Neutron Measurements for Thermoluminescence Dosimeter and Electronic Personal Dosimeter Algorithms at Primary Shield Penetration of Unit 1 Pressure Water Reactor at South Texas Project Nuclear Operating Company

R.A. Aguilera; W.T. Bullard; L.M. Earls; J.A. Myers; L. Stoicescu; and G.E. Williams (South Texas Project Nuclear Operating Company)

South Texas Project Nuclear Operating Company (STPNOC) detected a small primary coolant steam leak inside the biological shield wall via use of a video robot. Isolation of the leak proved to be a Health Physics challenge since dose rates and neutron spectrum were unknown in that area at 100% power and instrumentation response was undetermined. The task was to determine the radiation level and correction factors for Panasonic UD-802 Thermoluminescence Dosimeters (TLD’s) and Siemens’s Electronic Personal Dosimeters for Neutrons (EPD-N) using the Far West Technology Model REM 500 neutron survey meter, Ludlum Model 12-4 polyethylene Rem-ball neutron instrument (rem ball), and Eberline Model RO-20 ion chamber. Comparison measurements between the TLD’s and EPD-N’s to the REM 500 neutron survey meter and Ludlum rem-ball were conducted with an Americium/Beryllium source and at several locations within the reactor containment building where the neutron fields were previously characterized. After appropriate corrections the Ludlum polyethylene Rem-ball agreed with the REM 500 readings within 15%. A backscatter factor was determined and applied to compensate for off-phantom dosimetry measurements. The EPD-N’s response to neutrons did not require a correction factor. Significantly, these measurements gave STPNOC a correlation between neutron survey instruments and personal dosimeters at the anticipated work location.

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