Hot particle

Last updated
Hot particles irradiating from inside subject Hotspecsinlung.jpg
Hot particles irradiating from inside subject

A hot particle is a microscopic piece of radioactive material that can become lodged in living tissue and deliver a concentrated dose of radiation to a small area. A generally accepted theory proposes that hot particles within the body are vastly more dangerous than external emitters delivering the same dose of radiation in a diffused manner. [1] [2] [3] [4] Other researchers claim that there is little or no difference in risk between internal and external emitters, maintaining that individuals will likely continue to accumulate radiation dose from internal sources even after being removed from the original hazard and properly decontaminated, regardless of the relative danger from an internally sourced radiation dose compared to an equivalent externally sourced radiation dose.

Contents

The theory has gained most prominence in debates over the health effects of nuclear accidents, dirty bombs or fallout from nuclear weapons, all of which can spread hot particles through the environment. The current ICRP risk model for radiation exposure is derived from studies of victims of external radiation, and detractors claim it does not adequately estimate the risk of hot particles.

Attributes

Hot particles contained in far-traveled nuclear fallout range in size from 10 nanometers to 20 micrometers, whereas those present in local fallout may be much larger (100 micrometers to several millimeters). Hot particles can be identified by a Geiger counter, or by autoradiography, i.e., fogging X-Ray film. Their age and origin can be determined by their isotopic signature.

Due to their small size, hot particles may be swallowed, inhaled or enter the body by other means. Once lodged in the body, cells very near the hot particle may absorb much of its radiation, and be bombarded in a very sustained and concentrated fashion. By contrast, an external radioactive source delivering the same total amount of radiation over the whole body would give a relatively minute dose to any one cell. [5] [6] [7] [8]

Estimating health risk

The Committee Examining Radiation Risks of Internal Emitters (CERRIE), established by the UK Government, carried out a 3-year-long independent expert review into the health risks of internal emitters (i.e., hot particles) and published its findings in 2003. The study failed to reach consensus, but the conclusion of the majority of its members was that the current ICRP risk model, despite being largely derived from studies of survivors of external radiation, adequately estimates the risk of hot particles, and that any differences between internal and external radiation are adequately accommodated by the established parameters in physiological models (relative biological effectiveness, kinetic factors); i.e., that internal radiation does not seem to be significantly more dangerous than an equal amount of externally delivered radiation. However, they noted significant levels of uncertainty regarding dose estimates for internal emitters, especially regarding less common radionuclides such as 239Pu and 241Am, and even more common ones such as 90Sr. [9] Two of the twelve members disagreed with the overall findings, notably Christopher Busby who advocates controversial physico-biological mechanisms such as Second Event Theory and Photoelectric Effect Theory, by which he believes the danger of ingested particles could be greatly enhanced.

Another study largely corroborates the CERRIE findings, though emphasizing the paucity of useful data, substantial uncertainties over accuracy, and the existence of evidence for at least some modest "enhanced cell transformation for hot-particle exposures". [10]

Origin

Hot particles released into the environment may originate in nuclear reactors or nuclear explosions. The Chernobyl disaster was a major source of hot particles, as the core of the reactor was breached, but they have also been released into the environment through illegal dumping of low-level waste at Dounreay. [11] They are also a component of the black rain or other nuclear fallout resulting from detonations of a nuclear weapon, including the more than 2000 nuclear weapons tests in the mid-20th century. [12] Nonradioactive substances can be turned radioactive primarily through neutron activation, though other reactions are also possibilities; this induced radioactivity can be dispersed in hot particles.

Cold War nuclear tests included safety trials in which fissile material was not detonated, but was sometimes dispersed, including plutonium vapor, plutonium aerosols of various sizes, plutonium oxide particulates, plutonium-coated particles, and sizeable lumps of plutonium-contaminated structural material. [12]

Accidents involving satellites and other devices are another source. The crash of the Kosmos 954 satellite released hot particles from its onboard BES-5 nuclear powerplant. [12]

Accidents during transportation of nuclear weapons or nuclear waste are another potential source. A Boeing B-52 Stratofortress nuclear-armed bomber crashed in the area of the northwest Greenland town of Thule (since renamed to Qaanaaq), [13] releasing hot particles. [12]

Common failure of nuclear fuel may result in fuel fleas, which can be found in some facilities that process spent nuclear fuel.

