manipulation 1945-2020 Part
The grand manipulation 1945-2020
In 1896 Henri Becquerel discovered spontaneous radioactivity when he opened a drawer. He had wrapped photographic plates in black paper so that sunlight could not reach them. He then placed the crystals of uranium salt on top of the wrapped plates, and put the whole setup away. When he later developed the plates, he saw a clear outline of the crystals. Thus he concluded that uranium salts emitted radiation without any stimulation from sunlight. Becquerel was not the first to make the same accidental discovery. Forty years earlier Abel Niece de Saint Victor, like Becquerel a photographer, did the same thing and observed the same phenomenon.
There are many types of radiation;
Radioactive Decay is exhibited by radioactive atoms. This includes the emission of Electro Magnetic Radiation (EMR). There are two classes of EMR; Ionizing and Non-ionizing radiation. EMR is photons of varying frequencies. EMR by photons is classified (short to long wavelength/frequency) as Radio Waves; Micro Waves; Infra Red; Visible Light; Ultra Violet; X-Rays; Gamma Rays. Photons have no mass at all only energy.
Ionizing radiation has enough energy to ionize atoms, in other words to remove one or more of an atom's electrons. Ionizing radiation has the ability to cause chemical reactions and damage living cells beyond that resulting from simple heating, and can be a health hazard. These are photons of high energy/frequency referred to as X-Rays and Gamma Rays.
Non-ionizing radiation does not individually have enough energy to ionize atoms or molecules or break chemical bonds. The effects of non-ionizing radiations on chemical systems and living tissue are caused primarily by heating effects from the combined energy transfer of many photons. This is EMR of visible or lower frequencies (i.e., visible light, infrared, microwaves, and radio waves).
In addition to EMR by photons, also emitted can be Alpha Particles; Beta Particles; Nuclear Fission products.
Alpha Decay is a type of radioactive decay in which an atomic nucleus emits an Alpha Particle (actually a helium nucleus) and thereby transmutates or 'decays' into a different atomic nucleus, (chemical element) with a mass number that is reduced by four and an atomic number that is reduced by two.
Beta Decay consists of two types; Beta Minus and Beta Plus:
Beta minus - A neutron is converted to a proton plus an electron is created. Nuclear transmutation with increase in Atomic Number by 1 into different element,
Beta plus - A proton is converted to a neutron plus a positron is emitted. Nuclear transmutation with decrease in Atomic Number by 1,
Transmutation means that the source element becomes a different element e.g. Uranium into Thorium.
People safely absorb small levels of radiation every day. Plants, rocks and even human bodies give off radiation. But how much radiation is normal?
In an attempt to confuse us, the scientific community insists on using different measurement units. You will find this ruse in many areas of science.
One of the most common units to measure the amount of radiation absorbed by an object is a gray. One gray represents the amount of radiation present when one Joule of energy is absorbed by one kilogram of material. A gray represents a large amount of radiation, much greater than a person would typically absorb. For example, 10 to 20 gray is usually lethal for humans. Therefore fractions of gray, such as centigray (0.01 gray), milligray (0.001 gray) and so forth are used. Rad is an obsolete unit proportional to gray. One gray is 100 rad, which makes one rad equal to one centigray.
The amount of radiation a body absorbs is not always equivalent to the amount of damage this radiation will cause. Additional units, such as radiation dose equivalent units, are used to describe radiation as relevant to the damage it can cause.
Sieverts measure the amount of energy emitted by the radiation per a given amount of tissue mass. This is one of the most commonly used units when discussing the harmful effects of the radiation on people and animals. For example, a generally fatal dose for people is about 4 sieverts (Sv). A person may still be saved if treated quickly, but a dose of 8 Sv is lethal. Generally people absorb much smaller doses of radiation, therefore millisieverts and microsieverts are used. 1 millisievert is 0.001 Sv, and 1 microsievert is 0.000001 Sv.
The average person safely absorbs about 3.65 millisieverts (or 0.00365 sieverts) of radiation annually, through simple activities like living in a brick or concrete building (70 microsieverts a year) or sleeping next to another person (0.05 microsieverts). A person living within 50 miles of a nuclear power plant absorbs 0.09 microsieverts of radiation per year, which is less than the amount absorbed by eating a banana which surprisingly is also radioactive.
