Radiation protection lessons learned from the TEPCO Fukushima No.1 NPS accident

Figures & data

Figure 1. A typical example representing a time profile of the radiation dose rate observed around the TF No.1 NPS in the early stage of the nuclear disaster. Dotted and broken lines represent the decreasing characteristics of I-131 and the averages of Cs-137 and Cs-134 which were assumed to be existed equally, respectively. The numbers of I, II, III in the figure represent the periods of the high radiation dose rates with rapid change, high radiation dose rates mainly by I-131 deposited on the ground surface, and those by Cs-137 and Cs-134 deposited, respectively.

Table 1. The dose constraints and reference levels used in the ICRP system of radiation protection.

Type of situation	Occupational exposure	Public exposure	Medical exposure
Planned exposure	Dose limit	Dose limit	Diagnostic reference
	Dose constraint	Dose constraint	level^d (dose constraint^e)
Emergency exposure	Reference level^a	Reference level	NA^b
Existing exposure	NA^c	Reference level	NA^b

^aLong-term recovery operations should be treated as part of planned occupational exposure.

^bNot applicable.

^cExposures resulting from long-term remediation operations or from protracted employment in affected areas should be treated as part of planned occupational exposure, even though the source of radiation is “existing.”

^dPatients.

^eComforters, careers, and volunteers in research only.

Table 2. Standard radioactivity limits for foods in Japan and other countries.

Product	Japan	USA	EU	China	South Korea
Water	10		200	–	370
Milk	50		200	330	370
Meat and meat products	100	1200	500	800	370
Fish and fish products	100		500	800	370
Vegetables	100		500	210	370
Baby food	50		–	–	370

Data: Public data released by various governments throughout the world (current as of July 2012). Note that the EU uses the same limits for imported products from Japan as Japan uses.

Figure 2. The conceptual diagram of the determination process of the SRL for general foods. The new SRLs were enforced on 1 April 2012.

Table 3. Distribution of effective dose estimated on the basis of the behavior records of the people living in the preliminary investigation area ^* of Fukushima Prefecture. External effective doses were integrated from 11 March to 11 July 2011.

	Number of the people
	<1 mSv	1 mSv–10 mSv	>10 mSv
The people including those ever engaged in radiation work.	6070	4303	95 (max. 47.2 mSv)
The people excluding those ever engaged in radiation work.	5636	4040	71 (max. 23.0 mSv)
Less than 20 years old.	1032	660	1 (max. 18.1 mSv)

^*Kawamata (553), Namie (7250), Iidate (1944).

Numbers in the parentheses indicate the number of the people responded to the questionnaire excluding radiation workers.

Table 4. Distribution of committed effective doses of the people living in Fukushima Prefecture measured by whole body counters from June 2011 to May 2013. The age of 108,112 people of the total (132,011) is 4–19 years old.

	Committed effective dose
	<1 mSv	1 mSv	2 mSv	3 mSv
Number of the people	131,985	14	10	2

Table 5. Detriment-adjusted nominal risk coefficients (10⁻² Sv⁻¹) for stochastic effects after exposure to radiation at low dose rate shown in ICRP Publication 103.

Exposed population	Cancer	Heritable effects	Total
Whole	5.5	0.2	5.7
Adult	4.1	0.1	4.2