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Safecast Report2017: Part 2.1-Issues-at-Fukushima-Daiichi-final


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This is part 2.1 of the 2017 Safecast Report. It is a 66-page A4-size print-quality pdf that provides a detailed description of conditions at the damaged powerplant. Sections are devoted to the overall plans for decomissioning, the spent fuel pools, contaminated water issues, the search for melted fuel debris and plans for extracting it, and other issues of importance. It begins with an 8-page introduction that describes the available sources of information, official and otherwise, and their relative credibility.

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Safecast Report2017: Part 2.1-Issues-at-Fukushima-Daiichi-final

  1. 1. PART 2.1: SITUATION REPORT Issues at Fukushima Daiichi Nuclear Powerplant
  2. 2. 2 Part 2- Situation Report August 2017 A note before we start: The Fukushima crisis continues to evolve slowly in most respects compared to the urgent situation in 2011. It is less dynam- ic in terms of new developments which demand emergency action, but it is an ongoing situation with ongoing hazards and concerns. The passage of time — over six years at this point — means that a tremendous amount of information has accumulated about almost every aspect of the disaster and its aftermath. In some fortunate instances, ongoing research and debate has led to greater clarification of scientific and other issues, as more reliable and less uncertain data has superseded fuzzier early estimates. In other instances, time has brought us no closer to clear understanding. During the first year or two of the accident the information gaps were huge. Basic in- formation and data about fundamental issues regarding its impacts still needed to be collected and analyzed in order to answer the most pressing questions. In terms of scientific research, this phase is essentially over, and we are now grap- pling with the proliferation of expert stud- ies on nearly every aspect. We now know a lot about the accident, its causes, how much radiation was released and where it went, the scale of its initial impacts on people and the environment, and some inkling of what long-term effects we might reasonably expect. There are ar- eas where we are can identify a lack of scientific knowledge. There are constant surprises and unexpected findings. As in every year since the disaster unfolded, it is difficult to keep up with these changing circumstances and new information. While the core of Safecast’s work is making crowdsourced environmental monitoring data freely available online, we’ve also gathered a large store of data on issues such as the condition of the Fukushima Daiichi plant itself, the situa- tion for evacuees, environmental conse- quences of the accident, food risks, and health issues, which we share among ourselves and which help us focus our efforts. From the start we have made a point of talking to researchers regard- less of their ideological stance on nuclear power, and over the past several years have fielded countless questions and requests for data, which we’ve always tried to respond to quickly and positively. The robustness of this dialogue has also made it possible for us to seek expert advice and opinion on many related sub- jects, and to pass this knowledge on to our community as well. From time to time we have published in- depth blog posts on specific subjects, and made technical backgrounders available online. We have often point- ed researchers, journalists, and oth- ers towards these to help them get up to speed. Quite a lot of technical infor- mation and many scientific reports are discussed, sometimes heatedly, on the Safecast Radiation Discussion Google Group. Volume 1 of the Safecast Re- port, < cast-report/> released online in March 2015, was an attempt to make this kind of information more accessible. It was followed by Volume 2 in March 2016. You are now reading Volume 3, compiled in August 2017. The following Situation Report is an attempt to collate and sum- marize the most relevant, current, and accurate information we are aware of on the major aspects of the Fukushima disaster and make it available as a refer- ence for anyone who is interested or has a need to know. In the following sections
  3. 3. 3 we describe the current situation at the Fukushima Daiichi site itself, for the en- vironment in general, for food, and for people’s health, and cite our sources of information in each case. We strive for accuracy and readability, as well as com- pleteness, and rather than attempt to include every piece of information we’re aware of, we have prioritized presenting a coherent summary informed by what we know, which will point readers to where they can find more in-depth infor- mation to inform themselves. We provide extensive links to relevant documents wherever possible. Like the prior vol- umes, Volume 3 of the Safecast Report is intended to be a stand-alone document which avoids as much as possible requir- ing readers to refer to Volume 1 or 2 for important information. Relevant changes and new developments are noted, while some basic background and other infor- mation remains largely unchanged. Every aspect of this disaster is accompa- nied by controversy, and we try to guard against our own biases and strive to be as open and inclusive as possible. Some people will undoubtedly find that our in- formation in some places contradicts what they’ve read elsewhere. Others will feel we do not give sufficient weight to one opinion or another. We have con- centrated on finding the best-docu- mented sources, and have attempted to evaluate the evidence dispassionately. We welcome criticism, and urge anyone who would like to point out contradictory data not to hesitate to do so. As always we will welcome that input, and would be pleased with any feedback which will help us improve our efforts. About information sources The reliability of information has always been a major issue affecting public un- derstanding of the Fukushima disaster, and in fact the lack of reliable information during the early stages of the disaster was the reason Safecast was founded. Official statements concerning ambient radiation levels in the environment, and to a lesser degree soil contamination, can be crosschecked against citizen science and independent academic re- search in most cases. Radiation levels and impacts in the ocean, with the ex- ception of the immediate vicinity of Daii- chi, have been very well documented by independent researchers, in a way which provides a useful cross-check against of- ficial claims concerning releases of con- taminated water to the ocean, etc.. Food testing data from many independent groups is available in addition to that from the government. There has been little or no systematic third-party verification of the decontamination process itself, but radiation levels can be easily confirmed for most locations if desired. Verifying the health monitoring done by the national and Fukushima Prefecture governments presents a higher technical hurdle, but several well-done health screening pro- grams run by local governments as well as by community groups and founda- tions allow many useful comparisons to be made. But for understanding what’s happen- ing onsite at the Daiichi plant itself, we are forced to depend on data provided by TEPCO almost exclusively, much of it presented with an obvious PR spin. Because there is almost no independent verification of measurements and work onsite, TEPCO data has an inherent un- verifiability which in some cases can be significant. Safecast has consistently pushed for third-party verification of ra- diation monitoring at the Daiichi site and elsewhere, and while some TEPCO staff and gov’t agency employees have pri- vately agreed that it would be beneficial for everyone, including for TEPCO itself, to adopt this kind of policy, none of our
  4. 4. 4 proposals have been accepted so far. Other qualified groups and researchers we know have made similar proposals and have also been rebuffed. We won’t give up, and will continue to press for the inclusion of third-party monitoring as a matter of course. Transparency benefits all. Partly in response to this kind of criticism, in March 2015 TEPCO announced a new “disclosure” policy under which all on- site measurement data would quickly be made publicly available. As will be not- ed below, while this data can be helpful, and TEPCO seems to be taking their dis- closure mandate seriously, it is relatively hard to locate at first (see links below). TEPCO: Tepco Announces New Dis- closure Policy And Independent Audit Of Drainage Water Issue; Says Find- ings Will Be Public By End Of March; March 6, 2015 com/release/2015/1248564_6844.html Japan Today: TEPCO to make all data on radiation at Fukushima plant public Mar. 31, 2015 national/view/tepco-says-it-will-make- all-data-on-radiation-at-fukushima- plant-public?utm_campaign=jt_newslet- ter&utm_medium=email&utm_source=- jt_newsletter_2015-03-31_PM Asahi: TEPCO to come clean on radi- ation levels, allow checks by outside experts March 31, 2015 ter/fukushima/AJ201503310040 Most announcements and news articles about this disclosure policy note that TEPCO said it will allow regular checks by third parties. We can only confirm that this is happening for tests of water in- tended to be released into the ocean af- ter purification. The only third parties that have been approved for this testing to date are JAEA and the Japan Chemical Analysis Center (JCAS). JAEA is a gov- ernment agency, and the Japan Chem- ical Analysis Center, while independent, has close government ties. Both entities have the requisite technical capabilities and experience to do accurate testing of this sort, and we have seen no evidence that would suggest that their measure- ments are inaccurate. Nevertheless, as we said above, we think it is important to allow testing by more fully independent organizations and researchers. Since implementing this policy in March 2015, TEPCO has gradually expanded the data it has made available, and claims that all of its measurement data has been available online since August 2015. It es- timates that 70,000 items will be made available annually. Much of this takes the form of handwritten ledger notes which have been scanned, and it is very time consuming to review them. Almost all of it is in Japanese. Nevertheless, it will be very useful to researchers and others to have this information available. Up to date measurement data appears to be available for the following categories: Wa- ter treatment facilities; Tanks, Discharged water /Sprinkled water; Accumulated water/Contaminated water in the build- ings; Units1-4 facilities/Common facili- ties; Units 5,6 facilities; General facilities/ Whole site facilities /Others; Waste fluid/ Water used for Decontamination; Drain- age/River; Groundwater; Soil /Gravel / Gravel inside the Power Station; Hazard- ous materials; Outside Power Station: TEPCO Disclosure page (Japanese): planaction/disclosure/2015/01/index-j. html
