Baldwin TD and Hicks TW, Assessment Calculations for Human ...

0977-6Version 12 Human Intrusion Events and Exposure PathwaysIdentification and selection of the human intrusion events for assessment is discussedin Section 2 of Hicks and Baldwin (2011). The GoldSim implementation of thehuman intrusion model solves identical expressions of dose for each human intrusionevent at each grid location across the disposal facility (the model grid is discussed inSection 3). The exposure pathways evaluated for each event are summarised in Table2.1 and their incorporation into the GoldSim application is illustrated in Figures 4.1 to4.6 of Hicks and Baldwin (2011). The relevant mathematical dose expressions arepresented in Appendix B of Hicks and Baldwin (2011).Where the exposure is short-term and directly related to the event, doses arecalculated as dose from the event. Where the exposure is prolonged, doses arecalculated as annual doses. In both cases, the dose calculated is the sum of effectivedoses from external irradiation received from the event or annually, plus committedeffective doses from inhalation and ingestion of contaminated material during theevent or annually.The specification of parameter values for each human intrusion event is discussed inSection 6.2 of Hicks and Baldwin (2011) and a summary table of parameter values isprovided in Section 5.2 of this report. Note that the dose for each geotechnicalinvestigation event (B1) is calculated for a single event (borehole drilling or trial pitexcavation) at each grid location or the analysis of a single sample from each location.However, during the course of a geotechnical investigation, an engineer may beinvolved in drilling several boreholes, excavating several trial pits, or analysingseveral samples. Cases involving multiple intrusion events are described by Hicksand Baldwin (2011, §6.2). The GoldSim evaluations of dose for single events may besummed to determine the dose from multiple intrusion events.Galson Sciences Ltd 4 21 March 2011