NOC-AE-15003220, Description of Revised Risk-Informed Methodology and Responses to Round 2 Requests for Additional Information Regarding STP Risk-Informed GSI-191 Licensing Application

Description of Revised Risk-Informed Methodology and Responses to Round 2 Requests for Additional Information Regarding STP Risk-Informed GSI-191 Licensing Application

ML15091A440
Person / Time
Site:	South Texas
Issue date:	03/25/2015
From:	Gerry Powell South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-15003220, STI 34054100, TAC MF2400, TAC MF2401, TAC MF2402, TAC MF2403, TAC MF2404, TAC MF2405, TAC MF2406, TAC MF2407, TAC MF2408, TAC MF2409
Download: ML15091A440 (244)

Text

Nuclear Operating Company Soulh Teas ýPý xtrirk ew*'iaqgStalion PO &*a28,9 ftdsurtbh. Teas 7748J March 25, 2015 NOC-AE-15003220 10 CFR 50.12 10 CFR 50.90 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Description of Revised Risk-Informed Methodology and Responses to Round 2 Requests for Additional Information Regarding STP Risk-Informed GSI-191 Licensing Application (TAC NOs MF2400 through 2409)

References:

1. Letter, G. T. Powell, STPNOC, to NRC Document Control Desk, "Supplement 1 to Revised STP Pilot Submittal and Requests for Exemptions and License Amendment for Risk-Informed Approach to Resolving Generic Safety Issue (GSI)-191, " November 13, 2013, NOC-AE-13003043, ML13323A183

2. Letter, Lisa Regner, NRC, to Dennis Koehl, STPNOC, "South Texas Project, Units I and 2- Request for Additional Information Related to Request for Exemptions and License Amendment for Use of a Risk-Informed Approach to Resolve the Issue of Potential Impact of Debris Blockage on Emergency Recirculation During Design-Basis Accidents at Pressurized-Water Reactors", (TAC Nos. MF2400 Through MF2409), March 3, 2015, ML14357A171 This submittal provides a description to a revision to the risk-informed methodology used in the Reference 1 licensing application. Italso responds to the requests for additional information (RAI) provided in Reference 2 with regard to the STP Nuclear Operating Company (STPNOC) risk-informed application to address GSI-191 (Reference 1). The responses provided are listed in the Attachments. Responses to the SNPB Round 2 RAIs, APLAB Key Assumptions/Key Sources of Uncertainty RAI-lc, and SSIB RAI-66 are not yet complete and will be provided in a later submittal. The response to SCVB RAI-1 7 with respect to Containment Design is not yet completed and will be provided in a later submittal. is provided for the staffs review and describes a revision to the risk-informed evaluation methodology used in the STPNOC pilot application. The "Risk over Deterministic" or RoverD method is a less complex analysis that has a deterministic element that uses STP plant-specific testing to demonstrate that the STP design satisfactorily mitigates the effects of debris from most postulated LOCAs. The risk-informed element then applies NUREG 1829 in comparison to the STP PRA to demonstrate that the risk from debris generated by LOCAs that are not bounded by the testing is very small, in accordance with RG 1.174. Also in accordance with RG 1.174, there is sufficient safety margin and defense in depth to assure that the fundamental safety principles on which the plant design was based are not compromised by the proposed change. Exemptions to the regulations described in Reference 1 will only need to apply for the risk-informed portion of the RoverD methodology. STPNOC will submit a supplement to the pilot licensing application that incorporates RoverD. The key elements of RoverD were STI 34054100 A00W

NOC-AE-15003220 Page 2 of 3 presented to the NRC staff in a public meeting on February 4, 2015. Based on the use of the RoverD methodology, the testing described in STPNOC's letter dated October 30, 2014 (ML14344A545) will not be required.

This correspondence contains one regulatory commitment listed in Attachment 8.

If there are any questions, please contact Mr. Wayne Harrison at 361-972-8774.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on: -Mark , ,

G. T. Powell Site Vice President awh Attachments:

1. Response to APLAB Request for Additional Information

2. Response to EMCB Request for Additional Information

3. Response to ESGB Request for Additional Information

4. Response to SCVB Request for Additional Information

5. Response to SSIB Request for Additional Information

6. Response to STSB Request for Additional Information

7. Description of the Risk over Deterministic (RoverD) Methodology

8. Regulatory Commitments

9. Definitions and Acronyms

NOC-AE-15003220 Page 3 of 3 cc:

(paper copy) (electronic copy)

Regional Administrator, Region IV Morgan, Lewis & Bockius LLP U. S. Nuclear Regulatory Commission Steven P. Frantz, Esquire 1600 East Lamar Boulevard Arlington, TX 76011-4511 U. S. Nuclear Regulatory Commission Lisa M. Regner Lisa M. Regner Michael Markley Senior Project Manager John Stang U.S. Nuclear Regulatory Commission One White Flint North (08H04) NRG South Texas LP 11555 Rockville Pike John Ragan Rockville, MD 20852 Chris O'Hara Jim von Suskil NRC Resident Inspector U. S. Nuclear Regulatory Commission CPS Energy P. O. Box 289, Mail Code: MN116 Kevin Polio Wadsworth, TX 77483 Cris Eugster L. D. Blaylock Crain Caton & James, P.C.

Peter Nemeth City of Austin Cheryl Mele John Wester Texas Dept of State Health Services Richard A. Ratliff Robert Free

NOC-AE-1 5003220 Attachment 1 Attachment I Response to APLAB Request for Additional Information

NOC-AE-15003220 Attachment 1 Page 1 of 16 Probabilistic Risk Assessment (PRA) Licensing Branch (APLA)

NOTE: The numbering system has been retained from the first set of RA/s issued by letter dated April 15, 2014, for consistency. Additional RA/s have been assigned new numbers.

Project Quality Assurance Regulatory Guide (RG) 1.174, Revision 2, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant Specific Changes to the Licensing Basis,"

May 2011 (ADAMS Accession No. ML100910006), Section 5, "Quality Assurance," provides the NRC staffs position on quality assurance (QA) requirements for risk-informed changes to the licensing basis. Specifically, this section contains several provisions that should be met when a licensee elects to use PRA information to enhance or modify activities affecting the safety-related functions of structures, systems, and components (SSCs). When referring to QA, the term "activities" is typically interpreted to mean designing, purchasing, fabricating, handling, shipping, storing, cleaning, erecting, installing, inspecting, testing, operating, maintaining, repairing, refueling, and modifying. Therefore, the proposed decision not to remove problematic insulation represents a modification to several activities affecting the safety-related functions of SSCs, namely the Emergency Core Cooling System (ECCS) and Containment Spray (CS) systems.

1. Please describe how "PRA information" that is used to justify not removing problematic insulation including but not limited to the PRA, CASA Grande, and supporting analyses meets the following provisions in RG 1.174, Section 5:

• Use personnel qualified for the analysis.

Use procedures that ensure control of documentation, including revisions, and provide for independent review, verification, or checking of calculations and information used in the analyses.

Provide(s) documentation and maintain(s) records in accordance with the guidelines Section 6 of RG 1.174.

Use(s) procedures that ensure that appropriate attention and corrective actions are taken if assumptions, analyses, or information used in previous decisionmaking are changed (e.g., licensee voluntary action) or determined to be in error.

Response

The LAR risk assessment is based on the STPNOC procedure OPGP05-ZE-0001 "PRA Analyses/Assessments" under the STP Operations Quality Assurance Program (OQAP). The procedure steps were completed by ABS Consulting personnel and STPNOC PRA Qualified Analysts. ABS Consulting personnel are qualified to the STPNOC procedure. All supporting analyses and calculations were performed within the GSI-191 QA process as summarized in the LAR Enclosure 4-1, page xx, Figure 4, "Illustration of the

NOC-AE-1 5003220 Attachment 1 Page 2 of 16 major elements of the STP quality assurance plan for risk-informed closure of GSI-191."

In addition, the analyses, calculation, and methodologies used were reviewed by an independent oversight group, University of Illinois at Urbana-Champaign.

STP's station corrective action program ensures that appropriate attention and corrective actions are taken if assumptions, analyses, or information used in previous decisionmaking are changed (e.g., licensee voluntary action) or determined to be in error.

2. The LAR, Volume 1 describes some quality assurance activities that were implemented in support of the LAR but states that CASA Grande "is a proprietary MATLAB application, which was unavailable to the [quality] oversight team." Therefore, please provide a brief summary of the software QA (SQA) program for CASA Grande and the anticipated date when the CASA Grande software will become compliant with that SQA program. Describe any standards and upon which the SQA is based.

Response

Alion Science and Technology (Alion) is performing the Software Validation and Verification under the auspices of Alion's Quality Assurance Manual and Quality Assurance Procedures referred to as Alion's QA Program. The QA Program complies with 10 CFR 50 Appendix B and NQA-1 requirements and has been audited and approved by numerous utilities, NUPIC and NIAC.

STPNOC has provided Alion with OPGP07-ZA-0014, Revision 9, "Software Quality Assurance Program". The requirements of OPGP07-ZA-0014 and Alion's compliance are provided in Table 1. Per OPGP07-ZA-0014, CASA Grande is classified as Level 3 Software. The requirements for Level 3 are provided below in Table 10.1, excerpt from OPGP07-ZA-0014, Revision 9.

Table I - OPGP07-ZA-0014 requirement, Alion's compliance STP ALION Requirements Software Requirements Specification Design Software Design Specification/Theory Manual User's Manual User's Manual Test Protocol Software Adequacy Nalidation Plan Test Plan Validation Plan Installation Instructions (UM) Installation Instructions/ User's Manual

NOC-AE-1 5003220 Attachment 1 Page 3 of 16 Table 2 - Table 10.1 excerpt from OPGP07-ZA-0014, Revision 9)

Level I Level 2 Level 3 Level 4 Level Requirement Document X X X X Design Document X X X Test Plan Document X X X Test Case Document X X X X Test Report * * *

• User Instruction/Manual Retirement Plan 00 411 Document

• Required if there are 5 or more Test Cases

• Sponsor determines the need for a User Instruction/Manual 0 Required only when the software or data is removed from access by users At present time Alion has modified CASA Grande and Version 1.7 will be the Verified and Validated version Alion will issue to STP in addition to the aforementioned required documents. The anticipated date of issue is April 2, 2015.

3. Identify any QA programs that were employed for any traditional engineering analyses/calculations performed in support of the LAR and state whether these programs meet 10 CFR 50, Appendix B requirements.

Response

The PRA analysis is not required to meet Appendix B requirements. The PRA analysis is under the STP OQAP. Vendors were contracted to work to a common engineering standard that required a preparer, reviewer, and approval. Independent oversight was also part of the process. As shown in the flow chart in Enclosure 4-1, page xx, vendor-supplied documents and calculations are processed through STPNOC Engineering Procedure OPGP04-ZA-0328. RoverD utilizes deterministic analyses previously performed in support of the December 2008 submittal in response to GL 2004-02. These were performed in accordance with Appendix B requirements. These requirements were invoked by the contracts STPNOC had with Westinghouse and with Performance Contracting Inc. (PCI). The sub-contractors included Alion; Enercon; Areva; and Automated Engineering services (AES). Work by these sub-contractors was also to App. B requirements.

In addition, the sump design and construction was performed in accordance with App. B requirements.

NOC-AE-15003220 Attachment 1 Page 4 of 16

4. Describe the QA program employed by each vendor or contractor that performed calculations or analyses used to support the LAR. Explain whether vendor QA programs were assessed by STPNOC for compliance with applicable QA requirements.

Response

As shown in the flow chart in Enclosure 4-1, page xx, vendor documents are processed through STPNOC Engineering Procedure OPGP04-ZA-0328.

Introduction The STP risk-informed GSI-191 pilot project quality assurance process is illustrated in Figure 1 below. As shown in the figure, project contractors developing inputs to the PRA are required to have a local quality assurance program. In general, the quality assurance processes the vendors adopted are unique to the project but nevertheless incorporate standard and generally accepted quality assurance practices. Each vendor's program is described in more detail in following sections.

The vendor personnel assigned to the project and responsible for product quality at the vendor location are qualified to do work on the specific (risk-informed pilot) project per the STPNOC plant procedure OPGP03-ZT-0138. In addition, the project uses independent technical oversight review for critical peer review on the work performed.

A qualified STPNOC PRA analyst is ultimately responsible for ensuring the PRA inputs are reasonable for use in the PRA. Personnel qualified to the STP analysis/assessment procedure to perform PRA calculations per the STP engineering qualification program use the PRA inputs. The overall programmatic requirements for PRA projects are captured in OPGP04-ZA-0604, "Probabilistic Risk Assessment Program".

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NOC-AE-15003220 Attachment 1 Page 6 of 16 ABS Consulting[ProbabilisticRisk Assessment]

Quality Program Aspects:

ABS consulting personnel working on the project are qualified to perform the STPNOC plant procedure OPGP05-ZE-0001, "PRA Analyses/Assessments".

OPGP05-ZE-0001 is used for all STP PRA assessments, calculations, and applications when data are being developed or analyses are required.

Each analysis performed in OPGP05-ZE-0001 is assigned a unique ID and revision number. The ID for the risk-informed GSI-191 pilot license submittal is PRA-13-001, Revision 0. Analyses and assessments may be revised as necessary to reflect new information or changed requirements.

Texas A&M [Thermal-Hydraulics]

Quality Program Aspects:

The thermal-hydraulics models are new work for STP. That is, the risk-informed pilot project did not adopt existing models of containment, RCS, and ECCS due to limitations in the modeling software, nodalization, and application model limitations.

The TAMU quality plan follows standard engineering practice requiring one qualified individual to develop an analysis and a second, independent reviewer to validate the work. In addition, thermal-hydraulics practice includes verification of the inputs for the simulation by comparison against (expected) steady-state (time-invariant boundary conditions) and transients. Because the simulation is for an operating plant, the steady-state operating point is obtained from plant measurements. In addition, unmeasured state points are confirmed against other engineering analyses and design values. Existing simulations (MAAP, RETRAN, licensing applications) are used for further support.

The transient verification follows steady-state verification and since, in general, no data exist for many of the transients simulated, the simulation is verified against other accepted transient analyses such as the plant simulator, UFSAR Chapter 15 analyses, and "generic" analyses in the open literature. The results of the thermal-hydraulic model verifications are captured in documents specific to the verification.

For each specific transient case calculated for use in the engineering analyses, the generally accepted engineering practice of preparer and reviewer was followed.

Each individual transient analysis is documented in a report that is identified with the preparer and reviewer. The scope of review includes not only appropriate input data but reasonableness of the results as well. Any results that appeared inconsistent with intuition were studied and explained.

Alion Science and Technology [EngineeringAnalysis & Quantification(CASA Grande)]

Quality Program Aspects:

NOC-AE-1 5003220 Attachment 1 Page 7 of 16 At the time Figure 1 was developed responsibility for engineering analysis and quantification was with LANL. Subsequently, these responsibilities were transferred to Alion Science. The risk-informed pilot project scope of work was deemed non-safety and therefore not performed under Alion's 10 CFR 50 Appendix B, 10 CFR Part 21 and ASME NQA-1 -1994 Quality Assurance Program; however, for Alion's development and review of calculations for the non-safety project, best engineering practices were followed. The initial stage of the non-safety project regarding CASA Grande was to develop the calculational tool, verify the accuracy of the tool, begin software development to develop the code, run a test case and perform a comparison. Test cases with confirmation using hand calculations were used to verify that the CASA Grande calculational methods were accurate and proper. The current SQA is described in the response to RAI 2 above.

UT Austin [Uncertainty Quantification]

Quality Program Aspects:

UT uses standard quality control aspects for analyses, documents, and technical reports. This consists primarily of a preparer, a reviewer, and an approver (either internal to UT or external).

University of New Mexico [Chemical Effects]

Quality Program Aspects:

All chemical effects experiments work is performed using the UNM quality assurance program manual, "CorrosionlHead Loss Experiments (CHLE) Project Quality Assurance Program Manual Revision 2", June 18, 2012. Standard laboratory practice was followed for keeping laboratory notes and observations.

UNM has been performing the Corrosion Head Loss Experimental (CHLE) Program under the quality assurance program that was developed for this project. As part of this program, all calculations for conducting a test are performed by one person and checked by a different individual. Metal ion concentrations have been analyzed by a commercial lab and instruments such as pH meters and balances have been calibrated with appropriate standards. Written procedures were prepared and followed for each tank test. After each experiment was conducted, a report was written. That report was checked by a separate individual at UNM and was then checked by an individual at STP and another individual at Soteria/UlUC Consultants. Based on the procedure we have followed for report writing and checking, we are not aware of any inaccuracies between the tests that were actually done and the results that are reported in the corresponding reports.

University of Illinois at Urbana-Champaign[Technical Oversight]

A team from the University of Illinois at Urbana-Champaign (UIUC) has been providing Independent Technical Oversight of the STPNOC Risk-Informed GSI-191 project. Two key members of this team were affiliated with Soteria Consultants (Soteria) in 2012; therefore, the Oversight function was carried out under Soteria that year. In January 2013, the two key members joined the faculty of the Nuclear

NOC-AE-15003220 Attachment 1 Page 8 of 16 Engineering Department at UIUC and, from that time, the Independent Oversight of the STP project was performed under a contract between STPNOC and UIUC.

STPNOC commissioned the Independent Oversight team to help ensure the quality and validity of the research and development undertaken. The main objective of Independent Technical Oversight has been to perform an independent and in-depth scientific review of the phenomenological models and experiments developed and conducted for the Risk- Informed GSI-191 project. The Oversight team's scope of work covered the critical review of all the documents related to the technical areas of the project such as location-specific Loss-of-Coolant-Accident (LOCA) frequency modeling, Jet formation physics, Debris generation, Debris transport, Strainer conventional head loss, Penetration, Reactor thermo-hydraulic, Boron precipitation, Uncertainty quantification, Chemical effects, Coating, and Probabilistic Risk Analysis. The scope of the Oversight did not include the review of the CASA Grande software development, run, or process.

The Independent Oversight Team is specifically qualified to peer review the methodologies, experiments and calculations of the STP project. The Oversight team members have academic (holding Ph.D.'s) and industry experience in both probabilistic and deterministic domains, and are capable of (1) understanding probabilistic methods (e.g., PRA and uncertainty analysis), (2) analyzing physical and chemical phenomena (e.g., containment corrosion tests, strainer performance tests, and chemical effects tests, thermo-hydraulic modeling) (3) providing scientific and practical feedback, and (4) producing technically-sound and clear peer review documentation.

The Independent Oversight team provided the analysis team (all other vendors) with written comments and all of these comments were formally resolved. The comments and resolutions are documented and available. Each set of comments was developed by one or two oversight team members and reviewed by the third member of the team before its submittal to STPNOC and the related analysis vendor.

Soteria/UlUC's approach included both "active" and "passive" oversight. Two Ph.D.'s of Soteria/UlUC interacted and collaborated with the analysis teams to provide feedback and to offer active oversight services. Because of the multidisciplinary and integrative nature of the project, members of the oversight group were required to participate in meetings and then follow up on the discussions and issues with the other group members involved in the STP project.

Specific areas of concern and review were also discussed with Soteria/UIUC's passive oversight members (both senior and junior experts in the related fields).

The Soteria/UlUC team was involved in both "informal" and "formal" oversight activities for the STPNOC Risk-Informed project. Examples of informal activities were (1) reviewing pre-meeting technical reports and documents related to NRC public meetings and providing comments, (2) providing technical support in developing ACRS presentations, and (3) participating in brainstorming sessions on diverse technical topical areas with the required follow-up on the proposed ideas.

Some of the formal oversight activities included (1) participating in weekly technical team teleconferences and providing feedback, (2) participating in monthly technical meetings and providing comments, and (3) reviewing reports and documents and developing written comments and follow-up resolutions.

NOC-AE-15003220 Attachment 1 Page 9 of 16 In conclusion, the independent oversight has performed concurrent peer reviews of documents, communicated review comments, has followed up with review comment resolutions, and has analyzed industry limitations and regulatory concerns to temper comments. That is, the oversight team has provided reasonable comments directed towards ensuring academically defensible work results, but recognizes that the project will generally adopt existing technologies (albeit in new ways). Based on the Soteria/UlUC team's review, the STPNOC Risk-Informed project is an outstanding blend of advanced and conventional methods that not only contributes towards the closure of the GSI-191 issues, but also makes a significant contribution to the formal incorporation of underlying physical failure mechanisms of certain post-LOCA events into Probabilistic Risk Assessment (PRA).

Soteria/UIUC oversight activities confidently concluded that the STPNOC Risk-Informed project, having a well-designed combination of probabilistic and deterministic methodologies, has made important contributions to the closure of GSI-191 issues. The Soteria/UlUC team is confident in the scientific validity of methodologies, experiments, and calculations. The oversight team could not arrive at the same conclusion regarding the CASA Grande code because the review of the CASA Grande software development, run, and process were not included in the scope of the work specified for the oversight team.

Treatment of Unanalyzed Plant Conditions

1. RG 1.200, Revision 2, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," Revision 2 (ADAMS Accession No. ML090410014), Section 1.4, "PRA Development, Maintenance, and Upgrade," states that plant information used in the Probabilistic Risk Assessment (PRA)

(e.g., expected thermal-hydraulic plant response to different states of equipment) should be as realistic as possible. Verify that the conditional split fraction values (i.e., failure probabilities used by PRA) for sump failure and in-vessel failure are based on CASA Grande simulations that represent accurately plant conditions for each accident sequence relevant to the LAR, or justify that the chosen failure probabilities are upper bounds for any plant conditions that might occur for a given scenario. For example, for plant conditions where a simulation is impractical, unnecessary, or not performed for any other reason, a split fraction value of 1.0 should be assigned or a qualitative argument should be made to select an existing CASA Grande result as bounding. Based on information provided in the LAR Volumes 2 and 3, this approach is already employed for pump states. Each of the 64 pump states identified in the LAR were assigned conditional split fraction values for sump and in-vessel failure that were based on:

• CASA Grande simulations (pump states 1, 22, 9, 26, 43)

• Qualitative arguments as to why existing CASA Grande results are bounding (the 11 bounded states)

• Assigned a conditional core damage probability of 1.0 (48 other pump states)

A similar verification that assigned failure probabilities are realistic or bounding should be applied to all other unanalyzed plant conditions including but not limited to:

0 Number of containment fan coolers not equal to 6

NOC-AE-15003220 Attachment 1 Page 10 of 16

• Failure of containment isolation

• Failure of operators to secure one train of CS early

• Failure of operators to secure remaining trains of CS late

• Failure to switch to hot leg injection prior to securing CS trains

• Failure to swap to hot leg (HL) recirculation

• Failure of a running pump following a successful start

• Failure of one or more residual heat removal system heat exchangers Therefore, provide the results of a systematic review of all accident sequences containing a top event corresponding to one of the seven GSI-191 failure modes. For each sequence, provide one of the following:

a. Confirmation that the split fractions assigned to sump and in-vessel failure were derived from CASA Grande simulations that are consistent with the specific plant conditions associated with the sequence (i.e., availability of plant equipment, success/failure of operator actions, etc.).

b. Technical basis for concluding that the existing CASA Grande simulation provides results that are applicable or bounding

c. Confirmation that the conditional split fraction value for sump or in-vessel failure were set to 1.0 for non-analyzed cases.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. NUREG 1829 pipe break frequencies for the smallest of the unbounded breaks is used directly in a top-down approach that preserves the exceedance frequencies to determine ACDF. Use of RoverD does not involve the risk assessment parameters that are the subjects of this RAI.

Human Reliability Analysis NOTE: Round 2 RAI question numbers begin with the next sequential number from the April 15, 2014, RAI for this section.

7. RG 1.174, Sections 2.3.1 and 2.3.2 state that the scope and level of detail of the PRA model must be sufficient to model the impact of the proposed change. NRC letter dated April 15, 2014 (ADAMS Accession No. ML14087A075), includes a number of RAIs related to the human reliability analysis (HRA) used in the risk assessment and STPNOC responses to RAIs describe a number of human actions that are important

NOC-AE-15003220 Attachment 1 Page 11 of 16 during a loss-of-coolant-accident (LOCA). Please describe how the dependency among multiple human actions (both those in the "clean plant" and "debris" models) in the same sequence was assessed for the debris PRA model.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7). RoverD does not rely on a difference between a "clean plant" and "as designed" plant analysis in a classic PRA setting, nor does it involve an HRA analysis as described in this RAI. Instead, RoverD relegates all scenarios that result in fine debris more than tested amounts to failure.

Key Assumptions/Key Sources of Uncertainty

1. RG 1.200 defines a "key" source of uncertainty as an issue where no consensus approach or model exists and where the choice of approach or model is known to have an effect on the risk profile (e.g., CDF [core damage frequency], LERF [large early release frequency], ACDF [delta CDF], ALERF [delta LERF]) 1 . RG 1.174 and NUREG-1855, Revision 1, "Guidance on the Treatment of Uncertainties with PRAs in Risk-Informed Decisionmaking," March 2013 (ADAMS Accession No. ML13093A346),

state that "consensus" refers to an approach or model that has a publically available published basis and has been peer reviewed and widely adopted by an appropriate stakeholder group. In addition, widely accepted PRA practices may be regarded as consensus models. Examples include the use of the constant probability of failure on demand model and the Poisson model for initiating events. Finally, models that the NRC has utilized or accepted for the specific application in question can also be considered "consensus."

RG 1.200 defines a key assumption as one that is made in response to a key source of model uncertaintywhere a different reasonable alternative assumption would change the plant's risk profile.

RG 1.200 states that "for each application that calls upon this regulatory guide, the applicant identifies the key assumptions and approximations relevant to that application.

This will be used to identify sensitivity studies as input to the decision-making associated with the application."

Therefore, please provide a table or other structured response that lists key sources of uncertainty. For each key source of uncertainty, please identify the key assumption(s) that were made to address it and provide either a sensitivity study in terms of CDF, LERF, ACDF, and ALERF or use a qualitative discussion as to why a different

'The NRC staffs position is that cases where a consensus model does exist, but the licensee chooses an alternate model also represent key sources of model uncertainty ifthey have an effect on the risk profile.

NOC-AE-1 5003220 Attachment 1 Page 12 of 16 reasonable alternative assumption would not cause the risk acceptance guidelines in RG 1.174 to be exceeded. This response should address:

a. L* approach for chemical effects

b. Head loss correlation

c. Success criteria for fuel blockage and boron precipitation (7.5 grams per fuel assembly (g/FA))

d. Fiber penetration model for sump strainer

e. The use of geometric, rather than arithmetic mean aggregated values from NUREG-1 829, "Estimating Loss-of-Coolant Accident (LOCA) Frequencies Through the Elicitation Process," April 2008 (Volumes 1 and 2: ADAMS Accession Nos. ML082250436 and ML081060300)

f. The continuum break model (vs. double ended guillotine break (DEGB) only model)

g. The quantity and release rate of unqualified coatings The response should evaluate each of these areas one-at-a-time and should include an aggregate analysis that quantifies the integrated impact on CDF, LERF, ACDF, and ALERF from the sensitivity studies that were performed.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure and uses NUREG 1829 pipe break frequency for the smallest of the unbounded breaks to determine ACDF.

Use of RoverD does not involve items a, b, and g, above.

For items c, d, e, and f:

c. Boron precipitation will be addressed in separate submittal.

d. Pipe break frequencies for the quantiles of the arithmetic and geometric NUREG 1829 elicitations are provided in Attachment 7.

e. RoverD uses core fiber accumulation based on measured data and flow rate of the ECCS and core during cold leg break scenarios. The effect on core fiber accumulation of upper and lower bounds of uncertainty for pool concentration and filtration efficiency are provided in Attachment 7.

f. The uncertainty of continuum break versus DEGB is shown in Attachment 7.

NOC-AE-1 5003220 Attachment 1 Page 13 of 16 Validity of Assumption on Pump Configurations

1. In response to question 3, "Plant Configuration," of the April 15, 2014, RAI, STPNOC analyzed different pump configurations for Case 22 to verify Assumption 2b of Volume 3, which stated that a combination of pumps failing in the same train would result in a bounding failure probability compared to other combinations with the same number of each type of pump (i.e., high head, low head, and CS).

The results of this sensitivity showed that the assumption was false for in-vessel failure probabilities. Therefore, non-conservative failure probabilities were assigned to PRA model top events for certain scenarios. This approach may result in an underestimation of the risk of debris.

Failure of the selected pump configuration (Case 22) to uphold assumption 2b calls into question the combinations of the other cases used to simplify the risk assessment.

Therefore:

Please determine whether assumption 2b provides realistic or bounding failure probabilities for each pump state that is assigned a non-unity failure probability.

Please provide CDF, LERF, ACDF, and ALERF using realistic or bounding failure probabilities for all possible pump configuration.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. In RoverD, design basis pump configurations are bounded by the deterministic test data. STPNOC evaluated two additional cases: three train operation and single train operation. The three train configuration is bounded by the deterministic test. However, the single train operation is not bounded by the test. For the single train case, the amount of fiber is one-half the tested amount.

Use of RoverD does not involve quantification of the items in the RAI above.

CASA Grande to PRA Interface

7. The licensee's response to question 5 of the April 15, 2014, RAI, contains a figure showing that the smallest observed break size leading to debris-induced core damage was approximately 17 inches. This appears to conflict with the response to question 1, "Success Criteria," which stated that "the largest break size below which no failures related to either the sump or vessel performance were recorded during the CASA

NOC-AE-1 5003220 Attachment 1 Page 14 of 16 Grande runs was a DEGB in a 5.189 diameter (D) inch pipe." Please clarify these contradictory statements.

Response

For RoverD, the smallest break size that is evaluated for failure is 12.814 inches (DEGB of the surge line). RoverD uses measured test data instead of uncertainty bounds which may result in extreme cases to be evaluated in CASA Grande. RoverD does not rely on a CASA Grande evaluation for failure. CASA Grande exhaustively samples potential break locations to determine the smallest break size that will generate more fibrous debris than was in the deterministic test.

RoverD is described in Attachment 7.

Fidelity between RELAP Simulations and CASA Grande I. Volume 6.2 describes the RELAP simulations that were used to determine whether core cooling could be accomplished with partial or complete blockage. Page 123 states that "all the safety systems were assumed to be available throughout the transient."

Therefore, it would appear that Table 2.5.39, "Core Blockage Scenarios Summary,"

(Volume 6.2) would only apply to scenarios where all ECCS and CS pumps are available (i.e., Case 1). The response to question 1, "Success Criteria," of the April 15, 2014, RAI, states that "analyses performed in support of the LAR included consideration of a 6 inch hot leg break with only one train of ECCS available." [emphasis added]. Please clarify if this refers to an analysis performed subsequent to the LAR. Provide additional details on this or any other analyses that are used to justify applying the results of Table 2.5.39 to pump states other than Case 1. Include a description on the quality assurance of these analyses in relationship to question 1, "Success Criteria."

Response

The analysis discussed in this RAI was originally performed in July 2014, subsequent to the submittal of the November 2013 LAR. The quality assurance for the analysis is consistent with the description of the TAMU quality program aspects in the response to RAI 4 in the preceding Project Quality Assurance RAIs. The analysis is included as an enclosure to this attachment.

As described in Attachment 7, RoverD uses thermal-hydraulic analyses to show that all small breaks and all hot leg breaks are success based on PCT.

RoverD does not rely on fidelity with CASA Grande for success criteria.

Use of RoverD applies the deterministic testing to evaluate bypass and blockage.

NOC-AE-1 5003220 Attachment 1 Page 15 of 16 State-of-Knowledge Correlation

1. RG 1.174 Section 2.5.2 states that the state-of-knowledge correlation should be accounted for unless it can be shown to be unimportant. In question 5, "Uncertainty Analysis," of the April 15, 2014, RAI, the NRC staff requested the licensee to clarify why the state-of-knowledge correlation was not applied to the LOCA frequencies used by the PRA and CASA Grande. STP's response stated that "...dependence of the PRA and CASA Grande on different parameters of the LOCA break frequencies is sufficient so as not to warrant correlation between the PRA and CASA Grande."

This answer may not be inaccurate because the choice of LOCA frequency percentile affects both the absolute LOCA frequency (used by the PRA) and the shape of LOCA frequency versus break size curve (used by CASA Grande). Therefore, both the PRA and CASA Grande rely on the same underlying parameter and the state of knowledge correlation applies. This position was communicated to the licensee by the Advisory Committee on Reactor Safeguards (ACRS) during the meeting on September 3, 2014 (ADAMS Accession No. ML14266A510), and by the NRC staff during the audit conducted from September 15-17, 2014. Please revise your analysis by correlating the LOCA frequencies used by the PRA and CASA Grande. Please also provide updated CDF, LERF, ACDF, and ALERF based on mean values resulting from the parametric uncertainty calculation that properly considers the correlation between the initiating event frequencies and the failure probabilities (sump and in-vessel) for debris-related events.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande coupled to the PRA to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure and uses NUREG 1829 pipe break frequency for the smallest of the unbounded breaks to determine ACDF. The application of RoverD eliminates the need to account for state-of-knowledge for LOCA frequencies since STP is only applying LOCA frequency as determined from NUREG 1829.

NOC-AE-1 5003220 Attachment 1 Page 16 of 16 Selection of Johnson Parameters

1. In the response to question 4, "Uncertainty Analysis," of the April 15, 2014, RAI, STPNOC stated that it was not possible to approximate the NUREG-1 829 mean frequencies with different selections of the parameter k. NRC independent analyses indicate otherwise; for example, the following alternative fits yields means that are relatively close to those tabulated in Table 2.2.2 of the Volume 3 submittal. Please evaluate the sensitivity of the CDF and LERF on different selections of bounded Johnson distribution fits, such as the alternative fit in the table below.

Median Mean 9 5 th Size (in) 5 th (llyr) (llyr) (llyr) (l/yr) y 6 0.5 0.000068 0.00063 0.001853 0.0071 4.962538 0.671235 1.49E-05 1 1.625 5E-06 8.9E-05 0.000408 0.0016 4.551311 0.568039 8.48E-08 0.268427 2 3.69E-06 6.57E-05 0.000301 0.00118 4.594371 0.568322 5.61E-08 0.212914 3 2.1E-07 3.4E-06 1.59E-05 6.1E-05 6.024348 0.568377 2.31E-08 0.135431 6 6.3E-08 1.08E-06 5.16E-06 1.98E-05 6.194246 0.56465 4.59E-09 0.062491 7 1.46E-08 3.04E-07 1.67E-06 6.34E-06 6.529987 0.541377 1.4E-11 0.052616 14 4.1E-10 1.2E-08 1.94E-07 5.8E-07 6.142561 0.422624 1.69E-10 0.024278 31 3.5E-11 1.2E-09 3.21E-08 8.1E-08 6.207166 0.389148 1.77E-11 0.01

Response

RoverD evaluation of Delta CDF and Delta LERF frequencies are not developed from sampling a Johnson distribution. Instead, they are taken directly from the NUREG 1829 table for the geometric mean aggregation. In Section 4.3 of Attachment 7, the quantiles for both the arithmetic and geometric aggregation are shown for all quantiles developed from the NUREG 1829 elicitation. The STP PRA Model of Record determination of plant average CDF and LERF is unchanged in RoverD.

NOC-AE-1 5003220 Attachment 1 Enclosure Enclosure to RAI I to Fidelity Between RELAP Simulation and CASA Grande South Texas Project Risk-Informed GSI-191 Evaluation Core Blockage Thermal-Hydraulic Analysis Hot Leg Medium Break (6-inch) LOCA w/ Dual ECCS Injection Train Failure

NOC-AE-1 5003220 Attachment 1 Enclosure South Texas Project Risk-Informed GSI-191 Evaluation Core Blockage Thermal-Hydraulic Analysis Hot Leg Medium Break (6-inch) LOCA w/ Dual ECCS Injection Train Failure AT I ENGINEERING NUCLEAR

b. iTEXAS A&M UNIVERSITY ENGINEERING Role Nome Author Timothy Crook Reviewer Rodolfo Vaghetto Department of Nuclear Engineering Texas A&M University College Station, Texas 77843-3113 Doc # - TAM U-STP-6in-Dual-Train-Fail-Blockages-vO.2 March 2015 1

NOC-AE-1 5003220 Attachment 1 Enclosure Revision History Revision 0.1 - July 2014: First Release Revision 0.2 - March 2015: Revision 2

NOC-AE-15003220 Attachment 1 Enclosure Contents

1. PURPOSE ................................................................................................................................................... 5

2. INPUT M ODEL AND SIM ULATION CONDITIO NS ................................................................................... 6 2.1 ECCS and Train Failure Configuration ............................................................................................. 6

3. SIM ULATION RESULTS ............................................................................................................................... 8

3. COM MENTS ............................................................................................................................................. 10 APPENDIX A - Core Blockage Therm al-Hydraulic Analysis .................................................................... 11 3

NOC-AE-1 5003220 Attachment 1 Enclosure List of Figures:

Figure 1. RELAP5-3D Safety Injection Nodalization Diagram (X = loop number = 2, 3, or 4) ................... 6 Figure 2. Peak Cladding Tem perature ..................................................................................................... 8 Figure 3. Prim ary System Pressure ......................................................................................................... 9 Figure 4. SI and Break Flow Rate .......................................................................................................... 9 Figure 5. Steam Generators' Liquid Fraction ........................................................................................ 10 4

NOC-AE-1 5003220 Attachment 1 Enclosure

1. PURPOSE This document describes the simulation results of a Medium Break (6-inch) LOCA scenario in hot leg under a hypothetical instantaneous full core and core bypass blockage using the RELAP5-3D input model. This document is a continuation of the simulation analysis previously conducted by Texas A&M University using the same RELAPS-3D input model and similar simulation techniques reported in Attachment 1. The break size and location for this simulation (6-inch in hot leg of the loop 3 equipped with SI train) was chosen among the core scenarios where the peak cladding temperature (output parameter used a figure of merit to judge the final outcome of the simulation) was found to be maintained below the limit of 800

°F at any time after the core blockage time (Sump Switchover time). The simulations described in were performed under the assumption of full availability of the three SI trains. The main scope of this additional simulation was to study any effect of the SI pumps unavailability on the core coolability under a hypothetical core and core bypass blockage scenario. In particular a dual-train failure mode was assumed to occur at the beginning of the transient.

The results of the simulation are presented in terms of the following parameters:

• RCS pressure

• Break mass flow rate and Total SI mass flow rate

• Peak clad temperature

" Steam generator U-tube void fraction 5

NOC-AE-1 5003220 Attachment 1 Enclosure

2. INPUT MODEL AND SIMULATION CONDITIONS A detailed description of the RELAP5-3D input model, the simulation technique adopted to simulate the core blockage at the bottom of the core, other relevant timings and simulation conditions are listed in Appendix A. Section 2.1 reports the most relevant conditions adopted for the simulation described in this report, and in particular for the 6-inch hot leg break.

2.1 ECCS and Train Failure Configuration The nodalization diagram adopted for the ECCS, including charging pumps, SI pumps, RHR pumps, and RHR heat exchangers, is shown in Figure 1. Trip control functions were defined to switch between the phases of the injection (Safety injection, cold leg (CL) recirculation, and hot leg (HL) recirculation). Loops are identified with numbers. The loops equipped with SI system are loop 2, 3, and 4. The break was assumed to occur in the hot leg of the loop 3.

Hot Leg Accumulator x=2,3, and 4 RWST I Containment I HPSI Pump sump TDJ x45 I Exchanger Figure 1. RELAP5-3D Safety Injection Nodalization Diagram (X = loop number = 2, 3, or 4) 6

NOC-AE-1 5003220 Attachment 1 Enclosure The RELAP5-3D ECCS includes the following features for each train:

- One Accumulator simulated using the accumulator component (Components x90). A control variable was defined in order to isolate the accumulator to account for special LOCA manual operation procedures.

- One high pressure safety injection (HHSI) injecting directly to the primary system. The pump was modeled with a time-dependent junction (X45) where a table of the velocity of the liquid to be injected as a function of the pressure of the primary system injection location was defined.

- One low pressure safety injection (LHSI, TDJ x46) injecting into the primary system through the residual heat removal (RHR) exchanger. This pump was modeled with the same approach applied to the HHSI.

- One RHR exchanger, connected downstream the LHSI pump simulated with one pipe component (X47) for the tube side of the heat exchanger, one pipe component (X63) for the shell side of the heat exchanger and one heat structure, connected to both pipes to simulate the heat exchanger tube walls. The Component Cooling Water (CCW) thermal-hydraulic conditions were imposed through a time-dependent volume (X61) and its mass flow rate was imposed through a time-dependent junction (X62).

To account for the failure of two Sl trains, the flow rate tables of the time-depended junction modeling the HHSI and LHSI pumps in the failing trains were modified to have zero mass flow rate at all primary system pressures (no injection). This results in no flow and no Sl contribution from modified injection trains. The trains connected to loop 3 and 4 were assumed to fail in this simulation.

NOTE: Accumulators were not modified in accounting for train failure as they are passive systems and would not be affected by pump or power failure.

7

NOC-AE-1 5003220 Attachment 1 Enclosure

3. SIMULATION RESULTS As mentioned above, an instantaneous core and core bypass blockage at the bottom of the pipe components simulating the regions, was assumed at the sump switchover time. The sump switchover time for this scenario was equal to tsso = 7420 seconds (after the break opening event). The next available restart time (see Appendix A for more details on the core blockage time) for this simulation to impose the total blockage at the bottom of core and core bypass was equal to 7500 seconds.

The peak cladding temperature for this scenario is plotted in Figure 2. In the same figure the core blockage time (dotted line) is also plotted.

800 a- 700

-1 Train - Full Core Blockage @ 7500s 600 o

5o0 ....-. 1 Train Core Blockage Time E

I- 400 ii "0

300 U 200 lOO a-100 0

0 2500 5000 7500 10000 12500 15000 17500 20000 22500 Time (s)

Figure 2. Peak Cladding Temperature The primary system pressure during the transient is shown in Figure 3.

8

NOC-AE-1 5003220 Attachment 1 Enclosure 500

-1 Train - Free Bypass Blockage @ 7500s 450 400 ....-. 1 Train Core Blockage Time 350 300 U,

250 200 E 150 1100 50 0 2500 5000 7500 10000 12500 15000 17500 20000 22500 Time (s)

Figure 3. Primary System Pressure Figure 4 shows the total break mass flow rate as a function of the time (dark red curve) and the total SI flow rate (through train 2).

2000 - 1 Train - Full Core Blockage - Break 1 Train - Full Core Blockage - SI Total 1800 160-.. 1 Train Core Blockage Time 1600 E*1400

'1200 Cr 1000 02 800 U,

600 400 200 0I 0 2500 5000 7500 10000 12500 15000 17500 20000 22500 Time (s)

Figure 4. SI and Break Flow Rate The liquid fraction of the upper region of the U-tube for each of the four steam generator (see Appendix A for nodalization diagram) is plotted in Figure 5 9

NOC-AE-1 5003220 Attachment 1 Enclosure

-1 Train - SG1 0.8 C

0 -1 Train - SG2 m 0.6 U-

"10 - 1 Train - SG3

_ 0.4 1 Train - SG4 0.2

....-. 1 Train Core Blockage Time 0 . .._o l. .1 0 2500 5000 7500 10000 12500 15000 17500 20000 22500 Time (s)

Figure 5. Steam Generators' LIquid Fraction

3. COMMENTS A simulation of a 6-inch break LOCA in hot leg under a hypothetical core blockage was performed using the RELAP5-3D input model and simulation techniques described in Appendix A. Under the simulation conditions described in Appendix A and the additional assumption of dual-train failure described in Section 2, the peak cladding temperature was estimated to be maintained below 800 °F during the period simulated after the core blockage time.

10

NOC-AE-15003220 Attachment 1 Enclosure APPENDIX A - Core Blockage Thermal-Hydraulic Analysis 11

NOC-AE-1 5003220 Attachment 1 Enclosure 5TP South Texas Project Risk-Informed GSI-191 Evaluation Core Blockage Thermal-Hydraulic Analysis Document: STP-RIGSI191 Revision: 2.1 Date: January, 2013 Prepared by:

Rodolfo Vaghetto, Texas A&M Reviewed by:

Yassin, A. Hassan, Texas A&M Rodolfo Vaghetto, Texas A&M Andrew Franklin, Texas A&M Ernie J. Kee, South Texas Project Zahra Mohaghegh, Soteria Consultants Seyed A. Reihani, Soteria Consultants Approved by:

Steve Blossom, South Texas Project Rick Grantom, South Texas Project 12

NOC-AE-1 5003220 Attachment 1 Enclosure Core Blockage Thermal-Hydraulic Analysis Role Author Name AIM 1 Rodolfo Vaghetto Bi 1 Supervisor Yassin. A. Hassan A report submitted by Yassin A. Hassan Department of Nuclear Engineering Texas A&M University College Station, Texas 77843-3113 Phone: 979 845 7090 Email: y-hassanCatamu.edu Revision 2.1: January 2013 13

NOC-AE-1 5003220 Attachment 1 Enclosure Contents REV ISION HIST O RY ........................................................................................................................................ 4 1 . PURPOSE ................................................................................................................................................... 5

2. RELAP5-3D MODELS and SIM ULATIONS ................................................................................................... 5 2.1. 3D Vessel - 1D Core Model Description ...................................................................................... 6 2.2. 3D Vessel - 3D Core Model Description ...................................................................................... 8 2.3. Simulations Approach ............................................................................................................... 9

3. ANALYSIS with 3D VESSEL - ID CORE MODEL .................................................................................... 10 3.1. Small Break (2") Cold Leg Break Scenario Simulation Results ..................................................... 11 3.2. Small Break (2") Hot Leg Break Scenario Simulation Results ...................................................... 14 3.3. M edium Break (6") Cold Leg Break Scenario Simulation Results ................................................ 17 3.4. Medium Break (6") Hot Leg Break Scenario Simulation Results ................................................. 20 3.5. Large Break (DEG) Cold Leg Break Scenario Simulation Results ................................................ 23 3.6. Large Break (DEG) Hot Leg Break Scenario Simulation Results ...................................................... 26 3.7. Comments to the 3D Vessel - 1D Model Simulation Results ..................................................... 29

4. ANALYSIS with 3D VESSEL - 3D CORE MODEL .................................................................................... 32 5 . REFE RENCES ............................................................................................................................................ 37 14

NOC-AE-1 5003220 Attachment 1 Enclosure REVISION HISTORY November 2012: 1.0 First Release.

January 2013: 2.0 Comments and modifications from the internal review implemented.

January 2013: 2.1 Figures revised.

15

NOC-AE-1 5003220 Attachment 1 Enclosure

1. PURPOSE Thermal-hydraulic calculations have been conducted with the RELAP5-3D [1) system code to analyze the reactor system response under hypothetical core blockage scenarios during a Loss of Coolant Accident (LOCA). The purpose of these calculations was to:

1) Identify the scenarios which may produce an increase in the peak cladding temperature and, subsequently, a potential core damage among selected LOCAs of different break sizes and locations under full core and core bypass blockage.

2) For the cases identified in 1), analyze the system response under a partial core blockage hypothesis.

2. RELAP5-3D MODELS and SIMULATIONS Two RELAP5-3D models were developed and used to conduct the simulations. The 3D Vessel - 10 Core model (described in section 2.1) was selected to run the basic simulations of the LOCA transients under a hypothesized full core and core bypass blockage. This model was selected because it combines the detailed nodalization of the vessel (using multi-dimensional components available in RELAP5-3D) accounting for more realistic injection flow paths, with the one-dimensional core and core bypass to minimize the simulation time. The following basic scenarios were simulated using the 3D Vessel - 1D Core model:

• Small Break (2") in Cold Leg.

• Small Break (2") in Hot Leg.

• Medium Break (6") in Cold Leg.

• Medium Break (6) in Hot Leg.

• Double-Ended Guillotine (DEG) Break in Cold Leg.

• Double-Ended Guillotine (DEG) Break in Hot Leg.

Additional simulations were conducted to study the thermal-hydraulic behavior of the core under partial core blockage for a selected case, using the 3D Vessel - 3D Core model (described in section 2.2). This model simulates the reactor core with multi-dimensional components, allowing partial core blockage (by fuel channel) with a relatively larger simulation time. Both models used for these simulation sets were originated from a Full 1D model, which is described in details in [2, 3].

16

NOC-AE-1 5003220 Attachment 1 Enclosure 2.1. 3D Vessel - 1D Core Model Description Figure 1 shows the nodalization diagram adopted in this model. Some of the regions of the vessel (identified with colored blocks) were simulated using multi-dimensional hydrodynamic components available in RELAP5-3D.

Figure 1. Vessel and Core Nodalization (3D Vessel - 1D Core model)

As Figure 1 clearly demonstrates, the downcomer was split into two components (515 and 521) and modeled with two cylindrical multi-dimensional components having 1 radial node, 20 azimuthal nodes, and 1 and 10 axial nodes respectively. The cold legs (blue arrows in Figure 1) were connected to four branch components (501, 502, 503, and 504) which in turn were connected to the upper volume of the downcomer (515). The lower plenum was also modeled with two cylindrical multi-dimensional components (535 and 525), each one characterized by 1 axial node and 20 azimuthal nodes. To account for the spherical shape of the lower head, the bottom section of the lower plenum (525) has one less radial node (7 nodes) compared to the top section (535) which has 8 radial nodes. There are three junctions defined for the component 545, connected to the core average (605), core hot (606) and core 17

NOC-AE-1 5003220 Attachment 1 Enclosure bypass (551). Proper flow areas, hydraulic diameters, and k-loss coefficients were defined in these junctions to simulate the flow path from the lower plenum to the mentioned channels. Finally, the section of the upper plenum where the hot legs (red arrows in Figure 1) are connected was simulated using a multi-dimensional cylindrical (vessel exit, 865) component having 8 radial nodes, 20 azimuthal nodes and 1 axial node. Most of the regions of the upper plenum were simulated using one-dimensional components except for the vessel exit (component 865) which was modeled with a multi-dimensional cylindrical component. Junctions connecting each of the vessel inlet volumes (501, 502, 503, and 504) to the upper plenum were defined in order to simulate the flow bypass from the inlet to the vessel upper head. Table 1 summarizes the geometry and the number of nodes for the components described above.

