun reported on June 22, 2012 that the reactor would restart in July 2012.<ref>[http://mytown.asahi.com/fukui/news.php?k_id=19000141206220002 Asahi Shinbun Fukui local edition (July 4 2012)] {{webarchive|url=https://web.archive.org/web/20120712220510/http://mytown.asahi.com/fukui/news.php?k_id=19000141206220002 |date=2012-07-12 }}</ref>

After it was revealed in November 2012, that regular safety checks had been omitted, the [[Nuclear Regulation Authority]] ordered JAEA to change its maintenance rules and inspection plans. JAEA had failed to perform periodical safety checks on nearly 10,000 out of 39,000 pieces of equipment at the plant before the deadlines were met. Half May 2013 not all details were worked out, and under the rules set by the NRA, it was not allowed to change nuclear fuel rods or move the control rods. Therefore, the restart of the reactor was not permitted.<ref>The Mainichi Shimbun (13 May 2013) [http://mainichi.jp/english/english/newsselect/news/20130513p2g00m0dm075000c.html Nuclear authority not to allow restart of Monju reactor] {{webarchive|url=https://web.archive.org/web/20130617185835/http://mainichi.jp/english/english/newsselect/news/20130513p2g00m0dm075000c.html |date=2013-06-17 }}</ref>

On 16 May 2013 the NRA ordered JAEA President Atsuyuki Suzuki to comply with their decisions and planned a meeting on 23 May to explain their reasoning, making it very likely that the NRA would block the reactivation of the reactor. In reaction to this Suzuki told reporters, "It takes nearly one year for preparation and it is physically quite difficult (to restart the reactor before March 2013)."<ref>The Mainichi Shimbun(17 May 2013)[http://mainichi.jp/english/english/newsselect/news/20130517p2g00m0dm003000c.html Monju reactor unlikely to resume operations by next March: JAEA] {{webarchive|url=https://web.archive.org/web/20130618000410/http://mainichi.jp/english/english/newsselect/news/20130517p2g00m0dm003000c.html |date=2013-06-18 }}</ref> Because the criticism of the NRA on the sloppy safety controls Atsuyuki Suzuki resigned as President of JAEC on 17 May.{{citation needed|date=June 2013}} Although the resignation was accepted by the government, the move was a surprise, because on May 16 Susuki had spoken on a meeting in the Japanese parliament, the Diet, and to the NRA secretariat and had pleaded to restore the public's trust in the JAEC. The NRA commented, that Suzuki's resignation had not solved fundamental problems and that there was a need to restructure the JAEA as an organization.

Suzuki (born 1942) was an authority on the nuclear fuel cycle, and became President of the JAEA in August 2010. Before this he was a professor at the University of Tokyo and the chairman of the former Nuclear Safety Commission. Yonezo Tsujikura, vice president of the JAEA, served as acting president until a successor was chosen.<ref>The Mainichi Shimbun (17 May 2013) [http://mainichi.jp/english/english/newsselect/news/20130517p2a00m0na013000c.html Head of operator of trouble-plagued fast-breeder reactor resigns] {{webarchive|url=https://archive.today/20130702214603/http://mainichi.jp/english/english/newsselect/news/20130517p2a00m0na013000c.html |date=2013-07-02 }}</ref>

At the end of the fiscal year 2011, a budget of {{USD|29 million}} was requested to continue the Monju project. 
This money would cover the costs of maintenance and the costs of the test run, planned in the summer of 2012. 
On 20 November a seven-member Japanese government commission decided that the future of the Monju reactor should be thoroughly reviewed before a decision could be made for this 2012 budget. 
Some members of the commission thought that there would be little public support for restarting the fast breeder project, and that it was uncertain that the reactor could be taken into commercial service in 2050 as originally planned. 
Other members said that the Monju project should be stopped completely, and that all efforts should be put into the international fusion reactor project [[ITER]] instead. 
Decisions about the 2012 budget would be taken after the discussions in a panel of cabinet members about the nuclear policy of Japan, including the fast breeder reactor project, would be complete.<ref>NHK-world (20 November 2011) [http://www3.nhk.or.jp/daily/english/20111120_13.html Govt panel seeks to revise nuclear projects ] {{webarchive|url=https://web.archive.org/web/20111120193002/http://www3.nhk.or.jp/daily/english/20111120_13.html |date=2011-11-20 }}</ref>

