ML17285A005

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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Peter LeBlond NEI 96-07 Appendix D Team BACK-UP Nuclear Energy Institute BIN SLIDES October 11, 2017

An informal Binning System will be introduced to assist in organizing the most common digital-related permutations

Standardized Approach Can Be Graphically Expressed

• 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 outcome

Graphical Summary of Approach Identify all Safety Analyses that credit directly or indirectly the DBF identified

• Do all assumptions below. remain valid?

(If no Safety Analysis apparently

• Does the Safety exists, specialized evaluations may Analysis remain be required.) valid?

• Is the DBF Identify the DBF(s) involved and classify its preserved?

relationship with the identified functions

• Was a FMEA below using NEI 96-07, definition 3.3. needed to assess (If no DBF apparently exists, specialized the propagation evaluations may be required.) of effects?

• Determine if SCCF:

• Describe the activity Is classed as create a

• Identify any possibility.

functions involved Induces effects across trains FMEA is needed? Slide 20

Repetitive Patterns of Evaluation

• Inspection of the graphic on the previous slide results in the recognition that repetitive Evaluation patterns are likely o In every instance, an individual assessment must be made

• Four expected patterns, or Bins will be described

Repetitive Patterns of Evaluation Four Bins Bin #1 Bin #2 Bin #3 Bin #4

• Non-Safety

• Safety

• Safety

• Safety Related Related w/ Related w/ Related w/

• Safety SFC req. SFC req. SFC req.

Related w/o o NOT o SCCF o SCCF Single Failure immediately likelihood likelihood Criteria (SFC) required sufficiently NOT Requirement o NO short- low sufficiently term auto low actions

Repetitive Patterns of Evaluation Cont. - Bin #1

• Description - Involves functions that are either:

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

• Discussion Points:

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

o Safety Analyses already assume mis-behaviour of NSR SSCs o Care must be taken to ensure all Safety Analyses remain valid (e.g., functions combined, etc.)

• Examples:

o Turbine or FW controls o AFW turbine controls o MCR Chillers with no rack cooling functions

Repetitive Patterns of Evaluation Cont. - Bin #2

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

o Are not immediately required to respond to an event o Typically are not associated with very short-term automatic actions

• Discussion Points:

o A new FMEA would likely be required o Compliance with current procedures results in detection and a restorative response

• Examples:

o Digital EDG jacket water surge tank controls o MCR Chillers with rack cooling functions o Radiation Monitors that actuate CREFS

Repetitive Patterns of Evaluation Cont. - Bin #3

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

o May immediately respond to an event o Can be associated with very short-term automatic action

• Discussion Points:

o Does not create a possibility of a SCCF o Relies on results from engineering evaluations

• Examples:

o EDG voltage regulator digital upgrade with no analog back-up o Replacement of transmitters with digital devices that control safeguard actuation

Repetitive Patterns of Evaluation Cont. - Bin #4

• 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:

o May immediately respond to an event (typical) o Can be associated with a very short-term automatic action o System application is complex

• Discussion Points:

o Does create a possibility of a SCCF o No potential for FMEA application o LAR required

• Examples:

o Reactor Protection System upgrade