[Nuclear energy] is well-nigh inexhaustible, if only it could be tapped. SirArthur Stanley Eddington (1920)
(2011-09-07) Henri Becquerel's great experimental discovery.
It is important to observe that this phenomenon cannot be attributedto the luminous radiation emitted by phosphorescence. Henri Becquerel(1852-1908; X1872;Nobel 1903)
Although that early discovery was duly heralded as major at the time (1857) the World was apparently not quite ready for it yet... By the time of Becquerel's own discovery (1896) the previous work of Niépce de Saint-Victor had apparently been all but forgotten...
Curiously enough, one of the few noteworthy physicists who did notice in due time was Becquerel's own father! Edmond Becquerel (1820-1891)fully discussed the future discovery of his son in a book he published in 1868 (La lumière, ses causes et ses effets). At the time, the younger Becquerel was 16 and curious. It's hard to believe he never read the book of his father.
(2011-09-08) New elements discovered by Pierre & Marie Curie.
(2017-06-28) Rutherford named 3 types of ionizing radiation.
Together at McGill University, Rutherford and Soddy correctly explained that the atoms of a radioactive elementundergo a spontaneous transmutattion into one or more other elements.
The decay rate for a given atomic species depends only on the number of atoms present. As each microscopic decay destroys one atom, the activity of that particularreaction decreases exponentially with time.
However, such transmutations may well produce other radioactive substanceswhich decay at their own rate into other species. Therefore, the total radioactivity of a given sample endsup reflecting several different types of decays and its variation overtime can be complicated.
(2011-01-19) This experiment was first conducted byHans Geiger (1882-1945)andErnest Marsden (1889-1970)under the supervision of Rutherford.
It was almost as incredible as if you fired a 15-inch shell ata piece of tissue paper and it came back and hit you. Ernest Rutherford (1871-1937)
TheGeiger-Marsdenexperiment (1909) was conducted while Hans Geiger was a student of RutherfordatManchester. Ernest Marsden was still an undergraduate student there (he was a New-Zealander, like Rutherford).
(Yahoo!2011-01-16) How close can those -particles approach another polonium nucleus?
Using unabbreviated notations, the nuclear decay involved can be written:
Po
Pb
2 124
+
He
+ 5.4075 MeV
The -particle being the bare nucleusof helium-4 (doubly-ionized atom of helium-4) the above is commonly written with more compact notations:
Po
Pb
+
+ 5.4075 MeV
Table of Relevant (Neutral) Isotopes
Element
A
Atomic weight (u)
Half-life
Decay
%
Q-value (keV)
82
Pb
206
205.974465 278
84
Po
210
209.982873 673
138.376(2) d
100
5407.46(7)
In the main, this may be treatednonrelativistically. As the initial polonium atom is at rest, the two outgoing particles haveopposite momenta and thus share the available total energy in inverse proportionof their masses. So, the recoiling lead atom gets 1.9% of it and the alpha particleretains 98.1%.
(2011-01-27) The Q-value energy of a nuclear reaction balances the change in mass.
There isn't the slightest indication that energy will ever beobtainable from the atom. [Oops! 1932] Albert Einstein (1879-1955;Nobel 1921)
(2011-01-21) Heavy radioactive nuclei decay in the following five standard modes :
Decay :
The alpha-decay of an atom is the emission of an -particle from its nucleus (an Helium-4 nucleus consists of 2 protons and 2 neutrons). The mass number (A) is decreased by 4 units;the atomic number (Z) is decreased by 2 units. With a negligible error (due to the differences in electronic bindingenergies for helium-4 versus other elements), the products of-decay havea mass not less than the combined mass of a neutral helium-4 atom (namely 4.002603254 u) and the (neutral) isotope of the element two steps down witha mass number four units down. This implies an inequality among tabulatedmasses of the istopes which is a necessary (and almost sufficient) condition for -decay to occur. Translated in terms of energy, the positive difference between theaforementioned masses is the so-called Q-value for the -decay reaction.
