National Park Service via AP file

A deactivated nuclear launch facility near Wall, S.D., similar to classified facilities at Minot (N.D.) Air Force Base. All 17 of the AirForce officers disciplined last month are assigned to Minot.

A "breakdown in overall discipline" led the Air Force to suspend 17 officers and disqualify them from controlling nuclear missiles after a poor inspection at one of the service's most important nuclear bases, military officials told NBC News on Wednesday.

All 17 officers are assigned to 91st Missile Wing at Minot Air Force Base in North Dakota, headquarters of the 5th Bomb Wing, which maintains 150 nuclear-tipped Minuteman intercontinental ballistic missiles.

The unit received a "D" rating during inspections in March, leading senior officials at the base to call for an immediate crackdown, NBC station KMOT of Minot reported.

The inspection was only the latest in a series of high-profile failings, which led the group's deputy commander, Lt. Col. Jay Folds, to send an internal email complaining that the unit is suffering "rot" within its ranks, according to a copy obtained by The Associated Press.

"We are, in fact, in a crisis right now," Folds wrote, according to the AP.

The 17 officers — representing almost 5 percent of the 91st Missile Wing's missile launch staff — were suspended for 60 days last month and were stripped of their authority to control and launch nuclear missiles after the "D," or "marginal," inspection in March, an inspection the Air Force publicly labeled a success.

Air Force and other Defense Department officials confirmed the basic details of the AP report, telling NBC News that a "breakdown in overall discipline" led to a series of relatively minor violations of rules and procedures.

The base's nuclear weapons and facilities were never in jeopardy, they said. But the combined potential impact of the violations raised serious concern within the base's leadership, they confirmed.

The base has come under scrutiny for other incidents in recent years that raised questions about its security and oversight.

In August 2007, six cruise missiles loaded with W80-1 nuclear warheads were flown from Minot to Barksdale Air Force Base in Louisiana before authorities discovered that the warheads hadn't been removed for safety, as required.

In a review of the incident in February 2008 (.pdf), the Defense Advisory Board blamed "process and systemic problems" that had "developed over more than a decade and have the potential for much more serious consequences."

But just five months after the blistering report was issued, in July 2008, three Air Force officers fell asleep at the controls of a component that contained old launch codes for nuclear ICBMs. They were immediately barred from working with classified and nuclear materials and were later discharged from the service.

The new report comes as the base is breaking in a new commander, Col. Alexis Mezynski, who took over in January and must now work to put out the fire.

In an interview with KMOT as he assumed command in January, Mezynski acknowledged that there were problems at the base, which was built in the 1950s and needs to be brought back up "to conditions that are workable."

"There are going to be changes," he promised at the time.

Jim Miklaszewski and Courtney Kube of NBC News contributed to this report. Follow M. Alex Johnson on Twitter and Facebook.

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Getty Images photo

A Trident II nuclear missile is shown in an undated file photo.

Senior Obama administration officials have agreed that the number of nuclear warheads the U.S. military deploys could be cut by at least a third without harming national security, according to sources involved in the deliberations.

They said the officials’ consensus agreement, not yet announced, opens the door to billions of dollars in military savings that might ease the federal deficit. It might also improve prospects for a new arms deal with Russia before the president leaves office, the sources said, but is likely to draw fire from conservatives, if previous debate on the issue is any guide.

The results of the internal review are reflected in a draft of a classified decision directive prepared for Obama’s signature that guides how U.S. nuclear weapons should be targeted against potential foes, according to four sources with direct knowledge of it. The sources, who requested anonymity because they were not authorized to talk to a reporter about the review, described the president as fully on board, but said he has not signed the document.

The document directs the first detailed Pentagon revisions in U.S. targeting since 2009, when the military’s nuclear war planners last took account of a substantial shrinkage -- roughly by half from 2000 to 2008 -- in the total number of nuclear weapons in the U.S. arsenal. It makes clear that an even smaller nuclear force can still meet all defense requirements.

Although the document offers various options for Obama, his top advisers reached their consensus position last year, after a review that included the State Department, the Defense Department, the National Security Council, the intelligence community, the U.S. Strategic Command, the Joint Chiefs of Staff and the office of Vice President Joseph Biden, according to the sources.

Several said the results were not disclosed at the time partly because of political concerns that any resulting controversy might rob Obama of popular votes in the November election. Some Republican lawmakers have said they oppose cutting the U.S. arsenal out of concern that it could diminish America’s standing in the world.

The new policy directive, which would formally implement a revised nuclear policy Obama adopted in 2010, endorses the use of a smaller U.S. arsenal to deter attacks or protect American interests by targeting fewer, but more important, military or political sites in Russia, China and several other countries. This can be accomplished by 1,000-1,100 warheads, the sources said, instead of the 1,550 allowed under an existing arms treaty.

The 2010 policy called for reducing the role of nuclear weapons, arguing that they are “poorly suited to address the challenges posed by suicidal terrorists and unfriendly regimes seeking nuclear weapons.” But many critics have charged that not much of the policy has been implemented. Obama himself even joked in a video message to the Jan. 26 annual dinner of Washington’s exclusive Alfalfa Club, that he could not recall why he won his 2009 Nobel Peace Prize [the Oslo committee attributed it partly to his stimulation of “disarmament and arms control negotiations”].

