Mission Success Starts With Safety 1 Probabilistic Risk Assessment: NASA Strategy for Capability...

Mission Success Starts With Safety

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Probabilistic Risk Assessment: NASA Strategy for Capability

EnhancementDr. Michael G. StamatelatosManager, Risk AssessmentNASA HeadquartersOffice of Safety and Mission [email protected](202) 358-1668


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Outline

• Introduction

• PRA History at NASA

• NASA PRA Capability Improvement Strategy

• On-Going Efforts


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Introduction


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PRA Simply Described

1. WHAT CAN GO WRONG ?

(DEFINITION OF SCENARIOS)

2. HOW FREQUENTLY DOES IT HAPPEN ?

(SCENARIO FREQUENCY QUANTIFICATION)

3. WHAT ARE THE CONSEQUENCES ?

RISK STATEMENT

INITIATING

EVENT

SELECTION

EVENT

SEQUENCELOGIC

DEVELOPMENT

EVENTSEQUENCE

FREQUENCY

EVALUATION

EVENT

SEQUENCE

MODELING

CONSEQUENCE

MODELING

RISK

INTEGRATION

(SCENARIO CONSEQUENCE QUANTIFICATION)


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Types of Risk and Related Consequences

S A F E T Y

E N V I R O N M E N T A L

C O S T

P R O G R A M M A T I C

O T H E R ?

C O M B I N A T I O N S ?

Deaths, injuries, illness

Contamination, loss of use

Money lost

Mission, schedule, etc.


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Risk Sources in Safety Risk Assessment

HardwareFailuresHardwareFailures

OrganizationalFactors

OrganizationalFactors

ExternalEvents,

Acts of Nature

ExternalEvents,

Acts of Nature

Human ErrorHuman Error

Increasing degreeof complexity in

modeling


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Risk Assessment & Management

Qualitative RiskAssessment•FMEA•FTA

Qualitative RiskAssessment•FMEA•FTA

Quantitative RiskAssessment•Initiating Events•Scenario Modeling (MLD, ESD, ETA, FTA)•Risk Quantification•Uncertainty Evaluation

Quantitative RiskAssessment•Initiating Events•Scenario Modeling (MLD, ESD, ETA, FTA)•Risk Quantification•Uncertainty Evaluation

Inputs

•Mission Success Criteria•Technical Data•Cost•Schedule•Management Procedures•Other

ImprovedImprovedSafety &Safety &

PerformancePerformance

ImprovedImprovedSafety &Safety &

PerformancePerformance


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Benefits of PRA

Probabilistic Risk Assessment (PRA) has proven to be a systematic, logical, and comprehensive tool to assess risk (likelihood of unwanted consequences) in modern technological applications (e.g., nuclear power, electric power generation, chemical processing industry), for:

Improving system performance & mission success Increasing safety in design, operation & upgrade Saving money in design, manufacturing, assembly and

operation


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When Should PRA Be Performed?

When important decisions must be made about complex systems under uncertainty

When information is not sufficient to comprehensively assess strengths and weaknesses of complex systems by other means

When important complex jobs must be performed successfully for the first time

In all life cycle phases of a complex system


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Brief History of PRA at NASA


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Beginning with the Challenge of Apollo...

“I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning

him safely to the earth.” -- President John F. Kennedy, May 25, 1961

Early Apollo program estimate of mission success probability was approximately 0.20--not what people wanted to hear.

On July 20, 1969, the human race accomplished its single greatest technological achievement of all time when a human first set foot on another celestial body.

5 additional successful Moon missions (out of 6 attempts) occurred between 1969 and 1972 = 6 out of 7 = 0.86 demonstrated mission success.

So much for PRA in NASA for a long time to come! Instead NASA would rely on FMEAs


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…Then Challenger

January 28, 1986, after 25 successful flights, the Space Shuttle Challenger explodes.

October 29, 1986, “Investigation of the Challenger Accident,” by the Committee on Science and Technology, House of Representatives:

“Without some means of estimating the probability of failure of the various [Shuttle] elements it is not clear how NASA can focus its attention and resources as effectively as possible on the most critical systems.”

January 1988, “Post-Challenger Evaluation of Space Shuttle Risk Assessment and Management,” by the Slay Committee:

“The Committee recommends that probabilistic risk assessment approaches be applied to the Shuttle risk management program at the earliest possible date. Data bases derived from STS failures, anomalies, and flight and test results, and the associated analysis techniques, should be systematically expanded to support probabilistic risk assessment, trend analysis, and other quantitative analyses relating to reliability and safety.”


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The Return to PRA

Dec. ‘87 -- Space Shuttle Proof-of-Concept Study Feb. ‘88 -- Space Shuttle Main Propulsion Pressurization System

PRA Nov. ‘88 -- Enhanced Hazard Analysis for Space Systems Apr. ‘89 -- Independent Assessment of Shuttle Accident Scenario

Probabilities for the Galileo Mission Jul. ‘90 -- Space Station Freedom -- External Maintenance Task

Team -- Final Report -- the “Fisher-Price Study” Dec. ‘90 -- Safety of the Thermal Protection System of the Space

Shuttle Orbiter -- Quantitative Analysis and Organizational Factors Jun. ‘91 -- 8’ High Temperature Tunnel PRA(@ LaRC) ‘92 -- Advanced Solid Rocket Motor Field Joint Case Sealing System

Leak Check vs. No Leak Check


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The Return to PRA (cont’d)

Jul. ‘92 -- Risk Assessment of the ASRM Propellant Manufacturing Facility

Jul. ‘93 -- Reliability and Requirements Analysis for Space Exploration Initiative Vehicles: Comparative Risk Assessment -- the Space Shuttle and an All Rocket Single Stage to Orbit Vehicle

Sep. ‘93 -- An Analysis of Selected Risk Factors and Uncertainties for Space Station Assembly Up to Human Tended Condition for Space Station Transition Options A1 and A2

Jan. ‘94 -- An Investigation of the Risk Implications of Space Shuttle Solid Rocket Booster Chamber Pressure Excursions

Feb. ‘95 -- PRA of the Space Shuttle -- A Study of the Potential of Losing the Vehicle During Normal Operations

And others including PRA work done in support of Ulysses and Cassini missions.


