Two IAEA expert missions on characterization of irradiated graphite (hereinafter: iGraphite) and on waste form determination procedures are being held at ChNPP from 27 to 31 May 2019 as part of the national technical cooperation project.
Both topics are extremely important for ChNPP. The problem of characterization of iGraphite is closely connected with plant's decommissioning progress which stipulates management of iGraphite packages to be obtained as a result of fuel channels and control and protection system rods management scheduled to be started in 2021. The management process of iGraphite packages is identical to those of long-lived radioactive waste (RAW), stipulating that for further management, the packages should be characterized as for the nuclide content, which requires the relevant methodology to be developed and approved.
This expert mission is not the first one held in this direction. In June 2017, IAEA experts were reviewing the ChNPP technical solution on iGraphite management and found the results of the previously performed characterization of graphite rings of five fuel channels of ChNPP Reactor 2 acceptable as the basis for graphite characterization. However, for this purpose it is necessary to develop and describe the relevant methodology for characterization of packages.
As a result of this expert mission, available characterization procedures and technology which could be applied at ChNPP will be identified. It is also anticipated to prepare through joint efforts the road map on the development of ChNPP's iGraphite Characterization Methodology.
The second problem ChNPP specialists together with IAEA experts are working on is relevant to the final product produced at the Liquid Radioactive Waste Treatment Plant (hereinafter: LRTP). These are RAW packages representing 200-liter drums containing liquid waste solidified through cementation, which are transported for disposal to the Engineered Near-Surface Disposal Facility.
The methods used at LRTP for characterization of packages can provide measurement results as for radionuclide leaching rate and mechanical strength of cement matrix at least within 28 days. However, to ensure continuous operation of the plant, these characteristics should be known within 7 days. Therefore, it is necessary to introduce other tried-and-tested express characterization methods. Consequently, the available methods, their compatibility with LRTP technology and acceptance criteria for disposal became the subject of discussion during this expert mission.
In addition to IAEA experts, representing Great Britain and Lithuania, and the ChNPP specialists, the mission was attended by representatives of SSTC NRS, Chornobyl Centre, and ISP NPP.
