Nav: Home

A fast reactor system to shorten the lifetime of long-lived fission products

November 14, 2017

A team of scientists at Tokyo Institute of Technology (Tokyo Tech) working in collaboration with Tohoku University, Tokyo City University and the Japan Atomic Energy Agency has proposed a novel approach to tackle the problem of radioactive waste disposal.

The new method, published in Scientific Reports, could dramatically reduce the effective half-life (an indicator of the amount of time it takes to bring radioactive materials down to safe levels) of long-lived fission products[1] (LLFPs) from hundreds of thousands of years to within a hundred years.

How to dispose of nuclear waste is one of the biggest dilemmas facing the world today. The issue concerns what to do with radioactive waste after uranium and plutonium have been recovered from spent nuclear fuel using reprocessing methods such as Plutonium Uranium Redox EXtraction (PUREX).

Although burying waste deep underground is widely viewed as the most viable option, a number of strategies are being explored to reduce the stockpile of depleted fuel. One of the most promising is the partitioning and transmutation (P&T) strategy. This involves separating fuel into minor actinides[2] (MAs) and LLFPs followed by the transmutation[3] of MAs and LLFPs into shorter-lived nuclides.

So far, the P&T strategy has been limited by the costly and cumbersome need to separate LLFP isotopes before they can undergo transmutation. Also, some LLFPs, owing to their small neutron capture cross sections, are not able to capture enough neutrons for effective transmutation to occur.

The new study led by Satoshi Chiba at Tokyo Tech shows that effective transmutation of LLFPs can be achieved in fast spectrum reactors without the need for isotope separation. By adding a moderator (or slowing-down material) called yttrium deuteride (YD2), the team found that LLFP transmutation efficiency increased in the radial blanket and shield regions of the reactor. The researchers say that this is due to the moderator's ability "to soften the neutron spectrum leaking from the core".

Chiba and his co-workers focused on six LLFPs: selenium-79, zirconium-93, technetium-99, palladium-107, iodine-129 and caesium-135. Calculations showed that the effective half-lives of these LLFPs could be drastically reduced so that total radiotoxicity at long cooling time domain will be efficiently reduced (see Figure).

In experiments of this kind, the support ratio (that is, the ratio of the transmutation rate to the production rate) is an important indicator of transmutation efficiency. The team showed that support ratios of over 1.0 were achieved for all six LLFPs tested, representing a vast improvement on previous findings.

Using their method, the researchers say that the 17,000 tons of LLFPs now in storage in Japan could potentially be disposed of using ten fast spectrum reactors. Their method also has the advantage of contributing to electricity generation and supporting efforts towards nuclear non-proliferation.
-end-
Technical terms

[1]Long-lived fission products (LLFPs): Radioactive materials with long half-lives produced by nuclear fission. This study concerns the LLFPs selenium-79, zirconium-93, technetium-99, palladium-107, iodine-129 and caesium-135.

[2]Minor actinides (MAs): Elements synthesized in nuclear fuel other than uranium and plutonium, such as neptunium, americium and curium.

[3]Transmutation: A change induced by neutron capture that results in the conversion of LLFPs to short-lived or non-radioactive nuclides.

About Tokyo Institute of Technology

Tokyo Institute of Technology stands at the forefront of research and higher education as the leading university for science and technology in Japan. Tokyo Tech researchers excel in a variety of fields, such as material science, biology, computer science and physics. Founded in 1881, Tokyo Tech has grown to host 10,000 undergraduate and graduate students who become principled leaders of their fields and some of the most sought-after scientists and engineers at top companies. Embodying the Japanese philosophy of "monotsukuri," meaning technical ingenuity and innovation, the Tokyo Tech community strives to make significant contributions to society through high-impact research. https://www.titech.ac.jp/english/

Tohoku University

Tohoku University was established in 1907 as Japan's third national university, and is proud to be recently ranked No.2 on the Times Higher Education 2017 list of top universities in Japan.

Tohoku University has a history of innovation and continues to lead in traditional fields of research, is committed to contributing to its local and global communities, and encourages academic-industry-government cooperation to help strengthen and develop new areas of research. https://www.tohoku.ac.jp/en/

About Tokyo City University

Tokyo City University's predecessor, Musashi Insitute of Technology was founded in 1929, by students seeking an ideal engineering education. The university promotes high-level engineering education and research, and educates engineers that contribute to society.