With the election behind him and a new national security team selected, Obama is finally prepared to send this new guidance to the Joint Chiefs of Staff and to open a new dialogue with Russia about corresponding reductions in deployed weapons beyond those called for in a 2011 treaty, according to two senior U.S. officials involved in the deliberations.

“It is all done,” said one. “We did so much work on it that there is no interest in going back and taking another look at it.” The second official said completion of the new directive would become public in coming weeks, when Obama may mention the issue in his State of the Union address on Feb. 12, or in another speech specifically dedicated to the subject, similar to the April 2009 Prague address in which he promised to “take concrete steps towards a world without nuclear weapons.”

Arms talks now being explored
While the draft directive opens the door to scrapping a substantial portion of the U.S. arsenal, it does not order those reductions immediately or suggest they be undertaken unilaterally, the officials said. Instead, the administration’s ambition is to negotiate an addendum of sorts to its 2010 New Start treaty with Russia, in the form of a legally binding agreement or an informal understanding. Officials said the latter path could be chosen if gaining the assent of two-thirds of the Senate to a treaty is not possible.

Preliminary discussions about this ambition occurred in Munich on Feb. 2 between Vice President Joe Biden and Russian Foreign Minister Sergei Lavrov, and additional talks are slated in Moscow this month with acting undersecretary of state Rose Gottemoeller and White House national security adviser Thomas Donilon. Obama “believes that there’s room to explore the potential for continued reductions, and that, of course, the best way to do so is in a discussion with Russia,” deputy national security adviser Ben Rhodes said on Jan. 31.

White House spokesman Tommy Vietor declined comment on Feb. 6 on the draft directive.

The New Start treaty limits each side to deploying no more than 1,550 strategic nuclear weapons by 2018, but uses a counting rule that pretends strategic bombers carry only a single warhead, instead of up to 20. So the actual arsenals after the treaty takes effect are likely to be closer to 1,900, a number that Obama’s advisers now think is too high.

New Start also imposes no limits on nuclear weapons in each country that are held in storage or considered of “tactical” or short-range use -- a number estimated by independent experts as roughly 2,700 in the United States and 2,680 in Russia. Under the new deal envisioned by the administration, Russia and the United States would agree not only to cut deployed warhead levels below 1,550 to around 1,000 to 1,100 but also -- for the first time -- begin to constrain the size of these additional categories.

Several officials said that as a result, the total number of nuclear warheads could shrink to less than 3,500 and perhaps as low as 2,500, or a bit more than half the present U.S. arsenal, without harming security or requiring a major reconfiguration of existing missiles or bombers.

A much steeper reduction, to around 500 total warheads, was debated within the administration last year, but rejected, the officials said. Known as the “deterrence only” plan, it would have aimed U.S. warheads at a narrower range of targets related to the enemy’s economic capacity and no longer emphasized striking the enemy’s leadership and weaponry in the first wave of an attack.

Nuclear weapons experts have long considered the latter “warfighting” goal destabilizing because it arouses fears among all the combatants of a decapitating, preemptive strike that could obstruct a significant retaliation, but it has been a salient feature of the U.S. nuclear policy for half a century. China, in contrast, has adopted a “deterrence-only” strategy, keeping only a minimal arsenal of missiles aimed partly at targets in or near large cities.

Some officials at the State Department, the NSC staff, and Biden’s staff urged consideration of the smaller arsenal and new targeting policy, officials said. But “a small brake” was applied by the Joint Chiefs of Staff chairman, Army Gen. Martin E. Dempsey, who worried that making such a major policy change was too risky at a moment of upheaval in conventional military strategy, and would create too much uncertainty among allies.

Obama, who followed the deliberations intermittently, “decided we did not need to do deterrence-only targeting now,” but did not rule it out, one of the sources with knowledge of the discussions said.

Air Force Lt. Gen. James Kowalski, who as head of the Global Strike Command oversees the operations of bombers and land-based missiles capable of carrying more than a thousand nuclear warheads to foreign targets, said at a breakfast with reporters on Feb. 6 that if asked, “can you go below 1500” treaty-accountable weapons, his response is, “Yeah, I think there is some headroom in there.” But he warned that shrinking the force to well below 1,000 would require “major structural changes in how we do this business.”

Additional cuts would save billions of dollars
The financial savings from even the modest reduction now being contemplated could be substantial, according to officials and independent experts. Already, to comply with New Start, the Pentagon has been pulling warheads from land-based missiles and making plans to decommission some of the missiles themselves; it is also planning to reduce the number of missile tubes aboard its Trident submarines.

By pushing the arsenal size even lower, it could close perhaps two of its three land-based missile wings and cut at least two of the 12 new strategic submarines it now plans to build – saving $6 billion to $8 billion for each one. Eliminating a single wing of 150 missiles would save roughly $360 million a year, or $3 billion over a decade, according to Tom Collina, research director at the Arms Control Association, a nonprofit research group in Washington. Modernization of the land-based missiles might also be deferred, bringing additional savings.