Related Research Articles

Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.

<span class="mw-page-title-main">Sievert</span> SI unit of equivalent dose of ionizing radiation

The sievert is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing radiation, which is defined as the probability of causing radiation-induced cancer and genetic damage. The sievert is important in dosimetry and radiation protection. It is named after Rolf Maximilian Sievert, a Swedish medical physicist renowned for work on radiation dose measurement and research into the biological effects of radiation.

Ionizing radiation, including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum.

Radiation dosimetry in the fields of health physics and radiation protection is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both internally, due to ingested or inhaled radioactive substances, or externally due to irradiation by sources of radiation.

Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination.

Equivalent dose is a dose quantity H representing the stochastic health effects of low levels of ionizing radiation on the human body which represents the probability of radiation-induced cancer and genetic damage. It is derived from the physical quantity absorbed dose, but also takes into account the biological effectiveness of the radiation, which is dependent on the radiation type and energy. In the SI system of units, the unit of measure is the sievert (Sv).

<span class="mw-page-title-main">Health physics</span>

Health physics, also referred to as the science of radiation protection, is the profession devoted to protecting people and their environment from potential radiation hazards, while making it possible to enjoy the beneficial uses of radiation. Health physicists normally require a four-year bachelor’s degree and qualifying experience that demonstrates a professional knowledge of the theory and application of radiation protection principles and closely related sciences. Health physicists principally work at facilities where radionuclides or other sources of ionizing radiation are used or produced; these include research, industry, education, medical facilities, nuclear power, military, environmental protection, enforcement of government regulations, and decontamination and decommissioning—the combination of education and experience for health physicists depends on the specific field in which the health physicist is engaged.

<span class="mw-page-title-main">Radioactive contamination</span> Undesirable radioactive elements on surfaces or in gases, liquids, or solids

Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases, where their presence is unintended or undesirable.

The International Commission on Radiological Protection (ICRP) is an independent, international, non-governmental organization, with the mission to protect people, animals, and the environment from the harmful effects of ionising radiation. Its recommendations form the basis of radiological protection policy, regulations, guidelines and practice worldwide.

Radiobiology is a field of clinical and basic medical sciences that involves the study of the effects of ionizing radiation on living things, in particular health effects of radiation. Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure. High doses can cause visually dramatic radiation burns, and/or rapid fatality through acute radiation syndrome. Controlled doses are used for medical imaging and radiotherapy.

In radiobiology, the relative biological effectiveness is the ratio of biological effectiveness of one type of ionizing radiation relative to another, given the same amount of absorbed energy. The RBE is an empirical value that varies depending on the type of ionizing radiation, the energies involved, the biological effects being considered such as cell death, and the oxygen tension of the tissues or so-called oxygen effect.

Committed dose equivalent and Committed effective dose equivalent are dose quantities used in the United States system of radiological protection for irradiation due to an internal source.

Internal dosimetry is the science and art of internal ionising radiation dose assessment due to radionuclides incorporated inside the human body.

<span class="mw-page-title-main">Christopher Busby</span> British scientist

Christopher Busby is a British scientist primarily studying the health effects of internal ionising radiation. Busby is a director of Green Audit Limited, a private company, and scientific advisor to the Low Level Radiation Campaign (LLRC).

<i>Chernobyl: Consequences of the Catastrophe for People and the Environment</i>

Chernobyl: Consequences of the Catastrophe for People and the Environment is a translation of a 2007 Russian publication by Alexey V. Yablokov, Vassily B. Nesterenko, and Alexey V. Nesterenko, edited by Janette D. Sherman-Nevinger, and originally published by the New York Academy of Sciences in 2009 in their Annals of the New York Academy of Sciences series.

Effective dose is a dose quantity in the International Commission on Radiological Protection (ICRP) system of radiological protection.

The committed dose in radiological protection is a measure of the stochastic health risk due to an intake of radioactive material into the human body. Stochastic in this context is defined as the probability of cancer induction and genetic damage, due to low levels of radiation. The SI unit of measure is the sievert.

