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

Abstracts Session 27
5) REMEDIATION AND ASSESSMENT OF THE NATIONAL RADIOACTIVE WASTE
STORAGE AND DISPOSAL SITE IN TAJIKISTAN (wP-59110)
Nazirzhon Buriev, Dzhamshed Abdushukurov, Physical-Technical Institute of the Academy of Sciences
of the Republic of Tajikistan; Tjalle Vandergraaf, Providence University College (Tajikistan/Canada)
The National Radioactive Waste Storage and Disposal Site was established in 1959 in the Faizabad region approximately 50
km east of the capital, Dushanbe. The site is located on the southern flank of the Fan Mountains facing the Gissar Valley in a sparsely
populated agricultural area, with the nearest villages located a few km from the site. The site was initially designed to accept a
wide range of contaminated materials, including obsolete smoke detectors, sealed radioactive sources, waste from medical institutions,
and radioactive liquids.
6) INTEGRATING HISTORY AND MEASUREMENT INTO A CASE FOR SITE RELEASE (wP-59131)
Angela Bartlett, Research Sites Restoration Limited; Mike Davies, Pete Burgess, Nuvia Ltd;
Gavin Coppins, Babcock International Group (UK)
The United Kingdom nuclear research programme started in the 1940s. Research Sites Restoration Limited (RSRL) is responsible
for two sites which were at the forefront of this research. These are the 100 hectare Harwell site in Oxfordshire and the 84
hectare Winfrith site on the south coast of England. The work performed on these sites covered a huge range of nuclides, combinations
of nuclides, chemical and physical processes, far more complicated than a power station, for example. The sites have a complex
history with records of hundreds of buildings, many kilometres of drainage systems, groundwater contamination issues and
land areas which require remediation. Formal work towards site release began in the 1990s, but demolition and clearance for reuse
started many years earlier.
An efficient restoration programme requires appropriate quality data. It is vital to decide what you need to know and how well
you need to know it. As part of this, a challenging number of factors need to be considered in its design.
This paper discusses these factors using the examples of the approach used at the Harwell and Winfrith sites including:
• historical knowledge and associated uncertainties
• relevant clearance criteria
• availability and limitations of surveying equipment...
7) CHARACTERIZATION OF A DEEP RADIOLOGICAL CONTAMINATION:
INTEGRATION OF GEOSTATISTICAL PROCESSING AND HISTORICAL DATA (wP-59062)
Yvon Desnoyers, GEOVARIANCES; Patrick De Moura, CEA (France)
Emerging in the early 80s, decommissioning is more than ever a major issue since hundreds of sites and facilities worldwide
will end their operations over the next decades. Decontamination and remediation projects are all the more sensitive since they
could last several years and turn out to be highly costly if not well-prepared. The key lies in an adequate contamination knowledge
which helps to manage the remediation works and optimize the radiological waste production.
The methodologies commonly applied base their recommended decision-process on more or less complex statistical analyses
to validate the remediation target after the waste removal work (guidance for demonstrating compliance with a dose- or risk-based
regulation). These techniques ignore the spatial behavior of the contamination and the importance of sample localization upstream.
The lack of representation and data processing tools leads to inefficient radiological characterizations, which always maximize the
amount of contaminated soils or concrete volumes.
To solve these issues, the French Atomic Energy Authority (CEA) has developed a methodology over the last 10 years with
Geovariances partnership to fulfill the radwaste categorization. This methodology consists of an ordered sequence of evaluation
actions starting with historical and functional analyses, in-situ characterization if relevant using non-intrusive measurement techniques,
...
8) INDUSTRIAL EXPERIENCE FEEDBACK OF A GEOSTATISTICAL ESTIMATION
OF CONTAMINATED SOIL VOLUMES (wP-59181)
Claire Faucheux, Nicolas Jeannée, GEOVARIANCES(France)
Data collected during the sampling of polluted sites are mainly used to characterize the concentration level and, through an
exploratory and variographic analysis, to characterize the spatial variability; at fixed support, to estimate the concentrations in order
to trace pollution map. In the case of kriging, this map is completed by the map of the standard deviation of the estimation error,
making it possible to delimit the zones in which the estimation is considered to lack in precision. If a proportional effect is present
(the local spatial variability depends on the local concentrations mean), the map of error standard deviation has to be corrected to
take into account the increase of spatial variability with the local concentration mean.
A confidence interval can be derived conventionaly from the kriging estimation and the associated error standard deviation.
For a fixed limit threshold, the polluted site can then be divided in three areas:
• the polluted zone, at a fixed statistical risk;
• the not polluted zone, at a fixed statistical risk;
• the zone of uncertainty , in which the estimated concentrations are close to the threshold. Because of the estimation error,
it is not possible to specify if the exact concentrations exceed or not the threshold.
In the case of a soil pollution by hydrocarbons, usual and geostatistical forecasts are compared. The effective consequences of
these various forecasts on the quality of the site remediation are quantified and discussed.
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