The university was renamed to Tokyo City University in 2009. In April 2013, the Faculty of Environmental and Information Science was split into the Faculty of Environmental Studies and the Faculty of Informatics, and now has six faculties and eighteen schools. Building on traditions of high quality specialist engineering education, we continue to educate graduates that will be sought after by society.

https://www.tcu.ac.jp/english/

Tokyo Institute of Technology

Related Nuclear Articles:

US nuclear regulators greatly underestimate potential for nuclear disaster
The US Nuclear Regulatory Commission relied on faulty analysis to justify its refusal to adopt a critical measure for protecting Americans from nuclear-waste fires at dozens of reactor sites around the country, according to an article in the May 26 issue of Science magazine.
Visualizing nuclear radiation
Extraordinary decontamination efforts are underway in areas affected by the 2011 nuclear accidents in Japan.
New path suggested for nuclear fusion
Scientists at Rice University, the University of Illinois at Urbana-Champaign and the University of Chile offer a glimpse into a possible new path toward the production of energy through nuclear fusion.
Physics: Toward a practical nuclear pendulum
Researchers from Ludwig-Maximilians-Universitaet (LMU) Munich have, for the first time, measured the lifetime of an excited state in the nucleus of an unstable element.
Researchers model the way into a nuclear future
The main type of nuclear fuel is the uranium oxide pellet composition.
Nuclear CSI: Noninvasive procedure could identify criminal nuclear activity
Determining if an individual has handled nuclear materials is a challenge national defense agencies currently face.
A new method to help solve the problem of nuclear waste
The article, published recently in Open Chemistry may lead to the development of a process to remove uranium from wastewater at the front-end of the nuclear fuel cycle, or even extracting natural uranium from sea water.
Nuclear puzzle may be clue to fifth force
In a new paper, University of California, Riverside theoretical physicist Flip Tanedo and his collaborators have made new progress towards unraveling a mystery in the beryllium nucleus that may be evidence for a fifth force of nature.
New approach to nuclear structure, freely available
The atomic nucleus is highly complex. Understanding this complexity often requires a tremendous amount of computational power.
Nuclear physics' interdisciplinary progress
The theoretical view of the structure of the atom nucleus is not carved in stone.

Related Nuclear Reading:

The Doomsday Machine: Confessions of a Nuclear War Planner
by Daniel Ellsberg (Author)

Shortlisted for the 2018 Andrew Carnegie Medal for Excellence in Nonfiction
Finalist for The California Book Award in Nonfiction
The San Francisco Chronicle’s Best of 2017 List
In These Times “Best Books of 2017”
Huffington Post’s Ten Excellent December Books List
LitHub’s “Five Books Making News This Week”


From the legendary whistle-blower who revealed the Pentagon Papers, an eyewitness exposé of the dangers of America's Top Secret, seventy-year-long nuclear policy that... View Details


Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety
by Eric Schlosser (Author)

**The documentary Command and Control, directed by Robert Kenner, finds its origins in Eric Schlosser's book and continues to explore the little-known history of the management and safety concerns of America's nuclear aresenal.**

The documentary will air on PBS's American Experience on January 10th. 


A myth-shattering exposé of America’s nuclear weapons


Famed investigative journalist Eric Schlosser digs deep to uncover secrets about the management of America’s nuclear arsenal. A groundbreaking account of accidents, near misses,... View Details


Fallout: Disasters, Lies, and the Legacy of the Nuclear Age
by Fred Pearce (Author)

An investigation into our complicated 8-decade-long relationship with nuclear technology, from the bomb to nuclear accidents to nuclear waste.

From Hiroshima to Chernobyl, Fukushima to the growing legacy of lethal radioactive waste, humanity's struggle to conquer atomic energy is rife with secrecy, deceit, human error, blatant disregard for life, short-sighted politics, and fear. Fallout is an eye-opening odyssey through the first eight decades of this struggle and the radioactive landscapes it has left behind. We are, he finds, forever torn between technological hubris... View Details


U.S. Armed Forces Nuclear, Biological And Chemical Survival Manual
by Dick Couch (Author)

Military experts teach you how to survive an attack on American soil, from North Korean missiles to weaponized smallpox

North Korean nukes. Dirty bombs in train stations. Chemical warfare. Americans have more reasons than ever to be afraid. If a nuclear missile strikes, will you know what to do? If a nerve agent is released in your subway system or office building, will you be safe? The U.S. Armed Forces Nuclear, Biological and Chemical Survival Manual gives you the information you need to survive a terrorist attack. It contains the best practices of all the United... View Details


The Logic of American Nuclear Strategy: Why Strategic Superiority Matters (Bridging the Gap)
by Matthew Kroenig (Author)

For decades, the reigning scholarly wisdom about nuclear weapons policy has been that the United States only needs the ability to absorb an enemy nuclear attack and still be able to respond with a devastating counterattack. So long as the US, or any other nation, retains such an assured retaliation capability, no sane leader would intentionally launch a nuclear attack against it, and nuclear deterrence will hold. According to this theory, possessing more weapons than necessary for a second-strike capability is illogical.

