Preliminary Occupational Radiation Exposure evaluation related to NET/ITER tritium systems (original) (raw)
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Preliminary occupational radiation exposure evaluation related to NET II/ITER
15th IEEE/NPSS Symposium. Fusion Engineering
This paper presents the criteria adopted to evaluate Occupational Radiation Exposure (ORE) during normal operation and maintenance of NET/ITER and some results concerning the fuel cycle systems located in the tokamak and tritium buildings. Prompt radiation, activity concentration, and intake situations as well as number of workers, number of events, and exposure time are considered. Many systems and components, whose location in the plant can affect radiological protection during maintenance and/or surveillance, are identified together with the operations needed for each activity. Accidental conditions and equipment failures have been considered in the special maintenance activity when they are due to events with a high probability of occurrence so that such events might be expected during the life of the plant. Some results are reported showing the ORE figures with reference to the main activities. The total man-Sv/y for the systems and activities considered is about 0.5. Such a result, even if very preliminary and incomplete, means that ORE for the tritium systems of a machine like NET/ITER is not negligible and has to be continuously controlled during the design phase.
Radiological safety during maintenance of the primary heat transfer system of the ITER plant
Proceedings of 16th International Symposium on Fusion Engineering, 1995
The primary heat transfer system (PHTS) of the ITER plant is devoted to the heat removal from different plasma facing components: the first wall, the blanket, the divertor and the vacuum vessel . The system requires a scheduled or regular maintenance that involve component checlung and changing, and a special maintenance that has a non periodic nature. During the maintenance operations some shelding barrier has to be partly or completely removed and workers are likely to be exposed to an unusual radiological dose.
Personnel Radiation Protection at the ITER Nuclear Fusion Facility
The hosting site for the ITER nuclear fusion experiment was finally chosen in France (Cadarache). The radiation protection program for the ITER personnel involved into operation and maintenance activities will be then tested in the near future. Related studies were mainly carried out during the last ten years and important assessments were performed at the Frascati ENEA Research Center in Italy. In this ambit individual and collective doses to the operators were calculated for different categories of working activities involving more and less critical systems. The radiation protection organization was outlined and the related program was proposed. A short review of the analyses performed in this field by the Italian investigators of the ENEA Radiation Protection Institute is shown here. The principal parameter taken into account in these evaluations was the collective dose due to the different working activities. This quantity has been assessed considering the following radiological...
Fusion Science and Technology, 2009
This paper details an Occupational Radiation Exposure (ORE) analysis performed for the US International Thermonuclear Experimental Reactor (ITER) Dual Coolant Lead Lithium (DCLL) Test Blanket Module (TBM). This ORE analysis was performed with the QADMOD dose code for maintenance activities anticipated for the US DCLL TBM concept and its ancillary systems. Identification of the maintenance tasks that will have to be performed and estimates of the time required to perform these tasks were developed based on either expert opinion or on industrial maintenance experience for similar technologies. This paper details the modeling activity and the calculated doses for the maintenance activities envisioned for the US DCLL TBM.
Fusion Engineering and Design, 2000
The international thermonuclear experimental reactor water cooling system (ITER WCS) is divided into 20 loops with the aim to reduce the consequences of a loss of coolant accident (LOCA). This makes the ITER WCS a very complicated system with many components requiring periodical inspection and maintenance. The main radiological concern for the staff involved in such activities is due to the activated corrosion products (ACPs) generated by corrosion of the inner wall of the piping under the neutron flux. In the present study the collective dose due to the ACP for one loop of the ITER WCS is assessed. Two different maintenance and inspection (M/I) approaches (or working strategies) for the ITER WCS components are to be considered. The first one is usually applied in American and European designs of pressurised water reactors (PWRs) that have cooling loops similar to those envisaged in ITER. The other one is the strategy proposed by the ITER WCS designers that takes into account the actual plant layout and technology. Both strategies have been implemented in the occupational radiation exposure (ORE) assessment process and two results have been obtained. The similarity is then performed pointing out the differences between the two approaches, trying to indicate what is the best one from the ORE point of view. : S 0 9 2 0 -3 7 9 6 ( 0 0 ) 0 0 2 5 1 -9
Radiological Safety Analysis for the Main Incidents of the ITER Systems
21st IEEE/NPS Symposium on Fusion Engineering SOFE 05, 2005
Two incidents among those defined for the ITER systems are analysed from the radiological safety point of view due to their major impact on the worker safety: • "In-vessel FW pipe break" • "Heat exchanger leakage". For both incidents no direct personnel exposure is envisaged during the events. Nevertheless, the maintenance activities needed to restore the systems to their original performance are responsible of an increase of the individual dose and of the Occupational Radiation Exposure (ORE). Maintenance scenarios are described for both the after-incidents situations and the related timing and person power are estimated and discussed. Dose rates related to the FW module operations are derived from previous analyses. Original new assessment of the dose rate in the operator position are performed in the current study to evaluate the impact of heat exchanger (HX) tube plugging. The radiological source term for the scenario is the activated corrosion product (ACP) already assessed for previous analysis. The evaluation of the inner surface concentration of ACP is based on the model prepared for the code PACTITER used to assess the source term. Computer models for dose rate assessment are presented. Collective doses for the repair activities following the two incidents are quantified for the maintenance activities to recover both the "in-vessel FW pipe break" and the "heat exchanger leakage".