Banana equivalent dose (BED) units are used to measure the amount of radiation that the body absorbs after eating one banana. A banana equivalent dose can also be expressed in sieverts, it is equal to 0.1 microsieverts. Bananas are used because they contain potassium-40, a radioactive isotope that naturally occurs in some foods. Some examples in BED include: a dental X-ray is similar to eating 500 bananas; a mammogram is equivalent to eating 4000 bananas; and a fatal dose of radiation is like eating 80 million bananas. Quite a lot of bananas.
It is important to note that while the total absorption of radiation will result in biological damage, the extent of this damage is highly dependent on the duration of time, over which this absorption occurs. For example, a dose of 1,000 rad or 10 Gy is fatal if absorbed within several hours, but it may not even cause acute radiation sickness (ARS) if spread out over a longer duration of time.
Radiation levels are higher at higher altitudes because cosmic radiation causes greater exposure and absorption than terrestrial radiation. Compared to the 0.06 microsieverts per hour on the ground it increases about 100 times to 6 microsieverts per hour at cruising altitudes.
A commercial pilot may spend about 80 hours per month or 960 hours per year in flight. This gives a total exposure of 5760 microsieverts or 5.76 millisieverts per year. This is a little less than a chest CT scan (the scan is 7 millisieverts). It is one tenth of the maximum allowed yearly dose that radiation workers in the USA can be exposed to.
You may see the unit of rad in use. 100 rad = 1 Gray (Gy).
The Earth's atmosphere protects us from the harmful effects of radiation coming from space and from the sun. So outside the Earth's atmosphere how much could we expect to absorb and how would it affect us?
Q1 What is the allowable dosage?
A1 70rads is considered an unsafe dose. Lethal dose (LD) The dose of radiation expected to cause death to 50 percent of an exposed population within 30 days (LD 50/30). Typically, the LD 50/30 is in the range from 4 to 5 sieverts received over a very short period.
Q2 How many sieverts would a person get if not shielded by Earth's atmosphere?
A2 Cosmic radiation - Cosmic rays are atom fragments that rain down on the Earth from outside of the solar system. They blaze at the speed of light and have been blamed for electronics problems in satellites and other machinery. We know today that galactic cosmic rays are atom fragments such as protons (positively charged particles), electrons (negatively charged particles) and atomic nuclei. For people outside the protection of Earth's magnetic field, space radiation becomes a serious hazard. An instrument aboard the Curiosity Mars rover during its 253-day cruise to Mars revealed that the radiation doze received by a space traveller on even the shortest Earth-Mars round trip would be about 0.66 sievert. This amount is like receiving a whole-body CT scan every five or six days.
Meanwhile back on Earth, the largest natural contributor to public radiation dose is Radon, a naturally occurring radioactive gas found in soil and rock. If the gas is inhaled some of the Radon particles may attach to the inner lining of the lung. These particles continue to decay, emitting Alpha Particles, which can damage cells in the lung tissue.
Otherwise Acute Radiation Sickness (ARS) can be caused by exposure to penetrating radiation e.g. X-Rays, Gamma-Rays, Alpha Particles (Helium nucleus), Beta Particles (Electrons), Neutrons. Note that ionizing radiation can also be used for health benefits.
The 4 classic ARS syndromes are:
a) Bone Marrow syndrome (Hematopoietic syndrome) - The full syndrome will usually occur with a dose between 0.7 and 10 Gy (70-1000 rads) though mild symptoms may occur at lower doses. The primary cause of death is the destruction of bone marrow resulting in infection and haemorrhage.
b) Gastrointestinal (GI) syndrome - The full syndrome will usually occur with a dose greater than 10 Gy (1000 rads) though some symptoms may occur at lower doses. Survival is extremely unlikely. Destructive and irreparable changes in the GI tract and bone marrow usually cause infection, dehydration and electrolytic imbalance. Death usually occurs within 2 weeks.
c) Cardiovascular (CV)/ Central Nervous System (CNS) syndrome - The full syndrome will usually occur with a dose greater than 50 Gy (5000 rads) though some symptoms may occur at lower doses. Death occurs within 3 days. It is due to the collapse of the circulatory system as well as increased pressure in the cranial vault as the result of increased fluid content caused by edema, vasculitis and meningitis.
d) Cutaneous Radiation Syndrome (CRS) - Skin damage occurs due to acute exposure to beta radiation or x-rays. Healing occurs by regenerative means. Very large skin doses can cause permanent hair loss, damaged sebaceous and sweat glands, atrophy, fibrosis, changed skin pigmentation, ulceration or necrosis of the exposed tissue.
It seems no such ARS syndromes or damages were noted by doctors at Hiroshima and Nagasaki 1945.
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