For a given area, the values of Kc and Ic will be constant along with Ry. Since we measure Rr, the only unknown are Kj and Ij. The value of Xj can de determined once the ambient gamma spectrum ig known. Data from the manufacturer indicates an error of as much as 6 to 10% could resule if energy corrections are not made to the gross readings. The RSS-llls used in this study were calibrated at the factory using tadium sources whose calibration is traceable cto the National Bureau of Standards. Cali- bration of the instruments were also checked by EML (formerly HASL) prior to field use. Energy Dependence Corrections In the 1977 surveys, BNL used a sodium iodide detector, whose output was coupled te a multichannel analyzer. The purpose was to enable the BNL team to acquire spectra of the terrestrial background radiation at one meter above the surface. This was done at the same heighe and in the same areas where the RSS-l1ll Measurements were taken. Consequently, energy dependence factors could be cal- culated by examining the environmental gamma scan for che energies of those nuclides most predominant in the terrestrial environment. The equipment used to accomplish this part of the work was a compucing Gamma Spectrometer, Model LEA 74-008 #11 buile by Lawrence Livermore Laboratory (2). The system uses a Harshaw 5.08 cm diameter x 5.08 cm thick NaI(Tl) scintillation detector. The spectrometer can be operated from AC power or on internal batteries. Spectra are visually displayed on a CRT, and transferred to magnetic tape for storage. Using the math package with the system, each spectrum was examined in 100 XeV increments, and folded into the R2SS-L11l energy response curve to cetermine the energy dependence factors. The range of factors needed to compensate the RSS-111 response due to energy