CHAPTER 17 dose to as high as 70% of the weather-deck dose for a well-shielded location, and for a lightly shielded location, respectively. No theoretical models have been developed for estimating transit radiation from water-surface bursts, primarily because the early phenomen- ology of such bursts (that is, the magnitude and distribution of activity in the base surge) has never been reliably defined. Several theoretical models have been developed for estimating transit-radiation dose rates and doses from underwater bursts. Section 17.5.4 The “radiological model” presented in does not define the actual physical shape of the base surge, but use of the model does permit approximate calculation of transit-rad- dation doses at any specified surface location, for underwater bursts of l-to 100-KT yields. Calculated results are in good agreement with measurements taken at Shots Wahoo and Umbrella. Several methods of calculating gamma doses at shielded locations have been developed, and the method referenced in Section 17.55 1s one of the most recent. Certain features of several earlier systems are incorporated, along with the latest theoretical efforts to account for the spectral distribution of the various energies at the exposure point and for the scattering character- istics of the various energies involved and the media penetrated. co Experiments have been carried out recently at USNRDL, to investigate the penetration of an aircraft carrier by a distant gamma-ray source.° Doses were measured.in many velow-decks spaces of a light aircraft carrier, using @ CoO source with various angles of incidence at dis- tances of 80 to 100 ft, to simulate the radiation from a base surge. Such experiments permitted measurements of the attemuation of the gamma radiation, by ship shielding. No comparisons have yet been made between these experimental results and theoretically calculated resulte. 17-69