Russia, meanwhile, has been  phasing out three older missile types that loomed large during Cold War tensions – the SS-18, the SS-19, and the SS-25 – and is replacing them with a more modern missile, the SS-27, in three forms. It is also planning to build a costly, larger missile, capable of carrying multiple warheads. Pentagon officials are not alarmed by that possibility, but say that a new arms deal could give Russia reason to scale back its own spending.

“The Russian Federation … would not be able to achieve a militarily significant advantage by any plausible expansion of its strategic nuclear forces, even in a cheating or breakout scenario” because it cannot destroy U.S. missile-carrying submarines at sea, the Defense Department said in a May 2012 classified report to Congress, partially declassified and released last month to the Federation of American Scientists (FAS).

Related: Hagel's nuclear abolition endorsement spurs GOP questions on deterrence

Three participants in the targeting policy review said Russia nonetheless remains the sole U.S. target that still requires potential use of a large number of nuclear warheads to achieve damage that military planners deem adequate, even though Obama famously said last September at the Democratic National Convention that “you don't call Russia our number one enemy — not al-Qaeda, Russia — (laughter) — unless you're still stuck in a Cold War mind warp.”

U.S. nuclear targets include China, North Korea, and Iran, officials have said. But the list of predictable enemies has been steadily shrinking: Iraq was once on the list – as recently as 1997, the Defense Department studied radioactive fallout distribution patterns from a potential U.S. attack there – but it now poses no threats, and Syria – another perennial listee – is in the midst of imploding and unable even to muster a response to Israel’s recent bombing of an arms factory in its capital.

Russian arms reductions taken to date make U.S. targeting revisions feasible now, according to Hans Kristensen, a nuclear arms expert at FAS. A decade ago, the U.S. military was targeting 660 Russian missile silos with multiple warheads, he said; now, the number of such silos is less than half that, and in a decade, it is unlikely to exceed 230. Several officials also pointed out that Russia currently fields a smaller and weaker conventional military force than it once did, also allowing U.S. targeting to be scaled back.

Obama’s new appointees are on board
Key members of Obama’s new national security team are on board with the reduction strategy.

“There's talk of going down to a lower number,” Secretary of State John F. Kerry said during his confirmation hearing on Jan. 24. “I think, personally, it's possible to get there if you have commensurate levels of -- of inspections, verification, guarantees about the capacity of your nuclear stockpile program, et cetera.”

Secretary of Defense nominee Chuck Hagel drew fire from Republicans at his Jan. 31 confirmation hearing for signing a report last summer that said current stockpiles “vastly exceed what is needed to satisfy reasonable requirements of deterrence” and that nuclear weapons are arguably “more a part of the problem than any solution.”  An appropriately modernized force, the Global Zero report said, would consist of just 900 total strategic weapons on each side, not 5000, and get rid of land-based missiles subject to accidental or unauthorized launch.

Sen. Jeff Sessions (R-Ala.) told Hagel that cuts of that magnitude would “create instability, rather than confidence and stability; create uncertainty in the world among our allies and our potential adversaries.” He said the current U.S. arsenal projects “an image of solidity and -- and steadfastness” to citizens around the globe.

Hagel responded at the hearing that the report simply provided illustrative scenarios, not recommendations. But he affirmed the report’s conclusion that “we have to look at” the value and cost of continuing to keep land-based missiles and made no promise to build all 12 new missile-carrying submarines sought by the Navy.

The United States is not the only nuclear weapons state considering a retrenchment. A senior British treasury official told the London Guardian several weeks ago that given fiscal pressures in London, the country needs a wide debate “over the approach we take to nuclear deterrence” and should consider scaling back either its purchase or deployment of costly new nuclear missile-carrying submarines. Michael Portillo, the defense minister under Conservative Prime Minister John Major in the 1990s, told the Financial Times last month that Britain maintained its arsenal “partly for industrial and employment reasons, and mainly for prestige.” He called it “a tremendous waste of money.”

UN Secretary General Ban Ki-Moon is among those urging a major shift. In a speech last month in California, he called for all nuclear-armed states to “reconsider their national nuclear posture,” and said the United States and Russia had a special obligation to undertake deeper cuts. “Nuclear disarmament is off-track,” he said. “Delay comes with a high price tag. The longer we procrastinate, the greater the risk that these weapons will be used, will proliferate or be acquired by terrorists.”

Some senior U.S.  officials are skeptical that Russian president Vladimir Putin would agree to a new treaty, because his government claims to depend more heavily than Americans on nuclear arms for security; others worry that Republican opposition in the Senate may obstruct ratification of any new treaty.  But there remains high interest, officials said, in at least exploring a new joint, lower limit.

The Center for Public Integrity is a non-profit, independent investigative news outlet. For more of its stories on this topic go to publicintegrity.org.

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Mark Ralston / AFP - Getty Images

A view of the San Onofre Nuclear Power Plant in north San Diego County is seen in this March 2011 file photo.

The operator of California's troubled San Onofre nuclear power plant proposed Thursday to restart one of the plant's shuttered  reactors, despite an outcry from activists who say doing so could be catastrophic.