Decay :
decay is commonly abbreviated EC("electron capture") in English texts. It consists in the capture of an orbital electron (and emission of a neutrino). One proton of the nucleus turns into a neutron;the mass number (A) does not change; the atomic number (Z) is decreased by one. Besides a neutrino, whose energy can be arbitrarily low, decay producesonly a neutral atom of the previous element (more precisely, the isotopeof that element which has the same mass number as the isotope whose decayis being considered). Thus, an atom can undergo decayonly if it is heavier than the corresponding isotope of the previous element.
+ Decay :
+ decay consistsin the emission of a positron (and a neutrino). One proton of the nucleus turns into a neutron; the mass number (A) doesnot change; the atomic number (Z) is decreased by one. The decay produces the same nuclear result as decay buta positron is radiated away and an additional electronremains in the vicinity of the nucleus (the atom produced is a negativeion instead of a neutral atom for +).
The binding energy of an electron is less than a few electron-volts;(1 eV being about 0.00000000107 u). If we neglect that,the above means that + decaycan only occur for an atom whose mass exceeds that of the correspondingisotope of the previous element by at leasttwo electron masses (i.e. 0.001097 u).
- Decay :
- decay consists in the emissionof an electron (and an antineutrino). It used to be known simply as " decay"before the discovery of the positron (1932). One neutron of the nucleus turns into a proton; the mass number (A) doesnot change; the atomic number (Z) is increased by one. Besides the antineutrino, whose energy can be arbitrarily small,- decayproduces only a positive ion and an electron whose combined mass is notless than that of a neutral atom.
Thus, - decay can occur as soonas the decaying atom is heavier than the corresponding isotopeof the next element.
- : There are some (very) long lived radioisotopes like Tellurium-128 orTellurium-130 for which a single - decayis impossible but for which near-simultaneous double- decays(2-) are allowed because the atom is heavierthan the corresponding isotope two elements up. Thus, the 2- decay ofTe-128 (resp. Te-130) into Xe-128 (resp. Te-130) is rare butpossible, whereas the - decay ofTellurium into Iodine is forbidden. Other nuclides for which the same remark applies include Ca-48, Ge-76, Mo-100,Xe-136, Ne-150...
Isomeric Transition :
Isomeric Transition (IT) is the name given to the decay of a long-livedexcited state of the nucleus into an isomeric state of lower energy (usually, but not always, the ground state). Such long-lived metastable statesare normally marked with the suffix "m" or, if there are several, "m1", "m2", "m3", etc. During such a decay, the extra energy and the extra spin (a whole numberofspin quanta) is carried away by gamma-ray photons.
(2011-01-21) Successive decay products of a heavy nucleus stay in one of four series.
Since the above standard decay modes either decrease the mass number (A) by 4 units or leave it unchanged, there are4 standard radioactive families or series. The mass number modulo 4 is characteristic of each series.
Three of those families are natural ones whichstart with a long-lived parent and end with a stable isotope of lead. Glenn T. Seaborg was instrumental in establishing artificially the fourth series,which was extinct : With a half-life of only 2.14 million years, the parent of that series (Neptunium-237) has notmaintained a native presence on Earth. Neither has any other member of the Neptunium series, except for the [two] final one[s]: Bi-209 [& Tl-205].
years matched predictions around 4.6 years, based ontabulated masses and energies that have since been revised because of this discovery.
(2011-01-21) Lighter isotopes commonly decay in nonstandard modes.
One reason why theabove concept of radioactive seriesis of little or no use for lighter elements is that their radioactive isotopesmay decay in nonstandard modes which need not preservethe mass numbermodulo 4.
Such modes include the spontaneous emission of a proton or a neutron,spontaneous fission into two nuclei [both bigger thanan alpha particle] or spallation intothree or more fragments.
