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31. Prevention of health hazards due to ionizing radiation
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Radiation and radioactive substances are used in a wide range
of areas, including medical diagnosis and therapy, non-destructive inspection,
energy use, etc.
On the other hand, since the bad influence of their use on
the human health is not small, exposure control and health care of workers
must be sufficiently ensured, and employers are obliged to do the following:
(The Ordinance on Prevention of Ionizing Radiation Hazards)
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1. Types of ionizing radiation, etc. (Ordinance, Article 2)
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| a. |
Ionizing radiation
| (a) |
Alpha-rays, deuteron rays, and proton rays |
| (b) |
Beta rays and electron beams |
| (c) |
Neutrons |
| (d) |
Gamma rays and X-rays |
|
| b. |
Radioactive substances (excluding solid substances with a concentration
of less than a specific level, and hermetically-sealed substances)
| (a) |
Strontium 90 or isotopes which emit alpha rays (excluding thorium and uranium):
those more than 3.7 kBq |
| (b) |
Isotopes emitting radiation with a half-life of more than 30 days (excluding
hydrogen 3, etc.): those more than 37 kBq |
| (c) |
Isotopes emitting radiation with a half-life of 30 days or less (excluding
fluorine 18, chromium 51, etc.): those more than 370 kBq
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| (d) |
Hydrogen 3, beryllium 7, carbon 14, chromium 51, germanium 71, thallium
201, thorium or uranium: those more than 3.7 MBq
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|
| c. |
Radiation work (Annexed Table 2 of Enforcement Order of Industrial Safety
and Health Law)
| (a) |
Using or inspecting X-ray equipment |
| (b) |
Using or inspecting a cyclotron, betatron, etc.
|
| (c) |
Degassing or inspecting an X-ray tube or Kenotron
|
| (d) |
Handling an apparatus equiped with a radioactive substance
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| (e) |
Operating a nuclear reactor |
| (f) |
Mining nuclear raw material in a pit |
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2. Setting controlled areas, etc
|
| a. |
An area threatening to exceed 0.3 mSv per week should be set as a controlled
area and indicated as such with a sign. (Ordinance, Article 3)
|
| b. |
The dose to which a worker in the area is exposed, should not exceed 50 mSv per year. (Ordinance, Article 4)
For a pregnant woman, the dose exposure during the period up
to childbirth should not exceed 10 mSv. (Ordinance, Article 5)
|
| c. |
Even in the case where emergency work is carried out due to the occurrence
of an accident, the dose must not exceed 100 mSv. (Ordinance, Article 7)
|
| d. |
For every worker engaged in radiation work or every worker engaged in emergency work, the exposure dose must be measured. (Ordinance, Article 8)
|
|
The records of measurement results and calculation results
of exposure doses (gamma rays, etc.) should be preserved for five years.
(Ordinance, Article 9) |
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3. Protection from external radiation
|
| a. |
When indirect or direct radioscopy is carried out using X-ray equipment,
a room should be established exclusively for this use, and a plate, or
similar apparatus, should be installed for shielding against unnecessary
X-rays. (Ordinance, Articles 10 to 16)
|
| b. |
No admittance area should be established. (Ordinance, Article 18)
|
| c. |
The gamma rays radiation equipment for transmission photography should
be voluntarily inspected at least once a month, and the records should
be preserved for three years. (Ordinance, Articles 18-5 to 18-7)
|
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4. Prevention of contamination
|
| a. |
A non-hermetically-sealed radioactive substance should be handled in a room exclusively for this use. (Ordinance, Articles 22 and 23)
|
| b. |
For work involving emitted radioactive gas, vapour, or dust, local exhaust equipment, or similar equipment, should be installed, and employers should let every worker use protective equipment such as a hose mask. (Ordinance, Articles 24 and 38 to 41)
|
| c. |
If a powdery or liquid radioactive substance spills, the area should be indicated, and the contaminant should be removed. (Ordinance, Article 28)
|
| d. |
A contamination examination area should be established at the exit of a radioactive substance handling room, in order to inspect for contamination of workers. (Ordinance, Articles 31 and 32)
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5. Emergency measures
|
| a. |
In the case where an accident occurs, the employer should immediately evacuate workers from an area with an effective equivalent of more than 15 mSv. (Ordinance, Article 42)
|
| b. |
When an accident occurs, it should be reported to the Chief of the competent
Labour Standards Inspection Office concerned. (Ordinance, Article 43) |
| c. |
Employers should let every worker who remained in an area where an accident
occurred consult a doctor for diagnosis or treatment. (Ordinance, Article
44)
|
| d. |
Employers should examine the exposure state, etc. of every worker who remained
in an area where an accident, and the records should be preserved for five
years. (Ordinance, Article 45)
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6. Operations chief
|
| a. |
For work using X-rays (excluding medical services, etc.), an operations
chief should be appointed from those who have a license for operations
chief of work with X-rays. (Ordinance, Article 46)
|
| b. |
For transmissive photography with gamma rays, an operations chief should
be appointed from those who have a license for operations chief of transmissive
photography with gamma rays. (Ordinance, Article 52-2) |
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7. Special education, etc.
|
| a. |
Employers should specially educate every worker who is engaged in work
using X-rays or gamma rays radiation equipment. (Ordinance, Article 52-5)
|
| b. |
For every controlled area, the working environment should be measured at
least once a month, and the records should be preserved for five years.
(Ordinance, Articles 53 to 55) |
| c. |
Employers should let every worker who enters a controlled area undergo
health examinations at the time of employment, at the time of job transfer,
and at least once every six months thereafter (three months for cataract
and skin), and the records should be preserved for five years. Furthermore,
the results of the health examinations should be reported to the Chief
of the competent Labour Standards Inspection Office concerned. (Ordinance,
Articles 56 to 58) |
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(The next article in this series covers the safety of boilers and pressure
vessels.)
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