Crack forces shutdown of North Carolina nuclear reactor

A quarter-inch crack in a reactor sensor at the Shearon Harris nuclear plant in southwest Wake County has forced Duke Energy to take the plant offline, officials said Thursday.

No radioactive material leaked from the plant, and public health and safety is not in danger, spokeswoman Kim Crawford said.

"There are no indications that there was any leakage," Crawford said. "We made the conservative decision to take the unit offline and make the repair."

Crawford said she couldn't say how long the reactor would be out of commission, but she said the utility has plenty of capacity and wouldn't need to purchase electricity from outside sources to meet demand.

"We're not anticipating any issues," she said. "While our plant is offline, we'll continue to serve our customers."

Shearon Harris provides power to about 550,000 customers, and industry sources said not operating the reactor could cost Duke about $1 million a day. Read more >>

Nuclear Nightmare Getting Worse, Yet Propaganda Continues

Image via WikipediaMark Sircus
Japan said it is considering expanding the area covered by a compulsory evacuation order, with no immediate end in sight to the world’s worst nuclear accident since Chernobyl. At this point we should all sit up and take notice of what is happening and what could all so easily happen.

Emergency workers were pumping nitrogen into the quake-damaged Fukushima Daiichi plant to prevent further explosions. Now we hear things are getting so hot inside the destroyed reactor buildings that they cannot approach. On April 6, Reuters reported, “The core at Japan’s Fukushima nuclear reactor has melted through the reactor pressure vessel,” Rep. Edward Markey told a House hearing on the disaster. “I have been informed by the Nuclear Regulatory Commission (NRC) that the core has gotten so hot that part of it has probably melted through the reactor pressure vessel.” America’s NRC said that some of the core of a stricken Japanese reactor had probably leaked from its steel pressure vessel into the bottom of the containment structure, implying that the damage was even worse than previously thought.

Richard Lahey, who was head of safety research for boiling-water reactors at General Electric when the company installed the units at Fukushima, told the Guardian that at least part of the molten core, which includes melted fuel rods and zirconium alloy cladding, seemed to have sunk through the steel “lower head” of the pressure vessel around reactor no. 2. “The indications we have, from the reactor to radiation readings and the materials they are seeing, suggest that the core has melted through the bottom of the pressure vessel in unit two, and at least some of it is down on the floor of the drywell,” Lahey said.

On April 5, Times writers James Glanz and William Broad headlined, “U.S. Sees Array of New Threats at Japan’s Nuclear Plant,” saying: American engineers warned “that the troubled nuclear plant… is facing a wide array of fresh threats that could persist indefinitely, and that in some cases are expected to increase as a result of the very measures being taken to keep the plant stable,” according to a confidential NRC assessment.

According to former GE reactor designer Margaret Harding, “Exposed/unprotected spent fuel rods in Units 1, 2, 3 and 4 pose extreme dangers. Moreover, explosions blew nuclear material ‘up to one mile from the units’ into the atmosphere, indicating much greater damage than previously disclosed. As a result, David Lochbaum from the Union of Concerned Scientists (UCS) believes, “This paints a very different picture, and suggests that things are a lot worse. They could still have more damage in a big way if some of these things don’t work out for them… They’ve got a lot of nasty things to (handle), and one missed step could make the situation much, much worse.”

On March 29, Dr. Chris Busby said, “In fact, Fukushima already way exceeds Chernobyl and Three Mile Island and will get increasingly worse ahead as radiation releases continue and spread. I believe that (the array of) phony experts are criminally irresponsible, since their advice will lead to millions of deaths… I hope they are sent to jail where they can have plenty of time to read the scientific proofs (showing) their advice was based on the mathematical analysis of thin air.”

Dr. Busby cited John Gofman, a senior U.S. Atomic Energy Commission expert who resigned, saying: “The nuclear industry is waging a war against humanity.” Busby calls it “the greatest public health scandal in human history,” which can be witnessed in the present as the government and press continue to mislead the public. More...

U.S. Helicopters in Japan detects radiation presumed to include Cesium-137 and Iodine-121 — suggesting widening environmental contamination

Image via WikipediaBy DAVID E. SANGER and MATTHEW L. WALD
NYTIMES
As the scale of Japan’s nuclear crisis begins to come to light, experts in Japan and the United States say the country is now facing a cascade of accumulating problems that suggest that radioactive releases of steam from the crippled plants could go on for weeks or even months.

The emergency flooding of two stricken reactors with seawater and the resulting steam releases are a desperate step intended to avoid a much bigger problem: a full meltdown of the nuclear cores in two reactors at the Fukushima Daiichi Nuclear Power Station. So far, Japanese officials have said the melting of the nuclear cores in the two plants is assumed to be “partial,” and the amount of radioactivity measured outside the plants, though twice the level Japan considers safe, has been relatively modest.

But Pentagon officials reported Sunday that helicopters flying 60 miles from the plant picked up small amounts of radioactive particulates — still being analyzed, but presumed to include Cesium-137 and Iodine-121 — suggesting widening environmental contamination. In a country where memories of a nuclear horror of a different sort in the last days of World War II weigh heavily on the national psyche and national politics, the impact of continued venting of long-lasting radioactivity from the plants is hard to overstate.

Japanese reactor operators now have little choice but to periodically release radioactive steam until the radioactive elements in the fuel of the stricken reactors stop generating intense heat, a process that can continue for a year or more even after the fission process has stopped. To control that heat, the plant’s operator must constantly try to flood the reactors with seawater, then release the resulting radioactive steam into the atmosphere, several experts familiar with the design of the Daiichi facility said. That suggests that the 200,000 people who have been evacuated may not be able to return to their homes for a considerable period and that shifts in the wind could blow radioactive materials toward Japanese cities rather than out to sea.

Re-establishing normal cooling of the reactors would require restoring electric power — which was cut in the earthquake and tsunami — and now may require plant technicians working in areas that have become highly contaminated with radioactivity.

More steam releases also mean that the plume headed across the Pacific could continue to grow. On Sunday evening, the White House sought to tamp down concerns, saying that modeling done by the Nuclear Regulatory Commission had concluded that “Hawaii, Alaska, the U.S. Territories and the U.S. West Coast are not expected to experience any harmful levels of radioactivity.”

But all weekend, after a series of intense interchanges between Tokyo and Washington and the arrival of the first American nuclear experts in Japan, officials said they were beginning to get a clearer picture of what went wrong over the past three days, and as one senior official put it, “under the best scenarios, this isn’t going to end anytime soon.”

The essential problem is the definition of “off” in a nuclear reactor. When the nuclear chain reaction is shut and the reactor shuts down, the fuel is still producing about 6 percent as much heat as it did when it was running, because of continuing heat generation by the radioactivity, the release of subatomic particles and of gamma rays.

Usually, when a reactor is first shut down, an electrically driven pump pulls heated water from the vessel to a heat exchanger, and cool water from a river or ocean is brought in to draw off that heat.

But at the Japanese reactors, after losing electric power, that system could not be used. Instead the operators are dumping seawater into the vessel, and letting it cool the fuel by boiling. But as it boils, pressure rises too high to pump in more water, so they have to vent the vessel to the atmosphere, and feed in more water, a procedure known as “feed and bleed.”

When the fuel was intact, the steam they were releasing had only modest amounts of radioactive material, in a nontroublesome form. With damaged fuel, that steam is getting dirtier.

Re-establishing normal cooling will require electric power and may require workers to function in areas that are now contaminated, American nuclear experts say. More...