¹⁴C content in candu spent ion exchange resins and its release under alkaline conditions

Abstract

The total 14C content and its speciation (inorganic/organic) were measured in spent ion exchange resins (SIERs) received from Cernavoda Nuclear Power Plant (NPP). Also, 14C release from SIERs was investigated by desorption tests carried out in alkaline solution relevant for cementitious environment disposal. The method used for total 14C measurement consists of combustion in oxygen-rich atmosphere, while for speciation measurements, both in SIERs and in desorption solutions, an analytical method based on acid stripping and wet oxidation was applied. Around 97% from the total 14C inventory measured on the Cernavoda SIERs (33.7 kBq/g) was found to be in inorganic form and only 7% as organic 14C. Under alkaline conditions, 14C could be released both as gaseous and as soluble species: from the total 14C present in the SIERs samples around 7% was released as inorganic 14C in the gas phase and 79% as dissolved species (mainly as inorganic 14C). These percentages were obtained for unconditioned SIERs in NaOH solution. The SIERs will be immobilized in a suitable matrix for disposal, and the presence of Ca ions dissolved in cement pore water favor precipitation of 14C and consequently the amount of 14C released from disposal area should be lower.

Feasibility study of synthesizing graphene quantum dots from the spent resin in a nuclear power plant to reduce disposal cost

“…In the case of pressurized water reactor (PWR), the waste is generated in Chemical and Volume Control System (CVCS), Spent Fuel Pool (SFP), Liquid Radioactive Waste System (LRS), Steam Generator Blowdown System (SGBDS), and Spent Fuel Pool and Cleanup System (SFPCCS) and in case of pressurized heavy water reactor (PHWR), it is generated in Moderator system (MOD) and Primary Heat Transport System (PHTS). 1,2 Liquid radioactive waste generated from various systems is purified through the ion-exchange resin in the demineralization system as shown in Figure 1. 3 The generated spent resin is stored in spent resin storage tanks as 20% of a mixture of zeolite and activated carbon, and 80% of the spent resin.…”