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

Session 41 Abstracts
One of the challenges related to such equipment is to consider two routes for the waste management: one for the highly activated
segments and another for the less activated segments.
The length of the segments has been defined to minimize the volume of highly activated waste and therefore develop a process
which is adapted to the size of containers specified by the customer. A model with five cutting operations and generating six segments
has been chosen.
In order to minimize risks and ensure safety for people and facilities, radiological studies were performed for various configurations.
All…
2) ASSAY OF PLUTONIUM CONTAMINATED WASTE BY GAMMA SPECTROMETRY (wP-59039)
Ian Adsley, Michael Green, Ian Pearman, Mike Davies, Nuvia Limited (UK)
The extreme toxicity of plutonium necessitates the segregation of plutonium contaminated materials (PCM) with extremely
small (sub-?g) levels of contamination. The driver to accurately measure these small quantities of plutonium within (relatively)
large volumes of waste is (in part) financial. The range of waste costs in the UK varies considerably typically by an order of magnitude
for each step in category from Exempt, through VLLW, LLW and ILW.
Within the UK, there has been a historical reluctance to use low energy gamma radiation to sentence PCM because of the potential
for self attenuation by dense materials. This is unfortunate because the low-energy gamma radiation from PCM offers the only
practicable technique for segregating PCM within the various LLW and sub-LLW categories. Whilst passive neutron counting techniques
have proved successful for assay of waste well into the ILW category, a cursory study of the neutron yield data from spontaneous
fission and ?-n reactions reveals that these techniques are barely capable of detecting mg quantities of plutonium let alone
the sub-?g quantities present in LLW.
This paper considers the use of two types of gamma detector for assay of PCM: the thin sodium iodide FIDLER (Field Instrument
for the Detection…
3) REUSE OF CONDITIONAL RELEASED MATERIALS FROM DECOMMISSIONING; A REVIEW OF
APPROACHES AND SCENARIOS WITH LONG-TERM CONSTRUCTIONS (w/oP-59149)
Vladimír Daniska, Jozef Pritrsky, Frantisek Ondra, Ivan Rehák, Matej Zachar, DECOM, a.s,;
Vladimir Necas, Slovak University of Technology (Slovakia)
Paper presents the overall scope and actual results of the project for evaluation of representative scenarios for reuse of conditionally
released materials from decommissioning. Aim of the project is to evaluate the possibilities of reuse of conditionally
released steels and concrete in technical constructions which guarantee the long-term preservation of design properties over periods
of 50-100 years. Interaction of conditionally released materials with public is limited and predictable due to design and purpose
of selected constructions and due to fact that in many scenarios these materials are embedded in non-radioactive materials
such as bars in reinforced concrete. Workers scenarios for preparation, operation and maintenance of these constructions are
analysed in detail including the manufacturing of elements for these constructions. Project aims to evaluate the scenarios of reuse
of conditionally released materials in a complex way in order to develop the data for designers of scenarios and to evaluate the volumes
of conditionally released materials based on facility (to be decommissioned) inventory data. The long-term constructions considered
are bridges, tunnels, roads, railway constructions, industrial buildings, power industry equipment and others. Evaluation
covers following areas:
• Analysis of activities for manufacturing of reinforcement bars, rolled steel sheets and other steel elements and…
4) REMEDIATION OF A VENTILATION DUCT CONTAMINATED BY PA-231 (wP-59248)
Pete Burgess, Nuvia Ltd; Clare Irving, Forest Environmental; Keith Stevens, Nuvia Ltd, (UK)
Cambridge University had worked in the 1960s and 1970s with Pa-231, a decay product of U-235. The fume cupboards discharged
into ventilation ducting made from asbestos cement. The university wished to refurbish the laboratory and the RPA had
negotiated over many years with the Environment Agency to set up a project to remove the ducting both to reduce the radiological
hazards and as part of a programme to ,remove unwanted circuits and upgrade the ventilation system to modern standards. Contamination
levels were significant and low dose rates were measurable on the external surface. The aim was to be able to remove
the ducting and treat it as asbestos waste, rather than to have to treat the debris as asbestos contaminated radioactive waste. The age
of the contaminant was such that a large fraction of the decay chain had grown in, giving a mixture of alpha, beta and gamma emissions.
The most useful nuclides for surface monitoring were Pb-211 and Tl-207, both of which are energetic beta emitters. A wide
energy range beta detector was used, but it was fitted with a filter to absorb any alpha radiation which otherwise would have contributed
to the signal for good surfaces but not…
5) MEASUREMENT OF PLUTONIUM CONTAMINATION THROUGH PAINT USING A FIDLER PROBE (wP-59250)
Robert Clark, Pete Burgess, Nuvia Ltd; Ian Croudace, GAU-Radioanalytical Laboratories (UK)
Alpha contamination detection usually relies on good surface conditions - smooth, clean and flat. However, in many circumstances,
this is not the case, or it may be that there is a significant chance that contamination has been deliberately or accidentally
painted over. The alpha emitting isotopes of plutonium also emit significant L x-rays in the 11 to 20 keV energy range, as does Am-
241, which also emits a 60 keV gamma with a 36 % probability. These X-rays are unattenuated to any extent in air over a range
of 1 metre. They also penetrate paint significantly. The Fidler probe was designed as an efficient detector of these X and gamma
radiations. The window is thin beryllium and the scintillator is thin sodium iodide. This leads to a very efficient detection of both
the X-rays in question and the 60 keV gamma radiation while keeping the background as low as possible. The signal from such a
detector can be processed in several ways gross counting above a threshold, counting in regions of interest or full spectrometry.
The advantages of the latter include the minimisation of background, easy background correction, the ability to look at the recorded
X-ray spectrum and the…
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