Markus R. Zehringer

By Markus Zehringer

The contamination of our environment and of food with artificial radionuclides originates from several sources. First, nuclear powers spread contamination all over the Northern Hemisphere by carrying out more than 600 atmospheric bomb tests from 1945 to 1963. The peaceful use of nuclear fission brought several accidents in nuclear installations [nuclear power plant (NPP)]. This began in the late 1940s and ended recently with the NPP’s core meltings at Fukushima-Daiji in 2011. The catastrophe at the Chernobyl NPP in 1986 spread enormous fallout over most parts of Europe. Besides the artificial contamination, one has to mention the exposure to naturally occurring radionuclides from the uranium and thorium decay series. From 1980 on, the State Laboratory Basel-City began a monitoring programme of food. Special equipment for the analysis of α-, β-, and γ-emitting radionuclides had to be built. In 1986/1987, the laboratory had to manage thousands of samples according to the accident at Chernobyl. The Government estimated the dose of the mean Swiss population from the ingestion of contaminated food to be 1 to 2 mSv. Today, the contamination of food has lowered significantly. The Office of Public Health estimated the total ingested dose of about 0.3 to 0.4 mSv/year. The main contribution comes from potassium-40 (40K; 0.2 mSv/year) and from natural radionuclides of the uranium and thorium decay series. The remaining contamination from the bomb fallout is less than 0.1 mSv/year.

Part of the book: Radiation Effects in Materials

By Markus R. Zehringer

Gamma radiation consists of high‐energy photons and penetrates matter. This is an advantage for the detection of gamma rays, as gamma spectrometry does not need the elimination of the matrix. The disadvantage is the need of shielding to protect against this radiation. Gamma rays are everywhere: in the atmosphere; gamma nuclides are produced by radiation of the sun; in the Earth, the primordial radioactive nuclides thorium and uranium are sources for gamma and other radiation. The technical enrichment and use of radioisotopes led to the unscrupulously use of radioactive material and to the Cold War, with over 900 bomb tests from 1945 to 1990, combined with global fallout over the northern hemisphere. The friendly use of radiation in medicine and for the production of energy at nuclear power plants (NPPs) has caused further expositions with ionising radiation. This chapter describes in a practical manner the instrumentation for the detection of gamma radiation and some results of the use of these techniques in environmental and food investigations.

Part of the book: New Insights on Gamma Rays

By Markus R. Zehringer

After World War II, the use of artificially produced radionuclides in medicine began and led to great success in the fight against cancer and other diseases. However, the highly radioactive compounds had to be handled with great care to protect patients and hospital personnel from radiation. The survey of these radionuclides in the environment followed some years later. In Switzerland, double-tracked monitoring programs were started. On the emission side, hospitals and industries handling radiopharmaceuticals had to report their consummation of radionuclides yearly. A monitoring program of their waste waters and solid wastes was also started. On the immission side, the remaining radioactive wastes, which were released to the environment, had to be surveyed. Overall, only a few violations of the limits for radiopharmaceuticals were observed over the last 30 years in Switzerland. Nevertheless, the monitoring of radioactivity in the environment remains an important task as long as radionuclides are used in medicine.

Part of the book: Sewage

By Markus Zehringer

Alpha spectrometry is an indispensable technique in the radiology lab for the analysis of natural radionuclides. While the powerful ICP/MS is used more and more for the analysis of uranium and thorium, other radionuclides, such as 226Ra, are difficult to analyze with this technique due to their very high specific activities. The following chapter is introduced by a description of the problems, which may occur when working in the ultra-trace level. A description of the commonly used extraction and enrichment techniques for alpha nuclides and a short survey of the commonly applied detection techniques are given. The main application of alpha spectrometry in our laboratory is the monitoring of tap and mineral waters. Besides water, some specific food categories, such as fish, seafood, spices or healing earths, are monitored for their content of natural radionuclides.

Part of the book: Ionizing and Non-ionizing Radiation