I have lived my entire life in the nuclear age. Technically, we no longer label present day as the “nuclear age”, meaning we do not define the present by nuclear technologies, that have been replaced by other disruptive technologies, which strikes me as odd since the world is filled with thousands of nuclear weapons, obtain around 20% of our nation’s energy needs from nuclear reactors, pop culture sci-fi abound with references to nuclear, and it is present in almost every aspect of our lives from medicine to cooking the food we eat.
We made the transition from the nuclear age – to the jet age – to the space age – to the information age…and so on – while I happily attended school, married, raised children, and worked in the garden. So why do I know so very little about nuclear science? I did cut school a lot to go to the beach, but, I think there was an overwhelming abhorrence to the science through my formative years and unless one was pursuing a career as a nuclear scientist, one could generally dismiss the “Atomic Age”. Personally this was in part this was cultural, a fear of the immense power of the atom, but, in the end I have to take responsibility for my lazy attitude toward all things nuclear.
The lesser known, and peaceful applications of splitting the atom have proved of value in horticulture crops that include mutagenesis, combating pest and diseases, increasing crop production and improvement in the quality of the produce.
It appears I am not alone. Most of us are aware of the contributions of nuclear in the production of electricity. I work in power generation – well, not in the hydroelectric generation itself – I work as a horticulturist at the Skagit Hydroelectric Project, so I am surrounded by high voltage power production and the energy production culture. I grew up in the shadow of the Diablo Nuclear Power Plant and remember the Chernobyl disaster, but, I have given little thought to the non-power applications of this technology that has changed the quality of our daily lives during the last 20 to 30 years. The wider use of radioisotopes and radiation sources in research, industry, agriculture and medicine were the initial objectives promoted by the International Atomic Energy Agency, which came into existence in 1957. These lesser known, and peaceful applications of splitting the atom have proved of value in horticulture crops that include mutagenesis, combating pest and diseases, increasing crop production and improvement in the quality of the produce. As I pursued my education in horticulture, I kept bumping into the science. I would bump and run, so to speak, and only lately have I sought the discipline to dive in.
Radiation is naturally occuring and we are exposed to ionizing radiation from natural sources in two ways:
- Naturally occurring radioactive elements are in the soil and rock that is exposed to high-energy protons and atomic nuclei, cosmic rays, that originate from the sun, outside our solar system and from distant galaxies.
- Internal exposure from radioactive elements that we take into our bodies through water, food, and even the air we breathe. We also have radioactive elements in our blood and bones (Potassium 40, Carbon 14, Radium 226)
Additional exposure to radiation comes through sources such as dental and medical X-rays, and other consumer products such as luminized wrist watches, ionization smoke detectors, etc. We are also exposed to radioactive elements contained in fallout from nuclear explosives testing, and routine normal discharges from nuclear and coal power stations.
So radiation is part of the earth, it is in, around us, and even in the soil of my garden. I study soil, water, nutrients…but never paused to understand the role of nuclear science in horticulture and once I did, I found it everywhere – documentaries, conferences, and in books I read. So, if like me, you are also ready to have a ‘dose’ of this amazing world – I have a few basics to help decipher the lingo. Call this a Nuclear Science for Dummies (in the Garden!).
What is the radiation process
A plant part (seed, shoot, or rhizome) is intentionally irradiated to change or improve its characteristics. Only a fraction of the radiation energy is absorbed by the tissues of the plant depending on the amount of time exposed, its mass and composition. To compare the process to a common use we all understand – Irradiation gamma rays, commonly used for mutagen, requires a very low dose when compared to X-rays.
Brief history of atomic gardening
Long before the advent of genetic engineering and in the aftermath of World War II, the only way of creating new species without waiting generations and generations for selective breeding to take place was a process called atomic gardening. The initiative to develop alternative uses for peaceful applications for the atom included “Gamma Gardens”. Created in the United States, Europe, Japan, India and Russia, these gardens were initially designed with the aim of testing effects of radiation on plant life, but research gradually turned towards using radiation to introduce beneficial mutations that could give plants useful characteristics that included increased resilience to adverse weather, higher sugar content, or a faster growth rate. Part of President Eisenhower’s “Atoms for Peace”, regarded by some as propaganda, it also led to some creative peaceful applications of nuclear technology in the civilian world.
