Methodology for the application of probabilistic safety assessment techniques (PSA) to the cobalt-therapy units in Cuba

The applications of PSA techniques in the nuclear power plants during the last two decades and the positive results obtained for decision making in relation with safety, as a complement to deterministic methods, have increased their use in the rest of the nuclear applications. At present a large set of documents from international institutions can be found summarizing the investigations carried out in this field and promoting their use in radioactive facilities. Although still without a mandatory character, the new regulations on radiological safety also promote the complete or partial application of the PSA techniques in the safety assessment of the radiological practices. Also the IAEA, through various programs in which Cuba has been inserted, is taking a group of actions so that the nuclear community will encourage the application of the probabilistic risk methods for the evaluations and decision making with respect to safety. However, the fact that in no radioactive installation has a complete PSA study been carried out, makes that certain methodological aspects require to be improved and modified for the application of these techniques. This work presents the main elements for the use of PSA in the evaluation of the safety of cobalt-therapy units in Cuba. Also presented, as part of the results of the first stage of the Study, are the Guidelines that are being applied in a Research Contract with the Agency by the authors themselves, who belong to the CNSN, together with other specialists from the Cuban Ministry of Public Health. (author)