Table 1. Reactor vessel Components and Nodes Naumb"rof Nods Mdia0 Azmtha0 l ial Downonw 515 20 1 1 20 11 521 200 1 20 10 535 160 8 20 1 525 140 7 20 1 865 160 8 20 1 The nodalization of the reactor core was based on the nodalization of a typical PWR core available in the RELAP5 user manuals. The reactor core was modeled using two one-dimensional pipe components. The pipe 605 simulates the average channels, where 192 assemblies were lumped together, and the pipe 606 was used to simulate the hot channel. One heat structure was connected to the pipe 605. Two heat structures were connected to the pipe 606 to account for the hot rod and for the remaining rods in the hot channel. The axial and radial power shapes were calculated from documentation provided by STP for units 1 and 2, where the power for each fuel channel is described for the fuel cycle 17 at different burnups. For the purpose of these calculations, the highest burnup (end of cycle) was selected. The selection of the highest burnup should provide the highest decay power at the reactor shutdown. Radial peaking factors were applied to distribute the total power of the reactor within the average channels and the hot channel (hot rod and average rods in hot channel). Twenty-one axial nodes were used for the hydrodynamic components 605 and 606 and the same number of nodes for the related heat structures. The core bypass (component 551), the core hot channel (component 606), and the core average channel (component 605) are connected to the core inlet region (component 545) with three independent junctions (called 54501, 54502, and 54503 respectively). It has to be noted that no core cross flow is simulated between the two channels representing the core in this model. The core blockage was simulated by imposing a large k-loss coefficient at these junctions as it will be described in section 2.3. All the other components of the primary system not shown in Figure 1 (such as hot and cold legs, steam generators, Safety Injection System) were simulated using the same nodalization described in [3].

18

NOC-AE-1 5003220 Attachment 1 Enclosure 2.2. 3D Vessel - 3D Core Model Description The nodalization adopted for the 3D Vessel - 1D Core model is shown in Figure 2. The model was generated from the 3D Vessel - 1D core nodalization and modified in order to represent additional vessel regions with multi-dimensional components. Such regions are:

" The reactor core. The core was simulated using four Cartesian multi-dimensional components (605, 606, 607 and 608). This nodalization allowed the representation of 193 fuel channels (blue region in Figure 2, red box on right), accounting for axial and horizontal (x and y directions) coolant flow. Each fuel channel was subdivided in 11 axial nodes.

" The lower and upper core plates. These regions were simulated using a Cartesian multi-dimensional component (545 and 845 respectively) with 193 channels and only one axial node.

Such components were connected via multiple junctions with the reactor core and with the other components of the vessel as shows in Figure 2.

I Wý

_10 H 1111, 141 Figure 2. Vessel and Core Nodalization (3D Vessel - 3D Core model)

A realistic power distribution was imposed in the heat structures representing the fuel elements (one per fuel channel. Figure 3 depicts the provided core power distribution which was implemented in the model. The fuel channels are marked with different colors, each one referring to a specific power sharing.

19

NOC-AE-1 5003220 Attachment 1 Enclosure Figure 3. 3D Core Power Map (Channels marked with the same color have the same power sharing) 2.3. Simulations Approach Each LOCA scenario was simulated using a sequence of three steps.

STEP 1. Steady-state Phase. The steady-state condition (nominal operation) of the reactor is simulated at this step to provide the initial conditions for the LOCA simulation.

STEP 2. Blow-Down Phase. This simulation is started from the end of the steady-state simulation using the restart option of RELAP5. After an additional steady-state period of 300 s, the break is assumed to open instantaneously. The simulation is continued past the sump switchover time where a control variable automatically switches the Safety Injection suction from the RWST to the sump conditions. The first available restart after the sump switchover time is used to run the long-term cooling phase where the core blockage was assumed.

STEP 3. Long-Term Cooling with Core Blockage. Starting from the first available restart time from the simulation of step 2, a new restart case was conducted to simulate the long-term cooling phase up to 100000 s (approximately 24h after the sump switchover time). At the time of restart, all the junctions at the core and core bypass inlet were re-defined in the restart input file to impose an adequate forward k-loss coefficient to produce a total blockage of the coolant flow. The value of such k-loss coefficient was determined by running preliminary simulations. The final value of the forward k-loss coefficient to be applied to the mentioned junctions to produce a total coolant blockage was found to be 1.0-108. It has to be remarked that the core blockage is assumed to occur at the beginning of the first available restart 20

NOC-AE-15003220 Attachment 1 Enclosure after the sump switchover time. The restart time changes with the break size and it is usually at approximately few hundred seconds from the sump switchover time.

This approach was applied for all the scenarios listed in section 2. The break location, for either the cold and hot leg cases, was assumed to be located at the horizontal section of the leg, near the reactor vessel in one of the loops equipped with Safety Injection (loop 3). In all the cases, the break orientation was imposed at the bottom of the leg. In all the models used for the simulations, all the safety systems were assumed to be available throughout the transient.

3. ANALYSIS with 3D VESSEL - 1D CORE MODEL As mentioned, the simpler 3D Vessel - 10 Core model was used to run the simulations of the basic cases listed in section 2. After the sump switchover occurred, the simulation was stopped and the first restart available was selected to run the long-term cooling phase. At this time, a full core and core bypass blockage was assumed by imposing a large forward k-loss coefficient in the junctions 54501, 54502, and 54503 (see section 2.1 for details) which represent the core bypass and core inlets. The simulation was extended for approximately 24h after the sump switchover time. The following parameters were extracted and will be presented as results of the simulations:

" Primary Pressure

" Total SI (Low Head Injection + High Head Injection Pumps + Accumulators) flow rate

" Total Break Flow Rate

" Steam Generators Liquid Inventory (Top Volume Liquid Fraction)

" Maximum Peak Cladding Temperature

" Core inlet/outlet Coolant Temperatures

" Core Outlet Saturation Temperature

" Time to sump switchover

" Time to Hot leg Injection Switchover In particular, the maximum peak cladding temperature (calculated as the maximum temperature of all the heat structure cladding nodes in the three heat structures of the core) was monitored right after the core blockage time to check the increase in the temperature due to the change in the core coolant flow.

21

NOC-AE-1 5003220 Attachment 1 Enclosure 3.1. Small Break (2") Cold Leg Break Scenario Simulation Results Figures 4 to 7 present the simulation results for the 2" cold leg break in terms of primary pressure, flow rates (SI and break), steam generator liquid inventory, and maximum peak cladding temperature respectively.

2.5E+03 - Primary Pressure

- Time to Sump Switchover

- - - Time to Hot Leg Injection 2.0E+03 ...... Trme of Core Blockage 1.SE+03

- 1.OE+03 5.OE+02 0.0E+00 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 Time [s)

Figure 4. Primary Pressure (2" Cold Leg Break) 22

NOC-AE-1 5003220 Attachment 1 Enclosure Figure 5. Mass Flow Rates: Total SI and Break Flow (2" Cold Leg Break) 1.2 -

1 I 0.8 . -SG .

S-5SO2 I

.0

-SG3 I U. 0.6 - G 7 *-Time to Sump Switchover 0.4 --- Time to Hot Leg Injection Time to Core Blockage 0.2 0-0 5000 10000 15000 20000 25000 30000 35000 40000 Time [s]

Figure 6. Steam Generators Liquid Inventory: Top Volume Liquid Fraction (2" Cold Leg Break) 23

NOC-AE-1 5003220 Attachment 1 Enclosure 800o 700 700 600 600 Soo 300

400 40 . ..... ..

200 100 0

10000 10500 11000 11500 12000 125W0 13000 13500 14000

-t 200

- Core outlet

-- Core outl*t Saturation - PCT 100

-Time to S+mp Switchover -- -Time to Hot Leg Injection

...... Time to C~re Blockage 0 4-9000 14000 19000 24000 29000 34000 39000 44000 49000 Time Is)

Figure 7. Temperatures (2" Cold Leg Break) 24

NOC-AE-1 5003220 Attachment 1 Enclosure 3.2. Small Break (2") Hot Leg Break Scenario Simulation Results Figures 8 to 11 show the primary pressure, flow rates (SI and break), steam generator liquid inventory, and maximum peak cladding temperature respectively for the 2" hot leg break scenario.

2.5E+03

-Primary Pressure 2.OE+03 Timeto Sump switchover

- - - Time to Hot Leg Injection

...... Time to CoWe Blockage w 1.5E+03 a.

" 1.OE+03 5.OE+02 O.OE+00 p 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 Time [s]

Figure 8. Primary Pressure (2" Hot Leg Break) 25

NOC-AE-1 5003220 Attachment 1 Enclosure 900 800 700

, 600

.0 U 2500 3

.o400 S300 200 100 0

0 5000 10000 15000 20000 25000 30000 3SO00 40000 Time [s]

Figure 9. Mass Flow Rates: Total SI and Break Flow (2" Hot Leg Break) 1.2 .

• I 0.8 - G61

.0 4SGI i 0.6-27 -Time to Sump Switchover 0.4 .. -. to.HotLegnjectaon, Time to Core Blockage 0.2 0 5000 10000 15000 20000 25000 30000 35000 40000 Time [s m Figure 10. Steam Generators Liquid Inventory: Top Volume Liquid Fraction (2" Hot Leg Break) 26

NOC-AE-1 5003220 Attachment 1 Enclosure Figure 11. Temperatures (2" Hot Leg Break) 27

NOC-AE-1 5003220 Attachment 1 Enclosure 3.3. Medium Break (6") Cold Leg Break Scenario Simulation Results Figures 12 to 15 show the primary pressure, flow rates (SI and break), steam generator liquid inventory, and maximum peak cladding temperature respectively for the 6" cold leg break scenario. For this particular scenario, the simulation stopped at approximately 5500s (about 1000 s after the core blockage time) due to the increase of the peak cladding temperature (see Figure 15) which exceeded the thermal properties table temperature range define in the RELAP5 input. All the plots for this simulation case show the time range for the horizontal axis up to this time.

2.5E+03

- Primary Pressure

- Time to Sump Switchover

...... Time to Core Blockage 2.OE+03

~.1.OE+03 5.OE+02 0.OE+00 5000 4000 0 1000 2000 3Tm[

3000 4000 5000 Time [s]

Figure 12. Primary Pressure (6" Cold Leg Break) 28

NOC-AE-1 5003220 Attachment 1 Enclosure 4000 3500 3000

. 2500 2000 0

1500 1000 So 0

0 1000 2000 3000 4000 5000 Time [s]

Figure 13. Mass Flow Rates: Total SI and Break Flow (6" Cold Leg Break) 1.2 1

-- SG 1

-SG 2 0.8

-SG 3 0

U--SG4

1. 0.6

9 1- Time to Sump Switchover

...... Time to Core Blockage 0.4 0.2 0

0 1000 2000 3000 4000 5000 Time [s]

Figure 14. Steam Generators Liquid Inventory: Top Volume Liquid Fraction (6" Cold Leg Break) 29

NOC-AE-1 5003220 Attachment 1 Enclosure I Core inlet

-Core outlet 700 ... . a C e o..tt. .i I Core outlet Saturation 600

- 500 ...

• sa0 U.

,~400 0.

'300 -

200 100 0

3000 3500 4000 4500 5000 5500 Time Is]

Figure 15. Temperatures (6" Cold Leg Break) 30

NOC-AE-15003220 Attachment 1 Enclosure 3.4. Medium Break (6") Hot Leg Break Scenario Simulation Results The primary pressure, flow rates (SI and break), steam generator liquid inventory, and maximum peak cladding temperature are plotted in Figures 16 to 19 respectively for the 6" hot leg break scenario.

Z.SE+03 2.OE+03 - Primary Pressure

- Time to Sump Switchover

-- - Time to Hot Leg Injection 1.5E+03 ,-"., Time to CoreiBlockage 0.

- 1.OE+03 5.OE+02 0.OE+0, 0 5000 10000 15000 20000 25000 30000 Time [sJ Figure 16. Primary Pressure (6" Hot Leg Break) 31

NOC-AE-1 5003220 Attachment 1 Enclosure 4000...

- Total Safety Injection 1 3500

- Break

- Time to Sump Switchover

- - - Time to Hot Leg Injection 2500 *..Time to Core Blockae

.2 1500 1000 500 .

0

• 0 5000 10000 15000 20000 25000 30000 Time [s]

Figure 17. Mass Flow Rates: Total SI and Break Flow (6" Hot Leg Break) 1.2 1-I MI 0.8 -SG 1

-II

.0 t -SG3 1 Z0.6 -56 0 cr -Time to Sump Switchover 0.4 - - - TimeUto Na eg injectionj Time

.......... to Core Block 0.2 0 5000 10000 15000 20000 25000 30000 Time [s]

Figure 18. Steam Generators Liquid Inventory: Top Volume Liquid Fraction (6" Hot Leg Break) 32

NOC-AE-1 5003220 Attachment 1 Enclosure 800 v

-Core inlet 700W

-Core outlet 700

-Core outlet Saturation 500 ...  :...

600

-Time to Sump Switchover U.

200

...... Time to Core Block 100

~ 0, E

IM200 jr I -

3000 3500 4000 4500 500 5500 600 I

Lv 100 V fi I..

3000 8000 13000 23000 280W Time [s)

Figure 19. Temperatures (6" Hot Leg Break) 33

NOC-AE-1 5003220 Attachment 1 Enclosure 3.5. Large Break (DEG) Cold Leg Break Scenario Simulation Results Figures 20 to 23 show the primary pressure, flow rates (SI and break), steam generator liquid inventory, and maximum peak cladding temperature respectively for the DEG cold leg break scenario. Similarly to what predicted for the 6" cold leg scenario, the simulation stopped at approximately 3500s (about 1000 s after the core blockage time) due to the increase of the peak cladding temperature (see Figure 23) which exceeded the thermal properties table temperature range define in the RELAP5 input. All the plots for this simulation case show the time range for the horizontal axis up to this time.

2.5E+03 2.E+03 - Primary Pressure

- Time to Sump Switchover

- -- Time to Hot Leg Injection 1.5E+03 ...... Time to Core Blockage 0.

" 1.OE+03 5.OE+02 O.OE+00 0 500 1000 1500 2000 2500 3000 3500 4000 Time [s)

Figure 20. Primary Pressure (DEG Cold Leg Break) 34

NOC-AE-1 5003220 Attachment 1 Enclosure 40000 -r 35000

- Total Safety Injection 30000-1 Break 25000 - Time to Sump Switchover

- - -Time to Hot Leg Injection S20000 ...... Time to Core Blockage 0

15000 10000 4 SN0-1 0

,11.I1i IýIWAlh -.

~IIflflNU.ULJ~JLILflJIflI~

AA AI~IhA nrvu, I~ I Iii mvIiJl, LAI IL W""

~

• I IUU 1W1W I A L

Wwý 0 500 1000 1500 2000 2500 3000 3500 4000 Time [s]

Figure 21. Mass Flow Rates: Total SI and Break Flow (DEG Cold Leg Break) 1.2

-SG 1 1

-SG3 0.8 - SG4 C

o /- Time to Sump Switchover 4.1

. 0.6 Time to CoreBlockage.

0.4 0.2 0 500 1000 1500 2000 2500 3000 Time [s]

Figure 22. Steam Generators Liquid Inventory: Top Volume Liquid Fraction (DEG Cold Leg Break) 35

NOC-AE-1 5003220 Attachment 1 Enclosure B0o

-Core inlet 700 Core outle

-Core outlet Saturation 600-  : l- PCT

-SO- rime to Sump Switchover L.i- - -- Time to Hot Leg -jection 1300_

200 100 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 Time [s)

Figure 23. Temperatures (DEG Cold Leg Break) 36

NOC-AE-1 5003220 Attachment 1 Enclosure 3.6. Large Break (DEG) Hot Leg Break Scenario Simulation Results Figures 24 to 27 show the primary pressure, flow rates (SI and break), steam generator liquid inventory, and maximum peak cladding temperature respectively for the DEG hot leg break scenario.

2.5E+03 2.0E+03 - Primary Pressure I

- Time to Sump Switchover

-- - Time to Hot Leg Injection 1.*.03 ... Trme to Core Blockage 0.

o 1.OE+03 5.OE+02 O.OE+00 -LL 0 5000 10000 15000 20000 25000 30000 Time [s]

Figure 24. Primary Pressure (DEG Hot Leg Break) 37

NOC-AE-1 5003220 Attachment 1 Enclosure 49000

-Total Safety Injection

- Break 39000 -Time to Sump Switchover

- - --Time to Hot Leg Injection

...... Time to Core Blockage

,.2 19000 9000

-1000 0 5000 10000 15000 20000 25000 30000 Time [s]

Figure 25. Mass Flow Rates: Total SI and Break Flow (DEG Hot Leg Break) 1.2 1 .

- SG1 0.8 . .

.0I - SG3 I *SG4

u. 0.6 -4..

- Time to Sump Switchover

,r

- - - Time to Hot Leg Injection 0.4...... Time to Core Blockage 0.2 0 10000 20000 30000 40000 50000 60000 Time [s]

Figure 26. Steam Generators Liquid Inventory: Top Volume Liquid Fraction (DEG Hot Leg Break) 38

NOC-AE-1 5003220 Attachment 1 Enclosure a00* 100 700

-Core inlet 700 500 Core outlet Core outlet Saturation 600

- PCT 30W

- miezo Sump Swfitchowe

- - -Time to Hot Leg Injection 100 2~N 200 300 350ONE0 I.0 0., .....to eorsMocarge 0 O0 E -A 2500 MMO 3500 4000 300, w 14- 99 200 100 0

2000 7000 12000 17000 22000 27000 Time Is]

Figure 27. Temperatures (DEG Hot Leg Break) 39

NOC-AE-15003220 Attachment 1 Enclosure 3.7. Comments to the 3D Vessel - 1D Model Simulation Results Table 2 summarizes the results described in sections 3.1 to 3.6 by associating the success of the simulation with the maximum peak cladding temperature. All the cases which produced a peak cladding temperature increase due to the core blockage which did not exceed 800 °F were assumed to be successful cases which may not lead to core damage. The case where the maximum peak cladding temperature was found to diverge after the core blockage time (exceeding the limiting temperature of 800 °F) were considered failing cases which may lead to core damage.

Table 2. Summary of the Results Break Location BreakSize Cold Leg HotLe Medium (6")

Large (DEG)

The set of preliminary simulations performed showed that the capability of removing the decay heat with a sufficient rate to prevent excessive peak cladding temperature increase depends on the ability of the cooling water (pumped through the cold legs) to reach the top of the core through alternative flow paths (steam generators).

Cold Leg Break Scenarios For smaller breaks (2"), the injection system is able to refill the steam generators with liquid water so that, at the time of core blockage, an alternative flow path is already available for the cooling water to reach to top of the core (from cold leg injection point, through the steam generators tubes and to the top of the core via hot legs).

For larger break sizes (6" and DEG), the break flow takes most of the cooling water coming from the two intact injection loops. The water injected through the cold leg preferentially moves in the downcomer toward the broken cold leg. The steam generators were found to be empty at the time of core blockage so no available alternative flow paths were observed for these cases. The core peak cladding temperature was found to diverge starting from the core blockage time. The simulations were stopped when the maximum limit of 800 OF was reached.

Hot Leg Break Scenarios Due to the break location compared to the loop injection location (cold leg) at the time to core blockage, the injected cooling water is forced to flow through the steam generators and reach the upper plenum before leaving the vessel through the broken hot leg.

For smaller breaks (2"), the available liquid inventory in the steam generators at the time of core blockage provides the coolant an alternative flow path to reach the top of the core and the observed peak cladding temperature increase appeared to be limited.

40

NOC-AE-1 5003220 Attachment 1 Enclosure For larger breaks (6" and DEG), some time is required for the cooling water to fill the steam generators and flow to the top of the core. During this period, the peak cladding temperature was found to increase but the maximum temperature reached after the core blockage time never exceeded the limit of 800 2F.

Figure 28, 29 and 30 show simple diagrams were the flow paths of the cooling water from the injection point (cold leg) to the top of the core are depicted.

Figure 28. Cooling Water Flow Paths (Small Break in Cold Leg) 41

NOC-AE-1 5003220 Attachment 1 Enclosure Figure 29. Cooling Water Flow Paths (Large Break in Cold Leg)

Figure 30. Cooling Water Flow Paths (Break in Hot Leg) 42

NOC-AE-1 5003220 Attachment 1 Enclosure Observing the peak cladding temperature profiles for the scenarios analyzed, common features can be identified:

1) At the time to core blockage, the peak cladding temperature was predicted to rapidly increase. This is essentially due to the rapid decrease in the core flow rate. Nevertheless, the final value of the temperature was found to be lower than the critical limit of 700 K in any scenario analyzed including the critical cases (medium and large breaks in cold leg). The simulations revealed that, as the water in the core reaches the saturation temperature, boiling helps removing the decay heat from the core. The vapor leaving the core is replaced by liquid water moving downward from the upper plenum to the core. This keeps the core cooled for a limited period of time.

2) In a later phase, for smaller breaks in cold leg or for all the hot leg scenarios analyzed, the ECCS water starts flowing through the steam generators, providing cooling water at the top of the core, and keeping the peak cladding temperature below the specified limit. For the failing cases (larger breaks in cold leg), this alternative flow of the cooling water is not available (may be established after the peak cladding temperature has reached the critical value), causing the peak cladding temperature to diverge.

4. ANALYSIS with 3D VESSEL - 3D CORE MODEL The medium break (6") in cold leg, which was found to be a critical case in the simulation performed with the 3D Vessel - 1D Core model, was selected to conduct further simulation with the use of the 3D Vessel - 3D Core model, described in section 2.2. The additional cases simulated are listed below:

1. Full Core + Core Bypass Blockage (same conditions as described in section 3).

2. Full Core Blockage + Free Core Bypass.

3. Core Bypass Blockage + Core Blockage except 1 Fuel Channel (Center).

4. Core Bypass Blockage + Core Blockage except 1 Fuel Channel (Periphery).

A preliminary simulation (1.) was performed with the same conditions applied to the analogous case performed with the 3D Vessel - 1D Core model, in order to confirm the results. Additional simulations were performed with a lower level of conservatism. In particular:

Case 2 was simulated to confirm the ability of the water to pass through the core bypass flow paths and reach the top of the core to provide the required cooling.

Cases 3 and 4 were simulated to verify whether the flow through one fuel channel (all the remaining 192 channels are assume to be fully blocked at the first restart after the sump switchover) is sufficient to provide the required cooling flow to maintain the peak cladding temperature under desired limits. These cases will also investigate any effect of the free fuel channel location in the core map. Figure 31 shows the location of the free fuel channel (marked in black) in the core map for the case 3 (left) and 4 (right).

43

NOC-AE-1 5003220 Attachment 1 Enclosure Figure 31. Free Channel Location. Case 3 (left), Case 4 (right).

Assuming the maximum peak cladding temperature as figure of merit, the scheme presented in Figure 32 summarizes the results of the simulations performed with the 3D Vessel - 3D Core model (pass/fail).

Confirmed 3D Vessel - ID Core Model Simulation Results I 1 2

Description Full Core + Bypass Blockage Full Core Blkag, Free Bypass Result

>1 3 Full Core Blockage except 1 FA (Center) 4 1 Full Core Blockae except 1 FA (Periphery)

Core Bypass (between Baffle and The coolant flow through one Fuel Barrel) may provide alternative flow Assembly (FA) was found to be path and allow decay heat removal enough to remove the decay heat Figure 32. 3D Vessel - 3D Core Model Simulations Summary Case 1 showed what was previously found using the 3D Vessel - 1D Core Model: the peak cladding temperature steadily increases reaching the maximum limit, confirming that the full core and core bypass blockage assumption imposed in this case may lead to core damage.

44

NOC-AE-1 5003220 Attachment 1 Enclosure Case 2 showed that the flow through the core bypass is sufficient to provide the required coolant flow at the top of the core and minimize the peak cladding temperature, even if the core is assumed to be fully blocked.

Case 3 and 4 predicted a sufficient flow through only one free fuel assembly to supply to required coolant flow and maintain the peak cladding temperature under the limit.

The peak cladding temperature for cases 1 to 4 is plotted in Figure 33.

8oo

-Case 1 750

-Case 2 700

-Case 3 a600 -Case 4

-Sump Switchover 550 L*500o

. ......Time to Core Blockage ES 400 350 300 -

3000 4000 5000 6000 7000 8000 Time [s]

Figure 33. 3D Vessel - 3D Core Model Simulations: Peak Cladding Temperature For cases 3 and 4, the coolant temperature at three different core elevations (inlet, midplane, and outlet) is plotted in Figure 34 and 35 respectively. These maps are snapshots taken after the time to core blockage.

45

NOC-AE-15003220 Attachment 1 Enclosure Ii5 Figure 34. Case 3: Coolant Cc)re Temperature Map: Inlet (left), middle (center), outle t (right). ['F]

4M Figure 35. Case 4: Coolant Core Temperature Map: Inlet (left), middle (center), outlet (right). [OF]

For case 3, the core flow rate maps are shown in Figures 36. The maps were taken at a give time after the sump switchover. Two views were provided: a horizontal cross section at the bottom of the core (Figure 36, top), and vertical cross section (Figure 36, bottom).

46

NOC-AE-1 5003220 Attachment 1 Enclosure 0

7 6

4 0

2 Figure 36. Core Mass Flow Rate (kg/s) Maps, Full Core Blocked except the Central Fuel Channel 47

NOC-AE-1 5003220 Attachment 1 Enclosure

5. REFERENCES

[1]. RELAP5-3D User's Manual, INEEL-EXT-98-00834

[2]. Texas A&M - RELAP5-3D Input Certification

[3]. Texas A&M - Sump Temperature Sensitivity Analysis 48

NOC-AE-15003220 Attachment 2 Attachment 2 Response to EMCB Request for Additional Information

NOC-AE-15003220 Attachment 2 Page 1 of 1 Mechanical and Civil Engineering Branch (EMCB)

2. In a letter dated December 13, 2013, the licensee explains that the strainers were analyzed for two load cases. Case 1 corresponds to the maximum temperature and a low differential pressure which occurs early following a loss-of-coolant accident, while debris loading is low. Case 2 corresponds to a maximum differential pressure, which occurs later when debris loading is at a maximum, and corresponds to a lower temperature. In both cases the interaction ratios are maintained below 1. However, it is unclear to the U.S.

Nuclear Regulatory Commission staff that these two load cases represent the most limiting loading conditions, and bound all other possible temperature and pressure combinations.

There could be a case where the differential pressure due to debris loading increases at a faster rate than the yield stress of the material increases due to the temperature drop.

Explain the basis for concluding that Case 1 and Case 2 are the bounding post-accident loading conditions for the strainers (i.e., they bound all other pressure and temperature combinations).

Response

To clarify the previous response:

" Case 1 corresponds to the maximum debris loading at the maximum temperature.

" Case 2 corresponds to the maximum debris loading at the minimum temperature.

Therefore, the analysis bounds all possible debris loading and temperature combinations.

NOC-AE-1 5003220 Attachment 3 Attachment 3 Response to ESGB Request for Additional Information

NOC-AE-15003220 Attachment 3 Page 1 of 10 STPNOC Round 2 RAIs - ESGB NOTES:

a. Round 2 RAI question numbers begin with the next sequential number from the April 15, 2014, RAI (Round 1 RAI) for the ESGB sections.

b. Follow-up questions from the STPNOC responses to the Round I RAI questions refer to the Round I RAI number for the ESGB sections.

c. In all cases, "Enclosure 1" refers to Enclosure I to Attachment 5, "Quantificationof Chemical Head Loss Epistemic Uncertainty;Basis for Incremental Chemical Head Loss Epistemic Uncertainty"contained in the licensee's letter dated July 15, 2014 (ADAMS Accession No. ML14202A045).

Chemical Effects

23. During the NRC staff audit in September 2014, representatives from STPNOC stated that the chemical effects evaluation model was being changed from the chemical "bump-up" factor multiplier discussed in the licensee's submittal dated November 13, 2013 (ADAMS Accession No. ML13323A190), to an alternate chemical model that uses an additive chemical head loss factor determined from the chemical loading term "L*." Assuming the bump-up factor approach is no longer being pursued, the NRC staff has reconsidered previous chemical effects related RAIs and determined that the following April 15, 2014, RAI questions are no longer relevant to the new chemical model: 1a-d, 3, 4, 5, 9, 17, and 18a-c. Please confirm that the staffs understanding is correct.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. Chemical effects are accounted for in the deterministic testing and the L* correlation is not used, nor is there a need to apply a factor to account for chemical effects. Consequently, the staff's conclusion is correct, albeit for a different reason.

24. The NRC staff has reviewed the overview of an alternate chemical effects approach contained in Enclosure 1 to Attachment 5, "Quantificationof Chemical Head Loss Epistemic Uncertainty;Basis for Incremental Chemical Head Loss Epistemic Uncertainty," contained in the licensee's letter dated July 15, 2014 (ADAMS Accession No. ML14202A045). This enclosure provides an overview of the alternate chemical effects method.

a. Please provide a detailed description of this chemical head loss model and its application to the STP plant-specific chemical effects analysis such that the NRC staff can perform a thorough review and evaluation.

NOC-AE-1 5003220 Attachment 3 Page 2 of 10

b. As part of the detailed description and based on CASA Grande realizations, please provide a histogram showing chemical head loss (feet) on the x-axis and number of occurrences on the y-axis for the medium-break LOCA (MBLOCA) and large-break (LBLOCA) categories. Please ensure the bin selections allow the NRC staff to discriminate different outcomes that result in acceptable head loss.

c. Please discuss whether the chemical head loss determined from the L* method is independent of the debris bed or in some way correlated with the debris bed.

d. Please describe in detail how the new chemical model will account for uncertainties. Some examples of uncertainties include: variability in chemical head loss behavior (e.g., an approximate 40 percent difference in head loss resulting from a change to the precipitate addition sequence in Enclosure 1, Figure 9), variability in head loss across different debris beds for the same type and quantity of precipitate, differences in corrosion/leaching behavior between test materials and plant materials, variability in temperature or pH compared to testing, other post-LOCA conditions (e.g., radiological) not present during testing.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. Chemical effects are accounted for in the deterministic testing and the L*correlation is not used, nor is there a need to apply a factor to account for chemical effects; thus, plant-specific testing accounts for the chemical head loss.

25. The NRC staff has several questions related to Figure 14 in the aforementioned Enclosure 1 to Attachment 5.

a. Given the head loss response to chemical precipitate addition shown earlier in Figures 1 and 2, it seems more appropriate to model head loss in a non-linear manner. Please discuss any plans to further develop the model.

b. The NRC staff is of the opinion that the 4 th "Bahn" data point placement in this plot is not appropriate given that the test loop was shut down at this point since the test loop head loss limit had been reached. Please discuss a plausible range of head loss for this test had it not been stopped and how that would affect the chemical head loss correlation.

c. Without consideration of item (b), the NRC staff calculated a greater chemical head loss (CHL) value (approximately 0.7 feet) when scaling a 13 feet of water result to the STP strainer test conditions according to Equation 2. Please provide a copy of the calculation showing the scaled value is approximately 0.4 feet.

NOC-AE-1 5003220 Attachment 3 Page 3 of 10

d. While the NRC staff agrees that comparison of chemical effects testing may provide insight, the relationship between flow and chemical head loss may be more complex than as shown by Equation 2. Please provide a basis for this scaling equation or discuss the limitations that may exist when extrapolating data over more than an order of magnitude in flow rates.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. Chemical effects are accounted for in the deterministic testing and the L* correlation is not used, nor is there a need to apply a factor to account for chemical effects; thus, plant-specific testing accounts for the chemical head loss.

26. Figure 25 in Enclosure 1 to Attachment 5 of letter dated July 15, 2014, shows new aluminum release equations that appear to be based on experiments run for Southern Nuclear Operating Company.

a. Please provide a copy of the Reference 17 (CHLE-SNC-005 Bench Test) Report that contains this data so that the NRC staff may understand how these tests were performed.

b. Confirm that the orange line in Figure 25 represents the 1600 series tests.

c. The aluminum release model appears to be predicting the same data as in Figure 24, which was used to develop the model. Please clarify if any additional data was used to develop the model.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. Chemical effects are accounted for in the deterministic testing and the L* correlation is not used, nor is there a need to apply a factor to account for chemical effects; thus, plant-specific testing accounts for the chemical head loss. RoverD does not rely on the test data from Southern Nuclear Company.

27. A limited release of aluminum during chemical effects testing is one of the key items STPNOC is relying on for concluding STP has relatively minor chemical effects. In ESGB

NOC-AE-1 5003220 Attachment 3 Page 4 of 10 question 13.b. of the April 15, 2014, RAI, the NRC staff asked if the two parts of scaffolding had been tested to compare their aluminum release. The licensee's response provided scanning electron microscope images along with energy dispersive spectroscopy (EDS) and x-ray photoelectron spectrometry (XPS) results.

Given that the two parts of scaffolding were used in different test conditions, that they were visually observed to have different texture and appearance, and that the Table 1 elemental compositions indicate potentially significant differences in key elements (e.g., Al, 0, P),

the NRC staff thinks it is important to verify that the corrosion behavior of the two scaffolding parts is similar. For example, one way to verify similitude would be to run a direct comparison of aluminum release in bench tests at higher post-LOCA temperatures to determine if the aluminum release was reasonably similar. Please provide a comparison of the corrosion behavior of the two parts of scaffolding.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. Chemical effects are accounted for in the plant-specific deterministic testing.

28. Since multiple tests suggest aluminum corrosion will be inhibited by phosphate after a relatively short time into the post-LOCA ECCS mission time, understanding the corrosion behavior of aluminum at elevated temperatures becomes very important. Recent aluminum corrosion testing by another licensee (see ADAMS Accession No. ML14184B509, Slide 18) showed that for their plant-specific conditions, significantly longer test durations at 195 degrees Fahrenheit (OF) did not release an equivalent quantity of aluminum as shorter time at higher temperatures. Please discuss the relevance of these results to the STP chemical effects approach for aluminum release at higher temperatures. Please include in that discussion the range of postulated plant-LOCA temperature profiles relative to the CHLE test MBLOCA and LBLOCA profiles and if any adjustments are needed to the aluminum release rates at temperatures greater than 185 OF.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. Chemical effects are accounted for in the plant-specific deterministic testing and STP no longer intends to apply a correlation to determine chemical effects.

NOC-AE-15003220 Attachment 3 Page 5 of 10

29. In Section 2.1.1 ("Zinc Phosphate") of Enclosure 1 to Attachment 5 of the licensee's letter dated July 15, 2014, the discussion states the following:

When zinc corrosion materials were included in the STP risk-informed tests, head loss response was observed during the initial hour of testing; however, additional tests indicated that the head loss response to the zinc product was likely the result of initial dissolution of a surface layer and not from transport of a continuously generated zinc corrosion product (Zn3(PO4)2°4 H20). Therefore, the initial zinc product release is treated as a particulate source and not considered a zinc chemical product.

Since Zn3(PO4)2°4 H20 is unlikely to transport to the strainer and, given that Option 1 CHL is intended to produce conservative or overestimated CHL response to identified precipitate loads, Zn3(PO4)2°4 H20 generation is ignored in the CHL correlation development.

Given the significant quantities of zinc present, the NRC staff finds it would be appropriate for a chemical model to account for zinc. Dissolution of galvanized steel or inorganic zinc coatings may occur at the lower pH before the trisodium phosphate (TSP) buffer fully dissolves to adjust the pH to an alkaline value. Dissolved zinc would then be available to react with the phosphate. In addition, some percentage of the galvanized surfaces could be susceptible to having zinc corrosion product knocked off by water falling from the pipe break, drains, etc. The NRC staff recognizes it may be appropriate to model zinc products separately from amorphous aluminum hydroxide type precipitates if warranted by the head loss response across a debris bed representative of a sump strainer bed. Please provide the quantity of zinc that is included in the "particulate source," how this amount of zinc affects head loss and if an additional zinc product should be included in the model.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. RoverD does not rely on a correlation or model to account for chemical effects. Chemical effects, including zinc, are accounted for in the plant-specific deterministic testing.

NOC-AE-15003220 Attachment 3 Page 6 of 10

30. Figure 21 in Enclosure 1 to Attachment 5 of the licensee's letter dated July 15, 2014, implies the WCAP-16530 release rate equations are being incorporated into CASA Grande which is not the case for aluminum. Please clarify which, if any, WCAP 16530-NP-A, "Evaluation of Post-Accident Chemical Effects in Containment Sump Fluids to Support GSI-191," March 2008 (ADAMS Accession No. ML081150379), release equations will be used with the alternate chemical head loss model approach.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. Chemical effects are accounted for in the plant-specific deterministic testing.

31. The chemical head loss is determined based on chemical precipitate loading per strainer (grams per meter square (g/m 2)). Please describe how the plant-specific incorporation of this model accounts for the greater chemical head loading for the cases where less than three trains operate following a LOCA.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. Chemical effects are accounted for in the plant-specific deterministic testing.

As described in Attachment 7, the testing was based on an assumption of two trains operating. In addition, RoverD evaluates the single-train case where the deterministic success criterion is half of the two train operating case debris.

NOC-AE-1 5003220 Attachment 3 Page 7 of 10

32. It is unclear to the NRC staff how STPNOC's response to ESGB question 14.a. of the April 15, 2014, RAI, evaluated the radiation effects on precipitates. Explain how uncertainties from the radiation effects on precipitate formation are considered in the STP chemical effects analysis.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. Chemical effects, including presumed radiation effects, are considered to be accounted for in the conservatism of plant-specific deterministic testing, which is performed per WCAP-16530. RAI responses in the NRC reviewed WCAP-16530-NP-A indicate that radiolysis and effects of radioactive species would not be expected to have a significant effect.

33. In the response to ESGB question 21 of the April 15, 2014, RAI, the mass of 24 pounds for a CRUD release following a LOCA is based upon the Electric Power Research Institute (EPRI) Boron-Induced Offset Anomaly estimates of fuel deposits that would affect a CRUD induced power shift (CIPS). While this may be an adequate prediction for CIPS susceptibility, it does not assess the total available transient CRUD layer in the primary coolant system. The fuel surface area is approximately 30 percent of available reactor coolant system (RCS) surface with other surfaces such as piping and Steam Generator tubing making up most of the remaining surface areas.

The EPRI Pressurized-Water Reactor (PWR) Primary Water Chemistry Guidelines state, in part:

Core flow transients should be minimized to minimize particulate entrainment which will increase dose rates and particulate contamination levels in low flow regions. Wall shear, which is approximately proportional to the square of the coolant velocity, is the primary factor promoting particulate releases subsequent to shutdown. A smooth transition to one pump operation is considered appropriate to reduce shear and minimize particulate releases during the shutdown transient.

During a reactor trip following a LOCA there is no "smooth transition" with liquid and gaseous flow plus solids entrainment. Thermal, hydraulic and chemical transients are all present, simultaneously. One of the most significant chemical changes is the presence of both hydrogen and oxygen in the water flowing to the sump as well as being recirculated back through the reactor core. This uncontrolled chemistry condition leads to both reductive and oxidative processes occurring simultaneously leading to particulate formation.

NOC-AE-1 5003220 Attachment 3 Page 8 of 10 The EPRI PWR Primary Water Chemistry Guidelines (Table 3-5 of Section 3.8) identifies analyses to be performed by Chemistry during a normal shutdown, including filterable and non-filterable: radioactive corrosion products, elemental nickel and iron. Therefore, the Chemistry department may have this information related to normal shutdowns and transient shutdowns.

Therefore, the NRC staff requests that the licensee determine if historical information is available concerning crud release from normal shutdowns and unplanned trips and to re-evaluate the crud release estimate based on any additional information, including release from all RCS sources during a LOCA.

Response

Historical information is available concerning CRUD release from pre-outage CRUD cleanup performance. CRUD release data during forced outages, including reactor trips, is bounded by CRUD burst cleanup data during refueling outages.

The outage release data pertain to releases following attempts to remove CRUD from surfaces using aggressive chemical cleaning products such as hydrogen peroxide to purposely remove as much CRUD as possible from the plant prior to outage work (primarily for ALARA interest).

The measurement of CRUD mass is based elemental analysis, not actual weight. The history of the weight of CRUD removed (using elemental analysis) from STP during outage CRUD removals is shown in the figure below. The CRUD measurements are consistent with industry practice for this performance indicator.

The figure shows the amount of Ni removed, not all metals. However, Ni is the predominant contributor to the CRUD inventory. The figure shows the total amount of CRUD removed during the crud burst evolution and cleanup.

The CRUD released is mostly soluble or very small particulate (< 1 micron) in size. Shown as well is the activity of Co58 which helps give an understanding of how much of the CRUD is coming from the fuel. STP further performs fuel ultrasonic cleaning which is an even more aggressive cleaning technique than chemical cleaning, removing substantial amounts of CRUD from reload fuel. This inventory reduction is not shown on the graph.

As the graph below shows, recent CRUD amounts are less than 2 lb such that CRUD is not a significant contributor to the debris inventory.

NOC-AE-15003220 Attachment 3 Page 9 of 10 South Texas Units I & 2 Outage Shutdown Crud Release Nickel and Cobalt 58 Comparisons Since Steam Generator Replacement 6000 14 12 5000 10 4000 I

3000 4

1000 2

0 1REIO 2REIO IREII 2REII1IRE12 2RE12 1RE13 2RE13 IRE14 2RE14 IREIS 2RE1C IREIC 2RE16 IRE17 IRElS 0ut"

• CNcbCd5$U -- *QwWt P*Ad

34. Please clarify the difference between the fiber amounts shown in the Table 2 and Figure 3 in Enclosure 1 of the licensee's letter dated July 15, 2014.

Response

Figure 3 shows weighted mean quantities determined for large breaks from a CASA Grande plant state Case. The CASA Grande quantities are based on a 17D ZOI. Table 2 shows tested strainer fiber quantities generated from a CAD model macro using a 7D ZOI from a specific location (Hot Leg).

Coatings

8. With respect to question 1 of the April 15, 2014, RAI, the response does not seem consistent with the current NRC staff position on debris characteristics for unqualified coatings. The testing you referenced is not applicable to unqualified coatings. This position is described in the NRC staff review guidance available at ADAMS Accession No. ML080230462. Please provide a revised analysis for the unqualified epoxy coatings in question.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. RoverD does not rely on a correlation or model to account for

NOC-AE-1 5003220 Attachment 3 Page 10 of 10 coatings. Note that Marinite has been removed from the STP containment buildings and the test included approximately 183 Ibm of powdered Marinite board which is almost twice the amount of epoxy introduced as chips. The Marinite can reasonably be considered to make up for the unqualified epoxy.

9. The licensee's response in question 2 of the April 15, 2014, RAI, stated that a Zone of Influence (ZOI) of 4D (4 Diameter) was used for inorganic zinc coatings. This position is inconsistent with the current NRC staff position. Based on the latest test data available the ZOI for inorganic zinc coatings should be 10D. A description of this position is available at ADAMS Accession No. ML100960495. Please provide a revised analysis for the ZOI of inorganic zinc coatings.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment

7) instead of using CASA Grande to generate conditional failure probabilities.

RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. RoverD does not rely on a correlation or model to account for coatings. Coatings are accounted for in the plant-specific deterministic testing. The quantity of inorganic zinc in the STP plant-specific testing was based on 5D ZOl.

10. With respect to question 6 of the April 15, 2014, RAI, the reductions credited for debris generated by unqualified coatings in upper containment is inconsistent with the current NRC staff position. Both the treatment of failure percentages and failure timing are based on EPRI testing that the staff has previously issued positions on. Staff guidance found at ADAMS Accession No. ML080230462 describes the staffs position with respect to this testing. In addition the NRC staff concerns regarding the failure timing being based on filter data (as described in the original questions 6b and 6c) are not adequately addressed by your responses. Please provide a revised analysis for the unqualified coatings in upper containment.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates to failure break sizes that generate and transport debris not bounded by deterministic testing. RoverD does not rely on a correlation or model to account for coatings. Coatings are accounted for in the plant-specific deterministic testing which does not rely on failure timing.

NOC-AE-15003220 Attachment 4 Attachment 4 Response to SCVB Request for Additional Information

NOC-AE-15003220 Attachment 4 Page 1 of 16 Containment and Ventilation Branch (SCVB)

NOTE: Round 2 RAI question numbers begin with the next sequential number from the April 15, 2014, RAI for this section.

10. Back-ground: The response to question 3.a of the April 15, 2014, RAI, does not appear to provide adequate justification for not revising the Updated Final Safety Analysis Report (UFSAR) description of the containment heat removal analysis. The response to question 3.c refers to a proposed UFSAR description of the risk assessment given in Enclosure 3, Attachment 2 of the licensee's letter dated November 13, 2013, which does not provide a revised licensing basis description of the containment heat removal analysis.

The licensee's response to question 4.a of the April 15, 2014, RAI, does not provide adequate justification for not revising the UFSAR description of the fission product removal analysis. The response to question 4c of the April 15, 2014, RAI, refers to a proposed UFSAR description of the risk assessment given in Enclosure 3, Attachment 2 of the licensee's letter dated November 13, 2013, which does not provide a revised licensing basis description of the revised fission product removal analysis.

Please refer to the following excerpt taken from the licensee's response to question 3.b of the April 15, 2014, RAI:

As described in the LAR, the proposed exemptions from General Design Criteria (GDC)-35, "Emergency Core Cooling", GDC-38, "Containment Heat Removal", and GDC-41, "Containment Atmosphere Cleanup" are for approval of a risk-informed approach for addressing GSI-191 and responding to Generic Letter (GL) 2004-02 for STP Units 1 and 2 as the pilot plants for other licensees pursuing a similar approach. As further described, STPNOC seeks NRC approval based on a determination that the risk informed approach and the risk associated with the postulated failure mechanisms due to GSI-191 concerns meets the guidance, key principles for risk-informed decision making, and the acceptance guidelines in RG 1.174.

STPNOC is not proposing to apply the risk-informed approach to revise the licensing basis for containment design described in the UFSAR. The proposed risk assessment evaluates a spectrum of Loss of Coolant Accident (LOCA) scenarios to quantify the amount of debris of various types that might be generated and transported to the emergency sumps, and how that debris might affect available NPSH [net positive suction head] for Emergency Core Cooling System (ECCS) and Containment Spray System (CSS) pumps taking suction from the sumps in the recirculation mode. It also evaluates potential transport of debris to the reactor core. It calculates failure probabilities that are fed to the STP PRA.

Concern: The staff agrees that the currently licensed design and configuration of the CSS and ECCS as described in the UFSAR will not be impacted by the risk-informed resolution to GSI-1 91 except for the change in the sump strainer design. However, the NRC staff is not in agreement that the UFSAR description of the licensing basis

NOC-AE-1 5003220 Attachment 4 Page 2 of 16 containment heat removal analysis, which uses CSS; the licensing basis containment fission product removal analysis, which also uses CSS; and the licensinq basis 10 CFR 50.46 analysis, which uses ECCS, will not be impacted by the risk-informed resolution to GSI-191. For breaks that produce less or no debris, the licensing basis analysis should be based on the deterministic approach without taking exemption from GDCs 35, 38, and 41. For breaks that produce large amount of debris and without taking exemptions from the GDCs (for example exemption from assuming single failure) it is not possible to meet the acceptance criteria for peak cladding temperature and containment heat and fission product removal, the risk-informed approach may be used and exemption from the GDCs may be requested for these specific breaks only.

The NRC staff has developed the flow chart shown in Figure 1 (on page 19 of this RAI) for defining the LOCA containment NPSH licensing basis analysis (which is the most significant part of containment heat removal analysis) for deterministic and risk-based GSI-191 resolution. The staff suggests the licensee to develop similar flow charts defining the deterministic and risk-based fission product removal and ECCS licensing basis analysis.

Question: RG 1.174 requires that the licensee should identify those aspects of the plant's licensing basis that may be affected by the proposed change, including but not limited to rules and regulations, UFSAR, technical specifications, licensing conditions, and licensing commitments. NUREG-0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants," (SRP) Chapter 19.2, "Review of Risk Information Used to Support Permanent Plant-specific Changes to the Licensing Basis:

General Guidance," Section I11.1 also requires that the changes in the plant licensing basis should be appropriately reflected in licensing documents such as technical specification (TSs), license conditions (LCs), and UFSAR. Therefore, the current licensing basis for the containment heat removal described in UFSAR Chapters 6 and 15 must be revised by including the description for the breaks for which partial or complete exemption from GDCs 35, 38, and 41 is requested.

(a) Provide UFSAR revisions of Chapters 6 and 15 for the description of revised licensing basis analysis of the containment heat removal for the breaks for which exemption from GDC-38 is requested.

(b) Provide UFSAR revisions of Chapter 6 for the description of revised licensing basis of the analysis of the containment spray system - iodine removal for the breaks for which exemption from GDC-41 is requested.

(c) Provide UFSAR revision of Section 6.3 for the description of revised licensing basis analysis of the ECCS for the breaks for which exemption from GDC-35 is requested.

Response (a), (b). (c):

STPNOC will add a reference to the UFSAR sections referenced above to provide a brief summary of the licensing basis and reference to the detailed description that will be provided in Appendix 6A to the UFSAR.

NOC-AE-15003220 Attachment 4 Page 3 of 16 The brief summary will be worded similar to the description below, using the appropriate function/GDC in the brackets:

The Licensing Basis for [containment heat removal] with regard to effects of debris on emergency sump strainers to the extent that the strainers support the [CSS or ECCS] element of the [containment heat removal function], is a risk-informed analysis that shows there is a high probability that [CSS or ECCS] can perform its design basis functions based on plant-specific prototypical testing using deterministic assumptions that provide safety margin and defense-in-depth and that the risk from breaks that could generate debris that is not bounded by the testing is very small in accordance with the criteria of RG 1.174.

The conservatism in the testing is significant enough that using realistic analysis and testing, it is not likely that debris effects on the strainer or on the core would result in fuel damage. In addition, the effects of debris do not compromise containment integrity which ensures defense in depth is preserved even in the unlikely event the core is compromised.

The STP Risk over Deterministic (RoverD) methodology was used to evaluate the effects of debris. RoverD relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure (core damage). It then applies the NUREG 1829 pipe break frequency for the smallest unbounded breaks to determine the increase in core damage frequency. The increase is compared to the criteria in RG 1.174. The analysis shows that the risk from the unbounded breaks is very small, as defined by RG 1.174. An exemption to [GDC 38] has been approved to allow application of the risk-informed analysis instead of the single failure assumption required by [GDC 38]. The exemption applies to the scope of breaks that generate and transport debris not bounded by the deterministic testing.