Reports in 2012 indicated that plans to generate electricity at Monju would be abandoned, and the plant repurposed into a research centre for handling [[spent nuclear fuel]].<ref name=afp-20140207>{{cite news |url=http://phys.org/news/2014-02-japan-abandon-fast-breeder-reactor.html |title=Japan to abandon troubled fast breeder reactor |publisher=phys.org, Agence France-Presse (AFP) |date=7 February 2014 |accessdate=24 July 2014 |archivedate=29 July 2014 |archiveurl=https://web.archive.org/web/20140729103443/http://phys.org/news/2014-02-japan-abandon-fast-breeder-reactor.html |url-status=dead }}</ref><ref name=jt-20140207>{{cite news |url=http://www.japantimes.co.jp/news/2014/02/07/national/monju-may-be-relegated-to-site-for-waste-radiation-reduction-studies/#.Uve5i854C3k |title=Monju may be relegated to site for waste radiation-reduction studies |newspaper=The Japan Times |date=7 February 2014 |accessdate=9 February 2014}}</ref>

On 29 May 2013, the NRA announced that JAEA was prohibited from restarting the fast breeder reactor, describing the safety culture at the plant as "deteriorated", because the problems at the plant were not addressed, and the staff were aware of the delayed inspections. The NRA said that before it could plan a restart of the reactor, JAEA must allocate appropriate funds and human resources to rebuild a maintenance and management system to prevent the recurrence of coolant leakages and other problems. The NRA also announced that an assessment would be made of whether geologic faults at the location of the Monju facility are active. It had similar plans for surveys at six facilities all over Japan.<ref>{{cite web |title=Monju to stop restart |url=http://fukushima-is-still-news.over-blog.com/article-monju-to-stop-restart-118169254.html |website=fukushima-is-still-news.over-blog.com/ |accessdate=28 July 2014 |archiveurl=https://web.archive.org/web/20140810140624/http://fukushima-is-still-news.over-blog.com/article-monju-to-stop-restart-118169254.html |archivedate=10 August 2014 |date=30 May 2013 |quote=Monju operator ordered to stop restart preparation, Regulators effectively ban Monju reactor from restarting |url-status=dead }}</ref>

On 2 March 2015 Noboru Hirose, a senior NRA official, told NHK<ref>{{cite web |url=http://www3.nhk.or.jp/nhkworld/english/news/20150302_22.html |title=Lifting of Monju operation ban uncertain - News - NHK WORLD - English |accessdate=2015-03-04 |url-status=dead |archiveurl=https://web.archive.org/web/20150402102915/http://www3.nhk.or.jp/nhkworld/english/news/20150302_22.html |archivedate=2015-04-02 }}</ref> at the beginning of a 3-week regular safety check that he could not say when test runs would be permitted to start. 
He would first need to examine how safety checks are conducted and whether adequate measures are in place to avoid a repeat of earlier problems.
JAEA had hoped the ban would be lifted by the end of March 2015.

==Seismic research in 2011, 2012 and 2013==
On 5 March 2012 a group of seismic researchers revealed the possibility of a 7.4M (or even more potent) earthquake under the Tsuruga Nuclear Powerplant. Before this date the Japanese governmental Earthquake Research Committee and Japan Atomic Power had calculated that the Urasoko fault under the plant, combined with other faults connected to it, was around 25&nbsp;km long. and could cause a 7.2M quake and a 1.7 meter displacement. On top of this, the presence of the oceanic faults were not taken into account by NISA and JAP in the assessment of the safety of the Tsuruga nuclear power plant.

Analysis of sonic survey and other data provided by Japan Atomic Power analysed by a panel of experts of Nuclear and Industrial Safety Agency showed the presence of multiple faults existing within 2 to 3&nbsp;km from the [[Urasoko fault]]. According to Sugiyama, a member of this group of scientists, these faults were highly likely to be activated together, and this would extend the length of the Urasoko fault to 35&nbsp;km.

