Tag Archives: radioactivity

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Carbon dating: A window to the world

As global warming causes the Earth’s permafrost to melt, scientists are uncovering some astonishing finds from deep beneath the ice.

Producing an accurate age of these treasures is a key step for archaeologists, made possible through carbon dating, a process of dating organic material as far back as 60,000 years using nuclear technology.

One well-known discovery was “Ötzi the Iceman,” who became a bona fide scientific celebrity after being found in 1991 by two German hikers 3,210 metres above sea level in the Ötztal Alps on the Austrian-Italian border. The mummified corpse was partly entombed in the ice and thought at first to be a fallen mountaineer or Italian soldier from one of the world wars.

It wasn’t until scientists used carbon dating to determine Ötzi’s age that they discovered he had perished 5,300 years earlier during the late Neolithic period. In 2018, researchers published a detailed analysis of the tools discovered alongside Otzi’s body. These tools would have only given clues as to Ötzi’s age without the help of carbon dating.

The ability to carbon date organic objects was first discovered in 1946 by Willard Libby, a professor of chemistry at the University of Chicago. He determined that carbon-14, a radioactive isotope of carbon naturally found in the atmosphere, was absorbed by green plants and the animals that ate them.

Libby correctly theorized that if the amount of carbon-14 in an object could be detected, its age could be known by calculating the half-life (about 5,730 years) or rate of decay of the isotope, a process that begins when a living organism dies. Once this occurs, carbon-14 is no longer absorbed and the existing isotope count begins to steadily diminish. In other words, the older the specimen, the less carbon-14 will be present.

Until Libby’s discovery, the age of objects could only be determined in relation to the surrounding site by examining the geographic layers where an artifact was found.

New applications have developed for the technique as well. Carbon dating has been used to successfully confirm alleged art forgeries such as the painting by French cubist Fernand Léger and Robert Trotter’s forgery of Sarah Honn’s artwork.

Both were identified as fake after analyzing the radioactive forms of carbon-14 in the canvas and paint to establish whether there was a realistic correlation between their ages. Forgers are well known for using old canvas to appear authentic but have no choice but to use much newer paint.

Scientists also use carbon dating to study monarch butterfly migration routes from Canada to Mexico and back. The method solved a longstanding mystery about why some monarchs are found on the East Coast as well as the traditional interior.

Researchers studied 90 butterfly samples from 17 sites from Maine to Virginia along with 180 samples of milkweed, which monarch larvae feed on. This revealed where the monarchs were born and their age when they consumed the milkweed.

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Radioactivity Fighting Cancer

Brachytherapy, or internal radiation, is proving successful in treating certain tumors.

Cancer is very complex. Curing patients without causing side effects means that the treatments must be very targeted.

BrachytherapyMen“Not all cancers are the same,” according to Dr. Michael Milosevic, a radiation oncologist at the Princess Margaret Cancer Center in Toronto. “Cancer is not one diagnosis. Each individual cancer is different.”

For patients diagnosed with cancer, surgery, radiation treatment and drug treatment (chemotherapy) are frequently used. External radiation, a beam targeted to a tumor that travels to the tumor from outside of the patient’s body comprises 80-90% of radiation therapies.

Brachytherapy, on the other hand, involves inserting the radiation into the center of the tumor and irradiating the cancer cells from the inside out.  The treatment has proven successful in fighting prostate and cervical cancers.

“With brachytherapy, you can kill the cancer but spare the normal surrounding areas,” says Milosevic. “The likelihood of curing the cancer goes way up and the side effects way down.”

There are two methods of using Brachytherapy-temporary and permanent implants

Temporary implants use special catheters inserted into the tumor. They connect to a machine to deliver the radiation treatments. A temporary implant is a day procedure. The radiation is delivered over a very short period of time, usually a few minutes, and then the catheters are removed.

BrachytherapyWomenPermanent implants directly insert small radioactive “seeds,” each about the size of a grain of rice, into the tumor. In the case of prostate cancer treatment, about 100 seeds are placed into the prostate gland, usually when the patient is asleep.  The seeds remain in the prostate gland for the remainder of the patient’s life and give off a continuous flow of radiation that is highest immediately after insertion and declines to zero over a few months.

The uses for brachytherapy continue to develop. It has proven useful in treating some breast, head and neck cancers. Perhaps one of the biggest developments, as Dr. Milosevic points out, is the shift to magnetic resonance imaging (MRI). The Princess Margaret Cancer Centre  is home to three MRI units that help to deliver brachytherapy.

“With Brachytherapy you put the radiation in the center of the tumor so you can kill the cancer but spare the normal surrounding areas. The likelihood of curing goes way up and side effects go down.”

Nuclear Safety

Radioactive Packaging Put to the Test, Passes with Flying Colours

By Romeo St-Martin
Digital Media Officer
Canadian Nuclear Association

The recent incident at the port of Halifax is a real-life example of the high level of safety involved in the packaging and transport of nuclear substances in Canada and around the world.

On Thursday, four steel cylinders encased in concrete containing uranium hexafluoride fell about six metres from inside a container at the Fairview Container Terminal at the port, landing in a contained area of a ship.

URENCO has said the cylinders came from its enrichment facility in the United Kingdom. The shipment was bound for the U.S.

Fire and port officials evacuated the terminal and it remained closed until radiation experts confirmed there was no leak of radiation the following day.

Halifax Fire and Emergency Executive Fire Officer Phil McNulty was quoted in a Canadian Press story as saying the containers are extremely durable.

“The safety redundancies built in for the transportation of nuclear materials are unbelievable,” he said.

“If this wasn’t done properly, we wouldn’t be singing the song we’re singing now.”

Every day, Canadians working in nuclear ship thousands of packages of radioactive material, many of them across the world. In five decades, there has been no transportation incident with significant radiological damage to people or the environment.

According to the Canadian Nuclear Safety Commission, packages requiring certification have to undergo stringent testing. Testing must simulate both normal and accident conditions of transport. The tests can include free-drop testing, puncture testing, thermal testing, and aircraft accident simulations.

The following video illustrates drop testing in Germany.

Testing methods in Canada are very similar, if not identical, to methods used by other international regulatory bodies.