ASTM E3536_E3536M-26
Standard Specification for Compacted Mineral-Insulated, Niobium-Sheathed, High Temperature Irradiation Resistant Thermocouples
| Standard number: | ASTM E3536_E3536M-26 |
| Released: | 01.04.2026 |
| Status: | Active |
| Pages: | 9 |
| Section: | 14.03 |
| Keywords: | junction; metal-sheathed; moisture seal; sheathed thermocouples; termination; thermocouple; thermoelement; HTIR-TC; |
| ASTM number: | ASTM E3536/E3536M |
1.1 This specification covers dimensional and material requirements for compacted, mineral-insulated, niobium-sheathed, high temperature, irradiation resistant thermocouples (HTIR-TC) with one HTIR-TC thermoelement pair. These types of thermocouples are suitable for high neutron fluence, up to 1022 n/cm2, and a high temperature, up to 1600 °C [2912 °F].
1.1.1 This specification exceeds the temperature limitations of Specification E235/E235M for Type K and N. When nuclear applications are above 1260 °C [2300 °F] this standard should be considered.
1.1.2 This specification defines the diameter of the HTIR-TC MIMS cable as ranging from 0.059 in. [1.5 mm] to 0.062 in. [1.6 mm] to accommodate the nuclear fuel pin size and compactness. This has been found to be the optimal diameter for this application without compromising reliability of the sensor but to fit appropriately inside the fuel pin.
1.1.3 This specification was prepared to detail requirements for HTIR-TCs for use in nuclear environments, but they can also be used for laboratory or general commercial applications where the environmental conditions exceed normal service requirements. The intended use of the HTIR-TC in a specific nuclear application will require an evaluation of the compatibility of the thermocouple, including the effect of the temperature, atmosphere, and integrated neutron flux on the materials and accuracy of the thermoelements in the proposed application by the purchaser.
1.2 This specification describes processing, testing, and quality assurance requirements for HTIR-TCs as well as optional supplementary tests.
1.3 Provisions are made for selecting the type of thermocouple or thermoelements, alumina (Al2O3) insulation or other appropriate insulator material, and niobium (Nb) sheath material. Provisions are also made for selecting a transition or termination.
1.4 The values stated in inch-pound units or SI (metric) units may be regarded separately as standard. The values stated in each system are not the exact equivalents, and each system shall be used independently of the other.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.