Computer simulations calculating the length of a fault based on its displacement, showed the Urasoko fault to be 39&nbsp;km long, a result close to the length estimated by the sonic survey data, and the fault could cause some 5 meter displacement when activated together with other faults.

Yuichi Sugiyama, the leader of this research group of the National Institute of Advanced Industrial Science and Technology, warned that – as other faults on the south side of the Urasoko fault could become activated together – "The worst case scenario should be taken into consideration"

According to the experts there were many other faults located under one reactor on the west side of the Urasoku fault that could move also simultaneously. If this would be confirmed, the location of the Tsuruga nuclear plant would be disqualified.<ref>The Mainichi Shimbun (5 March 2012)[http://mdn.mainichi.jp/mdnnews/news/20120306p2g00m0dm081000c.html Fault under Tsuruga nuclear plant could trigger M7.4 quake: research] {{webarchive|url=https://web.archive.org/web/20120307172308/http://mdn.mainichi.jp/mdnnews/news/20120306p2g00m0dm081000c.html |date=2012-03-07 }}</ref>

On 6 March 2012 NISA asked Japan Atomic Power Co. to reassess the worst-case scenario for earthquakes at the [[Tsuruga Nuclear Power Plant]]. What damage this could do to the buildings on the site, because the Urazoko fault, running around 250 meters from the reactor buildings, could have a serious impact on the earthquake resistance of the power plant. NISA was also planning to send similar instructions to two other nuclear power plant operators in the Fukui area: [[Kansai Electric Power Company]], and [[Japan Atomic Energy Agency]]. Because the [[Mihama Nuclear Power Plant]] and the Monju fast breeder reactor could also be affected by a possible earthquake caused by the Urazoko fault.<ref>The Mainichi Shimbun (7 March 2012) [http://mdn.mainichi.jp/mdnnews/news/20120307p2g00m0dm051000c.html Quake severity estimate for Tsuruga nuclear plant to be reassessed] {{webarchive|url=https://web.archive.org/web/20120308172342/http://mdn.mainichi.jp/mdnnews/news/20120307p2g00m0dm051000c.html |date=2012-03-08 }}</ref>

On 17 July 2013 a commission of five experts led by NRA commissioner Kunihiko Shimazaki started the investigations on the geological activity of 8 zones of crushed rock under the reactor. Whether these old [[Fault (geology)|faults]] could move in conjunction with the [[active fault]] situated half a kilometer from the reactor site, and would constitute a hazard for the reactor safety. One of the experts, Chiba University professor Takahiro Miyauchi,<ref>The Mainichi Shimbun (19 July 2013) [http://mainichi.jp/english/english/newsselect/news/20130719p2a00m0na014000c.html Govt's nuclear fuel cycle policy teeters on edge as onsite Monju inspection completed] {{webarchive|url=https://archive.today/20130721081730/http://mainichi.jp/english/english/newsselect/news/20130719p2a00m0na014000c.html |date=2013-07-21 }}</ref> did not take part in the two-day survey, but would visit the site afterwards.<ref>The MainichiShimbun (17 July 2013) [http://mainichi.jp/english/english/newsselect/news/20130717p2g00m0dm062000c.html Panel starts investigation on geologic faults at Monju reactor site] {{webarchive|url=https://archive.today/20130717145942/http://mainichi.jp/english/english/newsselect/news/20130717p2g00m0dm062000c.html |date=2013-07-17 }}</ref> On Thursday 18 July Kunihiko Shimazaki told reporters, that his team could not yet reach a conclusion, further research was needed. Another acoustic survey of the grounds was planned by Japan Atomic Energy Agency and a geological examination to determine the age of the clay and stones in the faults. This could take a couple of months to finish, The assessment was planned at the end of August 2013.<ref>The Mainichi Shimbun (19 July 2013) [http://mainichi.jp/english/english/newsselect/news/20130719p2g00m0dm040000c.html Conclusion on faults under Monju reactor will take time: survey team] {{webarchive|url=https://archive.today/20130719042537/http://mainichi.jp/english/english/newsselect/news/20130719p2g00m0dm040000c.html |date=2013-07-19 }}</ref>

