GROUP 1 Universal SW for PRA

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Ben Caroccio Mission Evaluation Room (MER) operations scenario: An on-orbit anomaly has occurred, flight control manager’s decision making: Available information: FMEA, work-arounds, relevant flight rules Hazard Report Critical Item List PRA RBD (Reliability Block Diagram) PRACA (problem report and corrective action) GOAL: Have this information linked(?) together!* Searchable by users. Group 1: Pete Rutledge, Joanne Dugan, Ben Caroccio, Martin Feather, Michael Stamatelatos, Jeff Rusick, Shantaram Pai *Proprietary information a problem? Not an issue on shuttle and station (most experiments on) Make available representative information for us to look at!


Joanne Dugan Standardizing PRA+ tool information exchange QRAS + Saphire + Galileo (dynamic fault trees, specific kind of FT’s) E.g., incorporate dynamic fault trees – Mathematics of? Conceptually? Software? commercialization? / licenses / IP etc. Basic of the math is quite similar between S & Q, but algorithms different. Use of approximations, cut sets vs BDDs, etc. Dynamic fault trees (just a fault tree, note) can use Markov chains – does it make sense to plug in a dynamic fault tree within the other tools, and if so how solve it? Very different packages, methodologies, stakeholders, so v. difficult. What’s our plan for trying to integrate these together? 3 separate fault tree representations exist, which are similar; some pieces of translation have been done (e.g., S->G, S->Q compatible textual representations) If there were a standard rep for FT? Galileo is internally structured as a set of editors, viewers, analyzers (cf ECS RTSAD); CodeR Engineering of Complex Systems program for early conceptual design phase NASA PRA procedures guide – desired universal NASA methodology


PRA - Design Extraction from design information: Parse FMEA output to isolate structure? Need more design information to be able to extract FMEA, etc; JD’s extraction from UML diagrams. Danger: Still need for qualified engineers to do the FEMAs, not auto from UML? Virtual “iron bird” for e.g., station w/ PRA, HA, etc. - Mark Shirley later this week? Master tool for real-time flight support!


Pete Rutledge re PRA tools in NASA: Saphire default standard tool for PRA QRAS has been under development, version 1.7 released in 2003, with training class UMD working with i/o of Saphire models into/out of QRAS (JD et al same w/Galileo) Cross-center usage Futron may have done FEMA … PRA manually PRA results and makeup. NASA PRA procedures guide – desired universal NASA methodology JD: e.g., mean and standard deviation example difference between QRAS and procedures guide! BC: vision of a user friendly tool for, e.g., advice, what-ifs, … much data exists, many flight rules and procedures, safety analysis folder, FEMA folder, … individual knows how to access them, but need it fast, accurate to support flight; single tool w/ quantitative & qualitative data, searchable by the average user. RBD provides association of h/w across subsystem interfaces Need FEMA info & Hazard report man machine info integrated into PRA Master tool for real-time flight support! MS: PRA package combines much of this, but maybe not FMEA, HA; Air force 15 years ago started on this track? JR: virtual “iron bird” for e.g., station w/ PRA, HA, etc. - Mark Shirley (!) Galileo + QRAS + Saphire DDP + Galileo ECS: risk-based design in early phase of mission design


Goal: Examples of HRs FMEA, FTAs, plus scenario illustrating need for search sufficient to motivate responders to be able to fulfill these needs! Operations room scenario High-heat exchanger has failed (gone below required PSI level so not providing proper cooling to ORUs); pull up PRA with fault tree illustrating series of events to cause failure, and quantification numbers (was this well within the expected failure rate? If not, then …?) FMEA explains in text L what failed,how cause, procedures, flight rules, history of previous related PRACA (problem report and corrective action) reports (which include both cause and mitigation), criticality of items, RBD would show flowchart and level of cross interface, linked to PRA, showing dependency of a system or subsystem on an ORU (orbital replacement unit) Redundancy in thermal control system allows functions to continue, but then operating in degraded state. E.g., on station, may be able to delay experiments. Galileo + QRAS + Saphire DDP + Galileo ECS: risk-based design in early phase of mission design Early stage influence: Integrating Design and Reliability tools, which are typically done by separate groups; need more open channels of communication, design env. with reliability and safety requirements as part of the design proess, NOT an assessment function.

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