  5. 5. 5 English index: planaction/disclosure/2015/04/images/ english_form.pdf In addition, beginning in 2015, TEPCO improved the accessibility of its overall monitoring results, and has made it pos- sible to choose reports in various catego- ries using a calendar interface: TEPCOMonitoringresultspage(English) ma-np/f1/smp/index-e.html Quite a lot of information related to the di- saster is made available by various Japa- nese Government agencies in download- able form, much of it in English. These efforts are poorly coordinated at best, and the content is often repetitive, with nearly identical information being pub- lished by different agencies, though often with minor differences which require vigi- lance to spot. The original sources for the information are usually cited somewhere, and while several agencies have the offi- cial power to conduct their own inspec- tions, in practice information regarding Fukushima Daiichi itself almost invariably comes from TEPCO. In the absence of adequate independent sources, we are forced to rely on official documents like these for much of the information we in- clude in Section 2.1, about the Daiichi site, and we attempt to highlight relevant caveats and uncertainties. While we also make use of official data in the sections on evacuees, environment, food, and health as well, much more independent information and research data is general- ly available for these. Official Reports The International Atomic Energy Agency (IAEA) plays a major role in the global gov- ernance of nuclear weapons and nucle- ar energy, and its actions (and inaction) have been key factors in the response to the Fukushima disaster. IAEA investiga- tion teams are given access to the Daiichi site regularly, and also evaluate TEPCO and government data, issuing periodic reports on their findings. IAEA publishes the reports it receives from TEPCO and Japanese Gov’t ministries on its Fukushi- ma Daiichi Status Updates page: fukushima/status-update These reports are generally brief, read- able summaries, and provide links to other relevant reports. They also include brief assessments of the information pro- vided. One of the most recent reports is from August 2017. Approximately 30 pages of summaries and links provided by the government are followed by 2 1/2 pages of commentary and critique from the IAEA: Events and highlights on the prog- ress related to recovery operations at Fukushima Daiichi Nuclear Power Sta- tion, August, 2017 events_and_highlights_august_2017.pdf This is actually a useful list of reports and findings from TEPCO and government sources, and includes recent information about the ocean, decontamination, food, etc. It’s important to keep in mind that participation in IAEA programs is volun- tary on the part of national governments, and though there are consequences for non-participation and non-compli- ance, the IAEA is given access at the behest of the government and only with its cooperation. The IAEA can request access to specific sites or to specif- ic information, but there are occasional signs that it doesn’t always get what it has requested. All of this must be kept in mind when reading and parsing IAEA
  6. 6. 6 reports, whose language is always ex- tremely formal and diplomatic. More reports related to the Fukushima acci- dent are available on the IAEA’s website : fukushima The IAEA issued its comprehensive re- port on the Fukushima Disaster in Au- gust, 2015: IAEA Releases Director General’s Report on Fukushima Daiichi Accident news/iaea-releases-director-gener- al%E2%80%99s-report-fukushima-daii- chi-accident It includes the Report by the Director General (about 220 pages), as well as five technical volumes, each with several electronic annexes. The Director Gener- al’s Report is divided into several sec- tions: » The accident and its assessment (how the accident progressed, how and where safety functions failed, contrib- uting human factors, etc) » Emergency preparedness and re- sponse (initial official responses in Japan, protective measures taken for emergency workers and the public, in- ternational response, etc) » Radiological consequences (environ- mental consequences, public expo- sure, health effects, etc) » Post-accident recovery (remediation and decontamination, on-site prepa- rations for decommissioning, commu- nity issues, etc) » The IAEA response to the accident (Initial activities, action plans devel- oped, cooperation, meetings and conferences, etc) » The technical volumes follow a similar breakdown: » Technical Volume 1/5 - Description and Context of the Accident » Technical Volume 2/5 - Safety Assess- ment » Technical Volume 3/5 - Emergency Preparedness and Response » Technical Volume 4/5 - Radiological Consequences » Technical Volume 5/5 - Post-accident Recovery. There are 40 downloadable files in all, and a printed version, with CD-ROM annexes, is also available. The Director General’s report section is also available in several languages, including Arabic, Chinese, French, Russian, Spanish and Japanese. The report is massive, in short, and we suspect that very few people have read more than a portion of it. We will refer to some of its relevant findings in Section 2.5: Health, and elsewhere, but won’t attempt to summarize the entire report. We will note that though it couched it in characteristically diplomatic language, the IAEA’s criticism of TEPCO and the Japanese government in this report is as scathing as we are ever likely to read from a UN agency. It is reasonable to ask why, of course, if the regulatory failures and lack of preparation for accidents were so extreme, the IAEA had not de- tected this prior to the accident and in- sisted that Fukushima Daiichi and other TEPCO nuclear powerplants be shut down until safety modifications had been made. I think the only answer for this is that the IAEA cannot enforce safety, can only recommend what it considers best practices, and that it is only given access to what the government wants it to see.
  7. 7. 7 We think the recognition of the huge con- sequences of this in case of Fukushima should by now be leading to calls for more effective and binding governance of nuclear energy worldwide. Such calls may be being made, and in April 2017, a law reforming nuclear inspections was passed by the Japanese Diet. This law, based on US precedent, specifically al- lows regulators to conduct unannounced inspections of nuclear plants and gives them unlimited access to data they re- quest. It will not come into effect until 2020, however, and it is unclear if it ap- plies to international bodies like the IAEA as well as to Japanese regulators. KYODO: Revised law enables surprise inspection of nuclear plants Apr. 08, 2017 al/revised-law-enables-surprise-inspec- tion-of-nuclear-plants The 2015 IAEA report includes discus- sion of volunteer efforts after Fukushi- ma, and Safecast is mentioned very positively in that context (see Tech- nical Volume 4, Annex III, p.23): cations/PDF/AdditionalVolumes/P1710/ Pub1710-TV4-Web.pdf While the full IAEA report was issued in August 2015, a draft of the Report by the Director General section was leaked online by Greenpeace in late May of that year: Greenpeace website IAEA report draft download page (Japanese): news/blog/dblog/iaeaweb/blog/53006/ Greenpeace also issued a critique of the report based on the leaked draft: Global/japan/pdf/IAEA analysis by GP 20150528.pdf Interestingly, TEPCO, in its first major progress report issued since the release of the IAEA report, agreed with IAEA crit- icism on all of the main points regarding inadequate preparation, complacency, underplaying tsunami risk, faulty safe- ty analyses, etc.. (see p. 71 of the text linked below). TEPCO enumerates the measures it has put in place to address these shortcomings, but while it may be possible to evaluate some of of the tech- nical aspects, we may never know which of those those rooted in corporate and political culture are actually being reme- died. Nuclear Safety Reform Plan - Progress Report (Including Progress on Safety Measures at Power Stations) (2nd Quar- ter, FY2015) November 20, 2015 corp-com/release/betu15_e/imag- es/151120e0102.pdf The 2015 IAEA report follows on others from UN agencies: WHO Preliminary dose estimation from the nuclear accident after the 2011 Great East Japan Earthquake and Tsu- nami, 2012 pub_meet/fukushima_dose_assess- ment/en/ WHO Health risk assessment from the nuclear accident after the 2011 Great East Japan earthquake and tsunami, based on a preliminary dose estimation, 2013 pub_meet/fukushima_risk_assess- ment_2013/en/
  8. 8. 8 UNSCEAR 2013 Report to the Gener- al Assembly, Volume I: Report to the General Assembly, Scientific Annex A: Levels and effects of radiation exposure due to the nuclear accident after the 2011 great east-Japan earthquake and tsunami, 2014 publications/2013_1.html A draft of the UNSCEAR report on Fukushima was also leaked in 2013 several months prior to release. Safe- cast made a summary critique of the UNSCEAR Fukushima report: scear-2013-fukushima-final-report-com- mentary-v02 The German branch of the International Physicians for the Prevention of Nuclear War (IPPNW) issued a critique of the UN- SCEAR report as well: min/user_upload/pdf/english/Akzente_ Unscear2014.pdf Dr. Keith Baverstock also published a strong critique of the UNSCEAR report, through the Japanese magazine Kaga- ku, focusing on structural issues within the organization and their implications: Kagaku_201410_Baverstock.pdf After its 2013 report was issued, UN- SCEAR experts continued to collect data on the Fukushima accident, reviewing more than 200 publications issued be- tween October 2012 and December 2015 (the 2013 report considered infor- mation available up to October 2012). UNSCEAR has issued two white papers to evaluate these new findings, one in late 2015, another in 2016. The 2015 white paper was based on evaluation of publi- cations available by Dec 2014. In it they examine new evidence related to four thematic subject areas: releases and dis- persion for the atmosphere and marine environment; evaluations of doses for the public and workers; health implications for the workers and the public; and dos- es and effects for non-human biota. They also directly address the critiques from Baverstock and IPPNW, among others: Developments Since The 2013 UN- SCEAR Report On The Levels And Ef- fects Of Radiation Exposure Due To The Nuclear Accident Following The Great East-Japan Earthquake And Tsunami, 2015 publications/Fukushima_WP2015.html A second white paper was issued in 2016, which examined new information available up to the end of 2015. UN- SCEAR notes that, “In principle, the scope of the second white paper was extended to include not only publica- tions in peer-reviewed journals, but also peer-reviewed conference papers, reports issued by regional/national in- stitutes/organizations, government de- partments/ministries, learned societies, utilities, and similar bodies, 7 reports issued by intergovernmental organiza- tions, and major compilations (and/or analyses) of data from official and other sources.” They add that, “In exceptional cases, the scope was extended to scientific reports issued by non-governmental or- ganizations.” In addition to the previous thematic areas covered, the transfer of radionuclides in terrestrial and freshwater environments was added as a new area of evaluation. The authors state that par- ticular effort was made to evaluate new information that might challenge their pri- or conclusions, but that while a number of areas where not enough research has
  9. 9. 9 been done were identified, they found nothing which significantly affected the main findings of the 2013 report. Developments Since The 2013 UN- SCEAR Report On The Levels And Ef- fects Of Radiation Exposure Due To The Nuclear Accident Following The Great East-Japan Earthquake And Tsunami, publications/Fukushima_WP2016.html Another notable recent publication from UNSCEAR is Sources, Effects And Risks Of Ionizing Radiation, 2016 (published in 2017). This is part of an ongoing series of major UNSCEAR reports about radiation hazards and impacts, and is intended to be an authoritative scientific under- pinning for radiation risk evaluation and international protection standards. While not intended to focus on Fukushima, many questions and findings that have emerged from this disaster are presented in the analyses. UNSCEAR: Sources, Effects And Risks Of Ionizing Radiation, 2016 (Published April 2017) publications/2016.html The Safecast Report, Part 2: Situation Report consists of five separate sections dealing with Fukushima Daiichi itself, Evacuees, Environment and Decontam- ination, Food, and Health. The file you are reading contains section 2.1- Issues at Fukushima Daiichi Nuclear Powerplant (FDNPP). In this and the subsequent sections, released separately, we begin with a general summary of each topic, followed by more in-depth discussion. Organizational acronyms: » JAEA: Japan Atomic Energy Agency » IAEA: International Atomic Energy Agency » NIRS: National Institute of Radiological Sciences » NRA: (Japan) Nuclear Regulatory Au- thority » METI: Ministry of Economy, Trade, and Industry » MEXT: Ministry of Education, Culture, Sports, Science and Technology » IRID: International Research Institute for Nuclear Decommissioning Acknowledgements: Many thanks to Andrew Pothecary, de- signer of many of the infographics which appear on throughout the Situation Re- port sections. Many of these previously appeared in the Number 1 Shimbun, the magazine of the Foreign Correspondents’ Club of Japan (FCCJ) and are credited as such, while others were made specifical- ly for this report. We would also like to thank the many researchers and special- ists who have given us valuable feedback on our drafts. Of course any errors are our own. Special thanks to Alvin Cheung for design and layout. Extra special thanks to Jory Felice for his fabulous cover design.