(2011-09-07) The simplest device to detect ionizing radiation and quantifyactivity.
(2011-09-07) Measuring and tallying the energy of individual gamma rays.
A scintillator crystal (e.g., sodium iodide doped with thallium) produces a flash of visible lightwhose intensity is proportional to the energy of the incoming gamma photon.
(2011-08-26) The apparent size of the target depends on the speed of the projectile.
(2011-02-02) Bombarding stable nuclides with neutrons can make them radioactive.
(2011-02-02) Neutron-induced decays release neutrons that induce further decays
(2011-02-02) The smallest mass that can cause a runaway chain reaction.
TheAblenuclear test (3.5 miles off Bikini Island, on July 1, 1946) was the fourth nuclear explosion ever (the first three were Trinity, Hiroshima and Nagasaki). Although the test itself didn't cause any casualties, the plutonium core involved (dubbed the Demon core) has previously claimed two lives...
(2011-10-16) Nuclear fusion can release much more energy than fission devices.
Alpha (Yahoo!2011-01-03) In a dead organism, carbon-14 decays with a half-life of 5730 years.
C
N
+
e
+ 156.46 keV
The above decay occurs forradiocarbon everywhere, including in the carbon dioxide of the air. However, the concentration of carbon-14 in the atmosphere remains essentially constantbecause it is replenished by the following action on nitrogen of neutrons that originatefrom cosmic rays:
n +
N
C
+
p
+ 625.87 keV
All told, the atmospheric concentration of radiocarbon remains fairly constantbut it may vary for several reasonsthat influence the above production of radio-carbon. Those factors, listed by increasing order of severity, include:
Radiocarbon is primarily produced in the upper atmosphere where itgets oxidized by oxygen. Radioactive carbon dioxide thendiffuses down below (which means that the concentration of radiocarbonvaries a little bit with altitude).
The bombardment by neutrons is very sensitive to cosmic circumstances whichmay vary over time. This results in some noise which limits the precision of carbon dating for relativelyyoung samples, unless some calibration isdone using samples of dead things whose history is precisely known by other means.
When atmospheric nuclear tests where still allowed,there were times when the concentration of radiocarbon was twice ashigh in some locations of the Northern Hemisphere compared toreference points in the Southern Hemisphere. (Mixing of air through thehorse latitudescan be particularly slow at times.) In the distant future, dead plants that grew in the wrong places during that dark periodmay appear thousands of years too young if this effect is not taken into account.
... / ...
Table of Relevant Isotopes (neutral elements, unless otherwise specified)
Spencer (Yahoo!2007-10-27) When two deuterons come together in fusion, mass is lost. Wassup?
In the fusion of two light nuclei (like deuterons) the resulting nucleus hasa mass which is less than the sum of the masses of the reactants.
The missing mass is converted to energy. The fusion yields a nucleus in an excited state which can eitherrelease that extra energy directly as gamma rays or split into something else. For example:
When two new particles are produced like this,the final release of energy is normally split between them as kinetic energyin inverse proportion of their respective masses. In this example, as the helion has about 3 times the mass of the neutron,it gets 25% (817 keV) and the neutron 75% (2.45 MeV).
Fusing heavier elements (i.e., elements heavier than Fe=iron) requires an input of energy,while the splitting of an heavy nucleus into several lighter pieces (fission) releases energy. For example fission of a uranium nucleus releases energy.
The fusion of heavy nuclei into heavier ones is only possible in very violent events (like the supernova explosion of a star) because there is extra energy floating around which can be absorbed in the process. This is how all elements heavier than iron were once synthesized from lighter elements (mostly hydrogen and helium) of which the early universe was made of.
(2011-08-20) What powers the Sun and all stars colder than 15 000 000 K.