A trend in food cultivation used nuclear technology in an attempt to produce new varieties of plant life. Some of these applications resulted in advances the are still used today with profound impacts on our quality of life as advances in inexpensive reliable electricity, operations, lifesaving medical technology, or radioisotope thermal generators paving the way for deep space probes – some projects just didn’t catch on such as Project Plowshare, which which had the goal of using nuclear explosions for large excavation projects!
“To the making of these fateful decisions, the United States pledges before you, and therefore before the world, its determination to help solve the fearful atomic dilemma – to devote its entire heart and mind to finding the way by which the miraculous inventiveness of man shall not be dedicated to his death, but consecrated to his life.”Atoms for Peace Speech Address by Mr. Dwight D. Eisenhower, President of the United States of America, to the 470th Plenary Meeting of the United Nations General Assembly
Tuesday, 8 December 1953, 2:45 p.m.
Perhaps not visionary, Gamma Gardens and the Atomic Garden Societies found their way into popularity during the 1950 and 1960’s. Gamma gardens, built in the shape of a cartwheel over about five acres, were research gardens. They were surrounded by dyke to prevent the radiation spreading outside the garden, and at the hub of the wheel was the radioactive material, either Cobalt -60 or Caesium-137. Plants are exposed to the radiation for seven to eight months with varying degrees, and would accumulate mutations in their DNA. The process is still used in many areas, as the equipment is easier to set up and less expensive than equivalent gene-modification equipment. It also has the possible advantage that it introduces no new genes, only accelerates the natural shuffling process of the existing genome. Most of the gamma garden experiments resulted in the plants closest to the radioactive source usually dieing and the ones a bit further out – developing tumors and becoming misshapen. The plants furthest away, however, mutated and did produce new and usable plants. The Rio Star grapefruit, which accounts for 75% of Texas’ grapefruit crop, along with a strain of peppermint resistant to verticillium wilt, was developed in this manner and many are still in production today. NOTE: The resulting plants are NOT radioactive themselves.
Briton Muriel Howorth, a rather eccentric and lifelong atomic activist from the United Kingdom, worked in conjunction with a growing movement to bring atomic energy and experimentation into the lives of ordinary citizens. The creation of the Atomic Gardening Society in 1959, promoted the cultivation of gamma-irradiated seeds and distributed seeds to interested gardeners who were supposed to report back with the results. In 1960, Howorth published a book entitled “Atomic Gardening for the Layman” along a similar theme, but unfortunately the feedback on the seed propagation was sporadic and the enthusiasm faded.
Perhaps the most interesting part of the Atomic Gardening Era is the do-it-yourself aspect. The Atoms for Peace effort also permitted citizens to get radioactive sources; one such citizen was an oral surgeon from Tennessee named C.J. Speas, who irradiated seeds in his backyard and then sold them to home gardeners or to kids for science projects.
Today, we can no longer apply to receive radiation source and radiation plant breeding has been largely supplanted by gene editing.
Speas showing a group of high school students some of his irradiated seeds. Edible Geography
nuclear technology in horticulture
In a time when NON-GMO is on the label of almost every product and proliferates Social media – it is easy to be confused. Genetically modified commonly refers to the transfer of genes between organisms using a series of laboratory techniques for cloning genes, splicing DNA segments together, and inserting genes into cells. Nuclear technology uses radiation to improve the productivity of the entire food chain in a substantial manner.
A GMO, or genetically modified organism, is a plant, animal, microorganism or other organism whose genetic makeup has been modified in a laboratory using genetic engineering or transgenic technology. This creates combinations of plant, animal, bacterial and virus genes that do not occur in nature or through traditional crossbreeding methods.https://www.nongmoproject.org/gmo-facts/what-is-gmo/
The Food and Agriculture Organization of the United Nations lists examples of nuclear technology that improves food and agriculture, making the case that the International Atomic Energy Agency (IAEA) has been expanding knowledge and enhancing capacity in this area for over 50 years and the most innovative techniques for improving agricultural practices involve nuclear technology. Given the human population increases, pronounced in poor developing countries, climate change and its negative effects on crop growth, petroleum costs and its related impact on crop production, food safety issues, seasonal famine issues, soil, water resources and pest management – the security of food production is a priority for everyone worldwide.
