Cov kab lus qhia txog dab tsi nuclear fission yog, qhov txheej txheem no tau tshawb pom thiab piav qhia li cas. Nws siv los ua qhov chaw ntawm lub zog thiab riam phom nuclear tau tshwm sim.
"Indivisible" atom
Nyob rau xyoo pua nees nkaum yog cov lus qhia xws li "zog ntawm atom", "nuclear technology", "radioactive pov tseg". Txhua txhua tam sim no thiab tom qab ntawd hauv cov ntawv xov xwm xov xwm tshaj tawm xov xwm txog qhov muaj peev xwm ntawm cov kab mob sib kis ntawm cov av, dej hiav txwv, dej khov ntawm Antarctica. Txawm li cas los xij, ib tus neeg zoo tib yam feem ntau tsis muaj lub tswv yim zoo ntawm qhov kev tshawb fawb no yog dab tsi thiab nws yuav pab tau li cas hauv lub neej niaj hnub. Nws yog tsim nyog pib, tej zaum, nrog keeb kwm. Los ntawm thawj lo lus nug, uas tau nug los ntawm tus neeg noj zaub mov zoo thiab hnav khaub ncaws, nws xav paub seb lub ntiaj teb ua haujlwm li cas. Yuav ua li cas lub qhov muag pom, vim li cas pob ntseg hnov, dej txawv ntawm pob zeb - qhov no yog dab tsi txhawj xeeb cov neeg txawj ntse los ntawm lub sij hawm immemorial. Txawm tias nyob rau hauv ancient Is Nrias teb thiab tim Nkij teb chaws, ib co inquisitive minds qhia hais tias muaj ib tug tsawg particle (nws tseem hu ua "indivisible") uas muaj cov khoom ntawm ib tug khoom. Medieval chemists tau lees paub qhov kev kwv yees ntawm cov neeg txawj ntse, thiab cov ntsiab lus niaj hnub ntawm lub atom yog raws li hauv qab no: lub atom yog qhov me tshaj plaws ntawm cov khoom uas yog tus tuav ntawm nws cov khoom.
Parts ntawm ib atom
Txawm li cas los xij, kev txhim kho thev naus laus zis (hauvtshwj xeeb, kev yees duab) tau coj mus rau qhov tseeb tias lub atom tsis suav tias yog qhov tsawg tshaj plaws ntawm cov teeb meem. Thiab txawm hais tias ib qho atom yog hluav taws xob nruab nrab, cov kws tshawb fawb tau pom sai sai tias nws muaj ob feem nrog cov nqi sib txawv. Tus naj npawb ntawm qhov zoo them nqi them rau tus naj npawb ntawm qhov tsis zoo, yog li lub atom tseem nyob nruab nrab. Tab sis tsis muaj tus qauv tsis meej ntawm lub atom. Txij li thaum classical physics tseem muaj nyob rau lub sijhawm ntawd, ntau qhov kev xav tau ua.
Atom qauv
Thaum xub thawj, tus qauv "raisin yob" tau thov. Tus nqi zoo, raws li nws tau, tau sau tag nrho qhov chaw ntawm lub atom, thiab cov nqi tsis zoo tau muab faib rau hauv nws, zoo li raisins hauv ib lub pob. Qhov kev sim nto moo ntawm Rutherford tau txiav txim siab cov hauv qab no: lub caij hnyav heev nrog cov nqi zoo (lub nucleus) nyob hauv nruab nrab ntawm lub atom, thiab ntau cov hluav taws xob sib zog nyob ib puag ncig. Qhov loj ntawm lub nucleus yog ntau pua lub sij hawm hnyav dua qhov suav ntawm tag nrho cov electrons (nws yog 99.9 feem pua ntawm cov huab hwm coj ntawm tag nrho cov atom). Yog li, Bohr tus qauv planetary ntawm lub atom tau yug los. Txawm li cas los xij, qee qhov ntawm nws cov ntsiab lus tsis sib haum xeeb uas tau lees txais classical physics. Yog li ntawd, ib qho tshiab, quantum mechanics tau tsim. Nrog nws cov tsos, lub sijhawm tsis yog classical ntawm kev tshawb fawb pib.