  10. 10. 10 2.1- Issues at Fukushima Daiichi Nuclear Powerplant (FDNPP) The disaster at the Fukushima Daiichi site is ongoing. Though many urgent is- sues need to be addressed, it is difficult to call it an “emergency” now. Rather, it is a long-term crisis. Conditions on- site appear to be stable, and cautious, methodological approaches have been developed and implemented for deal- ing with the many problems. Progress is very slow. The following sections sum- marize the current status of decommis- sioning, removal of spent fuel rods, wa- ter problems, and other issues, noting that the information comes almost en- tirely from TEPCO and for the most part cannot be independently confirmed. Notable changes since last year’s report: Updates on the overall decom- missioning timeline; updates on prepa- rations for removing remaining spent fuel from the spent fuel pools; progress on water treatment and remediation; discussion of the tritiated water prob- lem; update on the completion of the frozen underground wall; update on preparations for melted fuel debris re- moval; updated muon imaging results; description of progress of remote/ro- botic investigations inside the reactors; discussion of onsite worker issues. 2.1.1 — Decommissioning roadmap Briefly put, everything that is being done now and which will be done on site un- til the year 2020 is merely preparation for the really hard work of removing the hazardous highly radioactive melted fuel debris from the bottom of the re- actor buildings. TEPCO’s roadmap for this has slipped more than once, though the company seems to be basically on schedule so far, but the work gets much harder from this point forward. Much of the needed technology is either untried or does not yet exist. Regulatory over- sight is in place, but we still don’t think it has enough teeth. Incremental progress was made in 2016 and 2017 on the most challenging issues, with some important successes regarding investigations in- side the reactor vessels. TEPCO released its first decommission- ing roadmap—a timeline describing the expected schedule of work on the clean- up of the Daiichi site—in Dec. 2011, and has issued periodic updates, most re- cently in July 2017, with word of a nota- ble revision being released in Sept. 2017. The original 2011 plan is a complicated document that points to the ultimate removal of melted fuel from the reactor containments at some as yet unknown date in the future, demolition of the build- ings themselves, and remediation of the site. Much of the actual planning for later stages of the work cannot be done un- til success has been assured on earlier stages, particularly in solving the many water-related problems on the site. In fact, some of the technologies expect- ed to be required for actually extracting the melted fuel do not exist yet, though research and development is underway and some notable technical successes have been achieved.
  11. 11. D1: Site guide to the Fukushima Daiichi Nuclear Power Plant (FDNPP), July 2017 (source: TEPCO) D2: Long-term decommissioning diagram (source: TEP- CO, annotations by SAFECAST)
  12. 12. 12 TEPCO: Mid-and-long-Term Road- map towards the Decommissioning of Fukushima Daiichi Nuclear Power Station Units 1-4, Dec. 21, 2011 corp-com/release/betu11_e/imag- es/111221e14.pdf A major revision of the roadmap, which prioritizes risk reduction over speed, was published by the Cabinet Office in July, 2015. Revision of the Mid-and-Long-Term Roadmap quake/nuclear/decommissioning/pd- f/20150725_01a.pdf Progress Status and Future Challenges of the Mid-and-Long-Term Roadmap toward the Decommissioning of TEP- CO’s Fukushima Daiichi Nuclear Power Station Units 1-4 (Outline) quake/nuclear/decommissioning/index. html This NRA document from February, 2015 describes the overall strategy: Measures for Mid-term Risk Re- duction at TEPCO’s Fukushi- ma Daiichi NPS (as of July 2017) pdf TEPCO issues periodic updates about decommissioning plans and progress. These documents are compiled from many other TEPCO sources and bring the basic information together in one place. Confusingly, because government input and approval is required for these plans, the same documents are also made available by METI and the NRA. This version from July, 2017 describes the current schedule: Summary of Decommissioning and Contaminated Water Management July 27, 2017 (hereafter referred to as SCDMW) quake/nuclear/decommissioning/pd- f/20170727_e.pdf In addition, METI recently published an English-language PR pamphlet describ- ing the ongoing work and future plans: Important Stories on Decommissioning: Fukushima Daiichi Nuclear Power Sta- tion, now and in the future, 2017 quake/nuclear/decommissioning/ pdf/20170927_roadmap.pdf The overall long-term timetable is divided into three phases [Fig. D2]: » Phase 1 (2012–2013): This involved stabilization and other work done prior to the start of removing spent fuel, and was essentially completed on time. » Phase 2 (2014–2021): This is the cur- rent phase, and includes the continu- ing removal of spent fuel, and prepa- ration for removing melted fuel debris from the reactor containments, includ- ing solving many water-related issues onsite. » Unit 1: Spent fuel removal to start in FY2023 (originally sched- uled to begin in FY2017) » Unit 2: Spent fuel removal to start in FY2023 » Unit 3: Spent fuel removal to start in FY2018 (originally scheduled to begin in FY2015) » Unit 4: Spent fuel removal com- pleted in 2014
  13. 13. 13 » Phase 3 (2021 -?): This is the melt- ed fuel debris removal and decom- missioning process itself. Though the general approach was determined in mid-2017, currently the actual plan for extracting it is scheduled to be de- cided in FY2019 (pushed back from FY2018). Despite recently announced delays in spent fuel removal and of the decision regarding melted fuel debris extraction, as of Sept. 2017 the cur- rent road map maintains the previous FY2021 start date for the extraction of the debris. Many kinds of work are carried on con- currently onsite, and TEPCO can be said to have met its primary goal for the end of Phase 1 and the start of Phase 2. The more detailed timelines are frequent- ly adjusted, as are actual work targets, and often slip by months or years. The 2014–2021 phase is very long, and this reflects the fact that many technologies do not exist for what needs to be done, and are requiring years of development. The melted fuel removal and decommis- sioning phase expected to start in 2021 currently has no estimated end point, though TEPCO has previously stated it would be 30–40 years from now. Based on prior experience at Three Mile Island and at Chernobyl (where melted fuel has not yet started to be removed), we should assume it will require several decades. TEPCO does not make its plans in iso- lation, but receives guidance and in- structions from Japanese government agencies and organizations such as the METI, NRA, JAEA, NIRS, and IRID, and is required demonstrate to the IAEA that progress is being made onsite. As noted above, NRA and IAEA conduct period- ic reviews and onsite inspections, but we feel that so far they have lacked the manpower, if not the mandate, to con- duct the kind of unannounced daily in- spections that seem to be warranted. As noted above, this may be changing. The government seems to rely too heavily on what TEPCO tells it, and the IAEA seems to depend primarily on information pro- vided by the Japanese government. We’re left to conclude that the only entity which really knows what’s happening on- site is TEPCO itself, and that despite its disclosure policy it is able to be selective about what data it releases, how, and when. The IAEA issued a (preliminary) inspection report on February 17, 2015, and its major Fukushima report in August, 2015, as described above. Documents released by UN agencies invariably ad- here to a careful diplomatic language which requires a fair amount of parsing and reading between the lines. Not sur- prisingly, however, the IAEA reserved its strongest criticism for TEPCO’s failures of management and oversight. Partly be- cause of continued problems in these ar- eas, we assume, new corporate entities, the Fukushima Daiichi Decontamination and Decommissioning Engineering Com- pany and the Nuclear Damage Compen- sation and Decommissioning Facilitation Corporation, were established, intend- ed to improve oversight of these critical long-term projects. IAEA International Peer Review Mission On Mid-And-Long-Term Roadmap Towards The Decommissioning Of TEPCO’s Fukushima Daiichi Nuclear Power Station Units 1–4 (Third Mission) Preliminary Summary Report To The Government Of Japan, 9–17 February 2015 missionreport170215.pdf METI provides a number of decommis- sioning-related reports on its website: quake/nuclear/decommissioning/index. html
  14. 14. 14 Summary of Decommissioning and Contaminated Water Management July 27, 2017 (SCDMW) quake/nuclear/decommissioning/pd- f/20170727_e.pdf The FDADA site makes a lot of relevant information about the decommission- ing process easily accessible. It is not always as up to date as releases from TEPCO or METI, however: Website of the Information Portal for the Fukushima Daiichi Accident Analysis and Decommissioning Activities The IRID consortium (International Re- search Institute for Nuclear Decommis- sioning) has been developing technol- ogies, primarily robots, for use in the decommissioning process. A careful look at their web site can give an idea of the state of the technologies under consideration and development, but one gets the sense that they do not want to share too much potentially proprietary in- formation. IRID website: 2.1.2 — Overall conditions According to recent TEPCO reports, cooling water continues to be circulated inside the reactor buildings. The tem- peratures of the Reactor Pressure Vessel (RPV) and Primary Containment Vessel (PCV) of Units 1-3 were maintained with- in the range of approx. 20-35C in recent months. [Fig. D3] No significant change in the density of radioactive materials newly released from reactor buildings in the air was detected, and cold shutdown conditions have been maintained. In June 2017, the radiation exposure dose at the Daiichi site bound- ary from the release of radioactive mate- rials from the Unit 1-4 reactor buildings was determined to be less than 0.00028 mSv/year. During the same period, the density of the radioactive materials new- ly released from Units 1-4 in the air and measured at 8 monitoring posts at the Daiichi site boundary was determined to be approximately 2.2×10-12 Bq/cm3 for Cs-134, and 1.2×10-11 Bq/cm3 for Cs- 137. [Fig. D4] Summary of Decommissioning and Contaminated Water Management; July 27, 2017 (SCDMW) quake/nuclear/decommissioning/pd- f/20170727_e.pdf As noted in the UNSCEAR 2016 White Paper, which cites Steinhauser et al. 2015, although continuing radioactive releases from the Daiichi site are gener- ally low enough to require sophisticated equipment to detect them, decommis- sioning and dismantling activities onsite have occasionally led to more noticeable secondary releases even years following the accident. Specifically, radioactive dust has on occasion been released into the environment when parts of the damaged reactor buildings have been moved. The releases described have been detectable and in at least one case led to measur- able contamination, but their potential impact on health has been considered negligible (see “Tobichitta-jikken” in Sec 2.4: Food). It is more important that what happened in the cases known to date be well understood and adequate measures be implemented to prevent more serious releases from occurring. Steinhauser et al, Post-Accident Sporadic Releases of Airborne Radio- nuclides from the Fukushima Daiichi