==Decommissioning plans==

On 21 October 2011 the Japanese government appointed a commission to study ways to cut wasteful expenditures, one possibility being decommissioning the Monju prototype fast breeder reactor. The Government Revitalization Unit took up this issue, because the calls to abolish this reactor were growing after the nuclear accident at Fukushima. As the accident at the Fukushima Daiichi power plant made it difficult, if not impossible, to build new nuclear power plants, the government panel would also review subsidies for localities with atomic power plants as well as functions of related entities such as the Japan Atomic Energy Agency.<ref>Mainichi Japan (22 October 2011) [http://mdn.mainichi.jp/mdnnews/news/20111022p2g00m0dm013000c.html Gov't cost-cutting unit to study Monju reactor's abolition] {{webarchive|url=https://web.archive.org/web/20111022184306/http://mdn.mainichi.jp/mdnnews/news/20111022p2g00m0dm013000c.html |date=2011-10-22 }}</ref>

On 27 November, after a visit to the plant, nuclear disaster minister Goshi Hosono said that scrapping the Monju-fast-breeder reactor was an option that would be given serious thought. Politicians and private sector experts of the ruling Democratic Party of Japan made proposals for a thorough operational and budgetary review in the government's energy policy screening session earlier in the week before his visit.<ref>The Mainichi Daily News (28 November 2011) [http://mdn.mainichi.jp/mdnnews/news/20111128p2g00m0dm010000c.html Gov't to consider scrapping of Monju reactor as option: Hosono] {{webarchive|url=https://web.archive.org/web/20111201004058/http://mdn.mainichi.jp/mdnnews/news/20111128p2g00m0dm010000c.html |date=2011-12-01 }}</ref>

On 21 December 2016, the Japanese government confirmed the closure and decommissioning of the Monju reactor, with the suggestion that this would cost at least ¥375 billion.<ref>{{cite web | last =| first =  | authorlink =  | vauthors =  | date = 21 December 2016 | url = http://www.japantimes.co.jp/news/2016/12/21/national/monju-prototype-reactor-key-cog-japans-nuclear-energy-policy-scrapped/#.WGJYPLaLSV5
 | title = Monju prototype reactor, once a key cog in Japan's nuclear energy policy, to be scrapped | format =  | work = [[The Japan Times]] | pages =  | language =  | accessdate = 27 December 2016 }}</ref>
The decommissioning of Monju is planned to take 30 years.<ref name=wnn-20161222/><ref name=wnn-20170616>{{cite news |url=http://www.world-nuclear-news.org/WR-Monju-decommissioning-plan-approved-1606174.html |title=Monju decommissioning plan approved |publisher=World Nuclear News |date=16 June 2017 |accessdate=20 June 2017}}</ref>
The Japanese regulator, the [[Nuclear Regulation Authority]], accepted the plan in March 2018. The phases of the plan are:<ref name=wnn-20180328>{{cite news |url=http://www.world-nuclear-news.org/WR-Regulator-approves-Monju-decommissioning-plan-2803185.html |title=Regulator approves Monju decommissioning plan |publisher=World Nuclear News |date=28 March 2018 |accessdate=30 March 2018}}</ref>
#transfer spent fuel to on-site storage pool by 2022 (completed 13 October 2022<ref name=wnn-20221021>{{cite news |url=https://www.world-nuclear-news.org/Articles/Defuelling-completed-at-Japan-s-Monju-reactor |title=Defuelling completed at Japan's Monju reactor |publisher=World Nuclear News |date=21 October 2022 |access-date=23 October 2022}}</ref>)
#liquid sodium coolant extracted
#equipment dismantled
#reactor building demolished and removed by 2047

