Source & Intermediate Range Detectors (SRM/IRM)

GE is a technological leader in reactor startup instrumentation sensors. A typical reactor has four source range monitor (SRM) sensors and eight intermediate range monitor (IRM) sensors that are used during the startup phase of reactor operations. Our Reuter Stokes SRM and IRM sensors operate inside a dry tube installed within the reactor core and are designed to be moved in and out of the dry tube.

Features and Benefits
  • A fission-counting device that operates from below the source level to 109 nv, or approximately 10-3 percent of the rated power
  • As the reactor power level exceeds the range in which the SRM can count neutron counts individually, a drive mechanism withdraws the detector from the reactor core to a storage location below the active fuel region. Then the IRM begins to generate output and is used to control the reactor operation up to approximately 10 percent of the rated reactor power. After the power level exceeds the range of the IRM, it is removed and stored.
  • The IRM is a fission chamber that uses a voltage variance (Campbell) method and operates from 108 to 1.5 x 1013 nv, or approximately 10 percent of the rated reactor power
  • Ability to withdraw the detectors as the reactor flux exceeds the startup and intermediate range prolongs sensor life and lengthens overlap between SRM and IRM channels and IRM and LPRM channels respectively
  • The IRM sensor’s lifespan averages eight years based on 1 e17 nvt per startup/shutdown cycle and five cycles per year

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