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Category Archives: Nuclear Materials

EXIT — A Good Sign of Radiation

Maureen Conley
Public Affairs Officer

refresh leafMost people know radioactive energy can be harnessed to provide electricity and even to diagnose and treat certain illnesses. But would it surprise you to learn that radioactive materials also perform an important safety function by lighting emergency EXIT signs?

Look for the EXIT sign the next time you go to work, school, a sporting event, religious service, the movies, or the mall. If the sign glows green or red, chances are it contains a radioactive gas called tritium. The tritium, a radioactive isotope of hydrogen, is sealed into glass tubes lined with a chemical that glows in the dark. Tritium emits low-energy radiation that cannot penetrate paper or clothing and even if inhaled, it leaves the body relatively quickly. As long as the tubes remain sealed, the signs pose no health, safety, or security hazard.

exit3We estimate there are more than 2 million of these signs in use in the United States. To ensure safety in handling and the manufacturing process, we and our Agreement State partners regulate the manufacture and distribution of tritium EXIT signs. Companies have to apply for and receive a license before they can manufacture or distribute one of these signs.

But because the signs are designed to be inherently safe, the NRC does not require any special training before a building can display the signs. Users are responsible for meeting the requirements for handling and disposal of unwanted or damaged signs and for reporting any changes affecting the signs.

exit2Proper handling and disposal is the most important safety requirement for these signs. A damaged sign could contaminate the immediate area and require an expensive cleanup. That is why broken or unwanted signs must be return to a licensed manufacturer, distributer, radioactive waste broker or radioactive waste disposal facility.

Tritium EXIT signs are one of several types of radioactive consumer products that we allow. These products can be produced and sold ONLY if they have a benefit that outweighs any radiation risk. See our earlier blog post for more information on how we regulate these products.

REFRESH is an occasional series where we revisit previous blog posts.

IMPEP — Evaluating the NRC’s Radioactive Materials Program

David Spackman
Health Physicist

For the NRC and each of the 37 states that regulate radioactive materials under agreements with us, a time comes every few years when we start talking about “IMPEP.” The acronym is spoken about as frequently as the top 10 new words added to Webster’s Dictionary every year – that is to say a lot.

IMPEP may be very easy to say, but understanding its true value requires a closer look.

IMPEP stands for the Integrated Materials Performance Evaluation Program. Think of it like an audit. It is the NRC’s primary tool for assessing how well radioactive materials programs are agreementstatenesperforming. Every Agreement State and NRC program is evaluated under IMPEP every four to five years. A rotating team of experts from the Agreement States and the NRC do the reviews. The teams focus on specific areas of a radioactive materials program that have the potential to affect public health and safety. The reviews are very detailed, typically lasting a full week.

Once an IMPEP review team has looked at everything they need to see on-site, they document their findings. They write a report and recommend a “grade” on the program’s performance to the Management Review Board, which is comprised of senior NRC managers and a state program manager who keeps in touch with the other Agreement States. The board holds a public meeting to talk about what the team saw and assigns the overall program rating: “Satisfactory,” “Satisfactory but Needs Improvement,” or “Unsatisfactory.”

Recently it was the NRC’s turn to undergo an IMPEP review. From Dec. 8-11, a team of experts from Ohio, Tennessee, and the NRC reviewed the NRC’s Sealed Source and Device (SS&D) Evaluation Program. This program performs engineering and radiation safety evaluations of sealed radioactive sources and the devices that use them.

Sealed sources are just what the name says—radioactive sources sealed in a capsule to prevent leakage or escape of the material. The devices are used for many things, but generally they measure something, such as soil density, fluid levels, the thickness of a pipe, and whether metal and welds are sound. They can also help to map geologic formations from inside a gas or oil well. The NRC needs to do adequate technical evaluations of SS&D designs to ensure they’ll maintain their integrity and their designs are adequate to protect public health and safety.

During the four-day IMPEP review at NRC Headquarters, the team looked at the NRC program’s technical quality, staffing and training, and any defects or incidents involving SS&Ds. Most of the work was done through in-depth staff interviews and targeted document reviews. S

Since finishing the evaluation in mid-December, the team has drafted their report. They expect to recommend to the board that the NRC’s SS&D program be rated Satisfactory – the highest possible rating. Furthermore the review team commended NRC staff for performing very competent technical SS&D reviews. Although this is an excellent result so far, there is still one more important step to complete the IMPEP review process – the public meeting.

