The integrated disposal system was developed to make sure the disposal of wastes concerning positron emission tomography to comply with the regulations. The system consisted of a management system concerned with the data of wastes and a measurement system concerned with the residual radioactivity of wastes. The information of wastes was stored into the tags. The tags were pasted on the top surface of the container holding wastes. The tag's data was read by the reader. The reader was placed on the base and side surfaces in order to evaluate the dependency of the kind and volume of wastes respectively. The rate at which the reader succeeded in reading was researched. The successful rates in reading depended on the position of the tags and readers. The detection limit of the system was evaluated with the source 99mTc to be 218 Bq. The specific period for decay from 218 Bq to one atom of 18F was estimated to be 39 hours.
Potassic chemical fertilizers contain potassium, a small part of which is potassium-40. Since potassium-40 is a naturally occurring radioisotope, potassic chemical fertilizers are often used for demonstrations of the existence of natural radioisotopes and radiation. To fabricate radiation sources as educational tools, the compression and formation method developed by our previous study was applied to 13 brands of commercially available chemical fertilizers containing different amounts of potassium. The suitability (size, weight, and solidness) of thus fabricated sources was examined and 12 of them were selected as easy-to-use radiation sources at radiation educational courses. The radiation strength (radiation count rate measured by a GM survey meter) and potassium content of the 12 sources were examined. It was found that the count rate was wholly proportional to the percentage of potassium, and a new educational application was proposed and discussed for understanding that the substance emitting radiation must be the potassium present in the raw fertilizers.
A homemade style of air proportional counter was constructed for exercises on radiation for technical staffs that belonged to Graduate School of Engineering, Osaka University. The counter successfully detected alpha-rays from the same type of mantle that was used as a radiation source for a well-known educational experiment with a cloud chamber, which had been performed just before radiation exercises with the counter. Without any special instrument for radiation measurement, pulse signals from the counter were well analyzed with a digital oscilloscope and a personal computer that were widely used for various purposes. Although results and data on such homemade style of educational radiation experiments were rough, discussions on them among trainees were sufficiently effective in the promotion of their understanding of radiation and its measurement.
We changed the purging tanks into the ground type from the underground type, because we could not check a leakage of radioactive wastewater from the underground purging tanks by visual inspection. At the drainage in our radioisotope facility, the wall of underground purging tanks were reused as a protective wall in leakage of radioactive wastewater, and new purging tanks were built in the place among the protective wall. The new tanks are made of stainless steel, and its surface condition can be checked by visual inspection. The process of the construction was divided into the three terms since the radioisotope facility couldn't be closed during the construction. The kinds and quantities of radioisotopes which can be used in our radioisotope facility were reduced because the treatment capacity of the drainage was decreased during the construction. We made efforts especially to prevent a radiation accident during the construction. As the result, it is realized again that a person of radiation control duties plays an important role to prevent the accident when a contamination test or trial run of the system are conducted, heavy things are being carried, or the underground purging tanks are being dismantled.