Report on a study of the feasibility of use of the COLUMN2 computer program in a probabilistic risk assessment code

This report contains the results of a feasibility study carried out on the COLUMN2 computer program to assess its potential for use in time-dependent probabilistic risk assessment code for radiological assessment purposes. COLUMN2 is a program which provides predictions of nuclide transport in a one-dimensional geosphere configuration using a simple Ksub(d) approach for sorption. A moving grid numerical solver is used and the program is therefore potentially capable of handling time-dependent parameters. The reported work covers aspects of code acquisition, loading, theory and structure, necessary code modifications and testing, the last aspect including two documented test cases from the COLUMN2 manual and verification tests derived from international comparison exercises. Recommendations are made as to the required code development of COLUMN2 in order that the code is capable of fulfilling its prime role as defined by the System Design Working Group in a pra code. (author)