At the Fukushima Daiichi Nuclear Power Station, investigations of dose distribution, contamination condition, accumulated water etc. were performed for improvement of working environment, selection of construction method etc. toward the stabilization and decommissioning of Units 1-4. Since the dose rate in the reactor building is high, various robots are utilized in the investigation. The followings are examples of exposure dose during the work. (Data source: TEPCO press release)

Date	Unit	Contents of work	Actual dose	Planned dose	Number of worker
'12.01.17	2	PCV penetration part （X-53 penetration, 1FL, R/B）drill and drop the block	Maximum exposure dose: 3.03mSv	-	54
'12.01.19	2	X-53 penetration: (1)Remove the end plate and attach the flange for the guide pipe (2)Insert a borescope and check inside	Maximum exposure dose: 3.07mSv	-	28
'12.03.14	2,3	Preliminary survey in Torus Room (Dose rate distribution)	Max. 2.87 mSv Min.0.67mSv	10mSv	6
'12.03.15, 16,21,22	2	Site investigation for installing alternative thermometer (Reactor building)	Maximum exposure dose: 3.47mSv	7mSv	-
'12.03.26	2	Investigation inside of PCV (Water level and Ambient temperature of accumulated water)	Maximum exposure dose: 5.29mSv	10mSv	34
'12.03.27	2	Investigation inside of PCV (Dose measurement)	Maximum exposure dose: 1.69mSv	-	35
'12.07.11	3	Torus Room investigation (Acquire photos and moving images, Dose rate measurement): (Engaged in robot operation, preparation, carrying the robot inside)	Maximum exposure dose: 0.58mSv	2mSv	5
'12.07.11	3	Torus Room investigation (Acquire photos and moving images, Dose rate measurement): (Engaged in Carrying the robot through the triangle corner, opening doors)	Maximum exposure dose: 5.32mSv	8mSv	6
'12.10.09	1	Investigation of the inside of PCV: Videotape the inside of PCV using a pan-tilt Pan-tilt camera (Above the grating on the first floor)	Maximum exposure dose: 2.74mSv	10mSv	53
'12.10.10	1	Investigation of the inside of PCV: Measure the accumulated water level and the atmosphere dose	Maximum exposure dose: 2.13mSv	10mSv	51
'12.10.11	1	Investigation of the inside of PCV: Videotape the inside of PCV using a CCD camera (Below the grating on the first floor)	Maximum exposure dose: 1.83mSv	10mSv	49
'12.10.12	1	Investigation of the inside of PCV: Collect samples of accumulated water	Maximum exposure dose: 1.72mSv	10mSv	48
'12.10.13	1	Investigation of the inside of PCV: Install the permanent monitoring instrument (Ambient temperature, accumulated water temperature/level)	Maximum exposure dose: 2.33mSv	10mSv	50
'12.10.24	1	Reinvestigation of operation floor (Investigation using the balloon: Current conditions of the roof debris, Radiation dose etc.)	Maximum exposure dose: 3.81mSv	5mSv	29
'12.12.11	2	Investigation on the Lower Part of Vent Pipe (Check the existence of water leakage etc.)	Maximum exposure dose: 1.75mSv	3mSv	-
'13.02.20	1	Investigation of Torus Room (Day 1) (Temperature, Dose, Camera)	Maximum exposure dose: 1.78mSv	-	20
'13.02.22	1	Investigation of Torus Room (Day 2) (Sampling of accumulated water and sediments)	Maximum exposure dose: 1.46mSv	-	20
'13.02.21	2	Investigation of R/B operation floor utilizing a gamma camera	Maximum exposure dose: 0.75ｍSv	4mSv	20
'13.03.05	2	Investigation of the Lower Part of Vent Pipe (East-southeast Vent Pipe, South-southeast Vent Pipe: Investigation of water leakage)	Maximum exposure dose: 1.07mSv	3mSv	-