The first and most critical stage is the fusion of two protons toproduce a deuterium nucleus (deuteron) as summarized by this nuclear reaction :
p+ + p+2D+ + e+ + e + 0.42 Mev
That was first proposed in 1937, by George Gamow (1904-1968) and Carl Friedrich von Weizsäcker (1912-2007). This reaction can be dissected into two successive steps:
1. Two protons fuse by quantum tuneling (classically, kinetic energies in the coreof a smallish star wouldn't overcome theCoulomb repulsion).
p+ + p+ + 1.25 Mev 2He++
The diproton so produced (Helium-2 nucleus) is very unstable (half-life is much less than a nanosecond). So, the protons will readily separate and, as the above notation suggests, what we have is like an equilibrium between many protons and a few diproton in a thermal bath of photons. However, in less than 0.01% of the cases, the diprotondecays into deuterium instead, which is the advertised second step :
2. One bound proton decays into a neutron by + Decay, emittinga positron, a neutrino and more thermal energy than previously borrowed:
2He++2D+ + e+ + e + 1.67 Mev
That one-way trip is a weak-interaction process which takes placeon a longer time scale than the previous one.
The proton-proton cycle :
The above production of deuterium is just the beginning of a chain of reactionswhose net result is the production of Helium-4 from protons, now known as the proton-proton cycle.
(2018-05-23) (Hans Bethe, 1938) Bethe's CNO cycle provides 7% of the Sun's power output.
(2018-05-23) (Fred Hoyle, 1952) A coincidence makes Carbon and Oxygen abundant in the Universe.
(2011-08-15) Igniting fusion by heating a magnetically-confined plasma.
For two positively charged atomic nuclei to fuse, they must come closeenough to each other for the attractive nuclear forces toovercome their electric repulsion. This can only happen if their relative speedexceeds a certain threshold, which can be measured equivalentlyeither in terms of energy or temperature. The latter is called the ignition temperature.
Temperature (K) = 11604.5 (Charges on the particle) (Voltage)
The lowest known ignition temperature (4.5 7 K,or about 4 keV) is for the fusion of deuterium and tritium (this fusion cannot occur in a natural star unless some tritium is producedby a prior process with a higher ignition temperature). As this "D-T fusion" seemed easiest to ignite,it became the focus of all Tokamak experiments.
The energy of 17.6 MeV isshared between the particlesinversely as their masses: 20% (3.5 MeV) for 4He++ and 80% (14.1 MeV) for the neutron. In a neutron-rich environment, the (rare) tritium can actually beregenerated from natural or enriched lithium through the following reactions, so thatthe only fuels consumed are deuterium and lithium (the only exhaust being helium).
In a magnetically confined plasma, the charged helium nuclei (alpha particles) remain in the plasma. Neutrons, on the other hand, ignore the magnetic confinement andescape into the blanket material around the reactor, which gets hot by absorbing them. Useful energy can be recovered as heat byrunning a cooling fluid through that blanket.
The net result of the above equations is that the number of neutronswhich end up in the blanket is exactly equal to the number oftritium-7 consumer from the fuel. It's thus essential for the isotipic mix of the duel to containa substantial proportion of lithium-7. (Natural lithium contains 92.5% of lithium-7).
Adaviel (Yahoo!2010-01-24) At what temperature does nuclear fusion ignite? Is cold fusion possible?
18 000 000 K
(2011-08-15) A well-established way to achieve nuclear fusion on a tabletop.
The design presented below is extremely simple and works very well.
The actual construction involves substantial engineering challenges. However, those have not stopped dozens ofamateurs (including a few high-school students) from building homemade nuclear fusion reactors...
The core is just a spherical cavity containing deuteriumunder a very low pressure between 5 and 20 microns. Prior to receiving the deuterium, the cavity is evacuated down to 0.001 or 0.0001 microns (another possibility might be to flush the cavitywith deuterium several times using less extreme pumping).
