Mobile Units for Characterization of Contaminated Sites

Abstract

As part of an environmental, accidental or terroristic action remediation plan to be applied to areas affected by past activities, accidents or terroristic attacks, characterization of the site is a mandatory step. This activity will determine the extent of the contamination, contaminants’ distribution, etc. Traditionally, this activity involves the collection of different environmental samples and laboratory analysis of the relevant radio nuclides (and eventually other contaminants like heavy metals). When the results are available they are interpreted and then a decision is made. This process is normally very expensive and time consuming. In recent years many techniques have been made available for in-situ measurement that can provide reliable information on the contamination profile in radiological contaminated land. Such measurements tend to be less expensive, faster and with the aid of GPS/GIS systems decisions can be made on-site in real time. To overcome this situation we developed the DACM (Data Acquisition and Control Module) technology. Instruments based on this technology can be modified anytime by the user without special knowledge and the claiming of the manufacturer.

The DACM based offers a set of components which can be configured, parameterized and controlled with respect to the requirements on site. Typical components are signal inputs for sensors like Co₂, Methane, So₂.., control outputs for instance for pumps, magnetic valves but also complex functional blocks like spectrometers, GPS receiver, PID regulators etc. A complex sampling schedule can be created within few minutes by a graphical software interface.

One version of this system is the NucScout as a handy and robust 2^″ × 2^″(optional 3^″ × 3^″) NaI(TI) Nuclide Identifier and quantifier. With less than 2 kg including GPS and ZigBee wireless connection, if the device is operated in inaccessible or contaminated areas, he can be so calibrated by use in 1 m high from the soil, that he show direct the nuclide activity in Bq/kg. So you can get with a time resolution of 10 s and a speed of 1 m/s a local resolution of 10 m and you can detect a specific activity less than 200 Bq/kg soil activity on the surface.

The NaI(TI) detector is also used to analyze food and material probes regarding specific nuclides (e.g. Iodine, Caesium, Americium). By means of the gamma spectrum, the net activity of six user definable nuclides is automatically calculated.

A version with a aerosol sampling head with its spectroscopy filter and its silicon detector samples continuously and detects even small quantities of aerosol carried radioactivity. Both alpha and beta radiation are measured. The spectrometric analysis allows e.g. detecting Plutonium aerosols which cannot be detected by measuring gamma radiation.

Optionally, the DACM can be connected to a portable vacuum chamber with Ion-implanted Silicon detector up to 2,000 mm², to allow on-site analysis of mop tests and other samples under circumstances similar to those prevailing in a laboratory. The employed vacuum pumps can be connected to a 12 V source (car battery).

All detectors can be operated simultaneously. The concept of the system allows an easy handling and a standardized data basis.