'13.03.06	2	Investigation of the Lower Part of Vent Pipe (East-northeast Vent Pipe: Investigation of water leakage)	Maximum exposure dose: 0.71mSv	3mSv	-
'13.03.13	2	Investigation of the Lower Part of Vent Pipe (South-southwest Vent Pipe, West-southwest Vent Pipe: Investigation of water leakage)	Maximum exposure dose: 1.08mSv	3mSv	-
'13.03.14	2	Investigation of the Lower Part of Vent Pipe (West-northwest Vent Pipe, North-northwest Vent Pipe: Investigation of water leakage)	Maximum exposure dose: 1.57mSv	3mSv	-
'13.03.15	2	Investigation of the Lower Part of Vent Pipe (North-northwest Vent Pipe: Investigation of water leakage)	Maximum exposure dose: 1.18mSv	3mSv	-
'13.03.19	2	Investigation of the Inside of PCV (CRD replacement rail and the area near the pedestal opening: Appearance, Ambient dose and temperature)	Maximum exposure dose: 1.95mSv	3mSv	-
'13.03.24	2	Hole Drilling for the Investigation of Torus Room (Drilled a φ300mm hole on the floor)	Maximum exposure dose: 1.65mSv	3mSv	about 30 (planned)
'13.03.25	2	Hole Drilling for the Investigation of Torus Room (Drilled a φ200mm (penetrating) hole on the floor)	Maximum exposure dose: 2.04mSv	3mSv	about 30 (planned)
'13.04.09	1	Investigation of the Personnel Access Lock Room on the 1st Floor of Reactor Building (Visual inspection, Dose rate, Temperature and humidity)	Maximum exposure dose: 0.72mSv (Robots: 57mSv(FRIGO-MA), 210mSv (Packbot))	7mSv	4 (at the site)
'13.04.11	2	Investigation of Torus Room (Temperature, Dose, Image acquisition)	Maximum exposure dose: 1.65mSv	-	-
'13.04.12	2	Investigation of Torus Room (Accumulated water sampling, Sediments sampling)	Maximum exposure dose: 2.59mSv	-	-
'13.04.16	2	Investigation of the MSIV Room on the First Floor of Reactor Building (Visual inspection, Dose rate, Temperature/humidity, Dust density)	Maximum exposure dose: 0.55mSv (Robots: 5.7mSv(Quince 2), 12.5mSv (Packbot))	7mSv	11 (at the site)
'13.06.18	2	Survey on Upper Space in 1st Floor of Reactor Building (Dose rate, visual verification (conditions of obstacles))	Maximum exposure dose: 0.98mSv (Robots: 38.5mSv (High-access survey robot), 41.0mSv (Packbot))	2mSv	7 (at the site)
'13.07.08	2	Soundness Inspection of Unit 2 TIP Guide Pipe (1st Day, Line B)	Maximum exposure dose: 0.97mSv	3mSv	-
'13.07.09	2	Soundness Inspection of Unit 2 TIP Guide Pipe (2nd Day, Line D)	Maximum exposure dose: 0.72mSv	3mSv	-
'13.07.10	2	Soundness Inspection of Unit 2 TIP Guide Pipe (3rd Day, Line C)	Maximum exposure dose: 0.60mSv	3mSv	-
'13.07.11	2	Soundness Inspection of Unit 2 TIP Guide Pipe (4th Day, Line A)	Maximum exposure dose: 0.77mSv	3mSv	-
'13.07.19	2	Additional Work in Soundness Inspection of TIP Guide Pipe (Line D)	Maximum exposure dose: 1.27mSv	3mSv	-
'13.07.23	2	Survey on the PCV Penetration Vicinities at High Places in the 1st Floor of Reactor Building (Dose rate measurement, and visual verification (conditions of obstacles))	Maximum exposure dose: 0.74mSv (Robots: 43.9mSv (High-access survey robot), 46.3mSv (Packbot))	2mSv	8 (at the site)
13.08.05 -8.09	4	Inside Investigation of the Reactor Well, the RPV and the SFP (Confirmation of debris distribution etc.)	Maximum exposure dose: 0.19mSv/day	2mSv/day	about 30/day

("-" shows that data are not shown in the referrence)

(Summarized by ATC)

• Review of radiation exposures
• Example of exposure dose during the work
• Exposure dose distribution