Q+A: What do latest events at Japan nuclear power plant mean? Posted by Meosha Eaton

By Elaine Lies

March 16 (Reuters) - Japan's nuclear crisis worsened on Wednesday, with workers ordered to withdraw briefly from the stricken power plant after radiation levels spiked, just hours after smoke was seen rising from the quake-crippled nuclear facility.


Q: What does the smoke mean?

A: The smoke is most likely to be steam, a natural byproduct of pouring water into the reactors to cool them down and keep the fuel rods covered. Authorities are also trying to maintain water levels at a spent-fuel storage pool at the plant's No. 4 reactor, which experts now view as the real threat.

The steam is an issue because it contains radioactive particles, but experts say these particles may not be as serious as, say, an explosion within a reactor core. So far, it appears the radiation is mostly escaping in the form of steam and some experts believe the radioactive particles could merely be dust or from rusted structures within the reactor buildings -- known as "crud" within the nuclear industry. Radiation levels have not risen significantly in Tokyo, about 240 km to the south.


Q: Why is the situation at the spent-fuel pool a worry?

A: Unlike the reactors themselves, which are inside two containers -- a massive steel container as well as one made of concrete -- the fuel pools are not, with meters of water on top of the rods providing safety only under normal circumstances. Another concern with reactor No. 4 is that the water levels in the pool could be falling, perhaps because the water is or has been boiling and is evaporating as steam.

While nobody knows exactly how much damage Tuesday's explosion did to the building, the structure does have holes and some experts have said that proposals to drop boric acid particles on the reactor suggest substantial holes in the roof.

"That's got to be protected. I'd hate to see another explosion there," said Murray Jennex, a professor at San Diego State University in California.


Q: What can be done?

A: Dropping boric acid could be helpful since it is both a fire suppressant and also absorbs radiation, while keeping water levels up in the pool is also essential. Finally, a fresh crew of workers should be sent into the plant since those who are in there are likely exhausted and may be making poor decisions, which could be adding to problems.


Q: What about the spent-fuel pools at the other reactors?

A: There are six reactors at the Daiichi complex. Three of them - no. 4 through No.6 - were offline for maintenance at the time of the quake. There are signs that water temperatures are also rising at No.5 and No.6 spent-fuel pools.

But the spent fuel at these two pools, as well as at the three reactors that were online at the time of the quake, is all older and thus less likely to pose an overheating threat.


Q: What about the other reactors?

A: There have been explosions at reactors No.1, No.2 and No.3, and suspicions that the suppression pool at No. 2 may have been damaged. But experts say that current low radiation levels suggest that the container vessels at these reactors are by and large holding, and that they're actually more optimistic about this situation than they were on Tuesday.

Doubt does remain about possible damage to the suppression pool at No. 2, but these are "overdesigned" to cope with a certain amount of damage.


Q: What do we need to watch out for?

A: Steadily rising radiation levels are the main worry, along with a fall in the water level in the spent fuel pool. Radiation levels at the plant's main gate spiked on Wednesday morning but have since fallen back, which is a good sign.

"If we have the water level doing down and rising radiation, that's a bad sign, because this means more and more of this fuel (is) exposed," said Najm Meshati, professor of civil and environmental engineering, at the University of Southern California at Los Angeles.

(Editing by Mark Bendeich

* Tsunami reaches more than 6 feet in California, Posted by Meosha Eaton

* Tsunami reaches more than 6 feet in California
* Thousands evacuate in California
* Hawaii residents told to move inland
* Ecuador takes extreme precautions

(Updates with Ecuador, Mexico tsunami preparations)

By Peter Henderson and Alexandra Valencia
OAKLAND, Calif./QUITO, March 11 (Reuters) - Thousands of people fled their homes along the California coast on Friday as a tsunami triggered by the massive earthquake in Japan began hitting the U.S. West Coast after rolling through Hawaii.

