Performance Assessment Software

The FANFARE (FEP Analysis For Application to Risk Evaluation) computer program is designed to assist in the analysis and documentation of the features, events and processes (FEPs), and their mutual interactions, that are considered relevant to the modelling of a radioactive waste disposal facility. Although the initial version of the program has been designed with repository performance assessments in mind, it is clear that such a tool would be useful in any situation where the analysis of different future scenarios is important. This is because the formation of such scenarios would require the identification and documentation of the different factors
from which the scenarios could be formed, and the ways in which they interact.

FANFARE is specifically designed to allow interactive modifications to a database; that is, group sessions can be held in which members can discuss specific issues, and then pass on their opinions to a FANFARE operator, who can immediately enter this information into the database. It is during such interactive sessions that FANFARE is seen to its best advantage.

Software to support quantitative assessment of the long-term safety of radioactive or toxic waste facilities

Highly flexible programs (verified over a number of years in international exercises) and extensive scientific knowledge gives the ability to tailor to customer requirements

Note that the intellectual property rights in MASCOT, MOP and HINDSITE are owned by UK Nirex Limited

Our products include:

the probabilistic assessment code MASCOT and its output processor MOP;
FANFARE, a code designed to assist with analysis of FEPs (Feature, Event and Processes) and scenario development;
HINDSITE, evaluating risks from possible future human intrusion at a repository site;
a suite of software for modelling groundwater flow and contaminant transport in porous and fractured rocks;
a range of programs that can model the evolving chemistry of the waste, including HARPHRQ for geochemical speciation, CHEQMATE for coupled chemistry and transport, CAMLE for corrosion and GAMMON for gas generation;
ENTWIFE, a powerful finite-element code for solving non-linear problems, which in the radioactive waste arena has been applied to ice-sheet movement;
a database of thermodynamic constants (HATCHES) developed and maintained to rigorous QA standards.

Close Overview

The HINDSITE (Human Intrusion at a Nuclear waste Disposal SITE) program has been developed to evaluate risks from human intrusion into a radioactive waste disposal facility. The large uncertainties in long-term future human behaviour force HINDSITE to generalise exposure scenarios. The program simply provides a tool for the rapid evaluation of exposures and risks associated with intrusion, based on a range of simple analytical assessment models.

To date, applications of HINDSITE have addressed two primary exposure scenarios:

handling by a geotechnical worker of contaminated material that has been extracted from a borehole in the vicinity of the repository;
occupation of land contaminated as a result of previous intrusions associated with borehole drilling in the vicinity of the repository.

Program outputs are the conditional doses associated with the occurrence of an intrusion event. These are translated into individual risks based on a given annual probability of borehole drilling in the vicinity of the repository.

MOP performs standard statistical processing, such as the calculations of means, standard deviations, confidence intervals.MOP can produce a variety of graphical presentations, including

line plots of scalar quantities against time;
cumulative or histogram portrayals
of variate distributions,
scatter plots of one variate against another,
other special plots associated with sensitivity analysis.

As well as analysing the quantities calculated by MASCOT, MOP can be used to define new dependent variables.

Both MASCOT and MOP have been developed on large main-frame computers, and are currently used for large jobs on the Silicon Graphics PowerChallenge supercomputer at Harwell. However, MASCOT has also successfully been ported to a number of workstations, and to a PC. The lower powered computing platforms are suitable for the deterministic mode of operation, while large-scale probabilistic runs are best suited to a high-end workstation or a supercomputer.

MASCOT is a probabilistic safety assessment (PSA) program for analysing the performance of radioactive waste repository systems, subject to uncertainties in the parameters of the models. It can be run either in probabilistic mode, randomly sampling from probability distribution functions (PDFs) for the parameters, or in deterministic mode, using fixed parameter values.

The system model is built up from sub-models, interconnected in a general network. The models presently available include several for release of radionuclides from the repository, models for geosphere transport in one dimension, based on either a porous medium or a fracture network representation, and a range of alternative biosphere models.

In MASCOT, the sub-model solutions are generally performed in the Laplace-transform domain, resulting in high efficiency and accuracy, but excluding problems where parameters vary with time.

MASCOT's input commands are particularly flexible. They allow specification of parameters using algebraic expressions, interpreted at run-time. This gives great flexibility of model specification, and permits correlations between variable parameters to be imposed.

A wide range of standard PDFs is built in. Users may accelerate convergence of statistical measures such as mean doses by using the Importance Sampling method.

When operating in probabilistic mode, MASCOT calculates the raw results of many randomly-selected realizations of the system. Statistical analysis of the results, and graphical presentation in a variety of forms, is carried out by the companion post-processor program MOP (MASCOT Output Processor).