Radiation Contained Inside Three Mile Island

A small amount of radiation has been detected in a reactor building at the Three Mile Island nuclear power plant.

According to TMI spokesperson Ralph DeSantis, employees were working in a reactor building around 4:30 yesterday afternoon. It was part of the process of removing TMI’s old steam generators and installing the new steam generators that rolled into TMI in September.

DeSantis told abc27 that workers were cutting a large number of pipes. A radiation alarm sounded. According to DeSantis, employees inside the reactor building were wearing protective suits, but about 151 workers were monitored for exposure.Only a handful were contaminated. DeSantis said they were decontaminated and sent home. He said that the contamination was not at a threatening level and was contained to one building at Three Mile Island. He stressed that the public was not in any danger.

DeSantis told abc27 that the cause is not yet determined. The entire plant is now shut down. Once operating again, work will remain shut down in the reactor building.

via Radiation Contained Inside Three Mile Island|abc27 News.

My dentist has ordered a Cone Bean CT scan, is it worth the radiation risk?

My dentist referred me to a lab to get “tomos”. In talking to the lab, they would use Cat scans. My  dentist requires this  before he will attempt to straighten my teeth. He says this is the wave of the future. Unfortunately, I’ve also read recently, and my doctor has acknolweged, that they are learning now that there are non-trivial long term risks for lymphomas from diagnostic x-rays. For this reason, babies are no longer given x-rays unless it is absolutely necessary.

What would my dose for the iCAT scan be? The first thing you will hear if you ask is that the radiation dose is “minimal” or “negligable” or “trivial”. Don’t accept these answers. You want is actual numbers.

What the lab told me after doing some research is that the effective dose of the 20 second iCat scan is 68 uSV. The exposure is in pulses, 3.5 seconds for the 20 second scan. For comparison, an iCat 10 second scan gives you a 34 uSV dose, daily background radiation gives you an 8 uSV dose, a digital pano x-ray gives you a dose of 4.7 to 14.9 uSV.

Since I am concerned about minimizeing radiation, the lab said they can build the pano and latteral shots from the one 20 second iCat scan. What is the actual cancer risk from getting an extra weeks worth of radiation in 3.5 seconds of pulses?  Currently researching…

Cosmic pattern to UK tree growth

The growth of British trees appears to follow a cosmic pattern, with trees growing faster when high levels of cosmic radiation arrive from space.

Researchers made the discovery studying how growth rings of spruce trees have varied over the past half a century.

As yet, they cannot explain the pattern, but variation in cosmic rays impacted tree growth more than changes in temperature or precipitation.

The study is published in the scientific journal New Phytologist.

“We were originally interested in a different topic, the climatological factors influencing forest growth,” says Ms Sigrid Dengel a postgraduate researcher at the Institute of Atmospheric and Environmental Science at the University of Edinburgh.

To do this, Ms Dengel and University of Edinburgh colleagues Mr Dominik Aeby and Professor John Grace obtained slices of spruce tree trunks.

These had been freshly-felled from the Forest of Ae in Dumfriesshire, Scotland, by Forest Research, the research branch of the UK’s Forestry Commission.

The trees had been planted in 1953 and felled in 2006.

The researchers froze the trunk slices, to prevent the wood shrinking, then scanned them on to a computer and used software to count the number and width of the growth rings.

As the trees aged, they showed a usual decline in growth.

However, during a number of years, the trees’ growth also particularly slowed. These years correlated with periods when a relatively low level of cosmic rays reached the Earth’s surface.

via BBC – Earth News – Cosmic pattern to UK tree growth.

Natural nukes may have crippled early life

Ancient nuclear reactors buried in lake and shallow ocean sediments may have cooked early microbes, according to a new study. And radiation from the deposits could have delayed the onset of our modern-day, oxygen-rich atmosphere, and even had a hand in shaping the genetics of primordial life.

Natural nuclear reactors dating to 2 billion years ago have been found in Gabon, Africa. Though long since exhausted, scientists know from the unusually low quantity of the Uranium-235 isotope in the rock that they once went critical, and hosted a sustained fission reaction that went on for as long as two hundred thousand years.

A billion years earlier, such deposits could have been common, say Laurence Coogan and Jay Cullen of the University of Victoria. The first oxygen-producing bacteria colonized lakes and shallow seas, and likely created oxygen ‘oases’ in an otherwise nitrogen-dominated world.

