ML13352A142

South Texas Project, Units 1 and 2 - South Texas Project GSI-191 Licensing Submittal Comparison of Changes Between Rev 1 and Rev 2

ML13352A142
Person / Time
Site:	South Texas
Issue date:	12/16/2013
From:	Singal B K Plant Licensing Branch IV
To:	Koehl D L South Texas
Singal B K
References
Download: ML13352A142 (33)

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South Texas Project GSI-191 Licensing Submittal Comparison of Changes between Rev 1 and Rev 2 Nuclear Regulatory Commission Rockville, MD December 16, 2013

STPNOC Team Participants South Texas Project Mike Murray Steve Blossom Wayne Harrison Ernie Kee ALION Science and Technology Bruce Letellier Dominic Munoz SLIDE 2 Presentation Outline Introduction Meeting objectives and high

-level summary Licensing related changes Revision Timeline Discussion of quantitative changes Discussion of editorial changes Questions and additional discussion SLIDE 3 Desired Outcomes Fully describe changes made to STP GSI

-191 licensing submittal Facilitate NRC understanding of the revision history Discuss selected technical items in detail Explain the rationale for these changes Present requantification impacts of numeric changes Facilitate dialog related to RAI preparation SLIDE 4 Topical Overview SLIDE 5 Requantification Review Process Review Scope CASA Grande Input Disposition

• Focus on changes as central theme

• Spiral down through all topics, increasing detail as needed Change Comparison

High-Level Summary STP GSI-191 licensing submittal revised to address discrepancies between the technical description presented in Vol 3 and quantitative implementation in the CASA Grande calculation Several numeric changes were made that contributed to an increase in from approx 1E-08/yr to approx 3E-08 /yr. These numerical changes made also contributed to an increase in the from approx 9E-12/yr to approx 5E-11/yr. Editorial changes were made to Vol 3, Rev 2 (Nov.) that removed information not utilized directly in the analysis Deletions collapsed document without restructuring Approx 100 pages added to document all CASA Grande input files Approx 20 pages added to explain the changes Related changes were propagated through all enclosures Changes for consistency in Vol. 1, 2 and other enclosures SLIDE 6 Definition of References Technical documents refer to Volumes. The submittal refers to enclosures.

Enclosure 4

-1 is the same as Volume 1 Enclosure 4

-2 is the same as Volume 2 Enclosure 4

-3 is the same as Volume 3 SLIDE 7 SLIDE 8 Licensing Related Changes

NSHC and Enclosure 2 (exemption requests)

No changes made to the No Significant Hazards Considerations (NSHC)

The bases and conclusions for the NSHC are unchanged Enclosure 2, Exemption Requests

- consistency changes for the exemption requests Corrected change in LERF Changed requested review date to June 2015 SLIDE 9

- LAR and associated UFSAR changes Editorial wording changes in the Summary Description with respect to use of the PRA.

Deleted estimated quantification of safety improvement from new strainer design in discussion of new strainers.

Revised references to Enclosure 4-3 (Volume 3) to match revised section numbering in Enclosure 4

-3 (various places).

Deleted paragraph at end of Section 3.3.1 detailing original and numbers since the information is presented in Section 4 of Enclosure 4-2 (Volume 2).

Changed title of Section 3.3.3 to "Description of the PRA" and deleted Sections 3.3.4

- 3.3.6 of the PRA description and referenced the same information presented in Enclosure

4-1 (Volume 1).

SLIDE 10 (cont.)

Deleted debris description details repeated from Enclosure 4-3 (Volume 3) from the operability determination process discussion in Section 4.1.3.

The section appropriately references Enclosure 4-3. Revised UFSAR markups to reflect new revision to Enclosure 4-3. Parameter for Aluminum removed from Table in proposed App. 6A

. Clarified that 10CFR50.59 will be the change control process for the UFSAR sections that implement the proposed license amendment.

SLIDE 11 Revision Timeline SLIDE 12 Timeline January 31, 2013 - STP submitted to the NRC the "STP Pilot Submittal and Request for Exemption for a Risk

-Informed Approach to Resolve Generic Safety Issue (GSI)-191." Included quantitative risk evaluation based on CASA Grande engineering analysis of LOCA spectrum and RiskMan PRA Technical Volumes 1

- 3 plus numerous reports were also finalized to support initial submittal Vol 3 was not transmitted at this time SLIDE 13 Timeline (cont.)

