Control technology and radiation protection programme

(f)implementation of an appropriate medical surveillance programme (see section 8.4);

(g)assignment of responsibilities, including the necessary authority and resources, to implement and enforce all aspects of the RF protection programme; and

(h)periodic (e.g. annual) reviews of the effectiveness of the programme so that deficiencies can be identified and resolved.

8.1.3. Duties of the worker (user)

Workers in charge of the day-to-day operation and maintenance of RF heaters

must:

(a)understand the hazards associated with operating the specific equipment assigned to them and the controls used to mitigate those hazards;

(b)be aware of, and follow, normal safe operating practices and procedures;

(c)be able to recognize and report RF sealer malfunctions and maintenance problems, particularly with respect to RF controls (e.g. missing fasteners in the RF shield);

(d)report events which may be germane to medical surveillance (e.g. occurrence of RF burns, implanted medical devices such as a cardiac pacemaker, copper IUD, and hip and knee replacement, etc., sensation of non-routine heating, etc.).

8.1.4. Responsibility of manufacturers

RF heater manufacturers are responsible for making equipment that complies with applicable standards, and for providing information on the hazards of operating and servicing the equipment. The information must be sufficient to alert the owner of the magnitude of the risk and the appropriate precautions that need to be taken. It is recommended that the information include RF survey results obtained prior to shipment of the RF heater, for comparison purposes after installation and periodic maintenance.

Manufacturers will strive to minimize RF exposures through the use of integral engineering controls, particularly RF shielding, to minimize RF exposures. Instructions will encourage users to maintain the controls as designed. Manufacturers will also share applicable information useful in retrofitting RF heaters purchased without shielding.

Manufacturers will incorporate interlocks and physical barriers into the design of RF heaters to prevent contact with the high-voltage components as well as with intense RF emissions. Appropriate labels will be attached to the RF heater to warn operators and maintenance persons of areas of potential electrical shock and RF hazards.

8.2. Work practice controls

Although shielding should comprise the primary control of RF exposures, safe work practices, including proper maintenance procedures, can also significantly reduce exposures.

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Safety in the use of RF heaters and sealers

8.2.1. Maintenance procedures

Appropriate work practices must be followed during the repair and maintenance of RF heaters. Occasionally, cabinet panels must be removed by service personnel to allow access to the interior of the heater for maintenance or repair work. This should be done only by persons who are trained to work on this equipment and who are aware of the potential hazards and how to protect themselves. The electrical power to the heater should be disconnected before proceeding with repair. All parts, including shielding, should be replaced before the power is restored to the heater. Maintenance personnel should understand why all the fasteners, cabinet panels, and interlocks of the panels and doors must be properly reinstalled. Failure to replace a panel may allow high levels of RF radiation to escape and allows direct access to 5,000 volts or more inside the generator. Contact with these high voltages is deadly.

RF heaters use interlocks to shut off electrical power when a cabinet panel is removed or a door opened (preventing RF emission or contact with high voltage). The interlocks are vital tools for worker protection. All workers should understand the necessity for interlocks and the need for maintaining them in good working order. Interlocks must not be disabled when a panel is removed or a door opened.

8.2.2. Operator procedures

Heater operator exposure can be reduced by keeping the operator's hands and upper torso as far as practical from the heater (Conover et al., 1994). Thus, administrative controls or physical barriers which maximize the distance between the heater and operator can be effective in reducing exposures. Many of these techniques can be used without decreasing product quality or output.

The operator's control panels for some automated RF heaters are positioned away from the applicator plates, and therefore away from the principal RF source, by using shuttle trays, turning tables or conveyor belts to feed product materials in and out of the RF applicator. These designs were originally introduced to increase efficiency in production, since they allow for loading and unloading at the on position while the other product is being RF heated. However, they often result in reduced exposure due to the increased distance between the operator and the RF applicator. Caution must be exercised so that the shuttle trays or conveyor mechanisms do not become RF energized, thereby increasing operator exposure.

8.2.3. Identification of RF hazard areas

Controlling exposure time and the distance between the RF source and the operator are important in maintaining the workers' exposures below recommended levels. When necessary owing to excessive leakage, "RF hazard areas" must be identified around each heater to alert the workers of areas that are not to be occupied during RF application. The location of the hazard areas must be based on exposure measurements made during maximum field generation and accounting for the highest duty factor (i.e. ratio of RF "on" time during any 6-minute period, assuming intermittent exposure) for which the heater may be used. The RF hazard areas shall be clearly marked with appropriate signs, barricades, floor markings, etc., of sufficient size

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