Atanackovic J.,Chalk River Laboratories |
Kramer G.H.,Human Monitoring Laboratory |
Hogue M.,Savannah River Site
Applied Radiation and Isotopes | Year: 2013
An MCNP model of a pair of planar HPGe detectors (designated as: detector 3 and detector 4), that are used for routine lung counting at AECL, was developed. The model was benchmarked against experimental results, where a multi-line 152Eu source was counted in several different geometrical arrangements. The best agreement for both detectors was achieved when side and back dead layers (of both detectors) were quadrupled, with respect to the ones quoted by their manufacturer (Canberra). In the case of detector 4, the agreement between simulated and measured spectra was within 4%, throughout the whole γ-spectrum, spanning 70-1600keV. The same was true for detector 3 at the lower end of the γ-spectrum. However, at the high end of the γ-spectrum, the agreement was within 7% and 12% for 152Eu γ-lines at 778.9 and 1408.01keV. © 2013. Source
"WASHINGTON -- In her job at the Savannah River Site nuclear weapons plant in South Carolina, Sandra Black was responsible for looking into concerns raised by employees about everything from health and safety to fraud, abuse, harassment and retaliation. But in fall 2014, when federal investigators with the Government Accountability Office asked her whether she had the necessary independence to do her job, Black says she answered truthfully: She told them her supervisors had interfered with her work and had tried to intimidate her into changing her findings if they validated employees’ complaints. Black disclosed her conversation with the GAO investigators to her bosses. A few weeks later, on Jan. 7, 2015, she was fired."
TOKYO Japan will load weapons-grade plutonium onto a ship as early as this weekend to send to the United States, in what will be largest such shipment of the highly dangerous material since 1992, Greenpeace said on Friday. The shipment of 331 kilograms of plutonium, enough to make about 50 nuclear weapons, will be loaded in Tokai Mura northeast of Tokyo onto the Pacific Egret, an armed British ship, and transported to the U.S. Department of Energy's Savannah River Site in South Carolina, the environmental group said. Shipments of plutonium are highly sensitive because the material can be used in advanced nuclear weapons or as a so-called dirty bomb. In Japan, public sensitivity is also high because the country is the only nation to be bombed with nuclear weapons. The U.S. embassy in Tokyo declined to comment. The shipment is a tiny portion of the nearly 50 tonnes of plutonium Japan holds. Most of Japan's plutonium comes reprocessing spent nuclear fuel burned in the country's reactors. All but two of Japan's reactors have been shut down since the Fukushima nuclear disaster of 2011. The plutonium being shipped this weekend was supplied by the United States, the United Kingdom, and France for the Japan Atomic Energy Agency's Fast Critical Assembly project in Tokai Mura, according to the International Panel on Fissile Materials. The agreement to transfer the material to the United States was reached in March 2014, according to the panel's website. A spokesman at the Japanese atomic agency declined to comment, citing security reasons.
