G. Lindner

Chernobyl: an early report

An overview and assessment of the nuclear accident at Chernobyl is presented. The authors have assembled data from throughout Europe to estimate upper bounds for the possible radiation releases from the accident, the exposures these may produce in humans, and the health consequences that may follow. Measurements of radioactivity in air, fallout, and milk and other food are included. Doses from the accident are compared with those from other sources of radiation exposure and a comparison is made of the annual risk of cancer from this and other causes.

Biological Transfer and Sedimentation of Chernobyl Radionuclides in Lake Constance

Considering the input of Chernobyl radionuclides into Lake Constance on April 30, 1986, as the starting point of an unplanned radiotracer experiment, we followed the fate of five long-lived, gamma-emitting radionuclides (137Cs, 106Ru, 125Sb, 110mAg, and 144Ce) in order to obtain information about their scavenging and sedimentation properties, and their transfer into and within the food-web. In particular, we studied the uptake and excretion by fish of 137Cs. With respect to the transfer of 137Cs into fish, we also performed comparative investigations in the Schreckensee, a small shallow lake in the vicinity of Lake Constance.

Localization of implanted radioactive probes by channeling of β−, β+ and conversion electrons

Abstract The ISOLDE facility at CERN has been utilized for ion implantations of radioactive In isotopes into Cu single crystals for impurity lattice-location studies by means of the channeling effects of emitted charged particles. Conversion electrons with energies around 0.2MeV (112In, 114In), electrons from β−-decays with energies up to 2 MeV (114In, 119In) and positrons (112In) were employed for the channeling measurements. These experiments demonstrate the possibility of combining channeling and Mossbauer effect measurements using 119In under identical experimental conditions.

Channeling of conversion electrons from radioactive impurities for analysis of atomic structures in solids

Abstract The channeling effect of conversion electrons emitted from implanted radioactive 111 In impurities was investigated in Cu, Mo and Au and compared with calculations based on the dynamical theory of electron diffraction. From these calculations electron channeling turns out to be most sensitive to small displacements of impurities from substitutional sites as happens in the case of vacancy trapping. The combined application of perturbed γγ-angular correlation (PAC) and electron channeling employing 111 In for the analysis of vacancy trapping configurations in Cu is demonstrated in an annealing experiment in recovery stage III after H + irradiation. A fraction of about 20% of probe atoms at tetrahedral interstitial sites and indications for small displacements of about 0.2 A of substitutional impurities due to monovacancy trapping were found at an annealing temperature of 250 K.

Probing of lattice defects by radioactive atoms

Abstract The production of alloys via implantation is of great interest. Using the perturbed γγ angular correlation technique we have studied Cu implanted with In atoms (

Lattice Location of Nuclear Probes by Electron and Positron Channeling

The angular dependence of the emission yields of electrons and positrons emitted from radioactive probes implanted into single crystals was first investigated by Uggerhoj.1 The channeling effect of electrons, emitted from substantial lattice sites, is responsible for enhanced emission yields in the directions of crystal axes or planes. Positrons, on the other hand, show pronounced channeling peaks, if emitted from interstitial sites and blocking dips, if emitted from substantial lattice sites as shown for a ‹110› direction in a 112m In implanted Mo crystal (Fig. 1). In an early paper2 Uggerhoj and Andersen suggested that this effect may be used as a method for the localization of foreign atoms in single crystals. From the emission yields observed for different low index crystal directions, the lattice site occupancy of the emitter atoms can be determined.

The Accident at Chernobyl: A Report on Risk Management at a Local Hot Spot in West Germany

Local fallout in the days following the accident at Chernobyl reached levels 30 to 40 times natural background at locations as far as 1500 km from the accident. In the absence of coordinated responses at the state and national levels, spontaneously generated local risk management efforts were undertaken in many places. We describe here our own local risk management activities in a locally hot region of southern West Germany. Based on the achievement of high credibility with the local population and the institution of effective protective action in the food chain, we argue that in future radiological disasters risk management should retain a strong decentralized component.

Combined PAC and electron-channeling studies of He-defect interaction in CU between 300 and 900 K

Abstract The interaction of He atoms with defects in ‘“In-implanted Cu single crystals was investigated by simultaneous perturbed γγ-angular correlation (PAC) and conversion-electron channeling measurements during annealing in the temperature range 300 to 900 K. Below 600 K different He-defect complexes were formed with large fractions of In probe atoms, which are increasing with annealing temperature. No significant displacements of substitutional In atoms occur, however, as concluded from the unchanged electron channeling effects. Above 700 K the channeling effects vanish completely, but a unique quadrupole interaction is observed in the PAC spectra for a large part (25-40%) of the probe atoms. It is proposed that He bubble growth is responsible for the vanishing of the channeling effects and that In atoms are attached to these bubbles on a unique, well-defined site.

Detection of vacancy clustering by combined PAC and lattice location measurements

The formation of impurity-vacancy agglomerates starting with the trapping of monovacancies was studied using a combination of three complementary techniques applied to the system InCu: Perturbed γγ-angular correlation, ion channeling and channeling of conversion electrons. This results in an almost complete picture of the first stage of vacancy agglomeration at In impurities in Cu.