NFME pilot channel

Project goals:

  • input of NFME pilot channel into pilot operation;
  • confirmation of correspondence of detection devices’ characteristics to the requirements of relevant Technical Assignments;
  • check of algorithms of functioning and software of signal processing equipment of detection devices;
  • monitoring of NFME pilot channel operation during power Unit operation.

Composition of the project:

  • detection device UDPN-01 (references to relevant items of chapter “Products”) (detection device on the basis of ionization fission chamber KNK15, the range of thermal neutron flux density monitoring in channel of ionization chamber (IC) – from 10 to 1.0106 cm-2s-1 and from 1.0108 to 1.51010 cm-2s-1 at the dose rate  of background gamma-radiation absorbed in the air  at the place of detection unit location of not more than 1.0104 Gyh-1 (1.0106 Rh-1) at nominal power of reactor plant;
  • detection device UDPN-02 (detection device on the basis of boron compensation ionization chamber KNK53M, the range of thermal neutron flux density monitoring in IC channel – from 1.0105 to 1.51010 cm-2s-1 at the dose rate of background gamma-radiation absorbed in the air equal to 1.0104 Gyh-1 (1.0106 Rh-1) ;
  • detection device UDPN-03 (detection device on the basis of boron proportional neutron counters SNM11, the range of thermal neutron flux density monitoring in IC channel – from 4.010-2 to 4.0103 cm-2s-1 at the (exposure) dose rate of background gamma-radiation absorbed in the air at the place of BDPN location is not more than 1.0 Gyh-1 (1.0102 Rh-1);
  • auxiliary unit BH-01 (unit for communication of detection devices with the cabinets of NFME acquisition and processing);
  • auxiliary unit BH-02 (unit for communication of detection devices with the cabinets of NFME acquisition and processing);
  • processing unit BPM-06 (intended for processing of input signals from UDPN, generation of setpoints, generation of protection, control and informational signals in the whole range of power and period monitoring, monitoring of reactivity, monitoring of refueling, as well as monitoring of good condition, and transfer of all the data via serial channel to work station WS - 855GSATX for subsequent analysis);
  • unit for processing of signals from detectors BOSD-K (executes the functions similar to BPM-06 by other methods (algorithms) of data processing);
  • work station WS - 855GSATX (executes the functions of automated workplace of data displaying and logging hardware). 
Structural diagram of NFME pilot channel:
Structural diagram of NFME pilot channel 

The operation of NFME channel was fulfilled during fueling, physical and power start-up, start-up experiments and operation in the plant modes. At present the pilot operation of NFME pilot channel is underway.

The document “Report on the results of WWER-440 RP monitoring during fueling, start-up and putting to power by means of pilot channel of neutron flux monitoring equipment 
AKNP-01 at power Unit No.3 of Kola NPP” is issued by the results of start-up and putting to power.

The main results of the project realization:

  • demonstration of possibility to monitor the refueling at WWER – the channel of refueling monitoring, built-up on the basis of UDPN-03, ensures the monitoring of refueling. The readings of UDPN-03 at loaded reactor exceed the background readings registered at fully unloaded fuel by 20-40 times;
  • determination of minimum sensitivity of detection device UDPN-03, necessary for monitoring of WWER-440 fuel loading (fueling);
  • confirmation of declared characteristic of WWER neutron flux monitoring equipment at power increase within the range from fully shutdown state to the level of 35% Nnom;
  • NFME channel, built-up on the basis ofе UDPN-01 and UDPN-02, ensures the monitoring of change of neutron flux density during heating of the primary circuit, elevation of АРК groups, withdrawal of boric acid at putting to minimum monitored level;
  • all the channels of NFME ranges operated correctly, switching-over between the ranges was fulfilled in due time at both – increase and decrease of RP power. Overlapping zones of ranges are equal to not less than one decimal exponent. NFME system provides the monitoring of RP related power within the whole range of its change in accordance with the project.

During monitoring of NFME operation at power Unit operation at power the following activities are undertaken:

  • determination of degree of g-background influence in NFME channel on the equipment readings in the range from 10 to 100% of nominal power;
  • periodic check of volt-ampere characteristics of detection units;
  • analysis of reaction of data processing algorithms to changes of power density at possible procedures of  reactor plant maneuvering;
  • fine-tuning of algorithms for data processing and of programs for measuring data archiving.