Progress report

I. Confirmation of the reactor conditions

1. Temperatures inside the reactors

Through continuous reactor cooling by water injection, the temperatures of the Reactor Pressure Vessel (RPV) bottom and the Primary Containment Vessel (PCV) gas phase have been maintained within the range of approx. 15 to 25°C for the past month, though they vary depending on the unit and location of the thermometer.

2. Release of radioactive materials from the Reactor Buildings

As of January 2017, the density of radioactive materials newly released from Reactor Building Units 1-4 in the air and measured at the site boundary was evaluated at approx. 3.5×10^-12 Bq/cm³ for Cs-134 and 1.1×10^-11 Bq/cm³ for Cs-137 at the site boundary. The radiation exposure dose due to the release of radioactive materials was less than 0.00029 mSv/year at the boundary.

Note: Different formulas and coefficients were used to evaluate the radiation dose in the facility operation plan and monthly report. The evaluation methods were integrated in September 2012. As the fuel removal from the spent fuel pool (SFP) commenced for Unit 4, the radiation exposure dose from Unit 4 was added to the items subject to evaluation since November 2013. The evaluation has been changed to a method considering the values of continuous dust monitors since FY2015, with data to be evaluated monthly and announced the following month.

3. Other indices

There was no significant change in indices, including the pressure in the PCV and the PCV radioactivity density (Xe-135) for monitoring criticality, nor was any abnormality in the cold shutdown condition or criticality sign detected.

Based on the above, it was confirmed that the comprehensive cold shutdown condition had been maintained and the reactors remained in a stabilized condition.

II. Progress status by each plan

1. Contaminated water countermeasures

To tackle the increase in accumulated water due to groundwater inflow, fundamental measures to prevent such inflow into the Reactor Buildings will be implemented, while improving the decontamination capability of water treatment and preparing facilities to control the contaminated water

Operation of groundwater bypass

• From April 9, 2014, the operation of 12 groundwater bypass pumping wells commenced sequentially to pump up groundwater. The release started from May 21, 2014 in the presence of officials from the Intergovernmental Liaison Office for the Decommissioning and Contaminated Water Issue of the Cabinet Office. Up until February 21, 2017, 258,866 m³ of groundwater had been released. The pumped-up groundwater was temporarily stored in tanks and released after TEPCO and a third-party organization had confirmed that its quality met operational targets.
• Pumps are inspected and cleaned as necessary based on their operational status.

Water treatment facility special for Subdrain& Groundwater drain

• To reduce the groundwater flowing into the buildings, work began to pump up groundwater from wells (subdrains) around the buildings on September 3, 2015. The pumped-up groundwater was then purified at dedicated facilities and released from September 14, 2015. Up until February 21, 2017, a total of 276,441 m³ had been drained after TEPCO and a third-party organization had confirmed that the quality of this purified groundwater met operational targets.
• Due to the level of the groundwater drain pond rising since the closure of the sea-side impermeable walls, pumping started on November 5, 2015. Up until February 21, 2017, a total of approx. 119,000 m³ had been pumped up. Approx. 30 m³/day is being transferred from the groundwater drain to the Turbine Buildings (average for the period January 19 - February 15, 2017).
• The effect of ground water inflow control by subdrains is evaluated by both correlations:the "subdrain water levels” and the “difference between water levels in subdrains and buildings” for the time being.
• However, given insufficient data on the effect of rainfall after the subdrains went into operation, the method used to evaluate the inflow into buildings will be reviewed as necessary based on data to be accumulated.
• Inflow into buildings tended to decline to below 200 m³/day when the subdrain water level decreased to below T.P. 3.5 m or when the difference in the water levels with buildings decreased to below 2 m after the subdrains went into operation.
• As a measure to enhance subdrains and groundwater drains, shared pipes from subdrain pits to the No. 2 relay tank were divided into independent pipes for each pit and operation started from February 10. In addition, to reduce the volume of groundwater drain transferred to the Turbine Buildings, pretreatment equipment was installed and went into operation from January 30. To improve the treatment capability of subdrains and groundwater drains, work is underway to duplicate the system for the pretreatment equipment (its implementation plan was approved on February 10). An area is being constructed to install additional water collection tanks and temporary water storage tanks.