Details of the design basis for the effects of debris on the function of the emergency sump strainers is provided in UFSAR Appendix 6A.

STPNOC will revise the UFSAR Chapter 3 evaluations against Criteria 35, 38, and 41 (Planned changes are underlined):

3.1.2.4.6.1 Evaluation Against Criterion 35 - The ECCS is provided to cope with any LOCA in the plant design basis. Abundant cooling water is available in an emergency to transfer heat from the core at a rate sufficient to maintain the core in a coolable geometry and to assure that clad metal/water reaction is limited to less than 1 percent. Except for the effects of debris, adequate design provisions are made to assure performance of the required safety functions even with a single failure. The STP Risk over Deterministic (RoverD) methodology was used to evaluate the effects of debris. RoverD relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure (core damage). It then applies the NUREG 1829 pipe break frequency for the smallest unbounded breaks to determine the increase in core damage frequency. The increase is compared to the criteria in RG 1.174. The analysis shows that the risk

NOC-AE-1 5003220 Attachment 4 Page 4 of 16 from the unbounded breaks is very small, as defined by RG 1.174. An exemption to GDC 35 has been approved to allow application of the risk-informed analysis instead of the single failure assumption required by GDC

35. The exemption applies to the scope of breaks that generate and transport debris not bounded by the deterministic testing. Details of the conditions for the exemption are included in Appendix 6A.

Details of the capability of the systems are included in Section 6.3. An evaluation of the adequacy of the system functions is included in Chapter

15. Performance evaluations have been conducted in accordance with 10CFR50.46 and 10CFR50 Appendix K.

3.1.2.4.9.1 Evaluation Against Criterion 38 - The CHRS consists of the CSS, the Reactor Containment Fan Cooler (RCFC) Subsystem and the residual heat removal (RHR) heat exchangers. The CHRS acts in conjunction with the Safety Injection System to remove heat from the Containment. The CHRS is designed to accomplish the following functions in the unlikely event of a LOCA: to rapidly condense the steam within the Containment in order to prevent over pressurization during blowdown of the RCS; and to provide long-term continuous heat removal from the Containment.

Initially, the CSS and the high-and low-head safety injection (HHSI and LHSI) pumps take suction from the refueling water storage tank (RWST).

During the recirculation phase, the CSS and the HHSI and LHSI pumps take suction from the Containment emergency sumps. The CHRS is divided into three trains. Each train is sized to remove 50 percent of the system design heat load at the start of recirculation. Each train of the CHRS is supplied power from a separate independent Class 1E bus. The redundancy and capability of the Offsite and Emergency Power Systems are presented in the evaluation against Criterion 17. Redundant system trains and emergency diesel power supplies provide assurance that system safety functions can be accomplished. An exemption to GDC 38 has been approved to allow application of a risk-informed analysis instead of the single failure assumption required by GDC 38, to address the effects of debris. The STP Risk over Deterministic (RoverD) methodology was used to evaluate the effects of debris. RoverD relegates break sizes that aenerate and transport debris that is not bounded by deterministic testing to failure (core damage). It then applies the NUREG 1829 pipe break frequency for the smallest unbounded breaks to determine the increase in core damaae frequency. The increase is compared to the criteria in RG 1.174. The analysis shows that the risk from the unbounded breaks is very small, as defined by RG 1.174. The exemption applies to the scope of breaks that generate and transport debris not bounded by the deterministic testing. Details of the conditions for the exemption are included in Appendix 6A.

For further discussion, see the following sections of the UFSAR:

Residual Heat Removal System 5.4.7 Design for Debris Effects App. 6A Containment Systems 6.2

NOC-AE-15003220 Attachment 4 Page 5 of 16 Engineered Safety Features Actuation System 7.3 Onsite Power System 8.3 Accident Analysis 15.0 3.1.2.4.12.1 Evaluation Against Criterion 41 - The CSS is provided to reduce the concentration and quantity of fission products in the Containment atmosphere following a LOCA. Per IOCFR50.44, hydrogen recombiners are no longer required for design basis accidents.

The equilibrium sump pH is maintained by trisodium phosphate (TSP) contained in baskets on the containment floor. The initial CSS water and spilled RCS water dissolves the TSP into the containment sump allowing recirculation of the alkaline fluid. Each unit is equipped with three 50-percent spray trains taking suction from the Containment sump. Each Containment spray train is supplied power from a separate bus. Each bus is connected to both the Offsite and the Standby Power Supply Systems.

This assures that for Onsite or for Offsite Electrical Power System failure, their safety function (except for the consideration of debris effects) can be accomplished, assuming a single failure. An exemption to GDC 41 has been approved to allow application of a risk-informed analysis instead of the single failure assumption required by GDC 41. to address the effects of debris on the CSS function. The STP Risk over Deterministic (RoverD) methodology was used to evaluate the effects of debris. RoverD relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure (core damage). It then applies the NUREG 1829 pipe break frequency for the unbounded breaks to determine the increase in core damage frequency. The increase is compared to the criteria in RG 1.174. The analysis shows that the risk from the unbounded breaks is very small, as defined by RG 1.174. The exemption applies to the scope of breaks that generate and transport debris not bounded by the deterministic testing. Details of the conditions for the exemption are included in Appendix 6A.

Post-accident combustible gas control is assured by the use of the Supplementary Containment Purge Subsystem.

For further discussion, see the following sections of the UFSAR:

Containment Systems 6.2 Containment Spray System - Iodine Removal 6.5.2 Design for Debris Effects App. 6A Containment Hydrogen Sampling System 7.6.5 Containment HVAC System 9.4.5

11. Please note that the use of risk-based approach for resolution of GSI-1 91 requires a change in the licensing basis for the CSS operating in the presence of debris. RG 1.174 describes an acceptable approach for assessing the nature and impact of proposed licensing basis changes. This RG requires that the licensee should identify all SSCs,

NOC-AE-15003220 Attachment 4 Page 6 of 16 procedures, and activities that are covered by the licensing basis change being evaluated.

The response to question 1.a of the April 15, 2014, RAI, states that the CSS is the only system for which the exemption from GDC-38 is requested. Note that the CSS has associated supporting systems such as the safety-related electrical, Emergency Diesel Generator (EDG), instrumentation and control (W&C), and cooling water systems.

Therefore, as required by RG 1.174, please identify all the associated SSCs, procedures and activities that support the operation of the CSS for containment heat removal in the presence of debris.

Response

Per STP UFSAR Chapter 3.1.2.4.9.1, GDC 38 is met by RCFC working in conjunction with CSS and ECCS (LHSI through the RHR heat exchangers) to remove heat from the containment. The scope of the exemption will apply also to the ECCS because of its reliance on the sump strainers. Only the CSS and the ECCS functions are directly affected by debris since they are the containment heat removal functions that rely on the sump strainers in the recirculation phase.

No exemption is proposed to apply to the support systems for the CSS or the ECCS. The proposed exemptions apply only for the effects of debris.

None of the CSS or ECCS support systems rely on the ECCS emergency sumps and strainers to perform their support function and thus will not be affected by debris.

SCVB-RAI- 12

12. The response to question 1.b of the April 15, 2014, RAI, does not state which requirements of GDC-38 will not be met. The key GDC-38 requirements to be met for the CSS system design, concurrent with functioning of associated systems are as follows:

(1) Perform the safety function of containment heat removal, and rapidly reduce the containment pressure and temperature and maintain them at acceptably low level.

Response

STPNOC proposes that the exemption would apply for this requirement for those LOCA breaks that could generate an amount of debris that is not bounded by the deterministic testing. Current STP design basis calculations are based on RCFC functioning in conjunction with CSS and ECCS, which can be affected by debris.

NOC-AE-1 5003220 Attachment 4 Page 7 of 16 (2) Safety function (1) shall be performed following any LOCA

Response

Using current deterministic assumptions, STPNOC's analysis and testing does not assure that the emergency sump strainers will be available to support the CSS and ECCS function for the effects of debris produced by LOCA breaks that can generate debris that is not bounded by plant-specific deterministic testing, as described in RoverD.

(3) Safety function (1) shall be performed in the presence or absence of Loss of Offsite Power (LOOP).

Response

STP does not propose an exemption to this requirement. Debris affects only the function of the emergency sump strainers which do not perform any support function for emergency power for CSS or ECCS in the event of a LOOP.

(4) Safety function (1) shall be performed in the presence of a worst single failure.

Response

The STP application requested exemption to this requirement in order to allow a risk-informed methodology in lieu of the deterministic worst single failure required by the GDC. In accordance with the single failure criteria, a single occurrence that causes multiple failures is considered a single failure.

The effects of debris for the breaks described in (2) above are analyzed to affect all three emergency sump strainers. STPNOC requests exemption to this requirement for the debris effects from LOCA breaks that can generate debris that is not bounded by deterministic testing to allow the application of a risk-informed analysis that shows that the risk from debris effects is very low, in accordance with the RG 1.174 criteria, as described in RoverD.

NOC-AE-15003220 Attachment 4 Page 8 of 16 Note that requirement (2) covers all postulated LOCAs of any break size, including the most limiting from debris generation, containment peak pressure, and containment peak temperature standpoint.

Please provide the following information:

a. Is full exemption from the GDC-38 requirements (2), (3), and (4) requested? If so, irrespective of the break size, break location, or quantity of debris generation, all CSS trains along with their supporting system may be used. Please provide justification for the proposal of a full exemption from these requirements.

Response

The STPNOC application specifically requests exemption to Item (4), which has a direct link to Items (1) and (2). No exemption to Item (3), LOOP, is needed.

b. Is a partial exemption from GDC-38 requirement (2) requested (i.e., for specific LOCAs only and full exemption from requirements (3) and (4))? If so, specify the LOCAs in terms of location, break size, and debris generation rate for which the exemption is requested from meeting requirement # (3) and (4), and provide justification for the exemption request.

Response

The scope of the exemption applies for LOCA break sizes and locations that potentially generate debris that exceeds the quantity bounded by STP plant-specific testing. That scope is generally described as breaks larger than approximately 12.8" ID in locations where a sufficient amount of fibrous debris can be generated and transported to the sump. Forty-five (45) weld locations have currently been identified on the pressurizer surge line and RCS main loop piping. To minimize the potential that a later analysis could cause the specific locations to change, the requested exemption is based on the break's ability to generate sufficient transportable debris, as described in RoverD.

The basis for the exemption is described in the response to the first RAI above.

NOC-AE-1 5003220 Attachment 4 Page 9 of 16

13. The response to question 2.a of the April 15, 2014, RAI, states that the CSS is the only system for which the exemption from GDC-41 is requested. Note that the CSS also has associated supporting systems to which GDC-41 may apply. Please list all the associated systems that support the operation of the CSS; such as the safety-related electrical, EDG, I&C, and cooling water systems. Therefore as required by RG 1.174, please identify all the associated SSCs, procedures and activities that support the operation of the CSS for fission product removal in the presence of debris.

Response

No exemption is proposed to apply to the support systems for the CSS. The proposed exemptions apply only for the effects of debris. None of the CSS support systems rely on the ECCS emergency sumps and strainers to perform their support function and thus will not be affected by debris.

14. The response to question 2.b of the April 15, 2014, RAI, does not state which requirements of GDC-41 will not be met. The key GDC-41 requirements to be met for the CSS system design, concurrent with functioning of associated systems are as follows:

(1) Please list systems required to perform the safety function of controlling fission products, hydrogen, oxygen, and other substances that may be released into the reactor containment to reduce, consistent with the functioning of other associated systems, the concentration and quality of fission products released to the environment and to control the concentration of hydrogen and oxygen and other substances in the containment atmosphere to assure that containment integrity is maintained.

Response

No exemption is proposed to apply to the support systems for the CSS. The proposed exemptions apply only for the effects of debris. None of the CSS support systems rely on the ECCS emergency sumps and strainers to perform their support function and thus will not be affected by debris.

(2) Safety function (1) shall be performed followinq all postulated accidents.

Response

Using deterministic assumptions, STPNOC's analysis and testing does not assure that the emergency sump strainers will be available to support the CSS function for the effects of debris produced by LOCA breaks that can generate debris that is not bounded by plant-specific deterministic testing, as described in RoverD.

NOC-AE-1 5003220 Attachment 4 Page 10 of 16 (3) Safety function (1) shall be performed by providing suitable redundancy in components and features, suitable interconnections, leak detection and isolation, and containment capabilities.

Response

STPNOC does not propose exemption to this requirement since these functions are not affected by debris.

(4) Safety function (1) shall be performed in the presence or absence of LOOP.

Response

STPNOC does not propose an exemption to this requirement. Debris affects only the function of the emergency sump strainers which do not perform any support function for emergency power for CSS in the event of a LOOP.

(5) Safety function (1) shall be performed in the presence of a worst single failure.

Response

The STPNOC application requested exemption to this requirement in order to allow a risk-informed methodology in lieu of the deterministic worst single failure required by the GDC. In accordance with the single failure criteria, a single occurrence that causes multiple failures is considered a single failure.

The effects of debris for the breaks described in (2) above are analyzed to affect all three emergency sump strainers. STPNOC requests exemption to this requirement to allow the application of a risk-informed analysis that shows that the risk from debris effects is very low, in accordance with the RG 1.174 criteria.

(a) Is full exemption from the GDC-41 requirements (2), (3), (4), and (5) requested?

If so, than irrespective of the break size, break location, or quantity of debris generation, all CSS trains along with their supporting system may be used.

Please provide justification for the proposal of a full exemption from these requirements.

Response: See response to (b) below.

NOC-AE-15003220 Attachment 4 Page 11 of 16 (b) Is a partial exemption from GDC-41 requirement (2) requested (i.e., for specific LOCAs only, and full exemption from requirements (3), (4), and (5))? If so, specify the LOCAs in terms of location, break size, and debris generation rate for which the exemption is requested from meeting requirements (3), (4), and (5),

and provide justification for the exemption request.

Response

STPNOC requests partial exemption; i.e., only Item 2 above. As stated above, STPNOC's analysis and testing does not assure that the emergency sump strainers will be available to support the CSS function for the effects of debris produced by LOCAs that generate and transport debris that is not bounded by testing, as described in RoverD. Forty-five (45) weld locations have currently been identified on the pressurizer surge line and RCS main loop piping. To minimize the potential that a later analysis could cause the specific locations to change, the requested exemption is based on the break's ability to generate sufficient transportable debris, as described in RoverD.

15. The response to question 9.a of the April 15, 2014, RAI, states that the ECCS is the only system for which the exemption from GDC-35 is requested. Please note that the ECCS whose subsystems are High Head Safety Injection (HHSI) and the Low Head Safety Injection (LHSI) systems are not the only ones for which the proposed exemption to GDC-35 would apply. List all of the supporting system that support the operation of the HHSI and LHSI subsystems; for example the safety-related electrical, EDG, I&C, and cooling water systems. Therefore as required by RG 1.174, please identify all the associated SSCs, procedures and activities that support the operation of the HHSI and LHSI systems in the presence of debris.

Response

No exemption is needed for systems that support ECCS. The debris affects only systems that rely on the emergency sump strainers as a support system. None of the support systems required for ECCS operability such as cooling water, instrumentation and control, and normal and emergency power rely on the emergency sump strainers to perform their function. The requested exemption for GDC 35 the ECCS support systems (And the requested exemptions for GDC 38 and 41 do not apply to the CSS support systems.)

NOC-AE-15003220 Attachment 4 Page 12 of 16

16. The response to question 9b of the April 15, 2014, RAI, does not state which requirements of GDC-35 will not be met. The key GDC-35 requirements to be met for the ECCS design, concurrent with functioning of associated systems are as follows:

(1) Perform the safety function of transferring heat from reactor core at a rate such that (a) fuel and clad damage that could interfere with continued effective core cooling is prevented and (b) clad metal-water reactor is limited to negligible amounts.

Response

The STPNOC proposed exemption would apply for this functional requirement. As discussed in prior responses and described in the RoverD methodology, the function of the ECCS emergency sump is assumed to fail for debris that exceeds the amount in the deterministic testing. Under these assumptions, failure of the sump and strainers will result in loss of cooling to the core.

(2) Safety function (1) shall be performed following any LOCA.

Response

STPNOC's analysis and testing does not assure that the emergency sump strainers will be available to support the ECCS function for the effects of debris produced by LOCAs that generate and transport debris that is not bounded by testing, as described in RoverD. Consequently, STPNOC is requesting exemption for that scope of LOCAs that will produce and transport sufficient debris to exceed the debris forming the basis for the deterministic testing described in RoverD.

(3) Safety function (1) shall be performed by providing suitable redundancy in components and features, suitable interconnections, leak detection and isolation, and containment capabilities.

Response

STPNOC does not propose exemption to this requirement since these ECCS support functions are not affected by debris.

(4) Safety function (1) shall be performed in the presence or absence of LOOP.

Response

STPNOC does not propose an exemption to this requirement. Debris affects only the function of the emergency sump strainers which do not perform any support function for emergency power for ECCS in the event of a LOOP.

NOC-AE-1 5003220 Attachment 4 Page 13 of 16 (5) Safety function (1) shall be performed in the presence of a worst single failure.

Response

The STPNOC application requested exemption to this requirement in order to allow a risk-informed methodology in lieu of the deterministic worst single failure required by the GDC. In accordance with the single failure criteria, a single occurrence that causes multiple failures is considered a single failure.

The effects of debris for the breaks described in (2) above are analyzed to affect all three emergency sump strainers. STPNOC requests exemption to this requirement for the debris effects from LOCA breaks that can generate debris that is not bounded by deterministic testing to allow the application of a risk-informed analysis that shows that the risk from debris effects is very low, in accordance with the RG 1.174 criteria, as described in RoverD.

Note that requirement (2) covers all postulated LOCAs of any break size, including the most limiting from debris generation or peak clad temperature standpoint. Please provide the following information:

(a) Is full exemption from the GDC-35 requirements (2), (3), (4), and (5) requested?

If so, irrespective of the break size, break location, or quantity of debris generation, all ECCS trains along with their supporting system may be used for performing safety function (1). Please provide justification for requesting a full exemption from these requirements.

Response: See response to (b).

(b) Is a partial exemption from GDC-35 requirement (2) requested (i.e., for specific LOCAs only and full exemption from requirements (3), (4), and (5))? If so, specify the LOCAs in terms of location, break size, and debris generation rate for which the exemption is requested from meeting requirement # (3), (4), and (5),

and provide justification for the exemption request.

Response

STPNOC is requesting a partial exemption as discussed in the responses above. The proposed exemption to GDC 35 would apply to Items (1), (2), and (5) for the scope of breaks described in (2). The technical basis is described in the RoverD methodology (Attachment 7).

NOC-AE-1 5003220 Attachment 4 Page 14 of 16

17. In question 7 of the April 15, 2014, RAI, the NRC staff requested the licensee to provide the equivalent of UFSAR Section 6.2.1.5, which should describe the licensing basis of the minimum containment pressure analysis for performance capability of ECCS in the presence of debris for the risk-based analysis. Successful functioning of the LHSI, HHSI systems and the CSS in the presence of debris requires exemption from GDC-35 and GDC-38. Therefore, in the presence of debris during LOCAs, the description of the minimum containment pressure analysis for performance capability should be different from what is described in the UFSAR Section 6.2.1.5. The licensee's response to question 7 did not describe the proposed containment analysis, including assumptions and inputs, performed for the calculation of minimum containment pressure input for the ECCS analysis that calculates the peak cladding temperature for risk-informed GSI-191.

Please justify that the inputs and assumptions are conservative for the purpose.

Response

STP will respond to this RAI in a separate submittal.

NOC-AE-15003220 Attachment 4 Page 15 of 16

18. Please provide the following additional information with respect to your response to question 3.b of the April 15, 2014, RAI:

(a) Refer to the table on page 9 of Attachment 3 to the licensee's letter dated June 25, 2014 (ADAMS Accession No. ML14178A481), of major qualitative differences, for the subject "Sump Pool Treatment," please explain what is meant by: "No decay heat added. Mass and energy subtracted from the pool based on RELAP5-3D instructions."

(b) Refer to the table referenced in item a) for the subject "Pipe break mass/energy source," please explain what is meant by: "Communicated from RELAP5-3D via coupling interface as problem time progresses. The source is split by MELCOR into part liquid water, part steam, and part 'fog'."

(c) Refer to the table under the heading "Summary Comparison of Main Parameter Values," on page 10 of Attachment 3 to the licensee's letter dated June 25, 2014, please provide the basis for selecting the RELAP-3D/MELCOR values of the parameters in the table below and how are they determined:

RELAP-3D/MELCOR VALUE Initial atmosphere temperature 119.93 °F Initial containment pressure 14.94 psia Initial relative humidity, partial pressure of water vapor 70%/ 1,184 psia Initial RWST temperature 85 OF Spray actuation times 15 s delay after setpoint, linear ramp to full flow Fan cooler actuation times 15 s delay after setpoint (d) Refer to the table referenced in item c) for the CONTEMPT and RELAP-3D/MELCOR analysis, please provide the basis for using different values of (1) thermal conductivity of concrete, (2) thermal conductivity of stainless steel, (3) specific heat capacity of concrete, (4) specific heat capacity of stainless steel, and (5) density of stainless steel.

Response (a), (b), (c), (d):

The RoverD methodology does not use RELAP5-3D or MELCOR for containment conditions.

NOC-AE-1 5003220 Attachment 4 Page 16 of 16 A shall be the licensing basis analysis for the entire break spectrum using deterministic approach Using DETERMINISTIC APPROACH perform conservative LOCA NPSH analysis for the entire break spectrum considering debris (Notes I & 5)

NPSHA > I PSHR*,r (Note I

I NPSHA < NPSHRKI K] Acronyms CAP CDF GDC HI Containment accident pressure Core damage frequency General Design Criterion Hydraulic Institute (Note 3) LERF Large early release frequency KB Perform conservative LOCA NPSH LOCA Loss of coolant accident LOOP Loss of offsite power analysis without debris for breaks in NPSH Net positive suction which NPSHA < NPSHReff in A (Note head 5). NPSHA NPSH available No PHNPSHA < NPSHR NPSHRIr 'NPSH required' licensing I PRA including uncertainty Probabilistic Risk basis I

-T NPSHA > NPSHRff (Note 4)

Assessment NPSHA < NPSHR3%,,

rbUse PRA APPROACH for breaks analyzed in B.

Notes

1. Analysis shall be in compliance with GDC-I Perform realistic Perform realistic LOCA NPSH 38

2. Criteria shall be satisfied for the entire break spectrum considering debris.

3. Criterion is satisfied for some breaks cases considering debris.

analysis for break cases analyzed in 4. Criteria shall be satisfied for all break LOCA NPSH analysis for debris B while considering debris (Note 6). Id cases analyzed without considering debris.

break cases in C in 5. Conservative LOCA NPSH analysis shall NPSHA < NPSHR,.

which NPSHA < (Note 3) be based on conservative input NPSHR,%. assuming parameters and assumptions to minimize no single failure &

no LOOP.

- NPSHA while assuming single failure and LOOP.

"- NPSHA >NPSHRy 3

6. Realistic LOCA NPSH analysis shall be (Notes 3 & 10) based on nominal input parameters and I

assumptions while assuming single failure and LOOP.

NPSHA > NPSHR, 7. HI definition of NPSHR 3%is the NPSH (Note II) corresponding to a decrease in the pump total dynamic head of 3% for a given flow.

8. NPSHRe, = NPSHRS% + Uncertainty

9. CAP guidance in ADAMS document I Verify if ACDF and ALERF are acceptable + other requirements ML13015A437 shall be followed for determining uncertainty.

10. Partial exemption from GDC-38 is required (because of not meeting the requirement for entire break spectrum with debris) for break cases analyzed in C that meet Not acceptable No NPSHA > NPSHR3%.

licensing 11. Partial exemption from GDC-38 is required basis (because of not meeting the single failure Accepta able criteria, LOOP, and the entire break spectrum with debris) for breaks cases IT analyzed in D

• C shall be the licensing basis for breaks analyzed in C in which NPSHA > NPSHR3%.using PRA approach.

D shall be the licensing basis for breaks analyzed in D in which NPSHA a NPSHR3O/ using PRA approach.

A shall be the licensing basis for breaks analyzed in A in which NPSHA > NPSHRe, using deterministic approach.

FIGURE 1: Flow Chart for Defining the LOCA Containment NPSH Licensing Basis Analysis for Deterministic and Risk-Based GSI-191 Resolution

NOC-AE-1 5003220 Attachment 5 Attachment 5 Response to SSIB Request for Additional Information

NOC-AE-15003220 Attachment 5 Page 1 of 40 SSIB Round 2 RAIs NOTES:

a. Round 2 RAI question numbers begin with the next sequentialnumber from the April 15, 2014, RAI (Round 1) for this section.

b. Follow-up questions from the STPNOC responses to the Round 1 RAI questions refer back to the Round I RAI number from this section unless otherwise specified.

43. In question 2 of the April 15, 2014, RAI, the licensee stated that the values for size distributions for the fibrous insulation are documented in Reference 46. Reference 46 was not included in the submittal. Please provide a summary of the relevant size information from Reference 46 in the form of a table including the size distributions within the postulated ZOls.

Response

An application was made to withhold this information from public inspection as part of a letter dated May 15, 2014 (ADAMS Accession No. ML14149A353) as it appeared in CASA Grande input files that were submitted to the NRC for review. Permission to withhold the document pursuant to 10 CFR 2.390(b)(5) and Section 103(b) of the Atomic Energy Act of 1954, as amended, was granted on ML14092A557 dated June 4, 2014. As such, Reference 46, was and is, respectfully not included in the submittal.

The methodology used by STPNOC (LAR Encl. 4-3 Rev.2) for size distributions of LDFG (% of each size category) destroyed by a postulated ZOI, has been previously reviewed by the NRC in the 'Indian Point Energy Center Corrective Actions for Generic Letter 2004-2' document (i.). In the Indian Point Energy Center Corrective Actions document, NRC reviewers stated 'The staff found this approach for Nukon and Temp-Mat TM to be acceptable because it is consistent with or more precise than the DDTS evaluations,' when discussing the methodology used for size distributions of LDFG generated within the ZOI; this same methodology was implemented for STP.

i. MML082050433. "Indian Point Energy Center Corrective Actions for Generic Letter 2004-02," 2008.

44. In question 4 of the April 15, 2014, RAI, that NRC staffs review indicates that it is likely that the STP methodology discussed in the response may be acceptable and may provide conservative transport results when considered within the probabilistic framework.

However, low density fiberglass (LDFG) congestion may not be the metric that dominates the likelihood of debris reaching the strainer based on break location. Although the use of the steam generator compartment transport fraction may be moderately conservative as claimed, the NRC staff was unable to verify this assumption. It was also not clear to the staff that the measure of fiber congestion within specifically defined volumes in

NOC-AE-15003220 Attachment 5 Page 2 of 40 containment provide the most important measure of debris amounts that may be generated or the probability that debris would be generated within those volumes. If one location is congested, but the fibrous debris in that area cannot be damaged by a break it is not relevant. Please verify that the methodology results in overall realistic or conservative transport fractions considering the possible break locations and the LDFG congestion.

Response

The methodology used to estimate the transport of fibrous debris from all potential break locations is realistic and conservative, as shown in the discussion that follows.

Table 2 of Round 1, SSIB-111-4 Response illustrates a metric of LDFG congestion percent for each break category. This congestion metric (Round 1, SSIB-111-4 Response) was a supplemental metric to support the implementation of the steam generator transport fraction for all breaks in LAR Encl. 4-3. The congestion metric was not used to determine the debris transport to the strainer (referred to as transport fractions). In essence, LDFG congestion may not be the metric that dominates the likelihood of debris reaching the strainer based on break location, and in Round 1, SSIB-llI-4, response it was intended as a secondary, supplemental observation.

Table 1 below, (also Table I of Round 1, SSIB-III-4) illustrates the total transport fractions from the five large break scenarios examined in the debris transport calculation (i, Section 6.0, Table 6.0.8-6.0.13, Pg. 159-164). Note that these are the results of the maximum total transport values.

Table 1: Overall Debris Transport Fractions Break Location Individual Region LDFG Small LDFG Large LDFG Latent SG Compartment 99% 42% 1% 95%

Below SG 99% 60% 7% 95%

Compartment Pressurizer 97% 31% 1% 91%

Compartment Pressurizer Surge 97% 30% 1% 91%

Line RHR Compartment 97% 30% 2% 91%

Annulus 97% 33% 8% 91%

With the sole exception of breaks occurring below the SG Compartment, the overall transport fractions associated with Individual LDFG and Small LDFG for breaks in the SG Compartment are equal to or greater than the overall transport fractions associated with Individual LDFG and Small LDFG for other break locations. At first glance, this may imply that using overall transport fractions associated with breaks in the SG Compartment for breaks that occur below the SG Compartment for Individual LDFG and Small LDFG would yield an un-conservative assessment of the effects, e.g., strainer headloss, of breaks that occur below the SG Compartment. However, only

NOC-AE-1 5003220 Attachment 5 Page 3 of 40 278 ft3 of LDFG exists below the SG Compartment (iii.). Even if all LDFG below the SG Compartment failed and transported, i.e., the overall transport fraction was 1.0, there would not be enough debris to cause failure in a full risk-informed evaluation, (see SSIB-45f Table 3 which gives the minimum amount of fiber generated that causes a CASA Grande scenario to go to failure of 325 ft 3 for the all pumps active base Case 1). Therefore, using an apparently non-conservative overall transport fraction for breaks occurring below the SG Compartment is of no practical relevance. On the other hand, using overall transport fractions for Individual LDFG and Small LDFG associated with breaks in the SG Compartment for all break locations is conservative because (1) the transport fractions for Individual LDFG and Small LDFG for breaks in the SG Compartment were conservatively derived, and (2), transport fractions for Individual fine fiber LDFG and Small LDFG for breaks in the SG Compartment exceed those associated with other break locations; see Table 1.

Table 1 shows that transport fractions for Large Fiber associated with breaks in the RHR Compartment and Annulus exceed the transport fraction for Large Fiber associated with breaks in the SG Compartment. However, the maximum total fiber, including all sizes, associated with the breaks in the RHR Compartment and Annulus are 299.4 ft 3 and 79.4 ft3, respectively.

Similar to the case above for breaks that occur below the SG Compartment, even if all LDFG associated with the breaks in the RHR Compartment and Annulus failed and transported, i.e., the overall transport fraction was 1.0, there would not be enough debris to cause failure in a full risk-informed evaluation. Therefore, using an apparently non-conservative overall transport fraction for breaks occurring in the RHR Compartment and Annulus is of no practical relevance.

In conclusion, using transport fractions associated with breaks in the SG Compartment for breaks in all regions of containment results in adequate and conservative estimates of transport for all cases where the acceptance criteria for sump headloss may be challenged.

The following discussion illustrates that the methodology used to determine transport fractions resulted in realistic and conservative transport fractions.

The debris transport fractions were calculated in LAR Encl. 4-3, Reference

23. As stated in the responses to Round 1 RAIs, this calculation was revised to Revision 3 (i.) which is summarized below while highlighting conservatisms and assumptions.

Debris transport is the estimation of the fraction of debris that is transported from debris sources (break locations) to the sump strainers. Since risk-informed methodology examines numerous welds in containment, the transport fractions are determined as a function of break location as specified below.

• Breaks in the steam generator compartments

• Breaks in the reactor cavity

• Breaks inside secondary shield wall (ISSW) beneath steam generator compartments

• Breaks in the pressurizer compartment

NOC-AE-1 5003220 Attachment 5 Page 4 of 40

• Breaks outside secondary shield wall in the pressurizer surge line

" Breaks outside secondary shield wall in the residual head removal (RHR) compartments

• Breaks outside secondary shield wall in the annulus Debris transport is subdivided into five modes or phases which are:

Blowdown transport- the transport of debris by the break jet. As stated in the Round 2, SSIB-lII-6a response, blowdown does not capture debris (or reduce the amount of debris available for transport). Blowdown estimates the location of debris while accounting for obstructions that cause debris to be retained in the compartment of break origin. This blowdown phenomenon is referred to as "capture" in this RAI, but it does not reduce the amount of debris available for transport in subsequent transport modes.

o Blowdown was independently determined for each break location due to the variance of the flow obstructions.

o Blowdown transports debris to upper containment, the containment pool, and debris retained in the compartment of break origin which is calculated by:

" Transport to upper containment - the volume ratio of upper containment to all of containment and is adjusted by the debris that will be "captured" by flow obstructions.

" Transport to the containment pool - the volume ratio of lower containment to all of containment and is adjusted by the debris that will be "captured" by flow obstructions.

" Debris retained in the compartment - one minus the debris transported to upper containment minus the debris transported to the containment pool.

o Table displays the blowdown "capture" fractions of the DDTS and the implemented "capture" fractions for the debris transport calculation.

Table 2: Blowdown "Capture" Fractions CEESI "Capture" "Capture" Percentage for Wetted Percentage Tests Implemented I-Beams & Pipes 7% to 14% 0%

V-Grating 21% to 36%

Split Grating 16% to 29%

Continuous to 29%

Grating4%

Grating 900 Bend 3% to 31% 3%

NOC-AE-1 5003220 Attachment 5 Page 5 of 40 Washdown transport - the transport of debris by containment spray and break flow where debris may be captured by only gratings. To reiterate, washdown has the potential to reduce the amount of debris available for transport to the strainers because debris may be held-up or captured by gratings. This phenomenon is referred to as capture in this RAI. The following is a list of conservativisms, assumptions, and methodologies used in the determination of the washdown transport fractions:

o Washdown transport fractions are determined for upper containment and break locations where debris remains in the compartment and are subjected to the containment sprays; i.e., the steam generator compartment.

o LDFG fines are not captured by gratings. Therefore, 100% of fines transport to the containment pool.

o For non-fine debris, <1% to 48% of debris passes through the grating per Table 4-3 of the DDTS. The transport calculation implemented a grating pass through of 50% for the first grating and a grating capture of 0% for each additional level of grating.

o The sprays were also assumed to always be initiated for washdown analysis.

Pool fill transport- the transport of debris by sheeting flow caused by break and containment spray flows to the emergency core cooling system (ECCS) sumps or inactive cavities.

o Due to the location of the ECCS sumps and possible break locations, pool fill transport was delineated into breaks inside and outside the secondary shield wall.

o Determined from a first order differential rate equation, and only transports fine debris that is located on the floor during injection.

o Transports debris to the strainers and inactive cavities.

Recirculationtransport- the transport of debris from the active portions of the recirculation pool to the sump strainers which was determined by computational fluid dynamic (CFD) simulations. The following is a list of conservativisms, assumptions, and methodologies used in the determination of the recirculation transport fractions:

o CFD models were not simulated for all the break locations.

A large break in the primary loop was assumed to be representative for the steam generator compartment break, below steam generator compartment break, and reactor cavity break. Although the flow paths are somewhat different for the primary loop break and the reactor cavity break, this application is conservative because the energy of a reactor cavity break would largely dissipate before reaching the main pool.

NOC-AE-15003220 Attachment 5 Page 6 of 40 A large break in the safety injection (SI) pump discharge line of Loop B was assumed to be representative for breaks in the pressurizer compartment, pressurizer surge line, RHR compartment, and annulus. This is reasonable since the CFD model analyzes a LBLOCA outside the secondary shield wall, and the largest break that would occur in the pressurizer compartment would be a MBLOCA.

o The minimum LBLOCA containment pool height was modelled. This is conservative because the minimum water height produces larger bulk velocities than a containment pool with a larger height (ii.).

o The total flow rates in (via the containment spray and break flow) and out (via the strainers) of the model was the maximum, two train operation flow rate of 14,040 gpm.

Erosion transport- the generation and transport of fiber fines eroded from small and large pieces of LDFG held up on structures in the pool and upper containment was assessed using data from the DDTS study and 30-day generic erosion testing (iv.). The following is a list of conservativisms, assumptions, and methodologies used in the determination of the erosion transport fractions:

o A spray erosion fraction of 1% for fine fiber generation and transport was applied for all small and large LDFG debris held up on structures above the pool elevation. This erosion fraction was applied for all break sizes independent of whether sprays would realistically be on or off for a specific scenario.

o A pool erosion fraction of 7% for fine fiber generation and transport was applied to all small and large LDFG held up on structures in the recirculation pool. The 7% erosion fraction represents the upper bound of the 95% confidence of the mean erosion value (i.) from generic 30-day erosion testing (v.).

The methodology described above produces transport fractions that are realistic and conservative.

References:

ii. ALION-CAL-STP-8511-08. "Risk-Informed GSI-191 Debris Transport Calculation." Revision 3. 6/10/2014.

iii. ALION-CAL-STPEGS-2916-005, "Containment Recirculation Sump Evaluation: CFD Transport Analysis. Revision 3," October 21, 2008.

iv. ALION-SUM-WEST-2916-01, "CAD Model Summary: South Texas Reactor Building CAD Model for Use in GSI-191 Analyses. Revision 4," May 22, 2014.

v. ALION-REP-ALION-1006-04, "Erosion Testing of Small Pieces of Low Density Fiberglass Debris - Test Report, Revision 1," November 7, 2011.

45. For question 6.a. of the April 15, 2014, RAI, the NRC staff finds that the licensee did not provide an adequate response to the question. The Drywell Debris Transport Study

NOC-AE-15003220 Attachment 5 Page 7 of 40 (DDTS) states that if gratings do not cover an entire transport path that they may not be as effective in debris capture as noted in the test metrics. Simply using a ratio of open area to total area may not provide a realistic or conservative estimate of debris capture. The grated area is likely to have higher resistance to flow that will increase as it collects debris.

Debris is generally assumed to be homogeneously distributed throughout the blowdown flow. If less volume of blowdown passes through the grating due to flow resistance, less debris is available to pass through or collect on the grating. The Nuclear Energy Institute (NEI) baseline guidance assumes that small fines are debris that will pass through gratings, so no holdup of small or fine fibrous material is assumed using baseline methodology. The baseline further assumes small fines to be the basic constituent of the debris for transport purposes. There were no refinements regarding crediting gratings to reduce transport found in either NEI 04-07 or the NRC SE on 04-07. Therefore, the licensee should justify the assumption that the amount of debris captured by gratings in pathways that are not fully covered can be estimated using a simple ratio of the open area to total area. Please provide a justification that the debris capture metrics used in the evaluation are realistic considering the issue identified above.

Response

The follow up inquiry, Round I RAI, SSIB 6a, implies that in LAR Encl. 4-3, during blowdown, a portion of small and large debris was estimated to be captured (or held up) on grating, including partial area grating, and hence not susceptible to transport to the sump strainer. This is not the case.

Figures of fibrous debris collected on gratings during the drywell integrated effects tests are shown below (Figure 1) from NUREG/CR-6369, Vol. 2 Pgs. 3-29, Figure 3-22 and 3-23 [1.]. These tests were performed with "structural elements assembled to the prototypical congestion level." It is qualitatively suggested by the figures below that the amount of congestion associated with homogenous fiber accumulation would not be large enough to greatly affect flow resistance through the gratings. Furthermore, the study (NUREG/CR-6369, Vol. 2, Pg. iii.) concluded that capture efficiency of all structures was found to be a "weak function of flow velocity and local flow patterns" [1.].

NOC-AE-1 5003220 Attachment 5 Page 8 of 40 ft-ur 34-2L. TYpOcaderbi &pui - WOl padog CT- 112). Plgur 3-23. TyW~Al debikts deeden - Vr-grmii (Teo 112).

Figure 1 - Fibrous debris collected on gratings during the drywell integrated effects tests from NUREG/CR-6369, Vol. 2, Pgs. 3-29 To clarify, blowdown analysis done in support LAR Encl. 4-3 does not use capture metrics from gratings to reduce the amount of debris available to transport. For example, no amount of debris captured by gratings is assumed to be stuck (held-up) and not available for other transport mechanisms.

In the blowdown transport phase in LAR Encl. 4-3, the only use of grating "capture" is to estimate the ratio of debris that would transport to upper containment versus remaining in the SG compartment or transporting to lower containment. None of the debris is assumed to be captured (and hence not susceptible to transport) either on full area grating, partial area grating or other hold-up mechanisms in the blowdown phase calculation.

Instead, after blowdown phase, all generated debris is available for remaining transport modes. This is illustrated in the transport logic diagrams in LAR Encl. 4-3, Ref. [23], where the total generated quantity of debris is distributed between levels of containment and subject to subsequent transport modes. An excerpt example, Figure 5.12.2 - Small piece fiberglass debris transport logic tree (SG compartment break), from LAR Encl. 4-3, Ref [23], is shown below.

NOC-AE-1 5003220 Attachment 5 Page 9 of 40 i, ow. W hd we. I Pod Fa Transport

• Trapof TransorFt OM 0.27 15S bsio comiery Vie COFABmneM SWWI7 wagbl Dow.

0.73 RM -'o LIWG (SIOd 0PN 0.27 In eSooft"q sOMOM w 0.00 Dsow.

o.* o.,

1.00 AcdOv Pool in Lower Active Swup(s)

Conthnn MHOKcSO. SinM1uRPMa 0.00 Figure 2 - LAR Encl. 4-3 -Figure 5.12.2 During the blowdown transport phase, the use of a best-estimate grating hold-up fraction, (as opposed to a lower-bound value) results in minimizing the quantity of debris that is considered to transport to upper containment.

This is conservative and has precedent from the staff evaluation of NEI 04-07 Volume 2 (Staff Evaluation for GR Section 3.6.3, Pg. 58) which states "For mostly compartmentalized containments, the GR recommends no debris be transported to upper containment" [3.]. STP's containment includes direct pathways to upper containment; hence incorporation of reductions in debris transported to upper containment is conservative All consideration of gratings in the STP blowdown transport analysis reduce the fraction of debris blown to upper containment without reducing the quantity of debris that remains available for subsequent transport modes.

NOC-AE-1 5003220 Attachment 5 Page 10 of 40

REFERENCES:

1. NUREG/CR-6369, Vol. 2. "Drywell Debris Transport Study: Experimental Work."

September 1999.

2. NUREG/CR-6369, Vol. 1. "Drywell Debris Transport Study". September 1999.

3. NEI 04-07, Vol. 2. "PRESSURIZED WATER REACTOR SUMP PERFORMANCE EVALUATION METHODOLOGY." Revision 0. December 2004.

46. The licensee's response to question 7.b. of the April 15, 2014, RAI, stated that the significantly longer washdown periods at STP, compared to the length of the DDTS washdown tests are inconsequential to the STP evaluation. The conclusion is based on a portion of the NEI guidance document, NEI 04-07, that found the erosion of fibrous debris by containment spray is less than one percent. The RAI aimed at the erosion of fibrous debris by containment spray, but requested for clarification if the washdown of fibrous debris through gratings would increase above that found during the DDTS and if the washdown time is significantly increased? The NRC staff is specifically interested in the small fiber washdown transport fractions provided in Table 2.2.23 of Volume 3 of the licensee's submittal dated November 13, 2014. These values are currently listed as 7-19 percent washed down in the annulus and 21-27 percent washed down inside the secondary shield wall. These do not appear to be fibrous erosion values. Please provide justification that the washdown values from a 30-minute test are applicable to the STP condition considering the clarification provided.

Response

In the RoverD methodology, it is slightly more conservative to assume that small debris is captured on structures and calculated to erode, thereby adding to the fine fiber transported to the sump pool. The following response supports the original STP methodology for debris transport.

Based on the discussion that follows, there is no basis for assuming that washdown of fibrous debris through gratings would increase above that found during the DDTS if the washdown time is significantly increased.

Section 4.4.1, Confirmatory Tests, of the DDTS (Volume 2, Pg. 4-5) includes the following conclusions:

1. 2. Most of the Small debris pieces will be washed down by water within first 10-15 minutes after which washdown reaches an asymptote.

1. 3. Large pieces will not be forced through the grating even at high flows.

They will remain on the grating and may erode with time. Erosion also exhibits an asymptotic behavior.

NOC-AE-15003220 Attachment 5 Page 11 of 40 The "Small debris" category in the DDTS (Volume 2, 4-3) is described as "a light, loose, and well-aerated texture with an average density lower than 0.25 Ibm/ft3 usually consisting of loose clusters of individual fibers.

Typically these pieces were about 1.5" in size and possessed little of the original structure or the chemical binding. ... " The "Medium" category in the DDTS is described as "Insulation debris pre-torn from the blanket by an air-jet impingement. These pieces keep some of the original structures in the inner regions, while they look torn-down or loose on the outside. Typically these pieces are about 6"x4" in dimension."

The size distribution used in the current analyses are based on (proprietary) ALION-REP-ALION-2806-01, Rev: 3. The size distribution categories are: Fines (Individual Fibers), Small Pieces (< 6" on a Side),

Large Pieces (> 6" on a side) and Intact (covered).

The "Small debris" category in the DDTS corresponds to the Fines category in STP calculations on the basis that the clumps are collections of individual fibers with "little of the original structure."

• The "Medium" category in the DDTS corresponds to the Small Pieces category in STP calculations. Debris in this category is generally larger than the grating void sizes and hence is not expected to be "be washed down by water within first 10-15 minutes" as described in DDTS Section 4.4.1, Confirmatory Tests, conclusion #2, above, as was the case for Small DDTS debris.

STP Small Pieces debris behavior corresponds to DDTS Section 4.4.1, Confirmatory Tests, conclusion #3, "...will not be forced through the gratingeven at high flows ... " It is noted that this DDTS conclusion does not have any limitations with respect to time.

DDTS 4.5, Summary and Conclusions, items states: "2. A significant fraction of the medium pieces (generated by jet impact on insulation blanket) would be eroded and transported to the drywell pool. A transport factor of 1.0 is recommended in the case of break overflow (e.g.,

following a recirculation line break); on the other hand, for sprays a transport factor of 0.5 appears reasonable." The DDTS recommendation for the sprays-related transport factor, 0.5, which was used as the basis for the washdown transport fraction in STP debris transport washdown calculations, does not include any flow duration-related restriction or cautions.

The very fact that DDTS washdown and erosion discussion is focused primarily on erosion indicates that wash-through for debris of sufficient size, i.e., greater than the void space of grating, is not expected to be an issue within an extended post-LOCA time frame. On the contrary, even the time frame of erosion, which can only happen if debris remains retained on grating, is said to be asymptotic after a short period of exposure to flow.

NOC-AE-1 5003220 Attachment 5 Page 12 of 40 On the basis of the discussion above, there is no basis for assuming that washdown of fibrous debris through gratings would increase above that found during the DDTS if the washdown time is significantly increased.

47. In question 14 of the April 15, 2014, RAI, the NRC staff requested the basis for the use of 1/16 inch as the value below which a filtering bed is assumed not to occur. The licensee's response to the question is based on NRC staff's acceptance of the head loss correlation and a sensitivity study that showed no change in OIDF if the criterion is reduced to zero inches. Because neither has been accepted at this time, the acceptability of the response to RAI 14 is indeterminate. Additionally, the use of a 1/1 6-inch criterion below which chemical effects cannot occur is not supported by some industry tests that had 1/16 inch of fiber or less added. Some tests had measureable increases in head loss with less than 1/16-inch theoretical fiber on the strainer after chemicals were added to the loop. The NRC staff agrees that it is unlikely that a head loss great enough to result in strainer failure will occur with such a low fiber load.

However, the potential for the head loss to result in flashing or additional deaeration was not addressed by the licensee. The sensitivity study was also conducted before corrections to pool level and clean strainer head loss (CSHL) values were implemented.

As stated above, the NRC staff has not accepted the head loss correlation used to perform the sensitivity study. The licensee is requested to provide revised response to RAI 14 considering the information discussed above.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for head loss. Head loss is accounted for in the plant-specific deterministic testing.

NOC-AE-15003220 Attachment 5 Page 13 of 40

48. Questions 15, 16, 17, 18, 21, and 22 of the April 15, 2014, RAI, requested additional information regarding the licensee's use of a correlation to calculate debris head loss. The NRC staff has established a position that correlations may not be used to calculate head loss unless the correlation is validated, under plant-specific conditions, for the range of conditions to which the results will be applied. This position was discussed with the licensee before the formal submittal. The NRC staff does not consider the responses to be adequate since the licensee's use of correlations were not validated under plant-specific conditions. The licensee is requested to provide a revised response consistent with the NRC staff position.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for head loss. Head loss is accounted for in the plant-specific deterministic testing.

49. The licensee's response to question 27 of the April 15, 2014, RAI, stated that the use of 0.220 ft as the CSHL value was an error. The licensee performed sensitivity studies to determine the effect of using the correct value of 1.952 ft on overall CDF. The licensee stated that the change in CDF would be about 18 percent when the correct value is used.

The licensee also stated that a more accurate CSHL value would be used. Does it mean that 1.952 ft is the "more accurate" value of CSHL? If not, please provide the "more accurate" value of CSHL that will be used in future calculations.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for head loss. Head loss is accounted for in the plant-specific deterministic testing. However, the correct value of CSHL for use in calculations is 1.952 ft.

50. The licensee's response to question 28 of the April 15, 2014, RAI, stated that the use of a head loss correlation is essential to the risk-informed method because it provides understanding of subtle interactions between variable parameters considered in the analysis. However, the need to apply a 5X safety factor to bound uncertainties in the correlation indicates that confidence in the method is relatively low and that evaluation of interactions between the parameters may be significantly skewed. These relationships may be further mischaracterized by resorting to a limiting packing factor for the debris bed.

NOC-AE-15003220 Attachment 5 Page 14 of 40 The response provides a sensitivity study for safety factor values around the 5X value used in the evaluation. However, the response does not provide a basis for the values used in the study. The NRC staff believes that because there are uncertainties in many aspects of the model and that many of these are significant, that the 5X multiplier may not envelope these uncertainties. The RAI response does not appear to address two significant issues, the uncertainty caused by non-homogeneous beds and the lack of testing to validate the model for plant-specific conditions that lead to model uncertainty.

Other uncertainties inherent to the use of correlations for head loss should also be addressed including statistical uncertainties arising from the use of test data, uncertainties arising from the use of the correlation, and uncertainties introduced by assuming that test conditions are representative of the plant. Please provide an evaluation of how the individual uncertainties within the model are accounted for and provide an estimate of the total uncertainty created by use of the model.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for head loss. Head loss is accounted for in the plant-specific deterministic testing.

