The primary use for nuclear bombs is destruction of an enemy in a conflict. There have been attempts since World War II to find peaceful uses such as digging canals and fracking for natural gas but none of them turned out to practical and safe. There is a new peaceful use of nuclear warheads that has been tossed around for a few decades, but we have not had an opportunity to test such a use.
      Twenty years ago, there was a movie that featured this new use. In the movie, Armageddon, a team flew to an incoming asteroid to plant nuclear warheads which blew the asteroid apart and saved human civilization. While the probability of a major asteroid striking the Earth is low, the consequences could be catastrophic such as the asteroid that ended the reign of the dinosaurs sixty-five million years ago. Asteroids that cross Earth’s orbit and might strike the Earth are referred to as Near Earth Objects (NEO). 
             In 2013, a meteor hit the ground in Chelyabinsk, Russia. It damaged property and injured more than a thousand people. This event moved asteroid strikes from a subject for science fiction to a real possibility that had to be taken seriously. Major nations such as the U.S. and Russia as wells as groups of nations such as the European Union began spending serious money to detect NEOs and develop possible responses to the threat of an impact.
       The U.N. has created the start of an international institutional infrastructure to detect and divert asteroids. Scientists and government officials have decided that nuclear warheads may be the best hope to divert incoming asteroids. The U.S. and Russia have discussed cooperating on a nuclear planetary defense initiative.
       One problem with developing a nuclear response to asteroid threats has to do with the current treaties governing activities in Earth orbit and outer space. Nuclear non-proliferation is written into space law. Under the current laws, any use of nuclear weapons to divert an incoming asteroid would violate international space laws.
      Article I(1)(a) of the 1963 Partial Test Ban Treaty prohibits the detonation of a nuclear device in space. Any attempt to blow up an approaching asteroid would obviously violate this law. (Not all nations with nuclear weapons and space launch capability are subject this law.)   In Article IV of the 1967 Outer Space Treaty, there is a prohibition against stationing nuclear weapons in space. This means that if an asteroid defense system included nuclear warheads in Earth orbit, it would violate this law.
      While it is important for the nations of Earth to abide by treaties and laws that are to the benefit of all, if it is established that an asteroid is headed our way, it is unlikely that these treaties would stand in the way of an attempt to use nuclear warheads to divert the asteroid. Russia has already hinted that if they saw an asteroid headed this way, they would “launch first, litigate second.”
      On the other hand, the excuse that an asteroid might some day threaten the Earth could be used to justify the development of new nuclear weapons and the launch of nuclear warheads into space. Blatant violation of international law would also allow the perpetrator to avoid the safeguards built into the law. In the end, it may be more dangerous to allow nuclear warhead into space than to worry about a possible asteroid strike in the future.
       It would seem that the international treaties about space law need to be updated. There has to be a way for space law to protect us from the use of an asteroid threat to avoid the regulations against the deployment of nuclear weapons in Earth orbit and beyond. In addition, the law does need to provide some sort of exemption for a multilateral nuclear planetary defense should it ever be needed. In such a case, the threat would need to be identified and verified and a nuclear response would need to be chosen by scientists as a best response. A multinational decision-making and oversight body made up of as many nations as possible should be created to deal with these issues.
        This will be very complex, time consuming and expensive to do but if the future of the human race is at stake, it will be worth any effort necessary.

