Extrusion Asia Edition 1-2020

HCH. KÜNDIG & CIE. AG Joweid Zentrum 11, 8630 Rüti ZH, Switzerland www.gauge.ch Radiation Safety The introduction of the K-XRAY Rotomat KT system for thick- ness measurements undoubtedly reduces radiation safety re- quirements, since radiation exposure risks are significantly lowered. Most of the countries have certain rules and regulati- ons for the operation of an open source X-ray radiator. These rules need to be clarified by the customer with the local autho- rities associated with the installation country. The following sec- tions describe shielding and safety devices, emergency scena- rios, and exposure doses. Shielding and safety devices The peak voltage of the K-XRAY tube is 19 keV. This voltage re- lates to the maximum energy of the X-ray beam. The average energy is less than 15 keV. This energy is very low in compari- son to medical X-Rays performed on an adult person, where voltages are almost 100 keV for a thorax exposure, 40 keV for hands and 30 keV for the chest. Since the K-XRAY radiation energy is very low and the beam is narrow, the shielding is inexpensive and easy to install. It is made by normal iron or steel with a thickness of about 1 mm and max. 1 m high, depending on the source-protected area distance. A metal door (not shown) allows easy access for maintenance. Under normal conditions, the door is interlocked with the sys- tem X-Ray energy source, powering it OFF automatically when the door is opened. A double safety warning light (red and green) installed outside the shielded area to continuously in- form workers about the system condition (X-ray ON/OFF). Out- side of the shielding working areas are X-ray free areas, without any requirement for radiation protection or monitoring. Emergency scenarios With the K-XRAY system, there are no emergency scenarios to be considered, since powering OFF the system instantaneously eliminates any radiation. On the contrary, when using radioacti- ve sources like Kr-85 or Am-241, assessment of emergency sce- narios is required. Using continuous radioactive sources, the companies must implement a system for assuring sources are not affected by any fire or other accident and, in some cases, an emergency team must be organized. Maintenance and Transport The maintenance of a radioactive source is typically an activity that imparts higher doses than during normal operations. In fact, maintenance people could be exposed to doses as high as 10-20 uSv/h. For maintenance on the K-XRAY, the X-Ray source is powered OFF; i.e., the X-rays disappear instantane- ously after turning OFF the equipment. There is also no residual radiation from the X-Ray source nor contamination of the sur- rounding areas. The safety interlock on the access door assures that worker cannot enter the radiation area when the beam is ON. Finally, for shipping and general transportation, the K- XRAY system doesn’t have any restrictions as it is a standard piece of electronic equipment without any constraint. This is because with no power source during transportation, it is im- possible for the X-ray tube to emit radiation at any level. Worker doses Since K-XRAY Rotomat KT energy is very low, emitted radiation cannot reach worker deep organs (the ones that are more sen- sitive to ionizing radiations). The only organs that could be af- fected by its X-rays are the skin and eyes. Because of this, also in case of an overexposure, the expected effective dose is low. During normal activity (worker working on the source line and maintenance) personal doses are insignificant (<0.1 mSv/year) and lower than the individual dose limits stated for the popula- tion in Europe and all over the world (1 mSv/year). Workers are considered non exposed workers. Employer’s duties are simplified, too. They don’t have to organi- ze any personal dosimetry protocols nor arrange for a radiation medical visit. A nuclear radioactive source requires the au- thorization of local authorities, which can be a time-consuming procedure (usually more than 6 months). However, the K-XRAY Rotomat KT only requires the submission of formal documenta- tion to the local authorities, according to the European directive about radiation protection. Conclusion The K-XRAY Rotomat KT system greatly improves the radiation protection standard levels and also simplifies the company’s responsibilities for protecting workers and the population against ionizing radiations. 46 测控技术 Extrusion Asia Edition 1/2020