국내 경수로형 원자로 냉각재 중의 14C 거동 특성 평가

Evaluation of 14C Behavior Charateristic in Reactor Coolant from Korean PWR NPP’s

강덕원, 양양희, 박경록

Abstract

This study has been focused on determining the chemical composition of 14C - in terms of both organic andinorganic 14C contents - in reactor coolant from 3 different PWR's reactor type. The purpose was to evaluatethe characteristic of 14C that can serve as a basis for reliable estimation of the environmental release at domesticPWR sites. 14C is the most important nuclide in the inventory, since it contributes one of the main dosecontributors in future release scenarios. The reason for this is its high mobility in the environment, biologicalavailability and long half-life(5730yr). More recent studies - where a more detailed investigation of organic 14Cspecies believed to be formed in the coolant under reducing conditions have been made - show that the organiccompounds not only are limited to hydrocarbons and CO. Possible organic compounds formed includingformaldehyde, formic acid and acetic acid, etc. Under oxidizing conditions shows the oxidized carbon forms,possibly mainly carbon dioxide and bicarbonate forms. Measurements of organic and inorganic 14C in variouswater systems were also performed. The 14C inventory in the reactor water was found to be 3.1 GBq/kg in PWRof which less than 10% was in inorganic form. Generally, the 14C activity in the water was divided equallybetween the gas- and water- phase. Even though organic 14C compound shows that dominant species duringthe reactor operation, But during the releasing of 14C from the plant stack, chemical forms of 14C shows thedifferent composition due to the operation conditions such as temperature, pH, volume control tank ventingand shut down chemistry.

Key Words : 경수로, 방사성이산화탄소(14CO2), 방출화학형, 냉각재, 액상시료, 전처리, PWR, Radiocarbon dioxide, 14C chemical form, Reactor coolant, Process sample.

Reference

JNFCWT

Online Submission

Korean Radioactive
Waste Society (KRS)

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