  15. 15. D3: (top and bottom) Graphs of temperatures inside reactor units 1-3, April-July 2017 (source: TEPCO) D4: Annual radiation dose at Daiichi site boundaries from radioactive materials (cesium) released from Reactor Building Units 1-4 (source: TEPCO)
  16. 16. 16 Nuclear Power Plant Site, Environ. Sci. Technol., 2015, 49 (24), pp 14028– 14035 acs.est.5b03155 2.1.3 — Spent fuel pools TEPCO successfully removed all of the spent fuel from Unit 4 in late 2014, but over 1500 spent fuel rods remain atop the damaged reactor buildings of units 1, 2, and 3. These units are proving to be more difficult, not least because radiation levels where workers need to be are still too high for safety. The schedules for removing the remaining fuel rods has been pushed back sev- eral times as a result. Preparations for removing the spent fuel from Unit 3 are far along, and the work should com- mence within the coming year. The last fuel pools are now due to start being emptied by 2023. This fuel needs more secure long-term storage than in the common pool onsite, though no prog- ress seems to have been made on pre- paring a place to put it. One of the most critical ongoing tasks is the removal of hazardous spent fuel assemblies from the spent fuel pools of Units 1, 2, 3, and 4 (Unused fuel assem- blies also need to be removed, but are not as hazardous). The process poses unique engineering and worker protec- tion challenges, and serious mishaps could have wider negative consequences for the public and the environment. After the success of emptying Unit 4’s spent fuel pool in 2014, TEPCO seemed ready to move quickly on the others, but later decided that it was more prudent to take the extra time necessary to prepare the sites and technology more thoroughly in order to reduce worker radiation doses. This includes developing more remotely operated systems to do the actual work. Unit 1: This spent fuel pool contains 392 fuel as- semblies, and the schedule for starting the removal of the spent fuel has been pushed back from FY2017 to FY2023. As was the case with Units 3 and 4, which also suffered massive hydrogen explo- sions, the upper level of Unit 1 is a chaot- ic tangle of fallen structural elements and equipment, and mounds of radioactive rubble. Work for surveying and remov- ing this must be done remotely for safety reasons, and the risk of the release of ra- dioactive dust is significant. The building was covered for several years following the accident by a lightweight structure intended to contain ongoing releases of radiation to the air. This needed to be removed to allow the next steps of the work to proceed. Roof and wall panels of the building cover had been dismantled by mid-November 2016, and the cover’s pillars and beams were removed in May 2017. Detailed 3D scans of the condi- tions on the operating floor have been made and developed into digital models that will guide subsequent work planning. Rubble removal work has been ongoing, but slow. The reasons given for pushing the start of spent fuel removal back from 2020 to 2023 recently were the need to ensure that radioactive dust was not re- leased during the process, the challeng- es of safely removing some of the large fallen structural elements and equipment that lie over the spent fuel pool itself, and the challenges of minimizing the expo- sure of workers onsite. [Fig. D5, D6] Detailed TEPCO report on Unit 1 issues, March 2017 (in Japanese) clear/decommissioning/committee/os- ensuitaisakuteam/2017/03/3-02-03.pdf
  17. 17. D5: Unit 1 workflow for dismantling building cover (source: TEPCO) D6: Unit 1 refueling floor: Above: 3D model showing fallen ceiling crane and fuel handling machine (FHM), Right: present condition (source: TEPCO)
  18. 18. 18 Independent summary and discus- sion of this document in English: web/?p=16279 Unit 2: This spent fuel pool contains 615 fuel as- semblies, and the start of removal was recently pushed back to 2023. Because this reactor did not suffer a devastating explosion like the others, the erection of a large independent secure structure like those at units 3 and 4 will probably not be necessary. But because of the high dose rates and the need for adequate access for remotely-operated heavy machinery, as well as space needed to install the fuel handling equipment and fuel removal frame, it has been decid- ed to completely dismantle the building above the top floor. The area around Unit 2 has been cleared for heavy machinery access, which entailed dismantling small buildings nearby, beginning in Septem- ber, 2015. An enclosed workspace had been constructed atop a large platform alongside the refueling floor on the west- ern side of the building, and an opening is being made in Unit 2’s wall there to al- low access to the operating floor. Once the existing roof and upper walls have been dismantled, a new structural cov- er will be built. The decision has not yet been made whether this will cover the entire upper floor or only a portion of it. In general less information is available from TEPCO about the plans and status of Unit 2’s spent fuel removal work than for theother units. This may reflect the less challenging nature of the work there compared to the other reactor buildings, since the operating floor appears to be largely intact. Nevertheless more infor- mation should be made available to the public. [Fig . D7, D8] Unit 3: Preparations for removing the spent fuel from Unit 3 are far along. After several delays, fuel removal is currently sched- uled to begin in 2018. Although the 566 assemblies that need to be removed (514 used, 52 unused) are far fewer than there were in Unit 4, the Unit 3 operating floor level had been largely inaccessible to workers because of high dose rates until the completion of decontamination and floor shielding in late 2016. As at the other units, much of the work onsite is being done remotely for this reason. The removal of the fuel rods is expected to be done primarily remotely as well. The required equipment has been complet- ed and tested, and workers trained in its use. Like at Unit 4, a large structure is being built at Unit 3 which will house the new fuel handling machine, crane, and oth- er necessary equipment. As Unit 4, the structure is designed so that it places minimal extra load on the damaged re- actor building. The area surrounding Unit 3 was cleared so that an indepen- dent supporting structure for the new operating floor and the new cover could be built. This takes the form of a large horizontal cylinder, often referred to as a “dome” (though technically speaking it is a “cylindrical vault”). It was built in sec- tions offsite at Onahama Bay, where the assembly procedure was rehearsed, and installation at Unit 3 began in July 2017. As of Sept 2017 two of the eight sec- tions were in place. Installation of guide rails and other structure for the new fuel handling machine was completed in July 2017. Other dose-reduction mea- sures are being implemented at Unit 3 in preparation for the fuel removal work. The first floor was partly decontaminated using newly developed remote machin-
  19. 19. ery, including machines which use blast- ed dry-ice, and this work will continue as the results are evaluated. [Fig. D9, D10] TEPCO: Installation of Unit 3 spent fuel removal cover dome roof at Fukushima Daiichi Nuclear Power Station (Second unit) date/2017/201709-e/170907-01e.html TEPCO: Preparation of fuel remov- al from the spent fuel pool in Unit 3 reactor building at Fukushima Daiichi Nuclear Power Station — Demonstra- tion of fuel handling machine and crane, Jan 18, 2016 ma-np/handouts/2016/images/hand- outs_160118_01-e.pdf (This document has good diagrams and plans of most of the aspects discussed above, and includes a timeline) [D7- IMAGE] Cover proposals for Unit 2 spent fuel removal: Left: Full cover, right: Partial cover (source: TEPCO) D8: Unit 2 large external structure at refueling floor level (source: TEPCO)
  20. 20. 20 The current phase of work at Unit 3 is largely construction and installation of the required shelter and equipment, which generally appears to be proceeding ac- cording to plan, in a predictable fashion. But this required several years of chal- lenging and unpredictable cleanup and site preparation beforehand. Removal of rubble from the roof was completed in Oct. 2013. The spent fuel pool was also full of structural debris which was care- fully mapped and modeled in 3D to help guide the remotely controlled removal equipment. [Fig. D11] TEPCO, Unit 3 spent fuel pool 3d debris maps etc, Jan 2015 (in Japanese) clear/ pdf/150129/150129_01_3_5_07. pdf There were mishaps, such as equipment being accidentally dropped back into the pool while it was being removed, and highly radioactive dust was released while a large girder was being removed from the roof adjacent to the pool (known as the Tobichitta jikken. See Sec 2.4: Food). One of the most challenging tasks, the removal of the 20-ton fuel handling ma- chine, the largest piece of debris in the Unit 3 spent fuel pool, was safely con- cluded in August 2015. It required the development of special cutting and lifting apparatus. Similar apparatus will likely be necessary at Unit 1. In delicate operation, 20-ton object removed from Fukushima fuel pool, Aug 2,2015 ter/fukushima/AJ201508020026 Removal Of Unit 3 Fuel Handling Machine Hailed As Major Milestone In Decommissioning Effort com/release/2015/1256671_6844.html The removal of the remaining large piec- es of debris was completed in Novem- ber, 2015. After the large debris was removed, visual inspections inside the pool were conducted in December to determine the condition of the fuel as- semblies. Six deformed assemblies had been identified earlier, and no significant deformities in other fuel assemblies was detected in the December inspections. After this, the detailed removal plan could be devised. Main work to help remove spent fuel at Unit 3 missioning-16 Investigative results inside the Unit 3 spent fuel pool missioning-11 As much as we think TEPCO deserves criticism, we feel the engineering thinking and implementation for the spent fuel re- moval at Unit 3 deserves to be acknowl- edged. Conditions onsite make cleanup and site preparation risky, however. TEP- CO and its partners appear to be taking the lessons learned from the difficulties they encountered at Unit 3 into consider- ation as they develop their plans for Units 1 and 2. Unit 4: The removal of 1533 fuel rods from Unit 4’s spent fuel pool was successfully completed without mishap on Dec. 22, 2014. The process necessitated remov- ing a large quantity of rubble and dis- mantling unnecessary upper structure, building a very large, multistory structure which cantilevered over the damaged reactor building to stabilize it while not imposing any additional load, and in- stalling new fuel handling machinery. The removed fuel assemblies were placed in fuel transfer casks, 71 times in all, and
