1The radiation room is that region of the irradiator that is enclosed by radiation shielding and is made inaccessible when the radiation source is in use.

2The term ‘radiation source’ includes radioactive sources and radiation generators. ‘Radiation’ as used in the IAEA safety standards means ionizing radiation.

3Product in this context means the objects or materials that are intentionally irradiated.

4The four categories of gamma irradiator have historically been designated with Roman numerals I–IV. The categories of gamma irradiator should not be confused with the categories used in the IAEA’s Categorization of Radioactive Sources [5], which uses Arabic numerals 1–5.

5In this context the term ‘radioactive source’ may apply to one individual sealed source or collectively to a number of radioactive sources in a source array.

6‘Fully shielded’ means the condition in which the source is stored is such that dose rates in the radiation room are optimized, allowing the room to be occupied by workers.

7The source holder is that component of the irradiator within which the radioactive source is positioned, including any retaining screws, pins, clips, etc.

8The source capsule is the protective envelope of a sealed source which prevents leakage of radioactive material.

9A safety interlock is an engineered device for precluding exposure of an individual, either by preventing entry to the controlled area or by automatically removing the cause of the hazard.

10The term ‘qualified expert’ is used in various places in this Safety Guide without modification. It should be noted that the individual should be a qualified expert in a field (e.g. radiation protection or design and operation of irradiation facilities) that is relevant to the issues being described.

11‘Accounting’ in this context means physically checking that all radioactive sources are present in their intended locations. This may be undertaken by means of an appropriate radiation survey.

12This applies for gamma irradiation facilities only.

13‘Inventorying’ means conducting a campaign to physically check all radioactive sources under the responsibility of a person or organization, by specifically and uniquely identifying each individual source using appropriate means such as serial numbers.

14The product positioning system is the means by which the product is conveyed around the irradiation room and past the radiation source to be irradiated.

15‘Dark current’ refers to a condition in which an accelerator generates radiation when there is no current to the cathode but the accelerating voltage (i.e. a high voltage) is still applied. Electrons may still be emitted from the cold cathode and accelerated, resulting in an electron beam even though there is no current to the cathode.

16‘Disabling the means of producing radiation’ means ensuring either that the source rack cannot be raised from the fully shielded position or, for an accelerator based system, that the high voltage is disabled.

17Radiation shields are structures that have as their primary function the attenuation of radiation emitted by the radiation source to acceptable levels.

18The source pass is the component of the product positioning system that carries the product past the source rack.

19‘Fully vented’ means having the design feature for hollow tools, tubes or control rods for full venting to allow air to escape at a rate sufficient to allow water to flood the immersed section as it enters the storage water pool.

20In some areas, short term power failures of not more than ten seconds occur frequently. In such cases, it could be detrimental to some products if automatic irradiator shutdown were to be actuated as a result of the short term power failures. It is acceptable for means to be provided for preventing unnecessary and avoidable shutdowns of the irradiator under conditions of short term power failure.

21An uninterruptible power supply is a backup power supply that, in the event of power failure or power fluctuations, allows enough time for an orderly shutdown of the system or for a standby generator(s) to start up.