51. The licensee's response to question 31 of the April 15, 2014, RAI, described a calculation that evaluates the potential for the collection of gas bubbles in the STP strainer. The licensee cites Reference 56 of Volume 3, TDI-6005-07, "Vortex Air Ingestion and Void Fraction South Texas Project Units 1 and 2," Revision 3, November 17, 2008, which evaluates the transport of gas voids in the piping between strainer and ECCS and CS pumps. Neither a copy of the referenced document nor any applicable details from the reference were provided to the NRC staff. It was also not described how it was determined that voids would not collect in the strainer. Please provide a summary of the relevant sections of Reference 56 describing how it was determined that voids would not collect in the pump suction piping. Additionally, please provide information that evaluates whether voids can collect within the strainer, and if they do, how the effect was evaluated.

Response

Vortex, Air Ingestion, and Void Fraction The December 2008 submittal in response to GL 2004-02 discussed the potential for vortexing, air ingestion, and void formation for the STP sump strainers made by PCI. STP strainer prototype testing at Alden Research Laboratory verified that the minimum 1 2 in. submergence would preclude air ingestion or vortex development. Subsequent discussion was held with the NRC staff during the September 13, 2010 public meeting conference call concerning RAIs. The NRC staff noted that vortexing is not likely to be an issue for PCI made strainers based on testing by STP and others that show vortexes will not occur for conditions bounding the STP conditions. Due to lack of an air entrainment mechanism (i.e. vortex formation) along with

NOC-AE-1 5003220 Attachment 5 Page 15 of 40 complete submergence of the strainer, air ingestion is not expected to occur.

Also discussed in the December 2008 submittal was an evaluation of void fraction that concluded that flashing and subsequent void fraction formation would not occur across the strainer.

The vortex, air ingestion, and void fraction analysis concluded that void fraction occurring at the strainer debris bed due to head loss and the accompanying post-LOCA conditions would be reversed and any voids would have collapsed before the strainer discharge fluid left the containment sump and entered the ECCS/CSS inlet pipe. The net void fraction (i.e., net air production) is therefore 0%. Therefore, void fraction is not an issue for any of the post-LOCA fluid associated pressure and temperature combinations associated with the subject fluid flow from the strainer to the ECCS/CSS inlet pipe.

Trapped Air in Plenum Box The strainer configuration is such that sump water goes into the strainer module and then goes to the core tube where it is directed to the plenum box. There are four inlets to the plenum box (one for each connected string of strainer modules). The plenum box collects the discharge flow from the strainer modules and directs the flow downward to the sump pit which contains the inlet of the suction pipe to the ECCS and CSS pumps. Vortex breakers are installed in the sump pit around the inlet to the suction pipe.

Upon flooding of the strainer modules and the sump pit during the initial post-LOCA pool fill-up phase, some air may be trapped under the cover of the plenum box. This air does not constitute a blockage of water flow from the strainers to the sump pit. Any trapped air in the plenum box does not increase the clean strainer head loss or interfere with water flow. The trapped air will slowly dissipate during operation of the ECCS and CSS pumps.

Note The response to the 1 st Round RAI referred to a document concerning gas voids in the piping between the sump strainers and the safety injection pumps and containment spray pumps. This document (Reference 58) was prepared by MPR for STP in response to GL 2008-01 Managing Gas Accumulation. It is a calculation that determines the maximum acceptable gas void volumes for particular locations in ECCS and RHR piping based on industry acceptance criteria for the gas volumes allowed to transport to the system pumps. Since it is not concerned with sump strainer performance and is germane only for gas accumulation management, it should not be part of the response to this RAI.

NOC-AE-1 5003220 Attachment 5 Page 16 of 40

52. The licensee's response to question 33 of the April 15, 2014, RAI, stated that the CASA Grande model overestimates the water level compared to computer aided design calculated levels. The licensee stated that the error will be corrected so that future submittals contain accurate pool levels. However, the licensee also needs to verify that strainer submergence is adequate and that vortexing, deaeration, and flashing

Response

The water level calculation for RoverD uses the deterministic evaluation of water level that was described in the December 2008 submittal for the GL 2004-02 response (ML083520326). This was the basis for the testing that showed acceptable submergence. See response to RAI 31 that explains vortexing, deaeration, and flashing will not occur is based on testing and conservative assumptions in the level calculation. The transport evaluation is also described in the December 2008 submittal and is consistent with the sump level evaluation.

53. The licensee's response to question 34 of the April 15, 2014, RAI, stated that total CSS flow is determined by multiplying the random pump flow rate by the number of operable CSS pumps. These flow rates are randomly selected from between the maximum calculated flow rate and some minimum value. It was not clear that using random values is appropriate and how the minimum values were calculated. The licensee also stated that for all two and three train cases that CASA Grande uses the higher two train flow, since it is conservative. The licensee included reference to Reference 42, Volume 3, 5N109MB01024, "Design Basis Document Containment Spray," Revision 3, November 17, 2004. Neither a copy of the referenced document nor any applicable details from the reference were provided to the NRC staff. Please summarize the relevant information from Reference 42, provide the methodology used to determine the minimum flow rates, or provide the basis for using random flow rates for each event instead of calculating event specific flow rates.

Response

The minimum and maximum values used for two train operation were 1932 and 2350 gpm respectively (Volume 3, Section 2.2.8). The minimum flow rate (1932 gpm) used for two and three trains operable scenarios was taken from STP's "DESIGN BASIS DOCUMENT CONTAINMENT SPRAY SYSTEM" (Volume 3 Ref. 42, Pg. A-40). This flow rate is the minimum probable flow rate per train calculated using FLOMAP (Volume 3 Ref. 42, Pg. A-40). This minimum flow rate was calculated with the following simplifications and assumptions.

• Piping and fitting resistances based off of plant configuration and Crane 410 methodology

• 5 percent degraded pump curve

• Maximum containment design pressure

NOC-AE-1 5003220 Attachment 5 Page 17 of 40

• Minimum Tech Spec RWST level The maximum flow rate per train (2350 gpm) used for two and three trains operable scenarios was taken as the FLOMAP calculated average of design flows for trains A and B operation during recirculation (Volume 3 Ref. 42, Pg.

A-39).

The minimum and maximum user entered values for one train CS operation were 2080 and 2600 gpm respectively. The maximum (2600 gpm) flow rate for one train operation was specified in Volume 3 Ref. 41, Pg. 16. The minimum value, for one train operation, was taken as 80% of the maximum value (Volume 3 Ref. 41, Pg. 16); where the 80% scaling was taken as the ratio of minimum to maximum flow rate from the two train flow case.

Sampling CS flow rates for each scenario's respective operable train state is appropriate because no preference was added (random and equally probable) between the minimum and maximum flow rate values, and because minimum values were selected or scaled to represent probable outcomes. Selection of random flow rates between minimum and maximum limits is a common approach for rigorous uncertainty propagation in cases where physical variability or competing mechanisms preclude definitive selection of conservative parameter values. Containment spray rate is sampled in this case because (1) there are no initiating-event specific (break size dependent) flow rates available for the CS pumps; (2) CS flows are most dependent on initiating-event independent parameters such as the RWST level, initial pumps available, and variance in pump performance that affect CS flow within the applied ranges; and (3) fiber accumulation rate in the fuel is affected by the flow split diverted to sprays, so all probable ranges of CS flow rate should be exercised to determine the quantitative impact on all failure modes.

54. The licensee's response to question 36 of the April 15, 2014, RAI, states that strainer buckling is the limiting failure criterion when compared to NPSH. It was not clear that flashing was considered as a failure mode for the strainer in the STP submittal. Please state how flashing across the strainer is evaluated by CASA Grande since this failure mode may be more limiting than strainer buckling when the fluid temperature is high.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for head loss. Head loss is accounted for in the plant-specific deterministic testing. Flashing was addressed in STPNOC's December 11, 2008, letter (ML083520326).

NOC-AE-1 5003220 Attachment 5 Page 18 of 40

55. For question 41.c. of the April 15, 2014, RAI, the NRC staff has accepted the use of mitigative measures to address defense-in-depth. The licensee credited backwash of the strainers as a mitigative measure. However, it was further stated that the mitigative measures for backwash of the ECCS strainers have not been proceduralized. Please describe the procedural requirements that are in place to initiate ECCS strainer backwash or revise the submittal to remove its credit.

Response

Strainer backwash from the RWST is initiated from SACRG-2 (Severe Accident Control Room Guideline After the TSC is Functional), Addendum 2 (which directs entering SAG-3) after the TSC is activated by direction through the TSC Diagnostic flow chart when the CETs indicate greater than 7080 F. Further guidance is given in Step 5.b.4 of SAG-3 (Inject into the RCS) for operation with RWST in backwash alignment.

55A. CASA Grande uses a distribution for the temperature at which chemical effects are assumed to occur and a distribution for the conventional head loss bump up factor.

Volume 3 states that chemical effects are assumed to occur below 140OF and that the conventional head loss bump-up factor is 5. Please state which methodology is intended to be used and update the documentation or the model to reflect the intended methodology.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for chemical effects or head loss. Head loss, including chemical effects, is accounted for in the plant-specific deterministic testing.

56. CASA Grande does not implement the bed compression aspects of the NUREG-6224 Correlation. Volume 3, equations 33-38 imply that the compression function is implemented in CASA Grande. The NRC staff understands that this issue was addressed by implementing a limiting bed compression for all debris head loss calculations. Please verify that this has been accomplished and provide updated results based on the updated method. Please provide the basis for the assumption that the limiting bed compression chosen is appropriate.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic

NOC-AE-1 5003220 Attachment 5 Page 19 of 40 testing to failure. RoverD does not rely on a correlation or model to account for head loss. Head loss is accounted for in the plant-specific deterministic testing.

57. The NRC staff has several concerns with the model used for fiber penetration through the strainer. Considering the issues described in this RAI, the NRC staff does not have high level of confidence that the debris penetration model accurately represents the expected debris penetration and in-vessel fiber accumulation that could occur in the plant. Please provide information that justifies that the CASA Grande calculations for fiber penetration are meaningful and represent the plant conditions:

a. Assumptions and modeling techniques regarding debris arrival timing and filtration may result in non-conservative bypass results. In the response to question 6.b. of the April 15, 2014, RAI, the licensee stated that early arrival of debris at the strainer resulted in higher filtration and lower total bypass. The response to RAI 11 b stated that debris transported during pool fill is placed directly on the strainer at the initiation of the LOCA. This is also related to the "non-intuitive results found during a sensitivity study provided to the NRC staff for review. The NRC staff believes that the result is non-intuitive because it is non-physical. Debris arrival timing should not have a significant effect on filtration, if realistic timing is used. The staff understands that placing fiber on the strainer at the start of recirculation may be conservative with respect to head loss, but may be non-conservative with respect to strainer penetration. The NRC staff has determined that assuming homogeneous mixing of fiber in the pool at the start of recirculation rather than assuming that some fiber transports to the strainer prior to recirculation is likely to be more conservative. The NRC staff understanding is based on the relatively short time during which significant bypass occurs and the longer time over which head loss becomes more risk significant. Please provide information that justifies the STP approach is conservative or incorporate a methodology that is more appropriate.

Response

RoverD does not use the filtration model used in CASA Grande. RoverD uses its own filtration model that assumes no fiber on the sump screen at the start of recirculation. In RoverD, STP directly applies measured test data including the uncertainty bounds (obtained from measurements) to account for bypass uncertainty. The data are fit to the upper, central, and lower bound of measurement uncertainty. Assuming no fiber on the strainer when recirculation begins should maximize the amount of fiber penetration to the core.

NOC-AE-1 5003220 Attachment 5 Page 20 of 40

b. If the existing model or a model that results in penetration being highly dependent on arrival timing early in the event is maintained, please justify why the model is not more correlated to the amount of debris arriving at the strainer regardless of timing. If debris arriving at the strainer at the initiation of the LOCA affects the calculated bypass amount please justify this model behavior. Does the model assume that early arriving material can pass through the strainer? If not, please justify the assumption. Also, please provide justification that less debris would bypass the strainer in the plant if debris arrives at the strainer earlier in the scenario, that is, the model accurately reflects plant performance.

Response

RoverD does not use the filtration model used in CASA Grande. RoverD uses its own filtration model that assumes no fiber on the sump screen at the start of recirculation.

c. How are the uncertainties resulting from applying bypass test results to the plant condition accounted for in the model? Are there conditions potentially present in the plant that would result in more bypass than occurred in the relatively controlled test conditions? Please explain.

Response

In RoverD, STP directly applies measured test data including the uncertainty bounds (obtained from measurements) to account for bypass uncertainty.

The data are fit to the upper, central, and lower bound of measurement uncertainty. Different conditions (for example flow rates and concentrations) are included in the measured test data and appropriately accounted for in the uncertainty bounds of the fit to the data.

The test data fit for the different bounds is shown in the figure.

NOC-AE-1 5003220 Attachment 5 Page 21 of 40 1

0.95 0.9

• Test 1: 353gpm

• Test 2: 353gpm 0.85 C Test 3: 353gpm 0.8 Test 5: 358gpm

• Test 7: 220gpm 0.75 Fit 0.7 -Upper Envelope

-Lower Envelope 0.65 0.6 0.55 0 500 1000 1500 2000 2500 3000 3500 4000 Strainer Mass In Grams STP PCI Strainer data shown with filtration fits from test measurements at different levels of fiber accumulation shown as fits to lower bound of data, central fit of data, and upper bound fit of data.

d. How are uncertainties associated with the strainer bypass calculation accounted for? The calculation appears to be very sensitive to arrival timing. Also, how are uncertainties that arise from testing and the translation of test results into bypass models accounted for? Please explain.

Response

An actual strainer module was used to perform testing in order to eliminate concerns related to the complex design of the strainer surface. Different approach velocities were used as well as different concentrations. Test measurements from six tests were used to fit the data bounds of the data.

As described, other responses, the uncertainty bounds of the test measurements are directly evaluated in the RoverD approach as shown in Attachment 7.

NOC-AE-1 5003220 Attachment 5 Page 22 of 40 1

0.95 0.9

.0.85 0.8 IL 0.75 0.7 0.65 0.6 0 500 1000 1500 2000 2500 3000 3500 4000 Mass on Strainer (grams)

STP PCI Strainer filtration fractions from test measurements at different levels of fiber accumulation shown as fits to lower bound of data, central fit of data, and upper bound fit of data.

e. The NRC staff noted that changing the time step in the CASA Grande debris penetration model has a significant effect on the output (amount of debris reaching and accumulating in the core). CASA Grande uses a relatively inaccurate method to integrate the mass balance equations for debris accumulated in the core, especially early in the accident sequence after initiation of recirculation. Please describe how the licensee determined that the time step interval and integration method provide appropriate results (ideally, the conditional probability of failure by exceedance of the cold-leg break fiber limit should be independent of the computational time steps).

Response

The RoverD strainer bypass calculation uses implicit (Adams method) integration of the mass conservation equations. The method is well-known as a robust solver for non-stiff ordinary differential equations and is not subject to time step size issues associated with explicit methods. The method and equations are clearly developed and explained in Attachment 7.

NOC-AE-1 5003220 Attachment 5 Page 23 of 40

f. The NRC staff noted that one input parameter to the CASA Grande code to compute the filtration efficiency is one order of magnitude more than that determined by testing and documented in Volume 3 of the submittal (Table 2.2.28, parameter mtest:

the upper bound is 0.0003723 1/g; instead a value of 0.003723 1/g was apparently used in the CASA Grande computations in support of license submittals). The result of this error is overestimation of the filtration efficiency, which causes underestimation in the amount of fiber penetration and in-vessel accumulation. Sensitivity studies suggest that this error would underestimate the cold-leg break in-vessel fiber limit failure contribution to the CDF by about an order of magnitude. Please explain and include comparisons of filtration efficiencies and shedding rates computed by Monte Carlo sampling to test data in your response.

and documented in Volume 3 of the submittal (Table 2.2.28, parameter mtest: the upper bound is 0.0003723 1/g; instead a value of 0.003723 1/g was apparently used in the CASA Grande computations in support of license submittals). The result of this error is overestimation of the filtration efficiency, which causes underestimation in the amount of fiber penetration and in-vessel accumulation. Sensitivity studies suggest that this error would underestimate the cold-leg break in-vessel fiber limit failure contribution to the CDF by about an order of magnitude. Include comparisons of filtration efficiencies and shedding rates computed by Monte Carlo sampling to test data.

Response

The RoverD strainer bypass calculation uses the measured test data directly in the equations shown in Attachment 7. The parameters used are shown in Attachment 7 along with the inputs used in uncertainty bound calculations.

NOC-AE-1 5003220 Attachment 5 Page 24 of 40

58. The NRC staff reviewed the relationship between break size, and CASA Grande failure predictions. The results of the review indicate that there may be discontinuities in the results that suggest that failures due to certain break sizes are not predicted or are much less likely to occur than would be expected. For example one break sized at about 5 inches results in a failure. With respect to break size, no additional failures occur until the break size reaches about 10 inches. This behavior appears to be non-physical.

Please discuss this 'observation and provide an evaluation of whether this behavior affects the results of the analysis.

Response

The apparent discontinuity results from pipes being of discrete sizes and that there are varying numbers of the different size pipes. See the table below.

Pipe Sizes at STP and the Number of Welds Associated with Each Pipe Size STP Pipe Sizes STP # of Welds 0.614 32 0.815 3 1.338 9 1.689 85 2.125 6 2.626 26 3.438 90 5.189 88 6.813 54 8.500 30 10.126 131 12.814 10 27.500 16 29.000 20 31.000 28 628 There are 15 discrete pipe sizes at STP, and a total of 628 weld locations where a break can occur. Of these 15 discrete pipe sizes, breaks 13 inches and larger can only occur on 3 of them (20%). Of the 628 weld locations, breaks 13 inches and larger can only occur on 64 of them (10.2%). In addition, CASA Grande is set up to sample larger breaks at a given location more frequently than smaller breaks, so we would expect to see relatively few breaks between 13 and 20 inches on these larger pipes.

In conclusion, the break sizes going to failure are representative of the pipe sizes at the STP power plant and the likelihood of breaks on those pipes. The staff indicated that the behavior may be non-physical, when in fact, this

NOC-AE-1 5003220 Attachment 5 Page 25 of 40 behavior is a function of the 15 discrete break sizes at STP and the fact that smaller breaks are less likely to fail than larger breaks.

59. It is the NRC staff 's understanding that the computer-aided design (CAD) model used to determine debris generation amounts was developed under a 10 CFR 50, Appendix B program, and therefore treats the output to be accurate. However, it may not be the case for the debris generation values used in CASA Grande. Please describe the methodology used to import the CAD values into CASA Grande and provide information that describes how the debris generation amounts used by CASA Grande were validated to be accurate.

Please include information that demonstrates how the interfaces between the CAD model or its input to CASA Grande were validated to be correctly implemented and describe whether raw CAD values were validated to be the same as those used in CASA Grande.

Response

For clarity this response has been broken up into three major sections:

1) Import of CAD Geometry into CASA Grande, 2) Validation of CASA Grande Debris Generation, and 3) Conclusions.

Import of CAD Geometry into CASA Grande:

There are four types of geometry (Pipe Extract Insulation Data, Equipment Insulation data, Concrete and Steel Stereolithography files) that can be imported into a CASA Grande simulation. These four types of geometry and descriptions of how they are imported and used in the CASA Grande suite are described below.

Pipe Extract Insulation Data: Pipe Extract data is extracted from the piping assembly in the 3D containment CAD model by a proprietary AutoDesk Inventor add-in (created by AutoDesk for Alion) and includes all information about piping and piping insulation needed to rebuild the piping insulation geometry numerically inside of CASA Grande.

Specifically Pipe Extract data includes pipe segment lengths, pipe names, pipe insulation types, Cartesian coordinates of extracted points on pipes (Work-Point), bend radii of extracted Work-Points, inner and outer diameters of pipes, and Work-Point types (ie. valve, hangar, weld, etc...). An example of a pipe segment in a Pipe Extract input file is shown below in Figure 1.

/I

NOC-AE-15003220 Attachment 5 Page 26 of 40 12-11-26 South Texas Plant.iam Number of Points = 26. Number of Straights = 9. Unit of Length = Inches.

.ipt Name,Point,X,Y,Z,Rad,ID,OD,WPI 30MS-1002-GA2 [NUKON]:1,0,-137.14,369.14,1404.88,0,32.75,38.75, 30MS-1002-GA2 [NUKON]:1,1,-137.14,369.14,1441.89,0,32.75,38.75,WELD 30MS-1002-GA2 [NUKON]:1,2,-137.14,369.14,1496.75,49.12,32.75,38.75, 30MS-1002-GA2 [NUKON]:1,3,-193.84,367.73,1496.75,0,32.75,38.75,FW0060 30MS-1002-GA2 [NUKON]:1,4,-301.05,365.07,1496.75,49.12,32.75,38.75, 30MS-1002-GA2 [NUKON]:1,5,-301.05,365.07,1420.97,0,32.75,38.75,WELD1 30MS-1002-GA2 [NUKON]:1,6,-301.05,365.07,1271.75,0,32.75,38.75,FW0002 30MS-1002-GA2 [NUKON]:1,7,-301.05,365.07,1202.25,0,32.75,38.75,HL5016 30MS-1002-GA2 [NUKON]:1,8,-301.05,365.07,1173.99,0,32.75,38.75,HL5015 30MS-1002-GA2 [NUKON]:1,9,-301.05,365.07,1148.88,0,32.75,38.75,HL5009 30MS-1002-GA2 (NUKON]:1,10,-301.05,365.07,1047,49.12,32.75,38.75, 30HS-1002-GA2 [NUKON]:1,11,-343.48,407.5,1047,0,32.75,38.75,HL5008 30MS-1002-GA2 [NUKON]:1,12,-386.54,450.55,1047,0,32.75,38.75,WFLD2 30MS-1002-GA2 [NUKON]:1,13,-417.99,482.01,1047,49.12,32.75,38.75, 30MS-1002-GA2 [NUKON]:1,14,-461.28,438.72,1047,0,32.75,38.75,WELD3 30MS-1002-GA2 [NUKON]:1,15,-489.05,410.95,1047,0,32.75,38.75,11L5006 30MS-1002-GA2 [NUKON]:1,16,-613.41,286.59,1047,0,32.75,38.75,FW0004 3014S-1002-GA2 [NURON]:1,17,-660,240,1047,49.12,32.75,38.75, 30MS-1002-GA2 [NUKON]:1,18,-660,120,1047,49.12,32.75,38.75, 30MS-1002-GA2 [NUKON]:1,19,-660,120,986.02,0,32.75,38.75,HL5001 30HS-1002-GA2 [NUK<ON]:1,20,-660,120,964.3,0,32.75,38.75,HL5002 30MS-1002-GA2 [NUKON]:1,21,-660,120,801,49.12,32.75,38.75, 30HS-1002-GA2 [NUKON]:1,22,-721.12,120,801,0,32.75,38.75,FW005A 30KS-1002-GA2 [NUKON]:1,23,-834.94,120,801,0,32.75,38.75,FW0006 30HS-1002-GA2 [NUKON]:1,24,-849.94,120,801,0,32.75,38.75, 30MS-1002-GA2 [NUKON]:1,25,-957.94,120,801,0,32.75,38.75, Point to Point Length: 1748.53 Figure 1: Pipe Extract File Data Example The data from each pipe segment in the Pipe Extract file is read into CASA Grande and used to create a numerical reconstruction of the piping insulation volumes with point volumes called voxels. The user can specify the numerical resolution of the piping insulation reconstruction (with voxels) in the CASA Grande simulation by defining linear resolution and number of azimuthal bins in the input deck Figure 2.

~

NOC-AE-1 5003220 Attachment 5 Page 27 of 40 "Spatial Resolution for Discretizing Insulation"

% (must repeat weld target sort if these are changed)

% (delete all master files and rerun with new dell and Nangbin)

% Linear Resolution (inches) 6

% Azimuthal Bins in 2 Pi Radians on Pipes 12 Figure 2: Resolution Inputs for CASA Grande Piping Reconstruction An example reproduction of Pipe Extract data using the above user defined linear resolution and number of azimuthal bins (Figure 2) is shown below in Figure 3. Notice that there are 12 bands that run the length of the pipe curve which show the azimuthal discretization of the voxels into bins. Each point on the bands is in one azimuthal bin and approximately six inches (Linear Resolution) away from other points on the same band (with flexibility in linear discretization to account for curvature).

Figure 3: CASA Grande Representation of Curved Pipe Segment Spot checks are done on segments of piping insulation with each new set of Pipe Extract data that is loaded into CASA Grande using the CAD software's geometry as the baseline for comparison. The Inventor 2013 representation of the insulation segment is shown below in Figure 4

NOC-AE-1 5003220 Attachment 5 Page 28 of 40 When the volume of the CASA Grande (3.2300E4 in 3) and Inventor 2013 CAD representation (3.0954E4 in 3) of the insulation segment were compared the percent difference between the volumes for this example was found to be 4.25%.

1. Equipment Insulation Text Files: The equipment insulation import format has been updated since V1.6 of CASA Grande to the more accurate input format introduced in V1.7. This equipment insulation format requires the user to supply a text file for each piece of equipment; where the data of the equipment insulation text file contains x,y,z locations (inches), point volume (V) value (in3) and insulation type for each of the voxels that discretize equipment insulation. An example of input from an STP equipment insulation text file is given below in Figure 5; where the data in each row is formatted to read x, y, z, V, and Insulation Type respectively.

NOC-AE-15003220 Attachment 5 Page 29 of 40 16.207766, -685. 957510, 720.110344, 0.022624, Nukon 27.294486, -691.990374, 728.102136, 18.531318, Nukon 10.670278, -723.836132, 747.446880, 3.626578, Nukon 55.824473, -664.156506, 750.493317, 1.273422, Nukon 11.788651, -691.779606, 724.878445, 5.793195, Nukon

-1.637679, -638.459124, 746.120945, 9.135291, Nukon 25.550024, -690.241014, 724.621722, 8.304555, Nukon

-14.718718, -709.509252, 741.547874, 11.515781, Nukon

-29.648457, -662.100630, 752.569931, 0.326975, Nukon

-6.902767, -664.377736, 726.835512, 14.324231, Nukon 31.714070, -638.056496, 752.493917, 0.517816, Nukon

-23.340283, -648.986673, 751.178219, 1.241279, Nukon

-22.066737, -673.506339, 735.670522, 6.409216, Nukon 16.545730, -631.722195, 751.710571, 0.253556, Nukon

-6.656185, -636.577825, 751.837126, 0.811487, Nukon

-0.693392, -677.147776, 711.787234, 0.727560, Nukon

-3.228770, -635.993839, 748.933209, 2.804510, Nukon 10.386821, -686.880591, 719.988258, 0.028539, Nukon

-18.413075, -642.886762, 751.702785, 0.336778, Nukon 57.469826, -670.640285, 750.774016, 0.862577, Nukon Figure 5: Example text from equipment insulation input file Because of the simplicity of the Equipment insulation format these files can be created in an Excel spreadsheet. For STP however these files were created from STL exports (for high resolution) of equipment from the CAD software. These STL files were then pre-processed to supply the Cartesian data summarized in Figure 5. Note that it is also possible to import piping insulation or any other insulation into the model using this input method.

I Concrete Stereolithography (STL) file: The concrete input file is a binary STL data file containing all CAD geometry of the plant concrete structures. The concrete STL file is used to represent robust barriers (insulation shielding),

and for concrete coatings destruction. The concrete STL file is interpreted as a collection of surface triangle faces (facets) and respective unit surface normals in three space. For concrete coatings calculations these triangles are refined to a user specified surface area to ensure that coatings quantities are calculated accurately. As an example, a picture of the CASA Grande reconstruction of the STP concrete STL data is shown below in Figure 6.

Note that this image is the direct import used as destruction barriers and does not represent refinements made for qualified coatings destruction.

NOC-AE-1 5003220 Attachment 5 Page 30 of 40 Figure 6: CASA Grande reconstruction of concrete STL input file When the concrete file is imported into CASA Grande the file is visually inspected for errors. First the model is checked to make sure that triangles aren't visually overlapping. Note that there is a numerical STL checker in CASA Grande, but the visual inspection is for added protection against STL data interpretation errors. Next the triangle normal vectors are visually inspected to make sure that they are pointing out of the surface. These checks insure that the CASA Grande interpretation of the concrete file will correctly simulate barriers between breaks and insulation targets.

2. Steel STL file: The steel input file is a binary STL data file containing all CAD representations of plant steel structures. The steel STL file is only for steel coatings destruction calculations; steel structures are not used for insulation shielding. The steel STL file is imported in CASA Grande in the same format as the concrete STL file. For coatings calculations these triangles are refined to a user specified surface area to ensure that steel coatings quantities are calculated accurately. For most plants analyzed the user specified triangle refinement surface area is set to 16 in2 which gives good refinement over the break spectrum. Any coarser refinement area specified will decrease simulation run time but will be less accurate.

Validation of CASA Grande Debris Generation The STP CASA Grande input geometry has been verified for import accuracy, and calculated debris generation in CASA Grande has been bench-marked against CAD calculated values.

NOC-AE-15003220 Attachment 5 Page 31 of 40 Import accuracy checks in CASA Grande have been automated. A line is available to assign the CAD calculated total volume of each imported insulation type in the input deck ('Debris Volume from CAD Model' input in Figure 7 Below).

% Debris Type [1]

1

% Debris Name "Low-Density Fiberglass (LDFG)"

% Number of CAD Debris Labels 8

% CAD Debris Labels "NUKON" "NUKON 2" "NUKON INS" "Nukon" "001 NUKON" "004 NUKON" "THERMAL WRAP" "ThermalWrap"

% Debris Volume from CAD Model (ft^3) 9893.498 Figure 7: 'Debris Volume from CAD Model' input When running CASA Grande the user entered 'Debris Volume from CAD Model' input value, is compared to its corresponding imported insulation type. This comparison is automatically written to a file in the outputs of the simulation in the 'CASAvsCADInsulVol.txt' text file, and can be directly processed as a common delimited file in Excel to give a comparison table. STP's import comparison table is shown below in Table 1.

Table 1: STP CASA Grande Vs. CAD insulation volumes import comparison CAD CASA Insulation Grande Ratio Debris Type Volume Insulation (CASA/CAD)

(ft3) Volume (ft 3)

Low-Density Fiberglass 9893.498 9729.7867 0.98345 (LDFG)

Microtherm 24.893 24.8922 0.99997

NOC-AE-1 5003220 Attachment 5 Page 32 of 40 Examining the CASA Grande automated import comparison for the STP geometry, it can be seen that all insulation type volumes have been conserved within 2%.

Insulation debris generation has been bench-marked for validation using a DEGB break at STP weld 31-RC-1402-NSS-RSG-ID-ON-SE. The CAD model Insulation debris generation values were calculated by a CAD analyst using Boolean operations available in the AutoDesk Inventor 2013 software. A side by side comparison of pictures from the debris generation calculations (for Nukon) performed in CASA Grande and by the CAD analyst is shown below for qualitative inspection in Figure 8. Notice that in both pictures (Figure 8 left and right) interference of the ZOI with piping is highlighted in red.

Figure 8: CASA Grande (left) Vs CAD (right) debris generation pictures Results for CASA Grande Vs. CAD calculated STP insulation destruction over all insulation debris types for a DEGB break on weld '31-RC-1402-NSS-RSG-1D-ON-SE' are given below in Table 2.

Table 2: CASA Grande Vs. CAD calculated insulation debris aeneration CAD Debris CASA Grande Percent Insulation Type ZOI Size Volume (W) Debris Difference Volume (ft3)

Microtherm 28.6D 0.013 1.7 197.0 7.OD 317.2 326.3 2.8 Nukon I1.9D 553.6 578.4 4.4 17.0D 810.2 829.7 2.4 7.0D 295.0 283.4 4.0 Thermal Wrap I1.9D 623.3 606.6 2.7 17.0D 1,134.8 1,138.7 0.3 All STP insulation destruction amounts calculated in CASA Grande are with 5%

of the values calculated in CAD except for Microtherm. Although the Microtherm debris generation values compared between CAD and CASA Grande

NOC-AE-15003220 Attachment 5 Page 33 of 40 calculations show a large percent difference, the magnitude of the destroyed Microtherm quantities calculated are very small in comparison to those calculated for Nukon and Thermal Wrap. Note that calculations that result in smaller amounts of calculated debris are subject to higher uncertainty inside of the CAD model (See percent difference for Microtherm in Table 2); where many of these debris are located in small penetrations and require a consideration from the CAD analyst whether they should be included or not.

A similar validation has been performed for coatings quantities using the STP model. This validation used untypical ZOI sizes but gives a comparison between CAD and CASA Grande calculated qualified coatings values. Results of the comparison are given below in Table 3.

Table 3: CASA Grande Vs. CAD calculated qualified coatings debris generation DEGB CAD CASA Abs Plant 8511 Weld Location Size Break RJD Typ e CotM9 (lb -)it Q h -)lt OQb -)

C.*t Raa Q-,()im) (ibm) (,-)

Concrete 31-RC-1402-4SSl-LSG-ID-ON-SE 31.0 4.0 Can 0.0000 0.0000 0.0000 -

31-RC- 14(0.2-S-RSG-ID-ON-SE 31.0 4.0 See IOZ 140_01 150.73 10-72 1.0766 12-RC-1221-381-8 10.126 5.0 Conre 2-2493 1.4026 .6236 12-.RC-1221-181-8 10.126 S.0 Steel IOZ 0.1017 00822 00195 00085 In Table 3 there is good agreement between the CASA Grande calculated qualified coatings debris quantities for concrete and steel at '31-RC-1402-NSS-RSG-1D-ON-SE'. Note that calculations that result in smaller amounts of calculated qualified coatings debris are subject to higher uncertainty inside of the CAD model (similar to insulation); where many of these debris are located in locations that require a special consideration for inclusion by the CAD analyst. Also note that calculated qualified coatings debris quantities can be refined by changing the area discretization parameter in the input deck for Type 2 debris.

Validation of CASA Grande debris generation routines have also been successfully performed for other plant's geometries, but have not been included in this response because consent has not been requested for their use.

Conclusions Validation of the import of STP's insulation geometry into CASA Grande has been performed by comparison to total volumes in the Appendix B developed STP CAD model for each insulation debris type. This import comparison for insulation volume conservation is automated in the CASA Grande suite and is performed at the beginning of each new simulation. CASA Grande debris generation routines for both insulation and qualified coatings destruction have been bench-marked to CAD calculated values which have shown accurate results for the STP geometry and other plant comparisons not released in this

NOC-AE-1 5003220 Attachment 5 Page 34 of 40 document. Large differences in CASA Grande vs. CAD calculated debris quantities are apparent for small magnitude debris generation. These differences may be the artifact of the CAD analyst having to perform difficult line of sight debris generation calculations inside of a CAD model. Line of sight calculations for debris generation are automated in the CASA Grande suite and are accurate up to the resolution of the imported geometry.

60. Section 5.4.3 of the submittal dated November 13, 2013, indicates that almost 100 percent of the break scenarios generate less than 10 ft3 of fiberglass debris (the probability of generating more than 10 ft3 is smaller than 10-12). Using a density of 2.4 lb/ft3 , the equivalent mass of 10 ft3 of fiber is 24 lbs (10.89 kgs). The NRC staff review of the CASA Grande program indicates that there may be a significant number of cases that generate much more than 10 ft3 of fiberglass (hundreds and up to one-thousand kg). Please clarify the meaning of Figure 5.4.5 in Volume 3, which appears to imply that the probability of generating more than 10.89 kg of fiberglass is smaller than 10-12, and clarify if this information was used in the CASA Grande model. Please clarify if the information in Figure 5.4.5 in Volume 3 also includes latent fiber.

Response

RoverD does not use cumulative distribution functions to determine the risk or deterministic failure criteria. CASA Grande is used in a non-probabilistic way, only finding the amount of fine fiber debris that is created and transported to the sump without uncertainty distributions.

The amount of fine fiber debris transported includes latent fibers and eroded fiber.

61. For breaks that are not DEGB and are assumed to have a hemispherical ZOI, please explain how are the robust barriers treated? For example, ifthe break is on a pipe near the floor and occurs on the bottom of the pipe, is the potential for damage from a reflected jet accounted for?

Response

The zone of influence (ZOI) is the volume about the break in which fluid escaping from the break has sufficient energy to generate debris from insulation, coatings, and other materials within the zone (1). The ZOI radius is dependent on the destruction pressure of a given debris source and is proportional to the internal fluid conditions and ambient conditions of containment in terms of pressure and temperature. In both spherical and hemispherical ZOI calculations, jet reflection is accounted for in the conversion of an ANSI jet to an equivalent spherical or hemispherical volume. The ZOI is representative of ANSI jet pressures and jet reflection/impingement pressures for a given break that would

NOC-AE-1 5003220 Attachment 5 Page 35 of 40 destroy specific debris sources. The ZOI boundary represents the lowest impingement pressure to cause a specific debris source to fail.

Hemispherical ZOls are utilized in the CASA Grande evaluation as an approximation for longitudinal breaks, typically from a failed weld or valve that does not result in full radial and axial offset of severed pipe ends as in the case of a DEGB. NEI 04-07 states the ZOI for longitudinal breaks can be simulated as a hemisphere with a radius determined by the destruction pressure of the insulation that would be affected by the postulated break (1). If a specific insulation fails within a 17.0D Z01 2 for example, this can be analyzed as a DEGB on pipe with inner diameter of "D" in which the ZOI is a sphere centered on the pipe axis (the break diameter of a DEGB is equal to the inner diameter "D" of the pipe). In addition, the insulation debris generated by a longitudinal break is analyzed within a hemispherical ZOI of radius 17.0D where "D" is the diameter of the break and the fiat face of the ZOI is tangent to the outer surface of the pipe. Both the spherical and hemispherical 17.0D ZOls represent the same jet pressures within a 17.0D boundary although their shape and break sizes are different.

Spherical ZOI D - break diameter = inner pipe diameter Hemispherical ZOI D - break diameter < inner pipe diameter Similar to spherical ZOls, robust barriers prevent jet expansion for hemispherical ZOls and reduce the encompassing volume of the destruction zone. All ZOIs are truncated at robust barrier interference in the CAD model which provides a visual and analytical representation of confinement to jet expansion (high energy jets cannot expand through solid structures and therefore ZOI volumes are reduced at these instances). For example, Figure 3 shows the reduction of a ZOI volume that extends beyond a robust concrete wall in the CAD model.

2 The ZOI radius is based on ANS/ANSI 58.2-1988 jet isobar mapping which determines dimensions of a freely expanding jet originating from a nozzle with diameter "D", based on ambient containment pressure of 14.7 psi, internal fluid pressure of 2250 psia, and fluid temperature of 5407F (1)

NOC-AE-1 5003220 Attachment 5 Page 36 of 40 Figure 3 - Example of ZOI truncation at robust concrete barrier From NEI 04-07 Volume 2, "the ZOI recommended in the GR [NEI 04-07 Volume 1] Section 3.4 is a spherical boundary with the center of the sphere located at the break site. The use of a spherical ZOI is intended to encompass the effects of jet expansion resulting from impingement on structures and components, truncating the sphere wherever it intersects any structural boundary or large robust equipment. The GR recommends that ZOI sizing be determined using the American National Standards Institute/American Nuclear Society (ANSI/ANS) 58.2-1988 standard for a freely expanding jet (ANSI/ANS 58.2-1988). The baseline ZOI comprises the insulation type that generates the largest ZOI of all potentially affected insulation types" (2).

Debris volumes generated from longitudinal breaks are determined by constraining the flat face of the hemispherical ZOI perpendicular to the break vector and tangent to the outer surface of the pipe. In CASA Grande, debris quantities are calculated from hemispherical ZOls with randomly sampled (for each simulated break) orientations around the pipe surface at break locations with CAD interferences. This is performed similar to guidance in NE 04-07 Volume 1, which states, "[for] hemispherical ZOI modeling, the break orientation needs to be simulated at various angles around the loop piping to determine maximum debris generation" (1). The CASA Grande risk-informed method differs from NEI 04-07 by sampling random break orientation over many break scenarios with tracked variance over the total risk solution to ensure that all contributing combinations have been sampled. This type of variance tracking ensures that all distributions, including break orientation and all user entered distributions have been properly sampled over their full ranges. If the break in question occurs on the bottom of a pipe near the floor, the boundary of the ZOI is representative of all jet reflections that occur from the break jet impingement on the concrete floor, as visualized in Figure 4.

NOC-AE-1 5003220 Attachment 5 Page 37 of 40 Figure 4 - Hemispherical ZOI example on bottom of 31" pipe REFERENCES

1. NEI 04-07 Volume 1. PressurizedWater ReactorSump PerformanceEvaluation Methodology.

Revision 0: Nuclear Energy Institute, December 2004.

2. NEI 04-07 Volume 2. Safety Evaluation by the Office of Nuclear Reactor Regulation Related to NRC Generic Letter 2004-02, Revision 0, December 6, 2004. Revision 0: Nuclear Energy Institute, December 2004.

3. ANSIIANS-58.2-1988. Design Basis for Protectionof Light Water NuclearPowerPlantsAgainst the Effects of PostulatedPipe Rupture. 58.2-88 : American Nuclear Societty, October 6, 1988.

NOC-AE-15003220 Attachment 5 Page 38 of 40

62. During review of the licensee's response to question 9 of the April 15, 2014, RAI, the NRC staff developed an additional question regarding the treatment of debris in the head loss calculation. Please clarify ifthe small and fine debris are treated as if they have the same properties in the head loss calculation (correlation)? In your response, please clearly explain how each debris size is treated?

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for head loss. Head loss is accounted for in the plant-specific deterministic testing.

63. Based on the licensee's response to ESGB question 1 .b. of the April 15, 2014, RAI, it appears that some large breaks, many medium breaks, and all small breaks do not generate enough debris to result in a 1/16-inch bed when distributed over 3 strainer trains.

Please provide the following information:

0 Distribution of low density fiberglass (LDFG) debris mass reaching the strainers for small, medium, and large breaks separately.

• The amount of latent fibrous debris that reaches the strainers for each break category and if it varies, provide the distribution and methodology used to determine the amounts.

0 The range of the mass of fine fibrous debris and small piece fibrous debris generated for each of the break categories.

a The range of the masses of these fiber categories that transport to the strainer.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for head loss. The debris distribution is accounted for in the basis for the plant-specific deterministic testing.

NOC-AE-1 5003220 Attachment 5 Page 39 of 40

64. Based on the review of the licensee's response to question 2 of the April 15, 2014, RAI, the staff has identified the following concern: what causes the variability in the head loss calculation performed by the correlation? For example, scenarios that contain apparently similar debris loads (CASA Grande Case 1 in the RAI response) may have significantly different calculated head losses. The head losses from the referenced tests represent CASA Grande values in the g 9 th percentile, indicating that almost all head losses predicted by CASA Grande are lower than the test results. The limiting CASA Grande Head loss calculation was 8.2 feet for conventional debris and 161.9 feet for total head loss, which is much higher than the test results. These maximum values seem higher than could possibly occur, at least for the total head loss. Explain if these maximum values realistic or are they non-physical predictions. Expalin why CASA Grande predicts lower head losses than the test results over 99 percent of the time.

Response

The STP risk methodology has been revised to apply RoverD (see Attachment 7) instead of using CASA Grande to generate conditional failure probabilities. RoverD is a less complex approach that relegates break sizes that generate and transport debris that is not bounded by deterministic testing to failure. RoverD does not rely on a correlation or model to account for head loss. Head loss is accounted for in the plant-specific deterministic testing.

65. RG 1.174 states that licensees are expected to evaluate "whether sufficient safety margins would be maintained if the proposed licensing basis change were to be implemented."

The NRC staff recognizes that safety margin cannot be characterized by a single number for a time-dependent analysis with multiple failure modes. Instead, it can be represented by an equation or relationship that represents the safety margin as a function of time for each of the seven GSI-191 failure modes. For example, the safety margin with respect to strainer mechanical collapse can be represented as:

Sm = 9.35 ft - AP(t)

Where Sm = margin with respect to strainer mechanical collapse AP(t) = differential pressure across strainer as a function of time Please describe whether CASA Grande calculates success with respect to each of the seven GSI-1 91 failure modes in a manner that is consistent with RG 1.174 guidance on safety margins. Specifically, please identify the failure threshold (worst allowable value) for each failure mode and state whether it is consistent with existing licensing basis calculations.

Response

The RoverD methodology (see Attachment 7) does not use CASA Grande to calculate conditional probabilities or determine failures. RoverD methodology assumes that any break that generates more fibrous debris than was represented in the testing goes to failure (core damage). The

NOC-AE-1 5003220 Attachment 5 Page 40 of 40 deterministic testing is credited with showing that there are no failures for conditions bounded by the tested configuration and debris loading. Safety margin is provided in the deterministic sense. It is comprised of the conservatism of the engineering assumptions and methodology and tested configuration (e.g., chemical effects, failed coatings, etc.). The response to the STSB RAI in Attachment 6 provides some additional information on conservatism in the analysis and testing.

66. Assumption lj of Volume 3 states that "switchover to hot leg injection would occur between 5.75 and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after the start of the event." Assumption 11 a states "the current STP design basis evaluation methodology used to calculate the required hot leg switchover timing is appropriate with the exception of GSI-191 related phenomenon." When analyzing boric acid precipitation in regards to post-LOCA long-term core cooling, the mixing volume and percentage of voids in the core used in the analyses need to be justified. Improper modeling could result in non-conservative liquid volume after a LOCA. Ultimately, this could impact the hot-leg switchover time in a plant's emergency operating procedures. STP's calculation for hot-leg switchover time following a LOCA (NC-7136, Revision 1) was provided in response to SNPB RAI 4. An input for this calculation is liquid volume in the RCS. Please provide the mixing volume and percentage of voids in the core for STP licensing basis calculations used to determine the liquid volume in the RCS for hot leg switchover timing in the calculation to validate assumptions Ij and 11 a. Please justify the use of these numbers and any assumptions made. The licensee can refer to NRC-approved methods, as appropriate.

Response

Response to this RAI will be provided in a separate submittal that includes responses to SNPB RAIs.

NOC-AE-1 5003220 Attachment 6 Attachment 6 Response to STSB Request for Additional Information

NOC-AE-15003220 Attachment 6 Page 1 of 5 NOTE: Round 2 RAI question numbers begin with the next sequential number from the April 15, 2014, RAI forthis section.

4. Back-ground: In response to NRC staff comment/question 2.4 (page 6 of 179, Volume 6.2), the licensee stated the following:

A description of how the proposed change will affect the technical specifications is provided in Regulatory Evaluation Section 4.1.3 in the LAR provided in Enclosure 3. As discussed in more detail in Enclosure 3, no changes to operability requirements for affected systems and no changes to the existing technical specification Action Statements are proposed. Proposed changes to the technical specification bases that conform to the changes in the licensing and design bases are included in Attachment 3 to Enclosure 3 for staff information.

Page 1 of 1 of Attachment 3 to Enclosure 3 of the licensee's letter dated November 13, 2013, "Technical Specifications Bases Page Markups," states, in part:

UFSAR Appendix 6A provides a risk-informed approach that addresses the potential of debris blockage concluding that long-term core cooling following a design basis loss of coolant accident is assured with high probability. UFSAR Appendix 6A also provides guidance for assessing the potential impact on Operability due to unexpected material such as loose debris discovered in containment that may contribute to debris loading on the strainers.

Page 15 of 16 of Attachment 2 to Enclosure 3 of the licensee's letter dated November 13, 2013, "STPEGS UFSAR Page Markups" states, in part, the following:

The table provides guidance that may be used to immediately assess the potential impact due to unexpected material discovered in containment that may contribute to debris loading on the strainers. As discussed in Reference 6A-4 [licensee letter dated June 19, 2013], these values are not necessarily the limiting amount of each type as analyzed.

Conservatisms in the reported values are also discussed in Reference 6A-2 [licensee letter dated December 11, 2008]. Therefore, a condition that may exceed the values shown in the table does not preclude reasonable expectation of operability.

Debris Type Input Parameter (Reference 6A-6) Value Minimum Margin Latent debris, consisting of: 200 Ibm (Total) 40 Ibm (Total)

- Dirt and/or dust 170 Ibm (1.0 cubic ft) 34 Ibm (0.2 cubic ft)

- Fiber, e.g., fibrous insulation 30 Ibm (12.5 cubic ft) 6 Ibm (2.5 cubic ft)

Miscellaneous debris, including but not 100 sq-ft 10 sq-ft limited to unqualified tags and labels Unqualified coatings Table 6.1-4 100 sq-ft

NOC-AE-1 5003220 Attachment 6 Page 2 of 5 Due to the complexity of the analysis, the potential exists for conditions to be discovered which may not be represented by the values in the table, and for which evaluations would be required to evaluate the impacts [ ].

Page 26 of 31 of Enclosure 3 to a letter from STPNOC dated November 13, 2013, states, in part, the following:

When warranted, an immediate operability determination will be followed by a prompt operability determination that will apply additional information and supporting analyses to confirm the immediate operability determination. Evaluations may consider additional information provided in the inputs to the CASA Grande analysis as well as the identified conservatisms associated with the categories of major assumptions in the CASA Grande analysis, Section 3 of Volume 3 (Enclosure 4-3).

For a discovered condition that potentially affects debris quantities in containment, the applicable CASA Grande input parameters and assumptions provide a means for immediate operability determinations and follow-up determinations, as warranted, to evaluate the impact on containment sump performance.

Concern: It is the NRC staffs position that when evaluating operability of an SSC, the use of risk assessment or probabilities of occurrence of accidents or events is unacceptable. The definition of operability is that the SSCs must be capable of performing their specified safety function or functions. This inherently assumes that the event occurs and that the safety function or functions can be performed. Operability is not indeterminate. An SSC required to be operable must be able to perform its specified safety function or it is inoperable.

The NRC staff is concerned that the CASA Grande design inputs (parameters and assumptions) referred to in Reference 6A-5 of the UFSAR Markup includes probability aspects the licensee proposes to be acceptable to be used during an operability determination if a condition is discovered that potentially affects debris quantities in containment and the need arises for evaluating the impact on containment sump performance.

NOC-AE-1 5003220 Attachment 6 Page 3 of 5 Request: provide the following additional information:

1) An explanation of how the assumptions referred to in Reference 6A-5 of the UFSAR Markup and discussed in Section 2.2 of Volume 3 of the same document will be used during an operability determination. Please include an example to the extent practical.

