A Foundation for Root Cause Analysis-( ) William R. Corcoran, Ph.D., P.E. Nuclear Safety Review Concepts Corporation © 2011 W. R. Corcoran, NSRC Corporation,

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Topics Background Facts Suggestion © 2011 W. R. Corcoran, NSRC Corporation,

7 Root Cause Analysis? Root Cause Analysis is any structured approach to identifying the factors that resulted in the nature, the magnitude, the location, and the timing of the consequences of one or more past events in order to identify what conditions, behaviors, actions, and/or inactions, need to be changed to prevent/reduce recurrence of similar consequences, when adverse, and to identify the lessons to be learned to promote the achievement of better consequences. COMMENT: A given root cause analysis can be successful or unsuccessful. It can be superficial or insightful. It can be honest or dishonest. As long as it is a structured approach with the intent given above it would be fairly classed with other root cause analyses. © 2011 W. R. Corcoran, NSRC Corporation,

A Purpose of RCA © 2011 W. R. Corcoran, NSRC Corporation,

What’s a Problem? A gap between what ought to be and what is.

Some Examples of “What is.” NicknameNatureMagnitudeLocationTiming Chernobyl Bhopal Hindenburg BP Deepwater © 2011 W. R. Corcoran, NSRC Corporation,

“What is” Puzzlers What are the relevant statements of “what is” for a given event? Which statements of “what is” should be investigated? Which “what is” should be investigated first? © 2011 W. R. Corcoran, NSRC Corporation,

Fact One: The “What is” resulted from factors The “What is” is an effect. A synonym for “effect” is “phenomenon.” A factor is something that affected an effect. Factors include conditions, behaviors, actions, and/or inactions. If a condition, behavior, action, or inaction did not affect any property of the effect, e.g., the “what is”, then it wasn’t a factor of the effect. © 2011 W. R. Corcoran, NSRC Corporation,

Harmful Effects (Four Factor Essences) Harmful Effect Condition Direct Factor(s) Behavior Direct Factor(s) Action Direct Factor(s) Inaction Direct Factor(s) © 2011 W. R. Corcoran, NSRC Corp., Factor essences are not mutually exclusive.

Fact One-Elaboration “The “ought to be” resulted from factors as well. One strategy for solving the problem, i.e., closing the gap, is to change the “ought to be.” © 2011 W. R. Corcoran, NSRC Corporation,

Fact Two: The “What is” has properties A “property” is a condition of reality. “Attribute” is a synonym for “property.” The properties of an effect include: –Nature –Magnitude (bigness, badness, spread…) –Location –Timing (beginning, end…) © 2011 W. R. Corcoran, NSRC Corporation,

Fact Three: The “What is” directly resulted from direct factors. A “direct factor” is a factor that affected the effect without any intervening factors. “Proximate” and “immediate” are synonyms for “direct.” “Intermediate Factor” is a synonym for “intervening factor.” © 2011 W. R. Corcoran, NSRC Corporation,

Harmful Effects (Factor Building Block) Harmful Effect (Consequence or Factor) Direct Factor 1 Direct Factor 2 Direct Factor 3 Direct Factor … Direct Factor … © 2011 W. R. Corcoran, NSRC Corp.,

Fact Four: The direct factors explain all of the properties. The properties explained by the direct factors include the: –Nature –Magnitude (number, bigness, badness, intensity, seriousness…) –Location –Timing (beginning, end…) If the identified direct factors do not explain the properties, then one or more direct factors are missing. © 2011 W. R. Corcoran, NSRC Corporation,

Harmful Effects (Four Property-related Factors) Harmful Effect Direct Factor(s) Affecting Nature of Effect Direct Factor(s) Affecting Magnitude of Effect Direct Factor(s) Affecting Location of Effect Direct Factor(s) Affecting Timing of Effect © 2011 W. R. Corcoran, NSRC Corp., Factor types are not mutually exclusive, but they all must be there.

Fact Five: The direct factors include four types of “involvement” factors. The situation for the effect was set-up. The creation of the effect was triggered. The effect was as bad as it was. The effect was not any worse than it was. © 2011 W. R. Corcoran, NSRC Corporation,

Harmful Effects (Four Factor Involvement Types) Harmful Effect Vulnerability (Set-up) Trigger ExacerbationMitigation © 2011 W. R. Corcoran, NSRC Corp.,

A Barrier Model Yet another legitimate perspective?

THREATBARRIER THE BASICS OF BARRIER ANALYSIS BARRIER: Anything that has the effect of (or is intended to ) reduce the probability and/or consequences of the effect of a threat on a target. (Notice that a barrier is only defined with respect to both a threat and a target.) TARGET © 2011 W. R. Corcoran, NSRC Corp.,

Fact Six: The direct factors include the barrier analysis factors. There must have been something that could be harmed. (A “target.”) There must have been something that could harm the target. (A “hazard” aka “threat.”) The target and the hazard must have been in the same place. They must have been there at the same time. There must have been no barrier that effectively protected the target from the hazard. © 2011 W. R. Corcoran, NSRC Corporation,

Harmful Effects (Barrier Analysis Elements) Harmful Effect (Vulnerable) Target Hazard/ Threat Co-locationSimultaneity No Effective Barriers © 2011 W. R. Corcoran, NSRC Corp.,

“No Effective Barrier” Puzzlers How many missing and ineffective barriers make up the “no effective barrier?” Which missing and ineffective barriers should be included? Which missing and ineffective barriers should be investigated? Which missing and ineffective barriers should be investigated first? © 2011 W. R. Corcoran, NSRC Corporation,

Fact Seven: As the investigation goes deeper each factor becomes a “what is” and the above apply. This implies a tightly linked, evidence- based, hierarchical factor-effect tree-like structure. That structure allows the deepest factors to be traced up to the highest “what is.” © 2011 W. R. Corcoran, NSRC Corporation,

Factor X Direct Factor Direct Factor Direct Factor Direct Factor Intermediate Factor Deeper Intermediate Factor Root Factor

Fact Eight: Favorably addressing any harmful factor favorably affects everything above it. “Favorably address” includes: ameliorate, remove, improve, correct, contain, reduce, dilute, and the like. No matter how deep or shallow an investigation with this foundation goes it will reveal harmful factors that if favorably addressed will aid in preventing the recurrence of a problem and/or reducing the severity of its future recurrence. © 2011 W. R. Corcoran, NSRC Corporation,

Fact Eight-Elaboration The deeper an investigation with this foundation goes the more harmful factors it will reveal-- that if effectively addressed will aid in preventing the recurrence of a problem and/or reducing the severity of its future recurrence. Allowing any harmful factor to go unaddressed is to predispose some future event. © 2011 W. R. Corcoran, NSRC Corporation,

Fact Nine: Unfavorably addressing any mitigating factor allows adverse recurrence of everything adverse above it. “Unfavorably address” includes: deteriorate, remove, weaken, de- institutionalize, release, reduce, dilute, and the like. Deeper investigations will reveal more mitigating factors that if preserved and/or improved will aid in preventing the recurrence of a problem and/or limiting the severity of its future recurrence. © 2011 W. R. Corcoran, NSRC Corporation,

Fact Nine-Elaboration Allowing any non-robust mitigating factor to go unfortified is to predispose some future event. © 2011 W. R. Corcoran, NSRC Corporation,

Suggestion: Be the “building inspector” for your next root cause analysis. Check the foundation. If it is not sound the structure could collapse. © 2011 W. R. Corcoran, NSRC Corporation,

35 Questions? © 2011, William R. Corcoran, NSRC Corp., ,