Nuclear power plants - Instrumentation important to safety - Temperature sensors (in-core and primary cooling circuit) - Characteristics and test methods
This International Standard is applicable to general aspects of system and component design,
manufacturing and test methods for temperature sensors used in-core and for the primary
coolant circuit in nuclear power reactors.
These sensors include thermocouples and RTDs (Resistance Temperature Detector–RTD).
Emphasis is placed on the features specific to the nuclear application and recommendations
concerning components and sensors are made only when they relate to the containment of
such components within the reactor primary envelope and/or in high radiation fields.
The conditions imposed by reactor use are often different from those which occur in nonnuclear
applications. Parts of the in-core system may be located in very severe environments.
Exposure to high neutron and gamma radiations is liable to cause error due to nuclear
transformations, heating and structural changes, and to affect the mechanical and electrical
properties of the equipment so that extra care has to be taken in the standards adopted for
installations and in the choice of materials.
Furthermore, design consideration needs to be given to the effects of high environmental
pressure, high temperature, temperature gradients and temperature cycling as well as to the
way in which the temperature measuring system could influence the safety or economic
performance of the reactor.
The consequences of nuclear conditions for temperature sensors lead to strong requirements
regarding qualification.
This standard deals with specific requirements for nuclear applications of temperature
sensors. It has two purposes:
a) to provide a guide which will help to ensure that the reactor conditions do not damage the
temperature sensors;
b) to ensure that the in-core temperature measuring system and the sensor installation do
not prejudice the safe operation and the availability of the reactor.
Statements of general applicability are made but detailed consideration is restricted to
thermocouples and RTDs.