2) If the licensee is proposing to allow the use of risk information in the assessment of operability, then:

a. Please provide a description demonstrating the relationship between probability and operability for each of the assumptions discussed in Section 2. 2 of Volume 3.

b. Please explain how would the probability of occurrence of each of the assumptions discussed in Section 2.2 of Volume 3 change to improve or degrade the impact on containment sump performance.

Response

As discussed in a public meeting with the NRC staff on February 4, 2015, STPNOC plans to propose a change to the TS for ECCS and for CSS to add a LCO and action statement specific to debris effects. The operability requirement for the LCO will be based on the quantity of debris in the STP debris analysis and operability determinations will not involve application of probabilistic risk.

As presented in the meeting, STPNOC is in the process of revising its risk-informed GSI-191 pilot licensing application to implement a much less complex "Risk over Deterministic" (RoverD) methodology. RoverD will form the technical basis for the proposed change to the TS.

In RoverD, the effects of debris that are bounded by the plant-specific testing are deterministically mitigated in accordance with NRC-accepted methodology for resolution of GL 2004-02. By applying pipe break frequencies from NUREG 1829, STPNOC shows that the risk associated with debris from pipe breaks that generate quantities of debris that are not bounded by plant-specific prototypical testing is very small, in accordance with the acceptance criteria of RG 1.174. The break locations that can generate debris outside the assumed test conditions are RCS breaks in the pressurizer surge line and RCS loop piping. Defense in depth and safety margin in the testing and calculation assumptions provide reasonable assurance that the sump strainers can perform their support functions for ECCS and CSS even for the debris generated from these larger breaks. More detail with regard to RoverD is provided in Attachment 7.

NOC-AE-15003220 Attachment 6 Page 4 of 5 The LCO for the change to the TS will be based on the amount of debris in the STP debris analysis. The draft LCO presented in the February 4, 2015, meeting read:

Reactor Containment Building emergency sump shall be OPERABLE by limiting the containment debris quantities to be less than or equal to the STP debris analysis assumptions.

The operability determination for a potentially degraded or nonconforming condition would involve evaluation of the quantity, nature and transportability of the debris in question to determine if it is within the STP debris analysis. It does not involve a risk assessment.

The specific items listed in the RAI are discussed below. Except for the LOCA frequency assumptions, which will be removed as a factor in the operability determination, they are assumptions that are typical in engineering analyses and which often have conservatisms that can be used for margin in an operability determination.

1. General assumptions

2. Equipment failure assumptions (prior to start of recirculation): To the extent that these are used to establish the quantity of debris assumed in the plant-specific testing, they could be used to identify margin.

3. LOCA frequency assumptions: This would not be applied in the operability determination and will be removed from the list.

4. Debris generation assumptions: There are assumptions in the modeling for how much debris is generated at various locations which are related to physical conditions such as credit for presence of physical barriers to break effects. These are not related to the risk and could possibly be revised to reduce the amount of debris assumed to be generated and provide additional margin.

5. Chemical effects assumptions: These assumptions are not related to the risk evaluation. The plant-specific testing used WCAP-16530 to determine the debris quantities for the test. Other STP testing has shown that STP has very little chemical effect. With less assumed chemical effects on head loss, the strainers can handle more debris.

There is significant margin that can be applied in an operability determination.

6. Debris transport assumptions: These assumptions would generally be applied to determine if an identified condition involves debris that is transportable. If it is not transportable, then it generally should not be of concern. There may be some conservatism that can be applied on a case-by-case basis. There is no PRA/risk element for this type of evaluation.

7. Head loss assumptions: The debris head loss used for NPSH is based on test results. Conservative assumptions for the NPSH determination include maximum sump temperature, minimum sump

NOC-AE-1 5003220 Attachment 6 Page 5 of 5 water level, maximum pump flow rates, and conservative calculation of the clean strainer head loss.

8. Degasification assumptions: Vortexing, air ingestion, and void fraction are addressed separately as its own issue. As shown by testing, the PCI designed strainers are not subject to vortexing issues even with a very low submergence. Vortex breakers are installed in the sump pit. Void fraction is not a concern based on conventional hydraulic and fluid flow calculations.

9. Penetration assumptions: Fiber penetration is a measured value and measurement uncertainties are included in the evaluation. There is no PRA/risk element associated with this parameter.

10. Core blockage assumptions: The evaluation assumes the core and bypass flow is fully blocked for all small breaks and all hot leg breaks.

It is assumed that < 15 g/Fuel Assembly will provide adequate cooling for medium and large cold leg breaks. This is a conservative assumption that could be reviewed for margin in an operability determination.

11. Acceptance criteria assumptions: All of the factors above generally feed into acceptance criteria.

NOC-AE-1 5003220 Attachment 7 Attachment 7 Description of the Risk over Deterministic (RoverD) Methodology

NOC-AE-1 5003220 Attachment 7 RoVERD:

USE OF TEST DATA IN GSI-191 RISK ASSESSMENT List. of contributors and affiliation Edition date, tine - Saturday 1 4 th March, 2015, 07:39 CONTRIBUTOR(S) AFFILIATION CONTRIBUTION Steve Blossom STPNOC Project Manager, GSI-191 project Ernie Kee STPNOC Author &, ROVERD concept, STPNOC technical lead Alex Zolan and John the University of Texas at LOCA frequency, strainer penetration review and anal-Hasenbein Austin ysis Fatma Yilmaz STPNOC LOCA Frequency review W*ayne Harrison and STPNOC Regulatory compliance review Drew Richards Rodolfo Vaghetto Texas A&M University RCS Thermal-Hydraulics Phil Grissom Southern Nuclear Co. RovERD impact on Option 2b plants David Imbaratto Pacific Gas & Electric ROVERD impact on Option 2b plants Bruce Letellier and Alion Science and Technology CASA Grande results for real size and location Jeremy Tejada Seyed Reihani University of Illinois at Oversight review Urbana-Champaign Vera Moisetytseva YK.risk, LLC Oversight Review

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Contents Contents ii 1 Introduction 1 2 RoverD risk quantification summary 3 3 Reactor containment building debris generation and transport 4 4 LOCA frequencies 9 5 RCS Thermal-hydraulics 16 6 Core performance metrics 17 7 Application 18 8 Weld list 19 9 Acronyms 49 10 LDFG mass conservation solution implementation 51 11 Top-down LOCA frequency solution implementation 68 List of Figures 1 The two basic elements of ROVERD are separating scenarios into risk-informed or deterministic categories and then subsequently evaluating the risk ....... 2 2 Flow paths through the containment and reactor vessel following the start of ECCS recirculation showing where fiber mass (in) is conserved (ECCS strainers, ECCS sump, and the reactor core) ..... .................. 4 3 Simplified arrangement of the reactor system, ECCS and CSS with flow di-rections shown during normal operation for the intact plant and flows in the emergency systems when demanded. The arrangement has been distorted so the flows and equipment can be seen. Shown as well are flow paths from hypothesized breaks out to the ECCS sump ......................... 5 4 Flow network for the three STP ECCS and CSS trains showing the three places debris is caught: the pool, the strainer, and the core during a CLB scenario. Shown as well are the various flow splits that take place between the places debris is caught. The flow split A is defined by the amount of flow demanded by the core to remove decay heat ....... .................. 6 Saturday 14 1h March, 2015, 07:39 ii corresponding: keeejUbstpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 5 Filtration efficiency fits as a function of mass compared to measured data for the STP ECCS strainer modules. Efficiency fits obtained for the upper, central, and lower limits of the measurements are compared to the measured data ............ ......................................... 8 6 Comparison of bounding cases for core LDFG accumulation after start of ECCS recirculation. The mass accumulation should be divided by 193 to obtain gm/FA .......... ................................... 10 7 The top down approach assigns equally-weighted frequency in intervals be-tween pipe diameter extents. As DsmaII becomes larger, the total number of welds in successive categories decreases ....... ..................... 11 8 Using linear interpolation or log-linear interpolation of NUREG 1829 data (Tregoning et al., 2008) produce different inter-point interpolation behaviors on different graph formats ......... ............................ 12 9 Process for establishing risk thresholds depending on whether an acceptable test has been previously performed or if one should be designed to achieve a specific risk goal.......... ................................. 19 List of Tables 1 Example of the first few flows that would result from a decay heat load in a 40K MWd/MTU exposure assuming 3853 MW operation history ......... 7 2 Core mass accumulation for bounding cases of initial ECCS sump pool fiber concentration Cp(t = 0) and upper and lower bounds of filter efficiency. . . 9 3 NUREG-1829 (Tregoning et al., 2008, Table 7.19) for the mean, median, 5th percentile, and 95th percentile exceedence frequency values for current-day estimates STP PRA break sizes for small, medium and large LOCA are, less than 2 in (small), 2 in to 6 in (medium), greater than 6 in (large) ...... ... 12 4 Case 1 and Case 2 results for geometric (GM) and arithmetic (AM) aggre-gations of Tregoning et al. (2008, Tables 7.11 and 7.19) data. Frequencies are in events/yr. Also shown are the results for a DEGB-only model for the locations that go to failure ......... ............................ 15 5 ALERF evaluation for geometric and arithmetic means of the Continuum and DEG-only models ......... ............................... 16 6 Summary of boundary conditions and assumptions of the STP core blockage analyses ............. ...................................... 17 7 Results of blockage scenarios showing scenarios that had PCT less than 800'F (Pass) and those that exceeded 800'F (Fail) .................... 17 Saturday 1 4 th March, 2015, 07:39 iii corresponding: keeej(_Ustpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 8 Data for weld locations in the risk-informed category listing the ith weld number, mass of fiber in the sump for the scenario (lbm), location name (ID), Break size (Size), scenario frequency, fi (mean quantile, geometric aggregation), Category, and NUREG 1829 data category ............... 20 9 DEGB data (largest break size) for weld locations in the deterministic cate-gory showing listing the ith weld number, the margin to the mass of fiber in the sump produced to the tested amount (Ibm), location name, Break size (Size), scenario DEGB frequency, fi (mean quantile, geometric aggregation),

and NUREG 1829 data category ........ ........................ 21 10 Single train data for weld locations in the risk-informed category listing the ith weld number, mass of fiber in the sump for the scenario (lbm), loca-tion name (ID), Break size (Size), scenario frequency, f t (mean quantile, geometric aggregation), and NUREG 1829 data category ............... 34 11 Single train DEGB data (largest break size) for weld locations in the de-terministic category showing listing the ith weld number, the margin to the mass of fiber in the sump produced to the tested amount (lbim), location name, Break size (Size), scenario DEGB frequency, fi (mean quantile, geo-metric aggregation), and NUREG 1829 data category ..... ............ 36 Listings 1 Source listing for (1c) solution, Alex Zolan, UT Austin, 02 March, 2015 . 52 2 Mass conservation solver, time-dependent inputs ..... ............... 63 3 Input listing for the mass conservation solver: constants for High Pool Con-centration, High Filtration Efficiency ........ ...................... 64 4 Input listing for the mass conservation solver: constants for High Pool Con-centration, Low Filtration Efficiency ........ ...................... 65 5 Input listing for the mass conservation solver: constants for Low Pool Con-centration, Low. Filtration Efficiency ........ ...................... 66 6 Input listing for the mass conservation solver: constants for Low Pool Con-centration, Low Filtration Efficiency ........ ...................... 67 7 Source listing for (5) solution, Alex Zolan, UT Austin, 27 February, 2015 . . 68 8 Input listing for the Arithmetic Means quantiles. Taken from NUREG-1829, Table 13 ............. ...................................... 71 9 Input listing for the Geometric Means quantiles. Taken from NUREG-1829, Table 19 ............. ...................................... 72 10 Input listing for the welds in the scope of GSI-191 ...... .............. 72 11 Input listing from the ROVERD fetch stage for the welds in the scope of GSI-191 ............. ...................................... 72 Saturday 14 th March, 2015, 07:39 iv corresponding: keeej.stpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 1 Introduction ROVERD is a method that follows the guidance of NRC (2011) to assess the risk associated with concerns raised in GSI-191. ROVERD uses test data and NRC (2011) guidance to evaluate the magnitude of LOCAs required to exceed a performance threshold that is established by testing for effects again associated with concerns raised in GSI-191. The performance threshold is set low, set to underestimate the true level where functionality may be lost, so that risk for strainer failure is overestimated. Even when adopting a low performance threshold, the risk is shown to be very small (NRC, 2011).

ROVERD separates the risk estimate into two categories of scenarios designated as 'de-terministic' and 'risk-informed' as illustrated in Figure la. The deterministic scenarios are those in which the LDFG fiber fines estimated to arrive in the ECCS sump following LOCA are equal to, or less than, the amount of fines used in acceptable strainer testing. The limit is set using testing methods intended to determine the maximum ECCS strainer head loss for the tested condition. For example, single failure criteria are adopted in combination with conditions known to overestimate head loss such as chemical quantities and morphol-ogy, strainer flow rate, and particulate amounts that includes mechanical processing of fiber. If the strainer performance test shows a LOCA scenario will not cause any strainer performance requirements to be exceeded, then that scenario will not result in failure and is categorized as deterministic as shown in Figure la.

The term 'acceptable testing' refers to so-called deterministic tests performed under circumstances that would not be realized in a design basis accident as mentioned above.

Such tests can be used to establish a bounding envelope of performance (low performance threshold) for the realistic scenarios realized or hypothesized. Using test data that includes unrealizable circumstances may result in scenarios that would fall outside the bounding envelope defined by such test data. The risk for any such scenarios is required to meet a

'very small' threshold as shown in Figure lb.

In the following, the various analyses required to complete a ROVERD assessment are summarized. The steps required to complete a ROVERD analysis are summarized in Sec-tion 2. Section 3 summarizes the way ROVERD fiber generation, transport, erosion, and latent fiber quantity are established. Section 4 summarizes the LOCA frequency deter-mination for scenarios in the risk-informed category. The basic approach uses top-down frequency partitioning. In-vessel analyses are described in Section 5 including blockage analyses for HLB and CLB (scenario success criteria), fuel fiber limits, boric acid pre-cipitation. Core performance metrics must be met in addition to strainer performance.

Section 6 summarizes evaluation of core performance metrics.

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NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages (a) ROVERD separates those scenarios that go to success deterministically from those that are assumed to go to failure and require risk-informed analysis Scenarios to be  ? ,ob:IuI evaluated for risk a (Use PRAand RG1.174)

(Scenariosare assumed to go to coredamage) Yeses

[CDCADF F Both in {CDFACOF)

ILERFALERF] o No LERF 1E-OS Unacceptabl Mitigation ACDF No test with greater In111amount Rgim of LDFG fines included Yes Run PRA for CDF and LERF (b) Flow chart showing the ROVERD evaluation process following categorization of scenarios to determine risk acceptability. In this depiction, the frequency, fi, of break at any location is determined by the diameter as determined in NUREG 1829.

Figure 1: The two basic elements of ROVERD are separating scenarios into risk-informed or deterministic categories and then subsequently evaluating the risk.

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NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 2 RoverD risk quantification summary ROVERD involves the following steps to assess the risk associated with the concerns raised in GSI-191:

1. Perform a test that has some margin to failure following accepted protocols (see AREVA, 2008)

Note the amount of fine tested (in this case, 191.78 lbm) as well as the configura-tion (in this case, two ECCS trains). The plant configuration is important to ensure whether the test bounds other plant states. Fine fiber is used because it is the trans-portable form of the LDFG created in the break scenario Note that the test results must be applied to strainer performance criteria to ensure they are met using deterministic analysis requirements (e.g., vortexing, structural margin, flashing, etc.)

2. In-vessel performance criteria (core cooling, including fiber effects, boric acid precip-itation) must be met under the conditions tested

3. Run CASA Grande to itemize all break locations, break sizes, and amount of LDFG fines in the sump (including erosion and latent fiber)

4. Compare the amount of fiber fines in each break scenario to the tested amount (AREVA, 2008)

If the amount is equal to or less than the tested amount, categorize the scenario

'deterministic'.

If the amount exceeds (that is, 'over') the tested amount, categorize the scenario

'risk-informed'

5. Evaluate the risk contribution (including in-vessel) of scenarios in the risk-informed category against the Regulatory Guide 1.174 quantitative criteria for {CDF,ACDF},

{LERF,ALERF}

Assign change in core damage frequency to the frequency from (5)

Check {CDF,ACDF} against the quantitative requirement of Regulatory Guide 1.174, Region III Check {LERF,ALERF} against the quantitative requirement of Regulatory Guide 1.174, Region III Verify other requirements (for example, safety margin, defense in depth) of Regula-tory Guide 1.174 are met

6. If all requirements are met for the risk-informed category, the performance is accept-able Saturday 1 4 th March, 2015, 07:39 3 corresponding: keeej 3cstpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages YACore Cold leg Cold legs

ý, - , - DD.... .

W7 S--B A I- 1_-.. ..

QA Flow out of

• the RCSBreak (a) Fiber flow paths for a three train plant (trains A, (c) Conceptual illustration of B, and C) in containment af- (b) Fiber flow paths through three zones of destruction poten-ter ECCS recirculation show- the reactor vessel following tial within the ZOI showing how ing flow splits, -y, between ECCS recirculation showing the the debris distribution shifts to-total ECCS injection and additional flow split (A) to the wards larger sizes further from the ECCS core and the break break Figure 2: Flow paths through the containment and reactor vessel following the start of ECCS recirculation showing where fiber mass (m) is conserved (ECCS strainers, ECCS sump, and the reactor core) 3 Reactor containment building debris generation and transport NEI (2004) documented an acceptable methodology for determining the amount of debris generated in a LOCA of any particular size by defining a ZOI. Within the ZOI, specific size distributions of LDFG particles can be estimated using acceptable methods (Figure 2c).

The amount and type of each debris species transported to the ECCS sump is gov-erned by logic trees developed to estimate the amounts captured and sequestered, and the amounts that would continue to transport (for example see NEI, 2004, ppg 3-45, 3-53).

ROVERD uses a 'worst case' set of assumptions in development of the STP debris transport logic tree.

The flow paths through the RCB with the water flowing out of the breach in the RCS as well as with water from sources such as ECCS and CSS during the recirculation phase are shown in Figures 2a and 2b. CASA Grande performs mass conservation of debris species in the containment pool (Mp), on the ECCS strainers, (Mi) and in the reactor core, (Mc),

(Figure 4). Although different size particles are created from partially destroyed fiberglass insulation strands within the ZOI (Figure 2c), the smallest particles that transport readily through the RCB are 'fines'. Larger and partially destroyed LDFG insulation either do not transport or quickly sink in the ECCS sump and remain there. Over time, water flowing through the RCB tends to erode some of the larger particles captured outside of the ECCS sump into fine particles. Besides LDFG either destroyed or eroded into fine particles, fine Saturday 14 1h March, 2015, 07:39 4 corresponding: keeej(Qstpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages particles from tramp dust and dirt need to be taken into account.

A break size and location define a scenario from which is derived the amount of LDFG fines that arrive in the ECCS sumps. The methodology for examining many thousands of possible break sizes, orientations, truncation of ZOIs, transport of fines, and erosion of LDFG requires a computational framework implemented on a computer (Letellier et al.,

2013, for example).

Figure 3: Simplified arrangement of the reactor system, ECCS and CSS with flow directions shown during normal operation for the intact plant and flows in the emergency systems when demanded. The arrangement has been distorted so the flows and equipment can be seen. Shown as well are flow paths from hypothesized breaks out to the ECCS sump.

A flow network that approximates the transport and capture of debris in containment in a CLB is shown in Figure 4. The primitive data for this system are: (1) time-dependent flows Q,(.) and Qc(-), (2) scalars Vp, Mp(0), and -y. The flows are time-dependent due to the influence of Q, on A. Qc as a function of time is obtained from a table and is governed by the decay heat level. Table 1 lists the first few entries in the table. Given these model primitives, an analysis of the time-dependent accumulation of debris on the strainer, core, and in the pool can be performed. These functions are governed by a set of non-linear differential equations. The non-linearity arises due to the filtration function, as shall become apparent in the following.

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NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Each strainer removes fiber according to filtration functior Figure 4: Flow network for the three STP ECCS and CSS trains showing the three places debris is caught:

the pool, the strainer, and the core during a CLB scenario. Shown as well are the various flow splits that take place between the places debris is caught. The flow split A is defined by the amount of flow demanded by the core to remove decay heat.

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NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Table 1: Example of the first few flows that would result from a decay heat load in a 40K MWd/MTU exposure assuming 3853 MW operation history.

Hour Flow Hour Flow (gpm) (gpm) 0 2141.1 0.0125 1467.4 0.0025 2141.1 0.015 1401.1 0.005 1964.3 0.0175 1352.5 0.0075 1718.6 0.02 1314.1 0.01 1564.8 0.0225 1281.8 3.1 Mass conservation The transportable debris from the hypothesized LOCA moves down into the containment emergency sump forming a pool of water (Figure 3). The initial concentration of debris in the containment emergency sump water pool is Cp(O) =ý(0) At the start of the ECCS recirculation phase, we assume all the transportable debris is in the pool. Hence, there is none on the strainer or the core (.AIs(O) = 0 and MA(O) = 0). The rate of accumulation of the debris on the strainer and the core is almost entirely governed by the amount by the amount of fiber that penetrates the strainer and is subsequently transported to the core as a result of the core flow rate. The governing conservation equations are:

d- " (t) = Q (t) Cp (t)f (MA/,,(t),(a (ka) dt .A' St ( @Q() (1a) 0 d, sd +dk(t),

-tk (lc) d i(t) + (t) +

k where k is the strainer index. Wherever k appears the index is taken over all the values in

{A, B, C}, i.e., the three strainers. The initial conditions and boundary conditions are:

1. f(MA) is a fraction between 0 and 1 Figure 5, dependent on the amount of mass on the strainer (Ogden et al., 2013, Figure 13)',

1 Ogden et al. (2013) used test data from measurements performed on one of the 20 strainer modules in each STP ECCS train. As a consequence, the data must be scaled to the full strainer area (scaled by a factor of 20) when applied to the full plant.

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NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

2. Q,(.) should be treated generally as a function of time to model pumps turning on and off (discrete tabular function),

3. Q,(.) is a known function of time (discrete tabular function based on decay heat demand),

4. Vp is a given constant value for any particular scenario,

5. The initial mass on the core is Mc(O) = 0,

6. The initial mass in the pool, Mp(O), is given,

7. And Cp(t) = Mp(t)/Vp.

0.95 0.9

• Test 1: 353gpm N Test 2: 353gpm 0.85 0/Test 3: 353gpm 0.8 Test 5: 358gpm 0.75 7: 220gpm sTest 0Fit 0.7 -Upper Envelope

-Lower Envelope 0.65 0.6 0.55 . .. ..

0 500 1000 1500 2000 2500 3000 3500 4000 Strainer Mass In Grams Figure 5: Filtration efficiency fits as a function of mass compared to measured data for the STP ECCS strainer modules. Efficiency fits obtained for the upper, central, and lower limits of the measurements are compared to the measured data.

3.2 Results (la) to (1c) were integrated in an application that uses well-known ordinary differential equation solvers 2 implemented in a Python application to obtain Mc(t) (Listing 1). The 2

"lsoda" from the class, scipy.integrate.ode, is implemented. From the scipy.integrate.ode documenta-tion: 'Real-valued Variable-coefficient Ordinary Differential Equation solver, with fixed-leading-coefficient 8 corresponding: keeej@stpegs.com March, 2015, 07:39 1 4 th March, 2015, 07:39 Saturday 141h 8 corresponding: keeej(gstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages application is designed to provide solutions for different initial conditions and boundary conditions supplied in simple text files. The application is fully described in Section 10 with code listing and input files.

The amount of fiber bypassed to the core is primarily dependent on the initial sump pool concentration, Cp(t = 0), the filtration efficiency, f(.), and the decay heat demand, Qc(t) which is a fixed function of time. The pool concentration is defined by the amount of LDFG arriving in the ECCS sump pool for each Dý7au and the pool volume. The filtration efficiency is based on data with uncertainty (Figure 5).

Uncertainty associated with the variables, Cp(t = 0) and f(-) is evaluated by looking at lower and "upper bound" values for the variables. The minimum amount of LDFG fines in all the risk-informed scenarios is approximately 192 lbm Table 8 (the amount tested).

Assuming the total amount of LDFG transported to the sump is double the amount of fines, an upper bound for fiber mass in the pool for risk-informed scenarios would be about 550 lbm (note that smalls don't fully transport to the strainer). A reasonable upper pool volume limit is approximately 550,000 gal and reasonable lower limit is approximately 300,000 gal.

Table 2: Core mass accumulation for bounding cases of initial ECCS sump pool fiber concentration C,(t =

0) and upper and lower bounds of filter efficiency.

Cp(t = 0) gm/GAL lower:f(M1(t = 150 min.)) upper:f(M (t = 150 min.))

High (0.832) 441 247 Low (0.158) 400 241 4 LOCA frequencies In general, the ECCS strainer may operate under several different plant states. Most of the plant states tested will be congruent with deterministic assumptions on train availability (plant states). In the risk-informed category of ROVERD, scenarios associated with plant states not tested would be relegated to failure, or could be assessed for risk based on their risk contribution in a way similar to the states tested. Because different plant states may need to be evaluated, depending on details associated with the test used in the ROVERD assessment, an additional step may need to be taken to account for plant states not tested.

implementation. It provides automatic method switching between implicit Adams method (for non-stiff problems) and a method based on backward differentiation formulas (BDF) (for stiff problems).'

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NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 450 400 350 200 ISO _

Low Concentration High Filtration 15 Low Concentration, Low Filtration 100 High Concentration, Low Filtration so High Concentration, High Filtration 0

0 5 10 1s 20 25 30 3s 40 45 50 Time after Redrculatlon (min)

Figure 6: Comparison of bounding cases for core LDFG accumulation after start of ECCS recirculation.

The mass accumulation should be divided by 193 to obtain gm/FA.

4.1 ACDF frequency determination A fundamental goal of the RoverD approach is to determine the total frequency of breaks that fall into the risk-informed category. In a preprocessing step known as RoverD's fetch stage, CASA Grande runs are performed to identify all weld locations, with corresponding break sizes, which produce more than the allowable amount of fiber fines.

With fetch completed, ROVERD has data that can be thought of as ordered pairs consisting of a weld index and a break size. For now, assume that I weld locations are in the risk-informed category and these locations are indexed by i = 1, ... , I. Each weld location i then has a corresponding break size Dýmau which caused it to be placed in the risk-informed category. It is possible that for a single weld, multiple break scenarios caused it to be put in this category. If so, define D-smal to be the smallest such break size.

Now, recall that the goal is to determine the overall frequency of events that generate too many fiber fines. Two primary principles are adhered to in order to obtain the top-down frequency:

1. In the limiting case for which every weld and every break above x is considered "bad" (that is, at that break size, more fines come to the sump than were tested), 4I should equal to f(x), the NUREG 1829 exceedence frequency at x,

2. In the top-down method, ROVERD should depend on the number of welds in the ROVERD fetch file, for any (fixed) plant. In particular, 4 should increase if welds are added to the set of "bad" welds.

10 corresponding: keeej@stpegs.com Saturday Ih March, Saturday 1144 th 2015, 07:39 March, 2015, 07:39 10 corresponding: keeejUstpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages f~~N1Rk(3l82~ Pip.eSL. I1 Pip. Si- 2-

- Pip. Sit. 3- - 0 0 Pip.Site N SmutaWeld 3TotalWelds 10101.1Welds A0=o0.5) le Z 0ý AD,_- P 0, }1 I'), 1) NUREG1829"d eite Figure 7: The top down approach assigns equally-weighted frequency in intervals between pipe diameter extents. As D.!""'11 becomes larger, the total number of welds in successive categories decreases.

For each weld i in the risk-informed category the goal is to determine the frequency of breaks that exceed DjýmI. This is called F(Ds"11) and is the frequency of unacceptable events caused by that particular weld. Then, the overall frequency of unacceptable events caused by breaks in the risk-informed category is simply the sum of these frequencies:

I 4,

• F(D,small))

In general, as shown in Figure 7, interpolation is required to obtain frequencies at break sizes, Dsmall, and pipe diameters other than the data in Table 3. Because the Tregoning et al. frequency data 'fall off' so quickly as break size increases, two methods are reviewed, linear-linear and log-linear (Figure 8).

The log-linear method interpolates for the frequency at break size x in the interval a and b with the log of the frequencies, Oa and kb which appears to be a more natural fit in a log-linear presentation (Figure 8a):

ox = 0l9oa (0l0bl9oaT (2)

The linear-linear method is interpolates frequency (41) linearly at x (break size) val-ues. Of course, it appears to be a natural fit between data in a linear-linear presentation Saturday 1 4 th March, 2015, 07:39 11 corresponding: keeejLastpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 1.8-06 1.01[-05 1.64-06

• NURFG 1829

• NUREG1829 UerInterpolflor Un 110-06 - Lig- I,.,ntrlatmI0

• Log-linea, InterplOOaln LOE-O F 102E-06 I OFM0 Lg*fi I.W'at 6,0E.ý07 400E-07 4,0E-07 2.00-07 o.oE.00 I100-05 10 is 20 25 30 35 0 5 10 15 20 25 30 35

$"Si..(in) B,.a6 5i. W6, (a) Example data at the upper NUREG 1829 (b) Example data at the upper NUREG 1829 break sizes shown in a linear plot format (linear- break sizes shown in a log-linear plot format (log-linear interpolation data form a straight line be- linear interpolation data form a straight line be-tween data points) tween data points)

Figure 8: Using linear interpolation or log-linear interpolation of NUREG 1829 data (Tregoning et al.,

2008) produce different inter-point interpolation behaviors on different graph formats.

(Figure 8b):

¢. = C. + (¢b - C.)(x -a)

(b- a) (3)

Table 3: NUREG-1829 (Tregoning et al., 2008, Table 7.19) for the mean, median, 5th percentile, and 95th percentile exceedence frequency values for current-day estimates STP PRA break sizes for small, medium and large LOCA are, less than 2 in (small), 2 in to 6 in (medium), greater than 6 in (large).

NUREG-1829 Values Category Break Size (in) 5th Median Mean 95th cat, 6.80E-05 6.30E-04 1.90E-03 7.10E-03 cat 2 15 5.OOE-06 8.90E-05 4.20E-04 1.60E-03 8

cat 3 3 2.14E-07 3.4E-06 1.6E-05 6.1E-05 cat4 7 1.4E-08 3.1E-07 1.6E-06 6.1E-06 cat 5 14 4.1E-10 1.2E-08 2.OE-07 5.8E-07 cat6 31 3.5E-11 1.19E-09 2.9E-08 8.OOE-08 To explain the calculations, we first focus on a particular weld from Figure 7. In par-ticular, we examine Weld 5 in a pipe of category 1, which is denoted by D 1. To determine F(Dsmal), the goal is to be consistent with NUREG-1829. Any particular quantile value in Table 3 may be used as the basis. For example, the PRA LOCA initiating event frequencies are based on the mean value. Let f(Dmaii) be the exceedance frequency for a break of size Saturday 1 4 th March, 2015, 07:39 12 corresponding: keeej(@stpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages D""ll as implied by a selected quantile value in Table 3. In general, such a quantity must be interpolated from the values in the NUREG-1829 categories.

Plant-wide, the frequency of breaks of size D"mall and larger is f ( D5mt)

Shown down the right side of Figure 7 are categories defined by increasing pipe sizes.

We define Cat(Dsmall) as 0 < D1 < D 2 < ... < Dy- 1 < Dmall < Dj ... < Dn-1 < ]IJn, Cat(D~ifatl) = j. Every weld that can experience a break of size D"7 att or larger contributes to the overall frequency. Hence, it is deduced that:

F( Dmatt -- (Pmall)

F( - f(Dl)a(D )

TW 1 '

where T1,17 for pipe size n is the total number of welds in pipes of this category or larger.

For a pipe in category 2, the calculation is similar. However, it should be noted that the denominator in the equation above depends only on the size of. the break and not the category of pipe in which the weld resides. So, for Weld 7 in pipe category 2, D is smaller than DIl1. In this case, the frequency of a break of size Dsmau is F(Dsnhau)- f (Dýmall)

TW, For Weld 11, it is

,a f(Dsmall)

F(D11) -- TW72 Now for any weld i in pipe category n with a smallest break size Dsinal2 a general formula can be written:

fDsaul g(Dsnall) f (D? (4)

TWCat(Dsm-U)

Cat(D smail) is the pipe category corresponding to Dý"" . For example, if Category 1 is 1-inch pipes and category 2 is 2-inch pipes, then for a break of 1.75in, Cat(1.75in) = 2.

Now, let Rn be the set of all welds which are in the risk-informed category and are associated with pipes of category n. Then, the frequency of unacceptable events due to weld breaks in pipes of category n can be written as:

y*F(DimU) iER, Finally, the overall frequency of events in the risk-informed category is given by:

NP I

= z z F(D7ml)"

n=l iER, (5)

Saturday 1 4 th March, 2015, 07:39 13 corresponding: keeejOUstpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 4.2 Plant states not tested Single ECCS/CSS train operation is not assumed in a deterministic STP LOCA evaluation.

However, in a risk-based assessment, single train operation is possible and for certain scenarios, single train operation is assessed to go to success in the PRA. In the STP ECCS design, single train operation would result in twice the debris load on the operating strainer. Therefore, the breaks that could be tolerated would be those with one half the tested (two-train operation) debris load.

The break frequency description above would apply in the same way to the single train operation, but would clearly result in higher frequencies due to the increased debris load.

To account for the increased risk, (5) could be assessed for the cases where two or three trains are operating (cases either tested or bounded by the test) and assessed again for the untested case (single train operation) with the higher frequency. For example, if f2 is the success frequency for two or more trains operating and f, is the success frequency for single train operation, (5) can be rewritten to accommodate the total frequency, 4$, for both operating states:

f = 'j 1,2, (6a)

NP I "Dj =wj 1: E F(DiSmall), (6b) n=1 iER,,

Z

• j. (6c) 4.3 ALERF frequency Because the STP RCFC are independent of the concerns raised in GSI-191, and because their design can remove decay and maintain contamination RCB limits within design, concerns raised in GSI-191 would not result in containment failure. The RCFC design allows for simplification of LERF. That is, for the STP design, the change in early release frequency could be assumed directly proportional to the change in core damage frequency:

ALERF = LERFAIOR (C% R (7) 4.4 Results STP has two Cases (Case 1 and Case 2) other than the condition tested (AREVA, 2008) that are bounding for fine fiber amounts. The tested deterministic case assumed two of the three STP ECCS strainers in operation (single failure criterion). Case 1 is the most likely Saturday 1 4 th March, 2015, 07:39 14 corresponding: keeejCgstpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages case when all three strainers are in operation. In this case, far less fiber will accumulate on each strainer than for the tested case. Therefore, Case 1 is bounded by the tested case.

However, Case 2 corresponds to a case where only one train of the three STP ECCS strainers are in operation. Although this case is beyond design basis, it needs to be consid-ered in the risk analysis since at least twice as much fiber would accumulate on the single strainer than when two or more strainers are in operation. In this case, only 1/2 the tested amount of fine fiber can be assumed to be tolerated.

4.5 ACDF results When all cases are considered using (6), a slightly higher ACDF is estimated than when only one strainer is in operation. Table 4 summarizes the ACDF estimate for geometrie and arithmetic averages from Tregoning et al. (2008). The frequencies for the bounding cases are f2 = 3.32E - 6yr- 1 (Case 1) and f, = 4.34E - 8yr 1 (Case 2). As shown, the median ACDF is within Region III of the Regulatory Guide 1.174 evaluation (<< 1.OE-06).

Interpolation of Table 3 is done using the linear-linear method, (3).

Table 4: Case 1 and Case 2 results for geometric (GM) and arithmetic (AM) aggregations of Tregoning et al. (2008, Tables 7.11 and 7.19) data. Frequencies are in events/yr. Also shown are the results for a DEGB-only model for the locations that go to failure.

Continuum Break Model Quantile Case 1 GM Case 1 AM Case 2 GM Case 2 AM -I (GM) I (AM) 5th 2.64E-10 6.47E-09 3.68E-09 2.36E-08 3.08E-10 6.69E-09 50 th 7.50E-09 1.68E-07 8.30E-08 4.92E-07 8.47E-09 1.72E-07 95 th 3.43E-07 4.79E-06 1.81E-06 1.24E-05 3.62E-07 4.89E-06 Mean 1.17E-07 1.56E-06 5.1OE-07 3.93E-06 1.22E-07 1.59E-06 DEGB-Only Model 5 th 9.83E-11 8.18E-09 1.14E-09 1.66E-08 1.12E-10 8.29E-09 50 th 2.86E-09 2.07E-07 2.64E-08 3.90E-07 3.16E-09 2.09E-07 95 th 1.47E-07 7.06E-06 6.85E-07 1.21E-05 1.54E-07 7.13E-06 Mean 5.12E-08 2.06E-06 2.03E-07 3.61E-06 5.32E-08 2.08E-06 As shown in Table 4, only the 9 5 th percentile of the arithmetic mean estimate exceeded the Region III criterion in (NRC, 2011). As described in the letter to the NRC dated May 22, 2014 (ML14149A434), the geometric method of aggregation is the most appropriate estimator of LOCA frequency from (Tregoning et al., 2008).

Saturday 1 4 th March, 2015, 07:39 15 corresponding: keeejýalstpegsxom

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Table 5: ALERF evaluation for geometric and arithmetic means of the Continuum and DEG-only models.

Model ALERF using ý (GM) ALERF using 4 (AM)

Continuum break model 7.67E-09 9.99E-08 DEGB-only model 3.34E-09 1.31E-07 4.6 ALERF results Due to independence of RCB integrity from the concerns raised in GSI-191, ALERF is very small. Using (7), ALERF values were calculated based on baseline CDF and LERF values of 9.2E-06 (CDF) and 5.78E-07 (LERF). The results are summarized in Table 5.

5 RCS Thermal-hydraulics Vaghetto and Hassan (2013) studied the behavior of the RCS for scenarios where the fuel channels and the core bypass flow paths were fully blocked. They showed that, unless the LOCA was large and located on the cooling water return side (cold leg) of the RCS, then debris blockage is not a concern. Simulations were conducted using the STP RELAP5 model to analyze the reactor system response under hypothetical core blockage scenarios during selected LOCAs. The purpose of these calculations was to identify the scenarios which may produce an increase in the PCT and, subsequently, a potential core damage among selected LOCAs of different break sizes and locations under full core and core bypass blockage. The sinmlations performed are listed below:

1. SLOCA in Cold Leg

2. SLOCA in Hot Leg

3. MLOCA in Cold Leg

4. MLOCA in Hot Leg

5. DEGB in Cold Leg

6. DEGB in Hot Leg Table 6 summarizes the basic assumptions and boundary conditions for the simulations.

The simulations were designed to create a theoretically worst-case condition by blocking the core when the decay load is maximum. Both core and core bypass (baffle flow) were assumed to be instantaneously blocked after the sump switchover at the inlet. PCT was used as figure of merit to determine the success or failure of the scenario simulated. All the cases which produced a PCT less than 800'F were assumed to be successful. The cases where the maximum PCT was found to diverge after the core blockage time (exceeding Saturday 1 4 th March, 2015, 07:39 16 corresponding: keeej Cast pegs. com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages the limiting temperature of 800'F) were considered failing cases which may lead to core damage. Table 7 summarizes the results obtained.

Table 6: Summary of boundary conditions and assumptions of the STP core blockage analyses Parameter Simulation Condition ECCS 3 Trains Break location Cold leg B (bottom)

Core blockage simulation Instantaneous k-loss increase at sump switchover Reactor power (MWt) 3853 Axial power shape Double peak (0.15 and 0.8 core height)

Actinides RELAP5-3D default model Decay heat ANS73 RWST temperature 85 0F ECCS flow Nominal (realistic)

Table 7: Results of blockage scenarios showing scenarios that had PCT less than 800'F (Pass) and those that exceeded 8001F (Fail).

Break location Break Size Cold leg Hot leg Small Pass Pass Medium Fail Pass Large Fail Pass 6 Core performance metrics In addition to satisfying the strainer performance metrics, certain core performance must be acceptable with the amount of LDFG fines tested as well. There are two metrics, separately evaluated but ultimately having the same consequence, that must be found acceptable to categorize a scenario as deterministic. Decay heat removal considering LDFG blockage of the core cooling channels and freedom from boric acid precipitation must be found acceptable.

Ogden et al. (2013) have shown that the amount of fiber penetrating through the ECCS sump screen is a function of ECCS LDFG loading. In order for the screen performance metrics as tested (again AREVA, 2008, for example) to serve as the 'worst case' condition Saturday 1 4 th March, 2015, 07:39 17 corresponding: keeej Ccustpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages for deterministic characterization, the amount of fiber passing through the ECCS strainers needs to be less than that tested by the PWROG as acceptable.

6.1 Core cooling The PWROG (2011) has tested performance of the reactor core fuel assemblies under deterministically challenging conditions, and developed a performance metric in terms of the allowable amount of LDFG fiber accumulation on the reactor fuel assemblies. The currently accepted allowable amount of fiber accumulation for STP cores is 15 grams of fiber per FA. The PWROG fuel assembly testing was performed to investigate heat removal with particulate, chemical precipitates, and LDFG fiber present in the fuel assemblies but boric acid precipitation was not a consideration in the PWROG testing. As shown in the uncertainty analysis in Section 3 (Table 2), the maximum total fiber captured in the core in a CLB is calculated to be 441 gm. The STP cores use 193 FAs, resulting in a high estimate of fiber loading of less than 3 gm/FA.

As described in Section 5, HLB scenarios (as well as small break scenarios) can succeed regardless of the fiber amounts transported to the core. The analysis in Section 5 show full blockage of all flow into the core during SLOCA and HLB will not cause loss of adequate cooling.

6.2 Boric acid precipitation In addition to heat removal, the reactor core must remain below the precipitation limit for boric acid during the first few hours of the hypothesized LOCA. As a consequence of the presence of LDFG fiber transported to the fuel assemblies, boric acid buildup may be more than with the fuel assemblies clear of obstructions. Boric acid precipitation is a second core performance metric that must be evaluated as acceptable with the fraction of the tested amount of LDFG fibers passing through the ECCS strainers to the core (Section 3). The time required to reach HLSO time must be acceptable with no lower plenum mixing since it has not been determined how much fiber would allow lower plenum mixing to reduce boric acid concentration. Therefore, the deterministic STP HLSO time does not rely on lower plenum mixing.

7 Application The ROVERD method may be interesting to utility investigators who would want to screen their plant risk against the concerns raised in GSI-191. The ROVERD method could be used to design a test (or test series) having the objective to obtain a predefined risk margin.

That is, one could sequentially test starting with fiber amounts that would just meet the Regulatory Guide 1.174 Region III requirements and subsequently lesser amounts (down to that amount which just creates a fiber covering on the ECCS screen) to demonstrate Saturday 1 4 th March, 2015, 07:39 18 corresponding: keeej CUst pegs. corn

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages margin. Alternatively, perhaps preferably, one would perform simulation to design a test that would help ensure sufficiently low risk (risk in Region III of Regulatory Guide 1.174) would be realized.

Yes Requires Simulation xisting Acceptable No Determine Region II Yes etermnit teccst Acceptable Break Size (simulation/test Done Perform test OK)?

4  ;:No Inaccurate simulation (error) or peexisting test performed with too low fine fiber amount Figure 9: Process for establishing risk thresholds depending on whether an acceptable test has been previously performed or if one should be designed to achieve a specific risk goal.

Figure 9 shows a simple flow path that would accomplish this process. With an existing acceptable test, analysis would be performed to understand if it provides sufficient margin or not. If not, or absent an existing acceptable test, one would first simulate their plant to find the amount of fines transported to the sump for all possible pipe breaks. The scenarios from such a simulation could then be used to design a test (for example using CASA Grande) that would meet acceptable deterministic testing criteria. A test could be then performed and the results compared to the simulation to ensure the design is met, otherwise, a refinement to the test design could be made based on lessons learned.

Utility investigators could directly derive (Table 3), the risk margin margin desired.

As indicated in Figure 9, inaccuracies in the simulation may result in a test that doesn't provide sufficient margin. At this point, another test could be designed based on lessons learned to converge on an acceptable result. If the test demonstrates acceptable ECCS and core performance metrics for the deterministic classifications and the risk is acceptable, then low risk can be asserted for the concerns raised in GSI-191 for the particular plant.

8 Weld list In the following, tables summarize the STP scenarios in the ROVERD assessment. Table 8 summarizes the STP ROVERD risk-informed scenarios. For these scenarios, the minimum amount of fiber (the amount associated with smallest D.) at each location is listed in the Amount column.

Table 9 summarizes the STP ROVERD scenarios associated with locations that don't exceed the tested amount of fiber at the maximum possible (DEGB) break size. For these scenarios, the column 'Margin' corresponds to the additional amount of fiber required at 07:39 19 corresponding: keeejtistpegs.corn Saturday 14 Saturday th March, 1 4 th 2015, 07:39 March, 2015, 19 corresponding: keeej ý52:

st pegs. corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages the location that would be need to exceed the tested amount., The fi column also is the associated DEGB frequency.

Similar data are provided in Table 10 and Table 11 for the single train cases studied.

In this case, there are more locations that have D]-s""11 that exceed the criterion because the acceptance quantity of fiber fines is one half the tested amount (due to half the surface area available for capture).

Table 8: Data for weld locations in the risk-informed category listing the ith weld number, mass of fiber in the sump for the scenario (Ibm), location name (ID), Break size (Size), scenario frequency, f, (mean quantile, geometric aggregation), Category, and NUREG 1829 data category No. Amount (lbm) Location Size (in) fi NUREG 1829 Cat.

1 207.16 16-RC-1412-NSS-8 12.814 4.37E-07 Cat. 4 2 191.78 29-RC-1101-NSS-RSG-1A-IN-SE 13.922 2.16E-07 Cat. 4 3 191.95 29-RC-1101-NSS-5.1 13.939 2.12E-07 Cat. 4 4 192.23 29-RC-1201-NSS-5.1 14.120 1.99E-07 Cat. 5 5 192.60 29-RC-1201-RSG-1B-IN-SE 14.127 1.99E-07 Cat. 5 6 195.55 29-RC-1301-RSG-1C-IN-SE 14.342 1.97E-07 Cat. 5 7 196.62 29-RC-1301-NSS-5.1 14.405 1.96E-07 Cat. 5 8 196.03 29-RC-1401-NSS-RSC-1D-IN-SE 14.620 1.94E-07 Cat. 5 9 196.51 29-RC-1401-NSS-4.1 14.650 1.93E-07 Cat. 5 10 192.74 29-RC-1101-NSS-4 14.721 1.93E-07 Cat. 5 11 192.05 29-RC-1301-NSS-4 14.948 1.90E-07 Cat. 5 12 191.87 29-RC-1201-NSS-4 14.953 1.90E-07 Cat. 5 13 194.24 29-RC-1401-NSS-3 15.172 1.88E-07 Cat. 5 14 193.97 31-RC-1102-NSS-2 16.525 1.75E-07 Cat. 5 15 194.36 31-RC-1202-NSS-RSG-1B-ON-SE 16.724 1.73E-07 Cat. 5 16 i95.82 31-RC-1102-NSS-RSG-1A-ON-SE 16.760 1.72E-07 Cat. 5 17 201.09 31-RC-1202-NSS-2 16.819 1.72E-07 Cat. 5 18 191.78 31-RC-1202-NSS-3 17.020 1.70E-07 Cat. 5 19 192.64 31-RC-1302-NSS-2 17.209 1.68E-07 Cat. 5 20 201.67 31-RC-1202-NSS-1.1 17.279 1.67E-07 Cat. 5 21 194.24 31-RC-1102-NSS-3 17.338 1.66E-07 Cat. 5 22 192.56 31-RC-1302-NSS-1.1 17.593 1.64E-07 Cat. 5 23 193.22 31-RC-1302-NSS-RSG-1C-ON-SE 17.659 1.63E-07 Cat. 5 24 192.46 31-RC-1202-NSS-4 17.665 1.63E-07 Cat. 5 25 193.39 31-RC-1302-NSS-3 17.674 1.63E-07 Cat. 5 26 211.20 31-RC-1102-NSS-1.1 17.793 1.62E-07 Cat. 5 27 193.53 31-RC-1402-NSS-RSG-ID-ON-SE 17.876 1.61E-07 Cat. 5 28 196.61 31-RC-1102-NSS-4 18.126 1.58E-07 Cat. 5 29 197.10 31-RC-1402-NSS-1.1 18.140 1.58E-07 Cat. 5 30 191.86 31-RC-1402-NSS-2 18.233 1.57E-07 Cat. 5 31 192.24 31-RC-1302-NSS-4 18.367 1.56E-07 Cat. 5 32 192.93 31-R.C-1402-NSS-3 19.246 1.47E-07 Cat. 5 33 192.77 31-RC-1202-NSS-8 19.297 1.47E-07 Cat. 5 34 191.93 27.5-RC-1103-NSS-1 19.454 1.45E-07 Cat. 5 35 192.02 31-RC-1102-NSS-8 19.547 1.44E-07 Cat. 5 36 192.16 27.5-RC-1203-NSS-1 19.584 1.44E-07 Cat. 5 continued next page ...

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NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

.... continued No. Amount (Ibm) Location Size (in) fi NUREG 1829 Cat.

37 192.23 31-RC-1402-NSS-4 20.225 1.37E-07 Cat. 5 38 192.27 31-RC-1302-NSS-8 20.367 1.36E-07 Cat. 5 39 191.80 27.5-RC-1303-NSS-1 21.007 1.30E-07 Cat. 5 40 192.07 31-RC-1202-NSS-9 21.114 1.28E-07 Cat. 5 41 192.04 31-RC-1102-NSS-9 21.255 1.27E-07 Cat. 5 42 192.16 27.5-RC-1403-NSS-1 22.068 1.19E-07 Cat. 5 43 191.94 31-RC-1402-NSS-8 22.155 1.18E-07 Cat. 5 44 191.79 31-RC-1302-NSS-9 23.040 1.09E-07 Cat. 5 45 191.96 31-RC-1402-NSS-9 25.303 8.63E-08 Cat. 5 Table 9: DEGB data (largest break size) for weld locations in the deterministic category showing listing the *th weld number, the margin to the mass of fiber in the sump produced to the tested amount (Ibm),

location name, Break size (Size), scenario DEGB frequency, fi (mean quantile, geometric aggregation), and NUREG 1829 data category No. Margin (lbm) Location DEGB f2 NUREG 1829 Cat.

