Lithium Target for International Fusion Materials Irradiation Facility
Experimental Validation of IFMIF Lithium Target Long-Term Performance
Tech Area / Field
3 Approved without Funding
FEI (IPPE), Russia, Kaluga reg., Obninsk
- All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow
- JAERI, Japan, Tokyo\nENEA, Italy, Frascati
Project summaryIntroduction and Overview
The objective of the project is to valid experimentally the feasibility of a stable hydrodynamic mode of lithium jet flow moving on the concave back wall of IFMIF target during a long period of time (up to 8000 hours). It is necessary to determine the impact of the target corrosion and erosion wear, and of impurity content and amount changes on hydrodynamic characteristics of the jet.
At the time, the international IFMIF (International Fusion Materials Irradiation Facility) project purposed at designing a facility for fusion facility neutron irradiation has entered the stage of experimental validation and engineering design EVEDA (Experimental Validation and Engineering Design Activity). Neutrons with energy of 15MeV will be generated as a result of deuterium ions (accelerated to energy of about 40MeV) with a lithium target, which is a flat jet of liquid lithium. To provide a stable neutron flux and transfer heat released in lithium, the jet should be hydrodynamically stable, i.e. it should maintain its uniformity and constant thickness with wave amplitude on free surface less than 1mm. To preclude lithium boiling in vacuum, there is pressure built in the jet under the action of centrifuge force. For this purpose, lithium flow is arranged along the concave cylindrical surface of the target back wall. Jet width in the IFMIF should be 260, and thickness – 25mm, with lithium velocity up to 20m/s.
By the moment, hydrodynamic investigations of a flat horizontal water jet (width – 70 mm, thickness – 10mm) have been performed in Japan. In Italy, investigations of a curvilinear vertical (like in the IFMIF) water jet (width – 200 mm, thickness – 20mm) are being carried out. At Osaka University (Japan), investigations of a flat horizontal lithium jet (width – 70 mm, thickness – 10mm) are in progress. In Russia, under ISTC Project No.2036, during 2003-2004, detailed hydrodynamic investigations of a curvilinear (like in the IFMIF) water jet (width – 80mm, thickness – 8mm) have been accomplished, besides, of a curvilinear water jet with 70mm width and 10mm thickness, in a target mock-up designed for further investigations on the lithium experimental facility. Under the same ISTC Project No.2036, an LTF-M lithium research facility was designed at the SSC RF – IPPE, target mock-up investigations (width – 70 mm, thickness – 10mm) have been started on the facility. By the end of Project No.2036, hydrodynamic experimental investigations of lithium jet under the conditions close to real IFMIF conditions in terms of lithium velocity and temperature, and impurity content in it, besides, in terms of structural material composition of the target and circulation loop, will have been performed. Besides, lithium purification techniques and lithium impurity content controlling techniques are mastered on the facility.
Specialists from the laboratory of high-temperature liquid-metal coolants and heat pipes technology with the experience of work with liquid-metal coolants of 30-40 years participate in the project. They have developed the technology of liquid metals application as coolants for various purpose nuclear power systems. There are doctors and candidates of science among them, besides, senior scientists, leading engineers and skilled workers, constituting a majority. Besides, specialists highly qualified in the area of material study from Bochvar Institute participate in the project.
Expected Results and Their Application
The expected results should confirm feasibility of the target assembly long-term operation (up to 8000 hours) accepted in IFMIF project, and feasibility of lithium circulation loop long-term operation under the conditions specific to the IFMIF. The criterion of the target and loop normal performance is stable hydrodynamics of lithium jet in the target providing the specified thickness of the jet and legitimate wave amplitude on its surface. Results of comparative tests of two different stainless austenitic steels manufactured in Russia and the USA will be obtained. These are the steels supposed to be used in IFMIF project. Besides, the experimental data will be obtained on beryllium and hydrogen impurities space distribution and on accumulation of corrosion products in LTF-M circulation loop.
All the results will be used in the engineering design of IFMIF target and circulation loop (EVEDA stage) to reduce the value of the facility installation, to improve its technical performance and operation characteristics and to increase the quality of future scientific investigations. It is assumed that ISTC project participants will have an opportunity to participate directly in the development of the equipment for the real IFMIF facility.
Meeting ISTC Goals and Objectives
- The project provides to scientists and specialists connected with weapons and to specialists from the participating organizations the possibility to make their activities peace-oriented, related to the fusion energy development;
- Cooperation with the participants of IFMIF international project will promote the integration of Russian scientists into the International Scientific Community;
- The project supports peaceful fundamental and applied investigations and technology development, namely in the area of environment protection, energy production and nuclear safety;
- The project facilitates the solution of national and international engineering problems of atomic energy with fast neutron reactors under the Generation-4 and INPRO programs.