Initial reports from U.S. civil defense officials and residents of coastal communities suggested the force of the tsunami, a giant wall of water, had dissipated as it sped across the Pacific Ocean toward North America. The massive 8.9 magnitude quake in Japan triggered tsunami warnings for most of the Pacific basin. Advisories or warnings were in effect from Canada all the way down the Pacific coast of South America.

Tidal surges in the Hawaiian island chain were generally little higher than normal, officials said, and there were no reports of injuries or severe inland property damage.
An Obama administration official said Hawaii appeared to be out of danger, but some risk remained for the U.S. West Coast.

"I think the enormous fears that were there hours ago, for some of us hours ago, has diminished greatly, which is quite a relief for all of us," White House chief of staff Bill Daley said. "There's always the possibility that something may happen after, so people are watching it now," he added.

Craig Fugate, administrator of the Federal Emergency Management Agency, was more cautious. "The problem is you're never sure until the waves come in," he told CNN.
Tsunami waves crashing ashore in the northern Californian city of Crescent City were more than 6 feet (2 metres), the Pacific Tsunami Warning Center said.

"They are starting to roll in," said Jordan Scott, spokesman for the California Emergency Management Agency. He cautioned it could take 10 to 12 hours for the effects of the quake to completely fade.

Thousands of residents were being evacuated along the California coast, including some 6,000 near the surfing town of Santa Cruz, civil defense officials said.
Scott said people were also being evacuated in Del Norte and San Mateo counties. Del Norte is the northernmost California coastal county and San Mateo includes much of Silicon Valley, although the technology center is well inland. Authorities in the neighboring state of Oregon closed schools along the coast and advised residents to evacuate.

SIRENS BLARE IN HAWAII
In Hawaii, 3,800 miles (6,200 km) from Japan, the main airports on at least three of the major islands -- Maui, Kauai and the Big Island of Hawaii -- were shut down as a precaution, and the U.S. Navy ordered all warships in Pearl Harbor to remain in port to support rescue missions as needed. Civil defense sirens blared statewide, starting shortly before 10 p.m. local time, and police with bullhorns urged residents near shore to higher ground.

John Cummings, a spokesman for emergency management in Honolulu, said no injuries or property damage had been reported after a series of four tsunami waves had hit the Hawaii's capital or the rest of the island of Oahu. President Barack Obama, a native of Hawaii, was notified of the massive Japanese quake at 4 a.m./0900 GMT and instructed FEMA to be prepared to help affected U.S. states and territories, the White House said.

CHILE RESIDENTS ALERT
Ecuador took extreme precautions after President Rafael Correa declared a state of emergency across the Andean nation on national television and urged residents to move inland.

The area at risk includes the Galapagos Islands -- a popular tourist destination known for its incredible wildlife, including endangered species, that inspired British naturalist Charles Darwin's evolution theory in the 19th century. State oil company Petroecuador halted product shipments.

On Easter Island, a Chilean territory in the South Pacific, authorities planned to move residents to higher ground, in preparation for a possible tsunami on Friday afternoon.
Chilean President Sebastian Pinera, whose country was hit by a 8.8 magnitude quake and ensuing tsunamis that killed more than 500 people a year ago, told Chileans to remain alert. Peruvian officials said they were waiting until late afternoon to decide if they would order evacuations from low-lying coastal areas such as the port city of Callao.

Many ports along Mexico's western coast were closed, including Los Cabos and Salina Cruz in southern Oaxaca, the only oil-exporting terminal on the country's Pacific side.
State-run oil company Pemex's biggest refinery, Antonio Dovali Jaime, is about two miles (3 km) from the coast near Salina Cruz but a spokesman said operations were normal. Canada advised authorities in parts of British Columbia to evacuate marinas, beaches and other low-lying areas.

(Additional reporting by Suzanne Roig and Jorene Barut in Honolulu, Peter Henderson in San Francisco, Steve Gorman in Los Angeles, Simon Gardner in Santiago; Anahi Rama, Cyntia Barrera Diaz, Mica Rosenberg and Lizbeth Diaz in Mexico; writing by Frances Kerry and Ross Colvin; Editing by Doina Chiacu)