  21. 21. D9a: Assembly sequence for Unit 3 cover (source: TEPCO) D9b (above left): Rendering of completed Unit 3 cover (source: TEPCO) D9c (above): Sectional view showing structural relationship of Unit 3 “dome” (grey), new supporting framework (red), and existing Unit 3 (white) (source: TEP- D10: (left) Unit 3 cover sections in place, Oct. 25, 2017(updated) (source: TEPCO) D11: (left) 3D debris map of Unit 3 spent fuel pool (source: TEPCO)
  22. 22. 22 trucked a short distance to the common pool onsite at Daiichi, where it is expect- ed to be stored for 10–20 years, and then transferred to more secure storage (though the decisions about how and where remain to be made). Prior to the commencement of this operation and throughout there were very loud and alarming claims from many quarters that failure was likely and that mishaps would lead to the extinction of the human race. Because we had looked closely at the seismic stability and structural damage reports for Unit 4 beforehand, we con- sidered these claims to be exaggerated, and in fact, giving credit where it is due, we have been impressed by the engi- neering design of this particularly chal- lenging and unprecedented project. It is functioning as proof of concept for the removal of spent fuel from the remaining reactor units. [Fig. D12, D13] Tepco info page about decommission- ing, including PR videos: ion/planaction/removal-e.html 2.1.4 — Water problems The water problems we hear so much about at the Daiichi site remain serious and are an obstacle to starting other decommissioning work. They also con- tinue to pose potential consequences for the environment and marine life, and so need to be closely monitored. The influx of groundwater into the site pos- es the greatest problems, and because it has been impossible to actually map its underground flow, efforts to control it have had unpredictable consequences. These problems have forced TEPCO to think ambitiously and innovatively, and though none of the ideas have worked out quickly or perfectly, they appear to be advancing technology in some ar- eas. No-one really expected the water prob- lems at Daiichi to be solved easily. Some progress appears to be being made, however. The continuing root cause is that both the water which has been being circulated through the damaged reactors to cool the melted fuel and groundwa- ter which has been leaking through the site and into the buildings themselves both become radioactively contaminat- ed (though precisely what it is coming into contact with and where remains un- clear). TEPCO has implemented several “contaminated water countermeasures,” to deal with various facets of the overall problem with varying degrees of success. Their approach, which has remained un- changed for several years, can be divid- ed into three main components, each of which involves several technologies: D12: Fuel removal structure at Unit 4 (source: TEPCO) D13: Diagram showing relation of new structure to damaged Unit 4 (source:
  23. 23. 23 1. To effectively filter the cooling water which is being recirculated to re- move radionuclides. 2. To prevent groundwater from com- ing into contact with radioactive ma- terials. 3. To prevent contaminated water from leaking out into the environment. TEPCO claims to be making progress in all these areas, and the IAEA still reserv- edly acknowledges this. As noted above, more independent confirmation of radi- ation levels in the water onsite has be- come available. But there’s still a lot we don’t know. The overall scale of the problem may be best illustrated by the number of water tanks needed to store the radioactive water. TEPCO estimates that roughly 600 m3 of groundwater is flowing into the area surrounding Daiichi Units 1, 2, 3, and 4 per day, and that about 140 m3 of this finds its way into the reactor build- ings. As of July 2017, there were over 1,100 massive water tanks onsite for storing water in various stages of treat- ment, with more being constructed. The first tanks used were 374 hastily-con- structed bolted-flange types which had a propensity to leak. Since May 2015 these have been being dismantled and replaced with more secure welded tanks. Asahi: PHOTO: More than 1,100 water storage tanks at Fukushima plant ... and counting ter/fukushima/AJ201602130025 Dismantling of flange tanks completed in H1 east area missioning-2 Storage of Contaminated Water/Treated Water (Increase in Number of Tanks) missioning-2 Dismantling of flange tanks completed in H1 east area missioning-2 Storage of Contaminated Water/Treated Water (Increase in Number of Tanks) missioning-2 Situation of Storage and Treatment of Accumulated Water including Highly Concentrated Radioactive Materials at Fukushima Daiichi Nuclear Power Sta- tion (321st Release) Sept 25, 2017 corp-com/release/betu17_e/imag- es/170925e0101.pdf A fairly good peer-reviewed paper de- scribing the groundwater contamination situation onsite was published in 2016 (paywalled). It includes a good descrip- tion of the underlying geology and how this affects the water flow: The aftermath of the Fukushima nuclear accident: Measures to contain ground- water contamination; Gallardoa and Maruib, Science of The Total Environ- ment, Volume 547, 15 March 2016, Pages 261–268 article/pii/S0048969715312845 Other recent papers have estimated the amount of radionuclides being released into the ocean due to the continued leak- age of contaminated groundwater, in context with the extremely large releases from Daiichi in March-April of 2011, as well as compared to other accidents and events. We will touch on this in Sec 2.2: Environment.
  24. 24. 24 2.1.4.a — Radionuclide re- moval systems TEPCO has spliced together several different systems for removing radionu- clides from water onsite. These started as an unreliable hack, but have gradu- ally grown and become more reliable, and a modular approach has made it possible to scale up and add new ca- pabilities. While breakdowns and poor performance were frequently noted in earlier years, the technology seems to be one of the few major elements of the overall water strategy that is working well now. The inability of these systems to remove tritium, however, together with the lack of space to build more storage tanks, means that a difficult political decision will need to be made soon about releasing it into the ocean. TEPCO continues to use several water treatment systems—ALPS, SARRY, and Kurion—to remove radionuclides from the recirculating water. First, contami- nated water from the reactor buildings is processed by two adsorption systems, SARRY (Simplified Active water Retrieval and RecoverY system) and Kurion (the name of the manufacturer), to reduce the levels of cesium and strontium. Then it is desalinated. After this, some of the water is recirculated to cool the reactors, and the rest sent to the Multi-nuclide Remov- al Facility. This system, the largest water processing system onsite, is designed to remove 62 nuclides, and includes three subsystems which are variants of ALPS (Advanced Liquid Processing System). The processed water is sent to storage tanks. All of these systems have been steadily upgraded, and TEPCO claims that with the exception of tritium, radio- nuclides in the finally processed water are below or near the detection limit. In January 2015, TEPCO reported that the multi-nuclide removal system has been processing approximately 1,260 tons of water per day, while the other systems have been processing approximately 800 tons per day. This has enabled TEPCO to treat previously stored water as well as newly recirculated water. In May 2017, TEPCO announced that it had complet- ed the purification treatment, including strontium removal, of the highly con- taminated water in the storage tanks. Water which is pumped into the reactor buildings for cooling eventually finds its way to the basements of the reactors and connected buildings, where it mixes with groundwater inflow, and is eventual- ly pumped out to be recirculated again. TEPCO counts this basement water as storage, and the level is kept fairly con- stant. It is currently at approximately 50,000 tons in total. [Fig. D14, D15] TEPCO: Update on the com- pletion of contaminated wa- ter treatment, January 23, 2015 ma-np/handouts/2015/images/hand- outs_150123_02-e.pdf TEPCO: target nuclides to be removed [does not include target levels!] ion/planaction/images/150517.pdf Situation of Storage and Treatment of Accumulated Water including Highly Concentrated Radioactive Materials at Fukushima Daiichi Nuclear Power Sta- tion (321st Release) Sept 25, 2017 corp-com/release/betu17_e/imag- es/170925e0101.pdf TEPCO Contaminated Water Treatment Info page: (includes system diagrams, maps of what is stored where, and how water storage has changed over time) ion/planaction/alps/index-e.html
  25. 25. D14 (above): Water treatment flow diagram (source: TEPCO) D15 (left) Graph of hanges in stored water quantities, July 2016- July 2017 (source: TEPCO)
  26. 26. 26 Information Portal for the Fukushima Daiichi Accident Analysis and Decom- missioning Activities: Progress Report: Contaminated water countermeasures missioning-16#p4 The nuclide removal process generates highly contaminated waste products, primarily sludge from the adsorption sys- tems, as well as waste fluid. These are transferred to high-integrity containers (HIC) and stored onsite. As of February 2017, there were approximately 3,519 of these containers being stored. FDADA: Management status of second- ary waste from water treatment missioning2/progress2/decommission- ing-16-en/ 2.1.4b Tritiated Water Prob- lems The treated water, however, still con- tains tritium (H3) at well above allowable levels. This has led to a host of tech- nical and political problems. Tritium is considered by the expert community to pose a fairly low health risk compared to radionuclides like strontium or cesium. Its allowable levels for drinking water or discharge into the environment are ap- proximately ten-thousand times higher than for Cs-134, for instance — 60,000 Bq/L for Tritium vs 60Bq/L for Cs-134. But it is wrong to conclude that it pos- es no risk whatsoever, and no credible scientist would make that claim. On the contrary, a number of expert “dissent- ers” from the consensus viewpoint say that the risks from tritium exposure may be well underestimated. TEPCO has spent years building trust with the local fishermen’s cooperative “JF Zengyoren,” and by including them in planning and acceding to their conditions for third-party water testing and other as- surances, has gained their agreement regarding the release of water pumped from less-contaminated “bypass” and “subdrain” wells. Discussions regarding what to do about the tritiated water have been continuing for years, and TEPCO seemed optimistic that some agreement could eventually be reached despite con- tinued opposition from the fishermen. Both the IAEA and the NRA have repeat- edly recommended that TEPCO conduct a controlled release of the tritiated water, saying that if it were done carefully there would be minimal impact to the environ- ment. TEPCO has repeatedly resisted the idea, however, being unwilling to do so without the clear agreement from the local fishermen. Then suddenly, in July of 2017, Tokyo Electric Power Co. Holdings new chairman Takashi Kawamura said at a press conference that the decision to release the tritiated water to the ocean had already been made. A predictably loud public outcry ensued, and even TEPCO staff were caught unprepared. In the days following, TEPCO issued statements which backtracked from Kawamura’s, but the damage to TEP- CO’s agreements with the cooperatives and to the reputation of the fisheries had been done. They are now back to square one. In addition, much of the global pub- lic assumes this water is already being dumped. Japan Times: Fukushima fishermen fight release of tainted water as tritium stand- off continues, March 19, 2017 news/2017/03/19/national/fukushi- ma-fishermen-fight-release-tainted-wa- ter-tritium-standoff-continues/