Hg). Both definitions are used interchangeablyin practice (although the latter is preferred) since both specify almost the same pressure. Thecorrect equivalence is precisely:
1 Hg
= 0.133322387415 Pa (exactly)
= 1.000000142466321243523316... mTorr
Inside the cavity are two concentric spherical electrodes. The wall of the cavity can serve as the outer electrode (it can be electrically grounded for safety). The inner electrode, on the other hand, is kept at a large negative potential -U of -10 000 V or -30 000 V.
That inner grid must consists of a loose mesh of wire. It is thus fairlytransparent to the positive ions that it attracts (which will gothrough it most of the time, at substantial speed).
Elmore-Tuck-Watson electron accelerator :
Farnsworth Labs (later, "ITT Philo Farnsworth Research Corporation") consisted of never more than 6 engineers working on-site at thePontiac St.television factory in Fort Wayne, Indiana, until ITT stopped funding the research in 1967. Theoriginal team (1959) working on fusors included:
Rear admiral Frederick R. Furth(1901-1995). VP of ITT (R&D).
In 1998, Richard Hull, the firstamateur toachieve nuclear fusion did meet with all four living members of that original team (Hirsch, Meeks, Haak and Blasing). Hull did it again with Paul Schatzkin around 2004. Hull and Schatzkin are now coordinating the efforts to keepalive among amateurs the practical knowledge gathered in that era, as explainedbelow.
(2011-08-15) The brainchild of the late Dr.Robert W. Bussard (1928-2007).
On 2006-11-09, Robert Bussard gave an inspirationalGoogle Tech Talkon the fusion reactor that he had been developping since 1987, with Navy funding,at his own company (EMC2) whereTom Ligon had assisted him for 5 years. Bussard passed away only 11 months later, at the age of 79. However, his Google talk was instrumental in getting his company renewed Navy backinga few weeks before his death. This allowed research at EMC2 togo on,with a team of 5 people led byDr. RichardNebel who was on leave fromLos Alamos.
Rick Nebel retired in November 2010 and was suceeded by 41-year-old Jaeyoung Park who gave up his position at Los Alamos to focus on the project. As ofMay 2011,EMC2 employs 8 or 9 staff members interacting with about two dozen external consultants.
If/when it becomes practical to use nuclear fusion to generate energy,neutron radiation would become a nuisance. Aneutronic fusionwould be preferred, possibly usingBoron-11in a 500 keV reaction, known as "Proton Boron-11" (p-B11) and heralded as the Holy Grail of fusion :
11B + 1H
12C + 15.957 MeV
8Be + 4He + 8.590 MeV
34He + 8.682 MeV
A large part of the kinetic energy of the alpha particles so produced (without any residue or harmful radiation) could be converted directlyinto electricity.
Unfortunately, theoreticalarguments presented by Todd H. Rider in his doctoral dissertation atMIT (1995) strongly indicate that any plasma outside of thermal equilibriumcannot generate net fusion power because ofBremsstrahlung losses (even with gridless designs like the Polywell machines). This applies to all known clean nuclear fuels and, most probably, toother fuels as well. Allowing the plasma to thermalize seemsto make matters only worse. Here's how Rider saw fit to start his dissertation:
Apparently, Bussard never considered that the Bremsstrahlung issue could bea fundamental limitation and kept arguing that the power output of large Polywell machineswould scale as the seventh power of their linear size...
(2011-08-13) Amateur nuclear physics is a hobby that may puzzle the general public.
From natural radioactivity to fusors...
Here are a few samples of the many videos (all are nice, some are great ) of Illy Sommer ("bionerd23") a self-described radiophile from Berlin, Germany (b. 1984).
One of the above topics is the homemade fusor (i.e., fusion reactor) built by Jon Rosenstiel of Anaheim, California. Jon's fusor holds the record inamateurnuclear fusion, with more than 10 million neutrons per second. Such devices are arguably the most advanced type of nuclear contraptionsthat have been successfully duplicated by independent amateurs.