in 1916, successful experiments verifying the effects of an ionizing radiation were performed but entomologists really didn’t become aware of that sterility in insects could be economically and easily achieved through ionizing radiations after 1950. Today sterile insect technique (SIT), which involves the breading and sexual sterilization of male insects that are released into pest infested areas, gradually suppresses and eliminates already established pests or prevents the introduction of invasive species – and is safer for the environment and human health than conventional pesticide (U.N.) and is commonly used for controlling insects associated with agricultural and horticultural crops. The control of insects with chemical pesticides can leave toxic residues in food and cause environmental problems that include pesticide resistance and water contamination.
WEU – Water Use Efficiency can be improved with the valuable nuclear and isotopic tools – Soil Moisture Neutron Probe – a sophisticated and accurate piece of equipment that measures the moisture content in soil. The stable isotopes of water are used for tracking and quantifying water flows within and beyond the plant rooting zone and this technique can show the potential for dividing evapotranspiration into soil evaporation and plant transpiration. The advantages of the probe are minimal soil disturbance, accurate data not influenced by soil type, temperature or pH, but, with the limitation of high cost and the need for a licensed operator, the neutron probes are usually only purchased by large organizations or consultants.
If 2020 left us with a message, it would be that we are always vulnerable. Sterilization has become a daily and common practice for every home, business and public area, and the health of our food supply chain has been impacted from field to consumer. In the light of recent challenges, concern about food production, processing, distribution are being considered. An ongoing solution is in the use of radiation for purpose of sterilization of produce. The appropriate amounts of radiation can produce sterilized products that can be stored without refrigeration and extend the shelf life, reducing the need for chemicals for preservation and pest control. Use can inhibit sprouting of tuber, bulb, and root vegetables, a disorder that deteriorates the quality and renders the product unfit for consumption. In post harvest handling and storage, large amounts of produce is lost to infestation, microbial attack, and other physical and biological damage. Yeasts, molds, and bacteria in addition to foodborne gastrointestinal pathogens such as E. coli and Salmonella can be controlled by ionization radiation technology.
The use of irradiation in the genetic control of spoilage organisms on strawberries has been an effective treatment and is used commercially in the United States. India has overcome quarantine barriers for export of mango, spices, onion, and garlic by radiating horticultural produce, and without radiation the quarantine would present a barrier for the export of fruit, vegetables, and flowers from around the world.
Controlling and preventing transboundary animal diseases such as the highly contagious Brucellosis, a disease that can be transmitted from animals to humans through unpasteurized milk or undercooked meat from infected animals.
Nuclear techniques help national authorities in over 50 countries to improve food safety by addressing the problem of harmful residues and contaminants in food products and to improve their traceability systems with stable isotope analysis. For example, scientific programmes in Pakistan, Angola and Mozambique now enable the testing for veterinary drug residues and contaminants in animal products. Already some 50 Pakistani food production and export institutions benefit from the new laboratory testing capabilities, which help ensure they meet international food standards and boost the country’s reputation in the international food trade. (U.N.)
