The Department of Energy's long-term plan for dealing with material contaminated with plutonium and heavier elements from the U.S. weapons program is to bury it underground at the Waste Isolation Pilot Plant in southeastern New Mexico.

The Energy Department's plan aims to safeguard nuclear material for the next 10,000 years. But three Stanford nuclear scientists point out in a new commentary article in the journal Nature that the Waste Isolation Pilot Plant (WIPP) was not designed to hold as much plutonium as is now being considered for disposal there. And, in fact, the site has seen two accidents in recent years.

"These accidents during the first 15 years of operation really illustrate the challenge of predicting the behavior of the repository over 10,000 years," said Rod Ewing, the Frank Stanton Professor in Nuclear Security at Stanford and a senior fellow at the Center for International Security and Cooperation.

What's more, there's more plutonium proposed for disposal at WIPP in the future, a result of treaties with the former Soviet Union and now Russia to decrease the number of nuclear weapons by dismantling them.

A recent assessment of what to do with the plutonium from dismantled weapons has proposed that the material be diluted and disposed of at WIPP. But this analysis does not include a revision of the safety analysis for the site, wrote Ewing and his two Stanford co-authors in the Department of Geological Sciences, postdoctoral scholar Cameron Tracy and graduate student Megan Dustin.

They call on the U.S. Department of Energy, which operates WIPP, to take another look at the safety assessment of the site. Particular emphasis should be on the estimates of drilling activity in the oil-rich Permian Basin, where WIPP is located, and on the effects of such a huge increase in the plutonium inventory for the pilot plant.

"The current regulatory period of 10,000 years is short relative to the 24,100-year half-life of plutonium-239, let alone that of its decay product, uranium-235, which has a half-life of 700 million years," the researchers wrote.

"We cannot be certain that future inhabitants of the area will even know WIPP is there," they added. As a result, it is important to understand the impact of future drilling in the area.

The waste is stored 2,150 feet below the surface in hundreds of thousands of plastic-lined steel drums in rooms carved out of a 250-million-year-old salt bed. The repository is at about half of its planned capacity and slated to be sealed in 2033.

The researchers question some of the assumptions used in the safety studies. For example, to determine the odds of oil drilling in the future, the study uses a 100-year historical average drill rate, even though drilling has intensified in recent decades, throwing this assumption into question.

The Stanford experts also suggest more attention to how the buried materials may interact with each other, particularly with salty brine, over centuries. A single storage drum may contain a variety of materials, such as lab coats, gloves and laboratory instruments; thus, the chemistry is complex.

Ewing said that the complacency that led to the accidents at WIPP can also occur in the safety analysis. Therefore, he advises, it is important to carefully review the safety analysis as new strategies for more plutonium disposal are considered.

Former Los Alamos National Laboratory director Siegfried Hecker assesses North Korea’s claim to have detonated a hydrogen bomb in an underground nuclear test this week. Hecker is one of the world’s top experts on the North Korean nuclear program. He has visited North Korea seven times since 2004, and is the only Western scientist known to have ever been inside a North Korean uranium enrichment facility. He is currently a senior fellow at Stanford’s Center for International Security and Cooperation, and a research professor of Management Science and Engineering.

Do you believe that North Korea actually detonated a hydrogen bomb in its latest nuclear test?

I don’t believe it was a real hydrogen bomb, but my greatest concern is not so much whether or not they actually tested a hydrogen bomb, but rather that they tested at all. Since this test worked, they will have achieved greater sophistication in their bomb design – that is the most worrisome aspect. This is their fourth test – with each test they can learn a lot.

What makes a hydrogen bomb a more threatening weapon than a conventional atomic bomb?

A hydrogen bomb can be a hundred or a thousand-fold more powerful than a fission bomb. Certainly a blast of a megaton will be much more destructive than the Hiroshima bomb, but the more important part is the ability to deliver at long range and to do it accurately. That is what would threaten the United States and its allies most; even with the size of nuclear blasts they have already demonstrated.

White House officials say that initial data from nearby monitoring stations are not consistent with a hydrogen bomb test. How will we know for sure whether it was a hydrogen bomb or not?

The short answer is that we may never know. The telltale signs of a hydrogen bomb are very difficult to pick up in a deeply buried test. Typically hydrogen bombs have greater explosive power or yield. This test is currently believed to have resulted in a seismic tremor of 5.1 on the Richter earthquake scale. That would make it roughly equivalent to the third nuclear test in February 2013. At that time, North Korea claimed it tested a miniaturized atomic bomb – there was no mention of a hydrogen bomb. My estimate of the yield for the 2013 test is roughly 7 to 16 kilotons – which is in the range of the 13-kiloton Hiroshima blast. As far as destructiveness, a Hiroshima-scale explosion is bad enough. Detonated in Manhattan, it may kill as many as a quarter million people. The power of the 2013 and the current explosion is more consistent with fission bombs than hydrogen bombs.

Can you rule out the possibility that it was a hydrogen bomb?

I find it highly unlikely that the North tested a real hydrogen fusion bomb, but we know so little about North Korea’s nuclear weapons design and test results that we cannot completely rule it out. A modern hydrogen bomb is a two-stage device that uses a fission bomb to drive the second stage fusion device. A two-stage device is very difficult to design and construct, and is likely still beyond the reach of North Korea today. However, by comparison, China’s early nuclear weapon program progressed rapidly. It tested its first fission bomb in 1964 and less than three years later demonstrated a hydrogen bomb – and that was 50 years ago. North Korea has now been in the nuclear testing business for almost 10 years, so we can’t rule anything out for certain.