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“Oxygen oases would have been hot spots for uranium concentration,” Cullen said, because oxygen dissolved in water would draw uranium out of rocks and sediments. “Back then, there was so much more 235U that a softball-sized chunk of uranium would be enough for it to go critical.”

If the researchers are right, wherever there were oxygen-producing bacteria, there were also natural nuclear reactors. Radiation could have damaged the bugs’ DNA, either directly from the reactors or as leftover atoms of radioactive strontium (Sr) and iodine (I) made their way into the food chain.

In short, organisms that produced oxygen 3 billion years ago were shooting themselves in the foot by spawning toxic nuclear reactors. That may explain why it wasn’t until around 2.3 billion years ago that oxygen finally started building up in the atmosphere. By then, Cullen said, most of the readily available nuclear fuel was used up.

However, it’s also possible the reactors had a positive effect on early life.

via Natural nukes may have crippled early life – Discovery.com- msnbc.com.

Cosmic Rays Hit 50-Year High – Yahoo!

Galactic cosmic rays have just hit a Space Age high, new data from a NASA spacecraft indicates.

“In 2009, cosmic ray intensities have increased 19 percent beyond anything we’ve seen in the past 50 years,” said Richard Mewaldt of Caltech. “The increase is significant, and it could mean we need to re-think how much radiation shielding astronauts take with them on deep-space missions.”

The surge, which poses no threat to Earth, was detected by NASA’s ACE (Advanced Composition Explorer) spacecraft. The cause of the surge is solar minimum, a deep lull in the sun’s activity that began around 2007 and continues today. Researchers have long known that cosmic rays go up when solar activity goes down, because strong solar activity inflates and bolsters a protective bubble around our entire solar system.

Right now solar activity — marked by sunspots, solar flares and space storms — is as weak as it has been in modern times, setting the stage for what Mewaldt calls “a perfect storm of cosmic rays.”

… Galactic cosmic rays come from outside the solar system. They are subatomic particles — mainly protons but also some heavy nuclei — accelerated to almost light speed by distant supernova explosions. Cosmic rays cause “air showers” of secondary particles when they hit Earth’s atmosphere, where they can pose a threat to orbiting satellites — a single cosmic ray can disable a satellite if it hits an unlucky integrated circuit. Though some have suggested that cosmic rays might be behind the Earth’s current warming climate, research has shown no firm link between these invading rays and global warming. Cosmic rays also pose a health hazard to astronauts. Several reports have outlined the risks from cosmic radiation that might exist for future missions to Mars or stints on the moon.

The sun’s magnetic field — the heliosphere, which surrounds the entire solar system —is our first line of defense against these highly-charged, energetic particles. But the current state of solar activity means the solar system isn’t as protected right now.

via Cosmic Rays Hit 50-Year High – Yahoo! News.

From NASA:

Galactic cosmic rays (GCRs) come from outside the solar system but generally from within our Milky Way galaxy. GCRs are atomic nuclei from which all of the surrounding electrons have been stripped away during their high-speed passage through the galaxy. They have probably been accelerated within the last few million years, and have traveled many times across the galaxy, trapped by the galactic magnetic field. GCRs have been accelerated to nearly the speed of light, probably by supernova remnants. As they travel through the very thin gas of interstellar space, some of the GCRs interact and emit gamma rays, which is how we know that they pass through the Milky Way and other galaxies.

The elemental makeup of GCRs has been studied in detail , and is very similar to the composition of the Earth and solar system. but studies of the composition of the isotopes in GCRs may indicate the that the seed population for GCRs is neither the interstellar gas nor the shards of giant stars that went supernova. This is an area of current study.

I was thinking, Yahoo! more energy! Lets tap it and use it … but this changed my mind:

Cosmic rays in outer space are abundant and diverse. There’s a whole periodic table worth of nuclei (mostly H, He, C, and Fe), electrons and positrons, neutrons, and high-energy photons (x rays, gamma rays) … ejected by solar winds, distant supernovae, and all sorts of ill-understood processes.

At the Earth’s surface things are completely different. The atmosphere is dense enough to stop basically everything that comes in (except neutrinos!) and only some of the secondaries, the by-products of the collisions that stopped the original particles, manage to percolate down. These secondary particles are typically lightweight (certainly nothing heavier than a proton) and most of them are pretty rare … a few protons and a few tens of electrons, say, per square meter per second.