Figure1: Evaluation of inflow into buildings after the subdrains went into operation

Construction status of land-side impermeable walls

• As for the land-side impermeable walls (on the mountain side), freezing and closure of seven unfrozen sections have been advanced with a phased approach. Regarding two of the seven sections, as a result of freezing started on December 3 and a supplementary method implemented (completed on February 8), the temperature declined below 0°C in the area to which the supplementary method was applied. In the next phase, freezing of four of the remaining five sections will start. Prior to the freezing, a supplementary method has been implemented from February 22.
• The effect of the land-side impermeable walls (on the mountain side) will be evaluated in terms of groundwater level, inflow volume into the buildings, groundwater volume pumped from subdrains and groundwater volume transferred to the area 4 m above sea level.
• The effect of the land-side impermeable walls (on the sea side) will continue to be evaluated.

Figure2: Closure of part of the land-side impermeable walls(on the mountain side)

*1:Water amount with which water-level gauge indicates 0% or more
*2:Since September 10, 2015, the data collection method has been changed (Evaluation based on increased in storage: in buildings and tanks → Evaluation based on increase/decrease in storage in buildings)
 “Inflow of groundwater/rainwater into buildings” = “Increase/decrease of water held in buildings”
 +“Transfer from buildings to tanks” - “Transfer into buildings (water injection into reactors and transfer from well points, etc.)”
*3:Since April 23, 2015, the data collection method has been changed. (Increase in storage (1)+(2) → (1)+(2)+*)
*4:On February 4, 2016 and January 19, 2017, corrected by reviewing the water amount of remaining concentrated salt water
*5:“Increase/decrease of water held in buildings” used to evaluate “Inflow of groundwater/rainwater into buildings” and “Storage increase” is calculated based on the data from the water-level gauge.
 During the following evaluation periods, when the gauge was calibrated, these two values were evaluated lower than anticipated. (March 10-17, 2016: Main Process Building; March 17-24, 2016:
 High-Temperature Incinerator Building (HTI); September 22-29, 2016: Unit 3 Turbine Building)
*6:For rainfall, data of Namie (from data published by the Japan Meteorological Agency) is used. However, due to missing values, data of Tomioka (from data published by the Japan Meteorological Agency)
 is used alternatively (April 14-21, 2016)

Figure3: Status of accumulated water storage

Operation of multi-nuclide removal equipment

• Regarding the multi-nuclide removal equipment (existing, additional and high-performance), hot tests using radioactive water have been underway (for existing equipment, System A: from March 30, 2013, System B: from June 13, 2013, System C: from September 27, 2013; for additional equipment, System A: from September 17, 2014, System B: from September 27, 2014, System C: from October 9, 2014; for high-performance equipment, from October 18, 2014).
• As of February 16, the volumes treated by existing, additional and high-performance multi-nuclide removal equipment were approx. 331,000, 321,000 and 103,000 m³ respectively (including approx. 9,500 m³ stored in the J1(D) tank, which contained water with a high density of radioactive materials at the System B outlet of existing multi-nuclide removal equipment).
• To reduce the risks of strontium-treated water, treatment using existing,additional and high-performance multi-nuclide removal equipment has been underway (existing: from December 4, 2015; additional: from May 27, 2015; high-performance: from April 15, 2015). Up until February 16, approx. 304,000 m³had been treated.

Toward reducing the risk of contaminated water stored in tanks

• Treatment measures comprising the removal of strontium by cesium absorption apparatus (KURION) (from January 6, 2015) and secondary cesium absorption apparatus (SARRY) (from December 26, 2014) have been underway. Up until February 16, approx. 348,000 m³ had been treated.

Measures in Tank Areas

• Rainwater, under the release standard and having accumulated inside the fences in the contaminated water tank area, was sprinkled on site after eliminating radioactive materials using rainwater-treatment equipment since May 21, 2014 (as of February 20, 2017, a total of 75,171 m³).

Closure of Unit 2 seawater pipe trench vertical shaft C

• Regarding the Unit 2 seawater pipe trench, contaminated water in the trench was removed by June 30 and filling was completed on July 10, 2015. As vertical shaft C has remained and been monitored as an observation well without closing the top, the water-level increase in the shaft was considered attributable to groundwater inflow. Monitoring of the shaft was terminated and the shaft will be closed in March.

Progress of accumulated water treatment in the Unit 1 T/B

• Accumulated water of the Unit 1 Turbine Building (T/B) will be treated down to the lowest floor surface by the end of FY2016 as part of efforts to reduce the risk of accumulated water leakage from buildings.
• Following the completion of work to reduce the dose and remove obstacles, installation of transfer equipment is underway. Inspection and test operation will start sequentially from the end of February. Furthermore, as a measure to reduce dust, sludge, which may float in the air as dust, was collected from February 1 before the floor surface was exposed.