Southern California Edison filed the proposal with the Nuclear Regulatory Commission after concluding a reactor could be operated safely despite damage to scores of its tubes that carry radioactive water.

A plan to return even one reactor to service is a milestone for Southern California Edison, which has spent months unraveling what caused excessive tube vibration and friction inside the plant's nearly new steam generators, then determining how it might be fixed.

But the plant is far from returning to robust operation.

Edison must wait for approval from U.S. nuclear regulators before restarting the unit. Nuclear regulators say there's no timetable to restart the plant, and review of the application could take months. "The agency will not permit a restart unless and until we can conclude the reactor can be operated safely," NRC Chairman Allison Macfarlane told Reuters. "Our inspections and review will be painstaking, thorough and will not be rushed."

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The proposal was immediately denounced by environmentalists and anti-nuclear activists who have argued for months that restarting the plant between San Diego and Los Angeles would set the stage for a catastrophe. About 7.4 million Californians live within 50 miles of San Onofre, which can power 1.4 million homes.

"Both these reactors are alike, and neither is safe to operate," said S. David Freeman, a former head of the Los Angeles Department of Water and Power who advises Friends of the Earth. "While Edison may be under financial pressure to get one up and running, operating this badly damaged reactor at reduced power without fixing or replacing these leaky generators is like driving a car with worn-out brakes."

Edison wants to operate Unit 2 at 70 percent power, which company officials predicted would prevent vibration that has caused excessive wear to tubing. Company officials expressed confidence in the proposal, which followed more than 170,000 tube inspections over more than eight months.

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In January, the Unit 3 reactor was shut down as a precaution after a tube leak. Unit 2 was taken offline earlier that month. Neither unit has been operational since. The plant's Unit 1 was shut down permanently in 1992.

Federal regulators examined the plant to determine what happened to Unit 3 and how it could have been prevented. While the Nuclear Regulatory Commission commended the staff for their handling of the leak, they expressed concern over the design flaw that caused it.

Southern California Edison also pointed to the high costs of running the plant as a reason for downsizing its staff. Compared to similar plants, the staffing and costs are much higher. The company will also reduce costs by “improving plant processes while fully maintaining all safety commitments,” they stated in August.

This article includes reporting by NBCLosAngeles.com's Lauren Steussy and Reuters.

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WASHINGTON -- A federal grand jury has indicted two men, one from Iran and the other from China, on charges of conspiring to send materials from the United States to Iran for the purpose of enriching uranium, the U.S. Justice Department said on Friday.

Using a Chinese company as a go-between to avoid trade sanctions, the men tried for three years to obtain U.S. materials, such as high-strength steel, that could be used in an Iranian nuclear program, the department said.

Iranian citizen Parviz Khaki was arrested in May in the Philippines, while the other man, Zongcheng Yi of China, remains at large, the department said.

The two men succeeded in illegally exporting lathes and nickel-alloy wire from the United States to China and then to Iran around June 2009, according to the indictment filed by the Justice Department.

It said the men purchased the materials from U.S. companies without divulging the ultimate destination. They also did not have export licenses required for shipments to countries such as Iran that are under U.S. sanctions.

Other attempts to obtain materials failed, the indictment says.

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Khaki allegedly began talking with an undercover U.S. federal agent in 2009, including in e-mails in which he tried to acquire radioactive source material. The e-mails continued into 2011, the indictment says.

Lisa Monaco, assistant attorney general for national security, said the indictment "sheds light on the reach of Iran's illegal procurement networks and the importance of keeping U.S. nuclear-related materials from being exploited by Iran."

"Iranian procurement networks continue to target U.S. and Western companies for technology acquisition by using fraud, front companies and middlemen in nations around the globe," Monaco said in a statement.

The 24-page indictment was handed up by a grand jury in Washington on Thursday and released on Friday. It does not name the U.S. companies that Khaki and Yi allegedly approached.

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Nuclear Regulatory Commission

Most spent nuclear fuel is stored in pools like this one, with rods typically under 30 feet of water.

In a blow to the nuclear energy industry, a federal appeals court on Friday threw out a rule allowing plants to store spent nuclear fuel onsite for decades after they've closed, and ordered regulators to study the risks involved with that storage -- 65,000 tons now spread across the country, and growing at 2,000 tons a year. 

The Nuclear Regulatory Commission "apparently has no long-term plan other than hoping for a geologic repository," the unanimous ruling stated. "If the government continues to fail in its quest to establish one, then SNF (spent nuclear fuel) will seemingly be stored on site at nuclear plants on a permanent basis. The Commission can and must assess the potential environmental effects of such a failure."

Nuclear plants have been storing spent fuel onsite for decades and the NRC recently said, barring a repository, they may continue to do so even after they shut down.

That regulation was challenged by New York and other Northeast states, as well as environmentalists.

The New York attorney general's office said the ruling means the NRC cannot license or relicense any nuclear power plant until it examines those risks.

That process could take a couple of years, Geoff Fettus, an attorney who argued in court on behalf of the Natural Resources Defense Council, told msnbc.com.

"This is a game changer," he said. "The opinion is quite clear that the agency must comply with the National Environmental Policy Act and do a substantive, searching environmental review of well established legal standards."

