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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 18:02 |
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Conference: Bucharest University Faculty of Physics 2017 Meeting
Section: Atomic and Molecular Physics. Astrophysics. Applications
Title:
Characterization of gamma emitters radionuclides in magnetite waste containers at CANDU stations
Authors:
Alexandru Emilian NEDELCU(1,2), Alexandru CHIROSCA(3), Octavian SIMA(3)
*
Affiliation:
1) CNE Cernavoda, Romania
2) Doctoral School of Physics, Faculty of Physics, University of Bucharest, Romania
3) Faculty of Physics, University of Bucharest, Romania
E-mail
anedelcu@cne.ro
Keywords:
CANDU, reactor, gamma-spectroscopy, corrosion, fission, efficiency calibration, dose
Abstract:
Recently, in some CANDU nuclear stations (Cernavoda, Point Lepreau), removal of magnetite deposits from Steam Generators of PHT (Primary Heat Transport) was performed in order to improve the heat transfer factor and to reduce the overall power production. As a consequence, a significant amount of radioactive waste consisting of bulk magnetite has to be properly managed. Further management plans would require accurate characterization and evaluation of radioactivity inventory retained by magnetite deposits.
The In-Situ Gamma spectrometry measurement techniques combined with dose rate measurements along magnetite waste containers profiles proved to be the most adequate way to achieve the following objectives:(1) evaluation of gamma emitters activity build-up on PHT System components; (2) optimization in operation of purification systems (time of operation, size of filtration); (3) understanding of correlations between PHT chemistry changes and radionuclides activity transport in PHT system; (4) obtaining data in order to establish appropriate methodologies for treatment and conditioning of radioactive magnetite waste.
The measurement methodology presented in this paper was tested at Cernavoda NPP in December 2016 and it includes: (1) gamma dose rate measurements (by using FH 40 GL-10 and FHZ 632 L-10 proportional counters used for highly sensitive dose rate measurement of X-ray and gamma radiation, developed by Thermo ScientificTM) along the profile of magnetite waste containers to determine the spatial distribution of gamma radiation fields; (2) in-situ gamma spectroscopy measurements (by using INSPECTOR 2000, a HPGe detector based system developed by Canberra) to determine gamma emitters activity retained in the filter; system efficiency calibration has been performed by ISOCS simulation software.
The measurement results indicate a non-uniform distribution of both gamma dose rate and gamma emitters activity along the profile of magnetite waste container. A dominant contribution of insoluble activated corrosion products (eg: Zr-95, Nb-95, Co-60) has been observed.
References:
1. COG-06-3065 „A Guide to Radiation Sources and Radiation Source Terms in CANDU Reactors During Normal Operation”, G. Gomes, CANDU Owners Group Inc., May 2008;
2. COG-00-087R1 "Activity Transport Manual for the CANDU Heat Transport System", D.A. Guzonas, January 2013
Acknowledgement:
N/A
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