Scope of Activities
There are four tasks to be performed under the project:
- Monitoring of lithium jet hydrodynamic characteristics during the target mock-up long-term tests on LTF-M facility.
- Control of the fraction of nitrogen, oxygen, iron, nickel, chrome, beryllium impurities and hydrogen in lithium and their distribution in lithium loop during the long-term tests.
- Comparative corrosion-erosion tests of materials in lithium.
- Results presentation, preparing publications, issuing the final project report.
Role of Foreign Collaborators/Partners
In the course of project realization, there will be a quarterly information exchange with the collaborator on work results and discussions of the results. The collaborator provides the information about IFMIF project members’ activities and planned working meetings.
The collaborator submits comments on the research/technical reports (quarter, annual) and other research/technical products presented by ISTC project members.
During the work under the ISTC project, project members, JAERI specialists will inter-travel to check and discuss work results.
The collaborator participates in the inspections of project activities performed by ISTC specialists and facilitates in arranging visits to international meetings, conferences and working meetings.
There will be joint workshops and working meetings under the project.
Technical Approach and Methodology
The objective of the project can be achieved with experimental investigations using LTF-M research facility and IFMIF target assembly mock-up designed under ISTC project No.2036 during the period from June 01, 2002 to May 31, 2005. The target assembly mock-up (target) includes all the principal elements, has a geometric form of the full-scale target of IFMIF facility, with the only difference in cross dimensions of lithium jet. The full-scale jet is of 260mm in width and 25mm in thickness, and the mock-up – 70 and 10mm, correspondingly. Lithium jet velocity in the mock-up is equal to the velocity in the full-scale target (up to 20m/s). Lithium temperature at the mock-up inlet and at the full-scale target inlet up is the same and equal to 250ºС. Nitrogen, oxygen, hydrogen and carbon concentration will be maintained within the limits established for the IFMIF. However, the possibility and necessity to maintain the fixed impurity standards should be validated in the tests. Structural material of LTF-M target mock-up and circulation loop is austenitic stainless steel identical to the steel of IFMIF loop and target (18% of chrome, 10% of nickel).
Long-term performance of the target mock-up will be evaluated according to jet time stability. For that purpose, visual examination of jet surface under consistent circulation conditions will be performed regularly (once a day), besides, there will be high-speed photography and video shooting (no less than once per week). Besides, it is supposed to measure jet thickness and wave height on the surface periodically (once a month) using an electric-contact probe.
In order to solve Task 2, experimental and analytical methods will be applied. Calculations will be made on tritium and beryllium-7 isotope distribution in lithium loop, based on the model of impurity mass-transfer processes developed for sodium loops. Experimental analysis of mass transfer in LTF-M lithium loop will be carried out by periodic sampling and sample analysis in terms of metallic impurities and nitrogen content in it, and using a sampler-distiller to evaluate oxygen and a plug indicator to evaluate the total impurities in lithium. Tritium and deuterium behavior will be studied on light hydrogen (protium). An electrochemical hydrogen sensor is intended to be used for this purpose.
Systematic observations of impurities in lithium will give the information about their accumulation as a function of lithium loop in-service time, intensity of impurity sources and discharge, and about their influence on lithium jet stability in the target mock-up.
In order to estimate corrosion and erosion of structural materials of the target and, especially, of the nozzle, steels of two types will be tested on the installation with a rotating disk. In this case a rotating cylinder replaces the rotating disk, since it can better simulate flow hydrodynamics in IFMIF target. The modernized installation with a rotating cylinder is supplemented by a small circulation loop equipped with the means of lithium purification and impurity control. 316SS, low-activated ferritic-martensitic, and Х18Н10Т steels will be tested. This will make it possible to apply the results obtained on the LTF-М manufactured from Х18Н10Т to IFMIF full-scale facility, which is supposed to be manufactured from 316SS. After the tests in the rotating cylinder installation, steel samples will be subjected to metallographic tests in the Institute of Inorganic Materials named after Academician A.A. Bochvar (Bochvar Institute). Specialists from the Institute shall directly participate in the tests on the LTF-M and on the rotating cylinder installation and render advisory services. Results of all the tests and investigations will be analyzed and presented in the final research/technical report on the project as a whole and allow predicting IFMIF target performance.