The one secondary that doesn’t have to percolate is the muon. Muons produced very high in the atmosphere are able to penetrate all the way to the surface (and a ways underground as well!) without losing all of their energy. This is because they’re very heavy (lots of inertia) and they don’t interact strongly with nuclei (which is what stops cosmic-ray protons and neutrons so quickly). So muons are the most important component of cosmic rays at the surface.

When building and testing new particle detectors, we do see cosmic ray muons on a regular basis. They’re a quick and dirty way to make sure a detector is working properly: if it gets triggered too often, or too infrequently, with respect to the cosmic ray flux, then you want to know why. The number to remember is ~70 muons per square meter per second, or one per square centimeter per minute.

As for the energy flux? First of all, it’ll be fantastically small amounts of energy, when you think about it on the scales we’re used to. The mean muon energy is ~4 giga-electron-volts (GeV), so that gives you an energy flux of 280 GeV/second. But one electron volt is ~10^-19 joules. That’s fantastically small. This does’t imply that we can’t detect them; in fact, it’s not too hard to detect them at all, as you know if you’ve seen a simple cloud-chamber setup. Fortunately, even a tiny amount of energy – a few electron volts – is enough to ionize an atoms, and free ions and electrons are what we detect. But you’re not going to see your detector heating up.

You also mentioned one-foot-thick concrete walls and roof. Now, that will attentuate the muons somewhat … if you want an order-of-magnitude answer we can ignore it. It’ll be a factor of 2, not 10. This is calculable, though; check out Chapter 23 of “The Passage of Particles through Matter” in the Review of Particle Physics (click here). – madsci.org

Plutonium Batteries

Do the Mars rovers have plutonium batteries?

In fact, the Spirit and Opportunity rovers can stay warm and keep collecting data for nearly five times longer, thanks to about an ounce and a half of Los Alamos plutonium-238. Los Alamos’ Pu-238 Science and Engineering (NMT-9) Group made eight lightweight radioisotope heater units each for the Spirit and Opportunity rovers. Each of the 16 units contains just under one-tenth of an ounce of plutonium, and each pumps out a continuous one watt of heat as the plutonium decays. Housed inside the rover fuselages, called Warm Electronic boxes because they provide a temperature-controlled environment, the heater units keep electronic and mechanical components warm enough to function reliably in the bitter cold of space. They transfer heat directly to the rover systems and instruments, without moving parts or electronic components. The heater units are the latest in a long line of plutonium heaters and thermal batteries fabricated at Los Alamos for all of NASA’s deep space probes, as well as for the Sojourner rover, which explored the red planet for three months as part of NASA’s Pathfinder mission in the summer of 1997. The heat comes from plutonium-238, the shorter-lived and much hotter cousin of weapons-grade plutonium, or plutonium-239. – lanl.gov

NASA does have plans to use plutonium batteries on Mars:

… Nuclear powered, the big-car sized vehicle won’t suffer the serious constraints imposed by using solar power on Mars, further from the Sun than Earth. It will be able to tool about drilling into rocks (or “vapourising” them with its laser) for a full Martian year (nearly two Earth ones) before its plutonium battery pack runs out of puff. The MSL is a way over budget, seemingly, with $1.5bn already spent. There has been talk recently of cancelling it. However, it now seems clear that the programme will proceed. There’s more on MSL from NASA here – the register

The earliest working plutonium battery I’ve found a photo of so far is from 1973.  The first public reference I found was June 2, 1967 New York Times:

Jun 2, 1967 – They can operate in shadow or far out away from the sun where the cold of space would freeze ordinary batteries. They are considered particularly important for future military and civilian space missions that will require large amounts of power. i The first Navy units used plutonium

Going back farther, we know plutonium batteries were operating in space on October 24, 1961 based on this paper where Dr. Glenn T. Seaborg, Chairman of the US Atomic Energy Commission says at an International Symposium on Aerospace Nuclear Propulsion conference in Las Vegas:

How do Plutonium batteries work?

Space batteries work by converting heat from the radioactive decay of plutonium-238 — the sister to plutonium-239 used in nuclear weapons — into electricity. The batteries are considered the best power source for unmanned space vehicles, producing hundreds of watts of electricity for decades. The plutonium batteries aboard the Voyager 1 spacecraft, launched in 1977, were still working at 80 percent capacity when it left the solar system in 2003. – globalsec

Plutonium 238 is used in radioisotope thermoelectric generators, which convert the heat of radioactive decay into electricity to power long-distance spacecraft. The Cassini spacecraft… has three generators.