2. Fuel removal from the spent fuel pools

Work to help remove spent fuel from the pool is progressing steadily while ensuring seismic capacity and safety. The removal of spent fuel from the Unit 4 pool commenced on November 18, 2013 and was completed on December 22, 2014

Main work to help remove spent fuel at Unit 1

• The status of rubble under the fallen roof is being investigated (from September 13, 2016 and schaduled for completion at the end of February, 2017) to collect data, which will then be used when considering rubble removal methods for the Unit 1 Reactor Building operating floor. No significant variation associated with the work was identified at monitoring posts and dust monitors. The building cover is being dismantled, with anti-scattering measures steadily implemented and safety first.
• An annual inspection of cranes used in the work to dismantle the Unit 1 building cover is underway (from November 23, 2016 and scheduled for completion at the end of February, 2017).
• Pillars and beams of the building cover will be modified and windbreak sheets installed on the beams from March 2017. The pillars and beams (covered by windbreak sheets) will be restored in the 1^st half of FY2017.

Main work to help remove spent fuel at Unit 2

• To help remove the spent fuel from the pool of the Unit 2 Reactor Building, construction has been underway from September 28, 2016 on the west side of the Reactor Building to install a gantry and a front chamber accessing the operating floor. Installation of the gantry was completed on February 21. Preparatory work for installation of the front chamber is underway (the installation will be completed in late April 2017).

Main work to help remove spent fuel at Unit 3

• From January 17, work started to install the cover for fuel removal, etc. (stoppers^*1: hanging was completed on February 13; FHM girder^*2: work will start from early March).
  _{*1 Projections to horizontally support the fuel removal cover to the reactor building.
   *2 Horizontal materials composing the gate structure. A rail will be mounted on the girder where the fuel handling machine (FHM) and cranes will travel.}

3. Removal of fuel debris

Promoting the development of technology and collection of data required to prepare fuel debris removal, such as investigations and repair of PCV's leakage parts as well as decontamination and shielding to improve PCV accessibility.

Dose reduction on the Unit 1-3 Reactor Building 1^st floors

• On the Unit 1 Reactor Building 1st floor, dose-reduction measures have been implemented. The average airborne radiation has been reduced to approx. 2 mSv/h in the northwest and west areas (approx. 50% compared to before the measures started). In the south side area, the high-dose AC pipes and DHC facilities account for the majority of the total dose. Methods are being examined to eliminate the dose source inside the AC pipes and remove residual contaminated water inside the DHC facilities.
• On the Unit 2 Reactor Building 1^st floor, a high dose rate was confirmed at ducts in the middle and elevated parts. Dose-reduction measures were implemented and the average dose in the area declined to approx. 5 mSv/h.
• On the Unit 3 Reactor Building 1^st floor, dose-reduction measures were implemented and the average dose declined to approx. 9 mSv/h in the northwest and west areas and approx. 7 mSv/h in the southeast area (approx. 50% reduction compared to before measures started). Though the airborne radiation in the southwest area has been reduced by approx. 40%, the average remains high at approx. 19 mSv/h. Removal of the dose source continues, such as small rubble in narrow parts on the floor.

Status toward investigation inside the Unit 1 PCV

• To investigate the status of fuel debris inside the primary containment vessel (PCV) (the basement floor outside the pedestal), a self-propelled investigation device will be injected into the Unit 1 PCV in March.
• A camera and dosimeter will be suspended from the 1^st floor grating outside the pedestal to inspect the status of the basement floor outside the pedestal and the opening.

Status toward an investigation inside the Unit 2 PCV

• To investigate the status inside the PCV pedestal including the fall of fuel debris, prior investigation inside the PCV was conducted on January 26 and 30, deposit on the access route of the self-propelled investigation device was removed on February 9 and the inside of the PCV was investigated using the device on February 16.
• The results of this series of investigations confirmed fallen and deformed gratings and a quantity of deposit inside the pedestal.

4. Plans to store, process and dispose of solid waste and decommission of reactor facilities

Promoting efforts to reduce and store waste generated appropriately and R&D to facilitate adequate and safe storage, processing and disposal of radioactive waste

Management status of rubble and trimmed trees

• As of the end of January 2017, the total storage volume of concrete and metal rubble was approx. 200,400 m³ (+1,900 m³ compared to at the end of December, with an area-occupation rate of 72%). The total storage volume of trimmed trees was approx. 79,300 m³ (-3,600 m³, with an area-occupation rate of 75%). The total storage volume of used protective clothing was approx. 64,700 m³ (-2,300 m³, with an area-occupation rate of 91%). The increase in rubble was mainly attributable to facing. The decrease in trimmed trees was mainly attributable to transfer to temporary storage areas. The decrease in used protective clothing was mainly attributable to the incineration of used clothing.

