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Case No.4

Skin exposure to hazardous radiation during X-ray leakage tests

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[Circumstances of Incident]

An inspector was suffered hazardous radiation exposure to his skin while conducting X-ray leakage tests at the final stage in the manufacture of an X-ray device.

The company carried out pre-shipment tests of manufactured X-ray devices in a controlled area within the plant. Detailed inspections were conducted in terms of both hardware and software in accordance with the checklist developed by the company.

On the day of the accident, the victim was engaged in pre-shipment tests on X-ray diffraction devices in the test area described above.

The victim started X-ray leakage tests from at bout one o'clock in the afternoon. He released a fail-safe mechanism (which turns off the X-ray power supply switch if the operator opens the front door of the device), and measured X-ray leakage with a survey meter after confirming that X-ray radiation is continuing. At 1:30 in the afternoon, as X-ray leakage exceeding the permissible standard was detected near the right shutter. When he tried to inspect the shutter that covers the X-ray generator unit, his right hand was exposed to hazardous radioactive X-ray radiation.  


The direct causes of this accident may be attributed to the victim's actions. He released the fail-safe mechanism of the X-ray generator and inserted his right hand into the radiation path to remove the shutter covering the X-ray source.

This operation involves high risks, as the test must be conducted after releasing the fail-safe mechanism  which contrasts with the operation by end users. For this reason, operational standards must be established in advance for trouble involving the shutter (for example, procedures to remove the shutter). However, such standards were not adopted by this workplace .

The indirect causes of this accident relate to daily operational practices in this plant. As inspectors had to handle a large number of inspections in professional areas, they are assumed to have paid less attention to the dangers of X-ray radiation.

[Type of business] Other precision machines/equipment manufacturing
[Type of accident] Contact with hazardous substances, etc.
[Number of victims] One injured (involving absence from work)