itor ing ▁at ▁N uc lear ▁Power ▁Pl ants ▁Reg ulations ▁per ▁the ▁Japanese ▁N uc lear ▁Saf ety ▁Commission ▁pres cribe ▁some ▁standards ▁that ▁a ▁monitoring ▁system ▁at ▁a ▁power ▁producing ▁nuclear ▁plant ▁must ▁ad here ▁to . ▁ ▁For ▁the ▁purposes ▁of ▁reg ulation , ▁monitoring ▁systems ▁are ▁divided ▁into ▁two ▁categories . ▁Category ▁ 1 : ▁Design ▁of ▁the ▁monitoring ▁system ▁has ▁to ▁fit ▁S - class ▁se ism ic ▁criteria ▁and ▁have ▁divers ity ▁and ▁independence ▁in ▁the ▁channels ▁that ▁const itute ▁the ▁system . ▁Category ▁ 2 : ▁These ▁detect ors ▁are ▁connected ▁to ▁the ▁plant ▁emer gency ▁power ▁system . ▁ ▁Additionally , ▁a ▁condition ▁for ▁both ▁categories ▁is ▁that ▁it ▁have ▁the ▁ability ▁to ▁monitor ▁continu ously ▁and ▁record ▁its ▁results . ▁ ▁During ▁normal ▁operation , ▁plants ▁have ▁to ▁monitor ▁gas ▁and ▁liquid ▁radio active ▁eff lu ent ▁releases . ▁ ▁The ▁only ▁type ▁that ▁requires ▁continuous ▁monitoring ▁is ▁radio active ▁noble ▁g ass es , ▁although ▁some ▁require ▁monitoring ▁only ▁for ▁every ▁dis charge . ▁ ▁Other ▁types ▁of ▁radiation ▁must ▁be ▁monitor ed ▁week ly ▁or ▁month ly ▁according ▁to ▁the ▁reg ulations . ▁ ▁Oper ating ▁power ▁plant ▁sites ▁stream ▁read ings ▁from ▁environmental ▁radiation ▁detect ors ▁located ▁around ▁or ▁on ▁peri ph ery ▁of ▁the ▁site , ▁detect ors ▁meas uring ▁radiation ▁levels ▁leaving ▁the ▁plant ▁stack ▁( g ase ous ▁eff lu ents ), ▁and ▁detect ors ▁monitoring ▁the ▁radiation ▁of ▁the ▁dis charg ed ▁waste ▁heat ▁water . ▁