  27. 27. 27 Japan Times: Fukushima’s tritiated wa- ter to be dumped into sea, Tepco chief says, July 14, 2017 news/2017/07/14/national/ science-health/tepco-says-de- cision-already-made-release-ra- dioactive-low-toxic-tritium-sea-fisher- men-irate/#.WdCPHjOB3GI Newsweek: Fukushima’s Nuclear Waste Will Be Dumped Into The Ocean, Japa- nese Plant Owner Says 7/14/17 ma-nuclear-waste-dumped-ocean-japa- nese-protests-637108 WSJ : Fukushima Watch: Regulator Calls on Tepco to Discharge Tritium Water, Jan 21, 2015 time/2015/01/21/fukushima-watch-reg- ulator-calls-on-tepco-to-discharge-tri- tium-water/ The actual concentrations of tritium in the water stored onsite at Daiichi are assumed to vary from between approx 0.5 to 4.2 million Bq/L. This means that it would need to be diluted between 8 and 75-fold in order to reach the legally allowed concentration of 60,000 Bq/L. Diluting it would not reduce the total ra- dioactivity released, however. In the case of less-contaminated water pumped up from the Daiichi site and released with the agreement of local fishermen, TEP- CO allowed third-party testers to con- firm that any tritium was below TEPCO’s own operational target of 1500 Bq/L. If it were to commit to the same opera- tional target for the tritiated water, then perhaps agreement is not out of reach. In 2013, TEPCO formed a Tritiated Water Taskforce comprised of specialists from government and academia, civil society representatives, and industry (including TEPCO itself). This taskforce evaluated 11 options for dealing with the tritiated water, looking at five treatment methods combined with different pre-treatments. The options it evaluated included: geo- logical injection, discharge into the ocean, atmospheric emission as vapor, atmospheric emission as hydrogen gas, and underground storage. For reasons of time, safety, and cost, ocean discharge was considered the least objectionable option. The group estimated that off- shore release would take 4-6 years. Tritiated water taskforce report June 2016 quake/nuclear/decommissioning/pd- f/20160915_01a.pdf Isotopic separation was examined by the task force as a potential pre-treatment for release to the ocean or atmosphere. This technology got a fair amount of atten- tion in the press in 2015-2016, and the Kurion company received a large devel- opment contract in 2015. The company said at the time that it had demonstrated the effectiveness of its system, and could begin processing tritium-contaminated water at Daiichi as soon as mid-2017. Such a system would be extremely ex- pensive, however. Kurion Building a Prototype Modular Detritiation System Sept 8, 2015 totype-modular-detritiation-system/ Kurion Modular Detritiation System loads/2014/11/MDS-Brochure-for-WEB. pdf Bloomberg: How Kurion Plans to Clean Up Fukushima’s Tritium Nuclear Waste, Feb 6, 2016 articles/2016-02-04/how-kurion-plans-
  28. 28. 28 to-clean-up-fukushima-s-tritium-nuclear- waste 2.1.4.c — Groundwater prob- lems Unless the flow of groundwater into the reactor building basements is con- trolled, it won’t be possible to carry out the next steps to prepare for removing the melted fuel debris. The solution im- plemented so far is an ambitious series of underground dams made of frozen soil, and dozens of pumps. All of the work is complicated by the radioactivity of the water and the site itself. The fro- zen wall has been activated, and TEP- CO believes that it is effective in partial- ly reducing the water inflow. According to most sources, before any measures were put in place, approx- imately 300 m3 of groundwater was entering the reactor buildings per day. Since implementing countermeasures, TEPCO believes this has been reduced to 140 m3/day. The problem is rooted in the initial siting of the building. Though the ground level where the building sits was originally much higher, major ex- cavation was done to lower the site in order to make the pumping of cooling water from the ocean easier, bringing the buildings into contact with the permeable geological layers through which ground- water flows. Under normal conditions the buildings had an adequate seal against this water, as well as efficient “subdrain” pumps to remove it, but since the 2011 disaster large amounts of water have been entering the reactors, apparently through cracks or other openings under- ground. Exactly how and where remains a mystery. Several methods of dealing with this water are being tried with mixed success so far. [Fig. D16] TEPCO: Current Status of groundwater inflow countermeasures (in Japanese), Aug 30 2017 ma-np/handouts/2017/images2/hand- outs_170830_03-j.pdf Sealing the buildings Sealing any below ground-level openings in the reactor buildings would seem to be the best and most direct option for keeping groundwater out, and efforts are being made to identify where the leaks are and to develop sealing methods. But the radiation levels inside and next to the reactor buildings are generally too high to allow humans to work safely for any length of time. In fact, radiation in many parts of the buildings is high enough to give lethal exposures within a short time (over 5000 mSv/hr in Unit 1, 4400 mSv/ hr or over in Units 2 and 3, with a high- ly publicized spot reading of 9.4 Sv/hr in Unit 2). Techniques for repairing cracks and other gaps remotely are being inves- tigated, and are expected to be required in order to prepare the structures for the removal of melted fuel after 2021, but they do not currently exist. No significant progress has been reported on these ef- forts since last year. [Fig. D17] Groundwater Bypass Because the groundwater is flowing into the site from the mountains on the side opposite the ocean, it has been hoped that intercepting as much of this water as possible before it reaches the site could greatly reduce the amount reaching the reactor buildings. Groundwater on the uphill mountain side so far has not shown high levels of radioactive contamination, so after an agreement was reached with Japan Fisheries Cooperatives to have it stored and independently tested before being released to the ocean—the first agreement of this sort reached—the pumping and diversion of the water was
  29. 29. 29 begun in April 2014. As of July 25, 2017, 296,991 m3 of groundwater has been pumped up and released. The IAEA es- timated that this has reduced ground- water ingress by approximately 25%, not as much as was hoped, but an im- provement nonetheless. The bypass wa- ter is tested by third parties once every ten days. TEPCO’s operational targets for radionuclides in this water are 1 Bq/L for Cs134 and Cs137, 3 Bq/L for gross beta, and 1500 Bq/L for H3 (tritium). All of these are far below Japanese limits as well as WHO drinking water standards. Recent results show that levels much lower than TEPCO’s targets have been achieved. Detailed analysis results regarding the water quality of the groundwater being pumped out for by-passing at Fukushi- ma Daiichi Nuclear Power Station, September 1, 2017 quake/nuclear/decommissioning/pd- f/20170901_01a.pdf Bypass water sampling at southern outlet, Sept 9, 2017 (Japanese) ma-np/f1/smp/2017/images3/pump_ well_17090902-j.pdf Subdrains A system of about 40 drain pumps, called “subdrains,” located near the reactor and turbine buildings, existed prior to the ac- cident. These were intended to mitigate potential problems from groundwater during normal operation of the plant, but were seriously damaged and have been unusable since March 2011. This system has been repaired. Tests were conduct- ed in 2014, and since September 2015, about 360 m3 per day of water has been pumped up and processed. After being purified and stored in tanks, like the water from the groundwater bypass, it is sub- ject to third-party monitoring conditions and the approval of the Japan Fisheries Cooperatives before it is released to the ocean. A total of 371,383 m3 has been released as of July 25, 2017. Since the full-scale operation of the frozen earth wall commenced, TEPCO believes that in combination with subdrain operation it is able to adequately control the ground- water levels around the reactor buildings. TEPCO: Groundwater pump-up by Subdrain or Groundwater drain ion/planaction/sub-drain/index-e.html D16: Schematic sectional view of the Daiichi site showing relationship of groundwater levels, under- ground ice wall (“land-side impermeable wall”), pumps, etc. (source: TEPCO)
  30. 30. 30 Subdrain water test results, (Japanese) Sept 23, 2017 ma-np/f1/smp/2017/images3/subsur- face_170923-j.pdf English guide: ma-np/f1/smp/2016/images/weight- ed_average_form-e.pdf Detailed analysis results regarding the water quality of the groundwater pumped up by sub-drain and purified at Fukushima Daiichi Nuclear Power Station, Sept. 1, 2017 quake/nuclear/decommissioning/pd- f/20170901_01b.pdf TEPCO releases first batch of decon- taminated Fukushima groundwater to sea, September 14, 2015 ter/fukushima/AJ201509140069 In addition to the 41 subdrains near the reactor buildings, five additional ground- water drains were dug near the sea side impermeable wall (see below). Filtering and releasing this water was begun in November 2015. However, the water proved to be too highly contaminated with tritium to meet the discharge criteria, and in January 2016 TEPCO announced that it would be stored instead. The high tritium levels maybe due to contact with highly contaminated soil near the sea- wall. Closure of the seawall also raised groundwater levels behind it significantly, requiring more water to be pumped than planned. Fukushima Daiichi NPS Prompt Report (Jan 08,2016) Recent Topics:Tepco Stores Rather Than Discharges From Groundwater Drain After Monitoring Detects Higher Contamination Levels com/release/2016/1265513_7763.html D17 (right): Plan showing lo- cations of high doserates in Unit 3, 1Fl, as of Feb. 2015. Areas indicted in red are over 50 mSv/hr. (source: TEPCO)
