Page 232 - Dynamics and Control of Nuclear Reactors

16.6 High temperature reactor instrumentation 231

Type-K). Other advanced temperature systems, such as Johnson noise thermometers
or pyrometers, might augment thermocouple measurements.
Not only are the temperatures high, but the reactor characteristics also determine
sensor requirements. In-core and primary loop sensors must be made of materials
that are chemically compatible with the coolant (especially liquid metal in LMFBRs
and molten salt in MSRs). Chemicals present in the reactors dictate the need to mon-
itor chemical processes and sensors must be capable of operating in the chemical
environments.
The speed with which reactor conditions can change in a reactor determine the
required speed of response of sensors or lack thereof.

16.6.1 Liquid metal fast breeder reactor (LMFBR) instrumentation

Instrumentation needed for LMFBRs is influenced by the plant characteristics (very
high temperature, chemically active coolant, fast neutron spectrum and fast response
in a transient). Following is a list of instrumentation used in a typical sodium fast
reactor (SFR) [9–11].

• Neutron power (in-core and ex-core neutron detectors)
• Primary pump (sodium) flow rate and pump differential pressure (ΔP)
• Cold pool sodium temperature
• Hot pool sodium temperature
• IHX pump (sodium) flow rate and pump differential pressure (ΔP)
• Pump motor electrical signatures
• Core inlet plenum sodium temperature
• Core outlet plenum sodium temperature
• Control rod position/reactivity
• IHX primary sodium outlet temperature
• IHX secondary sodium inlet temperature
• Steam generator sodium inlet temperature
• Steam generator steam temperature
• Superheated steam pressure
• Steam flow rate to the turbine
• Feedwater flow rate to the steam generator
• Feedwater temperature
• Condenser pressure, condenser coolant inlet and outlet temperatures
• Feedwater heater water level and inlet/outlet temperatures.
• High-pressure and low-pressure extraction steam flow rates.

These measurements span the following systems: reactor core, primary heat transport
system, intermediate heat transport system (IHTS), steam generator system (SGS),
and balance-of-plant (BOP). Depending on the system design, other measurements
and corresponding instrumentation would be necessary.