Method uses cosmic rays to gather detailed information from inside damaged Fukushima nuclear reactors

Oct 17, 2012
Los Alamos National Laboratory Muon Radiography team members stand in front of the damaged Fukushima Daiichi reactor complex during a visit to determine evaluate whether Los Alamos' Scattering Method for cosmic-ray radiography could be used to image the location of nuclear materials within the reactor buildings.

(Phys.org)—Researchers from Los Alamos National Laboratory have devised a method to use cosmic rays to gather detailed information from inside the damaged cores of the Fukushima Daiichi nuclear reactors, which were heavily damaged in March 2011 by a tsunami that followed a great earthquake.

In a paper in , researchers compared two methods for using cosmic-ray radiography to gather images of nuclear material within the core of a reactor similar to Fukushima Daiichi Reactor No. 1. The team found that Los Alamos' scattering method for cosmic-ray radiography was far superior to the traditional transmission method for capturing high-resolution image data of potentially damaged nuclear material.

"Within weeks of the disastrous 2011 tsunami, Los Alamos' Muon Radiography Team began investigating use of Los Alamos' muon scattering method to determine whether it could be used to image the location of nuclear materials within the damaged reactors," said Konstantin Borozdin of Los Alamos' Subatomic Physics Group and lead author of the paper. "As people may recall from previous nuclear reactor accidents, being able to effectively locate damaged portions of a is a key to effective, efficient cleanup. Our paper shows that Los Alamos' scattering method is a superior method for gaining high-quality images of core materials."

Muon radiography (also called cosmic-ray radiography) uses generated when collide with upper regions of Earth's atmosphere to create images of the objects that the particles, called muons, penetrate. The process is analogous to an X-ray image, except muons are produced naturally and do not damage the materials they contact.

Massive numbers of muons shower the earth every second. Los Alamos researchers found that by placing a pair of muon detectors in front of and behind an object, and measuring the degree of scatter the muons underwent as they interacted with the materials they penetrated, the scientists could gather detailed images. The method works particularly well with highly interfering materials (so-called "high Z" materials) such as uranium. Because the muon scattering angle increases with atomic number, core materials within a reactor show up more clearly than the surrounding containment building, plumbing and other objects. Consequently, the muon scattering method shows tremendous promise for pinpointing the exact location of materials within the Fukushima reactor buildings.

Using a computer model, the research team simulated a with percentages of its core removed and placed elsewhere within the reactor building. They then compared the Los Alamos scattering method to the traditional transmission method. The simulation showed that passive observation of the simulated core over six weeks using the scattering method provided high-resolution images that clearly showed that material was missing from the main core, as well as the location of the missing material elsewhere in the containment building. In comparison, the transmission method was barely able to provide a blurry image of the core itself during the same six-week period.

"We now have a concept by which the Japanese can gather crucial data about what is going on inside their damaged reactor cores with minimal human exposure to the high radiation fields that exist in proximity to the reactor buildings," Borozdin said. "Muon images could be valuable in more effectively planning and executing faster remediation of the complex."

In addition to their potential utility at , muon portals have been deployed to detect potential smuggling of clandestine nuclear materials. These detectors can noninvasively find even heavily shielded contraband in minutes without breaching a container, vehicle or other smuggling device. Los Alamos researchers pioneered the concept shortly after the 9/11 terrorist attacks.

Explore further: IHEP in China has ambitions for Higgs factory

More information: The paper may be found at: arxiv.org/abs/1209.2761

Related Stories

GE defends nuclear plant design

Mar 18, 2011

General Electric defended its 40 year old Mark 1 reactors at the center of Japan's nuclear crisis Friday, saying that early questions about reactor's safety had long been addressed.

No uncontrolled reaction at Fukushima: operator

Nov 03, 2011

The operator of Japan's crippled Fukushima atomic plant Thursday played down fears of an uncontrolled chain reaction at the site, despite the discovery of evidence of recent nuclear fission.

Record-breaking detector may aid nuclear inspections

Mar 14, 2006

Scientists at the Commerce Department's National Institute of Standards and Technology (NIST) have designed and demonstrated the world's most accurate gamma ray detector, which is expected to be useful eventually ...

US experts unsure about Fukushima situation

Mar 28, 2011

US experts have expressed uncertainty about the seriousness of the situation at Japan's Fukushima nuclear complex, steering clear of speculation whether the core of one of the reactors there had been damaged.

Small fire at Japan nuclear lab; no radiation leak

Dec 20, 2011

A building housing an experimental nuclear reactor in Japan caught fire Tuesday, but there was no leak of radioactive materials, officials said, amid nervousness over Japan's atomic industry.

Recommended for you

New approach to form non-equilibrium structures

1 hour ago

Although most natural and synthetic processes prefer to settle into equilibrium—a state of unchanging balance without potential or energy—it is within the realm of non-equilibrium conditions where new possibilities lie. ...

Nike krypton laser achieves spot in Guinness World Records

2 hours ago

A set of experiments conducted on the Nike krypton fluoride (KrF) laser at the U.S. Naval Research Laboratory (NRL) nearly five years ago has, at long last, earned the coveted Guinness World Records title for achieving "Highest ...

Chemist develops X-ray vision for quality assurance

7 hours ago

It is seldom sufficient to read the declaration of contents if you need to know precisely what substances a product contains. In fact, to do this you need to be a highly skilled chemist or to have genuine ...

The future of ultrashort laser pulses

7 hours ago

Rapid advances in techniques for the creation of ultra-short laser pulses promise to boost our knowledge of electron motions to an unprecedented level.

IHEP in China has ambitions for Higgs factory

Jul 23, 2014

Who will lay claim to having the world's largest particle smasher?. Could China become the collider capital of the world? Questions tease answers, following a news story in Nature on Tuesday. Proposals for ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Tausch
1 / 5 (2) Oct 17, 2012
Not macht erfinderisch.
Necessity begets ingenuity.
Hindsight at work.