The Nuclear Energy Institute, which represents the industry, said it was disappointed with the ruling but urged the NRC to "act expeditiously to undertake the additional environmental analysis."

In recent years, the industry had hoped for a "nuclear renaissance" based on smaller reactors with fewer mechanical parts and less nuclear waste. But Japan's Fukushima nuclear disaster last year was a major setback in building public support.

Nuclear plant operators have been paying $750 million a year to the Energy Department for construction of a central repository. It was being built under Nevada's Yucca Mountain, but engineering issues and a political backlash in Nevada killed the project after $12 billion was spent.

In January, a panel commissioned by President Barack Obama reported that a first step must be to find a site that isn't forced on a particular region by the federal government.

"The need for a new strategy is urgent," the panel wrote in its report, "not just to address these damages and costs but because this generation has a fundamental, ethical obligation to avoid burdening future generations with the entire task of finding a safe, permanent solution for managing hazardous nuclear materials they had no part in creating."

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A fire that broke out Wednesday evening on a U.S. Navy nuclear-powered submarine docked at the Portsmouth Naval Shipyard in Maine injured at least seven people but there were no deaths, a Navy spokesman said on Thursday.

Damage from the fire, which began shortly before 6 p.m. on the USS Miami, an attack submarine docked at the Kittery, Maine, shipyard, was limited to the forward compartment spaces, which include living as well as command and control spaces, Rear Admiral Rick Breckenridge said in a statement.

The submarine was undergoing maintenance.

Breckenridge, who is in charge of submarines in the region, said the ship's nuclear reactor has been shut down for more than two months and remained in safe and stable condition throughout the event. There were no weapons on board in the torpedo room, he said.

The cause of the fire has not yet been identified, Breckenridge said. A full investigation is taking place.

The fire spread to spaces within the submarine that were difficult to reach, Breckenridge said, making it challenging for firefighters to battle the blaze. The fire was brought under control by Portsmouth Naval Shipyard's department, along with several area fire departments. It took hours for the blaze to be extinguished.

The injured personnel included three Portsmouth Naval Shipyard firefighters, two crew members and two civilian firefighters providing support. They were either treated on scene or taken to a local medical facility. All have been released.

The submarine, whose home port is Groton, Conn., arrived at the shipyard in March. It is worth about $600 million, typically carries a crew of 13 officers and 120 enlisted personnel, and is armed with Tomahawk missiles.

Reuters contributed to this report.

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Diablo Canyon Power Plant / AP

This photo provided by the Diablo Canyon Power Plant on Friday shows salp, a gelatinous sea creature, at a nuclear reactor intake structure.

In Japan, it was a monstrous earthquake and tsunami that brought down the Fukushima nuclear plant. In California, it’s a tiny, jellyfish-like sea creature called salp that’s causing problems at the Diablo Canyon atomic plant.

An invasion of salp has prompted Pacific Gas and Electric Co. to temporarily shut down a nuclear reactor at Diablo Canyon, in Avila Beach, San Luisa Obispo County, on the central California coast.

A giant swarm of the transluscent barrel-shaped organisms this week clogged intake screens that are used to keep marine life out of the seawater that is used as a coolant for the nuclear plant.

On Wednesday, PG&E officials reduced power output at the Unit 2 reactor, then decided to shut it down altogether “until conditions improve at the intake structure.” The plant’s other reactor, Unit 1, had already been shut down earlier in the week for a planned refueling and maintenance outage.

“Safety being the number one priority, there was such an influx of salp and you need ocean water to cool the reactors,” PG&E spokesman Tom Cuddy told msnbc.com on Friday. “At that point we made a conservative decision to safely shut down the unit.”

PG&E owns and operates the Diablo Canyon Power Plant, whose two reactors together produce approximately 2,300 net megawatts of electricity – enough to serve nearly 3 million northern and central California homes.

Cuddy said he wasn’t sure when the Unit 1 reactor would come back online.

“We’ll turn the unit on to full power when it’s safe to do so – when the salps leave,” he said. “The bottom line is we’re taking a methodical and conservative approach.”

Lara Uselding, a spokeswoman for the Nuclear Regulatory Commission, the federal agency that oversees reactor safety and security, said the plant is not in any danger.

“It’s not a normal operation condition, but the plant is safe and all the systems operated as designed,” she said.

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Salps are tiny, gelatinous organisms that move by contracting, thus pumping water throughout their bodies. They can reproduce and multiply quickly.

Though salps look a bit like jellyfish, they are actually more closely related to organisms that have backbones. They typically grow to 1 or 2 inches long and usually do not appear at the coast, says Larry Madin, a salp expert and research director at Woods Hole Oceanographic Institution in Massachusetts.

“They’re typically more of an offshore living organism," Madin says. He surmises that the swarm at Diablo may have been carried in on currents blown by wind.

But Steve Haddock, a scientist with the Monterey Bay Aquarium Research Institute in Moss Landing, Calif., said salps have been blooming in high numbers along the California coast since at least December. Several sightings have been reported to JellyWatch, a website Haddock runs to track sightings of jellyfish and other marine organisms.

