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Category Archives: Nuclear Materials

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.

Seeing Clearly Through the Cloud – Assessing a Leak at Honeywell

Joey Ledford
Public Affairs Officer
Region II

 

The sound of alarms during the evening of Oct. 26 at the Honeywell Metropolis Works alerted workers and those living closest to the Metropolis, Ill., site that something out of the ordinary had occurred.

Honeywell MetropolisThe plant, a fixture in the southern Illinois river town since 1958, is the nation’s only uranium conversion plant. It converts raw uranium, or yellowcake, into uranium hexafluoride, or UF6, which is enriched at other facilities into fuel for commercial nuclear power plants.

That Sunday evening, Honeywell experienced a leak of UF6. The leak occurred in a cold trap inside the Feed Materials Building. (A cold trap is a large tank where raw UF6 accumulates so it can be cooled and solidified and later heated and drained during normal plant operations.) The leak occurred while the cold trap was heated and was being drained.

An operator put on a respirator and confirmed the leak at 7:24 p.m. local time. Plant emergency responders were dispatched to shut down operations and account for all personnel. Honeywell declared a “plant emergency,” but did not declare an “Alert,” the lowest NRC emergency classification for fuel facilities. Honeywell advised the NRC the cold trap was isolated, vacuum devices were being used to collect leakage, and the material in the device was cooling by 8:15 p.m.

 No one was injured and Honeywell declared “all clear” status at 2:16 a.m. Monday.

People outside the plant reported that a cloud was visible, coming from the building even before mitigation spray towers were activated. Those towers generate gigantic streams of water and water vapor into the air inside and outside the plant, and contributed to clouds that were seen after they were activated.

The NRC quickly dispatched a senior fuel facilities inspector to Honeywell to independently assess what had occurred and how Honeywell had responded. Another inspector later travelled to the facility to gather more information.

After reviewing records, interviewing Honeywell employees and examining the affected areas, the NRC has reached a number of preliminary conclusions:

  • The leaking UF6 vaporized and interacted with moisture inside the Feed Building, which converted it into UO2F2 (a solid form of uranyl fluoride, a yellow powder).
  • The uranyl fluoride was contained within the Feed Building and settled within a few feet of the cold trap leak.
  • The chemical conversion process also produced hydrogen fluoride gas, some of which was visible emanating from the building.
  • The mitigating sprays outside the building were aimed at the windows in an effort to keep the hydrogen fluoride from getting offsite.
  • Honeywell implemented their emergency plan, assessing the event and taking the actions spelled out in the plan, including stopping the leak.
  • A potential violation was identified related to the emergency classification of the event and remains under agency review.
  • The hydrogen fluoride gas that left the building had no health effects for workers or nearby residents.

Honeywell plant management has agreed to the terms of a Confirmatory Action Letter issued by the NRC to not restart the facility until the NRC is satisfied that the company has appropriately addressed the emergency classification issues raised during and after the event. Honeywell has also agreed to a number of corrective actions, including revised training and emergency procedures. The NRC is monitoring an emergency exercise at Honeywell to ensure that corrective measures are in place.

The NRC will remain vigilant and will closely inspect the corrective actions made by Honeywell this week under the CAL. As well, the NRC will consider potential enforcement actions stemming from the event.

Update: You can read the latest Preliminary Notification here.

REFRESH: Do Not Fear Your Smoke Detector – It Could Save Your Life

Maureen Conley
Public Affairs Officer

refresh leafWe sometimes get calls from people worried about radiation from smoke detectors in their homes. There are many reasons why the public need not fear these products.

Ionization chamber smoke detectors contain very small amounts of nuclear material. They might use americium-241, radium-226 or nickel-63. These products detect fires early and can save lives. [We explained how smoke detectors work in greater detail in an earlier blog post.]

The Atomic Energy Commission granted the first license to distribute smoke detectors in 1963. These early models were used mainly in factories, public buildings and warehouses. In 1969, the AEC allowed homeowners to use smoke detectors without the need for a license. Their use in homes expanded in the early 1970s. The NRC took over from the AEC in 1975.

Makers and distributors of smoke detectors must get a license from the NRC. They must show that the smoke detector meets our health, safety and labeling requirements.

smokedetectornewMost smoke detectors sold today use 1 microcurie or less of Am-241. They are very safe. A 2001 study found people living in a home with two of these units receive less than 0.002 millirems of radiation dose each year. That is about the dose from space and the earth that an East Coast resident receives in 12 hours. Denver residents receive that dose in about three hours. These doses are part of what is known as “background radiation.”

The radioactive source in the smoke detector is between two layers of metal and sealed inside the ionization chamber. The seal can only be broken by the deliberate use of force, which obviously we discourage. Still, even then it would result in only a small radiation dose. The foil does not break down over time. In a fire, the source would release less than 0.1 percent of its radioactivity. It’s important to understand that none of the sources used in smoke detectors can make anything else radioactive.

What about disposing of smoke detectors? A 1979 analysis looked at the annual dose from normal use and disposal of Am-241 smoke detectors. The study used actual data and assumptions that would overstate the risk. It allowed the NRC to conclude that 10 million unwanted smoke detectors each year can be safely put in the trash.

The 2001 study looked at doses from misuse. It found that a teacher who removed an americium source from a smoke detector and stored it in the classroom could receive 0.009 millirems per year. If the teacher used the source in classroom demonstrations, handling it for 10 hours each year would give less than a 0.001 mrem dose. A person who swallowed the source would receive a 600 mrem dose while it was passing through the body.

I hope this information allays concerns. Unless you remove and swallow the source, your dose from a smoke detector could not be distinguished from what you get throughout your day. And that smoke detector could save your life.

 REFRESH is an occasional series during which we revisit previous blog posts. This originally ran on June 11, 2013. We are rerunning now in honor of Fire Prevention Week. According to the National Fire Protection Association, the week was established to commemorate the Great Chicago Fire, which killed more than 250 people, left 100,000 homeless, destroyed more than 17,400 structures and burned more than 2,000 acres. This year’s theme is Smoke Alarms Save Lives: Test Yours Every Month.

 

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