Atom thiab radioactivity
Los ntawm tag nrho cov saum toj no, nws pom tseeb tias lub nucleus yog ib qho hnyav, zoo them ib feem ntawm lub atom, uas ua rau nws ntau. Thaum lub quantization ntawm lub zog thiab txoj hauj lwm ntawm electrons nyob rau hauv lub orbit ntawm ib tug atom tau zoo to taub, nws yog lub sij hawm los to taub.qhov xwm ntawm atomic nucleus. Lub ingenious thiab npaj txhij txog pom radioactivity tuaj cawm. Nws pab qhia cov ntsiab lus ntawm qhov hnyav nruab nrab ntawm lub atom, txij li lub hauv paus ntawm radioactivity yog nuclear fission. Thaum lub sij hawm tig ntawm lub kaum cuaj thiab nees nkaum centuries, discoveries rained ib tug tom qab lwm. Txoj kev daws teeb meem ntawm ib qho teeb meem xav tau kev sim tshiab. Cov txiaj ntsig ntawm kev sim ua rau muaj kev xav thiab kev xav uas yuav tsum tau lees paub lossis tsis lees paub. Feem ntau qhov kev tshawb pom loj tshaj plaws tau tshwm sim los ntawm qhov yooj yim vim hais tias yog li cas cov qauv tau yooj yim los suav (xws li, piv txwv li, Max Planck's quantum). Txawm hais tias thaum pib ntawm lub sijhawm ntawm kev yees duab, cov kws tshawb fawb paub tias uranium ntsev teeb rau cov duab thaij duab, tab sis lawv tsis xav tias nuclear fission yog lub hauv paus ntawm qhov tshwm sim no. Yog li ntawd, radioactivity tau kawm txhawm rau nkag siab qhov xwm txheej ntawm nuclear lwj. Pom tseeb, cov hluav taws xob tau tsim los ntawm kev hloov pauv quantum, tab sis nws tsis meej meej tias leej twg. Cov Curies mined ntshiab radium thiab polonium, ua haujlwm yuav luag ntawm tes hauv uranium ore, los teb cov lus nug no.
Tus nqi hluav taws xob hluav taws xob
Rutherford tau ua ntau yam los kawm txog cov qauv ntawm lub atom thiab pab rau kev kawm txog qhov fission ntawm atom nucleus tshwm sim li cas. Tus kws tshawb fawb tau tso cov hluav taws xob tso tawm los ntawm cov khoom siv hluav taws xob hauv cov hlau nplaum thiab tau txais txiaj ntsig zoo heev. Nws muab tawm tias cov hluav taws xob muaj peb yam: ib qho yog nruab nrab, thiab lwm yam ob yog qhov zoo thiab tsis zoo. Txoj kev kawm ntawm nuclear fission pib nrog lub ntsiab lus ntawm nwscov khoom. Nws tau ua pov thawj tias cov nucleus tuaj yeem faib tau, muab ib feem ntawm nws cov nqi zoo.