The demand has the potential to embarrass the Obama administration a week before it hosts an important summit on nuclear non-proliferation and undermine what so far has been viewed as a success in keeping weapons-grade material safe. The ship loaded with weapons-grade plutonium left Japan for a Department of Energy site in South Carolina on Tuesday in what is the largest such shipment of the highly dangerous material since 1992, the environmental group Greenpeace said. The shipment "puts South Carolina at risk for becoming a permanent dumping ground for nuclear materials," Haley said in the letter dated March 23. "Therefore, stop shipment or re-route this defense plutonium. God bless." A representative for the U.S. Department of Energy said it is reviewing Haley's letter but cannot comment on matters under active litigation. The state has sued the department over the federal government's plans to scrap a plutonium recycling plant that has been under construction for years in the state. The dispute comes as Washington prepares to host the Nuclear Security Summit March 31 to April 1. The plutonium being shipped was supplied by the United States, Britain and France for the government-owned Japan Atomic Energy Agency's Fast Critical Assembly research project in Tokai Mura, according to the International Panel on Fissile Materials. The agreement to transfer the material to the United States was reached in March 2014 at a previous non-proliferation summit, the panel said on its website. A South Carolina-based environmental advocacy group said the shipment "only exacerbates the plutonium storage and disposition problems at" the department's Savannah River Site, a 310-square mile (500 square kilometers) area bordered by the Savannah River and Georgia. "The U.S. Government has done a poor job of explaining why this material is being taken to SRS,” Tom Clements, director of SRS Watch, said in a statement. The 331 kilograms (730 pounds) on board the British-owned Pacific Egret is only a tiny proportion of the nearly 50 tonnes (55 tons) of plutonium held by Japan. Japan wants to use the plutonium extracted from spent fuel in nuclear plants as fuel for modified reactors. But with nearly all the country's units still shut down in the wake of the Fukushima nuclear disaster five years ago and no schedule for further restarts there is little use for the material. Only a few reactors can take plutonium as fuel. A homegrown reprocessing plant being built in northern Japan, which has relied on the British and French to extract plutonium from spent uranium fuel rods, also has the potential to add to the stockpile, although its start has been repeatedly delayed. The plutonium being shipped, enough to make about 50 nuclear weapons, was taken from the nuclear research center in the port town of Tokai Mura near Tokyo, for transport to South Carolina. The website www.vesselfinder.com said the ship is a nuclear fuel carrier. Shipments of plutonium are highly sensitive because it can be used in nuclear weapons or to make a so-called dirty bomb. In Japan, public sensitivity is also high because it is the only country that has been attacked with nuclear bombs. Japan is also the only nation without atomic weapons with significant amounts of plutonium, which has led to constant criticism from neighboring countries, scientists and others. China, a nuclear weapons state, this week said Japan should abide by its non-proliferation obligations. "Japan is still stockpiling a large amount of other sensitive nuclear materials, including separated plutonium and highly enriched uranium. This certainly is an issue for the international community to be concerned about,” Chinese Foreign Ministry spokeswoman Hua Chunying said on Tuesday. Thomas Countryman, an assistant U.S. secretary of state in charge of non-proliferation, has called into question the renewal of an agreement between Washington and Tokyo that allows Japan to reprocess and produce weapons-grade plutonium. The agreement is due to be extended in 2018, but with a new U.S. administration starting in January its status is unclear. "We think that there are genuine economic questions where it's important that the U.S. and its partners in Asia have a common understanding of the economic and non-proliferation issues at stake before making a decision about renewal of the 1-2-3 Agreement, for example, with Japan," Countryman told a Senate hearing last week.
The 331 kg (730 lb) of plutonium, enough to make about 50 nuclear weapons, was taken from a nuclear research center in the port town of Tokai Mura, and left on a British ship, the Pacific Egret, for transport to the U.S. Department of Energy's Savannah River Site in South Carolina, Greenpeace said. The website www.vesselfinder.com said the ship is a nuclear fuel carrier. The Japan Atomic Energy Agency (JAEA), which is the government agency responsible for the nuclear material, has not commented on the Greenpeace statement. An agency spokesman cited security reasons. The U.S. embassy in Tokyo also declined to comment. Shipments of plutonium are highly sensitive because it can be used in nuclear weapons or to make a so-called dirty bomb. In Japan, public sensitivity is also high because it is the only country that has been attacked with nuclear bombs. The shipment is a tiny portion of the nearly 50 tonnes of plutonium Japan holds. Most of it comes from reprocessing spent nuclear fuel burned in its reactors at power stations. All but two of Japan's reactors have been shut since a meltdown at a nuclear plant in Fukushima, north of Tokyo, after a powerful earthquake and tsunami in 2011. The plutonium being shipped was supplied by the United States, Britain and France for the JAEA's Fast Critical Assembly project in Tokai Mura, according to the International Panel on Fissile Materials. The agreement to transfer the material to the United States was reached in March 2014, the panel said on its website.