Scenario development for the Waste Isolation Pilot Plant Compliance Certification Application

Abstract

Demonstrating compliance with the applicable regulations for the Waste Isolation Pilot Plant (WIPP) requires an assessment of the Iong-term performance of the disposal system. Scenario development is one starting point of this assessment, and generates inqui~about the present state and fiture evolution of the disposal system. Scenario development consists of four tasks: (i) identi&ing and classifying features, events and processes (FEPs), (ii) screening FEPs according to well-defined criten~(iii) forming scenarios (combinations of FEPs) in the context of regulatory performance criteria and (iv) specifying of scenarios for consequence amdysis. The development and screening of a comprehensive FEP list provides assurance that the identification of significant processes and events is complete, that potential interactions between FEPs are not overlooked, and that responses to possible questions are available and well documented. Two basic scenarios have been identified for the WIPP: undisturbed performance (IIP) and disturbed performance (DP). The UP scenario is used to evaluate compliance with the Environmental Protection Agency's (EPA's) Individual Dose standards and accounts for all natural and waste-and repository-induced FEPs that survive the screening process. The DP scenario is required for assessment calculations for the EPA's cumulative release standard (Containment Requirements, 40 CFR~191.13) and accounts for disruptive future human events, which have an uncertain probability of occurrence, in addition to the UP FEPs.

Scenario development for safety assessment in deep geologic disposal of high‐level radioactive waste and spent nuclear fuel: A review

“…Using the FEP and scenario approach for an application besides radioactive waste disposal may require development of new FEP lists or adaptation of existing ones. The development of FEP lists is considered elsewhere, as there already exist generic international lists (NEA, 2000, 2019), host‐rock‐specific lists (Freeze et al., 2020; Lommerzheim et al., 2018; Mazurek et al., 2003), and country‐ or program‐specific lists (Freeze, 2002; Galson et al., 2000; Locke & Bailey, 1998; NEA, 2013b). The NEA has developed a generic international FEP database for radioactive waste disposal, which compiles the international experience of repository projects with different waste inventories and different host rocks (NEA, 2000, 2019).…”

“…Scenarios are a key part of the overall safety assessment (SA) to formalize, plan, and assess a complex decision process considering significant uncertainty. Scenarios have a key role in the development of a postclosure safety case for geologic repositories for the permanent disposal of radioactive waste (Andersson, 1989; Billington & Bailey, 1998; Cranwell et al., 1982; Galson et al., 2000; Hansen et al., 2014; NEA, 2001; Tosoni et al., 2018), strategic businesses planning (Bradfield et al., 2005; Schoemaker, 1993; Wright & Goodwin, 2009), extreme flood and drought preparation (Reilly & Willenbockel, 2010), CO 2 sequestration (Paulley et al., 2011; Yamaguchi et al., 2013), environmental remediation (Meyer et al., 2007), flood risk assessment (Jonkman et al., 2008), hydraulic fracturing (Tatomir et al., 2018), geothermal development (Lowry, 2021), climate model prediction (Hawkins & Sutton, 2009; IPCC, 2000), and climate intervention analyses (Wheeler et al., 2023).…”

Scenario Analysis for the Safety Assessment of Nuclear Waste Repositories: A Critical Review

“…United States 1996 a Howard et al, (22) Galson et al, (23) Helton et al, (24)(25)(26)29) Berglund et al, (27) Stoelzel et al (28)…”

“…In consequence, the future evolution of the disposal system, or the system evolution, is determined by the joint evolution of the FEPs. (23) As discussed in Section 1, and as we shall elaborate in Section 2.3.3, there is aleatory uncertainty about system evolution. This uncertainty can be characterized by generating different scenarios.…”