Size (in) 46 163.2 0.75-CV-1122-BB1-1 0.614 1.75E-03 Cat. 1 47 163.2 0.75-CV-1122-BB1-2 0.614 1.75E-03 Cat. 1 48 163.3 0.75-CV-1124-BBl-1 0.614 1.75E-03 Cat. 1 49 163.3 0.75-CV-1124-BB1-2 0.614 1.75E-03 Cat. 1 50 163.3 0.75-CV-1126-BBl-1 0.614 1.75E-03 Cat. 1 51 163.1 0.75-CV-1126-BB1-2 0.614 1.75E-03 Cat. 1 52 163.3 0.75-CV-1128-BB1-I 0.614 1.75E-03 Cat. 1 53 163.3 0.75-CV-1128-BB1-2 0.614 1.75E-03 Cat. 1 54 163.1 0.75-RC-1001-BBI-1 0.614 1.75E-03 Cat. 1 55 163.0 0.75-RC-1002-BB2-1 0.614 1.75E-03 Cat. 1 56 163.0 0.75-RC-1112-BBI-1 0.614 1.75E-03 Cat. 1 57 162.9 0.75-RC-1114-BBI-1 0.614 1.75E-03 Cat. 1 58 163.0 0.75-RC-1125-BB1-1 0.614 1.75E-03 Cat. 1 59 162.9 0.75-RC-1125-BB1-2 0.614 1.75E-03 Cat. 1 60 163.0 0.75-RC-1126-BBl-1 0.614 1.75E-03 Cat. 1 61 163.0 0.75-RC-1212-BBl-1 0.614 1.75E-03 Cat. 1 62 162.9 0.75-RC-1214-BB1-1 0.614 1.75E-03 Cat. 1 63 163.0 0.75-RC-1221-BBl-1 0.614 1.75E-03 Cat. 1 64 163.0 0.75-RC-1221-BB1-2 0.614 1.75E-03 Cat. 1 65 163.0 0.75-RC-1312-BBl-1 0.614 1.75E-03 Cat. 1 66 162.9 0.75-RC-1324-BBl-1 0.614 1.75E-03 Cat. 1 67 163.0 0.75-RC-1423-BB1-1 0.614 1.75E-03 Cat. 1 68 163.1 0.75-SI-1130-BB2-1 0.614 1.75E-03 Cat. 1 69 163.1 0.75-SI-1132-BBl-1 0.614 1.75E-03 Cat. 1 70 163.1 0.75-SI-1218-BB1-1 0.614 1.75E-03 Cat. 1 71 163.1 0.75-SI-1223-BB2-1 0.614 1.75E-03 Cat. 1 72 162.9 0.75-SI-1315-BB1-1 0.614 1.75E-03 Cat. 1 73 163.2 0.75-SI-1323-BB1-1 0.614 1.75E-03 Cat. 1 74 163.1 0.75-SI-1327-BB1-1 0.614 1.75E-03 Cat. 1 continued next page ...

Saturday 14 th March, 2015, 07:39 21 corresponding: keeejCdstpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 75 163.1 0.75-SI-1327-BB1-2 0.614 1.75E-03 Cat. 1 76 163.1 0.75-SI- 1327-BB1-3 0.614 1.75E-03 Cat. I 77 163.1 0.75-SI-1328-BB2-1 0.614 1.75E-03 Cat. 1 78 162.7 1-RC-1003-BBI-1 0.815 1.49E-03 Cat. 1 79 163.0 1-RC-1123-BB1-1 0.815 1.49E-03 Cat. 1 80 162.9 1-RC-1422-BBl-1 0.815 1.49E-03 Cat. 1 81 161.6 1.5-RC-1412-NSS-1 1.338 7.98E-04 Cat. 1 82 163.2 2(1.5)-CV-1122-BB1-1 1.338 7.98E-04 Cat. 1 83 163.0 2(1.5)-CV-1122-BB1-2 1.338 7.98E-04 Cat. 1 84 163.2 2(1.5)-CV-1124-BBl-1 1.338 7.98E-04 Cat. 1 85 162.9 2(1.5)-CV-1124-BB1-2 1.338 7.98E-04 Cat. I 86 162.7 2(1.5)-CV-1126-BBl-1 1.338 7.98E-04 Cat. 1 87 162.8 2(1.5)-CV-1126-BB1-2 1.338 7.98E-04 Cat. 1 88 163.0 2(1.5)-CV-1128-BB1-1 1.338 7.98E-04 Cat. 1 89 162.8 2(1.5)-CV-1128-BB1-2 1.338 7.98E-04 Cat. 1 90 163.0 2-CV-1121-BBE-1 1.689 4.01E-04 Cat. 2 91 162.8 2-CV-1121-BB1-2 1.689 4.01E-04 Cat. 2 92 162.7 2-CV-1121-BB1-3 1.689 4.01E-04 Cat. 2 93 162.5 2-CV-1122-BBl-1 1.689 4.01E-04 Cat. 2 94 162.6 2-CV-1122-BB1-2 1.689 4.01E-04 Cat. 2 95 162.6 2-CV-1122-BB1-3 1.689 4.01E-04 Cat. 2 96 162.6 2-CV-1122-BB1-4 1.689 4.01E-04 Cat. 2 97 162.6 2-CV-1122-BB1-5 1.689 4.01E-04 Cat. 2 98 162.8 2-CV-1122-BB1-6 1.689 4.01E-04 Cat. 2 99 162.6 2-CV-1124-BBl-1 1.689 4.01E-04 Cat. 2 100 162.5 2-CV-1124-BBl-10 1.689 4.01E-04 Cat. 2 101 162.5 2-CV-1124-BBl-ll 1.689 4.01E-04 Cat. 2 102 163.0 2-CV-1124-BB1-12 1.689 4.01E-04 Cat. 2 103 162.9 2-CV-1124-BB1-13 1.689 4.01E-04 Cat. 2 104 162.6 2-CV-1124-BB1-2 1.689 4.01E-04 Cat. 2 105 162.6 2-CV-1124-BB1-3 1.689 4.01E-04 Cat. 2 106 162.5 2-CV-1124-BB1-4 1.689 4.01E-04 Cat. 2 107 162.5 2-CV-1124-BB1-5 1.689 4.01E-04 Cat. 2 108 162.5 2-CV-1124-BB1-6 1.689 4.01E-04 Cat. 2 109 162.7 2-CV-1124-BB1-7 1.689 4.01E-04 Cat. 2 110 162.6 2-CV-1124-BB1-8 1.689 4.01E-04 Cat. 2 111 162.5 2-CV-1124-BB1-9 1.689 4.01E-04 Cat. 2 112 163.1 2-CV-1126-BBl-1 1.689 4.01E-04 Cat. 2 113 162.4 2-CV-1126-BBl-10 1.689 4.01E-04 Cat. 2 114 162.5 2-CV-1126-BB1-11 1.689 4.01E-04 Cat. 2 115 163.1 2-CV-1126-BB1-2 1.689 4.01E-04 Cat. 2 116 163.0 2-CV-1126-BB1-3 1.689 4.01E-04 Cat. 2 117 162.9 2-CV-1126-BB1-4 1.689 4.01E-04 Cat. 2 118 162.9 2-CV-1126-BBE-5 1.689 4.01E-04 Cat. 2 119 162.9 2-CV-1126-BB1-6 1.689 4.01E-04 Cat. 2 120 162.8 2-CV-1126-BB1-7 1.689 4.01E-04 Cat. 2 continued next page ...

22 corresponding: keeej~stpegs.com Ih March, Saturday 1144 th Saturday 2015, 07:39 March, 2015, 07:39 22 corresponding: keeej(9stpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 121 161.9 2-CV-1126-BB1-8 1.689 4.01E-04 Cat. 2 122 161.8 2-CV-1126-BB1-9 1.689 4.01E-04 Cat. 2 123 163.3 2-CV-1128-BB1-1 1.689 4.01E-04 Cat. 2 124 163.1 2-CV-1 128-BB1-2 1.689 4.01E-04 Cat. 2 125 163.0 2-CV-1128-BB1-3 1.689 4.01E-04 Cat. 2 126 163.0 2-CV-1128-BB1-3A 1.689 4.01E-04 Cat. 2 127 162.9 2-CV-1128-BB1-3B 1.689 4.01E-04 Cat. 2 128 162.9 2-CV-1128-BB1-4 1.689 4.01E-04 Cat. 2 129 162.9 2-CV-1128-BB1-5 1.689 4.01E-04 Cat. 2 130 162.9 2-CV-1128-BB1-6 1.689 4.01E-04 Cat. 2 131 162.8 2-CV-1128-BB1-7 1.689 4.01E-04 Cat. 2 132 162.8 2-CV-1141-BB1-1 1.689 4.01E-04 Cat. 2 133 162.9 2-CV-1141-BB1-2 1.689 4.01E-04 Cat. 2 134 162.7 2-RC-1003-BBI-1 1.689 4.01E-04 Cat. 2 135 162.4 2-RC-1003-BB1-2 1.689 4.01E-04 Cat. 2 136 162.0 2-RC-1120-BBL-1 1.689 4.01E-04 Cat. 2 137 162.2 2-RC-1120-BB1-2 1.689 4.01E-04 Cat. 2 138 161.6 2-RC-1121-BBR-1 1.689 4.01E-04 Cat. 2 139 162.7 2-RC-1121-BB1-2 1.689 4.01E-04 Cat. 2 140 162.7 2-RC-1121-BB1-3 1.689 4.01E-04 Cat. 2 141 162.7 2-RC-1121-BB1-3A 1.689 4.01E-04 Cat. 2 142 162.8 2-RC-1121-BB1-3B 1.689 4.01E-04 Cat. 2 143 162.9 2-RC-1121-BB1-4 1.689 4.01E-04 Cat. 2 144 161.9 2-RC-1219-BBI-1 1.689 4.01E-04 Cat. 2 145 162.1 2-RC-1219-BB1-2 1.689 4.01E-04 Cat. 2 146 161.6 2-RC-1220-BBl-1 1.689 4.01E-04 Cat. 2 147 162.8 2-RC-1220-BB1-2 1.689 4.01E-04 Cat. 2 148 162.8 2-RC-1220-BB1-3 1.689 4.01E-04 Cat. 2 149 162.9 2-RC-1220-BB1-4 1.689 4.01E-04 Cat. 2 150 161.8 2-RC-1319-BBl-1 1.689 4.01E-04 Cat. 2 151 162.2 2-RC-1319-BB1-2 1.689 4.01E-04 Cat. 2 152 162.2 2-RC-1321-BBR-1 1.689 4.01E-04 Cat. 2 153 162.4 2-RC-1321-BB1-4 1.689 4.01E-04 Cat. 2 154 162.4 2-RC-1321-BB1-5 1.689 4.01E-04 Cat. 2 155 162.5 2-RC-1321-BB1-6 1.689 4.01E-04 Cat. 2 156 162.0 2-RC-1417-BBl-1 1.689 4.01E-04 Cat. 2 157 162.1 2-RC-1417-BB1-2 1.689 4.01E-04 Cat. 2 158 161.6 2-RC-1418-BBI-1 1.689 4.01E-04 Cat. 2 159 162.2 2-RC-1418-BB1-2 1.689 4.01E-04 Cat. 2 160 162.2 2-RC-1418-BB1-3 1.689 4.01E-04 Cat. 2 161 162.3 2-RC-1418-BB1-4 1.689 4.01E-04 Cat. 2 162 162.4 2-RC-1418-BB1-5 1.689 4.01E-04 Cat. 2 163 162.6 2-RC-1418-BB1-6 1.689 4.01E-04 Cat. 2 164 162.3 2-RC-1419-BBI-1 1.689 4.01E-04 Cat. 2 165 162.5 2-RC-1419-BB1-2 1.689 4.01E-04 Cat. 2 166 162.5 2-RC-1419-BB1-3 1.689 4.01E-04 Cat. 2 continued next page ...

23 corresponding: keeej©stpegs.corn Saturday 14 Ih March, 1 4 th 2015, 07:39 March, 2015, 07:39 23 corresponding: keeej@stpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 167 162.8 2-RC-1419-BBI-4 1.689 4.01E-04 Cat. 2 168 161.8 31-RC-1102-NSS-5 1.689 4.01E-04 Cat. 2 169 161.5 31-RC-1102-NSS-6 1.689 4.01E-04 Cat. 2 170 161.8 31-RC-1202-NSS-5 1.689 4.01E-04 Cat. 2 171 161.4 31-RC-1202-NSS-7 1.689 4.01E-04 Cat. 2 172 161.7 31-RC-1302-NSS-5 1.689 4.01E-04 Cat. 2 173 161.8 31-RC-1402-NSS-5 1.689 4.01E-04 Cat. 2 174 161.4 31-RC-1402-NSS-7 1.689 4.01E-04 Cat. 2 175 161.3 2.5-RC-1003-BBI-I 2.125 2.73E-04 Cat. 2 176 161.5 2.5-RC-1003-BBI-2 2.125 2.73E-04 Cat. 2 177 161.6 2.5-RC-1003-BBI-3 2.125 2.73E-04 Cat. 2 178 161.6 2.5-RC-1003-BBI-4 2.125 2.73E-04 Cat. 2 179 161.6 2.5-RC-1003-BB1-5 2.125 2.73E-04 Cat. 2 180 161.6 2.5-RC-1003-BBI-6 2.125 2.73E-04 Cat. 2 181 158.9 31-RC-1 102-NSS-7 2.626 1.26E-04 Cat. 2 182 158.9 31-RC-1202-NSS-6 2.626 1.26E-04 Cat. 2 183 158.9 31-RC-1302-NSS-6 2.626 1.26E-04 Cat. 2 184 158.9 31-RC-1402-NSS-6 2.626 1.26E-04 Cat. 2 185 161.1 3-RC-1003-BBI-I 2.626 1.26E-04 Cat. 2 186 161.2 3-RC-1003-BBI-2 2.626 1.26E-04 Cat. 2 187 161.2 3-RC-1015-NSS-1 2.626 1.26E-04 Cat. 2 188 160.6 3-RC-1015-NSS-10 2.626 1.26E-04 Cat. 2 189 160.7 3-RC-1015-NSS-11 2.626 1.26E-04 Cat. 2 190 161.2 3-RC-1015-NSS-12 2.626 1.26E-04 Cat. 2 191 161.9 3-RC-1015-NSS-13 2.626 1.26E-04 Cat. 2 192 163.0 3-RC-1015-NSS-14 2.626 1.26E-04 Cat. 2 193 163.1 3-RC-1015-NSS-15 2.626 1.26E-04 Cat. 2 194 162.1 3-RC-1015-NSS-16 2.626 1.26E-04 Cat. 2 195 161.4 3-RC-1015-NSS-2 2.626 1.26E-04 Cat. 2 196 161.6 3-RC-1015-NSS-3 2.626 1.26E-04 Cat. 2 197 162.2 3-RC-1015-NSS-4 2.626 1.26E-04 Cat. 2 198 162.7 3-RC-1015-NSS-5 2.626 1.26E-04 Cat. 2 199 163.2 3-RC-1015-NSS-6 2.626 1.26E-04 Cat. 2 200 163.3 3-RC-1015-NSS-7 2.626 1.26E-04 Cat. 2 201 163.3 3-RC-1015-NSS-8 2.626 1.26E-04 Cat. 2 202 160.6 3-RC-1015-NSS-9 2.626 1.26E-04 Cat. 2 203 159.6 3-RC-1106-BBI-25 2.626 1.26E-04 Cat. 2 204 159.6 3-RC-1206-BBI-28 2.626 1.26E-04 Cat. 2 205 159.6 3-RC-1306-BBI-28 2.626 1.26E-04 Cat. 2 206 159.7 3-RC-1406-BB1-25 2.626 1.26E-04 Cat. 2 207 153.8 27.5-RC-1 103-NSS-3 3.438 1.44E-05 Cat. 3 208 155.6 27.5-RC-1 103-NSS-5 3.438 1.44E-05 Cat. 3 209 156.2 27.5-RC-1303-NSS-4 3.438 1.44E-05 Cat. 3 210 155.2 27.5-RC-1403-NSS-3 3.438 1.44E-05 Cat. 3 211 155.4 27.5-RC-1403-NSS-4 3.438 1.44E-05 Cat. 3 212 155.2 31-RC-1302-NSS-7 3.438 1.44E-05 Cat. 3 continued next page ...

Saturday 1 4 th March, 2015, 07:39 24 corresponding: keeejCastpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 213 161.8 4-CV-1001-BBI-1 3.438 1.44E-05 Cat. 3 214 162.3 4-CV-1001-BB1-2 3.438 1.44E-05 Cat. 3 215 162.3 4-CV-1118-BBI-1 3.438 1.44E-05 Cat. 3 216 161.5 4-CV-1118-BB1-2 3.438 1.44E-05 Cat. 3 217 160.3 4-CV-1120-BBI-1 3.438 1.44E-05 Cat. 3 218 159.9 4-CV-1120-BB1-2 3.438 1.44E-05 Cat. 3 219 159.0 4-RC-1000-BBI-1 3.438 1.44E-05 Cat. 3 220 159.7 4-RC-1000-BB1-2 3.438 1.44E-05 Cat. 3 221 159.7 4-RC- 1000-BB 1-3 3.438 1.44E-05 Cat. 3 222 160.1 4-RC-1000-BB1-4 3.438 1.44E-05 Cat. 3 223 160.1 4-RC-1000-BB1-5 3.438 1.44E-05 Cat. 3 224 159.9 4-RC-1000-BB1-6 3.438 1.44E-05 Cat. 3 225 159.8 4-RC-1000-BB1-7 3.438 1.44E-05 Cat. 3 226 158.6 4-RC-1000-BB1-8 3.438 1.44E-05 Cat. 3 227 159.1 4-RC-1003-BB1-1 3.438 1.44E-05 Cat. 3 228 159.2 4-RC-1003-BBI-2 3.438 1.44E-05 Cat. 3 229 159.1 4-RC-1003-BB1-3 3.438 1.44E-05 Cat. 3 230 158.6 4-RC-1003-BB1-4 3.438 1.44E-05 Cat. 3 231 154.3 4-RC-1123-BB1-1 3.438 1.44E-05 Cat. 3 232 160.6 4-RC-1123-BBl-10 3.438 1.44E-05 Cat. 3 233 161.4 4-RC-1123-BBl-11 3.438 1.44E-05 Cat. 3 234 161.8 4-RC-1123-BB1-12 3.438 1.44E-05 Cat. 3 235 161.8 4-RC-1123-BB1-13 3.438 1.44E-05 Cat. 3 236 162.0 4-RC-1123-BB1-14 3.438 1.44E-05 Cat. 3 237 161.8 4-RC-1123-BBl-15 3.438 1.44E-05 Cat. 3 238 159.8 4-RC-1123-BB1-16 3.438 1.44E-05 Cat. 3 239 159.1 4-RC-1123-BBl-17 3.438 1.44E-05 Cat. 3 240 157.7 4-RC-1123-BBl-18 3.438 1.44E-05 Cat. 3 241 157.7 4-RC-1123-BB1-19 3.438 1.44E-05 Cat. 3 242 161.8 4-RC-1123-BB1-2 3.438 1.44E-05 Cat. 3 243 158.7 4-RC-1123-BB1-20 3.438 1.44E-05 Cat. 3 244 161.8 4-R.C-1123-BB1-3 3.438 1.44E-05 Cat. 3 245 161.8 4-RC-1123-BB1-4 3.438 1.44E-05 Cat. 3 246 161.9 4-RC-1123-BB175 3.438 1.44E-05 Cat. 3 247 161.9 4-RC-1 123-BB1-6 3.438 1.44E-05 Cat. 3 248 161.8 4-RC-1123-BB1-7 3.438 1.44E-05 Cat. 3 249 161.8 4-RC-1123-BB1-8 3.438 1.44E-05 Cat. 3 250 160.1 4-RC-1123-BB1-9 3.438 1.44E-05 Cat. 3 251 161.2 4-RC-1126-BB1-1 3.438 1.44E-05 Cat. 3 252 160.2 4-RC-1126-BBI-2 3.438 1.44E-05 Cat. 3 253 159.9 4-RC-1126-BB1-3 3.438 1.44E-05 Cat. 3 254 160.0 4-RC-1126-BB1-4 3.438 1.44E-05 Cat. 3 255 159.3 4-RC-1126-BB1-5 3.438 1.44E-05 Cat. 3 256 156.0 4-RC-1126-BB1-6 3.438 1.44E-05 Cat. 3 257 155.4 4-RC-1320-BBl-1 3.438 1.44E-05 -Cat. 3 258 161.4 4-RC-1320-BB1-10 3.438 1.44E-05 Cat. 3 continued next page ...

25 corresponding: keeej@stpegs.com Saturday 14 Saturday th March, 1 4 Ih 2015, 07:39 March, 2015, 07:39 25 corresponding: keeej acstpegs-com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB f, NUREG 1829 Cat.

Size (in) 259 161.5 4-RC-1320-BBl-11 3.438 1.44E-05 Cat. 3 260 161.5 4-RC-1320-BBl-12 3.438 1.44E-05 Cat. 3 261 156.0 4-RC-1320-BB1-2 3.438 1.44E-05 Cat. 3 262 156.6 4-RC-1320-BB1-3 3.438 1.44E-05 Cat. 3 263 158.8 4-RC-1320-BB1-4 3.438 1.44E-05 Cat. 3 264 159.2 4-RC-1320-BB1-5 3.438 1.44E-05 Cat. 3 265 159.6 4-RC-1320-BB1-6 3.438 1.44E-05 Cat. 3 266 159.9 4-RC-1320-BB1-7 3.438 1.44E-05 Cat. 3 267 160.2 4-R.C-1320-BB1-8 3.438 1.44E-05 Cat. 3 268 161.1 4-RC-1320-BB1-9 3.438 1.44E-05 Cat. 3 269 160.8 4-RC-1323-BBI-1 3.438 1.44E-05 Cat. 3 270 161.0 4-RC-1323-BB1-2 3.438 1.44E-05 Cat. 3 271 161.5 4-RC-1323-BB1-3 3.438 1.44E-05 Cat. 3 272 156.6 4-RC-1323-BB1-4 3.438 1.44E-05 Cat. 3 273 156.1 4-RC-1420-BB1-1 3.438 1.44E-05 Cat. 3 274 155.8 4-RC-1422-BBl-1 3.438 1.44E-05 Cat. 3 275 161.8 4-RC-1422-BBl-10 3.438 1.44E-05 Cat. 3 276 161.8 4-RC-1422-BB1-11 3.438 1.44E-05 Cat. 3 277 159.8 4-RC-1422-BB1-12 3.438 1.44E-05 Cat. 3 278 160.6 4-RC-1422-BB1-13 3.438 1.44E-05 Cat. 3 279 160.8 4-RC-1422-BBl-14 :3.438 1.44E-05 Cat. 3 280 161.2 4-RC-1422-BB1-15 3.438 1.44E-05 Cat. 3 281 161.7 4-RC-1422-BBl-16 3.438 1.44E-05 Cat. 3 282 162.0 4-RC-1422-BB1-17 3.438 1.44E-05 Cat. 3 283 161.8 4-RC-1422-BB1-18 3.438 1.44E-05 Cat. 3 284 162.0 4-RC-1422-BBl-19 3.438 1.44E-05 Cat. 3 285 156.7 4-RC-1422-BB1-2 3.438 1.44E-05 Cat. 3 286 162.1 4-RC-1422-BB1-20 3.438 1.44E-05 Cat. 3 287 160.3 4-RC-1422-BB1-21 3.438 1.44E-05 Cat. 3 288 159.8 4-RC-1422-BB 1-22 3.438 1.44E-05 Cat. 3 289 159.6 4-RC-1422-BB1-23 3.438 1.44E-05 Cat. 3 290 157.4 4-RC-1422-BB1-3 3.438 1.44E-05 Cat. 3 291 156.8 4-RC-1422-BBI-4 3.438 1.44E-05 Cat. 3 292 157.4 4-RC-1422-BB1-5 3.438 1.44E-05 Cat. 3 293 161.6 4-RC-1422-BB1-6 3.438 1.44E-05 Cat. 3 294 161.6 4-RC-1422-BB1-7 3.438 1.44E-05 Cat. 3 295 161.6 4-RC-1422-BB1-8 3.438 1.44E-05 Cat. 3 296 161.6 4-RC-1422-BBI-9 3.438 1.44E-05 Cat. 3 297 148.9 6-RC-1003-BB1-1 5.189 8.12E-06 Cat. 3 298 150.4 6-RC-1003-BB1-10 5.189 8. 12E-06 Cat. 3 299 150.2 6-RC-1003-BBI-11 5.189 8.12E-06 Cat. 3 300 147.6 6-RC-1003-BB1-11A 5.189 8.12E-06 Cat. 3 301 145.9 6-R.C-1003-BB1-11B 5.189 8.12E-06 Cat. 3 302 142.6 6-R.C-1003-BB1-12 5.189 8.12E-06 Cat. 3 303 138.7 6-RC-1003-BB1-13 5.189 8.12E-06 Cat. 3 304 133.7 6-RC-1003-BBI-13A 5.189 8.12E-06 Cat. 3 continued next page ...

26 corresponding: keeej~stpegs.com Saturday 14 March, 2015, th March, 1 4 Ih 07:39 201S, 07:39 26 corresponding: k-eeejK(jstpegs.coni

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 305 129.6 6-RC-1003-BBl-14 5.189 8.12E-06 Cat. 3 306 148.9 6-RC-1003-BB1-2 5.189 8.12E-06 Cat. 3 307 148.9 6-RC-1003-BBI-3 5.189 8.12E-06 Cat. 3 308 149.1 6-RC-1003-BB1-4 5.189 8.12E-06 Cat. 3 309 149.4 6-RC-1003-BB1-5 5.189 8.12E-06 Cat. 3 310 150.0 6-RC-1003-BB1-6 5.189 8.12E-06 Cat. 3 311 148.3 6-RC-1003-BBI-7 5.189 8.12E-06 Cat. 3 312 144.4 6-RC-1003-BB1-8 5.189 8.12E-06 Cat. 3 313 143.9 6-RC-1003-BB1-9 5.189 8.12E-06 Cat. 3 314 143.9 6-RC-1003-BB1-9A 5.189 8.12E-06 Cat. 3 315 143.9 6-RC-1003-BB1-9B 5.189 8.12E-06 Cat. 3 316 129.7 6-RC-1003-BB1-PRZ-1-N2-SE 5.189 8.12E-06 Cat. 3 317 136.5 6-RC-1004-NSS-1 5.189 8.12E-06 Cat. 3 318 138.5 6-RC- 1004-NSS-2 5.189 8.12E-06 Cat. 3 319 142.1 6-RC- 1004-NSS-3 5.189 8.12E-06 Cat. 3 320 137.3 6-RC-1004-NSS-4 5.189 8.12E-06 Cat. 3 321 136.1 6-RC-1004-NSS-5 5.189 8.12E-06 Cat. 3 322 142.9 6-RC-1004-NSS-6 5.189 8. 1 2E-06 Cat. 3 323 145.3 6-RC-1004-NSS-7 5.189 8.12E-06 Cat. 3 324 136.5 6-RC-1004-NSS-PRZ- 1-N3-SE 5.189 8.12E-06 Cat. 3 325 134.4 6-RC- 1009-NSS- 1 5.189 8.12E-06 Cat. 3 326 136.1 6-RC-1009-NSS-2 5.189 8.12E-06 Cat. 3 327 140.7 6-RC-1009-NSS-3 5.189 8.12E-06 Cat. 3 328 136.8 6-RC-1009-NSS-4 5.189 8.12E-06 Cat. 3 329 133.7 6-RC-1009-NSS-5 5.189 8.12E-06 Cat. 3 330 132.6 6-RC- 1009-NSS-6 5.189 8.12E-06 Cat. 3 331 134.1 6-RC-1009-NSS-7 5.189 8.12E-06 Cat. 3 332 137.3 6-RC-1009-NSS-8 5.189 8.12E-06 Cat. 3 333 140.0 6-RC-1009-NSS-9 5.189 8.12E-06 Cat. 3 334 134.6 6-RC-1009-NSS-PRZ-1-N4C-SE 5.189 8.12E-06 Cat. 3 335 131.5 6-RC-1012-NSS-1 5.189 8.12E-06 Cat. 3 336 139.0 6-RC-1012-NSS-10 5.189 8.12E-06 Cat. 3 337 139.6 6-RC-1012-NSS-11 5.189 8.12E-06 Cat. 3 338 133.0 6-RC-1012-NSS-2 5.189 8.12E-06 Cat. 3 339 134.0 6-RC-1012-NSS-3 5.189 8.12E-06 Cat. 3 340 134.3 6-RC-1012-NSS-4 5.189 8.12E-06 Cat. 3 341 136.9 6-RC-1012-NSS-5 5.189 8.12E-06 Cat. 3 342 137.7 6-RC-1012-NSS-6 5.189 8.12E-06 Cat. 3 343 139.0 6-RC-1012-NSS-7 5.189 8.12E-06 Cat. 3 344 138.5 6-RC-1012-NSS-8 5.189 8.12E-06 Cat. 3 345 135.8 6-RC-1012-NSS-9 5.189 8.12E-06 Cat. 3 346 131.4 6-RC-1012-NSS-PRZ-1-N4B-SE 5.189 8.12E-06 Cat. 3 347 132.1 6-RC-1015-NSS-1 5.189 8.12E-06 Cat. 3 348 139.7 6-RC-1015-NSS-10 5.189 8.12E-06 Cat. 3 349 150.6 6-RC-1015-NSS-11 5.189 8.12E-06 Cat. 3 350 152.5 6-RC-1015-NSS-12 5.189 8.12E-06 Cat. 3 continued next page ...

Saturday 1 4 th March, 2015, 07:39 27 corresponding: keeeingstpegs.coni

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 351 152.8 6-RC-1015-NSS-13 5.189 8.12E-06 Cat. 3 352 151.9 6-RC-1015-NSS-14 5.189 8.12E-06 Cat. 3 353 151.8 6-RC-1015-NSS-15 5.189 8.12E-06 Cat. 3 354 134.0 6-RC-1015-NSS-2 5.189 8.12E-06 Cat. 3 355 135.3 6-RC-1015-NSS-3 5.189 8.12E-06 Cat. 3 356 134.2 6-RC-1015-NSS-4 5.189 8.12E-06 Cat. 3 357 132.0 6-RC-1015-NSS-5 5.189 8.12E-06 Cat. 3 358 131.3 6-RC-1015-NSS-6 5.189 8.12E-06 Cat. 3 359 131.2 6-RC-1015-NSS-7 5.189 8.12E-06 Cat. 3 360 134.1 6-RC-1015-NSS-8 5.189 8.12F-06 Cat. 3 361 136.5 6-RC-1015-NSS-9 5.189 8.12E-06 Cat. 3 362 162.7 6-SI-1108-BBI-1 5.189 8.12E-06 Cat. 3 363 162.6 6-SI-1108-BB1-2 5.189 8.12E-06 Cat. 3 364 162.0 6-SI-1108-BB1-3 5.189 8.12E-06 Cat. 3 365 154.6 6-SI-1108-BB1-4 5.189 8.12E-06 Cat. 3 366 159.9 6-SI-1111-BBI-1 5.189 8.12E-06 Cat. 3 367 159.8 6-SI-1111-BB1-2 5.189 8.12E-06 Cat. 3 368 162.7 6-SI-1208-BB1-1 5.189 8.12E-06 Cat. 3 369 162.7 6-SI-1208-BB1-2 5.189 8.12E-06 Cat. 3 370 162.0 6-SI-1208-BB1-3 5.189 8.12E-06 Cat. 3 371 155.6 6-SI-1208-BB1-4 5.189 8.12E-06 Cat. 3 372 160.6 6-SI-1211-BBI-I 5.189 8.12E-06 Cat. 3 373 160.4 6-SI-1211-BB1-2 5.189 8.12E-06 Cat. 3 374 159.7 6-S1-1308-BB1-1 5.189 8.12E-06 Cat. 3 375 160.9 6-SI-1308-BB1-2 5.189 8.12E-06 Cat. 3 376 161.2 6-SI-1308-BB1-3 5.189 8.12E-06 Cat. 3 377 160.1 6-SI-1308-BB1-4 5.189 8.12E-06 Cat. 3 378 149.0 6-SI-1327-BB1-1 5.189 8.12E-06 Cat. 3 379 149.5 6-SI-1327-BB1-2 5.189 8.12E-06 Cat. 3 380 150.0 6-SI-1327-BB1-3 5.189 8.12E-06 Cat. 3 381 149.5 6-SI-1327-BB1-4 5.189 8.12E-06 Cat. 3 382 150.4 6-SI-1327-BB1-5 5.189 8.12E-06 Cat. 3 383 151.2 6-SI-1327-BB1-6 5.189 8.12E-06 Cat. 3 384 152.2 6-SI-1327-BB1-7 5.189 8.12E-06 Cat. 3 385 131.8 29-RC-1101-NSS-2 6.813 2.27E-06 Cat. 3 386 131.9 29-RC-1201-NSS-2 6.813 2.27E-06 Cat. 3 387 131.4 29-RC-1301-NSS-2 6.813 2.27E-06 Cat. 3 388 142.1 8-RC-1114-BBI-1 6.813 2.27E-06 Cat. 3 389 143.6 8-RFC-1114-BB1-2 6.813 2.27E-06 Cat. 3 390 142.1 8-RC-1114-BB1-3 6.813 2.27E-06 Cat. 3 391 139.2 8-RC- 1114-BB 1-4 6.813 2.27E-06 Cat. 3 392 135.5 8-RC-1114-BB1-5 6.813 2.27E-06 Cat. 3 393 132.2 8-RC-1114-BB1-6 6.813 2.27E-06 Cat. 3 394 142.4 8-RC-1214-BBI-1 6.813 2.27E-06 Cat. 3 395 143.9 8-RC-1214-BB1-2 6.813 2.27E-06 Cat. 3 396 142.6 8-RC-1214-BB1-3 6.813 2.27E-06 Cat. 3 continued next page ...

Saturday 1 4 th March, 2015, 07:39 28 corresponding: keeej 0-st pegs. coin

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 397 139.6 8-R.C-1214-BB1-4 6.813 2.27E-06 Cat. 3 398 136.0 8-RC-1214-BB1-5 6.813 2.27E-06 Cat. 3 399 132.9 8-RC-1214-BB1-6 6.813 2.27E-06 Cat. 3 400 140.9 8-RC-1324-BBl-1 6.813 2.27E-06 Cat. 3 401 142.5 8-RC-1324-BB1-2 6.813 2.27E-06 Cat. 3 402 141.5 S-RC-1324-BB1-3 6.813 2.27E-06 Cat. 3 403 140.4 8-RC-1324-BB1-4 6.813 2.27E-06 Cat. 3 404 136.2 8-RC-1324-BBI-5 6.813 2.27E-06 Cat. 3 405 132.9 8-RC-1324-BB1-6 6.813 2.27E-06 Cat. 3 406 159.1 8-RH-1108-BBI-I 6.813 2.27E-06 Cat. 3 407 158.8 8-RH-1108-BBI-2 6.813 2.27E-06 Cat. 3 408 141.7 8-RH-i 112-BBI-1 6.813 2.27E-06 Cat. 3 409 143.2 8-RH-1112-BB1-1A 6.813 2.27E-06 Cat. 3 410 142.8 8-RH-i 112-BB1-2 6.813 2.27E-06 Cat. 3 411 160.0 8-RH-1208-BBI-1 6.813 2.27E-06 Cat. 3 412 159.8 8-RH-1208-BB1-2 6.813 2.27E-06 Cat. 3 413 141.0 8-RH-1212-BBI-I 6.813 2.27E-06 Cat. 3 414 144.0 8-RH-1212-BB1-2 6.813 2.27E-06 Cat. 3 415 153.1 8-RH-1308-BBI-1 6.813 2.27E-06 Cat. 3 416 154.8 8-RH-1308-BB1-2 6.813 2.27E-06 Cat. 3 417 142.8 8-RH-1315-BB1-1 6.813 2.27E-06 Cat. 3 418 147.9 8-SI-1108-BBI-1 6.813 2.27E-06 Cat. 3 419 144.7 8-SI-1108-BB1-2 6.813 2.27E-06 Cat. 3 420 141.0 8-SI-1108-BB1-3 6.813 2.27E-06 Cat. 3 421 137.1 8-SI-I 108-BB1-4 6.813 2.27E-06 Cat. 3 422 139.8 8-SI-1108-BB1-5 6.813 2.27E-06 Cat. 3 423 148.3 8-SI-1208-BB1-1 6.813 2.27E-06 Cat. 3 424 146.4 8-SI-1208-BB1-2 6.813 2.27E-06 Cat. 3 425 141.8 8-SI-1208-BB1-3 6.813 2.27E-06 Cat. 3 426 137.8 8-SI-1208-BB1-3A 6.813 2.27E-06 Cat. 3 427 140.9 8-SI-1208-BB1-4 6.813 2.27E-06 Cat. 3 428 144.1 8-SI-1327-BBI-1 6.813 2.27E-06 Cat. 3 429 131.3 8-SI-1327-BB1-10 6.813 2.27E-06 Cat. 3 430 137.0 8-SI-1327-BB1-11 6.813 2.27E-06 Cat. 3 431 144.7 8-SI-1327-BB1-2 6.813 2.27E-06 Cat. 3 432 145.0 8-SI-1327-BBI-3 6.813 2.27E-06 Cat. 3 433 145.8 8-SI-1327-BB1-4 6.813 2.27E-06 Cat. 3 434 147.5 8-SI-1327-BBI-5 6.813 2.27E-06 Cat. 3 435 145.6 8-SI-1327-BB1-6 6.813 2.27E-06 Cat. 3 436 141.0 8-SI-1327-BB1-7 6.813 2.27E-06 Cat. 3 437 136.2 8-SI-1327-BBI-8 6.813 2.27E-06 Cat. 3 438 134.9 8-SI-1327-BB1-9 6.813 2.27E-06 Cat. 3 439 157.3 10-RH-1108-BB1-1 8.500 1.30E-06 Cat. 4 440 145.6 10-RH-1108-BB1-10 8.500 1.30E-06 Cat. 4 441 157.0 10-RH-1108-BB1-IA 8.500 1.30E-06 Cat. 4 442 156.9 10-RH-1 108-BB1-2 8.500 1.30E-06 Cat. 4 continued next page ...

Saturday 1 4 th March, 2015, 07:39 29 corresponding: k-eeej(Ostpegs.corn

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 443 156.8 10-RH-1108-BB1-3 8.500 1.30E-06 Cat. 4 444 156.6 10-RH-1108-BB1-4 8.500 1.30E-06 Cat. 4 445 156.6 10-RH-1108-BB1-5 8.500 1.30E-06 Cat. 4 446 156.7 10-RH-1108-BB1-6 8.500 1.30E-06 Cat. 4 447 156.1 10-RH-1108-BBI-7 8.500 1.30E-06 Cat. 4 448 144.8 10-RH-1108-BB1-8 8.500 1.30E-06 Cat. 4 449 145.1 10-RH-1108-BB1-9 8.500 1.30E-06 Cat. 4 450 158.4 10-RH-1208-BBI-I 8.500 1.30E-06 Cat. 4 451 147.0 10-RH-1208-BB1- 10 8.500 1.30E-06 Cat. 4 452 147.9 10-RH-1208-BB1-11 8.500 1.30E-06 Cat. 4 453 158.2 10-RH-1208-BBI-2 8.500 1.30E-06 Cat. 4 454 158.1 10-RH-1208-BB1-3 8.500 1.30E-06 Cat. 4 455 157.5 10-RH-1208-BBI-4 8.500 1.30E-06 Cat. 4 456 157.2 10-RH-1208-BBI-5 8.500 1.30E-06 Cat. 4 457 157.3 10-RH-1208-BB1-6 8.500 1.30E-06 Cat. 4 458 156.5 10-RH-1208-BB1-7 8.500 1.30E-06 Cat. 4 459 146.8 10-R.H-1208-BBI-8 8.500 1.30E-06 Cat. 4 460 146.5 10-RH-1208-BB1-9 8.500 1.30E-06 Cat. 4 461 152.9 10-RH-1308-BBI-I 8.500 1.30E-06 Cat. 4 462 158.4 10-RH-1308-BBI-2 8.500 1.30E-06 Cat. 4 463 158.5 10-RH-1308-BBI-3 8.500 1.30E-06 Cat. 4 464 158.4 10-RH-1308-BBI-4 8.500 1.30E-06 Cat. 4 465 158.6 10-RH-1308-BBI-5 8.500 1.30E-06 Cat. 4 466 157.8 10-RH-1308-BBI-6 8.500 1.30E-06 Cat. 4 467 157.7 10-RH-1308-BBI-7 8.500 1.30E-06 Cat. 4 468 157.3 10-RH-1308-BBI-8 8.500 1.30E-06 Cat. 4 469 94.8 12-RC-1112-BB1-I 10.126 9.75E-07 Cat. 4 470 126.3 12-RC-1112-BB1-10 10.126 9.75E-07 Cat. 4 471 126.1 12-RC-1112-BB1-1 1 10.126 9.75E-07 Cat. 4 472 105.5 12-RC-1112-BBI-2 10.126 9.75E-07 Cat. 4 473 112.0 12-RC-1112-BB1-3 10.126 9.75E-07 Cat. 4 474 116.1 12-RC-1112-BBI-4 10.126 9.75E-07 Cat. 4 475 118.2 12-RC-1112-BBi-5 10.126 9.75E-07 Cat. 4 476 114.8 12-RC-1112-BBI-6 10.126 9.75E-07 Cat. 4 477 112.5 12-RC-1112-BB1-7 10.126 9.75E-07 Cat. 4 478 113.5 12-RC-1112-BB1-8 10.126 9.75E-07 Cat. 4 479 123.3 12-RC-1112-BBI-9 10.126 9.75E-07 Cat. 4 480 143.3 12-RC-1125-BB1-1 10.126 9.75E-07 Cat. 4 481 63.4 12-RC-1 125-BB1-10 10.126 9.75E-07 Cat. 4 482 60.1 12-RC-1125-BB1-11 10.126 9.75E-07 Cat. 4 483 65.9 12-RC-1125-BB1-12 10.126 9.75E-07 Cat. 4 484 90.7 12-RC-1125-BB1-13 10.126 9.75E-07 Cat. 4 485 144.6 12-RC-1 125-BBI-2 10.126 9.75E-07 Cat. 4 486 144.8 12-RC-1125-BB1-3 10.126 9.75E-07 Cat. 4 487 145.1 12-RC-1125-BB1-4 10.126 9.75E-07 Cat. 4 488 145.1 12-RC-1125-BBI-5 10.126 9.75E-07 Cat. 4 continued next page ...

Saturday 14 th March, 2015, 07:39 30 corresponding: keeej Ust pegs. corn

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 489 142.4 12-RC-1125-BB1-6 10.126 9.75E-07 Cat. 4 490 140.8 12-RC-1125-BB1-7 10.126 9.75E-07 Cat. 4 491 95.7 12-RC-1125-BB1-8 10.126 9.75E-07 Cat. 4 492 67.7 12-RC-1125-BB1-9 10.126 9.75E-07 Cat. 4 493 100.2 12-RC-1212-BBI-1 10.126 9.75E-07 Cat. 4 494 108.6 12-RC-1212-BB1-2 10.126 9.75E-07 Cat. 4 495 112.9 12-RC-1212-BB1-3 10.126 9.75E-07 Cat. 4 496 118.6 12-RC-1212-BB1-4 10.126 9.75E-07 Cat. 4 497 120.0 12-RC-1212-BB1-5 10.126 9.75E-07 Cat. 4 498 115.5 12-RC-1212-BB1-6 10.126 9.75E-07 Cat. 4 499 113.6 12-RC-1212-BB1-7 10.126 9.75E-07 Cat. 4 500 107.8 12-RC-1212-BB1-8 10.126 9.75E-07 Cat. 4 501 146.4 12-RC-1221-BBl-1 10.126 9.75E-07 Cat. 4 502 64.1 12-RC-1221-BBl-10 10.126 9.75E-07 Cat. 4 503 54.5 12-RC-1221-BB1-11 10.126 9.75E-07 Cat. 4 504 62.7 12-RC-1221-BBl-12 10.126 9.75E-07 Cat. 4 505 68.5 12-RC-1221-BBl-13 10.126 9.75E-07 Cat. 4 506 94.2 12-RC-1221-BB1-14 10.126 9.75E-07 Cat. 4 507 147.3 12-RC-1221-BB1-2 10.126 9.75E-07 Cat. 4 508 146.9 12-RC-1221-BB1-3 10.126 9.75E-07 Cat. 4 509 145.8 12-RC-1221-BB1-4 10.126 9.75E-07 Cat. 4 510 144.3 12-RC-1221-BB1-5 10.126 9.75E-07 Cat. 4 511 142.3 12-RC-1221-BB1-6 10.126 9.75E-07 Cat. 4 512 141.0 12-RC-1221-BB1-7 10.126 9.75E-07 Cat. 4 513 100.5 12-RC-1221-BB1-8 10.126 9.75E-07 Cat. 4 514 67.8 12-RC-1221-BB1-9 10.126 9.75E-07 Cat. 4 515 99.9 12-RC-1312-BBI-1 10.126 9.75E-07 Cat. 4 516 119.3 12-RC-1312-BB1-10 10.126 9.75E-07 Cat. 4 517 120.0 12-RC-1312-BB1-11 10.126 9.75E-07 Cat. 4 518 108.1 12-RC-1312-BB1-2 10.126 9.75E-07 Cat. 4 519 112.5 12-RC-1312-BB1-3 10.126 9.75E-07 Cat. 4 520 118.1 12-RC-1312-BB1-4 10.126 9.75E-07 Cat. 4 521 119.6 12-RC-1312-BB1-5 10.126 9.75E-07 Cat. 4 522 115.0 12-RC-1312-BB1-6 10.126 9.75E-07 Cat. 4 523 113.4 12-RC-1312-BB1-7 10.126 9.75E-07 Cat. 4 524 103.4 12-R.C-1312-BB1-8 10.126 9.75E-07 Cat. 4 525 117.5 12-RC-1312-BB1-9 10.126 9.75E-07 Cat. 4 526 61.0 12-RC-1322-BBl-1 10.126 9.75E-07 Cat. 4 527 61.1 12-RC-1322-BB1-1A 10.126 9.75E-07 Cat. 4 528 65.4 12-RC-1322-BBI-2 10.126 9.75E-07 Cat. 4 529 70.3 12-RC-1322-BB1-3 10.126 9.75E-07 Cat. 4 530 94.6 12-RC-1322-BB1-4 10.126 9.75E-07 Cat. 4 531 125.4 12-RH-1101-BBI-1 10.126 9.75E-07 Cat. 4 532 147.3 12-RH-1101-BBI-10 10.126 9.75E-07 Cat. 4 533 148.4 12-RH-1101-BB1-11 10.126 9.75E-07 Cat. 4 534 152.6 12-RH-1101-BBI-12 10.126 9.75E-07 Cat. 4 continued next page ...

Saturday 14 th March, 2015, 07:39 31 corresponding: keeejOlstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 535 148.8 12-RH-1101-BB1-13 10.126 9.75E-07 Cat. 4 536 151.7 12-RH-1 101-BB1-14 10.126 9.75E-07 Cat. 4 537 151.9 12-RH-1 101-BBI-15 10.126 9.75E-07 Cat. 4 538 150.9 12-RH-1101-BB1-16 10.126 9.75E-07 Cat. 4 539 128.7 12-RH-1101-BB1-2 10.126 9.75E-07 Cat. 4 540 127.5 12-RH-1101-BB1-3 10.126 9.75E-07 Cat. 4 541 109.5 12-RH-1101-BB1-3A 10.126 9.75E-07 Cat. 4 542 112.3 12-RH-1101-BB1-4 10.126 9.75E-07 Cat. 4 543 121.2 12-RH-1101-BB1-5 10.126 9.75E-07 Cat. 4 544 122.0 12-RH- 110 1-BB 1-6 10.126 9.75E-07 Cat. 4 545 121.5 12-RH-i 101-BB1-7 10.126 9.75E-07 Cat. 4 546 127.8 12-RH-1101-BB1-8 10.126 9.75E-07 Cat. 4 547 148.7 12-RH-1101-BB1-9 10.126 9.75E-07 Cat. 4 548 113.8 12-RH-1201-BBI-1 10.126 9.75E-07 Cat. 4 549 124.0 12-RH-1201-BBI-10 10.126 9.75E-07 Cat. 4 550 145.9 12-RH-1201-BBI-11 10.126 9.75E-07 Cat. 4 551 147.7 12-RH-1201-BBl-12 10.126 9.75E-07 Cat. 4 552 148.1 12-RH-1201-BBI-13 10.126 9.75E-07 Cat. 4 553 151.0 12-RH-1201-BBI-14 10.126 9.75E-07 Cat. 4 554 153.7 12-RH-1201-BBI-15 10.126 9.75E-07 Cat. 4 555 153.4 12-RH-1201-BBI-16 10.126 9.75E-07 Cat. 4 556 152.8 12-RH-1201-BB1-17 10.126 9.75E-07 Cat. 4 557 118.7 12-RH-1201-BB1-2 10.126 9.75E-07 Cat. 4 558 122.5 12-RH-1201-BB1-3 10.126 9.75E-07 Cat. 4 559 123.1 12-RH-1201-BBi-4 10.126 9.75E-07 Cat. 4 560 122.6 12-RH-1201-BB1-5 10.126 9.75E-07 Cat. 4 561 108.3 12-RH-1201-BBi-6 10.126 9.75E-07 Cat. 4 562 117.8 12-RH-1201-BB1-7 10.126 9.75E-07 Cat. 4 563 118.5 12-RH-1201-BBI-8 10.126 9.75E-07 Cat. 4 564 117.3 12-RH-1201-BBi-9 10.126 9.75E-07 Cat. 4 565 123.3 12-RH-1301-BBl-1 10.126 9.75E-07 Cat. 4 566 150.8 12-RH-1301-BBI-10 10.126 9.75E-07 Cat. 4 567 125.6 12-RH-1301-BB1-2 10.126 9.75E-07 Cat. 4 568 125.8 12-RH-1301-BB1-3 10.126 9.75E-07 Cat. 4 569 123.5 12-RH-1301-BBI-4 10.126 9.75E-07 Cat. 4 570 127.4 12-RH-1301-BB1-5 10.126 9.75E-07 Cat. 4 571 149.1 12-RH-1301-BB1-5A 10.126 9.75E-07 Cat. 4 572 148.8 12-RH-1301-BB1-6 10.126 9.75E-07 Cat. 4 573 148.9 12-RH-1301-BBI-7 10.126 9.75E-07 Cat. 4 574 150.4 12-RH-1301-BB1-8 10.126 9.75E-07 Cat. 4 575 150.8 12-RH-1301-BB1-9 10.126 9.75E-07 Cat. 4 576 146.8 12-SI-1125-BBl-1 10.126 9.75E-07 Cat. 4 577 144.5 12-SI-1125-BB1-2 10.126 9.75E-07 Cat. 4 578 144.0 12-SI-1125-BB1-3 10.126 9.75E-07 Cat. 4 579 143.9 12-SI- 1125-BB1-4 10.126 9.75E-07 Cat. 4 580 149.3 12-SI-1218-BBI-I 10.126 9.75E-07 Cat. 4 continued next page ...