Neat stuff, right? Problem is, even a tiny speck of it can kill you.

All Things Considered, August 4, 2005 · Fifteen years ago, the United States stopped making plutonium-238, one of the most toxic substances known to man. It can be fa tal to inhale so much as a speck of the radioactive isotope. But now, citing national security needs, the government is preparing to start making it again at a federally owned site in the Idaho desert. Plutonium-238 is far more radioactive than its cousin, plutonium-239, which is used in bombs. It’s so radioactive, it stays hot to the touch for decades. It is useless for commercial nuclear power plants, but ideal to make small, long-lasting batteries for devices such as space probes and espionage equipment. – npr.org

This is an image of a glowing red hot pellet of plutonium-238 dioxide to be used in a radioisotope thermoelectric generator for either the Cassini mission to Saturn or the Galileo mission to Jupiter. This image was provided by the Department of Energy via email and was taken at the Department’s Los Alamos National Laboratory. Each pellet produces 62 watts of heat and when thermally isolated, can glow brilliant orange.. Excerpt from email: “The pellet is glowing red because of the heat generated by the radioactive decay (primarily alpha) of the fuel. [Photos of glowing pellets are typically taken after insulating the pellet under a graphite blanket for a period of time (minutes), removing the blanket, and taking the picture.] These pellets were used in the RTGs that powered NASA’s Galilleo and Cassini spacecraft on missions to Jupiter and Saturn, respectively. The pictures now being sent back from Saturn by the Cassini orbiter are made possible through this unique fuel source. – wiki

Could a pound of it kill everyone on earth? Not really.

In regard to the statement that 1 pound of Pu would kill everyone on Earth… One pound of plutonium would be enough to give 1.6E+9 persons a CDE of 50 rem (0.5 Sv) {which could result in 1.5E+5 additional cancers} *IF* and ONLY IF the material was pulverized into particles of respirable size and the material could be adequately dispersed in the atmosphere. A few decades ago the United States and other countries engaged in atmospheric nuclear bomb testing. These tests released many pounds of radioactive isotopes, including plutonium, to the atmosphere. Although there is some evidence of increased incidence of cancer among “downwinders”, there have not been 1.5E+5 cancers in excess of the number expected. So it would be practically impossible to kill everyone on earth with one pound of plutonium. – isu.edu

For now, plutonium batteries are still far too dangerous to use on earth. We did not always know this, it seems.  For example, there were once plutonium powered pacemakers. Theodore W. Gray. writes that he received the following information from Andrew Hansen:

The R9000 was circa about 1970 and was, by today’s standards, quite simplistic. It sold mostly behind the old iron curtain and some devices are still going but not many. The idea did not take off in the west for two reasons. The first is the hysteria of implanting plutonium. The second is that most pacemaker companies (and there are only 4 that sell world wide-the list goes up to about 6-8 if you include companies that sell in Europe only) and each company will bring out a new model every 1 to 2 years. Today’s devices use either lithium iodine or lithium monofluride batteries and last around 8 years. That means that by the time your battery runs out your device has been superseded at least 3 times.

… When the patient finally dies the mortician may look for and explant a pacemaker – they’re easy to see as they are implanted between the skin and the muscle in the upper chest just under one of the collar bones – but if the family plan to bury rather than cremate then the mortician may not bother.

Pacemakers must be explanted for cremation as a lithium iodine cell has a lot of really powerful chemistry in it – usually 1.2Ahr with a rundown curve that stays flat at the nominal voltage for 90% of its working life before a rapid rundown. If you incinerate one of those little beauties they will actually damage the furnace (which happened here in Oz some years back).

So you can see that it all hinges on the mortician and companies and other health care workers generally have very little contact with them so they have no idea what to do or what to look for.

Here is part of a letter in which the NRC fines a hospital regarding plutonium powered pacemakers:

In 1978, a patient was implanted with a nuclear pacemaker by staff at Lower Bucks Hospital (LBH) as authorized by LBH’s NRC license. The pacemaker was explanted at Nazareth Hospital on October 31, 1996, after the patient had expired. Although you were notified on November 2 or 3, 1996, that the patient had expired and that the pacemaker had been explanted, you did not contact the NRC within 24 hours, which constitutes one of the three violations. Also, on December 10, 1996, you were notified by a representative of Nazareth Hospital that the pacemaker could not be located and was assumed lost. Although you had contacted the supplier of the pacemaker to retrieve the pacemaker and properly dispose of it, you did not communicate effectively with Nazareth Hospital, to ensure appropriate control and disposal of the pacemaker. These failures resulted in two additional violations of NRC requirements.

