1. NAME AND TITLE OF DATA LIBRARY

SKYDATA-KSU: Parameters for Approximate Neutron and Gamma-Ray Skyshine Response Functions and Ground Correction Factors.

2. NAME AND TITLE OF DATA RETRIEVAL PROGRAMS

None; data are in the form of ASCII files; see CCC-646/SKYSHINE-KSU.

3. CONTRIBUTOR

Kansas State University, Manhattan, Kansas.

4. HISTORICAL BACKGROUND AND INFORMATION

The integral line-beam skyshine method is an effective and efficient method for performing both gamma-ray and neutron skyshine calculations for sources that are small compared to the source-to-detector distance. Critical to this method is the availability of skyshine response functions which are usually approximated by an empirical formula whose parameters are obtained by fits to accurate evaluations of the response functions. This library provides revised parameters for approximations of line-beam and conical-beam skyshine response functions for both gamma-ray and neutron sources. These new compilations allow the response functions to be evaluated with greater accuracy over greater energy ranges and over greater source-to-detector distances than do previous approximations. Moreover, the neutron and secondary-photon response functions are expressed for the first time in modern dosimetric units. Finally, approximations are provided to allow correction of the neutron concical beam response functions for the effect of the air-ground interface.

5. APPLICATION OF THE DATA

The data in this library are intended for use in calculation of skyshine doses from point gamma-ray and neutron sources with the integral line-beam method. The CCC-646/SKYSHINE-KSU package includes these data and a series of such calculational codes (SKYDOSE, SKYNEUT, McSKY) that can directly use these data for simple geometries. These data can be used in specialized codes for sources with more complex geometries or to estimate the effect of the air-ground interface.

6. SOURCE AND SCOPE OF DATA

Data in this library have been obtained by fitting the response function approximations to values of the response functions calculated, for the most part, by the MCNP code. Line-beam data are presented for gamma-ray and neutron sources, the latter including neutron and secondary-photon components. Conical-beam data are also provided for neutron sources with azimuthal symmetry. Source gamma rays may have energies between 0.02 and 100 MeV, and source neutrons may have energies between 0.01 and 14 MeV. The maximum source-to-detector distance is 3000 m for gamma photons below 10 MeV and 1500 m for photons between 10 and 100 MeV. Data for neutron response functions are valid to 2500 m. Skyshine doses for photon sources are expressed in air-absorbed rad while doses for neutron sources are in dose equivalent. Specifically, the following three dose equivalents (Sv/neutron) are used: (1) the effective dose equivalent for AP irradiation of an anthropomorphic phantom, (2) the dose equivalent at 10 mm into the ICRU sphere for isotropic (ISO) irradiation, and (3) the dose equivalent on the principal axis at 10 mm depth for irradiation of the ICRU sphere by a plane parallel beam (PAR). Fluence-to-dose conversion factors are from ICRP Report 51, but do *not* include the factor of 2 increase in the neutron quality factor recommended at the 1985 Paris meeting of the ICRP.

7. DISCUSSION OF THE DATA RETRIEVAL PROGRAM

Not applicable.

8. DATA FORMAT AND COMPUTER

All data are in standard ASCII files.

9. TYPICAL RUNNING TIME

Not applicable.

10. REFERENCE

J. K. Shultis, R. E. Faw, A. A. Gui and R. C. Brockhoff, "Approximate Beam Response Functions for Gamma-Ray and Neutron Skyshine Analysis," KSU Report 271 (June 1995).

11. CONTENTS OF LIBRARY

Included is the referenced document and one 3.5-in DS/HD (1.44MB) diskette written in DOS format containing multiple ASCII files of the data.

12. DATE OF ABSTRACT

July 1996.