Radiation safety training courses are indispensable educational programs for radiation workers. We have two kinds of courses, which are held before use of radioisotope (beginner's training course) and held annually (re-training course). The interval between two courses was found to give some effects for radiation worker's recognition and knowledge on radiation safety through the result of examination and questionnaire on the radiation safety after training. The average scores of participants indicated that the short interval (3months) was better than the long interval (almost one year). Furthermore, the average scores of participants in the 2003 training course were higher than those in the 2002 and 2001 training courses. Several participants were found to lack in the basic radiation safety attitude and knowledge. In order to improve these results, the practical training should be given additionally for workers, who lacked in understanding.
A test for checking knowledge about radiation safety management was introduced to the education and training course for radiation workers. The radiation workers were guided to solve some questions during the lecture with checking the answers using textbook. It is expected that they could understand more effectively the important points as radiation worker by the test. The results are fairly good, although sometimes the score distributes from high score to low one. It was found that the score of the test, especially the questions concerning the laws and regulations of safety management, might be related with the attitude at the lecture.
Radiation safety training courses in School of Engineering, The University of Tokyo, were introduced. The number of radiation workers and the usage of radiation and radioisotopes have been surveyed for past 14 years. The number of radiation workers in School of Engineering has increased due to the treatment of X-ray analysis of materials, recently. It is important for workers to understand the present situation of School of Engineering before the treatment of radiation and radioisotopes. What the supervisor should tell to radiation workers were presented herewith. The basic questionnaires after the lecture are effective for radiation safety trainings.
Questionnaires relating to the usage of hand-foot-clothes radiation monitor and the safety handling of wastes were carried out in the education and training course for radiation workers in 2003 and 2004, in the Institute of Radioisotope Research, Graduate School of Medicine, St. Marianna University. Responses from 77 workers were analyzed. The pattern of the frequency of questionnaire of the hand-foot-clothes radiation monitor usage was almost identical between men and women and between workers in two different radiation-controlled areas. However, there was a statistically significant difference (p<0.01, by the chi-square test) between the two groups of workers; that is, workers who either used radioisotopes or not. Similarly, different patterns in right/wrong responses for the handling of radioactive and non-radioactive wastes were observed between these two groups by the method of quantification 3. Therefore, it is suggested that there is a noticeable difference in the behavior between the two groups. We will take into consideration about these two groups in the future education and training courses.
We have constructed a new management system of education and training for radiation workers using database software on public sale. Individual data of applicants are collected to the system through the on-line application program on the Tokyo Tech LAN server. As medical examination and radiation dose data are added to the individual data, the data set are very useful to check the registration of the applicant as a radiation worker. Also these data can be used for managing a stay time in a controlled area as well as radiation dose.
Radiation workers have to receive the radiation safety training every year. It is very hard for them to receive the training within a limited chance of training. Then, we developed the new training system using the video streaming technique and opened the web page for the training on our homepage. Every worker is available to receive the video lecture at any time and at any place by using his PC via internet. After watching the video, the worker should receive the completion examination. If he can pass the examination, he was registered as a radiation worker by the database system for radiation control.
A unique system for monitoring radioactivity in exhaust gas has introduced to the Radon experiment facility at National Institute of Radiological Sciences (NIRS), which has dual detector sets at the air intake and the terminal exhaust duct. The concentration of radon generated in the facility could be evaluated from the difference in the count rate between two detectors. Under ventilation, the radon concentration of both outdoor and exhaust air was almost same, and the equilibrium-equivalent concentration (EEC) was estimated to be nearly 0 Bq m-3. When the air conditioner was halted, radon EEC in exhaust air became slightly lower than that in outdoor. The difference was estimated to be caused by attachment of the radon progeny to the exhaust ducts and sampling ones.
A new computer program for shielding calculation. has been prepared.The program is available for estimating effective doses of photons from radioisotapes, i. e., γ rays and bremsstrahlung X rays emitted by the interaction ofβrays with targets.Main features of the program are as follows: 1) The dose estimation method in the program is the same as the method using effective dose build-up coefficients, Which is given in the manual of shielding calculation for radiation facility. 2) The estimation for any γ-ray and β-ray emitting nuclides can be performed by inputting nuclear data, i. e., γray.energies, γ-ray intensity ratios, β-ray maximum energy and β-decay branching ratio. 3) The estimation for multi-shielding layers of different materials is available. 4) The estimation with different densities of shielding materials and different chemical form of target materials for β rays is available. The computer program has been carefully tested by comparing with the data in the manual of shielding calculation: for radiation facilities, i. e., dose rate, constants and penetration factors of γ-ray and β-ray emitting nuclides. Some equations re-formulated for the dose calculation and the. constitution of the computer program are explained in this paper. The result of the comparison is also discussed, indicating some. differences between the present estimation and the values in the manual.