Research Reactor Decommissioning Research Articles

Radiochemical Analysis of Filters Used During the Decommissioning of Research Reactors for Disposal

Radiochemical Analysis of Filters Used During the Decommissioning of Research Reactors for Disposal

The Assessment of the Radioactive Inventory for the Solid Wastes from VVR-S Nuclear Research Reactor Decommissioning

The Assessment of the Radioactive Inventory for the Solid Wastes from VVR-S Nuclear Research Reactor Decommissioning

Preliminary Waste Characterization Measurements in FiR 1 TRIGA Research Reactor Decommissioning Project

The objective of the study has been to verify the calculated residual activity in the decommissioning waste of the TRIGA Mark II–type research reactor FiR 1 in Finland. Knowledge of the radioactive inventory of irradiated materials is important in the planning of decommissioning activities and is essential for predicting the radiological impact to personnel and the environment. Measurements are performed for low active material samples from outer parts of the reactor. Methods include gamma spectrometric measurements, composition measurements with mass spectrometry, oxidation measurements of especially 14C in graphite, and full combustion measurements of lithium-enriched shielding materials. Results are compared to estimates calculated with a combined Monte Carlo model of the reactor and a point-depletion code modeling the irradiation history. Decommissioning waste consists mainly of ordinary concrete, aluminum, steel, and graphite parts. Only preliminary measurements of low active samples are reported so far, but the same methods will be used later for characterizing and classifying dismantling waste. Some discussion of characterization requirements and future sampling is also included.

A study of the decommissioning procedure of an activated structure through an evaluation of the decommissioning cost for a research reactor

As decommissioning of a research reactor and a nuclear installation requires a long period of time from the decommissioning preparation work to the site remediation, the management of the data generated during the entire period of decommissioning is one of the most important tasks. In particular, the data obtained from research reactor decontamination and decommissioning activities can be important resources securing the safety and economic feasibility for other research reactor decommissioning. The owner of the research reactor and nuclear power plant need to submit decommissioning plan to the regulatory body at the starting stage of the research reactor and nuclear installation decommissioning project. The cost plan for decommissioning and the method for assessing the amount of exposure to protect workers must be stated in the decommissioning plan.This paper introduces the DES (Decommissioning Engineering System) that can be able to manage the data generated in the process of decommissioning of the TRIGA research reactor, to calculate an amount of waste, to evaluate decommissioning cost after deriving unit work productivity factor, and to predict the decommissioning process in advance. To verify the usability of this system and data integrity through connections among the unit systems, it describes the process to calculate the decommissioning cost using the data generated in dismantling an activated bio-shielding concrete in the TRIGA research reactor.As a result of the experiment to calculate the decommissioning cost with the TRIGA research reactor structure, it was found that the calculations were done precisely without flaw as the purpose of the experiment. Therefore, the DES can not only be used for other research reactors decommissioning, but also it is expected to be applied to other research reactors in the future. As a decommissioning cost between an activated concrete and a non-activated concrete according to the method of the dismantling procedure was significantly different, a study regarding the dismantling procedure needs more research.

Radiological assessment in case of an incident at the hot cells clean-up

The clean-up and decontamination of the hot cells will be performed in the second phase of the WWR-S research reactor decommissioning. Identification of possible incidents or accidents is the key element in radiological assessment and prevention. As major incident it was considered a fire burst that occurred during the progress of the clean-up operations. The postulated incident has, as a consequence, thick smoke generation from the burned radioactive material and the dispersion of this material in the environment through the technological ventilation system and the evacuation chimney. From the performed analysis it can be seen that in the case of an incident to the reactor hot cells, an operator engaged in intervention operations could take an effective dose of 5.29 Sv per event, coming from both external and internal exposure. Such an incident, if it happens, would be classified of level 3 on the INES scale.

Final Status of the Decommissioning of Research Reactors in Korea

A decommissioning project for the Korean Research Reactors KRR-1 and KRR-2 was started in 1997 and had been carried out with the goal of completion by the end of 2008. All the facilities were dismantled and the building surfaces decontaminated. The radioactive waste was packed into 200 liter drums and 4m3 containers and temporarily stored on site until their final disposal at the national repository facility. Some of the releasable waste was freely released and utilized for non-nuclear industries. The assessment of the residual radioactivity was carried out according to the Multi Agency Radiation Site Survey and Investigation Manual (MARSSIM), and accordingly, the safety of the site release was verified. The site and buildings will be cleared for reuse for non-nuclear purposes after a review of the assessment. In this paper, the final status of the decommissioning of research reactors in Korea including dismantlement processes, waste management, and a final assessment for unrestricted use of the site and buildings as the final goal of the decommissioning project will be described.

Final Status of the Decommissioning of Research Reactors in Korea

Final Status of the Decommissioning of Research Reactors in Korea

Radioactive waste management at the Paul Scherrer Institute, the largest Swiss national research centre

This paper presents the current radioactive waste management practices at the Paul Scherrer Institute (PSI). The PSI contributes to waste related problems in two aspects, namely to the scientific basis of waste management and disposal, and to the practical treatment and storage of radioactive waste. In addition to the tasks of treating on-site generated waste, PSI manages the wastes from medicine, industry, and research throughout Switzerland on behalf of the government. Therefore the Dismantling and Waste Management Section is a part of the Logistics Department at PSI. Proved and accepted methods have to be developed for the safe conditioning and storage of radioactive waste. Various waste treatment facilities exist at PSI. The conditioning facility is dedicated to sorting, compaction by a 120 t press, solidification with special cement, and embedding in concrete. Specialized facilities were constructed for waste from the decommissioning of research reactors. Activated aluminum and its alloys were melted in crucibles and embedded in concrete in a concrete container. After dismantling the structural material of the reactors, it was embedded in concrete in the same manner. For the conditioning of activated reactor graphite, a dedicated method was developed. Graphite was crushed to replace sand in the grout, for embedding radioactive waste in concrete containers. For accelerator waste, a walk-in hot cell equipped with an electrically driven manipulator is available where the highly activated large components (targets, beam dump) can be cut into pieces and embedded in concrete in containers. To guarantee the fulfillment of the demands of the regulators, the Dismantling and Waste Management Section applies an accredited quality management system for the safe collection, conditioning, and storage of radioactive waste.

Elements of record management system for the RA research reactor decommissioning

According to latest recommendations, the record management system of a nuclear facility should operate as a part of the integrated management information system, and is implemented at the very beginning of the facility?s life cycle. The record management becomes particularly important at the end of the operation of a facility and then the operational record management system gradually transforms to a decommissioning one. However there is a significant number of nuclear facilities in the world which have reached the decommissioning stage with out having neither the initial decommissioning plan nor the established record management system. The objective of this paper is to introduce constituted elements of the record management system for the decommissioning of the RA research reactor in the VINCA Institute of Nuclear Sciences, and to discuss future planned actions related to this matter.

Decommissioning of nuclear and radiation-hazardous objects of the russian science center “Kurchatov Institute”

Data are presented on research reactors which form the experimental base used for research in radiation materials science, neutron physics, solid-state physics, and other directions in science and technology. The characteristic features of the decommissioning of research reactors are analyzed. The results of work on the decommissioning of reactors and spent-fuel and radioactive-waste repositories are presented. 3 figures, 2 tables, 12 references.