Document wgvj7qZjnjZ8Z65QLEJq4zxzE

LIGHT-ATOM NUCLEI |H` Hydrogen 10 I HEAVY-ATOM NUCUI IA*lC RAtTlClES Pedicle Neutron Proton Electron Cborge 0 +1 --I WelgHfmoil Unlli! Appro* [tocl I I 1/1800 1,0019] 1.00751 On* lb of matter 'contolni 37] trillion trillion nu<looni (protom ond nau'rant) 334 i *? 4S9 (beyond hoilwm, nowlrom equal or etceed proton*) tlomool frelopa Thorium 90 143 133 Proteclinium *.Po,,` 91 140 331 Uranium iU>M 93 141 33) Uranium Uranium |UM* 93 143 333 iU,M 93 144 331 Neptunium iNp"' 93 146 339 Plutonium i.Pu*1* 94 148 339 Uranium 335 It tomplutly dotfood oi ,,U" in which 93, otomic numbor el ny ronium, indlcota* 93 proloni and 335 it numbor ol particle* {proton* plwi ntut'om) In tM* Itotopa. AI*o, 335 ) "moi* numbor" of gluon liotopa. Basic particles, variously linked, form atom structures. Some change. An atom U a tiny tolar system, with more then 99.9% of its masj in the central "sun" or nucleus. This nucleus consists of proton* and neutrons. Balancing each plus-charged pro* ton in the nucleus is a negatively charged, rapidly revolving, electron "planet." Thus the whole otom is electrically neu tral, although the nucleus is always positive. In atomic energy work we deal only with the nucleus and commonly use the word "atom" to mean the nucleus. Two numbers identify any atom. Thus iLi' means that any form of lithium has an atomic number of 3, because lithium atoms always have three protons. The mass number (7) Is the total number of nucleons (protons plus neutrons) In this particular isotope (form) of lithium. If a lithium isotope hod five neutrons its symbol would be Li*. Tables above give data on some atoms, particularly the heavy onea. some of which are fissionable. Natural radioactivity of certain heovy elements has long been known. Rate of disintegration la not affected by physi cal conditions or chemical action. Note in table above that radium it merely No. 7 In one radioactive series that started URANIUM iaoioaoim shim Element Uranium Ihbtlum Preoli"i* Uranium Thorium Sodium todan ltotop* tadration Hot! Hi* iU"* alpho ,,Th"* bats iPon* b*to ,,U"` alpha ThM* alpha ,,Ro"* alpha ..Ra1*' alpho 4J billion yr 34 (toy* 1.14 nlnvtai 335,000 yr 60.000 yr 1670 yr 3.1? day* ATOM SMASHING bHHMrcWut Slow proton -------- (lew-proton (or olphe-porlicle) "baflati'' ore pwihed oildo by nudeut (olwOyi poiftlvety charged. So high energy I* ireodud to hit Alpha particle * a helium audaui (3 protan* end 3 neutron* Alpha omlttloo reducer man numbor by 4 and otamic umbnr by 3. *ef portlda if on atactroa at negligible man, o nmldlan daatn'l (hang* man number bu* raltai atomic number by I, change* ntulron to proton. to- ntution __ Neutron bulleli, haring no charge, ora not rop*Hd. II tad, they more oflon etcope. il low and rtotoly olmed, they or# trapped by powerful "adhodra" (orcar MASS ANO ENERGY INTERCHANGE EiNSTEINi [ s MC* where f s energy In urg* hi s converted moi*. gram* C -- velocity ofllghl, cm/te 8 30X00,000,000 So one gram s 900 qulntlllion ergi one lb mot* s 11.4 billion Iwhr C 39 trillion 6iu s 30 quadrillion It tb 8 3.73 i 10" men unit* ATOMIC CONVERSION Shorthand formula below toy* helium "feudel" hitting nitrogen 14 knock* out hydrogen atom ond ieovet etygen 17i iHe` + iH""* ,Om + ,M* Preiont 37 61 Neutreni 3 7 90 Nudeont 4 14 17 I ..naturally, or artificially, with a corresponding energy conversion billions of years ago with uranium 238. Halt Hie of a radioactive substance is time required for half the original weight to disintegrate into another nearby element or isotope. Half lives vary apeetocularly from billions of years to a Uny fraction of a second. Thus it takes 44 billion years (table above) for half a given moss of U238 to change to thorium 234. Yet a given moss of Th234 takes only 24 days to change half Itself to protactinium 234. Artificial breakdown of atom structures is now carried out in "atom smashers." These hurl high-velocity particles at otomlc nuelei. The "bullets" are charged particles (protons, electrons, helium nuclei, etc.) propelled by electric Adds and steered by magnetic Acids. A neutron makes the best atomic bullet of all but cannot be directly accelerated in'an atom smasher because It has no chorge. But flying neutrons from exploded atoms are