ML20198R839

Memorandum Commenting on Definition of Root Cause. Strong Relationship Exists Between Applicant Commitment to Safety & Way Util Commitment Defines Root Cause.Ambiguity in Meaning Desirable.Served on 860609

ML20198R839
Person / Time
Site:	Comanche Peak
Issue date:	06/06/1986
From:	Bloch P Atomic Safety and Licensing Board Panel
To:
References
CON-#286-468 79-430-06-OL, 79-430-6-OL, OL, NUDOCS 8606100233
Download: ML20198R839 (2)

Text

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ha LBP-85 UNITED STATES OF AMERICA sg \ i?g4 NUCLEAR REGULATORY COMMISSION Before Administrative Judges: M Peter B. Bloch, Chairman JUN 919868 Il

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Dr. Kenneth A. McCollom "Q f !

Dr. Walter H. Jordan  ;

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In the Matter of Docket Nos. 50-445-0L

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TEXAS UTILITIES ELECTRIC COMPANY, et al. g (Comanche Peak Steam Electric Station, )

Units 1 and 2) )

) June 6, 1986 MEMORANDUM (Definition of " Root cause")

Having received SSER #13 this morning, the Board wishes to comment on the important issue of how root cause should be defined.

To this point, we have shared Staff's concern about the specificity with which Applicants have defined root cause and we have been waiting to see the task force reports for empirical evidence concerning how Applicants have defined root cause.

We see a strong relationship between Applicants' commitment to safety and the way it defines root cause. A strong commitment to safety will mean that Applicants will see discrepancies, deviations,

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observations and deficiencies as helpful signposts that must be scrutinized in order to find out what is going on in the plant. They will be anxious to understand mistakes so that they can be corrected.

It may be that in some instances, particularly rather unimportant isolated problems, Applicants may define root cause as "the fundamental 8606100233 860606 PDR ADOCK 05000445 G PDR 9 Sob

k)f Root Cause: 2 event or decision that was the most likely cause of the identified problem." SSER #13 at 1-7. However, it may often be the case that there will be more than one root cause. For example, the Staff's definition of root cause would not work for the Three Mile Island Accident or for the recent events at Davis Besse because each of these problems resulted from multiple failures not from one most likely cause.

Nor, obviously, if there has been careless quality assurance accompanied by forgery, would it be adequate to pick "the most likely cause."

The Board considers it to be possible that the ambiguity in the meer,ing of root cause is desirable, just as it has proved impossible to provide more than a vague or intuitive definition for " negligence." We think the spirit of the Staff's comment is entirely consistent with our view of this subject, but we are hopeful that our comments may assist both Applicants and Staff to avoid over-formalizing the definition of root cause and thereby unduly restricting the search for cause that should occur when problems are noted by individuals concerned for safety.

FOR THE ATOMIC SAFETY AND LICENSING BOARD Peter B. Bloch, Chairman ADMINISTRATIVE JUDGE Bethesda, Maryland

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