Saturday 1 4 th March, 2015, 07:39 32 corresponding: keeej@stpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 581 147.2 12-SI-1218-BB1-2 10.126 9.75E-07 Cat. 4 582 146.6 12-SI-1218-BB1-3 10.126 9.75E-07 Cat. 4 583 146.4 12-SI-1218-BB1-4 10.126 9.75E-07 Cat. 4 584 156.3 12-SI-1315-BB1-1 10.126 9.75E-07 Cat. 4 585 70.7 12-SI-1315-BB1-10 10.126 9.75E-07 Cat. 4 586 155.8 12-SI-1315-BB1-2 10.126 9.75E-07 Cat. 4 587 155.2 12-SI-1315-BB1-3 10.126 9.75E-07 Cat. 4 588 155.3 12-SI-1315-BB1-4 10.126 9.75E-07 Cat. 4 589 155.5 12-SI-1315-BB1-5 10.126 9.75E-07 Cat. 4 590 117.8 12-SI-1315-BB1-6 10.126 9.75E-07 Cat. 4 591 91.1 12-SI-1315-BB1-7 10.126 9.75E-07 Cat. 4 592 79.2 12-SI-1315-BB1-8 10.126 9.75E-07 Cat. 4 593 74.7 12-SI-1315-BB1-9 10.126 9.75E-07 Cat. 4 594 116.2 27.5-RC-1103-NSS-4 10.126 9.75E-07 Cat. 4 595 105.5 27.5-RC-1203-NSS-3 10.126 9.75E-07 Cat. 4 596 104.6 27.5-RC-1303-NSS-3 10.126 9.75E-07 Cat. 4 597 93.4 29-RC-1101-NSS-3 10.126 9.75E-07 Cat. 4 598 95.8 29-RC-1201-NSS-3 10.126 9.75E-07 Cat. 4 599 96.4 29-RC-1301-NSS-3 10.126 9.75E-07 Cat. 4 600 97.4 16-RC-1412-NSS-1 12.814 4.37E-07 Cat. 4 601 147.9 16-RC-1412-NSS-3 12.814 4.37E-07 Cat. 4 602 150.9 16-RC-1412-NSS-4 12.814 4.37E-07 Cat. 4 603 77.8 16-RC-1412-NSS-5 12.814 4.37E-07 Cat. 4 604 59.0 16-RC-1412-NSS-6 12.814 4.37E-07 Cat. 4 605 48.3 16-RC-1412-NSS-7 12.814 4.37E-07 Cat. 4 606 21.4 16-RC-1412-NSS-9 12.814 4.37E-07 Cat. 4 607 96.5 16-RC-1412-NSS-PRZ-1-N1-SE 12.814 4.37E-07 Cat. 4 608 22.6 29-RC-1401-NSS-2 12.814 4.37E-07 Cat. 4 609 49.4 27.5-RC-1103-NSS-6 27.500 6.42E-08 Cat. 5 610 50.4 27.5-RC-1103-NSS-7 27.500 6.42E-08 Cat. 5 611 48.3 27.5-RC-1103-NSS-RPVI-N2ASE 27.500 6.42E-08 Cat. 5 612 50.6 27.5-RC-1203-NSS-4 27.500 6.42E-08 Cat. 5 613 51.1 27.5-RC- 1203-NSS-5 27.500 6.42E-08 Cat. 5 614 50.5 27.5-RC-1203-NSS-RPV1-N2BSE 27.500 6.42E-08 Cat. 5 615 67.0 27.5-RC-1303-NSS-5 27.500 6.42E-08 Cat. 5 616 64.2 27.5-RC-1303-NSS-6 27.500 6.42E-08 Cat. 5 617 63.6 27.5-RC- 1303-NSS-RPV1-N2CSE 27.500 6.42E-08 Cat. 5 618 74.3 27.5-RC-1403-NSS-5 27.500 6.42E-08 Cat. 5 619 69.4 27.5-RC-1403-NSS-6 27.500 6.42E-08 Cat. 5 620 68.3 27.5-RC-1403-NSS-RPV1-N2DSE 27.500 6.42E-08 Cat. 5 621 25.2 29-RC-1101-NSS-1 29.000 4.91E-08 Cat. 5 622 23.6 29-RC-1 101-NSS-RPV1-N 1ASE 29.000 4.91E-08 Cat. 5 623 22.3 29-RC-1201-NSS-1 29.000 4.91E-08 Cat. 5 624 19.3 29-RC-1201-RPV1-NIBSE 29.000 4.91 E-08 Cat. 5 625 23.8 29-RC-1301-NSS-1 29.000 4.91E-08 Cat. 5 626 21.5 29-RC-1301-RPV1-N 1CSE 29.000 4.91E-08 Cat. 5 continued next page ...

Saturday 1 4 th March, 2015, 07:39 33 corresponding: keeejOcIstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 627 23.8 29-RC-1401-NSS-1 29.000 4.91E-08 Cat. 5 628 20.9 29-RC-1401-NSS-RPV1-N1DSE 29.000 4.91E-08 Cat. 5 Table 10: Single train data for weld locations in the risk-informed category listing the jth weld number, mass of fiber in the sump for the scenario (lbm), location name (ID), Break size (Size), scenario frequency, fi (mean quantile, geometric aggregation), and NUREG 1829 data category No. Amount (Ibm) Location Size (in) fi NUREG 1829 Cat.

1 95.96 29-RC-1301-RSG-1C-IN-SE 9.28 1.14E-06 Cat. 4 2 96.13 29-RC-1101-NSS-5.1 9.31 1.14E-06 Cat. 4 3 96.83 29-RC-1101-NSS-RSG-1A-IN-SE 9.33 1.13E-06 Cat. 4 4 96.17 29-RC-1201-RSG-1B-IN-SE 9.35 1.13E-06 Cat. 4 5 96.74 29-RC-1301-NSS-5.1 9.35 1.13E-06 Cat. 4 6 95.99 29-RC-1201-NSS-5.1 9.35 1.13E-06 Cat. 4 7 96.34 29-RC-1401-NSS-RSC-1D-IN-SE 9.38 1.12E-06 Cat. 4 8 96.55 29-RC-1401-NSS-4.1 9.41 1.12E-06 Cat. 4 9 95.96 31-RC-1102-NSS-RSC-1A-ON-SE 9.81 1.04E-06 Cat. 4 10 96.35 31-RC-1202-NSS-1.1 9.86 1.03E-06 Cat. 4 11 96.66 31-RC-1102-NSS-1.1 9.86 1.03E-06 Cat. 4 12 96.48 31-RC-1202-NSS-RSG-1B-ON-SE 9.87 1.03E-06 Cat. 4 13 96.13 31-RC-1202-NSS-2 10.03 9.94E-07 Cat. 4 14 95.97 31-RC-1302-NSS-1.1 10.10 9.80E-07 Cat. 4 15 96.07 31-RC-1302-NSS-RSC-1C-ON-SE 10.11 9.79E-07 Cat. 4 17 96.26 12-RC-1112-BBI-1 10.13 9.75E-07 Cat. 4 18 96.96 12-RC-1125-BBl-10 10.13 9.75E-07 Cat. 4 19 128.39 12-RC.-1125-BB1-11 10.13 9.75E-07 Cat. 4 20 131.64 12-RC-1125-BBl-12 10.13 9.75E-07 Cat. 4 21 125.93 12-RC-1125-BBl-13 10.13 9.75E-07 Cat. 4 22 101.10 12-RC-1125-BB1-8 10.13 9.75E-07 Cat. 4 23 96.07 12-RC-1125-BB1-9 10.13 9.75E-07 Cat. 4 24 124.08 12-RC-1221-BBl-10 10.13 9.75E-07 Cat. 4 25 127.70 12-RC-1221-BB1-11 10.13 9.75E-07 Cat. 4 26 137.30 12-RC-1221-BBl-12 10.13 9.75E-07 Cat. 4 27 129.09 12-RC-1221-BBl-13 10.13 9.75E-07 Cat. 4 28 123.32 12-RC-1221-BBl-14 10.13 9.75E-07 Cat. 4 29 97.57 12-RC-1221-BBI-9 10.13 9.75E-07 Cat. 4 30 123.96 12-RC-1322-BBl-1 10.13 9.75E-07 Cat. 4 31 130.82 12-RC-1322-BB1-lA 10.13 9.75E-07 Cat. 4 32 130.73 12-RC-1322-BB1-2 10.13 9.75E-07 Cat. 4 33 126.33 12-RC-1322-BB1-3 10.13 9.75E-07 Cat. 4 34 121.46 12-RC-1322-BB1-4 10.13 9.75E-07 Cat. 4 35 97.21 12-SI-1315-BBI-10 10.13 9.75E-07 Cat. 4 36 121.12 12-SI-1315-BBI-7 10.13 9.75E-07 Cat. 4 37 100.67 12-SI-1315-BB1-8 10.13 9.75E-07 Cat. 4 38 112.56 12-SI-1315-BB1-9 10.13 9.75E-07 Cat. 4 continued next page ...

Saturday 14 th March, 2015, 07:39 34 corresponding: keeej@stpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Amount (Ibm) Location Size (in) fi NUREG 1829 Cat.

39 117.11 29-RC-1101-NSS-3 10.13 9.75E-07 Cat. 4 40 98.43 29-RC-1201-NSS-3 10.13 9.75E-07 Cat. 4 16 96.01 31-RC-1102-NSS-2 10.13 9.75E-07 Cat. 4 41 96.35 16-RC-1412-NSS-8 10.21 9.59E-07 Cat. 4 42 96.44 31-RC-1302-NSS-2 10.30 9.40E-07 Cat. 4 43 95.90 29-RC-1101-NSS-4 10.45 9.10E-07 Cat. 4 44 96.00 31-RC-1402-NSS-1.1 10.50 9.OOE-07 Cat. 4 45 96.14 31-RC-1402-NSS-RSG-1D-ON-SE 10.51 8.98E-07 Cat. 4 46 96.07 29-RC-1401-NSS-3 10.63 8.75E-07 Cat. 4 47 96.14 29-RC-1301-NSS-4 10.63 8.74E-07 Cat. 4 48 96.38 29-RC-1201-NSS-4 10.67 8.67E-07 Cat. 4 49 96.05 31-RC-1402-NSS-2 11.08 7.83E-07 Cat. 4 50 95.97 31-RC-1202-NSS-3 11.15 7.71E-07 Cat. 4 51 96.37 16-RC-1412-NSS-9 11.17 7.66E-07 Cat. 4 52 95.99 29-RC-1401-NSS-2 11.17 7.66E-07 Cat. 4 53 95.90 31-RC-1302-NSS-3 11.31 7.38E-07 Cat. 4 54 96.15 31-RC-1102-NSS-3 11.39 7.22E-07 Cat. 4 55 95.98 31-RC-1202-NSS-4 11.50 7.OOE-07 Cat. 4 56 95.90 31-RC-1102-NSS-4 11.62 6.76E-07 Cat. 4 57 95.93 31-RC-1302-NSS-4 11.74 6.52E-07 Cat. 4 58 96.08 31-RC-1202-NSS-8 11.76 6.49E-07 Cat. 4 59 95.91 31-RC-1102-NSS-8 11.90 6.19E-07 Cat. 4 60 95.92 31-RC-1302-NSS-8 12.30 5.40E-07 Cat. 4 61 96.05 31-RC-1402-NSS-3 12.43 5.14E-07 Cat. 4 62 95.92 31-RC-1202-NSS-9 12.56 4.88E-07 Cat. 4 63 95.95 27.5-RC-1103-NSS-1 12.75 4.50E-07 Cat. 4 64 113.96 16-RC-1412-NSS-5 12.81 4.37E-07 Cat. 4 65 132.76 16-RC-1412-NSS-6 12.81 4.37E-07 Cat. 4 66 143.52 16-RC-1412-NSS-7 12.81 4.37E-07 Cat. 4 67 95.90 27.5-RC-1203-NSS-1 12.82 4.36E-07 Cat. 4 68 95.94 31-RC-1102-NSS-9 12.83 4.34E-07 Cat. 4 69 96.03 31-RC-1402-NSS-4 13.26 3.48E-07 Cat. 4 70 95.95 27.5-RC-1303-NSS-1 13.68 2.64E-07 Cat. 4 71 95.93 31-RC-1302-NSS-9 13.95 2.1OE-07 Cat. 4 72 97.33 31-RC-1402-NSS-8 14.45 1.LOE-07 Cat. 4 73 96.02 27.5-RC-1403-NSS-1 14.72 5.62E-08 Cat. 4 74 97.16 31-RC-1402-NSS-9 16.33 1.77E-07 Cat. 5 75 142.33 27.5-RC-1103-NSS-6 27.50 6.42E-08 Cat. 5 76 141.38 27.5-RC-1103-NSS-7 27.50 6.42E-08 Cat. 5 77 143.44 27.5-RC-1 103-NSS-RPVI-N2ASE 27.50 6.42E-08 Cat. 5 78 141.23 27.5-RC-1203-NSS-4 27.50 6.42E-08 Cat. 5 79 140.65 27.5-RC-1203-NSS-5 27.50 6.42E-08 Cat. 5 80 141.24 27.5-RC-1203-NSS-RPV1-N2BSE 27.50 6.42E-08 Cat. 5 81 124.75 27.5-RC-1303-NSS-5 27.50 6.42E-08 Cat. 5 82 127.56 27.5-RC-1303-NSS-6 27.50 6.42E-08 Cat. 5 83 128.16 27.5-RC- 1303-NSS-RPV1-N2CSE 27.50 6.42E-08 Cat. 5 84 117.48 27.5-RC-1403-NSS-5 27.50 6.42E-08 Cat. 5 continued next page ...

Saturday 1 4 th March, 2015, 07:39 35 corresponding: keeejUstpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Amount (Ibm) Location Size (in) fi NUREG 1829 Cat.

85 122.40 27.5-R.C-1403-NSS-6 27.50 6.42E-08 Cat. 5 86 123.45 27.5-RC-1403-NSS-RPV1-N2DSE 27.50 6.42E-08 Cat. 5 87 166.58 29-RC-1101-NSS-1 29.00 4.91E-08 Cat. 5 88 168.16 29-RC-1101-NSS-RPV1-N1ASE 29.00 4.91E-08 Cat. 5 89 169.49 29-RC-1201-NSS-1 29.00 4.91E-08 Cat. 5 90 172.48 29-RC-1201-R.PV1-N1BSE 29.00 4.91E-08 Cat. 5 91 167.99 29-RC-1301-NSS-1 29.00 4.91E-08 Cat. 5 92 170.23 29-RC-1301-RPV1-N1CSE 29.00 4.91E-08 Cat. 5 93 168.01 29-RC-1401-NSS-1 29.00 4.91E-08 Cat. 5 94 170.85 29-RC-1401-NSS-RPV1-NlDSE 29.00 4.91E-08 Cat. 5 Table 11: Single train DEGB data (largest break size) for weld locations in the deterministic category showing listing the ith weld number, the margin to tile mass of fiber in the sump produced to the tested amount (Ibm), location name, Break size (Size), scenario DEGB frequency, fi (mean quantile, geometric aggregation), and NUREG 1829 data category No. Margin (lbm) Location DEGB fi NUREG 1829 Cat.

Size (in) 95 67.3 0.75-CV-1122-BB1-1 0.614 1.75E-03 Cat. 1 96 67.3 0.75-CV-1122-BB1-2 0.614 1.75E-03 Cat. 1 97 67.4 0.75-CV-1124-BBl-1 0.614 1.75E-03 Cat. 1 98 67.4 0.75-CV-1124-BB1-2 0.614 1.75E-03 Cat. 1 99 67.4 0.75-CV-1126-BB1-1 0.614 1.75E-03 Cat. 1 100 67.2 0.75-CV-1126-BB1-2 0.614 1.75E-03 Cat. 1 101 67.4 0.75-CV-1128-BBl-1 0.614 1.75E-03 Cat. 1 102 67.4 0.75-CV-1128-BB1-2 0.614 1.75E-03 Cat. 1 103 67.2 0.75-RC-1001-BB1-1 0.614 1.75E-03 Cat. 1 104 67.1 0.75-RC-1002-BB2-1 0.614 1.75E-03 Cat. 1 105 67.1 0.75-RC-1112-BBl-1 0.614 1.75E-03 Cat. 1 106 67.0 0.75-RC-1114-BBI-1 0.614 1.75E-03 Cat. 1 107 67.1 0.75-RC-1125-BBl-1 0.614 1.75E-03 Cat. 1 108 67.0 0.75-RC-1125-BB1-2 0.614 1.75E-03 Cat. 1 109 67.1 0.75-RC-1126-BBl-1 0.614 1.75E-03 Cat. 1 110 67.1 0.75-RC-1212-BBl-1 0.614 1.75E-03 Cat. 1 111 67.0 0.75-RC-1214-BBl-1 0.614 1.75E-03 Cat. 1 112 67.1 0.75-RC-1221-BBl-1 0.614 1.75E-03 Cat. 1 113 67.1 0.75-RC-1221-BB1-2 0.614 1.75E-03 Cat. 1 114 67.1 0.75-RC-1312-BB1-1 0.614 1.75E-03 Cat. 1 115 67.0 0.75-RC-1324-BBl-1 0.614 1.75E-03 Cat. 1 116 67.1 0.75-RC-1423-BBl-1 0.614 1.75E-03 Cat. 1 117 67.2 0.75-SI-1130-BB2-1 0.614 1.75E-03 Cat. 1 118 67.2 0.75-SI-1132-BB1-1 0.614 1.75E-03 Cat. 1 119 67.2 0.75-SI-1218-BB1-1 0.614 1.75E-03 Cat. 1 120 67.2 0.75-SI-1223-BB2-1 0.614 1.75E-03 Cat. 1 121 67.0 0.75-SI-1315-BB1-1 0.614 1.75E-03 Cat. 1 122 67.3 0.75-Sl-1323-BBI-1 0.614 1.75E-03 Cat. I continued next page ...

Saturday 14 1h March, 2015, 07:39 36 corresponding: keeej(ýc-bstpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 123 67.2 0.75-SI-1327-BBI-1 0.614 1.75E-03 Cat. 1 124 67.2 0.75-SI-1327-BB1-2 0.614 1.75E-03 Cat. 1 125 67.2 0.75-SI-1327-BB1-3 0.614 1.75E-03 Cat. 1 126 67.2 0.75-SI-1328-BB2-1 0.614 1.75E-03 Cat. 1 127 66.8 1-RC-1003-BB1-1 0.815 1.49E-03 Cat. 1 128 67.1 1-RC-1123-BBl-1 0.815 1.49E-03 Cat. 1 129 67.0 1-RC-1422-BB1-1 0.815 1.49E-03 Cat. I 130 65.7 1.5-RC-1412-NSS-1 1.338 7.98E-04 Cat. 1 131 67.3 2(1.5)-CV-1122-BB1-1 1.338 7.98E-04 Cat. 1 132 67.1 2(1.5)-CV-1122-BB1-2 1.338 7.98E-04 Cat. 1 133 67.3 2(1.5)-CV-1124-BB1-1 1.338 7.98E-04 Cat. 1 134 67.0 2(1.5)-CV-1124-BB1-2 1.338 7.98E-04 Cat. 1 135 66.9 2(1.5)-CV-1126-BB1-1 1.338 7.98E-04 Cat. 1 136 66.9 2(1.5)-CV-1126-BB1-2 1.338 7.98E-04 Cat. 1 137 67.1 2(1.5)-CV-1128-BB1-1 1.338 7.98E-04 Cat. 1 138 66.9 2(1.5)-CV-1128-BB1-2 1.338 7.98E-04 Cat. 1 139 67.2 2-CV-1121-BBi-1 1.689 4.01E-04 Cat. 2 140 66.9 2-CV-1121-BBI-2 1.689 4.01E-04 Cat. 2 141 66.8 2-CV-1121-BB1-3 1.689 4.01E-04 Cat. 2 142 66.6 2-CV-1122-BB1-1 1.689 4.01E-04 Cat. 2 143 66.7 2-CV-1122-BB1-2 1.689 4.01E-04 Cat. 2 144 66.7 2-CV-1122-BB1-3 1.689 4.01E-04 Cat. 2 145 66.7 2-CV-1122-BB1-4 1.689 4.01E-04 Cat. 2 146 66.7 2-CV-1122-BB1-5 1.689 4.01E-04 Cat. 2 147 67.0 2-CV-1122-BB1-6 1.689 4.01E-04 Cat. 2 148 66.7 2-CV-1124-BBl-1 1.689 4.01E-04 Cat. 2 149 66.6 2-CV-1124-BB1-10 1.689 4.01E-04 Cat. 2 150 66.6 2-CV-1124-BBl-11 1.689 4.01E-04 Cat. 2 151 67.1 2-CV-1124-BBi-12 1.689 4.01E-04 Cat. 2 152 67.0 2-CV-1124-BB1-13 1.689 4.01E-04 Cat. 2 153 66.7 2-CV-1124-BB1-2 1.689 4.01E-04 Cat. 2 154 66.7 2-CV-1124-BB1-3 1.689 4.01E-04 Cat. 2 155 66.6 2-CV-1124-BB1-4 1.689 4.01E-04 Cat. 2 156 66.6 2-CV-1124-BB1-5 1.689 4.01E-04 Cat. 2 157 66.7 2-CV-1124-BB1-6 1.689 4.01E-04 Cat. 2 158 66.8 2-CV-1124-BB1-7 1.689 4.01E-04 Cat. 2 159 66.7 2-CV-1124-BB1-8 1.689 4.01E-04 Cat. 2 160 66.7 2-CV-I 124-BB1-9 1.689 4.01E-04 Cat. 2 161 67.2 2-CV-1126-BBl-1 1.689 4.01E-04 Cat. 2 162 66.5 2-CV-1126-BBl-10 1.689 4.01E-04 Cat. 2 163 66.6 2-CV-1126-BB1-11 1.689 4.01E-04 Cat. 2 164 67.2 2-CV-1126-BB1-2 1.689 4.01E-04 Cat. 2 165 67.1 2-CV-1126-BB1-3 1.689 4.01E-04 Cat. 2 166 67.0 2-CV-1126-BB1-4 1.689 4.01E-04 Cat. 2 167 67.0 2-CV-1126-BB1-5 1.689 4.01E-04 Cat. 2 168 67.0 2-CV-1126-BB1-6 1.689 4.01E-04 Cat. 2 continued next page ...

Saturday 14 th March, 2015, 07:39 37 corresponding: keeej Ccbstpegs. coin

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages continued No. Margin (Ibm) Location DECB fi NUREG 1829 Cat.

Size (in) 169 66.9 2-CV-1126-BB1-7 1.689 4.01E-04 Cat. 2 170 66.0 2-CV-1126-BB1-8 1.689 4.01E-04 Cat. 2 171 65.9 2-CV-1126-BB1-9 1.689 4.01E-04 Cat. 2 172 67.4 2-CV-1128-BBl-1 1.689 4.01E-04 Cat. 2 173 67.2 2-CV-1128-BB1-2 1.689 4.01E-04 Cat. 2 174 67.1 2-CV-1128-BB1-3 1.689 4.01E-04 Cat. 2 175 67.1 2-CV-1128-BBI-3A 1.689 4.01E-04 Cat. 2 176 67.0 2-CV-1128-BBl-3B 1.689 4.01E-04 Cat. 2 177 67.0 2-CV-1128-BB1-4 1.689 4.01E-04 Cat. 2 178 67.0 2-CV-1128-BB1-5 1.689 4.01E-04 Cat. 2 179 67.1 2-CV-1128-BB1-6 1.689 4.01E-04 Cat. 2 180 66.9 2-CV-1128-BB1-7 1.689 4.01E-04 Cat. 2 181 66.9 2-CV-1141-BBI-1 1.689 4.01E-04 Cat. 2 182 67.1 2-CV-1141-BB1-2 1.689 4.01E-04 Cat. 2 183 66.8 2-RC-1003-BBI-1 1.689 4.01E-04 Cat. 2 184 66.5 2-RC-1003-BB1-2 1.689 4.01E-04 Cat. 2 185 66.1 2-RC-1120-BBI-1 1.689 4.01E-04 Cat. 2 186 66.3 2-RC-1120-BB1-2 1.689 4.01E-04 Cat. 2 187 65.7 2-RC-1121-BBI-1 1.689 4.01E-04 Cat. 2 188 66.8 2-RC-1121-BB1-2 1.689 4.01E-04 Cat. 2 189 66.8 2-RC-1121-BBI-3 1.689 4.01E-04 Cat. 2 190 66.8 2-RC-1121-BB1-3A 1.689 4.01E-04 Cat. 2 191 66.9 2-RC-1 121-BB1-3B 1.689 4.01E-04 Cat. 2 192 67.0 2-RC-1121-BB1-4 1.689 4.01E-04 Cat. 2 193 66.0 2-RC-1219-BBI-1 1.689 4.01E-04 Cat. 2 194 66.2 2-RC-1219-BB1-2 1.689 4.01E-04 Cat. 2 195 65.7 2-RC-1220-BBl-1 1.689 4.01E-04 Cat. 2 196 66.9 2-RC-1220-BB1-2 1.689 4.01E-04 Cat. 2 197 66.9 2-RC-1220-BB1-3 1.689 4.01E-04 Cat. 2 198 67.0 2-RC-1220-BBI-4 1.689 4.01E-04 Cat. 2 199 65.9 2-RC-1319-BB1-1 1.689 4.01E-04 Cat. 2 200 66.3 2-RC-1319-BB1-2 1.689 4.01E-04 Cat. 2 201 66.3 2-RC-1321-BB1-1 1.689 4.01E-04 Cat. 2 202 66.5 2-RC-1321-BB1-4 1.689 4.01E-04 Cat. 2 203 66.5 2-RC-1321-BB1-5 1.689 4.01E-04 Cat. 2 204 66.6 2-RC-1321-BB1-6 1.689 4.01E-04 Cat. 2 205 66.1 2-RC-1417-BB1-1 1.689 4.01E-04 Cat. 2 206 66.3 2-RC-1417-BB1-2 1.689 4.01E-04 Cat. 2 207 65.7 2-RC-1418-BB1-1 1.689 4.01E-04 Cat. 2 208 66.3 2-RC-1418-BBI-2 1.689 4.01E-04 Cat. 2 209 66.4 2-RC-1418-BB1-3 1.689 4.01E-04 Cat. 2 210 66.4 2-RC-1418-BB1-4 1.689 4.01E-04 Cat. 2 211 66.6 2-RC-1418-BB1-5 1.689 4.01E-04 Cat. 2 212 66.7 2-RC-1418-BB1-6 1.689 4.01E-04 Cat. 2 213 66.4 2-RC-1419-BBI-1 1.689 4.01E-04 Cat. 2 214 66.6 2-R.C-1419-BB1-2 1.689 4.01E-04 Cat. 2 continued next page ...

38 corresponding: keeej~istpegs.com March, 2015, 07:39 1 4 th March, 2015, 07:39 Saturday 14"' 38 corresponding: keeej (Cost pegs. com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 215 66.6 2-RC-1419-BB1-3 1.689 4.01E-04 Cat. 2 216 66.9 2-RC-1419-BB1-4 1.689 4.01lE-04 Cat. 2 217 65.9 31-RC- I102-NSS-5 1.689 4.01E-04 Cat. 2 218 65.6 31-RC-1102-NSS-6 1.689 4.01E-04 Cat. 2 219 65.9 31-RC-1202-NSS-5 1.689 4.01E-04 Cat. 2 220 65.5 31-RC-1202-NSS-7 1.689 4.01E-04

• Cat. 2 221 65.8 31-RC-1302-NSS-5 1.689 4.01E-04 Cat. 2 222 65.9 31-RC-1402-NSS-5 1.689 4.01E-04 Cat. 2 223 65.6 31-RC-1402-NSS-7 1.689 4.01E-04 Cat. 2 224 65.5 2.5-RC-1003-BBl-1 2.125 2.73E-04 Cat. 2 225 65.6 2.5-RC-1003-BB1-2 2.125 2.73E-04 Cat. 2 226 65.7 2.5-RC-1003-BB1-3 2.125 2.73E-04 Cat. 2 227 65.7 2.5-RC-1003-BB1-4 2.125 2.73E-04 Cat. 2 228 65.7 2.5-RC-1003-BB1-5 2.125 2.73E-04 Cat. 2 229 65.8 2.5-RC-1003-BB1-6 2.125 2.73E-04 Cat. 2 230 63.0 31-RC-1102-NSS-7 2.626 1.26E-04 Cat. 2 231 63.0 31-RC-1202-NSS-6 2.626 1.26E-04 Cat. 2 232 63.0 31-RC-1302-NSS-6 2.626 1 .26E-04 Cat. 2 233 63.0 31-RC-1402-NSS-6 2.626 1.26E-04 Cat. 2 234 65.2 3-RC-1003-BB1-1 2.626 1 .26E-04 Cat. 2 235 65.3 3-RC-1003-BB1-2 2.626 1.26E-04 Cat. 2 236 65.3 3-RC-1015-NSS-1 2.626 1.26E-04 Cat. 2 237 64.7 3-RC-1015-NSS-10 2.626 1 .26E-04 Cat. 2 238 64.8 3-RC-1015-NSS-11 2.626 1 .26E-04 Cat. 2 239 65.3 3-RC-1015-NSS-12 2.626 1 .26E-04 Cat. 2 240 66.0 3-RC-1015-NSS-13 2.626 1.26E-04 Cat. 2 241 67.1 3-RC-1015-NSS-14 2.626 1.26E-04 Cat. 2 242 67.2 3-RC-1015-NSS-15 2.626 1.26E-04 Cat. 2 243 66.2 3-RC-1015-NSS-16 2.626 1.26E-04 Cat. 2 244 65.5 3-RC-1015-NSS-2 2.626 1.26E-04 Cat. 2 245 65.7 3-RC-1015-NSS-3 2.626 1.26E-04 Cat. 2 246 66.3 3-RC-1015-NSS-4 2.626 1.26E-04 Cat. 2 247 66.8 3-RC-1015-NSS-5 2.626 1 .26E-04 Cat. 2 248 67.3 3-RC-1015-NSS-6 2.626 1.26E-04 Cat. 2 249 67.4 3-RC-1015-NSS-7 2.626 1.26E-04 Cat. 2 250 67.4 3-RC-1015-NSS-8 2.626 1 .26E-04 Cat. 2 251 64.7 3-RC-1015-NSS-9 2.626 1 .26E-04 Cat. 2 252 63.7 3-RC-1106-BB 1-25 2.626 1.26E-04 Cat. 2 253 63.7 3-RC-1206-BB1-28 2.626 1.26E-04 Cat. 2 254 63.7 3-RC-1306-BB1-28 2.626 1.26E-04 Cat. 2 255 63.8 3-RC-1406-BB1-25 2.626 1.26E-04 Cat. 2 256 57.9 27.5-RC-1103-NSS-3 3.438 1.44E-05 Cat. 3 257 59.7 27.5-RC-1103-NSS-5 3.438 1.44E-05 Cat. 3 258 60.3 27.5-RC-1303-NSS-4 3.438 1.44E-05 Cat. 3 259 59.3 27.5-RC-1403-NSS-3 3.438 1 .44E-05 Cat. 3 260 59.6 27.5-RC-1403-NSS-4 3.438 1.44E-05 Cat. 3 continued next page ...

Saturday 14 th March, 2015, 07:39 39 corresponding: keeejOstpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 261 59.3 31-RC-1302-NSS-7 3.438 1.44E-05 Cat. 3 262 65.9 4-CV-1001-BBI-1 3.438 1.44E-05 Cat. 3 263 66.4 4-CV-1001-BB1-2 3.438 1.44E-05 Cat. 3 264 66.4 4-CV-1118-BB1-1 3.438 1.44E-05 Cat. 3 265 65.6 4-CV-1118-BB1-2 3.438 1.44E-05 Cat. 3 266 64.4 4-CV-1120-BBl-1 3.438 1.44E-05 Cat. 3 267 64.0 4-CV-1120-BB1-2 3.438 1.44E-05 Cat. 3 268 63.1 4-RC-1000-BBI-1 3.438 1.44E-05 Cat. 3 269 63.8 4-RC-1000-BB1-2 3.438 1.44E-05 Cat. 3 270 63.8 4-RC-1000-BB1-3 3.438 1.44E-05 Cat. 3 271 64.2 4-RC-1000-BB1-4 3.438 1.44E-05 Cat. 3 272 64.2 4-RC-1000-BB1-5 3.438 1.44E-05 Cat. 3 273 64.0 4-RC-1000-BB1-6 3.438 1.44E-05 Cat. 3 274 63.9 4-RC-1000-BB1-7 3.438 1.44E-05 Cat. 3 275 62.7 4-RC-1000-BB1-8 3.438 1.44E-05 Cat. 3 276 63.2 4-RC-1003-BBI-1 3.438 1.44E-05 Cat. 3 277 63.3 4-RC-1003-BB1-2 3.438 1.44E-05 Cat. 3 278 63.2 4-RC-1003-BB1-3 3.438 1.44E-05 Cat. 3 279 62.8 4-RC-1003-BB1-4 3.438 1.44E-05 Cat. 3 280 58.4 4-RC-1123-BBl-1 3.438 1.44E-05 Cat. 3 281 64.7 4-RC-1123-BBl-10 3.438 1.44E-05 Cat. 3 282 65.6 4-RC-1123-BB1-11 3.438 1.44E-05 Cat. 3 283 65.9 4-RC-1123-BBl-12 3.438 1.44E-05 Cat. 3 284 65.9 4-RC-1123-BB1-13 3.438 1.44E-05 Cat. 3 285 66.1 4-RC-1123-BB1-14 3.438 1.44E-05 Cat. 3 286 65.9 4-RC-1123-BBl-15 3.438 1.44E-05 Cat. 3 287 63.9 4-RC-1123-BB1-16 3.438 1.44E-05 Cat. 3 288 63.2 4-RC-1123-BB1-17 3.438 1.44E-05 Cat. 3 289 61.8 4-RC-1123-BBl-18 3.438 1.44E-05 Cat. 3 290 61.9 4-RC-1123-BBl-19 3.438 1.44E-05 Cat. 3 291 65.9 4-RC-1123-BB1-2 3.438 1.44E-05 Cat. 3 292 62.8 4-RC-1123-BB1-20 3.438 1.44E-05 Cat. 3 293 65.9 4-RC-1123-BB1-3 3.438 1.44E-05 Cat. 3 294 65.9 4-RC-1123-BB1-4 3.438 1.44E-05 Cat. 3 295 66.0 4-RC-1123-BB1-5 3.438 1.44E-05 Cat. 3 296 66.0 4-RC-1123-BB1-6 3.438 1.44E-05 Cat. 3 297 65.9 4-RC-1123-BB1-7 3.438 1.44E-05 Cat. 3 298 66.0 4-RC-1123-BBl-8 3.438 1.44E-05 Cat. 3 299 64.2 4-RC-1123-BB1-9 3.438 1.44E-05 Cat. 3 300 65.3 4-RC-1126-BB1-1 3.438 1.44E-05 Cat. 3 301 64.3 4-RC-1126-BB1-2 3.438 1.44E-05 Cat. 3 302 64.0 4-RC-1126-BB1-3 3.438 1.44E-05 Cat. 3 303 64.1 4-R.C-1126-BB1-4 3.438 1.44E-05 Cat. 3 304 63.4 4-R.C-1126-BB1-5 3.438 1.44E-05 Cat. 3 305 60.1 4-RC-1126-BB1-6 3.438 1.44E-05 Cat. 3 306 59.5 4-RC-1320-BBl-1 3.438 1.44E-05 Cat. 3 continued next page ...

Saturday 1 4 th March, 2015, 07:39 40 corresponding: keeej k4st pegs. corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 307 65.5 4-RC-1320-BB1-10 3.438 1.44E-05 Cat. 3 308 65.6 4-RC-1320-BBl-11 3.438 1.44E-05 Cat. 3 309 65.6 4-RC-1320-BBl-12 3.438 1.44E-05 Cat. 3 310 60.1 4-RC-1320-BB1-2 3.438 1.44E-05 Cat. 3 311 60.8 4-RC-1320-BB1-3 3.438 1.44E-05 Cat. 3 312 62.9 4-RC-1320-BB1-4 3.438 1.44E-05 Cat. 3 313 63.4 4-RC-1320-BB1-5 3.438 1.44E-05 Cat. 3 314 63.7 4-RC-1320-BB1-6 3.438 1.44E-05 Cat. 3 315 64.0 4-RC-1320-BB1-7 3.438 1.44E-05 Cat. 3 316 64.4 4-RC-1320-BB1-8 3.438 1.44E-05 Cat. 3 317 65.2 4-RC-1320-BB1-9 3.438 1.44E-05 Cat. 3 318 64.9 4-RC-1323-BBl-1 3.438 1.44E-05 Cat. 3 319 65.1 4-RC-1323-BB1-2 3.438 1.44E-05 Cat. 3 320 65.6 4-RC-1323-BB1-3 3.438 1.44E-05 Cat. 3 321 60.7 4-RC-1323-BB1-4 3.438 1.44E-05 Cat. 3 322 60.2 4-RC-1420-BBl-1 3.438 1.44E-05 Cat. 3 323 60.0 4-RC-1422-BBl-1 3.438 1.44E-05 Cat. 3 324 65.9 4-RC-1422-BB1-10 3.438 1.44E-05 Cat. 3 325 65.9 4-RC-1422-BBl-11 3.438 1.44E-05 Cat. 3 326 63.9 4-RC-1422-BBl-12 3.438 1.44E-05 Cat. 3 327 64.7 4-RC-1422-BBl-13 3.438 1.44E-05 Cat. 3 328 64.9 4-RC-1422-BBl-14 3.438 1.44E-05 Cat. 3 329 65.3 4-RC-1422-BB1-15 3.438 1.44E-05 Cat. 3 330 65.9 4-RC-1422-BB1-16 3.438 1.44E-05 Cat. 3 331 66.1 4-RC-1422-BBl-17 3.438 1.44E-05 Cat. 3 332 65.9 4-RC-1422-BB1-18 3.438 1.44E-05 Cat. 3 333 66.1 4-RC-1422-BBl-19 3.438 1.44E-05 Cat. 3 334 60.8 4-RC-1422-BB1-2 3.438 1.44E-05 Cat. 3 335 66.2 4-RC-1422-BB1-20 3.438 1.44E-05 Cat. 3 336 64.4 4-RC-1422-BB1-21 3.438 1.44E-05 Cat. 3 337 63.9 4-RC-1422-BB1-22 3.438 1.44E-05 Cat. 3 338 63.7 4-RC-1422-BB1-23 3.438 1.44E-05 Cat. 3 339 61.5 4-RC-1422-BB1-3 3.438 1.44E-05 Cat. 3 340 61.0 4-RC-1422-BB1-4 3.438 1.44E-05 Cat. 3 341 61.5 4-RC-1422-BB1-5 3.438 1.44E-05 Cat. 3 342 65.7 4-RC-1422-BB1-6 3.438 1.44E-05 Cat. 3 343 65.7 4-RC-1422-BB1-7 3.438 1.44E-05 Cat. 3 344 65.7 4-RC-1422-BB1-8 3.438 1.44E-05 Cat. 3 345 65.7 4-RC-1422-BB1-9 3.438 1.44E-05 Cat. 3 346 53.1 6-RC-1003-BBI-1 5.189 8.12E-06 Cat. 3 347 54.5 6-RC-1003-BBI-10 5.189 8.12E-06 Cat. 3 348 54.3 6-RC-1003-BBI-11 5.189 8.12E-06 Cat. 3 349 51.7 6-RC-1003-BBI-1lA 5.189 8.12E-06 Cat. 3 350 50.1 6-RC-1003-BBR-11B 5.189 8.12E-06 Cat. 3 351 46.7 6-RC-1003-BBI-12 5.189 8.12E-06 Cat. 3 352 42.9 6-RC-1003-BBR-13 5.189 8.12E-06 Cat. 3 continued next page...

Saturday 14 th March, 2015, 07:39 41 corresponding: keeejOctstpegs.coin

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 353 37.8 6-RC-1003-BB1-13A 5.189 8.12E-06 Cat. 3 354 33.7 6-RC-1003-BBI-14 5.189 8.12E-06 Cat. 3 355 53.0 6-RC-1003-BB1-2 5.189 8.12E-06 Cat. 3 356 53.0 6-RC-1003-BB1-3 5.189 8.12E-06 Cat. 3 357 53.3 6-RC-1003-BB1-4 5.189 8.12E-06 Cat. 3 358 53.5 6-RC-1003-BB1-5 5.189 8.12E-06 Cat. 3 359 54.1 6-RC-1003-BB1-6 5.189 8.12E-06 Cat. 3 360 52.4 6-RC-1003-BB1-7 5.189 8.12E-06 Cat. 3 361 48.5 6-RC-1003-BB1-8 5.189 8.12E-06 Cat. 3 362 48.1 6-RC-1003-BB1-9 5.189 8.12E-06 Cat. 3 363 48.0 6-RC-1003-BB1-9A 5.189 8.12E-06 Cat. 3 364 48.0 6-RC-1003-BB1-9B 5.189 8.12E-06 Cat. 3 365 33.8 6-RC- 1003-BB 1-PRZ- 1-N2-SE 5.189 8.12E-06 Cat. 3 366 40.7 6-RC-1004-NSS-1 5.189 8.12E-06 Cat. 3 367 42.6 6-RC-1004-NSS-2 5.189 8.12E-06 Cat. 3 368 46.2 6-RC-1004-NSS-3 5.189 8.12E-06 Cat. 3 369 41.4 6-RC-1004-NSS-4 5.189 8.12E-06 Cat. 3 370 40.2 6-RC- 1004-NSS-5 5.189 8.12E-06 Cat. 3 371 47.0 6-RC- 1004-NSS-6 5.189 8.12E-06 Cat. 3 372 49.4 6-RC-1004-NSS-7 5.189 8.12E-06 Cat. 3 373 40.7 6-RC-1004-NSS-PRZ- 1-N3-SE 5.189 8.12E-06 Cat. 3 374 38.5 6-RC-1009-NSS-1 5.189 8.12E-06 Cat. 3 375 40.2 6-RC-1009-NSS-2 5.189 8.12E-06 Cat. 3 376 44.8 6-RC- 1009-NSS-3 5.189 8.12E-06 Cat. 3 377 40.9 6-RC-1009-NSS-4 5.189 8.12E-06 Cat. 3 378 37.8 6-RC-1009-NSS-5 5.189 8.12E-06 Cat. 3 379 36.7 6-RC-1009-NSS-6 5.189 8.12E-06 Cat. 3 380 38.3 6-RC-1009-NSS-7 5.189 8.12E-06 Cat. 3 381 41.4 6-RC- 1009-NSS-8 5.189 8.12E-06 Cat. 3 382 44.1 6-RC-1009-NSS-9 5.189 8.12E-06 Cat. 3 383 38.7 6-RC-1009-NSS-P RZ- 1-N4C-SE 5.189 8.12E-06 Cat. 3 384 35.6 6-RC-1012-NSS-1 5.189 8.12E-06 Cat. 3 385 43.2 6-RC-1012-NSS-10 5.189 8.12E-06 Cat. 3 386 43.7 6-RC-1012-NSS-11 5.189 8.12E-06 Cat. 3 387 37.1 6-RC-1012-NSS-2 5.189 8.12E-06 Cat. 3 388 38.1 6-RC-1012-NSS-3 5.189 8.12E-06 Cat. 3 389 38.4 6-RC-1012-NSS-4 5.189 8.12E-06 Cat. 3 390 41.0 6-RC-1012-NSS-5 5.189 8.12E-06 Cat. 3 391 41.8 6-RC-1012-NSS-6 5.189 8.12E-06 Cat. 3 392 43.1 6-RC-1012-NSS-7 5.189 8.12E-06 Cat. 3 393 42.6 6-RC-1012-NSS-8 5.189 8.12E-06 Cat. 3 394 39.9 6-RC-1012-NSS-9 5.189 8.12E-06 Cat. 3 395 35.5 6-RC-1012-NSS-PRZ-1-N4B-SE 5.189 8.12E-06 Cat. 3 396 36.2 6-RC-1015-NSS-1 5.189 8.12E-06 Cat. 3 397 43.8 6-RC-1015-NSS-10 5.189 8.12E-06 Cat. 3 398 54.8 6-RC-1015-NSS-11 5.189 8.12E-06 Cat. 3 continued next page ...

Saturday 14 th March, 2015, 07:39 42 corresponding: keeej@)stpegs.coni

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 399 56.7 6-RC-1015-NSS-12 5.189 8.12E-06 Cat. 3 400 56.9 6-RC-1015-NSS-13 5.189 8.12E-06 Cat. 3 401 56.0 6-RC-1015-NSS-14 5.189 8.12E-06 Cat. 3 402 56.0 6-RC-1015-NSS-15 5.189 8.12E-06 Cat. 3 403 38.1 6-RC-1015-NSS-2 5.189 8.12E-06 Cat. 3 404 39.4 6-RC-1015-NSS-3 5.189 8.12E-06 Cat. 3 405 38.3 6-RC-1015-NSS-4 5.189 8.12E-06 Cat. 3 406 36.2 6-RC-1015-NSS-5 5.189 8.12E-06 Cat. 3 407 35.4 6-RC-1015-NSS-6 5.189 8.12E-06 Cat. 3 408 35.3 6-RC-1015-NSS-7 5.189 8.12E-06 Cat. 3 409 38.3 6-RC-1015-NSS-8 5.189 8.12E-06 Cat. 3 410 40.7 6-RC-1015-NSS-9 5.189 8.12E-06 Cat. 3 411 66.8 6-SI-1108-BBl-1 5.189 8.12E-06 Cat. 3 412 66.7 6-SI-1108-BB1-2 5.189 8.12E-06 Cat. 3 413 66.1 6-SI-1108-BB1-3 5.189 8.12E-06 Cat. 3 414 58.7 6-SI-1108-BB1-4 5.189 8.12E-06 Cat. 3 415 64.0 6-SI-1111-BBI-1 5.189 8.12E-06 Cat. 3 416 63.9 6-SI-1111-BB1-2 5.189 8.12E-06 Cat. 3 417 66.9 6-SI-1208-BB1-i 5.189 8.12E-06 Cat. 3 418 66.8 6-SI-1208-BBI-2 5.189 8.12E-06 Cat. 3 419 66.1 6-SI-1208-BB1-3 5.189 8.12E-06 Cat. 3 420 59.8 6-SI-1208-BBI-4 5.189 8.12E-06 Cat. 3 421 64.7 6-SI-1211-BBI-I 5.189 8.12E-06 Cat. 3 422 64.5 6-SI-1211-BB1-2 5.189 8.12E-06 Cat. 3 423 63.8 6-SI-1308-BBI-1 5.189 8.12E-06 Cat. 3 424 65.0 6-SI-1308-BB1-2 5.189 8.12E-06 Cat. 3 425 65.3 6-SI-1308-BB1-3 5.189 8.12E-06 Cat. 3 426 64.2 6-SI-1308-BB1-4 5.189 8.12E-06 Cat. 3 427 53.1 6-SI-1327-BB1-1 5.189 8.12E-06 Cat. 3 428 53.6 6-SI-1327-BB1-2 5.189 8.12E-06 Cat. 3 429 54.1 6-SI-1327-BB1-3 5.189 8.12E-06 Cat. 3 430 53.6 6-SI-1327-BB1-4 5.189 8.12E-06 Cat. 3 431 54.5 6-SI-1327-BB1-5 5.189 8.12E-06 Cat. 3 432 55.3 6-SI-1327-BB1-6 5.189 8.12E-06 Cat. 3 433 56.3 6-SI-1327-BB1-7 5.189 8.12E-06 Cat. 3 434 35.9 29-RC-1101-NSS-2 6.813 2.27E-06 Cat. 3 435 36.0 29-RC- 1201-NSS-2 6.813 2.27E-06 Cat. 3 436 35.5 29-RC-1301-NSS-2 6.813 2.27E-06 Cat. 3 437 46.2 8-RC-1114-BB1-1 6.813 2.27E-06 Cat. 3 438 47.8 8-RC-1114-BB1-2 6.813 2.27E-06 Cat. 3 439 46.2 8-RC-1114-BB1-3 6.813 2.27E-06 Cat. 3 440 43.3 8-R.C-1114-BB1-4 6.813 2.27E-06 Cat. 3 441 39.6 8-RC-1114-BB1-5 6.813 2.27E-06 Cat. 3 442 36.3 8-RC-1114-BB1-6 6.813 2.27E-06 Cat. 3 443 46.5 8-RC-1214-BBI-1 6.813 2.27E-06 Cat. 3 444 48.0 8-RC-1214-BB1-2 6.813 2.27E-06 Cat. 3 continued next page ...

