ICEM11 Final Program 9.7.11pm_ICEM07 Final Program ... - Events

Abstracts Session 39
referred to as a -carbonation and leads after a period of time to significant reduction of the alkalinity (to pH as low as 8.5) followed
by destruction of passive layer and starting corrosion of the embedded steel. The analytical principles and a set of input data have
been implemented into a mathematical model developed by means of GoldSim software. The paper presents the results of mathematical
simulation of corrosion precess, which are compared with real measured values.
A-7) DECOMMISSIONING OF THE UF6 SPHERE (w/oP -59200)
Sylvain Chevassu, ONET Technologies - ONECTRA (France)
Technically, ONECTRA has started with the decontamination, under containment, with a teleoperated arm. The complete operations
of internal cleaning and radiological controls will be operated with this arm. The internal particles are carried out applying
two distinct processes: first, a mechanical decontamination process (brushing/aspiration), followed by a chemical decontamination
process (pulverization of an acid solution). At the end of internal cleaning, the lower part of Sphere will be cut under containment
with mechanical-cutting tools. An internal radiological map will validate that the final decontamination objectives have been
reached. The final validation of the Spheres internal cleaning will be delivered through the agreement of the safety authority, mainly
based at the end of the operation report.
This safety authoritys agreement will allow the final Spheres dismantling sequence, consisting in outdoor cutting operations
with no containment using oxy-gas cutting processes. The last step consists in building a cover slab under the Sphere. This last step
requires a second agreement from the safety authority.
A-8) DEVELOPMENT OF NUCLEAR FACILITIES PIPING CLEANING
SYSTEM USING MICROBUBBLE (w/oP-59070)
Jongseon Jeon, SangChul Lee, Byoungsub Han, Enesys Co., LTD.;
HakSoo Kim, Nuclear Engineering & Technology Institute; Wisoo Kim, Enesys Co., Ltd. (Korea)
It removes radioactive sludge and corrosion products deposited on the inner walls of the pipes and valves in replacement or
decommission, upon termination of life time, of nuclear power plant or nuclear facility. It lowers a cost of waste treatments taking
advantage of a reduction of quantity of radioactive wastes by treating in classification of the radioactive wastes whose activities are
lower than legal standards.
The cleaning or decontamination methods developed until now have induced a damage on systems while being operated. A
decontamination has been restrained if it was difficult to access physically. We are in development of the cleaning technique for
pipelines by utilizing micro-bubbles in order to improve an efficiency and to prevent from any damage of systems. It aims to conduct
a decontamination for spaces difficult to access there by applying cavitation phenomenon that is generated in collapse of
micro-bubbles. In order to improve an efficiency of the micro-bubble device, the experimental conditions suitable to decontamination
have been established and the auxiliary equipments have been added. The generation conditions and characteristics of microbubbles
have been demonstrated by adjusting pHs and temperatures of cleaning solution. A decontamination effect has been confirmed
by adding up an electrolytic method and ozone into micro-bubbles.
A-9) A MATRIX INVERSION METHOD FOR GAMMA-SOURCE MAPPING
FROM GAMMA COUNT DATA (wP -59082)
Richard Bull, Claire Burgess, Ian Adsley, Nuvia Limited (UK)
Gamma ray counting is often used to survey the distribution of active waste material in various locations. Ideally the output
from such surveys would be a map of the activity of the waste. In this paper a simple matrix inversion method is presented. This
allows an array of gamma-count data to be converted to an array of source activities.
For each survey area the response matrix is computed. The elements in this matrix are calculated using a gamma shielding code
such as MicroShield (1). This matrix links the activity array to the count array. The activity array is then obtained via numerical
matrix inversion. The method was tested on artificially created arrays of count data onto which statistical noise had been added.
The method was able to reproduce, quite faithfully, the original activity distribution used to generate the dataset.
The method has been applied to a number of practical cases, including the distribution of activated objects in a hot cell and to
activated nimonic springs amongst fuel-element debris in vaults at a nuclear plant.
Reference
1) MicroShield, Version 8, Grove Software, 2009.
A-10) DECOMMISSIONING ACTIVITIES FOR SALASPILS RESEARCH REACTOR (wP -59055)
Andris Abramenkovs, Latvian Environment, Geology and Meteorology Centre;
Jazeps Malnacs, State Environmental Service (Latvia)
In May 1995, the Latvian government decided to shut down the Salaspils Research Reactor (SRR). The reactor is out of operation
since July 1998. A conceptual study for the decommissioning of SRR has been carried out by Noell-KRC-Energie- und
Umwelttechnik GmbH at 1998-1999. The Latvian government decided to start the direct dismantling to green field” in October 26,
1999. The upgrade of decommissioning and dismantling plan was performed in 2003-2004 years, which change the main goal of
decommissioning to the brown field.
The paper deals with the SRR decommissioning experience during 1999-2010. The main decommissioning stages are discussed
including spent fuel and radioactive wastes management. The legal aspects and procedures for decommissioning of SRR are
described in the paper. It was found, that the involvement of stakeholders at the early stages significantly promotes the decommissioning
of nuclear facility.
Radioactive waste managements main efforts were devoted to collecting and conditioning of historical radioactive wastes from
different storages outside and inside of reactor hall. All radioactive materials (more than 96 tons) were conditioned in concrete containers
for disposal in the radioactive wastes repository Radons at Baldone site. The dismantling of contaminated and activated
components of SRR systems is discussed in paper. The cementation of dismantled radioactive wastes in concrete containers is discussed.
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