China
Africa
Explore chapters and articles related to this topic
Nuclear Logs
Published in W. Scott Keys, in Environmental Investigations, 2017
The statistical nature of radioactive decay must be considered when collecting or interpreting nuclear logs. Half-life is the amount of time required for one half the atoms in a radioactive source to decay to a lower energy state. The half-life of different radioisotopes has been accurately measured, varying from fractions of a second to millions of years. In contrast, it is impossible to predict how many atoms will decay or gamma photons will be emitted within the short periods of time, in the range of seconds, that commonly are used for logging measurements. Photon emission follows a Poisson distribution; the standard deviation is equal to the square root of the number of disintegrations recorded. Thus the accuracy of measurement is greater at high count rates and for long measuring periods.
Environmental Health Emergencies, Disasters, and Terrorism
Published in Herman Koren, Best Practices for Environmental Health, 2017
Radiological material including that which is used for nuclear weapons is available in several places in the world. There is an ever present concern about the material being used by terrorists. Terrorists might consider attacking a nuclear power plant or the spent fuel pools which contain a large amount of radioactive material. They may try to purchase existing nuclear weapons or create an improvised nuclear device. A dirty bomb (radiological dispersal device) is a combination of conventional explosives with radioactive material. Whereas the explosion of a nuclear bomb or nuclear weapon is far more powerful than that of a dirty bomb and could spread over large areas of land and effect innumerable people, the dirty bomb depending on the amount of explosives, type of radioactive material, how it is dispersed and local weather conditions could contaminate individuals and equipment but would be most effective in terrifying the community. Radioactive material can be found in hospitals, research facilities, industrial facilities, and construction sites. There is a risk of cancer to individuals who are contaminated by the radioactive sources. The level of potential disease for individuals depends on the amount and type of radiation involved in the exposure. (See endnote 77.)
X-Ray History
Published in Harry E. Martz, Clint M. Logan, Daniel J. Schneberk, Peter J. Shull, X-Ray Imaging, 2016
Harry E. Martz, Clint M. Logan, Daniel J. Schneberk, Peter J. Shull
Of the radiation incidents/accidents reported worldwide since 2000, radioisotopes were the radiation source in all but one case. The most common isotope involved in accidents is 77192Ir (Turai and Veress 2001). This isotope is used in both medical procedures and industrial inspection. We describe briefly three accidents involving 77192Ir because the similarities convey a useful lesson. Radioactive sources are usually in a sealed capsule. The capsule is attached to a cable, and the assembly is housed within a guide tube. The source capsule can be pulled via the cable into a shielded container when not in use or pushed through the guide tube into position for use.
Photon attenuation coefficients of different rock samples using MCNPX, Geant4 simulation codes and experimental results: a comparison study
Published in Radiation Effects and Defects in Solids, 2018
Shamsan S. Obaid, M. I. Sayyed, D. K. Gaikwad, H. O. Tekin, Y. Elmahroug, P. P. Pawar
Radioactive sources have been used by modern society for a variety of fundamental and technological applications in nuclear reactors, nuclear weapons, medicine, radiation therapy, X-rays and gamma ray scanners at airports and railway stations, agriculture, nuclear research, etc. It is well known that gamma rays are strongly penetrating ionizing radiation, hence they are hazardous for the human being, and thus the precautions must be taken by shielding these harmful radiations. The knowledge of appropriate physical properties of building materials to provide a suitable radiation protection is essential to reduce radiation hazard. The mass attenuation coefficient (μ/ρ), mean free path (MFP) and half-value layer (HVL) are basic required quantities to understand radiation shielding capability of different materials (1).