Management status of secondary waste from water treatment

• As of February 16, 2017, the total storage volume of waste sludge was 597 m³ (area-occupation rate: 85%) and that of concentrated waste fluid was 9,262 m³ (area-occupation rate: 86%). The total number of stored spent vessels, High-Integrity Containers (HICs) for multi-nuclide removal equipment, etc. was 3,519 (area-occupation rate: 56%).

5. Reactor cooling

The cold shutdown condition will be maintained by cooling the reactor by water injection and measures to complement the status monitoring will continue

Reduction of volume of water injected into the Unit 1-3 reactors

• The volume of water injected into the Unit 3 reactor was reduced from 4.5 to 4.0 m³/h from February 8, from 4.0 to 3.5 m³/h from February 15 and 3.5 to 3.0 m³/h from February 22. No abnormality attributable to the reduction was detected in the cold shutdown condition.
• The volume of water injected into Unit 2 reactor will be reduced in March 2017.
• Prior to the reduction of Unit 3 reactor water injection volume, real-time disclosure of plant parameters such as RPV bottom temperature started from February 7.


Figure4: Change in temperatures in the Unit 3 reactor after reducing the water injection

6. Reduction in radiation dose and mitigation of contamination

Effective dose-reduction at site boundaries and purification of port water to mitigate the impact of radiation on the external environment

Status of groundwater and seawater on the east side of Turbine Building Units 1 to 4

• Regarding radioactive materials in the groundwater near the bank on the north side of the Unit 1 intake, though the tritium density at groundwater Observation Hole No. 0-1 has been gradually increasing since October 2016, it currently stands at around 10,000 Bq/L. Though the tritium density at groundwater Observation Hole No. 0-3-2 had been gradually increasing since January 2016, it has remained constant since mid-October 2016 and stands at around 40,000 Bq/L.
• Regarding the groundwater near the bank between the Unit 1 and 2 intakes, though the density of gross β radioactive materials at groundwater Observation Hole No. 1-6 had been declining since July 2016, it has remained constant since mid-October 2016 and currently stands at around 250,000 Bq/L. Though the density of gross β radioactive materials at groundwater Observation Hole No. 1-16 had been increasing after declining to 6,000 Bq/L since August 2016, it has been declining since mid-October 2016 and currently stands at around 60,000 Bq/L. Though the tritium density at groundwater Observation Hole No. 1-17 had been declining from 40,000 Bq/L and increasing since March 2016, it has been declining since mid-November 2016 and currently stands at the same level as before the decrease at around 1000 Bq/L. Since August 15, 2013, pumping of groundwater continued (at the well point between the Unit 1 and 2 intakes: August 15, 2013 . October 13, 2015 and from October 24; at the repaired well: October 14 - 23, 2015).
• Regarding radioactive materials in the groundwater near the bank between the Unit 2 and 3 intakes, though the tritium density at groundwater Observation Hole No. 2-3 had remained constant at around 4,000 Bq/L and been declining since November 2016, it has remained constant at around 500 Bq/L. Though the density of gross β radioactive materials at groundwater Observation Hole No. 2-5 had increased to 500,000 Bq/L since November 2015 and been declining since January 2016, it has been increasing since mid-October 2016 and currently stands at around 60,000 Bq/L. Since December 18, 2013, pumping of groundwater continued (at the well point between the Unit 2 and 3 intakes: December 18, 2013 - October 13, 2015; at the repaired well: from October 14, 2015).
• Regarding radioactive materials in the groundwater near the bank between the Unit 3 and 4 intakes, though the densities of tritium and gross β radioactive materials at groundwater Observation Hole No. 3-2 had been increasing since September 2016, they have been gradually declining since the end of October from 3,000Bq/L for tritium and 3,500Bq/L for gross β radioactive materials and both are currently slightly higher than before the increase at around 1,500Bq/L. At groundwater Observation Hole No. 3-3, though the tritium density had been increasing since September 2016, it has been gradually declining from 2,500 Bq/L since early November and is currently slightly higher than before the increase at around 1,500 Bq/L. At groundwater Observation Hole No. 3-4, though the tritium density had been declining since September 2016, it has been gradually increasing from 2,500 Bq/L since the end of October and currently stands at the same level before the decline at around 4,000 Bq/L. Since April 1, 2015, pumping of groundwater continued (at the well point between the Unit 3 and 4 intakes: April 1 . September 16, 2015; at the repaired well: from September 17, 2015).
• Regarding the radioactive materials in seawater in the Unit 1-4 intake area, densities have remained low except for the increase in cesium 137 and gross β radioactive materials during heavy rain. They have been declining following the completed installation and the connection of steel pipe sheet piles for the sea-side impermeable walls.
• Regarding the radioactive materials in seawater in the area within the port, the densities have remained low except for the increase in cesium 137 during heavy rain. They have been declining following the completed installation and the connection of steel pipe sheet piles for the sea-side impermeable walls.
• Regarding the radioactive materials in seawater in the area outside the port, densities have remained constant and within the same range as before.
• The location of the sampling point “Near south release outlet” was shifted from approx. 330 to 280 m south of the south release outlet due to repair of the breakwater (from January 27). The location of the sampling point “North side of east breakwater” was shifted approx. 50 m south of the previous point (from February 11).