==Other FBR programs in Japan==
Despite its intention to close the Monju facility, the Cabinet appeared to reaffirm its commitment to a fast breeder program of some kind, essential if Japan's stockpile of some 50 tonnes of plutonium is to be disposed of.<ref name="nikkei-asian-review-2016">{{cite news|url=http://www.japantimes.co.jp/news/2016/09/21/national/japans-cabinet-hold-meeting-decide-fate-monju-reactor/#.V-xcqmR97XE|title=Japan to scrap troubled ¥1 trillion Monju fast-breeder reactor|date=21 September 2016|newspaper=Japan Times|access-date=2016-09-29}}
</ref>

''[[Jōyō (nuclear reactor)|Jōyō]]'' is a test fast breeder reactor located in [[Ōarai, Ibaraki]]. The reactor was built in the 1970s for the purpose of experimental tests and the development of FBR technologies.

The successor to Monju was expected to be a larger demonstration plant to be completed around 2025, built by the newly formed [[Mitsubishi FBR Systems]] company.<ref>{{cite web|title=New fast breeder reactor for Japan |url=http://www.neimagazine.com/story.asp?storyCode=2036584 |publisher=Nuclear Engineering International |accessdate=16 March 2011 |date=6 June 2006 |url-status=dead |archiveurl=https://web.archive.org/web/20110613090433/http://www.neimagazine.com/story.asp?storyCode=2036584 |archivedate=13 June 2011 }}</ref> However, in 2014 Japan agreed to cooperate in developing the emergency reactor cooling system, and in a few other areas, with the French [[ASTRID (reactor)|ASTRID]] demonstration sodium-cooled fast breeder reactor, which was subsequently cancelled in August 2019.<ref name=bl-20140505>{{cite news |url=https://www.bloomberg.com/news/articles/2014-05-05/japan-to-work-with-france-on-future-fast-breeder-atomic-reactor |title=Japan to Work With France on Future Fast-Breeder Atomic |author=Tara Patel, Gregory Viscusi |publisher=Bloomberg |date=5 May 2014 |accessdate=3 December 2016}}</ref><ref name=mainichi-20161022>{{cite news |url=http://mainichi.jp/english/articles/20161022/p2a/00m/0na/005000c |title=France wants Japan to share 570 billion yen ASTRID reactor development cost |newspaper=The Mainichi |date=22 October 2016 |accessdate=3 December 2016}}</ref><ref name=reuters-20190830>{{cite news |url=https://www.reuters.com/article/us-france-nuclearpower-astrid/france-drops-plans-to-build-sodium-cooled-nuclear-reactor-idUSKCN1VK0MC |title=France drops plans to build sodium-cooled nuclear reactor |author=Geert De Clercq |publisher=Reuters |date=30 August 2019 |accessdate=15 January 2022}}</ref> As of 2016, France was seeking the full involvement of Japan in the ASTRID development.<ref name=mainichi-20161022/><ref name=asahi-20160922>{{cite news |url=http://www.asahi.com/ajw/articles/AJ201609220057.html |title=Ministries spar as Japan focuses on fast reactor project in France |newspaper=The Asahi Shimbun |date=22 September 2016 |accessdate=3 December 2016}}</ref>

==See also==
{{Portal|Japan|Energy|Nuclear technology}}
*[[Fast-neutron reactor]]
*[[Nuclear power in Japan]]
*[[Sanshiro Kume]]

==References==
{{Reflist}}

==External links==
*[https://web.archive.org/web/20071129121402/http://www.mext-monju.jp/takuhai/video/monju02.wmv Video explaining the Monju accident] {{in lang|ja}}
*[https://web.archive.org/web/20100315014618/http://www.jaea.go.jp/04/monju/EnglishSite/index.html Monju home page]
*[http://dotsub.com/films/videotape/index.php?autostart=true&language_setting=en_2524 Leaked video of the 1995 accident, with subtitles in 5 languages]

{{Nuclear power in Japan}}
{{Nuclear technology}}
{{Authority control}}

[[Category:1980s establishments in Japan]]
[[Category:Civilian nuclear power accidents]]
[[Category:Liquid metal fast reactors]]
[[Category:Nuclear power stations in Japan]]
[[Category:Tsuruga, Fukui]]