Furthermore, during the inspection, the NRC learned of two additional instances (January 5, 1981 and September 18, 1983), in which pacemakers were buried with patients, and one additional instance in which the pacemaker was not returned to the supplier (August 1987). All three of these occurrences are similar to an occurrence at your facility in 1987 in which two pacemakers were buried with patients after the patients had expired. As the hospital that had initially implanted the pacemakers, as authorized by your NRC License No. SNM-1800, you were responsible for taking appropriate and timely action to ensure proper retrieval and disposal of pacemakers. This did not occur. Given the significance of improper disposal of this material, the violations have been classified in the aggregate as a Severity Level III problem in accordance with the “General Statement of Policy and Procedure for NRC Enforcement Actions” (Enforcement Policy), NUREG-1600. – nrc.gov

Other sources besides plutionium have been used for pacemakers. Click here for THE article on nuclear pacemaker batteries [.pdf]

Nuclear Powered Aircraft History + Smallest Nuke Power Plants

The audio is a bit fuzzy, but I didn’t know anything with a nuclear engine ever flew until I saw this:

Image: the HTRE-3,  Heat Transfer Reactor Experiment, without supporting structure. From the ATS forum:

Some time ago someone wrote question about General Electric X-211 nuclear engines. Here is the answer.

Under the ANP program the General Electric Co., at Evendale, Cincinnati was issued a contract to develop a direct-cycle turbojet, and Pratt & Whitney Aircraft Division of United Aircraft Corp. was authorized to study an indirect cycle and work was started at the Connecticut Aircraft Nuclear Engine Laboratory (CANEL). In the direct air cycle air enters through the compressor stage of one or more turbojets. From there the air passes through a plenum an is directed through the reactor core. The air, acting as the reactor coolant, is rapidly heated as it travels through the core. After passing through the reactor the air passes through another plenum and is directed to the turbine section of the turbojet(s) and from there out through the tailpipe. An indirect system is very similar, except that the air does not pass through the reactor itself. After passing through the compressor the air passes through a heat exchanger. The heat generated by the reactor is carried by a working fluid to this heat exchanger. The air then passes through the turbine and out the tailpipe as above. The working fluid in the indirect cycle is usually a dense fluid, such as a liquid metal, or highly pressurized water. This allows more heat energy to be transfer, thereby increasing the efficiency of the system. …

General Electric ran a series of very successful experiments using the direct cycle concept. These were referred to as the Heat Transfer Reactor Experiment (HTRE) series. The series involved three reactors, HTRE-1 through HTRE-3. HTRE-1 became HTRE-2 at the conclusion of its test program. HTRE-1 (and therefore HTRE-2) successfully ran one X-39 (modified J-47) solely under nuclear power. HTRE-3 was the closest to a flight article the program came. It was solid moderated, as opposed to the earlier reactors which were water moderated, and it powered two X-211s at higher power levels. HTRE-3 was limited by the two turbojets, but it could have powered larger jets at even higher power levels. The system was called XMA-1. HTRE-1 was principally a proof of concept reactor. HTRE-1 achieved a number of full-power runs that demonstrated conclusively the feasibility of operating a jet engine on nuclear power. HTRE-2 was simply HTRE-1 modified to test advanced reactor sections in a central hexagonal chamber. In this way new reactor designs could be tested without the need to build a totally new reactor from scratch. The experience gained from HTRE-1 and HTRE-2 was used in the construction of HTRE-3. HTRE-3 was the final test item designed to prove the feasibility of producing an actual aircraft powerplant. The design and testing of HTRE-3 has advanced the direct-cycle program beyond the question of feasibility to the problems of engineering optimization. …

The HTRE either met or exceeded their goals, but although all had reactor cores of roughly the size needed to fit into an aircraft, none of the HTREs were designed to be a prototype of a flight system; the series showed that it then appeared “possible and practical with the technology in hand to build a flyable reactor of the same materials as HTRE-3 and similar in physical size.” Despite the fact that HTRE-3 didn’t produce the power that would have been needed for flight, that was mainly because it was not an optimized design; it was designed simply as a research reactor, to prove the concepts needed for a flight article. At the end of the HTRE run the probability of flying a reactor seemed high. The test runs showed that a reactor using the same materials as HTRE-3, and which could power a gas-turbine powerplant, could have been built at that time.

