The water temperature in the containment vessels and the spent fuel pools (SFPs) varies mostly around less than 32o<\/sup>C and no great changes have been seen. The state of releases of Xenon-135 (half-life roughly nine hours), released when uranium fuel undergoes fission is also unchanged and it can therefore be estimated that the state of the reactors is stable. Further, according to an assessment by TEPCO in June 2020, around 14,000 becquerels per hour (Bq\/h) of radioactive materials were being released from the buildings (Fig.1).<\/p>\n Fig. 1. Releases of Radioactivity from Units 1 to 4 of Fukushima Daiichi Nuclear Power Station (Bq\/h)<\/p>\n \u00a0<\/strong><\/p>\n At the same time, decay heat has fallen greatly with the passage of time, and thus the volume of cooling water injected into the reactors has been reduced (falling from 7-10m3<\/sup> per hour in May 2011 to 1.4-1.5 m3<\/sup> per hour in July 2020).\u00a0<\/p>\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 Table 1: State of Spent Fuel Pool Cleanup\u00a0 <\/strong><\/p>\n Work to dismantle the upper section of the Units 1 and 2 exhaust stack, in which a fracture was discovered in a supporting pillar, began on August 1, 2019 and was completed on May 1, 2020.\u00a0The 120m exhaust stack was dismantled by dividing it into 23 blocks. This work, originally scheduled for completion during FY2019, was delayed by equipment troubles and adverse weather conditions. In addition, the Units 1 and 2 exhaust stack has had a lid placed on it, but as the water level in the exhaust stack drain sump pit is fluctuating, the location of the influx is under investigation.<\/p>\n Changes in the number of workers per day are shown in Fig. 2.\u00a0As of June 2020, the number was 4,020, roughly half what it was at the peak of 7,450 as of March 2015. At the same time, since problems originating in work mistakes are becoming more frequent at the site, in October 2019 TEPCO carried out an organizational restructuring that included the reassignment of 120 employees who had been working at TEPCO\u2019s head office to Fukushima Daiichi Nuclear Power Station. However, the assignment of employees to the site was not actually increased. The changes in the number of cases of work non-conformance are shown in Fig.3, as reported on the TEPCO website, but there has been no change in the trend and there is concern that a manpower shortage still exists at the site.<\/p>\n Fig. 2: Change in Average Number of Workers (Actual Values) Per Day on Weekdays<\/p>\n![\"\"](\"https:\/\/cnic.jp\/english\/wordpress\/wp-content\/uploads\/2020\/10\/f1_release.jpg\")
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