Fukushima Nuclear Accident

Radiological consequences

28 March 2011

Gamma Dose Rates in µSv/hour15-27 March

Natural Background: 0.1 µSv/hour

0

0.2

0.4

0.6

0.8

1

1.2Ibaraki(Mito)

Saitama(Saitama)

Tokyo(Shinjyuku)

Daily deposition: I-131/ Cs-137Bq/m2

Mar 21-22 Mar 22-23 Mar 23-24

Location I-131 Cs-137 I-131 Cs-137 I-131 Cs-137

Saitama(Saitama) 22000 1600 22000 320 16000 180

Chiba(Ichihara) 14000 2800 22000 360 7700 210

Tokyo(Shinjyuku) 32000 5300 36000 340 1300 160

Ibaraki (Hitachinaka) 85000 12000 27000 420 1200 63

Mar 24-25 Mar 25-26

Location I-131 Cs-137 I-131 Cs-137

Saitama(Saitama) 160 17 91 16

Chiba(Ichihara) 130 23 320 86

Tokyo(Shinjyuku) 173 37 220 12

Ibaraki (Hitachinaka) 480 99 860 160

Permissible limit-Japan: Adult: 300 Bq/l; Children/100 Bq/l

Permissible limit-Japan: 200 Bq/l

On-Site 3 exposed workers medical statusMarch 24 3 workers exposed to radiation (2 with feet/legs contamination)NIRS Hospital

Radiation monitoring:Body dosimeter: 173, 179, 180 mSv(Dose limit for emergency workers in life saving operation: 250 mSv)

Medical conditionTransient redness (suggested a dose between 2000-3000 mSv locally)Under medical observation for 4 days.

Latest news:All 3 patients were discharged (March 28 at 12:00 Tokyo time)2 patients with local legs problems: Regular medical follow-up

Point 26 (30km)

Point 27(33km)

Point 28 (36km)

Point 29 (38km)

Point 30 (41km)

Point 15 (40km)

Point 17 (36km)

Point 18 (34km)

Point 19 (30km)Point 14 (42km)

Point 13 (43km)

Point 8 (46 km)

Point 6 (58km)

Point 25 (24km)

Point 9(29km)

Point 10 (30km)

Point 11 (31km)

Point 12 (32km)

Point 22 (23km)

Point 2 ( 32km)

Point 1 (32km)

Point 3 (41km)

Point 4 (44km)

Point 5 (55km)

Point 23 (16km)

Point 21 (24km)

Point 20

(25km)

Point 24 (19km)

Point 7 (56km)

Fukushima Daiichi NPP

A

BC

D

Measurement locations at Fukushima region

Radiation Measurements• Measurements at 35 locations in Fukushima and

20 in Tokyo and surrounding areas(dose rate & contamination)

• Collected sample swipes, air sampling from around most of the locations (same places, and more — for corroboration)

• Samples will provide more qualitative data and will be disseminated after analysis at Seibersdorf

Radiation Measurements (Cont’d).

• Beta-gamma contamination measurements ranged from 0.02 to 4.9 Megabecquerel per square meter

• Dose rate between 0.05 and 59 microsieverts per hour

• Distance between 16 to 70 kilometers

2011-3-28 10

IAEA Radiation monitoring team

March 28, 1st team • 8 locations in Tokyo region • Gamma-dose rates: 0.08 to 0.13 µSv/hour• Natural background: 0.1 microsivert per hour

March, 28, 2nd team • Radius of 30 to 46 km from the Fukushima NPP• Dose rates from 0.5 to 3 µSv/hour• Beta-gamma contamination: from 0.02 to 0.33

MBq/m2

Monitoring of I-131 and Cs-137 in soilFukushima Prefecture

• Initial measurements: Spatial variability of deposition

• High depositions in some areas

• Further measurements and study are in progress