In april 1959 GE stated that studies indicated that the basic XMA-1 power plant was suitable for the CAMAL mission. Studies by both Convair and Lockheed on the CAMAL airplane based on design objectives for the XMA-1C (Expected to use an advance fuel element of iron-chrome-aluminum or ceramic material. The turbine inlet temperature was expected to be 1700 degrees F, producing about 42 000 pounds of thrust at static sea level conditions.) power plant indicated the possibility of attaining such an airplane. GE proposed that, after the airplane had been checked out on chemical power plants, the XMA-1A (Planned to operate with nichrome fuel elements at a turbine inlet temperature of about 1500 degrees F, producing about 26 000 poundss of thrust at static sea level conditions) would first be tested, to be followed by testing of the XMA-1C power plant. As a consequence of a program reorientation in July 1959, work on the XMA-1A powerplant was canceled in August 1959. – ATSForum

See Dreams of Nuclear Flight for available declassified info. Here is a summary from a few different Wikipedia entries:

The X211, also known as the J87, was a nuclear-powered turbojet engine designed to power the proposed WS-125 long-range bomber. The program was started in 1955 in conjunction with Convair for a joint engine/airframe proposal for the WS-125. It was one of two nuclear-powered gas turbine projects undertaken by GE, the other one being the X39 project. The X211 was a relatively large turbojet engine of straight conventional layout, save for the combustion chamber being replaced with a heat exchanger. It featured included variable-stator compressors and an afterburner. A single nuclear reactor was intended to supply heat to two X211 engines. In 1956, the USAF decided that the proposed WS-125 bomber was unfeasible as an operational strategic aircraft. In spite of this, the X211 program was continued for another 3 years, albeit with no target application. It was finally terminated in mid-1959, and by 1961, all funding for nuclear propulsion was canceled.

In the 1950s, interest in the development of nuclear-powered aircraft led GE to experiment with two nuclear-powered gas turbine designs, one based on the J47, and another new and much larger engine called the X211. The design based on the J47 became the X39 program. This system consisted of two modified J47 engines which, instead of combusting jet fuel, received their heated, compressed air from a heat exchanger that was part of the Heat Transfer Reactor Experiment (HTRE) reactor. The X-39 was successfully operated in conjunction with three different reactors, the HTRE-1, HTRE-2 and HTRE-3. Had the program not been cancelled, these engines would have been used to power the proposed Convair X-6.

The X-6 would have been powered by General Electric X-39 engines, utilizing a P-1 reactor.^[4] In a nuclear jet engine, the reactor core was used as a heat source for the turbine’s air flow, instead of burning jet fuel. One disadvantage to the design is that since the airflow through the engine was used to cool the reactor, this airflow had to be maintained even after the aircraft landed and parked.^[3] GE built two prototype engines, which can be seen outside the Experimental Breeder Reactor I in Arco, Idaho.^[1]

A large, 350-foot (106.7 meter-) wide hangar was built at Test Area North, part of the National Reactor Testing Station (now part of the Idaho National Laboratory), Monteview, Idaho to house the X-6 project, but the project was cancelled before the planned 15000-foot (4572m) runway was built. The length was necessitated by the expected weight of the nuclear-powered aircraft. … In the 1960s, the Soviet Union’s Tupolev design bureau conducted a similar experiment using a Tupolev Tu-119, which was a Tu-95 bomber modified to carry an operational reactor.

What about shielding? From Aviation-History:

After establishing the parameters for the power plant and the transfer mechanism, engineers commenced work on the shielding for the crew and aircraft avionic systems. Initial plans called for the shielding of the reactor by massive layers of cadmium, paraffin wax, beryllium oxide, and steel. The idea behind this setting was that the more protection the reactor have, the less shielding the crew cabin would require. Technically, this was a sound approach, but in a rapidly functioning environment such as an aircraft setting, this shielding proved to be ineffective. For this reason it was decided to implement what is known as Shadow Shielding Concept. In shadow shielding, the layers of protection would be equally divided between the reactor and the crew cabin. Shadow Shielding would also provide a more robust protection for the aircraft’s avionics systems. An added plus from the implementation of this system was the reduction in the weight of the aircraft due to the distribution of the shield.

