REAKSIYaI YaDROII MUSALSAL

REAKSIYaI  YaDROII MUSALSAL, reaksiyai az tasiri neytronho taqsimshavii yadrohoro guyand, ki dar jarayoni on zimni har yak taqsimshavi beshtar az yak neytron khorij meshavad va amalyoti mazkurro payvasta nigoh medorad. Az tasiri neytronho taqsim shudani yadrohoro bori avval (1939) olimoni nemis 0. Gan va F. Shtrasman kashf kardand. Badtar F. Jolio-Kyuri, E. Fermi, U. Zinn, L. Silard (Ssilard) va G. N. Flyorov nishon dodaand, ki hangomi taqsimshavii yadro andaryak 2—3 neytron khorij meshavad va in amr baroi amali namudani Reaksiyai yadroii musalsal musoidat mekunad.

Reaksiyai yadroii musalsal  az barkhurdi yak neytron bo yak yadro ogoz meshavad. Neytronhoe, ki hangomi pora shudani yadroi avvala hosil meshavand (nasli yakum) dar navbati khud yadrohoi digarro pora karda nasli navi neytronhoro ba vujud meorand va gayra. Masalan, az har se neytroni soni 2-toyash 2 yadroro pora kunad, pas- az 80 nasl ‘reaksiyae, ki bo takoni yak neytron ogoz shudaast jamei yadrohoi yak kilogramm moddai taqsimshavandaro faro megirad. Vusati reaksiyai musalsalro asosan az rui koeffisienti afzoish K muayyan mekunand, ki on ba nisbati shumorai neytronhon yak nasl bar shumorai neytronhoi nasli digar barobar ast. Sistemai kritiki gufta sistemaero menomand, ki dar on K = 1 buda dar rafti reaksiya miqdori neytronhon hosila tagyir nameyobad. Agar /G > 1 boshad, on sistemaro ifroti (badikritiki) meguyand: Dar in mavrid reaksiya chunon bosurat jarayon megirad, ki okhir tarkishi yadroi ba amal meoyad. Odatan na hamai neytronhoi hosila ba nishon rasida yadrohoro pora mekunand, chande az onho talaf meyoband. Agar miqdori talaf az had ziyod boshad Reaksiyai yadroii musalsal ba amal nameoyad. Andozahoi khatti va massai moddai taqsimshavanda har qadar khurd boshand, ehtimoli talaf yoftani neytronho hamon qadar kalon ast. Sharoiti musoide, ki zimni on dar moddai taqsimshavanda Reaksiyai yadroii musalsal  ba amal omada metavonad, sharoiti kritiki nom dorad. In sharoit az rui andozahoi geometri, zichi va massai modda muayyan meshavad. Alhol Reaksiyai yadroii musalsal  tanho dar uran va baze elementhoi movaroi uran (transurani), masalan, plutonii — 239 ba amal barovarda shudaast. Uran — 235 va uran — 2,33 khud az khud va yo az tasiri neytronho (sustgard yo tezgard) pora meshavand. Ehtimoli porashavii yadrohoi uran — 238 az tasiri neytronhoi tezgard (energiyaashon az 1 MeV kam nabuda) beshtar ast. Hangomi bo neytronhoi sustgard tasir kardan uran — 238 onhoro rabuda, ba, plutoniy —239 tabdil meyobad, ki khosiyathoi yadroiash ba hosiyathoi uran — 235 nazdikand. Tajhizoti tekhnikiero, ki dar on Reaksiyai yadroii musalsali khudnigohdorandayu idorashavanda ba amal ovarda meshavad, reaktori yadroi menomand.

F. Normurodov, Ya. Shukurov.