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Hydrogen and Helium in Metals

#3672


Hydrogen Isotopes and Radiogenic Helium in Metals

Tech Area / Field

  • CHE-OTH/Other/Chemistry
  • NNE-FUE/Fuels/Non-Nuclear Energy
  • SAT-SUF/Surface Transportation/Space, Aircraft and Surface Transportation

Status
8 Project completed

Registration date
13.12.2006

Completion date
28.01.2010

Senior Project Manager
Bunyatov K S

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Supporting institutes

  • St Petersburg State University / Institute of Physics, Russia, St Petersburg

Collaborators

  • Forschungszentrum Karlsruhe Technik und Umwelt, Germany, Karlsruhe

Project summary

The following results were obtained as a result of the ISTC Project #2276 activities:
  • A method of accelerated aging of metals and SM (by way of the production of 3He and of related defects) operating in tritium-containing media.
  • A method of detritiation of the samples and quantitative measuring of 3He content accumulated in the samples.
  • New experimental data on the kinetics of generation, accumulation and release of 3He from mock-up material and stainless steel (SS) type SS 321 (C0,1%; Cr18%; Ni10%; Ti0,7).
  • Data on the effect of 3He on the structure of mock-up material and SS.
  • Data on the effects of 3He on the kinetics of hydrogen isotope diffusion, solution, trapping, permeation and accumulation in mock-up material and SS.
  • Data on the synergistic 3He / hydrogen effects upon mechanical properties of SS.
  • Mathematical models of hydrogen transport in metals in the presence of 3He and of helium induced defects.
  • Data on the parameters of hydrogen diffusion and accumulation in mock-up material and SS in the presence of 3He.

The unique results obtained in the course of implementation of the Project #2276 set new problems. Solving of these problems goes beyond the framework of the Project #2276 and needs additional activity.

The main problem is the establishing of a model of trapping hydrogen in specific traps accompanied by permanent increase of binding energy. The elucidating of this question is of principal importance for prediction of a degradation rate of materials operating in tritium-containing media. To solve this problem it is necessary to perform a set of studies with the samples containing more than 100-150 appm of 3He.

In the course of studying of joint action of H2 and 3He on mechanical properties of SS some regularities in behavior of mechanical properties in dependence of test parameters were observed (the test temperature was in the range 300-870 K, 3He concentration – in the range 0-130 appm). Verification and improvement of these dependencies can be made after additional mechanical tests of the samples containing more than ~200 appm 3He.

In the course of implementation of the Project #2276 it has been shown that morphology of 3He clusters depends on temperature, at which the sample was heated. Morphology of clusters is appreciably changed at T>1100 K. Because the main range of test temperatures planned in the framework of the Project #2276 was below 870 K, the changes in 3He bubble number, as well as in shape and distribution of He bubbles were not studied systematically. More detailed studying of these processes is expedient to conduct on the welded samples of SS. In the course of welding a temperature of the sample is non-uniform (relatively low (400-500 K) at the ends of the sample, and up to the melting T (~1700 K) in the center of the sample). This will allow obtaining the whole spectrum of changes in morphology of helium bubbles for one sample.

The main goals of the Project are:

  1. Establishing the mechanism of accumulation of hydrogen isotopes in SS containing high concentration (>100 appm) of 3He.
  2. Studying of a joint action of H2 and 3He on mechanical properties of SS containing 200 appm of 3He.
  3. Verification of the obtained dependencies of synergistic effects of H2 and 3He on mechanical properties of SS containing ~200 appm 3He.

There is the following basis for solving the proposed additional problems in a short time and with minimal funding:
  • in the course of implementation of the Project#2276 the full complex of the necessary equipment and the proved methods for implementation of the necessary set of research works was created;
  • the most time consuming and expensive part of job – tritiation and aging of the samples is fulfilled. At present time the required quantity of the SS samples necessary for studying thermal desorption, mechanical properties and weld ability is prepared, 3He concentration in these samples will soon reach 100 – 200 appm;
  • highly qualified team including the scientists of different specialties is built.

Expected Results and Their Application

Main results expected in the framework of implementation of the extension of the Project:

  • data on the effect 3He (at concentration >100 appm) on the structure of SS;
  • data on the effect of 3He (at concentration >100 appm) on kinetics of diffusion, sorption, trapping, permeation and accumulation of hydrogen isotopes in SS;
  • data on the synergistic 3He / hydrogen effects on mechanical properties of in SS;
  • refined models of hydrogen transport in metal in the presence of 3He and of 3He induced defects.

Meeting ISTC Goals and Objectives
  • It is a pioneering scientific research with prospects for its results to be applied in various fields of science and industries;
  • The Project redirects the RFNC-VNIIEF scientific and engineering personnel and experimental capabilities from military to civilian tasks;
  • The Project encourages long- term integration of weapon scientists and engineers from Russia into the international scientific community.

Scope of Activities:
1) Detritiation of the samples and determination of 3He content
Duration: 9 months.
2) Study of the effects of high concentration (>100 appm) of 3He on sorption, accumulation and diffusion of hydrogen in SS.
Duration: 10 months.
3) Study of the joint effects of 3He and hydrogen isotopes on mechanical properties of SS.
Duration: 8 months.
4) Generalization of the results
Duration: 9 months.

Role of Foreign Collaborators/Partners

Dr. Ahmed Hassanein - Argonne National Laboratory (USA). Collaboration assumes scientific visits, discussion of details and experimental results obtained under the Project, as well as discussion of methods how to improve experiments, preparation of joint reports and publications, participation in scientific workshops in Russia and abroad.

Dr. Rion A. Causey - Sandia National Laboratories (USA). Collaboration provides for discussion of the work program and experimental results, preparation of joint publications, participation in scientific workshops in Russia and abroad.

Dr.Manfred Glugla Tritium Laboratory Research Central Experimental Department, Forschungszentrum Karlsruhe GmbH (Germany) The content of collaboration will consist in discussions of the program and the results of the experiments, participation in joint workshops in Russian Federation.

Technical Approach and Methodology

Technical Approach and Methodology for extra activities are based on the developed under Project # 2276 equipment and techniques, and available tritiated SS samples needed for research.

RFNC-VNIIEF has available equipment and techniques to detritiate the samples by thermodesorption and isotopic exchange techniques, to make quantitative measurement of 3Не accumulated in test samples and residual tritium after detritiation, to study diffusion of molecular and atomic hydrogen in metal, and to analyze mechanical properties of structural materials in hydrogen isotopes environment.

V.A. Fock Institute of Physics SPbSU offers equipment and techniques for research on the mechanism of hydrogen diffusion, capture and release under permeability conditions, and to study hydrogen and 3Не thermodesorption from samples.

The impact of 3Не on physical and mechanical properties of metal will be further investigated with samples of austenite SS – analogue of SS 321.

The samples will be detritiated by vacuum thermodesorption technique and technique of tritium isotopic exchange for protium.

Accumulated in samples 3Не and residual tritium will be recorded with updated gas- analyzer ELTRA OH 900.

To study the impact of 3Не on mechanical properties of SS, cylindrical samples will be subjected to tensile tests in inert gas and hydrogen at up to 900 К temperature.

Effect of 3Не on hydrogen isotopes permeability, diffusion and solubility of metals’ will be investigated with membrane samples by the standard technique and by concentration pulses technique.

Influence of 3Не on hydrogen sorption kinetics will be studied on flat samples by thermodesorption technique.

Morphology and structure of samples saturated with 3Не will be studied by optical and electron microscopy.


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