Kuwonongeka kwa ufa wa graphite kumakhudza kwambiri momwe riyakitala imagwirira ntchito, makamaka riyakitala yoziziritsidwa ndi mpweya wotentha kwambiri. Njira yochepetsera ma neutron ndi kufalikira kwa ma neutron ndi ma atomu a zinthu zowongolera, ndipo mphamvu zomwe zimatengedwa zimasamutsidwira ku ma atomu a zinthu zowongolera. Ufa wa graphite ndi woyeneranso pazinthu zoyang'ana plasma za ma reactor a nyukiliya. Olemba otsatirawa ochokera ku Fu Ruite akuwonetsa kugwiritsa ntchito ufa wa graphite mu mayeso a nyukiliya:
Pamene kuwala kwa neutron kukuwonjezeka, ufa wa graphite umachepa kaye, ndipo ukafika pamtengo wochepa, kuchepa kwake kumachepa, kumabwerera ku kukula koyambirira, kenako kumakula mofulumira. Kuti mugwiritse ntchito bwino ma neutron omwe amatulutsidwa ndi kugawanika, ayenera kuchepetsedwa. Mphamvu ya kutentha ya ufa wa graphite imapezeka poyesa kuwala, ndipo mikhalidwe yoyesera kuwala iyenera kukhala yofanana ndi momwe zimagwirira ntchito pa reactor. Njira ina yowonjezerera kugwiritsa ntchito ma neutron ndikugwiritsa ntchito zinthu zowunikira kuti ziwonetse ma neutron omwe akutuluka mu nyukiliya fission reaction zone-core back. Njira yowunikira ma neutron ndi kufalikira kwa ma neutron ndi ma atomu a zinthu zowunikira. Pofuna kuwongolera kutayika komwe kumachitika chifukwa cha zonyansa kufika pamlingo wovomerezeka, ufa wa graphite womwe umagwiritsidwa ntchito mu reactor uyenera kukhala wa nyukiliya.
Ufa wa graphite wa nyukiliya ndi nthambi ya zipangizo za ufa wa graphite zomwe zinapangidwa poyankha zosowa za kupanga ma reactor a nyukiliya kumayambiriro kwa zaka za m'ma 1940. Umagwiritsidwa ntchito ngati wowongolera, wowunikira komanso womanga m'ma reactor opanga, ma reactor oziziritsidwa ndi gasi komanso ma reactor oziziritsidwa ndi gasi otentha kwambiri. Kuthekera kwa neutron kuchitapo kanthu ndi nucleus kumatchedwa gawo lopingasa, ndipo gawo lopingasa la thermal neutron (mphamvu yapakati ya 0.025eV) la U-235 ndi lapamwamba kwambiri kuposa gawo lopingasa la fission neutron (mphamvu yapakati ya 2eV). Modulus yosalala, mphamvu ndi kufalikira kwa mzere wa ufa wa graphite zimawonjezeka ndi kuwonjezeka kwa fluence ya neutron, zimafika pamtengo waukulu, kenako zimachepa mwachangu. Kumayambiriro kwa zaka za m'ma 1940, ufa wa graphite wokha ndi womwe unkapezeka pamtengo wotsika mtengo pafupi ndi chiyero ichi, ndichifukwa chake reactor iliyonse ndi ma reactor opanga omwe adatsatira adagwiritsa ntchito ufa wa graphite ngati chinthu chowongolera, zomwe zimayambitsa nthawi ya nyukiliya.
Chinsinsi chopangira ufa wa graphite wa isotropic ndikugwiritsa ntchito tinthu ta coke tomwe tili ndi isotropy yabwino: isotropic coke kapena macro-isotropic secondary coke yopangidwa kuchokera ku anisotropic coke, ndipo ukadaulo wa secondary coke umagwiritsidwa ntchito nthawi zambiri pakali pano. Kukula kwa kuwonongeka kwa radiation kumakhudzana ndi zopangira za ufa wa graphite, njira yopangira, kufulumira kwa neutron fluence ndi fluence rate, kutentha kwa radiation ndi zina. Boron yofanana ndi ufa wa graphite wa nyukiliya imafunika kukhala pafupifupi 10 ~ 6.
Nthawi yotumizira: Meyi-18-2022