basic physics terminology
Alpha decay – nucleus ejects an alpha particle decreasing mass and atomic number by 4 and 2
Alpha particle – also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways
Alpha radiation – consists of heavy, positively charged particles emitted by atoms of elements such as uranium and radium. Alpha radiation can be stopped completely by a sheet of paper or by the thin surface layer of our skin (epidermis). However, if alpha-emitting materials are taken into the body by breathing, eating, or drinking, they can expose internal tissues directly and may, therefore, cause biological damage
Atom – consist of a nucleus made of protons and neutrons orbited by electrons
Beta decay – nucleus emits an electron or positron and a type of neutrino.Protons can become neutrons and vice versa — elements are transmuted
Beta radiation consists of electrons. They are more penetrating than alpha particles and can pass through 1-2 centimetres of water. In general, a sheet of aluminum a few millimetres thick will stop beta radiation
Decay (radioactive) – The change of one radioactive nuclide into a different nuclide by the spontaneous emission of alpha, beta, or gamma rays, or by electron capture. The end product is a less energetic, more stable nucleus. Each decay process has a definite half-life
That property of a substance which is expressed by the ratio of its mass to its volume
Dose – A general term denoting the quantity of radiation or energy absorbed in a specific mass
Electromagnetic radiation – Radiation consisting of electric and magnetic waves that travel at the speed of light. Examples: light, radio waves, gamma rays, x-rays
Electron – a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids
Excited state – The state of an atom or nucleus when it possesses more than its normal energy. The excess energy is usually released eventually as a gamma ray
Fission – The splitting of a heavy nucleus into two roughly equal parts (which are nuclei of lighter elements), accompanied by the release of a relatively large amount of energy in the form of kinetic energy of the two parts and in the form of emission of neutrons and gamma rays
Gamma decay – Energy of an excited nucleus emitted as a gamma ray w/o transmutation
Gamma rays – electromagnetic radiation similar to X-rays, light, and radio waves. Gamma rays, depending on their energy, can pass right through the human body, but can be stopped by thick walls of concrete or lead.
Half-life – The time in which half the atoms of a particular radioactive nuclide disintegrate. The half-life is a characteristic property of each radioactive isotope
Ion – An atomic particle that is electrically charged, either negative or positive
Ionizing radiation – Radiation that is capable of producing ions either directly or indirectly
Irradiate – To expose to some form of radiation
Isomer – One of several nuclides with the same number of neutrons and protons capable of existing for a measurable time in different nuclear energy states
Isometric transition – A mode of radioactive decay where a nucleus goes from a higher to a lower energy state. The mass number and the atomic number are unchanged
Isotope – Isotopes of a given element have the same atomic number (same number of protons in their nuclei) but different atomic weights (different number of neutrons in their nuclei)
Neutrino – a neutral subatomic particle with a mass close to zero and half-integral spin, rarely reacting with normal matter. Three kinds of neutrinos are known, associated with the electron, muon, and tau particle
Nucleus – the positively charged central core of an atom, consisting of protons and neutrons and containing nearly all its mass
Neutrons – are uncharged particles and do not produce ionization directly. But, their interaction with the atoms of matter can give rise to alpha, beta, gamma, or X-rays which then produce ionization. Neutrons are penetrating and can be stopped only by thick masses of concrete, water or paraffin
Particle – atoms are made up of three particles: protons, neutrons and electrons — which are composed of even smaller particles, such as quarks
Positron – or antielectron is the antiparticle or the antimatter counterpart of the electron
Protons – a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign
Rad – Radiation Absorbed Dose. The basic unit of an absorbed dose of ionizing radiation. One rad is equal to the absorption of 100 ergs of radiation energy per gram of matter
Radioactive dating – technique for estimating the age of an object by measuring the amounts of various radioisotopes in it
Radioactive waste – materials which are radioactive and for which there is no further use
Radioactivity – spontaneous decay of disintegration of an unstable atomic nucleus accompanied by the emission of radiation
Radioisotope – radioactive isotope. A common term for a radionuclide
Radionuclide – radioactive nuclide. An unstable isotope of an element that decays or disintegrates spontaneously, emitting radiation
Rate meter – electronic instrument that indicates, on a meter, the number of radiation induced pulses per minute from radiation detectors such as a Geiger-Muller tube
Transmuted (transmutation) – the changing of one element into another by radioactive decay, nuclear bombardment, or similar processes
Department of Horticulture, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi- 221 005 (India)
Use of Radiation and isotopes in insects 2011 10.5772/2153 Thiago Mastrangelo and Julio Walder Centre for Nuclear Energy in Agriculture (CENA/USP) Brazil
Food and Agriculture Organization of the United Nations, In Action: Nuclear applications in agriculture
Science History Institute Atoms for Peace: The mixed legacy of Eisenhower’s nuclear gambit, Jessie Hicks, Science, Technology, and Society Program, Pennsylvania State University
IAEA International Atomic Energy Agency Radiation in Everyday Life, https://www.iaea.org/Publications/Factsheets/English/radlife