Towards the Standardization of Small Specimen Test Techniques for Fusion Applications - Phase II

Open for proposals

Project Type

Coordinated Research Project

Project Code

F13021

CRP

2348

Approved Date

9 February 2022

Status

3 - Active - Ongoing

Start Date

14 June 2022

Expected End Date

1 September 2026

Participating Countries

Argentina
Belgium
China
Germany
Hungary
Japan
Spain
United Kingdom of Great Britain and Northern Ireland
United States of America

Description

Fission neutrons for materials testing have been available for decades in hundreds of experimental reactors worldwide; an extensive database for irradiated materials is available. Unfortunately, experimental Fusion reactors for materials testing do not exist. Testing facilities with a 14 MeV neutron source for irradiating candidate materials under Fusion-reactor conditions and offering control of the temperature of the irradiated material have been subject of development for four decades, but now have become an urgent need and crucial feature in world Fusion roadmaps. The available volumes for testing will be inherently reduced; in the design of IFMIF (International Fusion Materials Irradiation Facility) or its simplified versions the Japanese A-FNS or the European IFMIF/DONES, a maximum of 500 cm3 will allow the irradiation of structural materials at the needed dpa values. The optimization of the limited testing space makes the use of small specimens a stringent necessity.
The limited testing volume with needed neutron fluxes in accelerator driven Fusion relevant neutron sources drove the development of small specimens for fusion applications. The first review of the state-of-the-art dates from 1983. The development has continued in a steady manner in various laboratories worldwide yielding similar results, but without a standard procedure. Since 1983, more than 10 specific Symposia have taken place, mainly organized by ASTM, but no harmonization of small specimens test techniques has yet ever been accomplished.
The nuclear industry, and in particular Fusion, has detected that the lack of common practice and standards in Small Specimen Test Techniques (SSTT) is preventing them to be able to compare and to use data in a rigorous manner. Standards reduce the risk of rejection of data gathered by validation and QA procedures of Nuclear Code Frameworks, prevents from likely repetition of tests and, therefore, accelerates material development and qualification cycles.
 
This CRP is a continuation of the effort started already in the previous CRP F1.30.17 on “Towards the Standardization of Small Specimen Test Techniques for Fusion Applications”. In this second phase of the project focus shall be on the applicability of guidelines and methodologies drafted so far under high temperature (HT) conditions and suited for hot cell (HC) environment as well as closing some gaps in the output of CRP F1.30.17
 
 

Objectives

The overall objective of this research proposal is to provide the bases for the standardization of SSTT specimens making them available for their use in Fusion material irradiation facilities. This includes:

(a) to provide a set of guidelines for SSTT based on common agreed best practices on main test techniques (tensile, creep, low cycle fatigue, fracture toughness, fatigue crack growth) valid for reference structural Fusion materials (RAFM steels);
(b) to establish supporting experimental activities and
(c) to elaborate datasets and elements needed for a full standardization of the SSTT by an international authority like ASTM or ISO.
This effort started already in the previous CRP F1.30.17 on “Towards the Standardization of Small Specimen Test Techniques for Fusion Applications” and this new CRP would be the second phase of it.

Both, the development of guidelines and the accompanying experimental programme shall be building on the CRP F1.30.17 and complementary focus on high temperature application and remote capabilities as required in hot-cell experiments.

It shall be noted, that the standardization through an international body itself is not an objective of this CRP

Specific objectives

Continuation of the supporting experimental program (“Intercomparison exercise from different labs”) for the respective test methods. The focus shall be on the applicability of guidelines and methodologies drafted so far under high temperature (HT) conditions and suited for hot cell (HC) environment as well as closing some gaps in the output of CRP F1.30.17 that are specific for the respective test methods addressed.

To establish reference guidelines for tensile tests using small specimens for RAFM steels. A focus will be given on achieving a firm basis of test results at elevated temperatures. Formulation of guidelines shall follow criteria and practice from well-established standards like ASTM or ISO.

To establish reference guidelines for creep tests using small specimens for RAFM steels. A focus will be given on consolidating the test results to analyse the consistency of the data to be obtained for the test matrix defined in CRP_SSTT-I. Formulation of guidelines shall follow criteria and practice from well-established standards like ASTM or ISO.

To establish reference guidelines for low cycle fatigue tests using small specimens for RAFM steels. A focus will be given on testing small specimens at diameters which will allow to recommend a minimum diameter. Formulation of guidelines shall follow criteria and practice from well-established standards like ASTM or ISO.

To establish reference guidelines for fracture toughness tests using small specimens for RAFM steels. A focus will be given addressing technical gaps/challenges. Formulation of guidelines shall follow criteria and practice from well-established standards like ASTM or ISO.

To establish reference guidelines for fatigue crack growth tests using small specimens for RAFM steels. A focus will be given on achieving a firm basis of test results at elevated temperatures. Formulation of guidelines shall follow criteria and practice from well-established standards like ASTM or ISO.

To establish guidelines for the use of SSTT taking into account the need of integrating these elements or data gathered from SSTT into nuclear code frameworks.

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