  31. 31. 31 Asahi Shimbun: TEPCO confronts new problem of radioactive water at Fukushi- ma plant, Dec 26, 2015 ter/fukushima/AJ201512260045 Since the closing of the frozen earth wall, the quantity of water pumped up via the subdrains has been strongly affected by rainfall. TEPCO says that the treatment capacity for the subdrain water is being incrementally increased to accommo- date the growing volume of pumped-up groundwater during the high rainfall sea- son. UNSCEAR 2016 notes the connec- tion between periods of increased rainfall and sporadic increases of Cs137 levels in the ocean near Daiichi: “The general decrease of the direct re- leases to the ocean has been confirmed by the continuous monitoring at the out- lets of FDNPS. However, this monitor- ing has also shown sporadic increases of 137Cs levels as a result of exchanges of water between the harbour and the ocean. Most of these sporadic increas- es correspond to heavy rainfall events. Hirose has concluded that there are two main pathways by which radionuclides are continuing to be discharged into the ocean. One is a continuous release due to exchange of waters between the har- bour and the open ocean, and the other is a sporadic discharge of contaminated water via drainage because of rainfall.” Developments Since The 2013 UN- SCEAR Report On The Levels And Ef- fects Of Radiation Exposure Due To The Nuclear Accident Following The Great East-Japan Earthquake And Tsunami, p9 publications/Fukushima_WP2016.html Frozen underground wall After examining several alternatives, TEPCO decided upon a controversial plan to construct a 30 meter-deep wall, or dam, of frozen earth around the reac- tor buildings in hopes that this will pro- vide an effective barrier to water ingress. The structure, called the “land-side im- permeable wall,” forms a rectangle ap- proximately 500m by 200m, with a total perimeter of about 1500m. Though the frozen earth technique is well-proven and is often used in very challenging mining and tunneling operations, the wall at Daii- chi is the longest ever actually attempted, and is being done with an ever-present radiation hazard as well as many under- ground obstacles. Onsite tests began in August 2013, construction began in June 2014, and freezing tests were begun in April 2015. Construction of the system was completed in October, 2015. Freez- ing was started on the sea side and part of the mountain side from March 2016, and on 95% of the mountain side from June 2016. The wall is currently about 99% frozen. [Fig. D18] TEPCO Website: Land-side Imperme- able Wall (Frozen Soil Wall) sion/planaction/landwardwall/index-e. html Land-side impermeable walls missioning-15 TEPCO : Recent Topics: Fukushima- Installation Of Facilities Required For ‘Ice Wall’ Construction Is Complete,Feb 09,2016 sion/planaction/landwardwall/index-e. html
  32. 32. 32 General description of the frozen wall system with diagrams. TEPCO: Information on frozen wall test- ing, May 21, 2015: ma-np/handouts/2015/images/hand- outs_150521_01-e.pdf TEPCO’s data indicates that the frozen wall has greatly reduced the water inflow, but much about the plan remains unpre- dictable. There are many interconnected and constantly fluctuating variables. In order to prevent more contaminated wa- ter from leaking out of the reactor build- ings and finding its way to the ocean, it is necessary to keep the water level in the basements of the reactor buildings be- low the level of the groundwater in the surrounding areas. For this reason, the groundwater level must be decreased gradually and carefully monitored and controlled. TEPCO seems to think it will be possible to contain any leakage within the perimeter of the frozen wall, and has been pumping water in and out to main- tain the proper levels. The closure of the seaside impermeable wall in September 2015 led to unpredictable fluctuations of groundwater levels there, and similar unpredictability may occur with the fro- zen wall. Partly for this reason, the Japan NRA called for caution and a long testing period to confirm the effects, and initial- ly only gave approval for the portion on the ocean-side of the reactors, as well as several “control” segments on the mountain-side, to be fully frozen. Obtain- ing NRA approval at each stage, TEPCO was able to freeze almost all of the re- mainder by August 2017. Together, the delays put the frozen wall about a year behind schedule. [Fig. D19] TEPCO evaluates the effectiveness of the frozen earth wall by measuring the difference of the groundwater level on the inside of the wall compared with the outside on both the mountainside and seaside (through direct measurement at wells), the amount of groundwater flow- ing into the reactor buildings (by direct measurement of the amount they pump in and out compared to the levels they measure inside), and the amount of in- flowing groundwater from the mountain side (estimated by totaling the measured pumping amounts and subtracting rain- fall). They consider the sharp decrease in the amount of water that needs to be pumped out from the wells between the reactor buildings and the seawall to be a major indicator of the effectiveness of the frozen wall. The Aug 30, 2017 TEPCO document linked below (in Japanese) details their findings [Fig. D20]: » F: Groundwater inflow from the moun- tain side (estimate): March 2016 : 760 m3/day > July 2017 600 m3/day (F is estimated by totaling the mea- sured pumping amounts and sub- tracting rainfall) » A: Volume pumped from subdrains (measured): March 2016 : 390 m3/day > July 2017 500 m3/day » B: Building inflow (estimated from actual measurements): March 2016 : 170 m3/day > July 2017 140 m3/day » C: Groundwater amount pumped to “4m deck” between reactor buildings and seawall (estimated from actual measurements): March 2016 : 250 m3/day > July 2017 120 m3/day (Even after rains they’re pumping less here) » D: Amount leaking from beyond the frozen wall, i.e. deep underground: March 2016 : 0 m3/day > July 2017
  33. 33. D18: Schematic showing the placement of the underground ice walls. (source: TEPCO) D19: Diagram illustrating how un- derground water levels will need to be careful controlled to prevent the outflow of highly contaminated water from the damaged buildings int the surrounding ground (Source: Asahi Shimbun) D20: Diagram showing analysis of the effectivness of the frozen wall based on com- plex water flow (see text for explanation) (source: TEPCO)
  34. 34. 34 0 m3/day (assumed) » E1: Rainfall recharge (estimated from actual measurements): March 2016 : 20 m3/day > July 2017 150 m3/day » E2: Groundwater level fluctuation (generally negative): March 2016 : -30 m3/day > July 2017 -10 m3/day TEPCO: Current Status of groundwater inflow countermeasures (in Japanese), Aug 30 2017 ma-np/handouts/2017/images2/hand- outs_170830_03-j.pdf This 2016 TEPCO report explained the frozen underground wall plan in detail: TEPCO: Study results of the land-side impervious wall, Feb 15, 2016 ma-np/handouts/2016/images1/hand- outs_160215_02-j.pdf Also available at: pdf TEPCO: Progress of Landside Imper- meable Wall freezing: the Second Stage Feb 9, 2017 ma-np/handouts/2017/images/hand- outs_170209_02-e.pdf TEPCO: Phase 3 freezing of Landside Impermeable Wall starts at Fukushima Daiichi Nuclear Power Station, Aug 22, 2017 ma-np/handouts/2017/images/hand- outs_170822_01-e.pdf User “Sotan” posted a detailed English summary of this document on the Phys- ics Forums online discussion: threads/japan-earthquake-nucle- ar-plants-part-2.711577/page- 41#post-5378915 Sankei Shimbun: Japan NRC calls for reconsideration of seaside frozen wall (Japanese), Jan. 22, 2016 news/150322/afr1503220003-n1.html Asahi Shimbun: NRA to allow part of frozen soil wall at Fukushima plant, Feb. 15, 2016 ter/fukushima/AJ201602150062 Asahi Shimbun: NRA calls a halt to TEP- CO’s plan to freeze soil at Fukushima plant, Feb 10, 2016 ter/fukushima/AJ201602100079 Asahi Shimbun: TEPCO nears ‘deep freeze’ of soil wall at Fukushima plant, Feb. 21, 2016 ter/fukushima/AJ201602210030 Sea-side impermeable wall Groundwater samples taken from ob- servation wells in the area between the reactor buildings and the ocean front (in- take and port areas) have in the past reg- ularly shown high levels of radionuclides, particularly gross beta (which includes strontium) but also cesium. In Oct. 2014, samples from one set of wells showed over 7.8 million Bq/L gross beta, which declined to 500,000 Bq/L by Jan. 2015. Tests from March 2016 showed gross beta of up to 600,000 Bq/L, Cs-137 up to 36,000 Bq/L, and tritium up to 63,000 Bq/L. Although the total radiation levels are many thousands of times lower than they were in March and April, 2011, this degree of contaminated water has con- tinued to seep into the ocean, contam-
  35. 35. 35 inating and recontaminating the seabed offshore (see Part 2.3: Environment and Decontamination). To stop this seepage, TEPCO constructed a 30m deep wall of sheet pilings called the “sea-side imper- meable wall” along the ocean frontage of the site, about 780m in total length. It was completed in Oct. 2015. [Fig. D21] Impermeable seaside wall closure — Sept 2015 ma-np/handouts/2015/images/hand- outs_150909_01-e.pdf ma-np/handouts/2015/images/hand- outs_150910_01-e.pdf As noted above, closing this wall caused groundwater levels behind it to rise. The increased pressure caused deflection in the wall and a gap to open between it and the ground. The wall was reinforced, repairs being completed in early Decem- ber 2015. missioning-16 Based on testing of seawater outside of the wall, the seaside impermeable wall seems to have been effective in reduc- ing the amount of contaminated water reaching the ocean. Testing data from mid-December 2015 showed the levels of strontium and gross beta there had dropped to close to the detection limit when the wall was fully closed in October 2015, and stayed low through mid-De- cember that year. On Sept 29, 2017, TEPCO’s port water test results showed that Cs-137 was de- tected at low concentrations (0.49- 1.2 Bq/L) at 7 of the 8 sample points, and was undetected at the other. Tritium, maximum levels of 3.7 Bq/L, was detect- ed at 4 of the 8 points, and gross beta was detected at 4 sample points, maxi- mum levels of 18 Bq/L. Cs-134 was un- detected. Water in the inner port (intake channel) was moderately higher, with Cs 137 detected at all 4 sample points, with a maximum of 6.8 Bq/L ; tritium at all 4 sample points up to 21 Bq/L, and gross beta at 2 sample points, with up to 28 Bq/L. All of these indicate that the sea- side impermeable wall is fairly effective: D21: Schematic plan and section showing the placement of the sea-side impermeable wall, underground layers, and the ocean. (source: TEPCO)
  36. 36. 36 TEPCO: 2. Analysis Results of Seawater Obtained around Fukushima Daiichi NPS (Inside of the Port of Fukushi- ma Daiichi NPS), Sept 29, 2017 ma-np/f1/smp/2017/images/intake_ca- nal_map-e.pdf TEPCO: Analysis Results of Seawater Obtained around Fukushima Daiichi NPS September 29, 2017 (Inside of Unit 1-4 Water Intake Channel), Sept 29, 2017 ma-np/f1/smp/2017/images/2tb-east_ map-e.pdf Fukushima Daiichi wall seems effective as seawater pollution drops: TEPCO 6 November 2015 news.html?id=590 A graph on the summary progress report from Feb. 09 2016 showed con- tinued low levels of Sr90, beta, etc thru 12/12/2015 corp-com/release/betu16_e/imag- es/160209e0101.pdf TEPCO regularly releases test data for water taken from the port area as well as from offshore (see Section 2.3.3—The Ocean), but we feel that not all relevant locations are covered, and reiterate that without independent confirmation some skepticism remains about the accuracy of the figures TEPCO provides. TEPCO: Monitoring by sampling- Re- sults of Radioactive Analysis around Fukushima Daiichi Nuclear Power Station, index page to measurements onsite and immediately offshore: ma-np/f1/smp/index-e.html Trenches Each of the reactor turbine buildings is connected to seawater intake pumps and other equipment at the waterfront by interconnected underground tun- nels called trenches, for seawater piping and power cables primarily, as well as a number of connecting shafts and smaller underground structures. The trenches of Units 2 and 3 in particular became filled with several thousand tons of highly con- taminated water during the early phase of the disaster, and due to continuing leaks and poorly-understood flow mech- anisms, appeared to contain a mixture of contaminated cooling water and ground- water. As we reported in previous years, several early attempts to remove it by us- ing freezing and other techniques failed, but significant progress was made in late 2014 and afterward. Water in the seawa- ter piping trench of Unit 1 is relatively low in contamination, so no removal opera- tions are planned. Sealing and filling the trenches at Unit 2 was completed on July 10, 2015. Contaminated water transfer from Unit 3 was completed on July 30, and the trench shaft filled and sealed by August 27. Work at Unit 4 was done in two stages, and completed on Dec. 21, 2015. TEPCO says that closing these routes for contaminated water leakage at Unit 3, for instance, has reduced the total radioactivity of the water accumu- lated in the trenches and turbine build- ings to 1/10 of its previous level, and has significantly decreased the risk of highly contaminated water reaching the ocean. There have been no significant devel- opments regarding the trenches since then. [Fig. D22] TEPCO: Seawater Piping Trench (as of July 30, 2015) ion/planaction/trench/index-e.html
