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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:13 |
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Conference: Bucharest University Faculty of Physics 2011 Meeting
Section: Nuclear and Elementary Particles Physics
Title:
The methodology used to estimate the radioactive inventory of the VVR-S Magurele nuclear reactor
Authors:
Evelina Ionescu (1,2), D. Stanga (1), O. G. Duliu (2)
Affiliation:
Horia Hulubei National Institute of Physics and Nuclear Engineering, Magurele (Ilfov), P.O.Box MG-6, RO-077125, Romania(1)
University of Bucharest, Department of Atomic and Nuclear Physics, Magurele (Ilfov), P.O.Box MG-11, RO-077125, Romania(2)
E-mail
eionescu@nipne.ro
Keywords:
Decommissioning; radiological characterization; free release.
Abstract:
According to national and international standards of nuclear domain, all nuclear plants at the end of their life, must past the conservation stage and subsequently scrapped. Decommissioning activities consist of systematic and progressive reduction of radioactive and non-radioactive materials inventory by complex technical and administrative actions, planned and controlled rigorously, to release the nuclear installations under the authorization requirements for nuclear facility in terms of nuclear safety and radiological assurance as well as to protect the health decommissioning personnel, population, ownerships and the environment. The decommissioning activities are radiological and non-radiological risk operations, which must be justified and kept to the lowest level cost possible, and without unpredictable situations that may delay the decommissioning process development. An important step in the decommissioning process consists of the radioactive inventory estimation whose principal component is represented by the activated construction materials. In the case of VVS-S nuclear reactor of the National Institute of Physics and Nuclear Engineering, the main components of its block consist mainly of four materials: aluminum, cast iron, concrete and graphite. Measurements and sampling were performed in specified regions of the reactor block to provide an experimental basis for the future characterization as well as to evaluate the most suitable strategy to use the historical information regarding reactor operation. Measurements of radiation fields can provide an acceptable estimate of the activity if the relationship between activity content and radiation field is well established. These measurements were made at fixed, convenient distances, with respect to both internal or external source of contamination. However, gross radiation readings alone does not indicate the nature and quantity of each of the major isotopes in a given material unless, a detailed analysis is performed in order to derive isotopic concentrations comparable with total radiation readings. By taking into account the experimental uncertainties, the characterization could be considered complete only when a sufficient volume of information is collected.
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