The amateur fusion movement began in 1997 when Tom Ligon,the assistant ofRobert Bussard, decided tostir up interest in nuclear fusion among the Tesla Coil Builders Of Richmond (TCBOR) at a Teslathon organized by Richard Hull in Richmond, VA. In a matter of weeks, Hull had built his own fusor and other amateurs weren't far behind...
With Paul Schatzkin ("The Perfesser") Richard Hull now runs fusor.net, where all fusioneers congregate (including Tom Ligon). Hull maintains alistof known experimenters at various stages of their own fusor projects :
Scroungers who have declared their intentions to gather components.
Plasma Club members have obtained preliminary functionality.
Members of the Neutron Club have achieved fusion and measured it.
As of June 2013,about 50 hobbyists have reached that last stage (dubbed Star in a Jar in some popular articles). They almost always use a plasma of deuterium as nuclear fuel in a traditionalFarnsworth-Hirsch Fusor,which can be built at low cost (albeit beyond Hull's low estimate of $50-$400).
According to the aforementioned records, Mark Suppes (who has worked as a Web designer for Gucci) became the 37-th hobbyist to achieve nuclear fusion,in 2010 (in a Brooklyn warehouse, at a cost of about $39000). Reportedly,Suppes was investigating Bussard'sPolywell design, but he apparently settledfor a standard Farnsworth-Hirsch fusor instead.
The amateurs are not even trying to produce the net output of energy thatcurrent researchis aiming for. Their fusors serve exclusively as artificial sources of neutrons based on deuterium-deuterium (D-D) fusion:
In 1966, a fusor built byBob Hirsh himselfput out 2 1010 neutrons/s using DT fusion. This is more than 1000 times thefigure of meritachieved by the best amateur devices with DD fusion.
(2011-08-08) Poor experiments attract more media attention than great investigations.
The best known case of radioactivity experimentations gone astray is surely that ofDavid Charles Hahn(born Oct. 30, 1976) who conducted misguided experiments on radioactivityin a potting shed at his mother's house, until 1994 (he was then a 17-year old boyscout whohad earned a merit badge for atomic energy in 1991 and had already attained the rank ofEagle Scout).
David C. Hahn became the subject of a 1998article in Harper's Magazine by Ken Silversteinand a subsequent best-selling book by the same author, entitled The Radioactive Boy Scout (2004).
After being discharged from the U.S. Navy, David Hahn returned to hishome state of Michigan, still obsessed with radioactivity. On August 1st 2007, at age 31, Hahn was arrested in Detroit for stealing 16smoke detectors (containingAmericium-241). His face was covered with open sores, hastily attributed to radiation exposure. No hazardous materials were found in Hahn's appartment.
Subsequently, Hahn was sentenced to a treatment facility where he had Internet accessand would make weird posts onarticlesabout his story, using the handle Thumper235 or Thumper23598 and signing: David Charles Hahn /Eagle Scout / Former U.S. Navy /Former U.S. Marine Corps (Retired) /Time Travel Institute Member /American Legion Member /Associates Of Applied Science /"The Radioactive Boyscout".
A Swedish rad-freak who made the news :
In May 2011, Richard Handl (a 31 year old unemployed man fromÄngelholm, southern Sweden) chronicled in his blog his own attempts at reproducing the misguided efforts of David Hahn. On 2011-05-20, he quoted some hilarioustongue-in-cheek recipe for building a "nuclear reactor"as if it had been some kind of inspirational documentary...
The very next day, Handl reported a"meltdown" [sic!]after trying to cook (on his stovetop) americium, radium and berylliumin 96% sulfuric acid,seemingly unaware of the dangerous propensity of concentrated sulfuric acidto burp when improperly heated. He had been fooling around with his samples of radioactive elements"to easier get them blended" [sic!] in the naive way mocked by the aforementioned spoof video...