Other than clogging the cooling system filters of a nuclear plant, the organisms pose no danger, says Bruce Robison, senior scientist at the Monterey Bay Aquarium Research Institute. They don’t sting, they don’t have teeth and they’re not poisonous.

Salps passively feed off tiny organic particles in the water and can reproduce sexually or asexually. “They can have their population size expand tremendously within a short period of time, which makes them very abundant. In a small space, they can take up all the space,” Robison says.

Madin said the slimy swarm at Diablo would probably go away in a few days, carried off by currents. Or, says Robison, they’ll quickly die off when their food supply runs out.

So the best bet, experts say, is for nuclear officials to just wait it out in the short term. "Long term, perhaps if their intakes were a bit deeper, it would not be a problem," Haddock said.

Despite the reactor outage, California is not expected to experience any electricity shortages because it has ample reserves, said Stephanie McCorkle, spokeswoman California ISO, which operates the state's power grid and wholesale markets.

It’s not the first time that sea creatures have interfered with nuclear plant activity.

In 2008, a swarm of jellyfish led to a sharp decrease in power generation at Diablo Canyon, according to the Los Angeles Times.  Similar jellyfish problems have cropped up at nuclear plants in the U.S., Japan, Israel and Scotland over the years, the newspaper said.

“It happens. It’s something you would expect along the coast,” Uselding said.

Madin said this is the first time he’s heard of salps interfering with the operation of a nuclear plant.

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Jim Cole / AP

93-year-old anti-nuclear activist Francis Crowe, center, and her friend Anneke Corbett are escorted off the property of Entergy Corp. in Brattleboro, Vt. after being arrested for trespassing.

BRATTLEBORO, Vt. -- A 93-year-old anti-nuclear activist was among more than 130 protesters arrested at the corporate headquarters of the Vermont Yankee nuclear power plant Thursday, the first day of the plant's operation after the expiration of its 40-year license.

Frances Crowe, of Northampton, Mass., said she wants Vermont Yankee to cease operations because she feels it's a threat to the people who live nearby.

"As I was walking down, all I could think of was Fukushima and the suffering of all the people, and I don't want that to happen to New England," said Crowe in referring to the Japanese nuclear reactor damaged last year after an earthquake and tsunami.

Fukushima disaster response frighteningly similar to Chernobyl

When asked how many times she'd been arrested, she answered: "Not enough."

A heavy police presence and ropes blocked off access to the offices in Brattleboro. The arrests were made calmly and without any confrontation, with obvious signs that protesters and police had worked out the logistics beforehand.

Unlawful trespass
Brattleboro Police Chief Gene Wrinn said in a statement that more than 130 people had been arrested for unlawful trespass. He said after being processed, they were later released.

The Brattleboro Reformer reported that Thursday's protest was the largest in Vermont in 25 years.

A company spokesman said work continued as normal at the plant 10 miles south in Vernon.

"We greatly appreciate the backing of our supporters and respect the rights of opponents to peacefully protest," said a statement issued by company spokesman Larry Smith. "Inside the gates, our employees will not be distracted. As it is every day, their focus on safety will be laser sharp."

'Shut it down'
A crowd estimated at more than 1,000 gathered in a downtown Brattleboro park before they marched the 3 ½ miles to the headquarters. Some marched on stilts. Others with painted faces carried signs that read "hell no, we won't glow." Many chanted: "Shut it down."

Gov. Peter Shumlin was sympathetic to the protesters.

"I am very supportive of the peaceful protesters gathered today in Brattleboro to express their — and my — frustration that this aging plant remains open after its agreed-upon license has expired," he said.

Jim Cole / AP

Hundreds of anti-nuclear activists march to the local corporate offices of Vermont Yankee owner Entergy Corp. in Brattleboro, Vt., on Thursday.

In a coordinated action in New Orleans, the headquarters of Vermont Yankee's parent company, Entergy Nuclear, another group of seven activists was arrested after going into the building and refusing to leave, police said. The Journal News reported that five others also were arrested at Entergy offices in White Plains, N.Y.

Loyola University law professor Bill Quigley said the New Orleans protesters live near the Vermont plant and traveled to Louisiana to request a meeting with Entergy CEO J. Wayne Leonard. They didn't get that meeting before they were arrested.

"We're trying to tell Entergy that the whole world is watching, and you can't pollute in one area of the country without consequences for everybody," Quigley said.

Radioactive tritium leaks from 48 US nuke sites

The federal Nuclear Regulatory Commission has issued the plant a 20-year license extension, but the state of Vermont wants the plant to close and the two sides are fighting a legal battle. In January, a federal judge issued an order that allows the plant to continue operating while the legal case continues in court.

Handcuffed
While the protesters gathered on the Brattleboro Commons, Vermont Yankee supporters sat across the street and watched. A half-dozen signs saying "VT4VY" were posted on the lawn.

"The thing is these people are not going to realize it until it's too late what a benefit it is down there. I feel bad for them. I don't think they're looking at the big picture," said Steve Shaclumis of Brattleboro.

Some protesters, including Crowe, were released immediately with citations to appear in court. Others were handcuffed and led onto a waiting school bus. It was expected they would be taken to a police station and then released.