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The NASA Administrator Steps In...

July 29, 1996, the NASA Administrator, Dan Goldin:

“Since I came to NASA [1992], we’ve spent billions of dollars on Shuttle upgrades without knowing how much they improve safety. I want a tool to help base upgrade decisions on risk.”

Earlier “paper PRAs” prepared by NASA contractors would not serve the purpose.

October 1997, an early version of the NASA Quantitative Risk Assessment System (QRAS) is demonstrated to the Administrator.

February 1998, Version 1.0 of QRAS is baselined. Two other intermediate version have been tested March 2001, Version 1.6 of QRAS will be delivered. It will have full PRA

capabilities.


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Space Shuttle

» Johnson Space Center and Marshal Space Flight Center have been modeling their Shuttle elements.

» Space Shuttle Program has begun to factor risk into their Upgrades Program.


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International Space Station

1999 -- The NASA Advisory Council recommended, the NASA Administrator concurred, and the ISS Program has begun a PRA.

» First portion of PRA (through Flight 7A) delivered in Dec. ‘99; 2nd portion (through Flight 10A) expected in Dec. ‘00.

» Using the SAPHIRE software application for conducting PRA.

Objectives of ISS PRA:» Provide a quantitative look at ISS operations risk» Provide a model for future ISS safety decision-support

activities» Provide a model for safety related operations planning» Provide a model for trading marginal safety

enhancements versus cost


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Mars Sample Return Mission

Mission must meet a Planetary Protection Program criterion of <10-6 probability of Earth contamination upon return of sample

Use of PRA is being seriously considered as a means to evaluate mission compliance with the PPP criterion


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The Risk Management Picture at NASA

• NASA Procedures and Guidelines 7120.5A, “NASA Program and Project Management Processes and Requirements,” April 3, 1998

– Requires NASA Program & Project Managers to manage risk formally– We are seeing evidence of real risk management in numerous NASA

projects– Risk management is a factor in high-level program/project decision-

making• “Continuous Risk Management” training course developed and pilot-

tested on numerous NASA project teams– To be picked up by NASA’s APPL in FY 01

• Risk-Based Acquisition Management (R-BAM)– Interim rule entitled “Risk Management,” -- published in Federal

Register June 14, 2000; effective July 14, 2000– Changes NASA Supplement to the Federal Acquisition Regulations

(FAR) to emphasize considerations of risk management in the acquisition process


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Strategy for PRA Capability Enhancement


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Current PRA Status at NASA

Good News: Strong management interest and support for PRA In-house experience with traditional FMEA and

some FTA

Bad News: Scarce and scattered PRA resources (people,

tools, data) No corporate memory on PRA past work and data Inadequate communication and cooperation on

PRA among Centers and with HQ


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NASA Objective For PRA

Develop a world-class in-house capability to perform, manage, and use Probabilistic Risk Assessment (PRA) methods at NASA


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Ingredients for Success from Experience

In-house expertise to perform, manage and use PRAs to make sound decisions

In-house ownership and corporate memory of PRA methods, tools, databases and results

Lowest dependence on outside help to manage, perform, understand, and use PRA methods and results to make management decisions


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NASA PRA Capability Growth Model

Total Dependenceon ExternalConsultants

NASA is Only aCustomer of ItsPRA Projects

NASA on aPRA LearningCurve; Takes

Leadership in PRA

ConsultantsProvide Transfer

of Technology andSupport in PRA

NASA WithPRA Experts;

Manages/PerformsPRA Projects

Outside PRAConsultants JustProvide Support

Today Near-Term Long-Term

1-2 years 2-5 yearsTime frame

Role

Shi

ft

PRA Renaissance Age of PRA Enlightenment


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Essential Elements for PRA Strategy

Develop NASA personnel skilled in PRA to transfer the state-of-the-art PRA technology to

Develop/adopt NASA-wide PRA policy, procedures, computer tools

Develop, coordinate & maintain PRA databases (reliability, maintenance, initiating events, etc.)

Foster communication and cooperation of efforts throughout NASA

Integrate and coordinate PRA efforts throughout NASA


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Strategy Implementation Roles

NASA HQ Organize, coordinate and conduct awareness and practitioner

PRA training Develop PRA policy and procedures Mentor and provide specialized PRA assistance Coordinate use of PRA computer tools and consultants Manage the PRA process and oversee PRA quality

NASA Centers Work with HQ to implement PRA strategy Manage and perform PRA projects Provide local PRA expertise and support in training, consulting

and mentoring PRA projects Become local custodians of PRA data and software


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We are Up and Running ...

Initiated work on PRA policy and PRA awareness and practitioner training

Started effort on PRA Procedures Guide for aerospace applications

Began cooperation with NRC, USG agency most experience in PRA

Acquired SAPHIRE PRA computer program and conducted training at HQ and Centers; Trained 50 people to date.

Organized PRA information exchange workshop (this workshop) and the development of NASA-wide PRA working group

Started cooperation with ESA on PRA policy and procedures Planning additional workshops on PRA and on risk-based

decision making for management applications


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Conclusion

NASA needs

your help, support and cooperation

to reach our PRA objective

for the benefit of

NASA and its Centers

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Mission Success Starts With Safety 1 Probabilistic Risk Assessment: NASA Strategy for Capability...

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