Radiological impact from the removal of sources from a radioactive waste disposal

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Abstract

Abstract. In a radium storage facility of Umicore at the Olen site, a variety of wastes, consisting of uranium mill tailings and other radium-rich and radium-low tailings, have been disposed of in a number of 120 cells in a heavily engineered repository. In 8 of these cells also radium sources are stored, comprising radium needles, radium salts and radium-beryllium neutron sources. These cells have been filled with concrete after the introduction of the sources. The presence of such sources in a surface disposal unit of radioactive waste however, is unwanted from the viewpoint of current regulations. Therefore and on demand of Umicore, the reduction of the radiological impact to the population from the removal of the sources out of the facility was assessed and compared with the dose impact to the workers executing this removal. The radiological impact to the population was assessed for normal (NES) and alternative evolution scenarios (AES). Yet, the NES did not give rise to any significant individual dose to the critical group, with or without the sources present. Only the AES related to constructions, residence, core-drilling and degradation of barriers, did. Among these scenarios, only core-drilling gave rise to maximum doses that were influenced by the presence of the sources. As a consequence the dose savings to the critical group in the drilling scenario, due to the removal of the sources, were to be compared with the dose to the workers executing this removal. The presence of the sources in the storage facility gave rise to a maximum effective individual dose of 146 mSv to the critical group in the core-drilling scenario. The individual dose required from the workers executing the removal of the sources is approximately as high (135 mSv). However the removal of the sources was assumed to require 8 workers, resulting in a collective dose of 1.1 manSv, while the critical group for the drilling scenario could consist of 4 persons, resulting in a collective dose saving to the population of 0.6 manSv. In order to be able to compare the potential impact to the critical group of the population with the actual impact to the workers, the former has to be multiplied with the probability of occurrence of the drilling scenario. In this way the collective and individual radiological risk for the critical group will be lower by several orders of magnitude than those for the workers. From an ALARA point of view, the removal of the sources from the storage facility does not seem to be justifiable.

Details

Original languageEnglish
Title of host publicationProceedings from "The 2nd International Conference on Radioactivity in the Environment"
Place of PublicationOsteras, Norway
Pages664-667
StatePublished - 2 Oct 2005
EventThe 2nd International Conference on "Radioactivity in the Environment" - Nice, France

Conference

ConferenceThe 2nd International Conference on "Radioactivity in the Environment"
CountryFrance
CityNice
Period2005-10-022005-10-06

Keywords

  • assessment, radiological optimization, radioactive waste, radiological impact, radium, waste disposal

ID: 121341