June 19, 2013

- STP revised licensing application to include information judged by the staff to be essential for review prior to acceptance Vol 6.2 was generated and transmitted to provide detailed responses to staff questions Vol 3 was formally transmitted as Rev 1 November 13, 2013

- STP submitted revised licensing application and Rev 2 of Volume 3 Rev 1 of Vol 3 was submitted with the original CASA evaluation (CG

-1) in June of 2013 Rev 2 of Vol 3 was submitted with the revised CASA evaluation (CG

-2) in November of 2013 SLIDE 14 Review Process for Comparison of Vol 3 and CG Review Objectives Align inconsistencies between Vol 3 description and CASA implementation Acknowledge and correct any identified errors Review Process Guidelines Minimize numeric changes in favor of editorial changes Avoid any change not associated with an error or inconsistency No intentional reduction in conservatism No restructure of the risk

-informed closure argument Remove supplementary info not used in the risk calculation Fully document all suspected problems and their disposition Review Findings Category I

- corrections to CASA input or code Category II

- editorial changes to Vol 3 for the purpose of consistency Category III

- no change needed Remove supplementary information SLIDE 15 SLIDE 16 Numeric Changes

Types of Numeric Changes SLIDE 17 *Input file change

• Comment 1.Unqualified coatings failure 1.Potentially nonconservative treatment of UQ failure and fix one transcription error 2.LDFG Debris properties 2.Adopt standard use of microscopic debris properties 3.Definition of Case 9 plant failure state 3.Consistency with PRA failure state definitions 4.Containment spray rates 4.Consistency with failure states as described in Rev 1 *Code level change 5.Total injection flow 5.Transcription error 6.Pipe friction factor 7.Securing one CS pump 6.Misinterpretation of published equation 7.Indeterminat conservatism, EOP consistency

Process for Requantification Run baseline case study each time code or input is modified (one

-at-a-time) and record results Determine the incremental effect of each modification separately Run complete analysis with ALL new modifications implemented simultaneously Determine combined effect of all modifications simultaneously Improved sampling resolution caused greater increase in conditional failure probability than all changes to physical parameters SLIDE 18 Sensitivity Analysis Base Case:

Total Failure Probability = 0.007703 Plant failure Case 01 only Time Step = 10 Minutes Total Run Length = 24 Hours Modifications for Consistency:

Fail Prob % Diff 1.UQ failure rate 0.007702 -0.02% UQ failure fraction 0.008004 +3.91% 2. Debris Properties 0.011770 +52.8% 3. Case 09 redefinition

-- -- 4. Containment Spray Rates 0.007655 -0.62% 5. Total SI Pump Flow Rates 0.007702 -0.02% 6. Pipe friction factor

-- -- 7. Secure one CS pump

-- -- SLIDE 19 CG Requantification 1.Unqualified coatings In Rev. 1, distributions describing unqualified coatings failure fractions were shown. CG

-1 used the mean failure fraction values from these distributions Rev.1 described time

-dependent failure of coatings over 30 days.

CG-1 introduced 9.5% of failed UQ coatings at a uniform rate over 36-hour duration of the calculation New CG-2 runs for Rev. 2 introduced 100

% of failed UQ coatings at a uniform rate over 36

-hour duration of the calculation Rationale:

Uniform time

-dependent failure scheme was potentially non

-conservative Correction to recirculation fraction SLIDE 20 CG Requantification (cont.) SLIDE 21 1.Unqualified coatings (Rev 2, CG

-2) source from upper containment

()= = () =100% = t =6%

CG Requantification (cont.) 2.Debris Properties LDFG surface area to volume ratio In Rev. 1, and CG-1 small and large low density fiberglass (LDFG) were treated as 0.5 and 1-inch cubes respectively for head loss calculations Correct size of 7 microns representing microscopic diameter of LDFG was described in Rev. 2 and implemented in CG 2 Rationale:

Macroscopic treatment of small and large LDFG is nonconservative Adopt standard use of microscopic debris properties SLIDE 22 CG Requantification (cont.) 3.Definition of Case 9 plant failure state Rev. 1 defined Case 9 failure state as 3 HHSI, 1 LHSI, and 3 CS pumps operating CG-1 incorrectly implemented case 9 as 1 HHSI, 3 LHSI, and 3 CS pumps operating Rationale:

Ensure consistency with PRA definition in Volume 2 SLIDE 23 CG Requantification (cont.) 4.Containment spray rates Containment Spray (CS) flow rates CG-1 analysis used one range of flow for all pump failure scenarios CG-2 analysis was changed to match Volume 3 description of flow for plant failure states based on TH calculations of injection flow with multiple pumps No change to Volume 3 content Rationale:

Runout flow is potentially non

-conservative from the perspective of fuel debris accumulation SLIDE 24 Code Level Changes 5.Total Safety Injection Flow TH report provides total injection flow as a function of break size Transcription error of one table value caused slight change in slope of bi-linear fit (Fig. 2.2.2, p 52, Vol 3, Rev 2)

Implemented new slope in existing subroutine 6.Pipe friction factor Formula used for explicit solution of pipe friction factor requires absolute roughness rather than relative roughness Implemented absolute roughness in existing subroutine 7.Secure one CS pump CS-1 secured one CS pump if all ECCS pumps are operable CS-2 secures one CS pump if all CS pumps are operable regardless of other pump failures Consistent with EOPs SLIDE 25 Editorial Changes SLIDE 26 Changes in Rev. 2 All editorial changes in Volume 3 Rev. 2 (Nov.) were performed without re

-ordering the document Content Change Overview Deleted Content Models that were never implemented in CG, but had been summarized in Rev. 1 (June) of Volume 3.

Equations and descriptions whose values were entered into CG as input from engineering calculations, but were not explicitly evaluated by CG analysis.

Inconsistent descriptions of CG implementation Addition of all CG input files to Appendix 1 In Rev. 1 only 1 CG case was shown in Appendix 1 Rev. 2 includes the input files for all five CG cases SLIDE 27 Changes in Rev. 2 (Cont.)

All deleted sections were removed because they were not implemented in the STP analysis. In Rev. 1, these sections were explained, but then described as unused, or supplementary information.

Deleted Sections a)Active water volume (Rev. 1, 2.2.5) b)Initial Pool Chemistry (Rev. 1, 2.2.18) c)Pool pH (Rev. 1, 2.2.19) d)Metal Quantity (Rev.1. 2.2.20) e)Distribute Total LOCA Frequency to Weld Location (Rev. 1, 5.3.5) f)Chemical Concentration Model (Rev. 1, 5.5.1) g)Solubility Limit (Rev. 1, 5.5.2) h)Chemical Product Type, Form, and Quantity (Pool and Core)

(Rev. 1, 5.5.3) SLIDE 28 Changes in Rev. 2 (Cont.)

Inconsistent description of CG implementation Weld Break Frequency Rev. 1 described the relative frequency vs. break tables (2.2.3

-2.2.10) as being linearly interpolated to find 0.1 inch increments in break size for each weld category CG filtered out log

-log interpolated values between break sizes before linearly interpolating to find break frequency. Updated explanation provided in Rev. 2.

Qualified Coatings Rev.1 described break

-size dependent qualified coatings quantities.

Rev. 2 was updated to reflect that bounding maximum qualified coatings quantities are used in CG analysis SLIDE 29 Changes in Rev. 2 (Cont.)

Inconsistent description of CG implementation Clean strainer head loss In Rev. 1, a velocity

-dependent clean strainer head loss was described Rev. 2 was updated to state that the maximum clean strainer head loss was implemented in CG Gas void fraction at strainer Described as being split between pumps in Rev.1.

In CG the total void fraction calculated at the sump was assumed at each pump; this was updated in Rev. 2.

SLIDE 30 Changes in Rev. 2 (Cont.)

Inconsistent description of CG implementation Chemical bump up factor Rev. 1 states that the end points of the chemical bump up distribution were included in the statistical sample design Rev. 2 updated to explain that CG did not enforce sampling of the end points Fiberglass Erosion Rev. 1 discussed timing associated with fiberglass erosion (5.5.6).

Only the erosion transport fractions were used in CG and discussed in Rev. 2 analysis.

SLIDE 31 Changes in Rev. 2 (Cont.)

Inconsistent description of CG implementation Debris transport logic trees Example debris transport logic trees displayed in Rev. 1.

Rev. 2 was updated to show all logic tree inputs that were used in CG. Composite debris constituent surface to volume ratio Rev. 1 described conventional method for calculating surface to volume ratio for multiple constituents. (Equation 50)

The linear mass weighting scheme was implemented in CG and is described in Rev. 2. (Equation 39)

SLIDE 32 SLIDE 33 Questions and additional discussion