ML14237A002

ISA 67 04 and Rg 1.105, Rev. 4 Consolidated Comments rev5

ML14237A002
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Issue date:	08/14/2014
From:	Office of Nuclear Regulatory Research
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References
DG-1141 RG-1.105, Rev. 4
Download: ML14237A002 (10)

Text

ISA 67.04 Committee Input on Proposed Revision 4 of RG 1.105 NRC Public Meeting Draft Regulatory Guide DG-1141 (proposed RG 1.105 rev 4) 8/14/2014

Key Areas of Concern

• Scope Expansion beyond Safety Related

• Lack of Endorsement of ISA 67.04

• Significant expansion of cost to industry without increase in nuclear safety

• Creates new definitions and processes

• Introduces Regulatory uncertainty

• Technical inconsistencies/disagreements with current industry practice 8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 2

Scope Expansion

• New RG 1.105 scope expands beyond LSSS functions; includes other TS items (e.g. those identified in PRA, Non Safety Related, etc.) & inconsistent with RG Title.

• The RIS 2006-17 applied to a subset of Tech Spec instruments. Is it being expanded by the RG to all Safety and Non Safety Tech Spec instruments?

• EOP calculations should be best estimate not 95/95.

• Setpoint calc scope increased to include Safety Analysis scope, e.g. upstream & downstream response time.

Current industry practice includes dynamic response within the safety analysis.

8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 3

Lack of Endorsement of ISA 67.04

• Rev 4 doesnt explicitly endorse ISA 67.04 part 1.

• The draft RG is significantly expanded from 9 pages to 33 pages appears to replace the industry consensus standard.

• The draft RG does not exercise the process of industry developing best practice standards for nuclear safety.

• RG should endorse or reference parts of ISA 67.04 where needed, e.g. Part 2 M&TE & Digital uncertainties.

8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 4

Expansion of costs with no increase in Safety

• The proposed documentation requirements (ie., 95/95, histograms, etc.) for every uncertainty parameter will result in significant cost increases with no increase in safety. Use of NRC guidance from NUREG CR-3659 for vendor stated specifications (i.e., Reference accuracy) would significantly reduce these increases. This reasonable guidance provides conservative calculation results as validated by evaluation of calibration history results.

• Proposed RG 1.105 requirements will reduce the already limited number of vendors due to the increased requirements for data.

• Todays methods used by utilities result in conservative calculations for documenting that the LSSS protects the Analytical Limit.

• Small changes to RG 1.105 are warranted, not a significant overhaul.

8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 5

New Definitions and Processes

• New and altered terminology introduced vs. invoking ISA 67.04 industry terminology.

• Transition path to new R4 terminology not defined, will result in confusion so ISA terminology should be used.

• The draft proposes that calculations are to be maintained with plant implementation procedures such as calibration instructions. Actually, consistent with 10CFR50 Appendix B III and XI, the Engineering setpoint calculation program is one of the measures that drives plant specific configuration control processes, not vice versa. The RG should not be dictating specific plant methods of plant configuration control. INPOs Setpoint Control Good Practice, EPG-01, is the preferred guidance for licensees.

8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 6

Regulatory Uncertainty

• This appears to be a backfit to our plants current licensing basis and documented design basis.

• This will increase the number of cases where applicants invoke compliance with RG is not required.

• Future LAR submittals will require changes to the plants current documented licensing basis as reflected in our SARs.

• What will NRC site inspections use for evaluation criteria?

• Draft RG is inconsistent with plants that have TSTF 425 programs.

• As Found (AFT) and As Left (ALT) tolerances are proposed operability criteria instead of existing Allowable Values which are in most plants Tech Specs. This goes well beyond RIS 2006-17 and the approved TSTF-493, R4 process.

8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 7

Technical Issues

• Safety Limit requirements proposed to apply to Analytical Limits (AL).

• Changing probability of trip at or before AL from 95% (Rev 3) to 97.5%

(Draft Rev 4).

• Precedent of 95% probability from Licensed Safety Analysis. Basis for change to 97.5% probability not provided.

• Should utilize previous history and industry input on 95/95.

• RG should point to NUREG-1465 pg 179, or a Statistics Textbook for technical basis.

• Requires the drift error to be extrapolated linearly. Other methods that are technically supported should be allowed. This prescribed method also conflicts with the move towards performance based operability by introducing very conservative drift allowances into the As Found tolerance.

• Calibration history excluded from use for drift analysis. Inconsistent with GL 91-04.

• Stated SRSS criterion deleted random.

8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 8

Technical Issues (cont.)

• Use of bounding values vs. exact 95% confidence value for device performance data relating to post accident or seismic conditions is good, but it is but not clear what the NRC staff expects.

• How to Independence to be demonstrated?

Normally the calculation preparer identifies and evaluates known dependence but does not perform a formal analysis to demonstrate all SRSS parameters are independent.

• Additional technical issues were noted but not listed here.

8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 9

Going Forward

• Industry would like to work to address these concerns by:

- Active Engagement with the staff on these concerns.

- Reduction in the volume of the draft RG by:

• Providing revisions to ISA 67.04 to address some of these issues based upon consensus agreement.

• NRC to references specific sections of ISA 67.04 part 2 sections.

- Address Allowable Value and required criteria for performance monitoring methods.

8/14/2014 Draft B ISA 67.04 Committee Input on Draft RG1.105 10