Ian Fairlie is a U.K. based Canadian consultant on radiation in the environment and former member of the three person secretariat to Britain’s Committee Examining the Radiation Risks of Internal Emitters (CERRIE). He is a radiation biologist who has focused on the radiological hazards of nuclear fuel and he has studied radioactive releases at nuclear facilities since before the Chernobyl accident in 1986.

Richard JohnPentreath is a British marine scientist who made major contributions to radioecology, particularly with regard to alpha-emitting nuclides in the marine environment. He went on to broaden the international system of radiological protection to include animals and plants with respect to different exposure situations, as well as protection of the animal as patient in veterinary medicine. He also played a major role in the success of the National Rivers Authority and its subsequent merging with other bodies to form the Environment Agency.

Sergey Anatolyevich Romanov, born 20 September 1958, is a Russian scientist, internal dosimetry and radiation protection specialist, PhD in biology (2003). He currently serves as Director in the Southern Urals Biophysics Institute, having been appointed in 1997. He is the author and coauthor of more than 150 research papers.

References

  1. ↑ https://www.nrc.gov/reading-rm/basic-ref/students/science-101/what-are-different-types-of-radiation.html
  2. ↑ "Radiation in Everyday Life". 21 November 2014.
  3. ↑ Peräjärvi, Kari; Ihantola, Sakari; Toivonen, Harri; Sand, Johan; Toivonen, Juha (2015). "In-field detection and analysis of α radiation" (PDF). International Atomic Energy Agency.
  4. ↑ Scott, Bobby R. (20 April 2007). "Health risk evaluations for ingestion exposure of humans to polonium-210". Dose-Response. 5 (2): 94–122. doi:10.2203/dose-response.06-013.Scott. PMC   2477690 . PMID   18648599.
  5. ↑ Charles, M W; Harrison, J D (1 September 2007). "Hot particle dosimetry and radiobiology—past and present". Journal of Radiological Protection. 27 (3A): A97–A109. Bibcode:2007JRP....27...97C. doi:10.1088/0952-4746/27/3A/S11. PMID   17768323. S2CID   36276000.
  6. ↑ Charles, M.W. (1 November 1991). "The Hot Particle Problem". Radiation Protection Dosimetry. 39 (1–3): 39–47. doi:10.1093/rpd/39.1-3.39.
  7. ↑ Health Effects of Alpha-emitting Particles in the Respiratory Tract: Report of Ad Hoc Committee on 'Hot Particles' of the Advisory Committee on the Biological Effects of Ionizing Radiations. U.S. Environmental Protection Agency, Office of Radiation Programs. 1976.[ page needed ]
  8. ↑ Baum, J. W.; Carsten, A. L.; Kaurin, D. G. L.; Schaefer, C. W. (June 1996). Acute skin lesions due to localized 'hot particle' radiation exposures. 9. International Congress on Radiation Protection and General Assembly of the International Radiation Protection Association (Irpa), Vienna (Austria), 14-19 Apr 1996. OSTI   248698.
  9. ↑ Goodhead, Dudley; Bramhall, Richard; Busby, Chris; Cox, Roger; Darby, Sarah; Day, Philip; Harrison, John; Muirhead, Colin; Roche, Peter; Simmons, Jack; Wakeford, Richard; Wright, Eric (2004). Report of the Committee Examining Radiation Risks of Internal Emitters: (CERRIE) (PDF). National Radiological Protection Board. ISBN   978-0-85951-545-0.[ page needed ]
  10. ↑ Charles, M W; A J Mill; P J Darley (March 2003). "Carcinogenic risk of hot-particle exposures". Journal of Radiological Protection. 23 (1): 5–28. doi:10.1088/0952-4746/23/1/301. ISSN   0952-4746. PMID   12729416. S2CID   250742652.
  11. ↑ Hot particles at Dounreay Nuclear Monitor
  12. 1 2 3 4 Danesi, Pier Roberto (19 May 2014). "Hot Particles & the Coldwar". IAEA Bulletin. 40 (4): 43–46.
  13. ↑ "FINAL REPORT ISSUED ON 1968 THULE CRASH". The New York Times. 1 March 1970.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.