qauv ntawm lub nucleus
Tom qab nws tau pom tias lub atomic nucleus tsis yog tsuas yog cov khoom zoo ntawm cov protons xwb, tab sis kuj muaj qhov nruab nrab ntawm cov neutrons. Ua ke lawv hu ua nucleons (los ntawm lus Askiv "nucleus", lub nucleus). Txawm li cas los xij, cov kws tshawb fawb tau rov qab mus rau qhov teeb meem: qhov loj ntawm lub nucleus (uas yog, tus naj npawb ntawm nucleons) tsis ib txwm cuam tshuam rau nws cov nqi. Hauv hydrogen, lub nucleus muaj tus nqi ntawm +1, thiab qhov loj tuaj yeem yog peb, thiab ob, thiab ib qho. Helium tom ntej no nyob rau hauv lub sij hawm lub sij hawm muaj ib tug nuclear nqi ntawm +2, thaum nws cov nucleus muaj los ntawm 4 mus rau 6 nucleons. Cov ntsiab lus nyuaj tuaj yeem muaj ntau qhov sib txawv ntawm qhov sib txawv rau tib tus nqi. Xws li kev hloov pauv ntawm atoms hu ua isotopes. Tsis tas li ntawd, qee qhov isotopes tau hloov mus rau qhov ruaj khov, thaum lwm tus neeg sai sai, vim tias lawv tau tshwm sim los ntawm nuclear fission. Lub hauv paus ntsiab lus dab tsi cuam tshuam rau tus naj npawb ntawm nucleons ntawm kev ruaj ntseg ntawm nuclei? Vim li cas qhov sib ntxiv ntawm tsuas yog ib lub neutron rau ib qho hnyav thiab ruaj khov nucleus ua rau nws tawg, mus rau kev tso tawm ntawm cov xov tooj cua? Oddly txaus, lo lus teb rau lo lus nug tseem ceeb no tseem tsis tau pom. Empirically, nws muab tawm hais tias ruaj khov configurations ntawm atomic nuclei sib haum mus rau tej yam nqi ntawm protons thiab neutrons. Yog tias muaj 2, 4, 8, 50 neutrons thiab / lossis protons hauv cov nucleus, ces cov nucleus yuav ruaj khov. Cov lej no tseem hu ua khawv koob (thiab cov kws tshawb fawb laus, cov kws tshawb fawb nuclear, hu ua lawv). Yog li, qhov fission ntawm nuclei nyob ntawm lawv qhov loj, uas yog, ntawm cov nucleons suav nrog hauv lawv.
Ntxhais, plhaub, siv lead ua
Nws tsis tuaj yeem txiav txim siab qhov tseem ceeb uas yog lub luag haujlwm rau kev ruaj ntseg ntawm cov tub ntxhais tam sim no. Muaj ntau ntau txoj kev xav ntawm tus qauv ntawm cov qauv ntawm lub atom. Peb lub npe nrov tshaj plaws thiab tsim kho feem ntau sib cav sib ceg ntawm ntau yam teeb meem. Raws li thawj zaug, lub nucleus yog ib tug poob ntawm ib tug tshwj xeeb nuclear kua. Zoo li dej, nws yog yam ntxwv ntawm fluidity, nto nro, coalescence thiab lwj. Hauv lub plhaub qauv, kuj tseem muaj qee lub zog hauv cov nucleus, uas muaj cov nucleons. Qhov thib peb hais tias lub hauv paus tseem ceeb yog qhov nruab nrab uas muaj peev xwm cuam tshuam cov nthwv dej tshwj xeeb (de Broglie), thaum lub zog refractive yog lub zog muaj peev xwm. Txawm li cas los xij, tsis muaj tus qauv tseem tuaj yeem piav qhia meej vim li cas, ntawm qee qhov tseem ceeb ntawm cov tshuaj no tshwj xeeb, nuclear fission pib.
kev sib ncaim zoo li cas
Radioactivity, raws li tau hais los saum toj no, pom muaj nyob rau hauv cov khoom uas tuaj yeem pom nyob rau hauv qhov: uranium, polonium, radium. Piv txwv li, freshly mined, ntshiab uranium yog radioactive. Txoj kev splitting nyob rau hauv cov ntaub ntawv no yuav spontaneous. Tsis muaj kev cuam tshuam sab nraud, qee tus lej ntawm uranium atoms yuav tawm alpha hais, hloov pauv mus rau hauv thorium. Muaj ib qho kev qhia hu ua ib nrab-lub neej. Nws qhia tau hais tias lub sijhawm twg los ntawm thawj tus lej ntawm qhov ib nrab yuav nyob twj ywm. Rau txhua qhov hluav taws xob hluav taws xob, ib nrab ntawm lub neej sib txawv - los ntawm feem ntawm ib thib ob rau Californiantau pua txhiab xyoo rau uranium thiab cesium. Tab sis kuj tseem muaj kev quab yuam hluav taws xob. Yog hais tias lub nuclei ntawm atoms raug foob nrog protons lossis alpha hais (helium nuclei) nrog lub zog kinetic siab, lawv tuaj yeem "sib cais". Cov txheej txheem ntawm kev hloov pauv, tau kawg, txawv ntawm qhov uas niam nyiam lub vase tawg. Txawm li cas los xij, muaj qee qhov piv txwv.
