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SRM 501™

Source Range Monitor

Start-up channel used with boron-lined proportional counter for ex-core neutron flux monitoring.

Tag Features

  • Qualified to perform category A functions according to IEC 61226 and KTA 3505 (for safety-related instrumentation)
  • Seismic qualification (IEEE 344 and KTA 3505)
  • Available with B-10 detectors of various sensitivities
  • High reliability of the B-10 detector for high temperature application
  • Large measurement range
  • Signal filtering with adaptive time constant
  • Calibration to neutron flux signal or reactor power (nv, %FP)
  • Calculation of the relative flux change rate (reciprocal of the reactor period) or rate of change of reactor power (in decade/min)
  • Linear and/or logarithmic analog outputs
  • Generation of analog and binary outputs for the reactor protection system
  • Built in test signal generators (remote activation possible)
  • Optional: reactimeter


The source range SRM 501 monitor forms part of the digital Neutron Flux Monitoring Systems (NFMS) proTK™ product line. It is used, in combination with boron-lined proportional counters (B-10 detector), for ex-core neutron flux monitoring in the start-up range.

The associated DAK 250-i™ processing unit has been designed and is qualified (in hardware and software) to meet category A requirements, applicable at the level of the reactor protection system.

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