According to The New York Times, the cost of decommissioning a single reactor is estimated at $400 million to $1 billion.

The newspaper reported on Tuesday that Entergy "is at least $90 million short of the projected $560 million cost of dismantling Vermont Yankee."

The Associated Press and msnbc.com staff contributed to this report.

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Updated at 12:45 p.m., ET: WASHINGTON -- A 30,000-pound bunker buster bomb designed to smash through some 200 feet of concrete before exploding is a "great weapon" that could be used by U.S. forces in a clash with Iran over its nuclear program, an Air Force general said on Thursday.

Israel stepped in line, asking the United States for the advanced bombs and refueling planes that could aid an Israeli strike on Tehran's underground nuclear sites, an Israeli official told Reuters on Thursday. 

"Such a request was made" around the time of Israeli Prime Minister Benjamin Netanyahu's visit to Washington this week, the official said, confirming media reports.

But the official, who spoke on condition of anonymity given the sensitivity of the issue, played down as "unrealistic" reports that the United States would condition supplying the hardware on Israel promising not to attack Iran this year.

Netanyahu told President Barack Obama at a White House meeting on Monday that Israel had not yet decided on military action against Iran, sources close to the talks said.

'A great weapon'
Serious talk of the buster bomb surfaced on Thursday after a high-raking military official described the bomb, designed to smash through some 200 feet of concrete before exploding, as a "great weapon” and could be used by U.S. forces in a clash with Tehran over its nuclear program.

Lieutenant General Herbert Carlisle, Air Force deputy chief of staff for operations, said the massive ordnance penetrator, which the military began receiving only last year, is part of the U.S. arsenal available for strikes against countries like Iran, which has some buried nuclear facilities.

"The massive ordnance penetrator is a great weapon. We are continuing to improve that. It has great capability now and we are continuing to make it better. It is part of our arsenal and it will be a potential if we need it in that kind of scenario," Carlisle told a conference on U.S. defense programs.

The Pentagon has begun working on military options if sanctions and diplomacy fail to prevent Tehran from building a nuclear weapon.

World powers to Iran: Open Parchin military site to IAEA inspectors

Defense Secretary Leon Panetta told the National Journal in an interview on Thursday that planning had been going on "for a long time."

Major powers are increasingly concerned about Iran's nuclear enrichment program, which they view as an attempt to build an atomic weapon. But Tehran says it is meant for peaceful energy production.

Israel holding off?
Israel is worried about potential for Iran to acquire nuclear weapons. Netanyahu said during his Washington visit that time was running out for diplomacy and sanctions.

Nevertheless, Netanyahu reportedly is willing to wait at least a few weeks to let sanctions work.

"I am not standing with a stopwatch in hand. It is not a matter days or weeks, but also not a matter of years. Everybody understands this," Netanyahu told an news program in Israel according to Britain's Telegraph newspaper.

"We would be happy if this thing is resolved peacefully, if Iran decides to stop its nuclear program," he said according to the Telegraph. "To stop it, to dismantle its facility in Qom, and to stop enriching uranium. I will be most happy, I think all Israel's citizens will also be happy."

Panetta, who has said diplomacy and sanctions should be given more time, told the National Journal he did not think Israel had decided whether to order a high-risk raid on Iran's nuclear sites.

He said the United States was committed to preventing Iran from acquiring atomic weapons and would have a greater impact than Israel if it decided force was necessary.

"If they decided to do it there's no question that it would have an impact, but I think it's also clear that if the United States did it we would have a hell of a bigger impact," Panetta said.

The tough rhetoric from the Pentagon came despite President Barack Obama's effort this week to tamp down "loose talk" and "bluster" about possible military action, saying there was still an opportunity for diplomacy.

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Just days before what could be the most consequential meeting of U.S. and Israeli leaders in years, aides to President Barack Obama and Prime Minister Benjamin Netanyahu are scrambling to bridge stark differences over what Washington fears could be an Israeli attack on Iran's nuclear sites.

With tensions between Israel and Iran running sky high, U.S. officials and military analysts are growing concerned that Israel will launch a multi-phase air and missile attack that could trigger waves of retaliatory missile strikes from Tehran.

That could quickly spiral into a regional conflict that would potentially force the U.S. to intervene to protect its interests.

Israeli voters disapprove of attack on Iran without US help

Further complicating Monday's White House talks is a trust deficit between the two men that has been magnified by mounting pressures of the U.S. presidential campaign. Obama's Republican foes are eager to paint him as too tough on Israel and too soft on Iran.

Netanyahu is coming to Washington to press Obama to more forcefully declare "red lines" that Iran must not cross in its nuclear program, Israeli officials say, even as speculation mounts that the Jewish state could act militarily on its own in coming months.

"If you don't want me to attack now, I want guarantees," an Israeli official quoted Netanyahu telling top Obama aides who visited Jerusalem last month. "If you're saying, 'we'll take care of you', you're not saying that clearly enough."

US, Britain urge Israel not to attack Iran

The White House has signaled that Obama, who has pledged to prevent Iran from building a nuclear weapon but has been vague on how far he is prepared to go, will resist pressure for a public policy shift.

