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Comment Re: If a motor is required to hold up the rods (Score 1) 168

Second, assume that you haven't thought up some new and novel failure scenario in the 30 minutes you've been thinking about it today than the engineers who have been designing and simulating for _years_.

These SMRs are specifically designed so that when things go wrong they fail safe, the reaction stops, no meltdown.

1) It is a conceit to believe all the edge cases have been considered.

2) There is also the "It is difficult to get a man to understand something when his salary depends on his not understanding it" factor.

"No engineer is going to intentionally-" "Morton Thiokol. Fukushima. 737-Max."

"The NuScale reactor has 1/20 of the nuclear fuel of a large scale reactor. Its small decay heat, inherent stability, and reactor physics eliminates fuel damage in all design basis events including those with failure of all control rods to insert. For beyond design basis events, radiation from fuel damage is below safe limits at the plant site boundary." The reactor can't fail in the same way the reactor at Fukushima Daiichi did. In the accident in Japan, the earthquake caused that reactor to successfully shut down. However the Tsunami cut off site power and swept away the backup diesel generators (backup onsite power). There was not sufficient batter power available to cool the reactor decay heat long enough for power to be restored. They did not have backup offsite generators near enough to fly in as is now required. If they had not suffered station black out the reactor would have been cooled long enough to go to cold shutdown. The SMR design is significantly smaller in size and power density, This means that if the reactor is shutdown but loses power cooling pump, the small size of the core reduces the total heat load and even with loss of offsite power the decay heat can be removed. If the reactor fails to shut down (partial or fully stuck control rods) the core inventory is small enough that any radioactive release would fall below regulatory limits at the site boundary.

Comment Re:The Humanure Handbook (Score 1) 413

Did you read the article? "He also found that slum dwellers there collected their excrement in a plastic bag and disposed of it by flinging it, calling it a 'flyaway toilet' or a 'helicopter toilet.'... ...He plans to sell it for about 2 or 3 cents — comparable to the cost of an ordinary plastic bag." The inventor saw a problem and came up with a solution.

Comment Re:Math cannot exist before wind. (Score 1) 221

yes, but the time in which a radioactive isotope is reduced by half is in terms of a decay constant divided by ln(2). Which I am pretty sure is irrational and involves e \snark. The only time you have that nice integer decay curve is if the decay constant is ln(2)....so I think JD's point stands.
Earth

Scientists Reconstruct Millennium's Coldest Winter 290

Ponca City, We love you writes "In England they called it the Great Frost, while in France it entered legend as Le Grand Hiver, three months of deadly cold that fell over Europe in 1709 ushering in a year of famine and food riots. Livestock died from cold in their barns, chicken's combs froze and fell off, trees exploded and travelers froze to death on the roads. It was the coldest winter in 500 years with temperatures as much as 7 degrees C below the average for 20th-century Europe. Now as part of the European Union's Millennium Project, Scientists are aiming to reconstruct the past 1000 years of Europe's climate using a combination of direct measurements, proxy indicators of temperature such as tree rings and ice cores, and data gleaned from historical documents."

Comment Re:Claims to Destroy TRU Waste (Score 1) 432

This only partly correct. TRU stands for transuranic waste. TRU is explicitly the waste produced from absorption of a neutron by a uranium isotope. The "excited" isotope then beta decays to Neptunium which then either decays again or absorbs a second neutron and either fissions of becomes excited and decays again. This process occurs billions of times in a reactor which is why you can accumulate isotopes as high as Californium in measurable quantities. Any isotope with a higher atomic number is considered TRU. You seem have fission products confused with the actinides higher than uranium. Fission products (FP) tend to be more radioactive which means that they decay rapidly (milli-seconds to days) with the exception of a fewer longer lived FP. For long term storage TRU becomes the main problem because the half-lives for decay are sufficiently longer. The idea behind this system is twofold:
1) Use an intense fast (fast meaning high energy) neutron flux produced from fusion to induce more fissions versus captures in the transuranic elements (TRU) to produce fission products that will decay rapidly and be less of a long term waste issue.
2) Allow for a use of fusion technology that will be a net energy producer. This is possible because the neutrons which escape the fusion process and are normally a loss will now produce fissions (at least some fraction of them will) which will hopefully produce enough energy to overcome the normal losses due to leakage (gamma rays, neutrinos, neutrons, ect).

Nuclear waste IS broken into two main categories LLW and HLW. Pretty much all fission products and transuranic elements are initially put in the HLW catagory since both groups of isotopes tend to be neutron heavy and want to decay. Of course /nuclear engr

Comment Re:20 year off == 20 good funding years (Score 1) 220

An intermediate step would involve surrounding the Z-pinch machine with a subcritical fission chamber. Then you could use the pulsed neutron source from the Z-pinch to drive the fission and breed tritium. Then you could use the heat produced from both fusion/fission to generate electricity. As an added bonus you could fuel your subcritical chamber with transuranic "waste" from the current light water reactors. The fuel could be kept as a fluid which would eliminate fuel fabrication cost and the issues associated with minor actinide fuels.

At a pulse rate of .1 Hz you could generate a good amount of power and burn up alot of transuranics that won't have to be stored at Yucca Mountain.

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