2011年8月17日水曜日

Unpopular cargo: Radioactive waste shipload coming

Japan will soon receive its first shipment of highly radioactive waste amid the Fukushima No. 1 nuclear plant triple-meltdown crisis that started in March, and at a time when the storage of such dangerous substances is increasingly problematic.

News photoHot potato: The Pacific Grebe, which set sail from the U.K. on Aug. 3, is Japan-bound with 38 metric tons of highly radioactive waste. INTERNATIONAL NUCLEAR SERVICES LTD. / BLOOMBERG

The freighter Pacific Grebe set sail from Britain on Aug. 3 with more than 30 tons of radioactive waste on board. The cargo, Japanese spent fuel reprocessed in the U.K., is returning sealed in 76 stainless steel canisters packed into 130-ton containers. It is set to arrive early next month at Mutsu-Ogawara port in Aomori Prefecture for delivery to Japan Nuclear Fuel's nearby Rokkasho storage site.

About 400 km south of the port, thousands of workers are struggling to contain radiation leaks, amounting to some 300 tons of atomic waste, from Tokyo Electric Power Co.'s crippled plant.

The Fukushima disaster and the voyage of the Pacific Grebe highlights the dilemma facing Japan and the world's nuclear industry: Radioactive waste is deadly and needs to be locked away for thousands of years, so how can any storage site be guaranteed safe and permanent?

"It's a very big problem with no acceptable solution," said Chris Busby, a visiting professor at the University of Ulster's school of biomedical sciences, who studied Sweden's nuclear waste storage proposals. "And more waste is being produced every year."

The issue ensnared U.S. President Barack Obama in 2009 when he canceled plans to build a permanent repository for nuclear waste at Yucca Mountain in Nevada due to opposition from local residents and politicians. That was after 20 years of work and an investment of $10 billion.

Rokkasho is not designated as a permanent storage site for nuclear waste — despite costing almost ¥3 trillion to build its five facilities on 740 hectares and having 2,450 employees on site. Japan will not have a permanent site operational until the 2040s, according to Yuichiro Akashi, a spokesman for the Nuclear Waste Management Organization of Japan. The group aims to identify a location by 2017, he said. "It's a tough situation considering how long it takes to build one," Akashi said. "A final repository is something we can't do without, so the work will continue."

Radioactive waste meanwhile is piling up and Rokkasho's storage space for spent nuclear fuel is more than 90 percent full; it has capacity for 3,000 tons and contains 2,834 tons, Japan Nuclear Fuel Ltd. spokesman Hirotake Tatehana said.

Rokkasho, 3 km from the Pacific coast, stores two main types of waste: spent fuel from reactors, and what is left over after spent fuel is processed to extract uranium and plutonium for reuse. The latter is what is arriving on the Pacific Grebe.

Japan contracted the U.K. and France to process its fuel in the 1970s and the waste from the procedure is shipped back for storage. The Pacific Grebe cargo is the second of 11 that will return a total of 900 canisters of waste, each weighing about 400 kg. Japan is now building its own spent fuel processing plant at Rokkasho.For waste from processed spent fuel, Rokkasho can hold 2,880 canisters and has reserve capacity for another 3,000, said Tatehana.

Before Fukushima, Japan's 54 reactors produced 1,000 tons of spent fuel a year, which after processing would fill Rokkasho's capacity within four years, according to Bloomberg News calculations.

One ton of spent fuel creates one canister of waste, said Ahn Joon Hong, a professor in the nuclear engineering department at the University of California, Berkeley.

Japan's response to the storage space dilemma for spent fuel is the same as the U.S., which is to keep it in reactor buildings.

The fuel is stored in 13-meter-deep pools of circulating water that cool the uranium rods removed from reactor cores every three years and block release of radiation. The fuel still contains 20 times the amount of radiation that would kill a human if exposed for one hour, according to U.S. regulators.

"Japan has 1,000 tons of spent fuel coming out of reactors every year, and there are seven more years before the spent fuel pools are filled," said Taro Kono, a Liberal Democratic Party lawmaker and opponent of nuclear power.

"(Tepco) is building a facility that will give us another five years, so after 12 years we have no place to put spent fuel," said Kono. "At that point nuclear reactors will be shut because there's no place for the fuel."

Construction of the Tepco storage site in Mutsu, about 40 km north of Rokkasho, has been suspended since the Fukushima crisis started.