This meeting allows the review team to present its findings and formally recommend the overall program rating. While the structure of these meetings is simple, it is very common to see a spirited discussion of the strengths, weaknesses, innovations and shortcomings of the program under review.

This is where the true value of IMPEP is laid bare. If all goes right, the end result is improving a program’s ability to protect public health and safety and the environment – even if the program gets the highest rating.

The MRB’s public meeting to discuss NRC’s SS&D program will be held at NRC Headquarters in Rockville, Md., on March 5, 2015. The meeting details are available on the NRC website at http://meetings.nrc.gov/pmns/mtg. We encourage members of the public to come or listen in by phone.

Hitting the Road – How the NRC Makes Sure Radioactive Material Is Shipped Safely

Bernard White
Senior Project Manager

LWT in Air 2

The NAC LWT transport package Photo courtesy of NAC International

In September 2013, we talked about transportation of spent nuclear fuel and how we know it is safe. This month, we want to discuss the safety basis for transporting other types of radioactive material.

The NRC recently approved a package to transport high enriched uranyl nitrate. This material is left over from the production of medical isotopes used in millions of diagnostic procedures every year. This package is to be used to bring material currently stored in Canada, where the isotopes were made, to the Savannah River site in South Carolina. The shipments are part of a DOE program to take back high enriched uranium from countries to which the U.S. supplied it.

Our review did not address whether the shipment should be made. Nor is it specific to any route. It just looked at whether the proposed shipping package design meets our requirements for safe transport. We rigorously reviewed the information submitted by the cask designer, NAC International. We asked four sets of detailed questions and thoroughly reviewed the applicant’s responses. After two years of review and two face-to-face meetings, we have answers to all our questions and we’re satisfied that the package design meets all NRC requirements for safe transport.

The high enriched uranyl nitrate, which is a liquid, will be transported using special containers that were designed to prevent leakage. To ensure they do not leak, the containers are leak tested after fabrication and prior to transport, each time the container is filled. These containers must also be replaced once they have been in use for 15 months. Together, these requirements give the NRC confidence that the containers will not leak.

These leak-tight containers will be placed into specially-designed packages for transport. This package design has been used for 25 years to safely transport a wide variety of radioactive materials. The inner containers and the outer packaging together make up the transport package.

Our review of this transport package design gives us confidence that, even if there were to be a transport accident, radioactive material will not leak from the package; dose rates will not be high enough to cause harm to anyone; and a nuclear chain reaction will not occur. Packages are evaluated for conditions that mirror normal transportation as well as the forces the package may experience in a severe accident.

The conditions assessed for routine transport include rain, hot and cold temperatures, a drop that may occur during handling, and the vibration that we all feel in a car or riding on a train.

For accident conditions, the package must be shown to be able to withstand forces that are more severe than in a real-world accident. This is done by testing or evaluating the package in a sequence of stringent tests. We discussed these tests in detail in our September 2013 blog.

This package has been shown to be able to safely transport contents that are much heavier and more radioactive than the high enriched uranyl nitrate, including spent nuclear fuel. The dose rates from the package containing liquid uranyl nitrate will be much lower than when the package is loaded with spent fuel.

For all these reasons, the NRC Is confident the package design meets all our requirements for safe transport. We follow the same review process for every transport package design we receive. In every case, we make sure we thoroughly understand the design and all the analyses in the application. We ask questions, if necessary, and often perform our own analysis. In some cases, including this one, we impose special conditions to give added assurance of safety. Only when we are satisfied a design meets every NRC requirement will we issue an approval.

Jefferson Proving Ground – the NRC’s Role

By Stephen Lemont
Senior Environmental Project Manager

Most people think of nuclear reactors when they think of the NRC. Some may think of nuclear medicine or uranium. Many would be surprised to know we are also involved in regulating radioactive materials at U.S. military sites.

Although nuclear weapons are completely outside our purview, some military sites need an NRC license to possess and use certain nuclear materials. For example, the Army has a license to possess depleted uranium (DU) at a site in Indiana called Jefferson Proving Ground.

