ML17285A005

10/11/2017 NEI 96-07, App D Meeting NEI Backup Slides

ML17285A005
Person / Time
Site:	Nuclear Energy Institute
Issue date:	10/11/2017
From:	Leblond P Nuclear Energy Institute
To:	Office of Nuclear Reactor Regulation
Holonich J
References
Download: ML17285A005 (10)

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BACK-UP BIN SLIDES Peter LeBlondNEI 96-07 Appendix D Team

Nuclear Energy InstituteOctober 11, 2017 A n informal "Binning System" will be introduced to assist in organizing the most common digital-related permutations

• Slide 20 is generalized to describe this approach

• Following this generalization, we can describe four commonly encountered situations.

o Each of these "Bins" will have a nominally

expected outcomeStandardized Approach Can Be Graphically Expressed Identify the DBF(s) involved and classify its relationship with the identified functions below using NEI 96-07, definition 3.3.(If no DBF apparently exists, specialized evaluations may be required.)

GraphicalSummary of Approach*Describe the activity*Identify any functions involvedIdentify all Safety Analyses that credit directly or indirectly the DBF identified below.(If no Safety Analysis apparently exists, specialized evaluations may

be required.)*Is the DBF preserved?*Was a FMEA needed to assess

the propagation of effects? *Do all assumptions remain valid?*Does the Safety Analysis remain

valid?*Determine if SCCF:Is classed as "create a possibility."

Induces effects across trains FMEA is needed?

Slide 20

• Inspection of the graphic on the previous slide results in the recognition that repetitive Evaluation

patterns are likely oIn every instance, an individual assessment must be made*Four expected patterns, or "Bins" will be described Repetitive Patterns of Evaluation Repetitive Patterns of Evaluation Four Bins Bin #1*Non-Safety Related*Safety Related w/o Single Failure Criteria (SFC)

Requirement Bin #2

• Safety Related w/

SFC req.oNOT immediately required o NO short-term auto

actions Bin #3

• Safety Related w/

SFC req.o SCCF likelihood sufficiently

low Bin #4

• Safety Related w/

SFC req.o SCCF likelihood NOT sufficiently

low

• Description -Involves functions that are either:

o Non-Safety Related oSafety-Related but not associated with any single failure criteria

• Discussion Points:

oTypically would be incapable of having a different result (Criterion 2 would control.)

oSafety Analyses already assume mis-behaviourof

NSR SSCs oCare must be taken to ensure all Safety Analyses remain valid (e.g., functions combined, etc.)

• Examples: oTurbine or FW controls o AFW turbine controls oMCR Chillers with no rack cooling functions Repetitive Patterns of EvaluationCont. -"Bin #1"

• Description -Involves Safety-Related functions required to comply with single failure criteria that:

oAre not immediately required to respond to an event oTypically are not associated with very short-term

automatic actions

• Discussion Points:

oA new FMEA would likely be required oCompliance with current procedures results in detection and a restorative response

• Examples: oDigital EDG jacket water surge tank controls oMCR Chillers with rack cooling functions o Radiation Monitors that actuate CREFS Repetitive Patterns of EvaluationCont. -"Bin #2"

• Description -Involves Safety-Related functions required to comply with single failure criteria and an engineering evaluation determined the likelihood of SCCF is "sufficiently

low": oMay immediately respond to an event oCan be associated with very short-term automatic action

• Discussion Points:

oDoes not "create a possibility" of a SCCF oRelies on results from engineering evaluations

• Examples: oEDG voltage regulator digital upgrade with no analog back-up oReplacement of transmitters with digital devices that control safeguard actuation Repetitive Patterns of EvaluationCont. -"Bin #3"

• Description -Involves Safety-Related functions required to comply with single failure criteria and an engineering evaluation determined the likelihood of

SCCF is not "sufficiently low"

oMay immediately respond to an event (typical) oCan be associated with a very short-term automatic action oSystem application is complex

• Discussion Points:

oDoes "create a possibility" of a SCCF oNo potential for FMEA application o LAR required

• Examples: oReactor Protection System upgrade Repetitive Patterns of EvaluationCont. -"Bin #4"