Ambient office  =  81 nanosieverts per hour

Ambient outside = 80 nanosieverts per hour

Soil exposed to rain water = 87 nanosieverts per hour

Pineapple from Central Market = 63 nanosieverts per hour

Tap water = 141 nanosieverts per hour

Filtered water = 136 nanosieverts per hour

Part 2 of 2 Parts (Please read Part 1 first)
        In order to safely squeeze more power out of nuclear reactors, much better modeling of the processes leading to CHF is needed. Baglietto says, “Previous models were based on clever guesses, because it was impossible to see what was actually going on at the surface where boiling took place, and because models didn’t take into account all the physics driving CHF.”
       When he undertook the CASL project, his goal was to create a comprehensive, high fidelity model of boiling heat transfer processes up to the point where CHF occurs. This required the creation of very accurate models of the actual physical movement of bubbles, boiling and condensation that take place on the surface of the cladding of the nuclear fuel rods. There are tens of thousands of such rods in a typical nuclear power reactor.
       Baglietto made use of existing knowledge of the complex heat transfer process in the reactors for his work but he also acquired new experimental data to verify his results. He got assistance from Norman C. Rasmussen, Assistant Professor of Nuclear Science and Engineering, and Jacopo Buongiorno, the TEPCO Professor and associate department head for nuclear science and engineering at MIT.
       A physical model was constructed which included electrically simulated heaters, surrogate fuel assemblies and transparent walls. This allowed Baglietto’s team to collect details on the process of going from boiling to CHF. Baglietto says, “You’d go from a situation where nice little bubbles removed a lot of heat, and new water re-flooded the surface, keeping things cold, to an instant later when suddenly there was no more space for bubbles and dry spots would form and grow.”
       These experiments resulted in the confirmation of a fundamental fact. Baglietto’s first models suggested that during boiling, evaporation does not exclusively account for significant heat removal. Simulation experimental results showed that when bubbles slid, bounced around with other bubbles and left the heating surface, they carried away more heat than evaporation.
       W. David Pointer is the group leader of advanced reactor engineering at the Oak Ridge National Laboratory. He is not part of the CASL research team. He said, “Baglietto’s work represents a landmark in the evolution of predictive capabilities for boiling systems, enabling us to model behaviors at a much more fundamental level than ever possible before. This research will allow us to develop significantly more aggressive designs that better optimize the power produced by fuel without compromising on safety, and it will have an immediate impact on performance in the current fleet as well as on next-generation reactor design.”
       Experts says that Baglietto’s findings will be quickly put to work improving nuclear fuels. It is hoped that in the future, Baglietto’s research may be able to allow better cladding for the nuclear fuel rods that would be more accident tolerant, more resistant to impurities. This will improve wettability which makes surfaces more prone to contact with water and less likely allow the formation of dry spots.
        Baglietto says, “If fuel performs five percent better in an existing reactor, that means five percent more energy output, which can mean burning less gas and coal,” he says. “I hope to see our work very soon in U.S. reactors, because if we can produce more nuclear energy cheaply, reactors will remain competitive against other fuels, and make a greater impact on CO2 emissions.”

Ambient office  =  84 nanosieverts per hour

Ambient outside = 77 nanosieverts per hour

Soil exposed to rain water = 77 nanosieverts per hour

Carrot from Central Market = 79 nanosieverts per hour

Tap water = 95 nanosieverts per hour

Filter water = 84 nanosieverts per hour

Part 1 of 2 Parts
       I have often said that nuclear power reactors are the most expensive, complex and dangerous way to boil water ever invented by the human race. The nuclear reactions in the reactor core generate enormous heat. This results in a maelstrom of boiling, bubbling and evaporation on the surface of the fuel rods in the core. The heat is ultimately transferred from this core activity through the cooling system to create steam which is used to drive the turbines that generate the electricity. Scientists have spent a lot of time trying to analyze and predict the physical processes involved in this heat transfer but have only had limited success.
       Emilio Baglietto is an associate professor of nuclear science and engineering at MIT. He is thermal hydraulics lead for the Consortium for Advanced Simulation of Lightwater Reactors (CASL). This is an initiative that was started in 2010 with support from Department of Energy’s Consortium for Advanced Simulation of Light Water Reactors for the purpose of designing predictive modeling tools to assist the improvement of current and future nuclear power reactors. In addition, CASL is working on insuring that nuclear reactors can be economically viable as a major source of power for our world. Baglietto’s team includes Etienne Demarly who is a doctoral candidate in nuclear science and engineering at MIT and Ravikishore Kommajosyula who is a doctoral candidate in mechanical engineering and computation at MIT.
       Baglietto has recently made an important breakthrough in characterizing the physical processes of heat transfer. His team is using a modeling system called computations fluid dynamics (CFD). They have created new CFD models that accurately capture the basic physics involved in the boiling of coolants in nuclear reactor cores. It is now possible to model the rapidly evolving heat transfer phenomena at the microscale in a variety of reactor designs under different operating conditions. Baglietto says, “Our research opens up the prospect of advancing the efficiency of current nuclear power systems and designing better fuel for future reactor systems.”
      A critical issue for the work of CASL involves something called critical heat flux (CHF). Baglietto says that CHF “represents one of the grand challenges for the heat transfer community.” CHF describes a situation where, during boiling, there is a sudden loss of contact between the boiling liquid and the heating element. This is what happens in the core of a nuclear reactor. When power levels change in a reactor, CHF can suddenly appear. The boiling reaches a crisis where a vaporous film covers the surface of the heating element which consists of nuclear fuel rods. Dry spots form on the surface of the fuel rods and quickly reach very high temperatures.
      Baglietto explains that, “You want bubbles forming and departing from the surface, and water evaporating, in order to take away heat. If it becomes impossible to remove the heat, it is possible for the metal cladding to fail.” “We want to allow as much boiling as possible without reaching CHF,” says Baglietto. “If we could know how far we are at all times from CHF, we could operate just on the other side, and improve the performance of reactors.”
        The allowed power setting for operation of a commercial nuclear power reactor set by nuclear regulators are far below the point at which CHF might occur. On a practical level, this means that most power reactors are operating way below their potential energy levels.
Please read Part 2

Ambient office  =  92 nanosieverts per hour

Ambient outside = 84 nanosieverts per hour

Soil exposed to rain water = 83 nanosieverts per hour

Beefsteak tomato from Central Market = 72 nanosieverts per hour

Tap water = 93 nanosieverts per hour

Filter water = 87 nanosieverts per hour