The Army began using the 56,000-acre site in 1941 to test fire all sorts of conventional munitions. The Army fired more than24 million rounds before testing came to an end in 1994 and the installation closed in 1995 as a result of the Base Realignment and Closure Act. Today, the Army still owns about 51,000 acres of the original site, but nearly all of that is managed as a wildlife refuge. The Indiana Air National Guard uses another part of the site as an air-to-ground bombing training range. The 51,000-acre area contains unexploded ordnance —explosive munitions that could still go off—and live detonators, primers and fuzes, and can’t ever be used for farming, housing or commerce.

duPictureIn the early 1980’s, the NRC got involved with the site when the Army wanted to test DU rounds there. The DU in these rounds is able to penetrate the armor on a tank. Over a 10-year period, the Army fired about 220,000 pounds of DU projectiles into a 2,080-acre area known as the DU Impact Area. The Army still has its NRC license for the DU and now wants to decommission the DU Impact Area, which lies within the 51,000 acres with unexploded ordnance.

The Army has proposed a plan for decommissioning. It has asked the NRC to terminate the license, with certain restrictions as allowed under our regulations. The NRC is in the early stages of reviewing the proposal.

About 162,000 pounds of DU remain in the DU Impact Area. There is also a high density of unexploded ordnance in this area. The Army proposes to leave the DU and unexploded ordnance in place because cleanup would be very dangerous and very expensive. To keep people out of the Jefferson Proving Ground site, the Army says it will keep the current access barriers—including a perimeter fence with padlocked gates and security warning signs—as well as legal and administrative controls.

The NRC met with the public near the site in early December to discuss the Army’s request. We wanted to hear people’s comments and concerns about the environmental aspects of the Army’s plan. We transcribed the meeting to record these statements. We have also taken written public comments.

And, we will consider this input during our independent review of the Army’s proposal. Our analyses and conclusions will be documented in a draft Environmental Impact Statement that explains everything we looked at. We’ll publish the draft for comment and discuss it at a future public meeting. We will consider all the comments we receive on the draft as we put together a final Environmental Impact Statement. The final document will discuss the comments and how we addressed them.

Our process also includes a separate review of the safety impacts of what the Army is proposing. We will publish those findings in a Safety Evaluation Report. Once both the environmental and safety reviews are complete, we will be able to make a decision on the Army’s request.

Local residents told us they want the Army to monitor the environment even after the license is terminated. Others told us they want the Army to clean up the site. Our environmental review will look at those alternatives. People were also concerned about radiation. Our review will make sure the Army’s plan meets all NRC requirements to protect public health and safety.

Blue Topaz — The Irradiated Gemstone

Maureen Conley
Public Affairs Officer

There are a lot of great things about having a November birthday. The heat of summer is over but winter hasn’t set in so the weather can be magnificent. When the leaves are changing, the landscape is even more beautiful than in spring. It is the month of football, first frosts, harvesting the last of the summer vegetable garden, and my favorite holiday, Thanksgiving. But the one thing I never liked about my November birthday was my birthstone—topaz.

topaz 1Orange is just not my favorite color. I was always jealous of my family members, whose stones were so much prettier—amethysts in February, diamonds in April, and sapphires in September. Then one year I received as a gift some earrings with a beautiful blue stone. That was my introduction to blue topaz.

I was so happy to discover there was an alternative to the traditional orange topaz, I never thought to wonder what was behind the blue color. I figured topaz just came in blue, too.

Well it turns out blue topaz can be found in nature but it is very rare. Most blue topaz on the market has been exposed to radiation.

This is no cause for alarm. Irradiated gemstones are not harmful. Because they may be slightly radioactive immediately after their treatment, the NRC regulates the distribution of these products to ensure public health is protected. Any measureable radiation decays away within a couple months. Treated gemstones are set aside and are not sold until the radioactivity falls far below levels that can impact public health.

Distributors of irradiated gemstones must have an NRC license, which requires them to do radiological surveys before selling the gems. Their sophisticated instruments can detect very low levels of radiation. Once the radiation is low enough, no further licensing is required.

topaz 1Topaz is not the only gemstone treated with radiation to change its color. Diamonds, pearls and other gemstones are sometimes irradiated to change their color. In general, the longer stones are exposed to radiation, the deeper and more attractive the color.

Incidentally, not all radiation treatments applied to gemstones make them radioactive. If they are bombarded with neutrons, as in a nuclear reactor or accelerator, trace elements in the stones can become “activated” or radioactive. But gemstones can also be treated using gamma radiation (high-energy photons), which does not make them radioactive.

If your holiday shopping list includes jewelry this year, don’t be afraid of irradiated gemstones. The NRC license ensures they don’t reach the market until they are completely safe.

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