Richard Handl alerted theSwedishRadiation Safety Authority himself to make sure he wasn't doing anything illegal... He was questioned by police, who confiscated his radioactive samples and his computer. He readily admitted that his experiments were crazy but (rightly) argued that they were"not so dangerous" (well, boiling concentrated sulfuric acidis just about as dangerous with or without radioactive samples in it).Following his arrest, Handl announced on his blog the "cancelation"of his project (2011-07-22). He clearlyenjoyedthe worldwidemedia attentionthat he attracted, starting with a 2011-08-02 FoxNews preliminary report (from aNewsCore story) and culminating with aBBC news interview on2011-08-04.
(2018-06-25) Theorized by Paul Kuroda (1956). Found by Francis Perrin in 1972.
In 1956, Paul Kuroda theorized that some natural deposits of uranium mighthave reached high enough concentrations for self-sustaining chain reactions during long periods of timein the past, if rich uranium deposits were flooded by groundwater (acting as a neutron moderator).
In 1972, this was confirmed by the French physicist Francis Perrin (1901-1992, son of the NobelistJean Perrin, 1870-1942). At the time, Francis Perrin was head of the CEA (the French agency responsible for nuclear energy) and he had to investigate anomalous resultsof routine mass-spectroscopy conducted, in May 1972, on uranium extracted from Gabon. The isotope ratios were similar to what's observed in uranium exposed to the core of a nuclear reactor. Perrin came to the conclusion that uranium from the Oklo mine had indeed been in a nuclear reactor, albeit a natural one...
On 25 September 1972, the CEA made its findings public and annouced that a nuclear reactorhad been operating on Earth about two billion years ago! Current estimates indicate that this happened about 1.7 billion years ago, running continously for a few hundred thousand years with an average output of nearly 100 kW which may have raised the local temperature by a few hundred degrees.
The mechanism which allowed the necessary high-concentration of uranium is directlylinked to the appearance of oxygen in theatmosphere of the Earth, about 1.8 billion years ago. In the presence of oxygen, the flow of groundwater could collect oxydized uranium from a substantialarea and allow it to concentrate at specific points.
This natural phenomenon has also given us a valuable clue for fundamental physics: The rate of neutron capture in certain transmutations (especially from Samarium-149 to samarium-150) is very sensitive to the value of Sommerfeld's fine-structure constant. The isotopic ratios observed at Oklo are consistent with the value of the constant which we observetoday, to a very high degree of precision. This severely restrict hypotheses which purport that some fundamental physical constantsmight vary over time.
(2018-08-08) Fast natural shutdown using Freeman Dyson's warm neutron principle.
In 1955, the entire field of nuclear reactors was declassified. Nuclear engineers could share their data at a conference in Genevawhose proceedings quickly became a bible for reactor physicists.
The required prompt negative temperature coefficient of reactivity exists with uranium-zirconium-hydride (UzrH) fuel rods.
(2018-10-26) CF) Muon-induced nuclear fusion can occur at room temperature.
The catalysis of nuclear reactions by muons was predicted theoretically in 1947, by Sir Frederick Charles Frank(1911-1998).
The same idea occurred a few years later to Yakov Zeldovich (1914-1987) and Andrei Sakharov (1921-1989) who were independently awarded the prestigious Lenin prize (in 1957 and 1956 respectively) when the actual phenomenon was duly confirmed in the West...
Muon-aided nuclear fusion was even achieved at very cold temperatures.
For a short time, this process was thought to promise a practical way to generate energy. This is what Luis Alvarez would later recollect about that (Adventures in Experimental Physics, 1975):
Mesons by Luis Alvarez et al. (1956-12-17). by F.C. Frank (1911-1998). Nature160, pp. 825-527, (1947-10-18).
(2019-08-30) Thermonuclear weapons nased on lithium deuteride (LiD).
The components of a thermonuclear weapon are seoarated by a classified aerogel called Fogbank. When the DOE had to refurbish legacy warheads, the production facility for Fogbank had been decommissioned and the know-how was all but gone. The stuff had to be virtually re-engineered from scratch, at great expense.
