RSICC CODE PACKAGE CCC-522

 

1.   NAME AND TITLE

VARSKIN 3:      Computer Code System for Assessing Skin Dose from Skin Contamination, Version 2.2.0.

 

2.   CONTRIBUTOR

Colorado State University, Fort Collins, Colorado.

 

3.   CODING LANGUAGE AND COMPUTER

Fortran and Visual Basic; Pentium (C00522PC58604).

 

4.   NATURE OF PROBLEM SOLVED

VARSKIN 3 calculates the radiation dose (gamma and beta) to skin from radioactive contamination of skin or protective clothing. It is a modification of VARSKIN MOD 2 and was designed to operate in a Windows® environment.  The new code is significantly easier to learn and use than the previous release and includes numerous corrections and enhancements that are noted in the User Manual. Backscatter correction and gamma dose models were upgraded. The default area for skin dose calculations was changed to 10 cm² to conform to recent regulatory guidance. The input data file for VARSKIN Mod 2 was modified to reflect current physical data, to include the contribution to dose from internal conversion and Auger electrons, and to reflect a correction for low-energy electrons. In addition, the computer code SADDE (Scaled Absorbed Dose Distribution Evaluator) Mod 2, was incorporated into Varskin 3, thus eliminating the need for additional input from the user.

VARSKIN3 calculates the dose to 10 cm² as a default for comparison to the 50 rad limit and also contains the capability of calculating the dose to 1 cm² to evaluate an exposure against the eye dose limit.  The dose is computed at any depth in skin or in a volume of skin from point, disk, cylindrical, spherical, and slab (rectangular) sources.  Doses from multiple sources can be computed.  

 

5.   METHOD OF SOLUTION

VARSKIN 3 uses improved algorithms for calculating skin dose that take advantage of the increased power of modern personal computers that improve the overall accuracy of the calculations. Source density is reset to 0.001 g/cm³ when point and 2-D models are used for calculations.  The backscatter correction model has been expanded to include 3-D sources and is applied regardless of the dose-averaging area.  The minimum distance between the source and target was reduced from 0.27 μm to a value of  0.01 μm.  Sixty radial dose calculation points are used on the target area instead of 26 points used in VARSKIN Mod 2. Once the 60-point distribution is calculated, the distribution is evaluated at 10,000 points to increase the reliability of the calculation. VARSKIN 3 evaluates the dose at 50 depths for volume averages instead of 20 points. Once the 50 point distribution is calculated, the distribution is evaluated over 10,000 points to increase the accuracy and eliminate oscillating results. VARSKIN 3 calculates the backscatter correction factor at each of the 50 depths in the volume averaged dose distribution.  In VARSKIN 3, the capability of adding multiple radionuclides was eliminated and a more accurate method of creating library files was incorporated. An improved gamma dose model was incorporated into VARSKIN 3 that calculates the gamma dose to any area smaller than 10 cm².  BETADATA.DAT is no longer used as the input file for VARSKIN 3. Each user builds a library that contains only the radionuclides of interest to that user. The new data files contain physical data for the average energy, maximum energy, and yield based on data generated by the computer code NUCDECAY (Oak Ridge National Laboratory, 1995, distributed by RSICC as DLC-172), which uses data published in ICRP 38 (1983). Further information in the library files includes data for gamma dose calculations and contribution from internal conversion and Auger electrons.

 

 

6.   RESTRICTIONS OR LIMITATIONS

See the User Manual for details on restrictions.

 

7.   TYPICAL RUNNING TIME

Run times for VARSKIN 3 vary from a few seconds to several minutes. The code is interactive.

 

8.   COMPUTER HARDWARE REQUIREMENTS

VARSKIN 3 was tested at RSICC on a Pentium IV running Windows XP with Service Pack 2.0. It was also tested with Windows 2000 SP 4. A graphics card is required.

 

9.         COMPUTER SOFTWARE REQUIREMENTS

VARSKIN 3 was developed under the Windows operating system on personal computers. Microsoft Visual Basic 6 (for the user interface) and Compaq Visual Fortran Version 6.6 compilers were used to create the executables which are included in the package. In the Version 2.2.0 release, source files were added to the package; and on-line help was implemented.

 

10.       REFERENCES

a: Included in documentation:

J. S. Durham, "VARSKIN 3: A Computer Code for Assessing Skin Dose from Skin Contamination," NUREG/CR Draft (November 2004).

 

b: Background information:

R. J. Traub, W. D. Reece, R. I. Scherpelz, and L. A. Sigalla, "Dose Calculation for Contamination of the Skin Using the Computer Code VARSKIN," NUREG/CR-4418, PNL-5610, Pacific Northwest Laboratory (August 1987).

J. W. Poston and D. M. Busche, "Software Review: VARSKIN-MOD1," Health Physics 58(5), 665.

W. D. Reece, S. Miller, and J. Durham, "SADDE (Scaled Absorbed Dose Distribution Evaluator)," NUREG/CR-5276, PNL-6761 (January 1989).

J. S. Durham, “Errata for NUREG/CR-5873, VARSKIN MOD 2 and SADDE MOD 2: Computer Codes for Assessing Skin Dose from Skin Contamination,” Health Physics Society’s Newsletter, 10, 31-32 (October 1994).

J. S. Durham, “Further Errata for NUREG/CR-5873, VARSKIN MOD 2 and SADDE MOD 2,” Health Physics Society’s Newsletter, 12, 18 (December 1994).

 

11.       CONTENTS OF CODE PACKAGE

Included are the referenced document in 10a.and the source code, executables and built-in data libraries. The package is transmitted on a CD.

 

12.       DATE OF ABSTRACT

December 1987, revised February 1993, March 1995, October 2004, November 2004.

 

KEYWORDS:               BETA-RAY; KERNEL; RADIOACTIVITY; ENERGY DEPOSI­TION; MICROCOMPUTER