<Unit 1 intake north side, between Unit 1 and 2 intakes>

<Between Unit 2 and 3 intakes, between Unit 3 and 4 intakes>
Figure5: Groundwater density on the Turbine Building east side

Figure6: Seawater density around the port

7. Outlook of the number of staff required and efforts to improve the labor environment and conditions

Securing appropriate staff long-term while thoroughly implementing workers' exposure dose control. Improving the work environment and labor conditions continuously based on an understanding of workers' on-site needs

Staff management

• The monthly average total of people registered for at least one day per month to work on site during the past quarter from October to December 2016 was approx. 12,500 (TEPCO and partner company workers), which exceeded the monthly average number of actual workers (approx. 9,700). Accordingly, sufficient people are registered to work on site.
• It was confirmed with the prime contractors that the estimated manpower necessary for the work in March 2017 (approx. 5,950 per day: TEPCO and partner company workers)* would be secured at present. The average numbers of workers per day for each month (actual values) were maintained, with approx. 4,500 to 7,500 since FY2014 (see Figure 7).
   *Some works for which contractual procedures have yet to be completed were excluded from the estimate for March 2017.
• The number of workers from both within and outside Fukushima Prefecture has increased. The local employment ratio (TEPCO and partner company workers) as of January has remained at around 55%.
• The monthly average exposure dose of workers remained at approx. 1 mSv/month during FY2013, FY2014 and FY2015. (Reference: Annual average exposure dose 20 mSv/year ≒ 1.7 mSv/month)
• For most workers, the exposure dose was sufficiently within the limit and allowed them to continue engaging in radiation work.

Figure7: Changes in the average number of workers per weekday for each month since FY2014

Figure8: Changes in monthly individual worker exposure dose
(monthly average exposure dose since March 2011)

Measures to prevent infection and expansion of influenza and norovirus

• Since November, measures for influenza and norovirus have been implemented, including free influenza vaccinations (subsidized by TEPCO Holdings) in the Fukushima Daiichi Nuclear Power Station (from October 26 to December 2) and medical clinics around the site (from November 1 to January 31, 2017) for partner company workers. As of January 31, a total of 8,206 workers had been vaccinated. In addition, a comprehensive range of other measures is also being implemented, including daily actions to prevent infection and expansion (measuring body temperature, health checks and monitoring infection status) and response after detecting possible infections (control of swift entry/exit and mandatory wearing of masks in working spaces).

Status of influenza and norovirus cases

• Until the seventh week of 2017 (February 13-19, 2017), there were 362 influenza infections and 15 norovirus infections. The totals for the same period for the previous season showed 128 cases of influenza and ten norovirus infections.

Operation start of the partner company building

• As work to modify the new Administration Building into the partner company building was almost completed, partner companies are sequentially transferring to the building from February 20 to start operation.
• This measure creates an environment where staff members of TEPCO and partner companies are working together in neighboring locations to be involved in decommissioning as an integrated organization of the power station.

8. Status of Unit 5 and 6

Water level increase at mega float No. 5VOID (north side)

• On February 16, a periodical patrol of the mega float moored within the port detected an increase of ballast water level^* at one (No. 5VOID on the north side) of nine sections, by approx. 45 cm compared to the value of the previous measurement (on January 19, 2017) to sea level. _{* Water stored in ship bottom tanks, etc. to stabilize the hull}
• To investigate the seawater inflow into No. 5VOID, ballast water inside this section was transferred to the neighboring section No. 4VOID on February 17.
• On February 21, an investigation, conducted using an underwater camera into the status inside the section where an increase of ballast water level was detected, identified a detorted reinforcing plate in the lower part on the northwest side of the mega float. The investigation also identified a potential crack of approx. 10 cm (estimated) near the connection between the wall and floor. Repair methods will be considered.
• Monitoring of radioactivity density in seawater around the mega float was enhanced and confirmed no significant change in temperature.