Atom Zog
Txog tam sim no, peb tsis tau teb cov lus nug uas siv tau: lub zog los ntawm qhov twg thaum lub sijhawm muaj kev sib tsoo nuclear. Yuav pib nrog, nws yuav tsum tau qhia meej tias thaum lub sij hawm tsim ntawm lub nucleus, tshwj xeeb nuclear rog ua, uas yog hu ua kev sib cuam tshuam. Txij li thaum lub nucleus yog tsim los ntawm ntau yam zoo protons, cov lus nug tseem yuav ua li cas lawv lo ua ke, vim hais tias cov electrostatic rog yuav tsum thawb lawv tawm ntawm ib leeg heev. Cov lus teb yog ob qho yooj yim thiab tsis nyob rau tib lub sijhawm: lub nucleus tau tuav ua ke los ntawm kev sib pauv ceev heev ntawm nucleons ntawm cov khoom tshwj xeeb - pi-mesons. Qhov kev sib txuas no nyob luv luv. Sai li qhov kev sib pauv ntawm pi-mesons nres, lub nucleus lwj. Nws kuj tseem paub tseeb tias qhov loj ntawm ib lub nucleus tsawg dua qhov sib npaug ntawm tag nrho nws cov nucleons. Qhov tshwm sim no hu ua qhov tsis xws luag. Qhov tseeb, qhov ploj lawm yog lub zog uas siv los tswj kev ncaj ncees ntawm cov nucleus. Thaum qee qhov sib cais los ntawm lub nucleus ntawm ib lub atom, lub zog no raug tso tawm thiab hloov mus rau hauv cov cua sov hauv nuclear fais fab nroj tsuag. Ntawd yog, lub zog ntawm nuclear fission yog ib qho kev qhia meej ntawm tus qauv Einstein nto moo. Nco qab tias cov qauv hais tias: lub zog thiab huab hwm coj tuaj yeem tig mus rau ib leeg (E=mc2).
Theory and practice
Tam sim no peb yuav qhia koj li cas qhov kev tshawb pom tseeb no tau siv hauv lub neej los tsim hluav taws xob gigawatts. Ua ntej, nws yuav tsum tau muab sau tseg tias kev tswj cov tshuaj tiv thaiv siv quab yuam nuclear fission. Feem ntau nws yog uranium los yog polonium, uas yog bombarded los ntawm ceev neutrons. Qhov thib ob, nws yog tsis yooj yim sua kom tsis txhob to taub hais tias nuclear fission yog nrog los ntawm cov creation ntawm tshiab neutrons. Yog li ntawd, tus naj npawb ntawm neutrons nyob rau hauv cov tshuaj tiv thaiv cheeb tsam tuaj yeem nce sai heev. Txhua lub neutron sib tsoo nrog cov tshiab, tseem tsis zoo nuclei, cais lawv, uas ua rau muaj kev nce hauv kev tso cua sov. Qhov no yog cov tshuaj tiv thaiv kab mob nuclear fission. Kev tswj tsis tau nce ntawm cov neutrons hauv lub reactor tuaj yeem ua rau tawg. Qhov no yog qhov tshwm sim hauv xyoo 1986 ntawm Chernobyl nuclear fais fab nroj tsuag. Yog li ntawd, nyob rau hauv cheeb tsam cov tshuaj tiv thaiv yeej ib txwm muaj ib yam khoom uas absorbs tshaj neutrons, tiv thaiv kev puas tsuaj. Nws yog graphite nyob rau hauv daim ntawv ntawm rods ntev. Tus nqi ntawm nuclear fission tuaj yeem ua rau qeeb los ntawm immersing cov pas nrig hauv thaj tsam tshuaj tiv thaiv. Qhov