Early-stage quantitative risk assessment to support development of codes and standard requirements for indoor fueling of hydrogen vehicles.

Abstract

Sandia National Laboratories is developing the technical basis for assessing the risk of hydrogen infrastructure for use in the development of relevant codes and standards. The development of codes and standards is an important step in ensuring the safe design and operation of the hydrogen fuel cell infrastructure. Codes and standards organizations are increasingly using risk-informed processes to establish code requirements.Sandia has used Quantitative Risk Assessment (QRA) approaches to risk-inform safety codes and standards for hydrogen infrastructures. QRA has been applied successfully for decades in 3 many industries, including nuclear power, aviation, and offshore oil. However, the hydrogen industry is a relatively new application area for QRA, and several gaps must be filled before QRA can be widely applied to reduce conservatisms that influence the safety requirements for hydrogen installations.This report documents an early-stage QRA for a generic, code-compliant indoor hydrogen fueling facility. The goals of conducting this activity were threefold: to provide initial insights into the safety of such facilities; to recommend risk-informed changes to indoor fueling requirements in safety codes and standards; and to evaluate the quality of existing models and data available for use in hydrogen installation QRA. The report provides several recommendations for code changes that will improve indoor fueling safety. Furthermore, the report provides insight into gaps in the QRA process that must be addressed to provide greater confidence in the QRA results.4

Overview of the DOE hydrogen safety, codes and standards program, part 3: Advances in research and development to enhance the scientific basis for hydrogen regulations, codes and standards

“…While general QRA methods are applicable to hydrogen systems, more widespread use of QRA for code revisions has previously been limited due to gaps in available data and models relevant to hydrogen systems [31,32,33,34]. More recently, researchers have found that QRA for hydrogen applications is further limited due to the variety of models required to perform a complete QRA [34].…”

“…[35,36,37,38,39,40,41] or extended QRA techniques (e.g., Bayesian Networks) [42,43] are used to model the scenarios and root causes, and various reduced-order models and CFD models are used for consequence calculations. The emergence of fast-running behavior models opens the door for use of advanced QRA approaches (i.e., dynamic PSA [probabilistic safety assessment]), including Event Sequence Diagrams [31], Discrete Dynamic Event Trees, various sampling and simulation-based QRA and PSA models [44,45,46].…”

“…QRA was used to inform separation distances in the 2011 revision to NFPA 2 [41] by establishing boundary conditions as inputs to the behavior models (described in Section 2), which in turn determined the profile of the physical hazards (heat and concentration contours). QRA was also used to address size limits of indoor fueling rooms in the 2014 code revisions [31]. NFPA2 also contains performance-based rules (chapter 5), which permit the use of analytical methods such as QRA to demonstrate that a system is as safe as or safer than a system compliant with the prescriptive requirements in the code [58].…”

Methodology for assessing the safety of Hydrogen Systems: HyRAM 1.1 technical reference manual

“…Both QRA and deterministic hydrogen behavior modeling have become valuable tools for the development and revision of hydrogen codes and standards such as NFPA 2, NFPA 55, and ISO TR-19880 [6][7][8][9][10][11][12]. However, the use of QRA in hydrogen applications currently suffers from limitations and inefficiency due to a range of factors, including wide variation in QRA and consequence modeling approaches, the use of unvalidated physics models, lack of data, and more [2,[13][14][15][16][17].…”

HyRAM V1.0 User Guide

“…For this document, the inputs are based off of a generic indoor fueling system that was designed with the National Fire Protection Association's (NFPA) requirements for hydrogen systems (NFPA 2) and industry practices. The example installation is based off of the generic indoor fueling system further documented in [1] and [3].…”