In the U.S., 78 percent of the almost 72,000 tons of spent fuel generated during the past four decades is being stored in cooling pools across the country, according to the U.S. Nuclear Regulatory Commission. Another 2,000 tons is added each year, the Institute for Public Policy estimates.

The March 11 earthquake and tsunami showed the vulnerability of spent fuel cooling pools. The tsunami knocked out power, which led to hydrogen explosions that blew the roof off reactor buildings, exposing spent fuel pools as they lost cooling water and leaked radiation. Unlike fuel inside a reactor, the pools have no blast-proof containment.

Loss of water in the spent fuel storage pool at reactor 4 was the biggest risk at the Fukushima plant, NRC chief Gregory Jaczko said March 17.

Reactor pool 4 contained 142 tons of fuel that would burn on exposure to the atmosphere and release radiation, Marvin Resnikoff, a nuclear physicist for Washington-based Physicians for Social Responsibility, said in a telephone press conference the same day.

Moving spent fuel from pools inside reactor buildings will be a priority, the NRC said in a review of the U.S. nuclear industry after Fukushima.

Companies such as closely held Holtec International Corp., based in Jupiter, Florida, may benefit from that decision. It has a process that stores spent fuel in steel and concrete casks that cost as much as $2 million each, according to the NRC. The casks are typically still stored in nuclear power plants.

After the scrapping of the planned Yucca Mountain storage site, Obama set up a commission to find a solution. In a draft report issued July 29, it suggested that communities "volunteer to be considered to host a new nuclear-waste management facility."

In 2007, a town mayor in Shikoku ran for re-election on a plan to host a nuclear waste dump in exchange for about ¥2 trillion in government and corporate subsidies over 60 years. He lost and the plan was rejected.

"The idea that these facilities would be around for thousands of years would not be a popular topic," said Michael Friedlander, who has 13 years of experience running nuclear power plants in the U.S. "The reality of it is until there is an alternative that's what we are looking at."

Japan also faces technological challenges in processing spent fuel. Reprocessing at Rokkasho has been delayed 18 times since 1997 and is now due to start in October next year, according to Japan Nuclear Fuel.

Another proposed solution to the waste problem is the Monju prototype fast-breeder reactor designed to use processed fuel from Rokkasho. That has also experienced an accident and faced repeated delays. In theory, a reactor like Monju would "breed" more fissionable fuel than it consumes and reduce waste. In reality, Monju is not working, the LDP's Kono said.

"Back in 1967 the government was saying that a fast breeder reactor would be ready in 20 years, in the 1970s they said it will take 30 years. What will happen in 2050 is that they'll say it will probably be available in 70 years," he said. "We're not going to have it, and we know it."

Monju's problems have included a fire in 1995 that shut it for 15 years, and in June the atomic energy agency extracted a 3.3-ton fuel-exchange device that had been stuck inside the reactor vessel for about 10 months following a malfunction.

"The Japanese reprocessing and fast breeder program has never made sense from safety, security or economic perspectives," Edwin Lyman, a senior scientist for the global security program at the Union of Concerned Scientists in the U.S., said in an email. "It makes even less sense now after Fukushima."

Elsewhere, the storage search continues. After three decades of research, the Swedish Nuclear Fuel and Waste Management Co. picked the town of Forsmark in March to build a repository that will have corrosion-resistant copper canisters buried 500 meters in crystalline basement rock, isolated from human contact for at least 100,000 years. Its analysis covers "periods as long as 1 million years," according to the company's website.

It is "silly" to assume the waste will not leak from the canisters and pollute the Baltic Sea over such a long period, Ulster University's Busby said.

While building a storage facility takes two to three years and can be done to withstand known tsunami and earthquakes, the dangers of the future cannot be forecast, U.S. nuclear engineer Friedlander said.

Guaranteeing a permanent site is difficult, because no one can prove that it can last thousands of years.

Yet, endless debate on long-term storage does not provide a solution to the nuclear waste that is here and needs to be dealt with, Friedlander said.

"How do you know that that is the strongest earthquake you could ever experience and how do you know that you could provide security for 100,000 years? It turns into an academic discussion. How do you know anything?

"You do the best job you can with the information and materials that you have available to you today. And you just decide that you are going to do it."


View the original article here

0 件のコメント:

コメントを投稿