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IRR99 Guidance - Part 6 - Control of Radioactive Substances

IRR99 (27) - Sealed Sources & articles containing radioactive substances

Where a radioactive substance is used for work requiring ionising radiation, it should be used in the form of a sealed source as far as this is reasonably practicable (i.e. the radioactive material is not dispersible).

The design of any source must be so as to prevent leakage, and:

  • in the case of a sealed source,  prevent leakage so far as is practicable;  or
  • in the case of any other article,  prevent leakage so far as is reasonably practicable

Where it is appropriate, the radiation employer must ensure that suitable tests are made at suitable intervals to detect any leakage. Typically this test (‘leak test' / 'wipe test’) will be in the form of a ‘wipe’ made to the standard required by at least ISO 9978.

A record of these tests must be kept for 2 years after the source is disposed of, or until a further record is made of a subsequent test.

Where testing is appropriate under normal operating conditions the interval between tests should not be more than 2 years.

The Radiation Protection Adviser (RPA) will normally be consulted by the RPS or radiation employee to assist in determining what is ‘appropriate’. For example, it may be appropriate in certain circumstances to extend the testing interval of certain fixed densitometry gauges to meet plant maintenance schedules.

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