  37. 37. Removal of contaminated water and filling of Unit 4 seawater pipe trench complete commissioning-11 2.1.5 — Melted fuel removal The process of removing the melted fuel debris from inside the reactors will require decades, and the most optimistic scenarios have it starting in 2021. The last time something simi- lar was attempted was over 25 years ago, at Three Mile Island, where melt- ed core removal was completed in 1990 (it has not yet been attempted at Chernobyl). Consequently there are not many people with relevant experi- ence to call on for assistance. A new, well-funded research institute has been established to incubate the kinds of technologies that will be necessary. Meanwhile many systematic attempts at surveying conditions inside the re- actor pressure vessels remotely have been made, with increasing success. Removing melted fuel debris from in- side the damaged reactors and storing it safely is the primary goal of the de- commissioning process. As mentioned above, this is not scheduled to actually start until around 2021, and everything that has been done onsite until now and which will be done until the actual re- moval process begins is preparation for that stage. Because of the tremendous technical challenges involved, which ex- ceed the experience and know-how of any existing single company, the Inter- national Research Institute for Nuclear Decommissioning (IRID) was estab- lished in 2013. This consortium is un- der the guidance of the Japan Atomic Energy Agency and the National Insti- tute of Advanced Industrial Science and Technology, and includes as founding members major corporations such as Toshiba, Hitachi-GE Nuclear Energy, Ltd., and Mitsubishi Heavy Industries, Ltd., as well as major electric utilities from around the nation. IRID’s primary mission is to research and develop the necessary technologies for decommis- D22: Plan of underground trenches at Units 2 and 3 (source: TEPCO)
  38. 38. 38 sioning the nuclear reactors, which it seeks to do in cooperation with compa- nies and organizations both inside and outside of Japan. IRID has been very ac- tive, seeking and funding proposals and organizing meetings and workshops, some of which have had tangible results, particularly in robotics. [Fig. D23] Two primary scenarios for extracting the melted fuel debris have been under con- sideration. The so-called “submersion” or “flooding” method was considered the current front-running idea until recently. This method, derived in part from that used at Three Mile Island, would involve plugging leaks in the reactor contain- ment so it can be filled with water, and then using remote-controlled machinery inserted from above on long telescoping arms to cut up and extract the melted fuel in pieces. The water would provide good radiation shielding and therefore a good margin of safety for workers. But after a series of insufficiently promising experiments to develop methods to plug cracks and openings in the reactors to prevent the radioactive water from leak- ing, it was judged too difficult. In August 2017 the Nuclear Damage Compensa- tion and Decommissioning Facilitation Corporation (NDF) announced that the “dry” or “side entry” method had been selected for further development and implementation instead. [Fig. D24, D25, D26] Mainichi: New proposal suggests removing Fukushima plant’s melted nu- clear fuel from side, Aug 1, 2017: cles/20170801/p2a/00m/0na/014000c This presentation from April. 2015 gives an overall explanation of IRID’s plans that have been under consideration: R&D activities related to the fuel debris retrieval from the Fukushima Daiichi NPS, April 9, 2015 Also: cn235p/Session5/S5-4-Takashi-Satoh. pdf The following video from May 2014 ex- plains the submersion method (uses Flash): IRID: Explanatory video for Submersion Method for Fuel Debris Retrieval, May 2014 Under the “dry removal” scenario, a long robotic arm would be inserted into the re- actor vessels from the side, and the de- bris would be shaved off gradually with drills and/or lasers. Though the method is called “dry,” all indication is that the melted debris would remain covered with water (“partial submersion”), but the re- moval process itself would require mov- ing the radioactive material through the open air, while water is poured remotely to suppress radioactive dust. This detailed 2016 report from NDF de- scribes the removal scenarios and the results of planning and testing in great detail: NDF: Technical Strategic Plan 2016 for Decommissioning of the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company Holdings, Inc., July 13, 2016 gic-plan/book/20170322_SP2016eFT. pdf The 2017 NDF Technical Strategic Plan (Japanese only available so far) was re-
  39. 39. 39 leased on August 31, 2017, after the de- cision to use the side entry method was announced: 東京電力ホールディングス(株)福島第一 原子力発電所の 廃炉のための技術戦略 プラン 2017 gic-plan/book/20170831_SP2017FT.pdf Before this can be done, the melted fuel debris must be located, the reactor buildings decontaminated and shielded so that workers can enter, power and communications re-established inside the buildings, and methods developed to minimize the further spread of con- tamination during the decommissioning process. Progress has been made in all of these areas. Meanwhile, though some initial progress has been made, most of the robotic equipment necessary to sur- vey inside the torus rooms and lower levels of the containment buildings is still being developed and tested. This is nec- essary both to identify places that need repair to stop leaks, and also to precisely locate the melted fuel itself. The sobering reality is that the technology for dealing with many of the tasks that melted fuel removal will entail does not yet exist. In March, 2015, Naohiro Masuda, the former manager of the Fukushima Daini NPP, who successfully prevented a melt- down there in March 2011, and who is now TEPCO’s manager in charge of de- commissioning Daiichi, gave a very can- did interview to NHK television. In it he spoke frankly about the challenges and uncertainties surrounding the decom- missioning effort, highlighting many of the same issues discussed in the 2015 version of this report. He said, in part: “We have no idea about the debris, we don’t know its shape or strength. We have to remove it remotely from 30 meters above. But we don’t have that kind of technology yet. It simply doesn’t exist….It’s a very big chal- lenge. Honestly speaking, I cannot say it’s possible but I also do not wish to say it’s impossible.” Although anyone who had been follow- ing the plans and developments closely D23: Initially proposed debris extraction methods (source: NDF)
  40. 40. D24: Proposed robot arm for use in side entry debris extraction (source: NDF) D25: Sequence of insertion of robot arm, site preparation, and debris extraction (source: NDF) D26: Removal and transfer of debris to storage in side entry method (source: NDF)
  41. 41. 41 at that point should not have been sur- prised to hear this, these statements were a shock to much of the wider public, who felt they had been lulled into thinking the process was already technically more fully developed and under control. NHK: Nuclear Watch: Decommissioning Chief Opens up, March 31, 2015 news/nuclearwatch/20150331.html In Feb. 2016, NRA commissioner Toyoshi Fuketa stressed that plans for dealing with the fuel debris were still being for- mulated, and removing all of it may take too much time — 70 or 80 years — and so might not ultimately prove to be the best course of action. Other options, like “removing as much fuel debris as pos- sible and solidifying the rest,” should be considered, he said. We have heard no real follow up on this idea, as IRID, NDF, and others have announced plans that seem to assume complete removal, but the statement highlights the unsettled state of planning for this important step. Japan Times: NRA commissioner suggests plan to remove all fuel debris at Fukushima plant may not be best option, Feb. 20, 2016 news/2016/02/20/national/nra-commis- sioner-suggests-plan-remove-fuel-de- bris-fukushima-plant-may-not-best-op- tion/#.Vs6dHJN96gQ Much of the work being done at the Daii- chi site that relates directly to removing the melted fuel debris involves surveys of various kinds to locate the fuel itself and ascertain the conditions inside the reac- tor containments. Since 2015 advanced imaging techniques using muons and remotely-controlled explorations inside the reactor vessels have been used with increasing success. This presentation shows the estimated distribution of fuel debris in Unit 1, 2, and 3 based on many sources of information: TEPCO/IRID/IAE: Estimation of current status inside RPV and PCV at Fukushi- ma daiichi NPS [aka ECS], July 3, 2017 mi_en.pdf 2.1.5a MUON IMAGING Muons are subatomic particles that are created when cosmic rays pass through the Earth’s upper atmosphere. Muon to- mography is a method which measures the number and trajectory of muons after they have passed through objects. Be- cause nuclear materials are denser than other metals and concrete, their location can be identified using this technology, much like an X-Ray. After meeting with considerable success in tests, muon tomography has been used for locat- ing melted fuel inside the reactors. The detectors are left in place for months to gradually build up an increasingly detailed image. A team led by the High Energy Accelerator Research Organization (KEK) has to date produced informative imag- es from Unit 1 in 2015, Unit 2 in 2016, and Unit 3 in 2017. A team from Nagoya Univ. using a different implementation of the technology obtained useful images of Unit 2 in 2014. In all cases, the re- searchers concluded that little or no fuel remained in its original locations. Difficul- ty in placing the detectors so that good images of the bottom of the reactor pres- sure vessels (RPVs) could be obtained leaves uncertainty about how much melted fuel, if any, remains inside them. The conditions in each of the three reac- tors is different, but in each case careful estimates indicate that some of the fuel remains at the bottom of the RPV, and the rest fell through to the concrete base- pad below. [Fig. D27, D28, D29]
  42. 42. D28 (left): Muon scan image of the interior of Unit 1 pressure vessel, March 2015. (source: TEPCO) D27 (top): Diagram showing placement of muon scan detector plates to be used at Unit 2. (source: TEPCO/IRID) D29: Muon scan images of Unit 2 by Nagoya Univ. in 2014 (source: Nagoya Univ.)