Time running out?
Instead, amid growing signs that U.S.-led international sanctions are starting to take a toll on Iran, he will seek to persuade Netanyahu to hold off on any military strike to give those measures and diplomacy time to work, U.S. officials say.

But Israeli officials say they fear that time is running out for an effective Israeli attack as Iran buries its uranium enrichment program deeper underground.

Monday's meeting was supposed to have been a defining moment for the American and Israeli leaders, a chance to present a united front as international pressure on Iran intensifies.

Calls for a tougher approach on Iran are also coming from Republican presidential hopefuls, who see Obama as vulnerable on the issue as he seeks re-election and will seize on any public rift with Netanyahu.

Netanyahu will be pushing not only for Obama's acceptance of whatever action Israel decides to take but for stronger language against Iran that goes beyond the "all options are on the table" mantra on U.S. intentions, Israeli officials said.

Fears grow of Israel-Iran missile shootout

Washington has been working to convince the Israelis that a go-it-alone attack would cause only a temporary setback to Tehran's nuclear ambitions while possibly plunging the already-volatile Middle East into chaos.

And Obama's aides insist that an explicit U.S. military threat would be counterproductive right now, especially due to the potential for further spikes in global oil prices and the risk that Tehran might backtrack on overtures seen as opening the door to renewed nuclear talks with world powers.

Slideshow: Everyday life in Iran

At schools, in shops, and on the streets of big cities and small towns, daily life plays out in Iran.

Launch slideshow

But a source close to the administration's thinking on Iran told Reuters the president might try to placate some of Netanyahu's concerns in private and could also pledge even more sanctions to tighten the vise on Tehran.

The White House has proposed the two leaders issue a joint statement after they meet, but the idea has yet to be firmed up, an Israeli official said. A show of solidarity on certain issues might help keep differences under wraps on others.

An administration official also would not rule out the possibility that Obama could harden some of his rhetoric on Iran when he addresses the largest U.S. pro-Israel lobby in Washington on Sunday, the day before he sees Netanyahu.

Israel wary of Washington
Despite that, U.S. officials doubt that Netanyahu will go as far as providing assurances that Israel will consult Washington -- its biggest source of military assistance -- before launching any strikes on Iran, which has called for the destruction of the Jewish state.

Religious, political hard-liners face off in Iran election

Even if Obama privately reassures Netanyahu that the U.S. has the firepower to deliver a devastating blow to Iran's nuclear program further down the line, the Israelis have made clear they cannot rely on that commitment alone.

"Anyone who thinks that Israel is not going to make its own decision, particularly on an issue they view in existential terms, is kidding themselves," Obama's former Middle East adviser, Dennis Ross, told Reuters.

One line of thinking within the Obama administration is that keeping it in the dark about any Israeli military plans might be best for the United States since any sign of complicity would inflame anti-American sentiment in the Muslim world.

But even without a direct U.S. role, there will be deep suspicion across the Middle East that Israel would not act without a green light from Washington.

Still, it remains unclear whether Netanyahu will pay much heed to Obama's words of caution.

Some Obama aides remain suspicious of Netanyahu's motives. They are convinced that he would prefer to see a Republican take control of the White House in 2013 for fear that Obama's re-election would give him a freer hand to push anew for Israeli concessions to the Palestinians during a second term.

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The San Onofre nuclear generating plant in San Diego County, Calif, is pictured in this March 14, 2011 file photo.

A worker was leaning over to retrieve a flashlight when he lost his balance and fell into a reactor pool at the San Onofre nuclear power plant last week but he did not receive a significant dose of radiation, Southern California Edison officials said on Friday.

The worker was wearing a life preserver when he fell into a pool more than 20 feet deep that holds water that circulates through the reactor core.

He received 5 millirems of radiation, Gil Alexander, a spokesman for plant operator Southern California Edison, told the North County Times.

Read the original story on NBCLosAngeles.com

That's not considered a major dose and he went back to work the same day. By comparison, a chest X-ray provides about a 4-millirem dose.

The worker fell into the pool Jan. 27, five days before officials reported an "extremely small" amount of radiation could have escaped from the plant after a water leak prompted operators to shut down the reactor.

Read more: 'Extremely small' radiation release at Claif. plant possible, utility says

Alarms alerted station personnel to the leak at the power plant at about 6 p.m. Tuesday, according to the U.S. Nuclear Regulatory Commission.

Because the building into which the gas leaked is not airtight, it is possible that a small amount of radioactivity escaped into the environment, officials said. But he said the levels would likely be immeasurable against existing levels in the atmosphere.

The leak occurred in the part of the facility, located off the I-5 just south of San Clemente, which houses thousands of tubes carrying radioactive water, officials said.

There are radiation detectors throughout the plant and none measured any amount of radioactivity, said Alexander.

The investigation into what caused Tuesday's leak continues. An evacuation was not required.

Officials were waiting for the reactor to cool before crews were sent in to analyze and fix the leak.

Once the problem is resolved, it will likely take several days for the reactor to be restarted, officials said.

This was not the first time a leak scare has occurred at the San Onofre plant. In November, a level 1 alert was issued at the plants, but the appropriate alarms did not go off.

The Associated Press contributed to this report.

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