the sole means of propagating chain reactions in power reactors. As given by Einstein's famous formulo (above), a reduc tion in moss means a release of energy. Complete oblitera tion of one lb of matter would release 11.4 billion kwhr. FUSION QT URANIUM 235 FAST (BOMB) CHAIN REACTION CONTROLLED 1 CHAIN REACTION CONVERTING U2J6 TO PLUTONIUM ARITHMETIC OF BREEDING Whan U335 oKn "iplll*", ipore naulrem ore eiactad. There too, 1a turn, ipllt ether U335 otaaii. II chain rooctlon continual mil oo lb ii flulonad 1/<000 lb will ba converted to energy Ai shown In bolonca ihaal (right! tola! porilclai ollar fittloa aquol toTol belore. Actuol IIi*leo product! ond numbor ol naa. Iron* amittad very Irem ono Union to am! In U335 fotol balora Union after lo>gar Irogmant Smoilor Irogmont Olichorgod nautrom Total otter Union 93 144 334 Kata ol growth lor bomb with 0 reproduction loclor ol 7 Whan lovarot placet, aoch tat* than criti cal mot*, com* together quickly, choin reoclion occun ot tiplotW* ipaad until frag* manti laparota anough lo go baiow crltlcot "Splitting" heavy atoms yields vast energy and fission products Only fissionable substance found in nature is uranium 235, o rare form of natural uranium (one part U235 to 139 porta U238). When hit by o neutron, the U235 nucleus splits into two lighter atoms and ejects several (2.5 average) spare neutrons. These'new-bom neutrons can. in turn, split other IS23S atoms. This chain reaction moves to completion with explosive speed in a bomb or gradually in a power reactor. Whether fission be fast or slow, complete fission of any mass of U23S converts 1/1000 part of the mass into energy, according to the Einstein formula. Uranium bombs use concentrated U23S, extracted at great cost from natural uranium. Power reactors may use natural uranium, or natural uranium plus U23$ or plutonium. A lump ol U23S smaller than o certain unrevcalcd critical mats will not maintain a chain reaction. This Is because mall pieces have more surface per unit of volume, hence let more neutrons escape without splitting atoms. The Smyth report states, vaguely, that the critical moss of pure U23S (a material much heavier then lead) Is more than two lb and less than 200 lb. 90 report on atomic energy P9-4 predud^qoiMMMi P f U tioterot-uranlum reoctor, "ilew" neutre pill U335 olomt, Elected fait neulroni < fleered by moderator, iplli other U235 emi. Seme nevtroni ore led. Seme, traps by U336. dert o chain ceding with U33I capture* neutron to became V3J9. tn IwO *l*p*, ever iev*rel day*, thli decay* la plutonium 239, equal to U735 e* fuel. Nate lhal electron.election merely chongo* a neutre* to proton, doom'* chongo Ibo numbor (239) l perllcloi tn Iho nuclout 18 Weight el Pu (plutonium) produced by "burning" on* tb of U235 or tv. II fuel produced Ii, in torn, burned to moke more, end to on, thoerellcel total foot produced I* R+ 6* R* . ,. al-MI-61-l tiamploi With reproduction rale (I) Of 0.3, one lb ef U23J make* one lb of now feelr If R wore 0.6, new fuel mod* woM be 4 lb How fission occurs decides whether we have a bomb or a reactor An atom bomb contains much more than the critical mass divided into several pieces, eoch leas than critical. When these are brought together at high speed, a choin reaction occurs at explosive speed until fragments separate (or *noulH to bring remaining mass below critical level. Critical moss of natural uranium is infinite, so a naturalUranium reactor can't work without addition of something to boost effectiveness of highly diluted U235. Moderator* 4o this by slowing down neutrons through multiple colli* ktonx. Slow neutrons ore easily captured by nuclei, so make far more "hits." Low speed is enough to split loosely bound U23S atoms. Typical moderators ore graphite, heavy water. In any reactor containing U238 (usually many U238 atoms for each U235 atom) some flying neutrons will be captured by U238 atoms and will convert them by ateps (see above) to plutonium. This can be separated chemically and used as a fissionable nuclear fuel equal to U23S. Thus, indirectly, we can "bum" not only costly U235 but o sub stantial part of the plentiful U238, "Breeding." as outlined above, offers the possibility of burning the whole mass. MY 1953 RESORT ON ATOMIC ENERGY 91