Sample records for ydinjaetelaitoksen normaalikaeytoen kaeyttoehaeirioeiden

  1. Assessment of radiation doses due to normal operation, incidents and accidents of the final disposal facility; Kaeytetyn ydinpolttoaineen loppusijoituslaitoksen normaalikaeytoen, kaeyttoehaeirioeiden ja onnettomuustilanteiden aiheuttamien saeteilyannosten arviointi

    Rossi, J.; Raiko, H.; Suolanen, V.; Ilvonen, M. [VTT Energy, Espoo (Finland)


    Radiation doses for workers of the encapsulation and disposal facility and for inhabitants in the environment caused by the facility during its operation were considered. The study covers both the normal operation of the plant and some hypothetical incidents and accidents. Occupational radiation doses inside the plant during normal operation are based on the design basis, assuming that highest permitted dose levels are prevailing in control rooms during fuel transfer and encapsulation processes. Release through the ventilation stack is assumed to be filtered both in normal operation and in hypothetical incident and accident cases. Calculation of the offsite doses from normal operation is based on the hypothesis that one fuel pin per 100 fuel bundles for all batches of spent fuel transported to the encapsulation facility is leaking. The release magnitude in incidents and accidents is based on the event chains, which lead to loss of fuel pin tightness followed by a discharge of radionuclides into the handling chamber and to some degree through the ventilation stack into atmosphere. The weather data measured at the Olkiluoto meteorological mast was employed for calculating of offsite doses. Therefore doses could be calculated in a large amount of different dispersion conditions, the statistical frequencies of which have, been measured. Finally doses were combined into cumulative distributions, from which a dose value representing the 99.5 % confidence level, is presented. The dose values represent the exposure of a critical group, which is assumed to live at the distance of 200 meters from the encapsulation and disposal plant and thus it will receive the largest doses in most dispersion conditions. Exposure pathways considered were: cloudsnine, inhalation, groundshine and nutrition (milk of cow, meat of cow, green vegetables, grain and root vegetables). Nordic seasonal variation is included in ingestion dose models. The results obtained indicate that offsite doses from normal operation remain at insignificant level i.e. less than 10 {mu}Sv per year. In the case of hypothetical incident and accident releases the offsite doses don`t either exceed the limit values set by the safety authority. (orig.) 10 refs.