This argument is reasonable, but, when compared to the empirical... View Details


Nuclear War Survival Skills: Lifesaving Nuclear Facts and Self-Help Instructions
by Cresson H. Kearny (Author), Don Mann (Introduction), Edward Teller (Introduction), Dr. Eugene P. Wigner (Introduction)

A field-tested guide to surviving a nuclear attack, written by a revered civil defense expert.

This edition of Cresson H. Kearny’s iconic Nuclear War Survival Skills (originally published in 1979), updated by Kearny himself in 1987 and again in 2001, offers expert advice for ensuring your family’s safety should the worst come to pass. Chock-full of practical instructions and preventative measures, Nuclear War Survival Skills is based on years of meticulous scientific research conducted by Oak Ridge National Laboratory.

Featuring a new introduction by... View Details


Atomic Accidents: A History of Nuclear Meltdowns and Disasters: From the Ozark Mountains to Fukushima
by James Mahaffey (Author)

A gripping narrative of nuclear mishaps and meltdowns around the globe, all of which have proven pivotal to the advancement of nuclear science.

From the moment radiation was discovered in the late nineteenth century, nuclear science has had a rich history of innovative scientific exploration and discovery, coupled with mistakes, accidents, and downright disasters.

Mahaffey, a long-time advocate of continued nuclear research and nuclear energy, looks at each incident in turn and analyzes what happened and why, often discovering where scientists went wrong... View Details


Nuclear Physics for Babies (Baby University)
by Chris Ferrie (Author), Cara Florance (Author)

Simple explanations of complex ideas for your future genius!

Written by an expert, Nuclear Physics for Babies is a colorfully simple introduction to what goes on in the center of atoms. Babies (and grownups!) will learn all about the nucleus and the amazing process of nuclear decay. Co-written by Cara Florance, who has a PhD in Biochemistry and a BS in Chemistry with work experience in astrobiololgy and radiation decontamination. With a tongue-in-cheek approach that adults will love, this installment of the Baby University board book series is the perfect... View Details


Nuclear Weapons: 1945 Onwards (Strategic and Tactical Delivery Systems)
by David Baker (Author)

Much misinformation has been published by those who support, as well as those who are against, the continued deployment of nuclear weapons as instruments of deterrence. This book provides an apolitical description of strategic nuclear weapons, how they are designed, how they work, and how they are assigned to different targets in the event of conflict.

As well as a Workshop Manual, this book would be a guide to public understanding expressed in a dispassionate and factual manner for information which many people find hard or impossible to obtain. Nuclear weapons do exist, and they... View Details


Atomic Awakening: A New Look at the History and Future of Nuclear Power
by James Mahaffey (Author)

“Persuasive and based on deep research. Atomic Awakening taught me a great deal."―Nature

The American public's introduction to nuclear technology was manifested in destruction and death. With Hiroshima and the Cold War still ringing in our ears, our perception of all things nuclear is seen through the lens of weapons development. Nuclear power is full of mind-bending theories, deep secrets, and the misdirection of public consciousness, some deliberate, some accidental. The result of this fixation on bombs and fallout is that the development of a... View Details

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

The Person You Become
Over the course of our lives, we shed parts of our old selves, embrace new ones, and redefine who we are. This hour, TED speakers explore ideas about the experiences that shape the person we become. Guests include aerobatics pilot and public speaker Janine Shepherd, writers Roxane Gay and Taiye Selasi, activist Jackson Bird, and fashion executive Kaustav Dey.
Now Playing: Science for the People

#478 She Has Her Mother's Laugh
What does heredity really mean? Carl Zimmer would argue it's more than your genes along. In "She Has Her Mother’s Laugh: The Power, Perversions, and Potential of Heredity", Zimmer covers the history of genetics and what kinship and heredity really mean when we're discovering how to alter our own DNA, and, potentially, the DNA of our children.