If it wasn’t a hydrogen bomb, what kind of bomb might it have been?

What may be more likely than a two-stage hydrogen bomb is that they took an intermediate step that utilizes hydrogen (actually hydrogen isotopes) fuel to boost the explosive yield of the fission bomb, a sort of turbocharging. Such a device has a fusion or “hydrogen” component, but is not a real hydrogen bomb. It allows miniaturization – that is making the bomb smaller and lighter. Moreover, it would be the first step toward eventually mastering a two-stage hydrogen bomb.

The most important aspect then is to miniaturize, whether it is a fission bomb, a boosted fission bomb, or a hydrogen bomb. The Nagasaki bomb weighed 5,000 kilograms. It was delivered in a specially equipped B-29 bomber. North Korea wants to demonstrate it has a deterrent. To do so, it needs to be able to credibly threaten the U.S. mainland or our overseas assets. For that, you have to make the bomb (more correctly, the warhead) small enough to mount on a missile. The smaller and lighter, the greater the reach. At this point, what makes their nuclear arsenal more dangerous is not so much explosive power of the bomb, but its size, weight and the ability to deliver it with missiles.

How close is North Korea to being able to credibly threaten a nuclear strike against the mainland United States?

North Korea is still a long way off from being able to strike the US mainland. It has only had one successful space launch. It needs a lot more, but it has a large effort in that direction.

Do you think North Korea conducted this test for political or technical reasons?

North Korea had very strong technical and military drivers for this test, as well as follow-on tests. The political environment is mostly what has constrained it from testing earlier and more often. However, this test demonstrates that Pyongyang is willing to weather the political storm this test will bring. It has done so for all previous tests.

What are your current estimates on the size of North Korea's stockpile of nuclear weapons and materials?

Much like in the area of sophistication of the bomb, we have little information of what North Korea actually possesses. The best we can do is to estimate how much bomb fuel, plutonium and highly enriched uranium, they may have produced and estimate how many bombs they can produce from that stockpile. My best estimate at this time is that they may have enough bomb fuel for 18 bombs with a capacity to make 6 to 7 more annually. That, combined with the increased sophistication they surely achieved with this test, paints a troublesome picture.

How should the U.S. respond?

I am concerned about we haven’t done to date. Washington has lost many opportunities we have had since North Korea began its nuclear weapon production in earnest in 2003. One thing that’s clear is that doing what we and the rest of the world have done so far – half-hearted diplomacy, ultimatums, and sanctions – have failed, so these are not the answer. I have previously argued that we should focus on three “No’s” for three “Yes’s” – that is no more bombs, no better bombs (meaning no testing) and no export – in return for addressing the North’s security concerns, its energy shortage and its economic woes. This could have worked when I first proposed it 2008 after one of my seven visits to North Korea. It will be more difficult now.

Former U.S. Secretary of Defense William J. Perry said he was concerned that the Islamic State in Iraq and Syria (ISIS) could buy, steal or build a nuclear weapon capable of killing a hundred thousand or more people in a single strike.

And, he said, stopping the flow of oil money to ISIS should be the main, short-term objective of the United States and its allies in the fight against the terrorist organization.

“They have demonstrated their objective is just killing as many Americans as they can, or Europeans as the case may be…and there is no better way of doing that than with nuclear weapons,” Perry said.

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“If they can buy or steal a nuclear bomb, or if they could buy or steal fissile material, they could probably make a bomb – a crude improvised bomb,” he said.

Even a crude nuclear weapon could have an explosive power equivalent to around fifteen thousand tons of TNT – similar to the bomb that destroyed the Japanese city of Hiroshima near the end of World War II.

Perry said there was evidence that Al Qaeda had actively tried to get nuclear weapons, and he said it was likely that ISIS was also pursuing its own nuclear strategy.

“The big difference between ISIS and Al Qaeda in that respect is that ISIS has access to huge amounts of resources through the oil that they now control,” Perry said.

“I believe that our primary objective in dealing with ISIS should be to stop that flow of money, stop the trading they’re doing in oil which is giving them the resources.”

U.S. warplanes reportedly destroyed 116 trucks in Eastern Syria on Monday that American officials said were being used to smuggle crude oil.

U.S. fighter jets dropped leaflets before the attack, warning the drivers to abandon their vehicles, according to a report in The New York Times.

The Russian Air Force also claimed its planes had struck around 500 oil tankers that were carrying oil from Syria to Iraq for processing.

Perry said that combating ISIS over the long run was a “hugely difficult problem” for Western powers.

“To really stop ISIS completely it would be a long and brutal and ugly fighting on the ground, which I don’t believe we’re going to want to do again,” he said.

“What we can do however, a more limited objective is stopping the resources they’re getting, stopping their access to this oil money. And that limits quite a bit what they can do…That can be done I think in more of a targeted and effective way, and without having to put armies on the ground to do it.”

In an NK News' series of interviews with a panel of U.S. experts on North Korea policy, David Straub, associate director of the Korea Program and former State Department Korea director, analyzes the U.S. approach toward Pyongyang. With NK News' permission, downloadable PDF versions of the interviews are available below.