Direct reading dosemeter has been used for day-to-day radiation exposure control and management for last four decades in Indian nuclear power plants (NPPs). Recently new real time, alarm and pre-alarm on equivalent dose/dose rate, storage of dose/dose rate and maximum dose rate, user-friendly electronic active personal dosemeter (APD) has been implemented into practice for the first time at Kaiga Atomic Power Station-3&4,  of Indian NPPs. The dosemeter showed tolerance level (L) 0.1085±0.0450 compared with 0.1869±0.0729 (average±SD) for CaSO4:Dy, TL dosemeter, having narrow range trumpet curve, nil electromagnetic interference. Records of >29 000 for APD and TL dosemeter were analysed for comparasion of the measurement of the individual dose. APD followed general acceptance rule of ±25 % for dose >1 mSv. Monthly Station collective dose by TL dosemeters and APD for normal reactor operation as well as outage are found in good agreement. Operational experiences and statistical analysis support that an APD dosemeter is reasonably equivalent to CaSO4:Dy TL dosemeter. The accuracy, reproducibility and repeatability of the measurement of radiation for (137)Cs are comparable with CaSO4:Dy, TL dosemeter. Operational experience of APD during the normal operation as well as outage showed as one of the best ALARA tool for occupational dose monitoring, control, management and future outage planning.

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In the present paper, we estimated backscattering factors for the TLD and active personal dosimeters using 662 keV gamma-ray photons on a PMMA surface, which are, for the TLD, 1.12; Dosicard, 1.116; DRD, 0.99; and Saphydose, 1.073, and on a water slab phantom surface; for the TLD, 1.115; Dosicard, 1.112; DRD, 1; and Saphydose, 1.059. The backscattering factor contribution for the Saphydose is nearly half that of the TLD and Dosicard, whereas it is zero for the DRD. The DRD underestimates Hp(10) by 10.3-11.6%, whereas for the Saphydose it is 3.4-5% compared with the TLD or Dosicard. The response of the DRD to Hp(10) is nearly independent of the phantom, whereas the TLD, Dosicard and Saphydose require phantoms for calibration for personal monitoring. It is observed that the PMMA phantom contributes slightly higher backscattering compared with the water slab phantom. The backscattering factor of the selected dosimeters is comparable with ICRU tissue already reported.Keywords: air kerma / backscattering / operational quantity / ambiguity / photon and Z eff