The water temperature in the containment vessels and the\nspent fuel pools (SFPs) varies mostly around less than 30o<\/sup>C and no\ngreat changes have been seen. The state of releases of Xenon-135 (half-life\nroughly nine hours), released when uranium fuel undergoes fission is also\nunchanged and it can therefore be estimated that the state of the reactors is\nstable. Further, according to an assessment by TEPCO in July 2019, around\n29,000 bequerels per hour (Bq\/h) of radioactive materials were being released\nfrom the buildings (Fig.1).<\/p>\n\n\n\n At the same time, decay heat has fallen greatly with\nthe passage of time, and thus the volume of cooling water injected into the\nreactors has been reduced. Since the cooling water becomes contaminated through\ncontact with molten debris, etc. inside the reactors, the reduction in the\ninjected volumes of cooling water leads to a reduction in the accumulation of\ncontaminated water. In April and May of this year, a lowering and a temporary\ncessation of the injected volumes of cooling water was conducted experimentally\nin Unit 2. This suspension of injection experiment is also due to be conducted\nin Units 1 and 3 in the near future. <\/p>\n\n\n\n The state of removal of nuclear fuel from the SFPs is summarized in Table 1. Nuclear fuel removal from Unit 4 has been completed. While multiple problems have been experienced with the equipment (fuel handling equipment crane and fuel-handling machine) for removal of spent fuel from Unit 3, removal began on April 15, 2019. (It was originally set to begin around mid-FY2018.)<\/p>\n\n\n\n Work to dismantle the upper section of the Units 1 and\n2 exhaust stack, in which a fracture was discovered in a supporting pillar,\nbegan on August 1. The plan is to dismantle the 60m exhaust stack by dividing\nit into 23 blocks. Currently, dismantling work is ongoing on the uppermost\npart, but the work has been delayed by equipment troubles and adverse weather\nconditions. Creation of a landfill using the megafloat used to store\ncontaminated water in 2011-12 (a move from in front of Units 5 and 6 to in\nfront of Units 3 and 4 completed on May 16, scheduled for landfill completion\nin FY2021) as well as other tasks are now underway.<\/p>\n\n\n\n Changes in the number of\nworkers per day are shown in Fig. 2. As of July 2019, the number was 3,630,\nroughly half what it was at the peak of 7,450 as of March 2015. At the same\ntime, while the work environment is said to have improved, it is still severe. While\nthere were five heat stroke victims up to the end of September FY2017 and seven\nin FY2018, there were seven up to the end of August FY2019. <\/p>\n\n\n\n State of Contaminated Water<\/strong><\/p>\n\n\n\n Contaminated water countermeasures at Fukushima Daiichi Nuclear Power Station (FDNPS) can be broadly divided into three areas: 1) Reduction of groundwater flowing into buildings, 2) Reduction of contaminated water flowing into the sea, and 3) Reduction of the toxicity of contaminated water. Regarding the reduction of water volumes flowing into buildings, the main countermeasures are, from higher elevations downward, A) Pumping up groundwater at the groundwater bypass and releasing it into the sea (491,225m3<\/sup> up to August 27), B) Installation of a frozen earth barrier (on-land water barrier, total length roughly 1,500m) surrounding FDNPS Units 1-4. (Ground temperature has now reached below 0o<\/sup>C except for one section.) C) Pumping up water at the subdrains and releasing it into the sea (746,091m3<\/sup> up to August 27, 2019), and D) Paving of the site with asphalt to suppress permeation of rainwater into the soil. Regarding reduction of contaminated water flowing into the sea, the countermeasures being taken include A) Groundwater leakage prevention by a steel water barrier on the sea side, B) Pumping up of groundwater dammed up behind the sea-side water barrier from the well points and groundwater drains. (roughly 210,003m3<\/sup> up to August 27; as this groundwater is highly contaminated, it is being transferred to the turbine building), and other measures. Changes in generated volumes of contaminated water are as shown in Fig. 3.)<\/p>\n\n\n\n Regarding the reduction of the toxicity of\ncontaminated water, after removal of cesium and strontium and removal of\nimpurities using reverse osmosis (RO), radionuclides except for tritium are\nremoved by the multi-radionuclide removal equipment (ALPS – Advanced Liquid Processing System) and then stored in\ntanks (containing 1,054,927m3<\/sup> as of August 22. However, due to\nequipment malfunctions and other problems, in many cases radionuclides other\nthan tritium are present, only around 20% of the stored water being below the\nnotification concentration). Besides this, water remaining in buildings is\nroughly 31,810m3<\/sup>, strontium-treated water, etc. is 88,570m3<\/sup>,\nwater treated by RO is 9,831m3<\/sup>, concentrated brine is 500m3<\/sup>,\nconcentrated wastewater is 9,303m3<\/sup>, etc. <\/p>\n\n\n\n Furthermore, the Subcommittee on the Handling of Water\nProcessed by ALPS, etc. met for the first time in eight months on August 9. As\na result of large numbers of opposing views against release of water processed\nby ALPS into the ocean at a public hearing held by the subcommittee in August\n2018, the subcommittee has this time decided to also consider long-term storage\noptions.<\/p>\n","protected":false},"excerpt":{"rendered":" By Matsukubo Hajime, CNIC State of the Plant The water temperature in the containment vessels and the spent fuel pools (SFPs) varies mostly around less than 30oC and no great changes have been seen....<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[16,24],"tags":[],"class_list":["post-4677","post","type-post","status-publish","format-standard","hentry","category-accident","category-fukushima"],"acf":[],"_links":{"self":[{"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=\/wp\/v2\/posts\/4677","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4677"}],"version-history":[{"count":4,"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=\/wp\/v2\/posts\/4677\/revisions"}],"predecessor-version":[{"id":4701,"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=\/wp\/v2\/posts\/4677\/revisions\/4701"}],"wp:attachment":[{"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4677"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4677"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cnic.jp\/english\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4677"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/cnic.jp\/english\/wordpress\/wp-content\/uploads\/2019\/12\/f1_release-1024x417.jpg\")
![\"\"](\"https:\/\/cnic.jp\/english\/wordpress\/wp-content\/uploads\/2019\/12\/Table-1-Matsukubo.png\")
<\/figure>\n\n\n\n![\"\"](\"https:\/\/cnic.jp\/english\/wordpress\/wp-content\/uploads\/2019\/12\/Fig-2-Matsukubo.png\")
Fig. 2: Change in Average Number of Workers (Actual Values) Per Day on Weekdays <\/figcaption><\/figure>\n\n\n\n![\"\"](\"https:\/\/cnic.jp\/english\/wordpress\/wp-content\/uploads\/2019\/12\/Fig.-3-1024x464.png\")