1.0 Background
At present, irradiated pressure tube material properties are determined using industry test procedures that have not been standardized by standards organizations such as the American Society for Testing and Materials (ASTM) or the Canadian Standards Association (CSA). Results generated from the present test procedures are being used in the development of CSA Standard N285.8. The results are also being used to validate newly developed structural integrity methodologies intended by industry to support licensing submissions.
CSA Standard N285.4 requires pressure tube surveillance material tests; however, the results are not being generated through the application of publically reviewed standards. CNSC staff has assessed the need to standardize test procedures for irradiated pressure tubes, including pressure tube conditioning and pre-conditioning. Expertise is also being sought to facilitate the development of standardized test procedures under CSA or ASTM.
2.0 Objectives
The objective of this project is to facilitate the standardization of testing procedures for irradiated Zr-2.5Nb pressure tube material by proposing modifications to the applicable CSA or ASTM standards, or independent development of new standards or standard appendixes under CSA or ASTM.
3.0 Scope of Work
The scope of work includes:
3.1 Reviewing the ASTM Standard Test Method for Measurement of Fracture Toughness, document E-1820, and assessing its applicability to small curved compact tension specimen testing of irradiated Zr-2.5Nb pressure tube material utilized by the Canadian nuclear industry. The assessment is to provide a path forward to account for the latest theoretical understanding and advances in testing equipment.
3.2 Facilitating the standardization of testing procedures for Zr-2.5Nb pressure tube material by proposing modifications to applicable CSA or ASTM standards, or developing new draft standards or draft standard appendixes under CSA or ASTM.
The new draft standards or draft standard appendixes are to address:
a) as-received irradiated Zr-2.5Nb pressure tube materials; and
b) irradiated Zr-2.5Nb pressure tube materials subjected to elevated hydrogen concentrations. Both subjects of interest are to address fracture toughness properties analysis at room temperature and elevated temperatures (e.g. 300 degree Celsius).
4.0 Tasks to be Performed
4.1 Review the ASTM Standard Test Method for Measurement of Fracture Toughness, E-1820, and assess its applicability to small curved compact tension specimen testing of irradiated Zr-2.5Nb pressure tube material utilized by the Canadian nuclear industry. The assessment is to provide a path forward to account for the latest theoretical understanding and advances in testing equipment.
4.2 Based on the above review, answer the following questions:
a) Can one apply the ASTM Standard Test Method for Measurement of Fracture Toughness, E1820, to test irradiated Zr-2.5Nb pressure tube material at room and elevated temperatures (e.g. 300 degree Celsius)?
b) What are the major areas for improvement or development? Include a description with rationale of the following:
i. What areas of the aforementioned standard would need to be modified to suit irradiated Zr-2.5Nb pressure tube material testing on small curved compact tension specimens?
ii. What areas of the aforementioned standard would need to be modified to suit irradiated Zr-2.5Nb pressure tube material testing to account for the latest theoretical understanding and advances in testing equipment?
c) How should one proceed with standardizing the testing of irradiated small curved compact tension Zr- 2.5Nb specimens?
4.3 Review and summarize international practice in the following areas:
a) Fracture toughness tests on small sub-size specimens;
b) Use of the curved compact toughness specimens (CCTS) in fracture toughness tests;
c) State-of-art instrumentation and data acquisition systems; and
d) Methods for calculation and verification of the fracture toughness parameters from the test data.
4.4 Develop two (2) draft standards or draft standard appendixes under CSA or ASTM for determination of fracture toughness properties of irradiated Zr-2.5Nb pressure tube material in as-received and elevated hydrogen concentration conditions for room and elevated temperatures (e.g. 300 degree Celsius).