Occupational Radiation Exposure Analysis of US ITER DCLL TBM
2007
This report documents an Occupational Radiation Exposure (ORE) analysis that was performed for the US International Thermonuclear Experimental Reactor (ITER) Dual Coolant Lead Lithium (DCLL) Test Blanket Module (TBM). This analysis was performed with the QADMOD dose code for anticipated maintenance activities for this TBM concept and its ancillary systems. The QADMOD code was used to model the PbLi cooling loop of this TBM concept by specifying gamma ray source terms that simulated radioactive material within the piping, valves, heat exchanger, permeator, pump, drain tank, and cold trap of this cooling system. Estimates of the maintenance tasks that will have to be performed and the time required to perform these tasks where developed based on either expert opinion or on industrial maintenance experience for similar technologies. This report details the modeling activity and the calculated doses for the maintenance activities envisioned for the US DCLL TBM.
Fusion Engineering and Design, 2007
The occupational radiation exposure (ORE) assessment for ITER systems is evolving as design makes progress. This paper deals with the ORE assessments for two important ITER activities: those in the assistance to the remote handling on a port plug hosting diagnostics and those carried out in the Waste Treatment System. For the former a software tool has been developed to handle the large amount of data processed and to allow user friendly updating of data as design or maintenance procedures evolves, and, know-how on maintenance activities improves. A systematic approach was adopted to evaluate work efforts (WE) needed to execute specific tasks. The so-called "elementary works" were identified and classified and the time required to perform the operation and involved people were estimated. The elementary works were then aggregated in the so-called main operations (e.g. window replacement, pipe removal, etc.). For each of them, on the base of expected maintenance frequency and dose rate fields, total WE and worker doses were calculated. It was assessed that hands-on activities in the Equatorial Port No. 1 require 472 person h of WE leading to a collective dose of ∼7.4 person mSv/year. The most critical operation in terms of worker doses is the sealing/unsealing of port plug, which weights for about the 23% of the total. The second ORE assessment was related to the management of ITER operational radioactive wastes. These wastes include streams originated in the plant from the experimental and maintenance activities, with exclusion of those generated inside the Tokamak that will be highly activated and will be managed inside the Hot Cell Processing System. The estimated collective annual dose related to the Waste Treatment System ranges between ∼4.3 and ∼4.9 person mSv. The two values depend on the assumptions made for the exposure levels in the operative areas. Both studies have to be considered as preliminary as far as the results are concerned due to the quite rough input data (on dose rates and design details), while the approach might be considered sound and up to date.
1984
The mission of the Manpower Education, Research, and Training Division, formed in 1977, is to enhance the knowledge and abilities of the professional and skilled work force involved in national energy, environmental, and health-related activities. The division is organized into five program areas that examine human resource issues, evaluate manpower requirements and training needs, assist in establishing manpower training programs, and provide opportunities for professional education and industrial craft training. The division's programs include the Assessment and Field Support Program, the Labor and Policy Studies Program, Professional Training Programs, the Training and Technology Program, and University Programs. NOTICES The opinions expressed herein do not necessarily reflect the opinions of the sponsoring institutions of Oak Ridge Associated Universities. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, nor assumes any legal liability or responsibility for any third party's use or the results of such use of any information, apparatus, product or process disclosed in this report, nor represents that its use by such third party would not infringe privately owned rights.
Recent Upgrades at the Safety and Tritium Applied Research Facility
Fusion Science and Technology, 2017
This paper gives a brief overview of the Safety and Tritium Applied Research (STAR) facility operated by the Fusion Safety Program (FSP) at the Idaho National Laboratory (INL). FSP researchers use the STAR facility to carry out experiments in tritium permeation and retention in various fusion materials, including wall armor tile materials. FSP researchers also perform other experimentation as well to support safety assessment in fusion development. This lab, in its present two-building configuration, has been in operation for over ten years. The main experiments at STAR are briefly described. This paper discusses recent work to enhance personnel safety at the facility. The STAR facility is a Department of Energy less than hazard category 3 facility; the personnel safety approach calls for ventilation and tritium monitoring for radiation protection. The tritium areas of STAR have about 4 to 12 air changes per hour, with air flow being once through and then routed to the facility vent stack. Additional radiation monitoring has been installed to read the laboratory room air where experiments with tritium are conducted. These ion chambers and bubblers are used to verify that no significant tritium concentrations are present in the experiment rooms. Standby electrical power has been added to the facility exhaust blower so that proper ventilation will now operate during commercial power outages as well as the real-time tritium air monitors.