Having tackled the reactor, transfer mechanism, and shielding problems, the program moved it to the aircraft design stage. By late 1951, the program was heavily involved in the acquisition of a test-bed type aircraft for the initial trials of the configuration. The only proven airframe large enough to carry the massive reactor and Heat Transfer system was the Convair’s B-36 Peacekeeper Bomber. The Peacemaker started to enter front line service with the U.S. Air Force in late 1948 and at the time of the nuclear powered program, was the Strategic Air Command (SAC) main nuclear deterrent platform. The B-36 was indeed massive. The dimensions are impressive even today. A wingspan of 230 ft, a length of 162 ft 1in, high of 46 ft 8in, and a wind area of 4,772sq ft. This bomber maximum take-off weight was an amazing 410,000 lbs—which is why the program managers selected the B-36. A service ceiling of 39,900 ft and a climb rate of 2,220 ft per minute were also pluses in the selection process. Once the testing aircraft had been identified, the next phase would commence at once—the conversion of the B-36 into an experimental aircraft. The main modification made to the original B-36 airframe was on the nose cone section. The original crew and avionics cabin was replaced by a massive 11 ton structure lined with lead, and rubber. Water tanks were also placed in the aft section of the frame to absorb any escaping radiation. …

The NB-36 now had four GE J47 nuclear converted piston engines generating 3,800 hp augmented by four 23.13 kn turbojets generating 5,200 lbs of thrust. Each of the engines utilized the Direct-Cycle Configuration for power conversion. The NB-36 was designed from the beginning, to be propelled to the air with a conventional chemical mixture, and then the crew would switch on the reactor after achieving the necessary heat requirements on its core. On landing approaches, the aircraft would switch back to chemical mixture. This procedure was implemented in order to minimize the possibility of a major radiation leak in case of a crash landing.   – ah

How small and safe could we make a nuclear reactor?

Toshiba has designs for a micro nuclear reactor that generates 200 kw for 40 years

The new reactor, which is only 20 feet by 6 feet, could change everything for small remote communities, small businesses or even a group of neighbors who are fed up with the power companies and want more control over their energy needs.

The 200 kilowatt Toshiba designed reactor is engineered to be fail-safe and totally automatic and will not overheat. Unlike traditional nuclear reactors the new micro reactor uses no control rods to initiate the reaction. The new revolutionary technology uses reservoirs of liquid lithium-6, an isotope that is effective at absorbing neutrons. The Lithium-6 reservoirs are connected to a vertical tube that fits into the reactor core. The whole whole process is self sustaining and can last for up to 40 years, producing electricity for only 5 cents per kilowatt hour, about half the cost of grid energy. It has dimensions of 20 feet by 6 feet. Toshiba expects to install the first reactor in Japan in 2008 and to begin marketing the new system in Europe and America in 2009.

Perfect for all your underground base needs. Is it possible that research continued secretly?

New oral agents may prevent radiation injury. Just use vitamin C?

Researchers from Boston University School of Medicine (BUSM) and collaborators have discovered and analyzed several new compounds, collectively called the ”EUK-400 series,” which could someday be used to prevent radiation-induced injuries to kidneys, lungs, skin, intestinal tract and brains of radiological terrorism victims. The findings, which appear in the June issue of the Journal of Biological Inorganic Chemistry, describe new agents which can be given orally in pill form, which would more expedient in an emergency situation.

These agents are novel synthetic “antioxidants” that protect tissues against the kind of damage caused by agents such as “free radicals.” Free radicals, and similar toxic byproducts formed in the body, are implicated in many different types of tissue injury, including those caused by radiation exposure. Often, this kind of injury occurs months to years after radiation exposure. The BUSM researchers and their colleagues are developing agents that prevent injury even when given after the radiation exposure.

This paper describes a newer class of compounds, the ”EUK-400 series,” that are designed to be given as a pill. According to the researchers, experiments described in their paper prove that these agents are orally active. They also show that the new agents have several desirable “antioxidant” activities, and protect cells in a “cell death” model.

These same BUSM researchers and collaborators had previously discovered novel synthetic antioxidants that effectively mitigate radiation injuries, but had to be given by injection. “

via New oral agents may prevent injury after radiation exposure.

Drug companies hate that they can’t patent Vitamin C.

Doctors are to begin clinical trials to investigate whether cancer patients should be given huge doses of vitamin C alongside conventional drugs after research suggested the vitamin could dramatically boost survival rates.

