MAINTENANCE INSTRUCTIONS

Quarterly and annual maintenance for source guide tubes

Tools required for maintenance of source guide tubes:

●A424-9XL mock source assembly to perform function tests after cleaning and inspection.

●Length of clean control cable to push A424-9 XL through a 7ft (2.1m) source guide tube.

●1in-18 tap and 1in-18 die nut for male and female threads of the source guide tubes, if required.

Materials required for maintenance of source guide tubes:

●Solvent: Clean mineral spirits to clean the source guide tubes internally.

●Clean lint-free cloths and detergent to clean the exterior of the source guide tubes.

●Mil-Spec grease, MIL-G-23827B or C, MIL-PRF-23827C (or equivalent radiation resistant grease) to lubricate the swage fittings on the source guide tubes.

●Compressed air source and hand nozzle to blow dry the internal conduit of the source guide tubes.

●3M™ yellow polyvinyl tape (or black polyvinyl electrical tape) for repair of cuts in the source guide tubes.

Source guide tube maintenance

1Clean the exterior of all the source guide tubes thoroughly using clean cloths and a detergent. Remove all of dirt, grease and grime from the yellow polyvinyl source guide tubes and the swage fittings.

2Clean the interior of each source guide tube by pouring 4-5oz (100ml) of clean

solvent into one end. Manipulate the source guide tube back and forth to cause the solvent to wash the interior of the entire length of source guide tube. Pour the solvent into a used solvent container. Refill the source guide tube with clean solvent and repeat the cleaning operation. Repeat this cleaning process until the solvent poured out of the source guide tube into the used solvent container is clean. Use a compressed-air hose to blow out any residual solvent from the source guide tubes. Use of a clean white cloth attached to one end of the source guide tube will trap any debris or residual solvent when blowing out the source guide tubes. Repeat the cleaning process until the cloth ‘trap’ indicates dirt is not present within the source guide tubes.

3Carefully inspect the entire length of each source guide tube for cuts and melted areas. Repairs to cut or melted areas can be accomplished by taping the area with 3M™ yellow polyvinyl tape (or black polyvinyl electrical tape). Taping the damaged area of the polyvinyl sheath will prevent the ingress of water and other liquid that would cause corrosion to the remote control cable. Carefully look and feel for dents and depressions in the source guide tubes. Even a small inward dent in the source guide tube could cause a seized source assembly resulting in emergency operations. A ‘mock’ (Model A424-9XL) source assembly attached to a section of control cable that is pushed through the entire length of source guide tube provides additional confirmation the source guide tube suitable for use.

4Inspect the swage fittings of each source guide tube to ensure the threads are not stripped or galled. If the threads are damaged, the use of a 1in-18 tap or die-nut and oil can be used to clean the damaged area. Using moderate pressure, attempt to twist the swage fitting off the source guide tube. If any movement is possible, remove from service and replace the swage fitting. Inspect the source guide tube near the swage fitting for breaks and bulging, remove from service and send to a service center for repairs. Repair can be accomplished by cutting away the damaged area and replacing the swaged fitting. Inspect the exposure head (source stop) to for excessive wear or perforations on the end-stop and the side where the collimator (beam limiter) is mounted. Damaged fittings or exposure heads on source guide tubes can be replaced at an AEA Technology QSA service center. If the swage fittings are not damaged and are securely attached to the source guide tube, apply a light coat of grease to the threads and install the protective covers over the fittings.

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