sib npaug ntawm cov tshuaj tiv thaiv nuclear tau muab tso ua ke tshwj xeeb rau txhua yam khoom siv hluav taws xob hluav taws xob thiab cov khoom tawg ua rau nws (electrons, protons, alpha hais). Txawm li cas los xij, qhov kawg ntawm cov zis hluav taws xob suav nrog raws li txoj cai kev txuag: E1 + E2=E3 + E4. Ntawd yog, tag nrho lub zog ntawm thawj nucleus thiab particle (E1 + E2) yuav tsum sib npaug ntawm lub zog ntawm cov nucleus uas tshwm sim thiab lub zog tawm hauv daim ntawv dawb (E3 + E4). Qhov sib npaug ntawm cov tshuaj tiv thaiv nuclear kuj qhia tau tias yam khoom twg tau txais los ntawm kev lwj. Piv txwv li, rau uranium U=Th+He, U=Pb+Ne, U=Hg+Mg. Cov isotopes ntawm cov ntsiab lus tsis tau teev nyob ntawm no.txawm li cas los xij, qhov no tseem ceeb. Piv txwv li, muaj ntau li peb muaj peev xwm rau kev sib cais ntawm uranium, uas sib txawv isotopes ntawm txhuas thiab neon raug tsim. Nyob rau hauv yuav luag ib puas feem pua ntawm cov neeg mob, cov tshuaj tiv thaiv nuclear fission tsim cov isotopes radioactive. Ntawd yog, kev lwj ntawm uranium tsim cov xov tooj cua thorium. Thorium tuaj yeem lwj mus rau protactinium, uas mus rau actinium, thiab lwm yam. Ob qho tib si bismuth thiab titanium tuaj yeem ua hluav taws xob hauv cov koob no. Txawm tias hydrogen, uas muaj ob protons nyob rau hauv lub nucleus (ntawm tus nqi ntawm ib tug proton), hu ua txawv - deuterium. Cov dej uas tsim los ntawm cov hydrogen no yog hu ua dej hnyav thiab ua rau lub hauv paus tseem ceeb hauv cov reactors nuclear.
Tsis sib haum xeeb atom
Cov lus hais xws li "kev sib tw caj npab", "kev ua tsov rog txias", "kev hem thawj nuclear" yuav zoo li keeb kwm thiab tsis cuam tshuam rau tus neeg niaj hnub no. Tab sis ib zaug dhau los, txhua qhov xov xwm tshaj tawm yuav luag thoob plaws ntiaj teb tau nrog cov lus ceeb toom txog pes tsawg hom riam phom nuclear tau tsim thiab yuav ua li cas nrog lawv. Cov neeg tsim cov bunkers hauv av thiab khaws cia thaum lub caij ntuj no nuclear. Tag nrho tsev neeg tau ua hauj lwm los tsim lub vaj tse. Txawm tias kev thaj yeeb nyab xeeb ntawm kev siv nuclear fission tshwm sim tuaj yeem ua rau muaj kev puas tsuaj. Nws yuav zoo li tias Chernobyl qhia tib neeg kom ceev faj hauv cheeb tsam no, tab sis cov ntsiab lus ntawm lub ntiaj teb tau ua kom muaj zog: av qeeg hauv Nyij Pooj tau ua rau lub zog ruaj khov ntawm Fukushima nuclear fais fab nroj tsuag. Lub zog ntawm cov tshuaj tiv thaiv nuclear yog yooj yim dua los siv rau kev puas tsuaj. Technologists tsuas yog yuav tsum tau txwv tsis pub lub zog ntawm qhov tawg, thiaj li tsis txhob cuam tshuam lub ntiaj teb tag nrho. Feem ntau "tib neeg" foob pob, yog tias koj tuaj