Fase III — Gestión predictiva de riesgos ESTADOS

I.L.F. RAY, T. WISS, H. THIELE

European Commission, Joint Research Centre, Institute for Transuranium Elements,

Karlsruhe

Abstract

Since 1994, the Institute for Transuranium Elements has played the leading role in Europe in the development of nuclear forensic science. The Institute has been involved in the investigation of all of the major cases of illicit trafficking involving nuclear and nuclear related materials in Europe, from the first major incident at Munich airport up to the present time. Three examples illustrate different types of cases. The first is an accidental release of nuclear material: on the seabed and beaches in the vicinity of the Dounreay nuclear establishment in Scotland. The second case involves an exercise carried out in co-operation with the German Federal Police (Bundeskriminalamt) in which a “seized” sample of high enriched uranium was delivered to the laboratory for examination to determine its composition, origin and intended use. The third case addresses a removal of nuclear material with deliberate criminal intent. As part of an actual police investigation, the Institute examined stolen material along with personal items of clothing from the people involved.

1. INTRODUCTION

Since 1994, the Institute for Transuranium Elements has played the leading role in Europe in the development of nuclear forensic science. This new discipline developed by necessity following the breakup of the former Soviet Union and Eastern Bloc countries in 1989, which resulted in the emergence of a new form of smuggling — that of nuclear materials. The Institute has been involved in the investigation of all of the major cases of illicit trafficking involving nuclear and nuclear related materials in Europe since the first major incident, at Munich airport, in 1994.

The Munich airport incident gave birth to nuclear forensic science and to the concept of the nuclear fingerprint as a characteristic of nuclear materials.

Examples given here illustrate different types of cases: accidental release of nuclear material into the environment, an exercise carried out in co- operation with the German Federal Police (Bundeskriminalamt), and the removal of nuclear material from a reprocessing plant in Karlsruhe, Germany,

with deliberate criminal intent. This last case is the closest approach, so far, to an act of nuclear terrorism.

2. DOUNREAY RADIOACTIVE PARTICLES

Over a period of about 10 years, highly radioactive particles — “hotspots” — about 1 mm in size were found on the seabed, and occasionally on beaches, in the vicinity of the Dounreay nuclear establishment in Scotland, following accidental discharge some years ago.

Two particles, one from the seabed and one from the foreshore, were analysed at the Institute to establish composition, origin and age. An examina- tion was made using a Philips XL40 scanning electron microscope (SEM) that has the microscope column and pumping system separated from the control console and is mounted inside a closed glovebox for handling contaminated samples. The instrument is equipped with energy dispersive X ray (EDX) analysis facilities. Figure 1 shows a micrograph of a particle recovered from the foreshore which was about 2 mm in length. The particles were found to be encrusted with a layer that prevented dissolution in the sea water.

The particles were shown by EDX analysis to consist of UAl₃islands in an aluminium matrix, identifying their origin as the Dounreay materials test reactor. Figure 2 is an elemental mapping of a small area of a cross-sectioned particle from the seabed, showing typical distribution of the fuel in the matrix. Age determination using caesium isotopic ratios showed that the material had been last processed about 30 years before.

3. ITWG URANIUM ROUND ROBIN TEST

The Institute was a participant in a Uranium Round Robin Test organized by the International Technical Working Group (ITWG) on nuclear smuggling. In this exercise a “seized” sample of high enriched uranium was delivered to each laboratory for examination, to determine its composition, origin and intended use.

The exercise, treated as a real case, was carried out in co-operation with specialist officers from the Bundeskriminalamt (BKA) who examined the container as delivered for a possible conventional “booby trap” explosive device. Figure 3 illustrates the X ray examination of the container in which the sample was delivered. The officers were present in the laboratories during opening and examination of the material to advise the scientists on the preser- vation of conventional forensic information. Much useful information on opti- mizing collaboration between police and nuclear scientists resulted from this exercise.

The containers and various items therein were examined for conventional forensic evidence, and a fingerprint was imaged on a contaminated brass container by cyanoacrylate vaporization under glovebox conditions.

Examination and reporting on the sample followed a scheme prescribed by ITWG: after 24 h, 1 week, and, finally, at 2 months. The sample was identified as reprocessed U₃O₈with an enrichment of 89.89 235_{U (wt%), aged 22.4 ± 1.2 years.}

20 20 µµmm

FIG. 2. An EDX elemental distribution map recorded of the cross-section of a particle recovered from the seabed showing UAl3islands (green) in an aluminium matrix (red).

Three distinct morphological components were identified in the powder by SEM and by transmission electron microscopy (TEM); the isotopic compo- sitions of all three were identical. The material was found to be very pure.

4. NUCLEAR AND RADIOACTIVE MATERIAL REMOVED FROM

A NUCLEAR INSTALLATION WITH CRIMINAL INTENT

A worker, involved in dismantling a nuclear installation in Karlsruhe, removed items contaminated with nuclear materials and took them home, resulting in heavy contamination of his apartment and high body incorporation for him and his partner.

The Institute examined the stolen material that was recovered by the police, along with items of clothing from the people involved.

One of the recovered items was a broken plastic tube that had held a liquid, the dried remains of which contained 137_{Cs, plutonium and americium.} Although of plastic, the tube was shown by SEM to have undergone brittle fracture, suggesting that, at some point, it had been stored at a low temperature (Fig. 4). Analysis of a second item, a cloth used for decontamination at the plant, revealed particles containing plutonium and uranium.

FIG. 3. X ray image of the container in which the samples were received, taken by specialists from the BKA to check for a conventional explosive device.

FIG. 4. Scanning electron micrographs indicating a brittle-type fracture of the plastic tube used for transport of stolen radioactive material, suggesting that the tube had been stored at a low temperature at some stage.

PROBLEMS OF ILLICIT TRAFFICKING OF