High doses of vitamin C reduced the growth of aggressive tumours by between 41% and 53% when injected into mice affected by the disease, researchers found. The vitamin was injected directly into the bloodstream because animals, including humans, naturally limit how much vitamin C they absorb from food. – guarduk

Until a genetic mutation in our past, our bodies used to make Vitamin C from sugar.

Like plants, most mammals (with the exception of humans and guinea pigs) make their ascorbic acid from glucose and can make glucose from ascorbic acid. Some primates, remote ancestors of humans, underwent a genetic mutation about 40-45 million years ago and haven’t been able to make “vitamin C” since. Therefore living humans need nowadays to get all “vitamin C” from food. Some scientists think that the loss of human ability to make “vitamin C” may have caused Homo sapiens’ rapid evolution into modern man. – wiki

Uranium Found on the Moon

Uranium exists on the moon, according to new data from a Japanese spacecraft.

The findings are the first conclusive evidence for the presence of the radioactive element in lunar dirt, the researchers said. They announced the discovery recently at the 40th Lunar and Planetary Conference and at the Proceedings of the International Workshop Advances in Cosmic Ray Science.

The revelation suggests that nuclear power plants could be built on the moon, or even that Earth’s satellite could serve as a mining source for uranium needed back home.

The Japanese Kaguya spacecraft, which was launched in 2007, detected uranium with a gamma-ray spectrometer. Scientists are using the instrument to create maps of the moon’s surface composition, showing the presence of thorium, potassium, oxygen, magnesium, silicon, calcium, titanium and iron.

“We’ve already gotten uranium results, which have never been reported before,” said Robert Reedy, a senior scientist at the Tucson-based Planetary Science Institute, and a member of the Kaguya science team. “We’re getting more new elements and refining and confirming results found on the old maps.”

The findings could help decide where to build future lunar colonies, since manned outposts will need energy, and could potentially derive it from nuclear power plants.

Furthermore, since uranium supplies on Earth are scarce, mining uranium on the moon to satisfy our energy needs at home could prove lucrative.

Kaguya, officially named SELENE (“Selenological and Engineering Explorer”), crashed into the lunar surface at the end of its mission on June 10.

via Uranium Found on the Moon – Yahoo! News.

Nuclear nations rush to lock in uranium deals

A global shift toward nuclear power is prompting countries to rush to lock in long-term access to tight supplies of uranium, and China and India look to be the next players to get in on the action.

A tie-up between Rosatom, the Russian state-owned producer, Rosatom and Canada-based miner Uranium One announced this week is just the latest in a series of moves on the part of Asian and European countries to lock in uranium supply to fuel construction of dozens of new reactors over the next decade.

“I think increasingly the supply of reactors is being tied to security of supply of nuclear fuel,” said Divya Reddy, an energy analyst with the Eurasia Group in Washington.

Rosatom secured a 17 percent stake in Uranium One and a long-term supply deal in exchange for a half stake in the Karatau mine in Kazakhstan.

Uranium One is also trying to close a C$270 million ($240 million) 20 percent share sale and supply agreement with Japan’s Toshiba Corp, Toyko Electric Power Co, and Japan Bank for international Cooperation, while uranium miner Denison Mines recently agreed to sell 20 percent of itself to Korea Electric Power Corp.

Reddy sees more activity from Russia as it strives to expand its influence in the nuclear industry, but said the most likely sources of demand in the longer run will come from Asia, including India, which last year signed a deal ending a three-decade ban on nuclear trade with the United States.

“There is definitely growth in demand from developing countries. China would be the biggest market, India probably next,” she said.

China, with the most ambitious nuclear power expansion plans, has been in talks with top uranium miner Cameco about a potential supply deal, a company spokesman confirmed.

Australia is also mulling selling uranium from BHP Billiton’s Olympic Dam mine to China, provided it is not used in Beijing’s weapons program.

100 NEW REACTORS

Led by China, India and Russia, more than 100 new reactors will be built over the next decade, Cameco estimates, all part of a global push to reduce dependence on greenhouse gas-producing power sources such as coal.

With new reactors expected to be larger on average than the 426 currently in operation, generating capacity would grow by 28 percent, the company says.

“Over 10 years, the demand for uranium will definitely continue to rise, and there will be a need for new mines and new solutions,” said Mike Goldenberg, director of nuclear fuel markets at New York-based Evolution Markets.

Meanwhile, state-run Russian and Kazakh nuclear concerns have been busy signing deals with countries such as China and Japan to export nuclear industry and technology.

via Nuclear nations rush to lock in uranium deals | Green Business | Reuters.