The 12th International Conference on Environmental ... - Events

Session 31 Abstracts
<strong>The</strong> aim of the monitoring process is to identify any activity which exceeds the delicensing criteria set by the Nuclear Installations
Inspectorate (NII). <strong>The</strong> relevant criteria are the residual activity and the risk to a future site occupier. <strong>The</strong> maximum missable
activity for each pipe class was determined by considering instrumentation characteristics and natural background radiation
levels. <strong>The</strong> equipment used (a caesium iodide scintillation probe connected to a ratemeter), was limited by the small diameter of
some drains. <strong>The</strong> hypothesis chosen was that residual activity was most likely to lie along the base of the pipe, given that the drains
generally ran with only a limited depth. <strong>The</strong> response was measured for Cs-137 gamma radiation and then used to calculate the net
count rate for a variety of pipe configurations. Variability of the data was investigated in relation to static probe response and variations
in counts per second along a pipe length. Analysis of the data using GIS showed clear spatial patterns, indicating systematic
variability within each pipe material and diameter class.
2) BENEFITS OF LRGS IN ASSESSMENT AND REMEDIATION OF ALPHA CONTAMINATION - 16023
Martha McBarron, Aker Solutions (UK); Jim Cassidy, Fathoms Ltd (UK),
Louise Hutton, Low Level Waste Respository (UK)
<strong>The</strong> legacy of alpha contamination in an exterior disusedstorage area at the Low Level Waste Repository (LLWR) presented
difficult challenges with regard to assessment and remediation. <strong>The</strong> area was heavily overgrown, with degraded remnant surfaces
and debris from past demolition activities. <strong>The</strong> use of conventional field instruments and/or an extensive intrusive sampling programme
were precluded as being impractical, the latter prohibitively costly and not expeditious. This paper describes the identification
of a cost-effective alternative for the initial site assessment and the role of LRGS in the subsequent remediation work. It
includes:
1 identification and selection of a field instrumentation/system for investigating the site.
2 details of the TERRIERTM system, incorporating the SAM935 Low Resolution Gamma Spectrometer (LRGS) with the
capability of real time identification of nuclides.
3 use of the TERRIERTM for a non-intrusive survey of the site, with rapid transformation of field data into informative plots
useful for remediation planning.
4 use of the TERRIERTM during remediation work, including assay of arisings.
5 benefits and limitations of using LRGS to support remediation of alpha contamination.
6 application of the instrumentation/system to other radiological investigations.
3) SAFE MANAGEMENT OF RADIOACTIVE MATERIALS FOUND IN PUBLIC LOCATIONS – 16032
Andrew Lewcock, Safeguard <strong>International</strong> Solutions Ltd. (UK);
Colette Grundy, Catherine Shaw, Environment Agency (UK)
In January 2006 the Environment Agency for England and Wales requested assistance in preparing a project to plan, collect
and safely dispose of radium painted aluminium aircraft hatches, discovered in 3 separate business premises in the UK. <strong>The</strong>se
World-War Two aircraft hatches had been marked with radium “luminous” paint, to guide crew in the dark to the escape exits if
they needed to bale out. <strong>The</strong> hatches had been stored since the early 1960s in one location, with some of the inventory being moved
two other locations in 2003/2004. <strong>The</strong> North West Region of the Environment Agency appointed a consortium of Enviros, Safeguard
<strong>International</strong> and Aurora Health Physics to undertake the work, and they funded it from the sealed sources disposal budget.
<strong>The</strong> paper will set out how the project was complicated by an assortment of “real world” problems; preliminary estimates of
both the activity per hatch and the number of hatches established the potential for a significant quantity of radium to be disposed
of safely. <strong>The</strong> total number of hatches was not known for sure at the start of the work. Access to retrieve the majority of the frames
was hazardous due to the poor structural condition of the building roof. Other difficulties included constrained access under a railway
line, and bird-related biohazards. <strong>The</strong> sites involved in the collections were not intended to house radioactive materials, so
physical security was another important issue. Some of the hatches were known to be in poor condition, with a very high probability
of radium contamination being spread to the surrounding areas. <strong>The</strong> hatches had to be removed from the sites before the full
extent of contamination of other materials could be established.
4) AN INTEGRATED SYSTEM FOR CONDUCTING RADIOLOGICAL SURVEYS
OF CONTAMINATED SITES - 16312
Charles Waggoner, Donna Rogers, Jay McCown, Mississippi State University (USA)
This paper describes an integrated detection system has been developed to conduct radiological surveys of sites suspected of
contamination of materials such as depleted uranium. This system utilizes cerium activated lanthanum bromide and thallium activated
sodium iodide gamma detectors and can be easily adapted to include units for detecting neutrons. <strong>The</strong> detection system
includes software controlling the collection of radiological spectra and GPS data. Two different platforms are described for conducting
surveys, a modified zero turn radius (ZTR) mower and a three-wheeled cart that is manually pushed.
<strong>The</strong> detection system software controlling data collection has components that facilitate completing a gridless survey on user
specified spacings. Another package confirms that all data quality activities (calibrations, etc.) are conducted prior to beginning the
survey and also reviews data to identify areas that have been missed of for which data quality falls below user designated parameters.
Advanced digital signal processing algorithms are used to enhance the interpretation of spectra for conducting background subtractions
and for mapping. Data from radiation detection and GPS antennae are merged and made compatible with mapping using
Geosoft Oasis montaj software.
A summary of system performance during field-testing is included in the paper. This includes survey rate, detection limits, duty
cycle, supporting ancillary equipment/material, and manpower requirements. <strong>The</strong> rate of false positives and false negatives is discussed
with the benefits of surveys conducted using synergetic detection systems such as electromagnetic induction imaging
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