2. Radiation Monitoring
On 13 April, deposition of both I-131 and Cs-137 was detected in 2 and 5 prefectures respectively. For both, I-131 and Cs-137, the depositions detected were below 20 Bq/m2 at all stations.
Gamma dose rates are measured daily in all 47 prefectures. The values tend to decrease over time. For Fukushima, on 13 April a dose rate of 2.0 µSv/h was reported. In the Ibaraki prefecture, a gamma dose rate of 0.14 µSv/h was reported. The gamma dose rates in all other prefectures were below 0.1 µSv/h.
Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances beyond 30 km from Fukushima-Daiichi. On 13 April, the values in this area ranged from 0.2 to 26 µSv/h.
In addition to the 7 measurements referred to in yesterday's brief, (note- these measurements were made at distances of 25 km and 33 km not 32 km and 62 km as reported), 13 more measurements were made on 12 April at distances of 25 to 33 km, West and Northwest from the Fukushima Nuclear Power Plant by the IAEA team. At these locations, the dose rates ranged from 0.5 to 16.5 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.05 to 2.1 Megabecquerel/m2.
On 13 April, the IAEA Team made measurements at 7 different locations in the Fukushima area at distances ranging from 32 to 62 km, North and Northwest from the Fukushima Daiichi nuclear power plant. At these locations, the dose rates ranged from 0.35 to 2.6 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.35 to 2.6 Megabecquerel/m2.
Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 13 April that covered a total of 98 samples taken on 4 and 11 to 13 April. Analytical results for 76 of the samples of various vegetables, pork, seafood and unprocessed raw milk in nine prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Miyagi, Niigata, Saitama and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. In Fukushima prefecture on 11 April, twenty samples of various vegetables were above the regulation values set by the Japanese authorities for Cs-134/Cs-137, and one sample of seafood (sand lance) and one sample of spinach were above the regulation values set by the Japanese authorities for both I-131 and Cs-134/Cs-137.
3. Marine Monitoring
TEPCO Monitoring Programme
TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations. (See Map 1: TEPCO Seawater Sampling Locations).
On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.
Until 3 April a general decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase in radioactivity has been reported.
On 11 April decreasing trends for both I-131 and Cs-137 concentrations of two orders of magnitude from near-shore (less than 10 kBq/l) to 15 km off-shore (0.1-0.02 kBq/l) were observed.
On 14 April no new data for TEPCO 1 - 10 sampling points have been reported.
MEXT Off-shore Monitoring Programme
Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map 2: MEXT Seawater Sampling Locations).
On 11 April Cs-137 was only detected at MEXT 4 at a concentration level of about 70 Bq/l. The highest concentration of I-131 (about 90 Bq/l) was also recorded at MEXT4. For other sampling locations I-131 was reported at levels below about 15 Bq/l.
0n 14 April no new data for all MEXT sampling points have been reported.
Map 1: TEPCO Seawater Sampling Locations:
Map 2: MEXT Seawater Sampling Locations:
4. IAEA activities
The 141st Session of the FAO Council will be briefed by representatives of the Joint FAO/IAEA Division on the nuclear emergency in Japan on Friday, 15 April, at FAO Headquarters in Rome, Italy. The briefing will include a general background summary of the emergency, the current situation in Japan, FAO/IAEA/WHO responses and actions taken to date, and future challenges.