Just like we learned the first day of class, chemistry is everything. Our class explores the ways chemistry permeates daily life. One of the most fascinating opportunities in Chemistry 101 is observing how chemistry applies to my areas of study. As a student of political science and history, I try to apply the lessons I learn in chemistry to topics within my fields of interest. As such, I explored Valerie Browns’ article “Decades After Bomb-Making, the Radioactive Waste Remains Dangerous” on the Discovery Magazine website. This article explains some of the science behind nuclear weapons technology and the dangers of radioactive waste. And it exemplifies the pervasive nature of chemistry.
In her article, Brown explores the dangers of constructing nuclear weapons – particularly the radioactive waste. She focuses on the Hanford Nuclear Reservation. It was nearly 30 years ago when “the state of Washington and two federal agencies agreed to clean up” the Reservation, where the United States produced plutonium for nuclear weapons starting in the 1940s (Brown). Throughout this process, half a trillion gallons of chemically toxic and radioactive waste was dumped on the ground or injected into groundwater, some of which has reached the Columbia River (Brown). But that is not the extent of the problem. Additionally, 177 underground storage tanks” contain another “56 million gallons of mixed radioactive and chemical waste from the processing of irradiated fuel” (Peterson, et al). This makes Hanford perhaps “the most toxic place in America” (Peterson, et al). And here lies the crux of Brown’s article: safe disposal. As Brown notes, the task of safe disposal remains unfinished. But it is imperative we try to mitigate the damage and “prevent further environmental and human risk for centuries to come” (Brown).
In 1943, the world’s first plutonium production reactor was built at Hanford. During the last years of World War II and throughout the Cold War, the United States produced around 67 metric tons of plutonium at Hanford (Brown). But how does this happen? Scientists at Hanford “had to bombard uranium (U-238) with neutrons” to create plutonium-239, which would then be used to create nuclear weapons (Morris). These bombardments are part of a process called nuclear fission. Fission occurs when a neutron is shot at “the nuclei of certain heavy atoms” which causes the atoms to “split into smaller, lighter nuclei, releasing excess energy in the process” (ucsusa.org). This process produces a vast chain of fission products such as the highly radioactive isotopes cesium-137 and strontium-90, some of which have incredibly long half-lives Peterson, et al). For example, plutonium-239 has a half-life of 24,100 years; however, “substances with shorter half-lives decay more quickly than those with longer half-lives, so they emit more energetic radioactivity” (nrc.gov). This exemplifies the main concern behind Brown’s article: the unresolved solutions to chemical waste.
Once plutonium is produced, it must be separated from the uranium so it can be used in nuclear weapons. But the Manhattan Project was the first of its kind; scientists were unsure of how to store or otherwise effectively remove the waste. Thus, great amounts of wastes were produced before “Hanford experts devised the efficient and widely used PUREX process” (Brown). The PUREX process is a method of effectively “separating uranium and plutonium from irradiated nuclear fuels” (Herbst, et al). This process “relies on changing the plutonium’s oxidation state to achieve the desired separation and decontamination from the uranium and fission products, from the fuel, and from the process chemicals and corrosion products from plant operations” (Delegard and Jones). Other separation processes were also utilized, such as the bismuth phosphate process (BiPP) and the reduction-oxidation (REDOX) process. Despite development of the PUREX process and other methods, plutonium production at Hanford stopped in 1987, and construction of the Hanford Tank Waste Treatment and Immobilization Plant began in 2000 (Brown). This plant aims to resolve the long-term waste problem through vitrification, whereby experts mix chemical waste with other materials that will form glass when exposed to high temperatures. This conversion from liquid radioactive and chemical waste, like what is found at Hanford, into a solid and stable glass eliminates the environmental risks presented by the waste (hanfordvitplant.com). But the vitrification plant is not complete, and the waste problem in the tanks keeps compounding.
One of the trickiest problems at Hanford is that there are “thousands of compounds and the chemistry is constantly changing” and many compounds have formed “that were never originally put in the tanks” (Brown). This is due to plutonium’s odd behavior. Elements to the left of plutonium on the periodic table are more willing to share electrons, whereas those to the right have a higher electronegativity and thus are less willing to share. Interestingly though, “plutonium can go either way: Put it under pressure and it will be hands across the water with those left-hand elements; put it in a vacuum and it closes its borders like its right-hand neighbors” (Brown). This behavior befuddles many experts and creates uncertainty – which can especially problematic when it comes to deciphering how to store chemical waste safely. And processing this incessantly changing waste will take more than 40 years to complete (Robertson, et al). Yet, experts are confident in their ability to vitrify and contain the Hanford waste and solve one of the major public safety concerns now facing many Americans.
In short, the United States’ history of nuclear weapons production engendered an incredible amount of radioactive waste. This problem threatens many Americans today, but the chemistry behind such waste elucidates the longevity of this danger. This is a problem that government agencies, private actors, and even individuals must cooperate to understand and solve. Thus, it is important for everyone to have an understanding of chemistry because chemistry is, in fact, everything.