yeem hu rau lawv, tsis txhob ua paug rau ib puag ncig nrog hluav taws xob. Feem ntau, lawv feem ntau sivuncontrolled chain reaction. Dab tsi lawv siv zog kom tsis txhob ntawm nuclear fais fab nroj tsuag los ntawm txhua txoj kev yog ua tiav hauv cov foob pob hauv txoj kev qub heev. Rau txhua yam khoom siv hluav taws xob, muaj qee qhov tseem ceeb ntawm cov khoom ntshiab uas muaj cov tshuaj tiv thaiv kab mob los ntawm nws tus kheej. Rau uranium, piv txwv li, nws tsuas yog tsib caug kilograms. Txij li thaum uranium hnyav heev, nws tsuas yog me me hlau pob 12-15 centimeters nyob rau hauv txoj kab uas hla. Thawj lub foob pob atomic poob rau Hiroshima thiab Nagasaki tau ua raws nraim raws li lub hauv paus ntsiab lus no: ob qhov tsis sib xws ntawm cov uranium ntshiab tsuas yog ua ke thiab ua rau muaj kev tawg txaus ntshai. Niaj hnub nimno riam phom tej zaum yuav sophisticated. Txawm li cas los xij, ib qho yuav tsum tsis txhob hnov qab txog qhov tseem ceeb: yuav tsum muaj kev txwv ntawm cov ntim me me ntawm cov khoom siv hluav taws xob ntshiab thaum lub sijhawm khaws cia, tiv thaiv cov khoom los ntawm kev sib txuas.
Radiation sources
Txhua lub ntsiab lus nrog tus nqi hluav taws xob ntau dua 82 yog cov xov tooj cua. Yuav luag tag nrho cov tshuaj sib zog muaj cov isotopes radioactive. Qhov hnyav dua lub nucleus, lub neej luv dua. Qee lub ntsiab lus (xws li California) tsuas yog tuaj yeem tau txais cov khoom siv dag zog - los ntawm kev sib tsoo hnyav atoms nrog cov khoom sib dua, feem ntau hauv cov accelerators. Txij li thaum lawv tsis ruaj khov heev, lawv tsis muaj nyob hauv lub ntiaj teb crust: thaum lub sij hawm tsim ntawm lub ntiaj teb, lawv sai heev disintegrated rau lwm yam. Cov khoom uas muaj cov nuclei sib dua, xws li uranium, tuaj yeem raug khawb. Cov txheej txheem no ntev, uranium tsim nyog rau kev rho tawm, txawm tias nyob hauv cov nplua nuj heev, muaj tsawg dua ib feem pua. peb txoj kev,Tej zaum qhia tau hais tias lub sijhawm tshiab geological tau pib lawm. Qhov no yog kev rho tawm cov khoom siv hluav taws xob los ntawm cov khoom siv hluav taws xob. Tom qab cov roj siv los ntawm cov chaw tsim hluav taws xob, ntawm lub nkoj nkoj lossis lub dav hlau thauj khoom, kev sib xyaw ntawm cov uranium qub thiab cov khoom kawg, qhov tshwm sim ntawm fission, tau txais. Tam sim no, qhov no suav hais tias yog cov khoom siv hluav taws xob pov tseg thiab muaj cov lus nug hnyav txog yuav ua li cas pov tseg lawv kom lawv tsis txhob ua phem rau ib puag ncig. Txawm li cas los xij, nws zoo li yav tom ntej, cov khoom siv hluav taws xob npaj tau npaj txhij (piv txwv li, polonium) yuav raug tshem tawm los ntawm cov khib nyiab no.