Saturday 1 4 th March, 2015, 07:39 43 corresponding: keeejcgstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 445 46.7 8-RC-1214-BB1-3 6.813 2.27E-06 Cat. 3 446 43.7 8-RC-1214-BB1-4 6.813 2.27E-06 Cat. 3 447 40.1 8-RC-1214-BB1-5 6.813 2.27E-06 Cat. 3 448 37.1 8-RC-1214-BBi-6 6.813 2.27E-06 Cat. 3 449 45.0 8-RC-1324-BB1-1 6.813 2.27E-06 Cat. 3 450 46.6 8-RC-1324-BB1-2 6.813 2.27E-06 Cat. 3 451 45.6 8-RC-1324-BB1-3 6.813 2.27E-06 Cat. 3 452 44.5 8-RC-1324-BB1-4 6.813 2.27E-06 Cat. 3 453 40.3 8-RC-1324-BB1-5 6.813 2.27E-06 Cat. 3 454 37.0 8-RC-1324-BB1-6 6.813 2.27E-06 Cat. 3 455 63.2 8-RH-1108-BB1-1 6.813 2.27E-06 Cat. 3 456 62.9 8-RH-1108-BBi-2 6.813 2.27E-06 Cat. 3 457 45.8 8-R.H-1112-BB1-1 6.813 2.27E-06 Cat. 3 458 47.3 8-RH-1112-BBI-lA 6.813 2.27E-06 Cat. 3 459 46.9 8-RH-1112-BB1-2 6.813 2.27E-06 Cat. 3 460 64.2 8-RH-1208-BBI-1 6.813 2.27E-06 Cat. 3 461 63.9 8-RH-1208-BB1-2 6.813 2.27E-06 Cat. 3 462 45.1 8-RH-1212-BBI-1 6.813 2.27E-06 Cat. 3 463 48.1 8-RH-1212-BB1-2 6.813 2.27E-06 Cat. 3 464 57.2 8-RH-1308-BB1-1 6.813 2.27E-06 Cat. 3 465 58.9 8-RH-1308-BB1-2 6.813 2.27E-06 Cat. 3 466 46.9 8-RH-1315-BBl-1 6.813 2.27E-06 Cat. 3 467 52.1 8-SI-1108-BB1-I 6.813 2.27E-06 Cat. 3 468 48.8 8-SI-1108-BB1-2 6.813 2.27E-06 Cat. 3 469 45.1 8-SI-1108-BB1-3 6.813 2.27E-06 Cat. 3 470 41.2 8-SI-1108-BB1-4 6.813 2.27E-06 Cat. 3 471 43.9 8-SI-1108-BB1-5 6.813 2.27E-06 Cat. 3 472 52.4 8-SI-1208-BB1-1 6.813 2.27E-06 Cat. 3 473 50.5 8-SI-1208-BB1-2 6.813 2.27E-06 Cat. 3 474 45.9 8-SI-1208-BB1-3 6.813 2.27E-06 Cat. 3 475 41.9 8-SI-1208-BB1-3A 6.813 2.27E-06 Cat. 3 476 45.0 8-SI-1208-BB1-4 6.813 2.27E-06 Cat. 3 477 48.2 8-SI-1327-BB1-1 6.813 2.27E-06 Cat. 3 478 35.4 8-SI-1327-BB1-10 6.813 2.27E-06 Cat. 3 479 41.1 8-SI-1327-BB1-11 6.813 2.27E-06 Cat. 3 480 48.8 8-SI-1327-BB1-2 6.813 2.27E-06 Cat. 3 481 49.2 8-SI-1327-BB1-3 6.813 2.27E-06 Cat. 3 482 49.9 8-SI-1327-BB1-4 6.813 2.27E-06 Cat. 3 483 51.6 8-SI-1327-BB1-5 6.813 2.27E-06 Cat. 3 484 49.7 8-SI-1327-BB1-6 6.813 2.277E-06 Cat. 3 485 45.1 8-SI-1327-BB1-7 6.813 2.27E-06 Cat. 3 486 40.3 8-SI-1327-BB1-8 6.813 2.27E-06 Cat. 3 487 39.0 8-SI-1327-BB1-9 6.813 2.27E-06 Cat. 3 488 61.4 10-RH-1108-BBI-1 8.5- 1.30E-06 Cat. 4 489 49.7 10-RH-i 108-BBI-10 8.5 1.30E-06 Cat. 4 490 61.1 10-RH-1108-BBI-IA 8.5 1.30E-06 Cat. 4 continued next page ...

Saturday 1 4 th March, 2015, 07:39 44 corresponding: keeej Oustpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (Ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 491 61.0 10-RH-1108-BB1-2 8.5 1.30E-06 Cat. 4 492 60.9 10-RH-1108-BBI-3 8&5 1.30E-06 Cat. 4 493 60.7 10-RH-1108-BB1-4 8.5 1.30E-06 Cat. 4 494 60.7 10-RH-1108-BB1-5 8.5 1.30E-06 Cat. 4 495 60.8 10-RH-1108-BBI-6 8.5 1.30E-06 Cat, 4 496 60.2 10-RH-1108-BB1-7 8.5 1.30E-06 Cat. 4 497 49.0 10-RH-1108-BB1-8 8.5 1.30E-06 Cat. 4 498 49.2 10-RH-1108-BB1-9 8.5 1.30E-06 Cat. 4 499 62.6 10-RH-1208-BBI-1 8.5 1.30E-06 Cat. 4 500 51.1 10-RH-1208-BBI-10 8.5 1.30E-06 Cat. 4 501 52.0 10-RH-1208-BB1-11 8.5 1.30E-06 Cat. 4 502 62.3 10-RH-1208-BB1-2 8.5 1.30E-06 Cat. 4 503 62.2 10-RH-1208-BB1-3 8.5 1.30E-06 Cat. 4 504 61.6 10-RH-1208-BB1-4 8.5 1.30E-06 Cat. 4 505 61.3 10-RH-1208-BB1-5 8.5 1.30E-06 Cat. 4 506 61.4 10-RH-1208-BB1-6 8.5 1.30E-06 Cat. 4 507 60.6 10-RH-1208-BB1-7 8.5 1.30E-06 Cat. 4 508 50.9 10-RH-1208-BB1-8 8.5 1.30E-06 Cat. 4 509 50.6 10-RH-1208-BB1-9 8.5 1.30E-06 Cat. 4 510 57.0 10-RH-1308-BBI-1 8.5 1.30E-06 Cat. 4 511 62.5 10-RH-1308-BB1-2 8.5 1.30E-06 Cat. 4 512 62.6 10-RH-1308-BB1-3 8.5 1.30E-06 Cat. 4 513 62.5 10-RH-1308-BB1-4 8.5 1.30E-06 Cat. 4 514 62.8 10-RH-1308-BB1-5 8.5 1.30E-06 Cat. 4 515 61.9 10-RH-1308-BB1-6 8.5 1.30E-06 Cat. 4 516 61.8 10-RH-1308-BB1-7 8.5 1.30E-06 Cat. 4 517 61.4 10-RH-1308-BB1-8 8.5 1.30E-06 Cat. 4 518 30.4 12-RC-1112-BBI-10 10.126 9.75E-07 Cat. 4 519 30.3 12-RC-1112-BBI-11 10.126 9.75E-07 Cat. 4 520 9.6 12-RC-1112-BB1-2 10.126 9.75E-07 Cat. 4 521 16.1 12-RC-1112-BB1-3 10.126 9.75E-07 Cat. 4 522 20.2 12-RC-1112-BB1-4 10.126 9.75E-07 Cat. 4 523 22.3 12-RC-1112-BB1-5 10.126 9.75E-07 Cat. 4 524 18.9 12-RC-1112-BB1-6 10.126 9.75E-07 Cat. 4 525 16.6 12-RC-1112-BB1-7 10.126 9.75E-07 Cat. 4 526 17.6 12-RC-1112-BB1-8 10.126 9.75E-07 Cat. 4 527 27.4 12-RC-1112-BB1-9 10.126 9.75E-07 Cat. 4 528 47.4 12-RC-1125-BBl-1 10.126 9.75E-07 Cat. 4 529 48.7 12-RC-1125-BB1-2 10.126 9.75E-07 Cat. 4 530 48.9 12-RC-1125-BB1-3 10.126 9.75E-07 Cat. 4 531 49.2 12-RC-1125-BB1-4 10.126 9.75E-07 Cat. 4 532 49.2 12-RC-1125-BB1-5 10.126 9.75E-07 Cat. 4 533 46.5 12-RC-1125-BB1-6 10.126 9.75E-07 Cat. 4 534 44.9 12-RC-1125-BB1-7 10.126 9.75E-07 Cat. 4 535 4.4 12-RC-1212-BBI-1 10.126 9.75E-07 Cat. 4 536 12.7 12-RC-1212-BB1-2 10.126 9.75E-07 Cat. 4 continued next page ...

Saturday 14 th March, 2015, 07:39 45 corresponding: keeejOclstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 537 17.0 12-RC-1212-BB1-3 10.126 9.75E-07 Cat. 4 538 22.7 12-RC-1212-BB1-4 10.126 9.75E-07 Cat. 4 539 24.1 12-RC-1212-BB1-5 10.126 9.75E-07 Cat. 4 540 19.6 12-RC-1212-BB1-6 10.126 9.75E-07 Cat. 4 541 17.7 12-RC-1212-BB1-7 10.126 9.75E-07 Cat. 4 542 11.9 12-RC-1212-BB1-8 10.126 9.75E-07 Cat. 4 543 50.5 12-RC-1221-BBl-1 10.126 9.75E-07 Cat. 4 544 51.4 12-RC-1221-BB1-2 10.126 9.75E-07 Cat. 4 545 51.0 12-RC-1221-BB1-3 10.126 9.75E-07 Cat. 4 546 49.9 12-RC-1221-BB1-4 10.126 9.75E-07 Cat. 4 547 48.4 12-RC-1221-BB1-5 10.126 9.75E-07 Cat. 4 548 46.4 12-RC-1221-BB1-6 10.126 9.75E-07 Cat. 4 549 45.1 12-RC-1221-BB1-7 10.126 9.75E-07 Cat. 4 550 4.6 12-RC-1221-BB1-8 10.126 9.75E-07 Cat. 4 551 4.0 12-RC-1312-BBI-1 10.126 9.75E-07 Cat. 4 552 23.4 12-RC-1312-BBI-10 10.126 9.75E-07 Cat. 4 553 24.1 12-RC-1312-BBI-i1 10.126 9.75E-07 Cat. 4 554 12.2 12-RC-1312-BB1-2 10.126 9.75E-07 Cat. 4 555 16.6 12-RC-1312-BB1-3 10.126 9.75E-07 Cat. 4 556 22.2 12-RC-1312-BB1-4 10.126 9.75E-07 Cat. 4 557 23.7 12-RC-1312-BB1-5 10.126 9.75E-07 Cat. 4 558 19.1 12-RC-1312-BB1-6 10.126 9.75E-07 Cat. 4 559 17.5 12-RC-1312-BB1-7 10.126 9.75E-07 Cat. 4 560 7.5 12-RC-1312-BBI-8 10.126 9.75E-07 Cat. 4 561 21.6 12-RC-1312-BB1-9 10.126 9.75E-07 Cat. 4 562 29.5 12-RH-1101-BBI-1 10.126 9.75E-07 Cat. 4 563 51.4 12-RH-1101-BBI-10 10.126 9.75E-07 Cat. 4 564 52.5 12-RH-1101-BBI-11 10.126 9.75E-07 Cat. 4 565 56.7 12-RH-1101-BBI-12 10.126 9.75E-07 Cat. 4 566 52.9 12-RH-1101-BBI-13 10.126 9.75E-07 Cat. 4 567 55.8 12-RH-1101-BBI-14 10.126 9.75E-07 Cat. 4 568 56.0 12-RH-1101-BBl-15 10.126 9.75E-07 Cat. 4 569 55.0 12-RH-1101-BB1-16 10.126 9.75E-07 Cat. 4 570 32.8 12-RH-1101-BB1-2 10.126 9.75E-07 Cat. 4 571 31.6 12-RH-1101-BB1-3 10.126 9.715E-07 Cat. 4 572 13.6 12-RH-1101-BB1-3A 10.126 9.75E-07 Cat. 4 573 16.4 12-RH-1101-BB1-4 10.126 9.75E-07 Cat. 4 574 25.3 12-RH-1101-BB1-5 10.126 9.75E-07 Cat. 4 575 26.1 12-RH-1101-BB1-6 10.126 9.75E-07 Cat. 4 576 25.7 12-RH-1101-BB1-7 10.126 9.75E-07 Cat. 4 577 32.0 12-RH-1101-BB1-8 10.126 9.75E-07 Cat. 4 578 52.8 12-RH-1101-BB1-9 10.126 9.75E-07 Cat. 4 579 17.9 12-RH-1201-BB1-1 10.126 9.75E-07 Cat. 4 580 28.1 12-RH-1201-BB1 -10 10.126 9.75E-07 Cat. 4 581 50.0 12-RH-1201-BB1-11 10.126 9.75E-07 Cat. 4 582 51.8 12-RH-1201-BB1-12 10.126 9.75E-07 Cat. 4 continued next page ...

Saturday 14 th March, 2015, 07:39 46 corresponding: keeej(O-stpegs.coni

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

... continued No. Margin (ibm) Location DEGB fi NUREG 1829 Cat.

Size (in) 583 52.2 12-RH-1201-BBI-13 10.126 9.75E-07 Cat. 4 584 55.2 12-RH-1201-BB1-14 10.126 9.75E-07 Cat. 4 585 57.8 12-R.H-1201-BBI-15 10.126 9.75E-07 Cat. 4 586 57.5 12-RH-1201-BBI-16 10.126 9.75E-07 Cat. 4 587 56.9 12-RH-1201-BBI-17 10.126 9.75E-07 Cat. 4 588 22.8 12-RH-1201-BB1-2 10.126 9.75E-07 Cat. 4 589 26.6 12-RH-1201-BBI-3 10.126 9.75E-07 Cat. 4 590 27.2 12-RH-1201-BB1-4 10.126 9.75E-07 Cat. 4 591 26.7 12-RH-1201-BB1-5 10.126 9.75E-07 Cat. 4 592 12.4 12-RH-1201-BB1-6 10.126 9.75E-07 Cat. 4 593 21.9 12-RH-1201-BB1-7 10.126 9.75E-07 Cat. 4 594 22.6 12-RH-1201-BB1-8 10.126 9.75E-07 Cat. 4 595 21.5 12-RH-1201-BB1-9 10.126 9.75E-07 Cat. 4 596 27.4 12-RH-1301-BBI-1 10.126 9.75E-07 Cat. 4 597 54.9 12-RH-1301-BBI-10 10.126 9.75E-07 Cat. 4 598 29.8 12-RH-1301-BB1-2 10.126 9.75E-07 Cat. 4 599 29.9 12-RH-1301-BB1-3 10.126 9.75E-07 Cat. 4 600 27.6 12-RH-1301-BB1-4 10.126 9.75E-07 Cat. 4 601 31.5 12-RH-1301-BB1-5 10.126 9.75E-07 Cat. 4 602 53.2 12-RH-1301-BB1-5A 10.126 9.75E-07 Cat. 4 603 52.9 12-RH-1301-BB1-6 10.126 9.75E-07 Cat. 4 604 53.0 12-RH-1301-BBI-7 10.126 9.75E-07 Cat. 4 605 54.5 12-RH-1301-BB1-8 10.126 9.75E-07 Cat. 4 606 55.0 12-RH-1301-BB1-9 10.126 9.75E-07 Cat. 4 607 50.9 12-SI-1125-BB1-1 10.126 9.75E-07 Cat. 4 608 48.6 12-SI-1125-BB1-2 10.126 9.75E-07 Cat. 4 609 48.1 12-SI-1125-BB1-3 10.126 9.75E-07 Cat. 4 610 48.0 12-SI-1125-BB1-4 10.126 9.75E-07 Cat. 4 611 53.5 12-SI-1218-BB1-1 10.126 9.75E-07 Cat. 4 612 51.3 12-SI-1218-BB1-2 10.126 9.75E-07 Cat. 4 613 50.7 12-SI-1218-BB1-3 10.126 9.75E-07 Cat. 4 614 50.5 .12-SI-1218-BB1-4 10.126 9.75E-07 Cat. 4 615 60.4 12-SI-1315-BB1-1 10.126 9.75E-07 Cat. 4 616 59.9 12-SI-1315-BB1-2 10.126 9.75E-07 Cat. 4 617 59.3 12-SI-1315-BB1-3 10.126 9.75E-07 Cat. 4 618 59.4 12-SI-1315-BB1-4 10.126 9.75E-07 Cat. 4 619 59.6 12-SI-1315-BB1-5 10.126 9.75E-07 Cat. 4 620 21.9 12-SI-1315-BB1-6 10.126 9.75E-07 Cat. 4 621 20.3 27.5-RC-1103-NSS-4 10.126 9.75E-07 Cat. 4 622 9.6 27.5-RC-1203-NSS-3 10.126 9.75E-07 Cat. 4 623 8.7 27.5-RC-1303-NSS-3 10.126 9.75E-07 Cat. 4 624 0.5 29-RC-1301-NSS-3 10.126 9.75E-07 Cat. 4 625 1.5 16-RC-1412-NSS-1 12.814 4.37E-07 Cat. 4 626 52.1 16-RC-1412-NSS-3 12.814 4.37E-07 Cat. 4 627 55.0 16-RC-1412-NSS-4 12.814 4.37E-07 Cat. 4 628 0.6 16-RC-1412-NSS-PRZ-1-N1-SE 12.814 4.37E-07 Cat. 4 Saturday 14"' March, 2015, 07:39 47 corresponding: keeej (Q-tist pegs. coni

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Acknowledgements and primary contributions Work presented in this article was developed by YK.risk, LLC funded by STPNOC contract B05657, Revision 0 and Revision 1, and by Alion Science and Technology through con-tract B04461, Revision 5. Reduction of CASA Grande results was performed by Jeremy Tejada under the direction of John Hasenbein and funded by STPNOC grant B04425.

Development of the strainer mass conservation equations was supported by Alex Zolan under the direction of John Hasenbein and funded by STPNOC grant B04425, Revision 4.

Seyed Reihani contributed to developing the mass conservation equations at UIUC under STPNOC grant B05270, Revision 3. The top down frequency methodology was originally developed by Elmira Popova at UT Austin, funded by STPNOC grant B04425, Revision

0. Further development for implementation ROVERD was supported by David Johnson and Don Wakefield at ABS Consulting under STPNOC contract B05760, Revision 1 and Bruce Letellier at Alionscience and Technology under STPNOC contract B04461, Revision

6. Work contributed by Ernie Kee is funded by STPNOC under YK.risk, LLC contract B05657, Revision 1.

Saturday 1 4 th March, 2015, 07:39 48 corresponding: keeej(Qstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages References AREVA (2008, August). South Texas Project Test Report for ECCS Strainer Testing.

AREVA NP Document 66-9088089-000, AREVA NP, 7207 IBM Drive, Charlotte, NC 28262.

Letellier, B., T. Sande, and G. Zigler (2013, November). South Texas Project Risk-Informed GSI-191 Evaluation, Volume 3, CASA Grande Analysis. Technical report, STP-RIGSI191-V03, Revision 2, Alion Science and Technology.

NEI (2004, May). Pressurized Water Reactor Sump Performance Evaluation Methodology.

Technical Report 04-07, Nuclear Energy Institute, 1776 I Street, Washington, DC.

NRC (2011). Regulatory Guide 1.174: An Approach for Using Probabilistic Risk As-sessment In Risk-Informed Decisions On Plant-Specific Changes to the Licensing Basis, Revision 2, Nuclear Regulatory Commission, Washington, DC.

Ogden, N., D. Morton, and .1. Tejada (2013, June). South Texas Project Risk-Informed GSI-191 Evaluation: Filtration as a Function of Debris Mass on the Strainer: Fitting a Parametric Physics-Based Model. Technical report, STP-RIGSI191-V03.06, The Uni-versity of Texas at Austin, Austin, TX.

PWROG (2011, October). Evaluation of Long - Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid. WCAP 16793, Pressurized Water Reactor Owners Group, Pittsburgh, PA.

Tregoning, R., L. Abramson, and P. Scott (2008, April). Estimating Loss-of-Coolant Acci-dent (LOCA) Frequencies Through the Elicitation Process. NUREG/CR 1829, Nuclear Regulatory Commission, Washngton, DC.

Vaghetto, R. and Y. A. Hassan (2013). Study of debris-generated core blockage scenar-ios during loss of coolant accidents using RELAP5-3D. Nuclear Engineer-ing and De-sign 261 (0), 144 - 155.

9 Acronyms CASA Grande Containment Accident Stochastic Analysis (CASA) Grande CDF Core Damage Frequency ACDF Change in core damage frequency above a baseline level ALERF Change in large early release frequency above a baseline level CLB Cold Leg Break Saturday 1 4 th March, 2015, 07:39 49 corresponding: keeej ýQ)st pegs. corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages CSS Containment Spray System DEGB Double-Ended Guillotine Break ECCS Emergency Core Cooling System FA Fuel Assembly. Several fuel assemblies are loaded in the reactor vessel to form the reactor core GSI-191 Generic Safety Issue 191 - the NRC Generic Safety Issue number 191 HLB Hot Leg Break HISO Hot Leg Switch Over LDFG Low Density Fiberglass (such as NUKONTM)

LERF Large Early Release Frequency LOCA Loss of Coolant Accident MLOCA Medium Break Loss of Coolant Accident PCT Peak Cladding Temperature PRA Probabilistic Risk Assessment PWROG Pressurized Water Reactor Owners Group RCB Reactor Containment Building RCFC The Reactor Containment Fan Coolers RCS Reactor Coolant System ROVERD Risk-informed Over Deterministic SLOCA Small Break Loss of Coolant Accident STP South Texas Project ZOI Zone of Influence Di The break size at any particular location (locations indexed by i = 1,2,... N)

D""all corresponds to the smallest break size at any particular location that produces more fines in the ECCS sump than the tested amount 50 corresponding: keeej@stpegs.com 1 4 th Saturday 14 Saturday 1h March, 2015, 07:39 March, 2015, 07:39 50 corresponding: keeejOstpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 10 LDFG mass conservation solution implementation The following listings are Python source code and the inputs used to generate the results in Section 3.2. Five input files are required for the analysis performed summarized in Table 2.

The input files are in the ".CSV" text format (comma separated variables) and can be imported into (for example) the Microsoft application, EXCEL for ease of editing.

The Python source code is in Listing 1. The following lists the inputs used in the mass conservation study summarized in Section 3.2:

1. The time-dependent flow inputs are listed in Listing 2.

2. Constants for high pool concentration, high filtration efficiency are listed in Listing 3.

3. Constants for high pool concentration, low filtration efficiency are listed in Listing 4.

4. Constants for low pool concentration, low filtration efficiency are listed in Listing 5.

5. Constants for low pool concentration, high filtration efficiency are listed in Listing 6.

Saturday 1 4 th March, 2015, 07:39 51 corresponding: keeej(D-stpegs.corn

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Listing 1: Source listing for (1c) solution, Alex Zolan, UT Austin, 02 March, 2015

%\multicolumns{1}

Recirculation / Core Debris Tracking Tool System of Differential Equations Solver Alex Zolan Updated March 2, 2015 The purpose of the program is to simulate debris moving through a recirculating pool from which strainers can filter out some debris, and some of the debris that passes through the strainers may attach itself to the core.

import time import scipy import scipy.integrate import matplotlib matplotlib. use 'Agg')

import matplotlib.pyplot as pit import pandas import csv class MassCalculator(object):

".""Notethat in initialization, we allow for inputs to be left out of the input file and still allow the program to run using default values in their place. When a default value is used, a note is printed to the console to inform the user.' ..

def ____init (self, params):

1. pool volume (gallons) and initial mass in pool (grams) if "M-pO" in params.keysO: self.M-pO = params["MpO"]

else:

self.Mp 0 = 3000.0 print "M_p0Ounotuinuinputs.uuDefaultuvalueuofu3OOOuused."

if "V-p" in params.keysO: self.V-p = params["Vp"]

else:

self.Vp = 50000.0 print "V punotuinuinputs.juDefaultjvalueuof 5OOO0uused."

1. Initial mass on strainers Saturday 1 4 th March, 2015, 07:39 52 corresponding: keeej 3cstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages if "M s a 0" in params.keysO: self.Ms a.0 = params["Msa_0"]

else:

self.Msa_0 = 0.0 print "M_s_a_Ojnotuinuinputs.uuDefaultuvalueuofuOuused."

if "Msb-0" in params.keysO: self.Msb0--= params["Msb__0"]

else:

self.M s b_0 = 0.0 print "M s_b_Ounotuinuinputs.uuDefaultuvalueuofuOuused."

if "MscO" in params.keysO: self.Ms c.0 = params["Msc_.0"]

else:

self.Msc0-- = 0.0 print "MscOunotuinuinputs.uuDefaultuvalueuofuOuused."

1. initial mass on core if "Mc_0" in params.keysO: self.Mc0--= params["Mc_0"]

else:

self.M c0- = 0.0 print "M cOunotuinuinputs.uuDefaultuvalueuofuO.O.used."

1. gamma, the percentage of water flowing back to the strainers if "gamma~a" in params.keysO: self.gamma a = params["gamma a"]

else:

self.gamma_a = 0.0 print "gamma-aunotuinuinputs.uuDefaultuvalueuofuO.Ouused."

if "gamma b" in params.keysO: self.gamma b -=params["gammab"I else:

self.gammab = 0.0 print "gamma.bunotuinuinputs.uuDefault0valueuofjO.Ouused."

if "gamma-c" in params.keysO: self.gamma c= c params["gammac"]

else:

self.gammac = 0.0 print "gamma-cunotuinuinputs.juDefaultuvalueuofuO.Ouused."

1. strainer flow rates in gallons per minute (gpm) if "Q. s a" in params.keysO: self.Q-s-a = params["Q-s-a"]

else:

self.Q s_a = 1000.0 print "Q s_aunot jinuinputs. uuDefaultuvalueofu 1000. Ouused."

if "Q. s b" in params.keysO: self.Q s-b = params["Q-s-b"]

else:

self.Q sb = 1000.0 print "Q s_bunotuinuinputs. uuDefaultjvalueuofj 1000. Ouused."

Saturday 1 4 th March, 2015, 07:39 53 corresponding: keeejL1)stpegs.coni

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages if "Q.-s-c" in params.keysO: self.Q_s_c = pararns["Q-s-c"]

else:

self.Q sc = 1000.0 print "Q s cjnot uinuinputs .uuDefaultjvalueuofu 1000. 0used."

1. core flow rate in gpm if "Q-c" in params.keyso: self.Q c = params["Q c"]

else:

self.Q_c = 1600.0 print "Q1cunotuinuinputs.ujDefaultuvalueuof1600.0uused."

1. flltration rate (function of mass) if "in" in params.keysO: self.m = params["m"I else:

self.rn = 0.0003391 -#lowerenvelope print "rnu(filtrationufunction) unotuinuinputs . juDefaultuofuO.000339 1u used."

if "b" in params.keysO: self.b = params["b"I else:

self.b = 0.6560 #lower envelope print "bj(filtrationufunction)unotuinuinputs.uuDefaultuofuO.6560uused."

if "M c" in params.keysO: self.threshold = params["Mc"i else:

self.threshold = 880 *lower envelope print "M c,(filtrationufunction)unotuinuinputs. uuDefaultuofu880uused."

if "delta" in params.keysO: self.delta = params["delta"]

else:

self.delta = 0.0013 1lower envelope print "deltaj(filtrationufunction)unotuinuinputs.uuDefaultuofu0.001 3 u used."

if "a" in params.keysO: self.a = params["a"I else:

self.a = 1.0 #lower envelope

1. this upper bound is not expected to be used in most cases, so it is not

1. called out in the console.,

-#print"a (filtration function) not in inputs. Default of 1.0 used."

def get FlowRat eStrainerA(self,t):

"" "returnsthe flow rate out of strainerA, in gallons per minute.

This function is assumed to be known with respect to time, but currently has only a constant...",

Saturday 14 th March, 2015, 07:39 54 corresponding: keeejQ-(stpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages if type(self.Q s-a) == float: return self.Qts a else:

1. if not a constant, use the flow rate just before the time

1. period that exceeds the input t. otherwise, use the

1. last flow rate given if self.Q__ sa["t"][0] > t: return 0 for i in range(1,len(self.Q sa[t"t])):

if self.Q s a["t"][i] > t:

return self. Qsa["vals"J [i-1]

return self.Q s a["vals"] [-1]

def get FlowRat eStrainerB (self, t):

.... returns the flow rate out of strainer B, in gallons per minute.

This function is assumed to be known with respect to time, but currently has only a constant."....

if type(self.Q s b) == float: return self.Q s b #if the input is a constant, just report that.

else:

1. if not a constant, use the flow rate just before the time

1. period that exceeds the input t. otherwise, use the

1. last flow rate given if self.Qsb["t"][0] > t: return 0 for i in range(1,len(self.Q s__b[t"])):

if self.Qs-b['t'][i] > t:

return self. Qsb["vals" [i-11]

return self.Q s b["vals"][-1]

def get FlowRat eStrainerC(self, t):

"""returns the flow rate out of strainer C, in gallons per minute.

This function is assumed to be known with respect to time, but currently has only a constant. "....

if type(self.Q__sc) == float: return self.Q.s-c else:

1. if not a constant, use the flow rate just before the time

1. period that exceeds the input t. otherwise, use the

1. • lastflow rate given if self.Q s c["t"][0] > t: return 0 for i in range(1,len(self.Q s__c(t"])):

if self.Q s c["t"][i] > t:

return self.Q s c["vals"][i-1]

return self.Q s c["vals"] [-1]

Saturday 1 4 th March, 2015, 07:39 55 corresponding: keeejQtstpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages def getFlowRateCore(self, t):

.. returns the flow rate through the core, in gallons per minute.

This function is assumed to be known with respect to time.

if type(self.Q c) == float: return self.Qc else:

1. if not a constant, use the flow rate just before the time

1. period that exceeds the input t. otherwise, use the

1. last flow rate given if self.Q c["t"][0] > t: return 0 for i in range(1,len(self.Q c["t"])):

if self.Qc["t"][i] > t:

return self.Q_c["vals"] [i-i]

return self.Q c["vals"] [-1]

def get FiltrationRate(self,mass):

... returns the filtration rate (fraction between 0 and 1) of debris through the strainer. (Note the mass is total for a strainer,and there are 20 modules, with the filtration function relating to the per module mass - so we divide by 20 to get the per-module mass.

mass -- amount of debris currently on the strainer (grams) retval - fraction between 0 and 1 indicating how the proportion of mass that is caught and added to the strainer if (mass/20.0) <= self.threshold:

return (mass/20.0)*self.m + self.b else:

return (self.threshold*self.rm + self.b) + (self.a - self.threshold*self.m -

self.b) * (1-scipy.exp(-self.delta * ((mass/20.0)-self.threshold)) )

def getDeltaMassStrainerA(self, masses, t):

"""Calculates the rate of change of mass on strainerA.

masses -- mass of debris in the different parts of the recirculationsystem:

masses[O] = Pool (M__p) masses[l] = Strainer A (M__s _A) masses[21 = Strainer B CM s tB) masses[3) = Strainer C (M__sC) masses[4] = Core Mý__c)

Saturday 14'h March, 2015, 07:39 56 corresponding: keeej(Ostpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages t-- time retval -- rate of change of mass on Strainer A.

return self.getFlowRateStrainerA(t) * (masses[0] / self.V-p)

• self.

getFiltrationRate(masses[1])

def getDeltaMassStrainerB(self, masses, t):

... Calculates the rate of change of mass on strainer B.

masses -- mass of debris in the different parts of the recirculationsystem:

masses[O] = Pool (M__p) masses[i] = Strainer A (M__s__A) masses[2] = Strainer B (M sB) masses[31 = Strainer C (M s__C) masses[4] = Core (M _c) t -- time retval -- rate of change of mass on Strainer B.

return self.getFlowRateStrainerB(t) * (masses[0] / self.V p)

• self.

get FiltrationRate(masses [21) def getDeltaMassStrainerC (self, masses, t):

"""Calculates the rate of change of mass on strainer C.

masses -- mass of debris in the different parts of the recirculationsystem:

masses[O] = Pool (M_..p) masses[I] = Strainer A (M__s _A) masses[2- = Strainer B (Ms_B) masses[31 = Strainer C (Ms__C) masses[4) = Core (Mc) t -- time retval -- rate of change of mass on Strainer C.

return self.getFlowRateStrainerC(t) * (masses[0] / self.V p)

• self.

get FiltrationRate(masses [3])

def get Net PassThroughRat e(self,masses,t):

"""Calculates the weighted average pass-through rate of debris through the strainers and to the core.

result is weighted by flow rate to the core (given by the gamma term and flow rate).

masses -- mass of debris in the different parts of the system:

recirculationsystem:

masses[O] = Pool (M__-P)

Saturday 14 th March, 2015, 07:39 57 corresponding: keeej(9stpegs.corn

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages masses[i] = Strainer A (M sA) masses[21 = Strainer B (M sB) masses[3] = Strainer C (M sC) masses[41 = Core (Mc) t -- time retval -- weighted average of debris filtered by the strainers"""

if self.getFlowRateStrainerA(t) + self.getFlowRateStrainerB(t) + self.

getFlowRateStrainerC(t) = 0: return 1.0 else: return ( self. getFlowRateStrainerA(t) * (1-self. getFiltrationRate(masses

[1])) * (1-self.gamma__a)

+ self.getFlowRateStrainerB(t) * (1-self.getFiltrationRate(masses

[2])) * (1-self.gammab)

+ self.get FlowRateStrainerC(t) * (1-self.getFiltrationRate(masses

[3D)) * (1-self.gamma_c) ) / \

(self.get FlowRateStrainerA(t) * (1-self. gamma.a) +

self.getFlowRateStrainerB(t) * (1-self.gammab) +

self.getFlowRateStrainerCCt) * (1-self. gamma-c) )

def getDeltaMassCore(self, masses, t):

"."" Calculates the rate of change of debris on the core.

return self.getFlowRateCore(t) * (masses[0] / self.V p) * (self.

getNetPassThroughRate(rmasses, t))

def get DeltaMassPool(self,masses,t):

"."" Calculates the rate of change of debris in the pool.

return -1.0*( self. getDeltaMassCore(masses,t)

+ self.getDeltaMassStrainerA(masses, t)

+- self.getDeltaMassStrainerB(masses, t)

+ self. getDeltaMassStrainerC (masses, t) )

def getAllDeltas(self, masses, t):

"""Gets the rate of change of debris in all locations.

return scipy.array( [ self.getDeltaMassPool(masses ,

self.get DeltaMassSt rainerA(masses,t),

self.get DeltaMassStrainerB (masses,t),

self.get DeltaMassStrainerC(masses,t),

self.getDeltaMassCore(masses,t) ] )

def solveForCoreMass(self, t):

"""Runs the ODE integratorfrom Python's ODE library, Saturday 1 4 th March, 2015, 07:39 58 corresponding: keeej acstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages with the delta functions and initial values arrangedin order: pool, strainer A, B, C, and Core.

Note: We use the library's default solver, LSODA, for this set of differential equations."""

return scipy.integrate.odeint (self.get AllDeltas, scipy. array ( [self. M-p_0, self. M s a O, self.M-sbO, self.Ms c O, self. Mc_0]

t, mxstep=10000000 )

def print EchoIn(self, filename = "echoin. csv"):

"""Prints all model parameters to file. Used for debugging and I/O checking. "....

outfile = open(filename,'w')

outfile.write( " Modeluparametersuused: \n\n")

outfile. writeC( FiltrationuFunctionuParameteruValues: \n")

outfile.write("m,%s\n" % self.m) outfile.write("b,%s\n" % self.b) outfile. write( "M c, %s\n" % self.threshold) outfile.write(" delta,%s\n" % self.delta) outfile.write("a,%s\n\n" % self.a) out file.write("InitialuMassesuanduStraineruValues: \n")

outfile.write("M-p 0,%s\n" % self.MpO) outfile.write("V-.p,%s\n" % self.Vp) outfile.write("M__sa .O,%s\n" % self.M s __a 0) outfile.write("Msb O,%s\n" % self.M_ s__b 0) outfile.write("Msc 0,%s\n" % self.M scO) outfile.write(" FlowuRatesuoverutime: \n ")

if type(self. Q-sa) == float: outfile. write(" Q-s-a, %s\n" % self.Q s a) else:

outfile.write("t,Q_,sa\n")

for idx in range(len(self.Q_sa["t"])):

outfile.write("%s,%s\n" % (self.Q s a["t"] [idx],self.Q s a["vals"][

idx]))

outfile.write("k\n")

if type(self.Q-s-b) == float: outfile.write("Q-s-b,%s\n" % self.Q-s-b) else:

outfile. write(" t, Qsb\n")

Saturday 14t" March, 2015, 07:39 59 corresponding: keeej0-stpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages for idx in range(len(self.Q sb["t"])):

outfile.write(" %s,%s\n" % (self.Q_s_b["t"] [idxJ,self.Q s b["vals"]

idx]))

outfile.write(" \n")

if type(self.Q s c) == float: outfile.write("Q s c,%s\n" % self.Q-s-c) else:

outfile.write("t,Qsc\n) for idx in range(len(self.Q sc["t"])):

outfile.write("%s,%s\n" % (self.Q__sc["t"I[idx],self.Qsc["vals"][

idx]))

outfile.write(" \n")

if type(self.Q-c) == float: outflle.write("Q c,%s\n' % self.Q c) else:

outfile.write( t,Qc\n for idx in range(len(self.Q ¢c["t"])):

outfile.write("%s,%s\n" % (self. Q c["t"] [idx] ,self.Q c["vals"] [idx]))

outfile.write(" \n")

def ReadParams(time filename, initialsfilename):

"""Serves as the input reader for this model. Assumes there is one file that reads as a table of time-based inputs and another file with initial and model values, the output is a dictionary that is used to initialize the MassCalculatorclass.

params {}

• read in initials and constants file initialsfile = csv.reader(open(initialsfilename, 'rU'))

for line in initialsfile:

if len(line) > 1:

try: params[line[O)) = float(line[l])

except ValueError: pass

1. read in time-based inputs file timedf = pandas.readcsv(time_filename)

1. print time__df params["Q_s_a"] = {}

params["Q_s_a"]["t"i = time__df.t.values params["Q s a"]["vals"] = time df.Q__sa.values params["Q s b"] = {}

paramst"Q s b"]["t"] = time_df.t.values params["Q_s_b"]["vals"] = timedf.Q__s_b.values params["Q_s_c"] = {}

Saturday 14 th March, 2015, 07:39 60 corresponding: keeej0Pstpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages params["PQsc"][Pt'] = timedf.t.values params["Q s c"]["vals"] = timedf.Q_s_c.values params["Qc"] = {}

params["Q-c"]P"t"] = timedf.t.values params["PQc"P["vals"] = time df. Q_c.values return params if _name == "__mainI.:

timefilename = rawinput("Pleaseuenterutheunameuofutheutime-indexedu input sufile:uu")

1. timefilename = "time.csv" initialsfilename = rawinput("Pleaseuenterutheunameujofutheconstantjinputsu file:u.,")

Winitialsfilename = "const.csv" solver = MassCalculator(ReadParams(time_filename, initials_filename))

timespan = float (rawinput C Pleaseenterutheudesiredutimespanu(minutes):u)

1. timespan = 1000 outfile = raw__input(" Pleaseuenterutheuresultsufilenaneu(nouextension):uu")

Woutfile = "DEMO"

1. createpng = raw input("Creategraph summary of output (yin)? ")

clock = time.timeO t = scipy.linspace(0,timespan,1001) sol = solver.solveForCoreMass(t) .T elapsed = time.timeO) - clock print "Calculationsucompleteduinu" +str (elapsed) +" useconds. uuCreatinguoutputu files."

1. Creating csv table output = open(outfile+".csv",'w')

output.write("t,M-p,M sa, M_sb, Msc, M c\n")

for idx in range(len(sol[0])):

output. writ e(str(t [idx] ) + ," +str(sol [0] [idx] ) + ," +str (sol[1] [idx] ) + ","+st r(sol

[2] [idx] )+ ," +str(sol[3] [idx] )+","+str(sol[4] [idx] ) + "\n")

output.closeO

1. Creating 2x2 figure of plots of debris levels over time.

1. If plotting can't be done here, skip this step.

try:

fig, axes = plt.subplots(2,2) axes[0, 0].plot(t,sol[l])

axes[0, 0] .set_titleC('DebrisuonustraineruAuoverutime')

axesfO, 1].plot(t,sol[21)

Saturday 1 4 th March, 2015, 07:39 61 corresponding: keeej(Kýstpegsxorn

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages axes[0, l].settitle('DebrisuonustraineruBuoverutime')

axesfl, 0].plot(t,sol[31) axes l, 0].settitle('DebrisuonustraineruCuoverutime')

axes[l, l].plot(t,sol[4])

axes[l, 1].settitle('Debrisuonucoreuoverutime')

plt.savefig(outfile+ ".png")

except TypeError: pass

1. print model parameters solver. print EchoIn ()

62 corresponding: keeejt~stpegs.com Saturday 14 Saturday 1 4 th March 2015, Ih March, 07:39 2015, 07:39 62 corresponding: keeej((Ostpegs.coni

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Listing 2: Mass conservation solver, time-dependent inputs t,Q s-a,Q_s b,Q_s_c,Q_c 0.00,7200,7200,7200,610.00 8.33,7200,7200,7200,565.81 41.67,7200,7200,7200,520.19 75.00,7200,7200,7200,419.82 108.33,7200,7200,7200,370.37 141.67,7200,7200,7200,340.83 225.00,7200,7200,7200,319.87 308.33,7200,7200,7200,286.78 641.67,7200,7200,7200,265.56 975.00,7200,7200,7200,220.91 1308.33,7200,7200,7200,197.62 1641.67,7200,7200,7200,182.46 2475.00,7200,7200,7200,171.01 6641.67,7200,7200,7200,151.19 9975.00,7200,7200,7200,107.08 13308.33,7200,7200,7200,90.92 16641.67,7200,7200,7200,80.49 Saturday 1 4 th March, 2015, 07:39 63 corresponding: keeej Qcstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Listing 3: Input listing for the mass conservation solver: constants for High Pool Concentration, High Filtration Efficiency Initial Mass:

M_p_0,249700 M s a_0,0 M sbO0,0 M s c_0,0 M c_0,0 Pool Volume:

V_p,300000 Strainer Recirculation Rates::

gammaa,0 gamma b,0.33 gamma-c,0.33 Filtration Function Parameters (see Ogden Tejada and Morton STP-RIGSI1913VO3

.06):

m,0.0003723 b,0.7059 M-c,790 delta,0.0318 Saturday 1 4 th March, 2015, 07:39 64 corresponding: keeej(9stpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Listing 4: Input listing for the mass conservation solver: constants for High Pool Concentration, Low Filtration Efficiency Initial Mass:

M p_0,249700 M s a_0,0 M sbO0,0 Ms c_0,0 M c_0,0 Pool Volume:

V_p,300000....

Strainer Recirculation Rates::

garnma a,0 gamma-b,0.33 gamma-c,0.33 Filtration Function Parameters (see Ogden Tejada and Morton STP-RIGSI1913VO3

.06):

m,0.0003391 b,0.656 M_c,880 delta,0.0013 65 corresponding: keeejt~stpegs.com Saturday 14 Saturday 1 4 th March, 2015, 1h March, 07:39 2015, 07:39 65 corresponding: keeej(9stpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Listing 5: Input listing for the mass conservation solver: constants for Low Pool Concentration, Low Filtration Efficiency Initial Mass:

M p_0,87068.12 Msa__0,0 M s-b_0,0 M s c_0,0 M c_0,0 Pool Volume:

V_p,550000 Strainer Recirculation Rates::

gamma a,0 gamma-b,0.33 gamma c,0.33 Filtration Function Parameters (see Ogden Tejada and Morton STP-RIGSI1913VO3

.06):

m,0.0003391 b,0.656 M_c,880 delta,0.0013 Saturday 1 4 th March, 2015, 07:39 66 corresponding: keeej Last pegs. corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Listing 6: Input listing for the mass conservation solver: constants for Low Pool Concentration, Low Filtration Efficiency Initial Mass:

M p_0,87068.12 M s a_0,0 M s b.0,0 Msc_0,0 M c_0,0 Pool Volume:

V_p,550000 Strainer Recirculation Rates::

gamma-a,O gamma-b,0.33 gamma-c,0.33 Filtration Function Parameters (see Ogden Tejada and Morton STP-RIGSI1913VO3

.06):

m,0.0003723 b,0.7059 M c,790 delta,0.0318 Saturday 1 4 th March, 2015, 07:39 67 corresponding: keeejUstpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 11 Top-down LOCA frequency solution implementation The following listings are Python source code and the inputs used to generate the results in Section 4.4 (Results). The output of the frequency application is directed to the screen via a 'print' statement (see last four lines of Listing 7). Input files are required for the exceedence frequency quantiles at different break sizes, a weld list that has the number and inside diameter of welds in the plant within the GSI-191 scope, and a list of the Dsma/l from the ROVERD fetch stage. The input files are in the ".CSV" text format (comma separated variables) and can be imported into (for example) the Microsoft application, EXCEL for ease of editing.

NOTE: The frequency results in Table 8, Table 9, Table 10, and Table 11 were not from the Python application but rather a spreadsheet implementation of the top-down method.

In the following, input files for computing the results shown in Table 4 are listed:

1. The arithmetic mean frequency table (from Tregoning et al. (2008)) input is Listing 8.

2. The geometric mean frequency table (from Tregoning et al. (2008)) input is Listing 9.

3. The weld list (ID and count) input is shown in Listing 10.

4. The pipe break table from ROVERD fetch is listed in Listing 11.

Listing 7: Source listing for (5) solution, Alex Zolan, UT Austin, 27 February, 2015 LOCA Frequency Calculator Alex Zolan Updated February 27, 2015 The purpose of the program is to estimate the frequency of critical breaks that can occur We assume that any pipe that has a diameter as large or larger than any critical break size could experience such a break, and that each possible pipe has the same chance of having such a break.

import pandas import scipy class NUREG_1829_Freqs(object):

"""This class manages the NUREG-1829 frequencies as given by an input file, which has the the break size, mean, and 5th, 50th and 95th exceedance break frequencies for a set number of categories."""

Saturday 14"' March, 2015, 07:39 68 corresponding: keeejOstpegs.coni

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages def _init (self,nuregfile):

We start with a dataframe and take the break sizes and each sumimary statistic as their own independent list.

df = pandas.read csv(nureg file)

• self. categories = df. Category.values self.sizes = df.Break-Size.values self.means = df.Mean.values self.P5 = df.P5.values self.P50 = df.P50.values self.P95 = df.P95.values def findFirstExceedingIndex(self,size):

""Finds the index of the first size that is larger than the given size.

size -- break size, in inches retval - index from sizes object"""

assert size >= self.sizes[0], "SizeuoutsidejofuNUREGjfound.uuAborting."

for idx, s in enumerate(self.sizes):

if s >= size: return idx return -1 def get Frequency(self,size,stat):

"""Returns the exceedance frequency of a given break size uses NUREG 1829 values and linear interpolation to find the best .

size -- break size, in inches stat -- desired summary statistic retval - summary statistic frequency for break size"""

idx = self.findFirstExceedingIndex(size) assert idx >= 0, "SizeuoutsidejofuNUREGjFound.juuAborting."

if idx == 0: return self.getStat(0,stat) lower self.getStat(idx-1,stat) upper - self.getStat(idx,stat) frac = (size-self.sizes[idx- 1])/ (self.sizes[idx]-self.sizes[idx- 1])

1. print "Frac Calc ", size,lower,upper,self. sizestidx- 11, self. sizes[idx]

return lower + (upper-lower)*frac def get St at (self, idx,stat):

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NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages

"""Returns a summary statistic based on the object desired.

idx -- index of the desire list to return stat -- desired summary statistic retval - summary statistic frequency from NUREG-1829"""

if stat == "P5": return self.P5[idx]

if stat == "P50": return self.P50(idx]

if stat == "P95": return self.P95[idx]

if stat == "Mean": return self.means[idx]

class LOCAEventCalculator(obj ect):

"""This class acts as the calculatorfor LOCA Events. It calls frequencies from the NUREG_1829_Freqs object, and determines the probability of a particular pipe breaking by finding the number of pipes that could handle such a break.

breaksFile -- location of the file that contains all pipes and the weld break sizes that would cause a significant event weldsFile -- location of the file that contains a summary of the number of welds of each size/type def _init (self, breaksFile,weldsFile):

self.breaksdf = pandas.read_csv(breaksFile) self.welds_df = pandas.readcsv(weldsFile) def get PipesOfExceedingSize(self,breakSize):

"""returns the number of pipes in from the welds dataframe that have a diameter that meets or exceeds a given break size, given the input breakSize."....

return scipy.sum(self.weldsdf[self.weldsdf.pipetype

>= breakSize]. number of welds.values) def get SumOfAllBreaks(self,stat,nuregFile):

"" "calculatesthe expected frequency of LOCA events based on calculating the exceedance frequency of the break size and then dividing by the number of pipes that could have a break of that size in the plant (as given by the welds file). This term is calculated for each pipe in the pipebreaks file (when a nonzero break size is included) and then summed to get the result.

nuregFile -- table of NUREG-1829 frequencies.

retval -- expected frequency of LOCA events/CY.

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NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages nureg = NUREG 1829_Freqs(nuregFile) sum-freqs = 0.0 for i,rowdata in self.breaksdf.iterrowso:

if self.breaksdf.Break-size[i] == 0: continue breakFreq = nureg. getFrequency(self. breaks_df.Breaksize[i],stat) numPipes = self. getPipesOfExceedingSize(self. breaksdf.Breaksize [i) sumfreqs += breakFreq / numPipes

• print self.breaksdf.Break sizetil, break~req,numPipes return sum-freqs if _name- == 11 main ":

weldsFile = raw input (" Pleaseuenter theLnameuofjtheuweldsuinput ufile:uu")

1. weldsFile = "welds.csv" breaksFile = raw input( "Pleaseuenterutheunameuofutheupipe/breakusizesujfile:u

,,)

1. breaksFile = "pipebreaks. csv" nuregFile = raw input("PleaseuenterutheunameuofutheuNUREGufrequenciesufile

UU")

1. nuregFile = "NUREGGM.csv" locas = LOCAEventCalculator(breaksFile,weldsFile)

-#printlocas.breaks__df[locas.breaks_df.Break size > 01

• print locas. welds__df P5Freq = locas.getSumOfAllBreaks( 'P5 ",nuregFile)

P50Freq = locas.getSumOfAllBreaks( "P50",nuregFile)

P95Freq = locas.getSumOfAllBreaks("P95",nuregFile) meanFreq = locas. getSurmOfAllBreaks("Mean",nuregFile) print "Tot aluexpectedufrequencyuofueventsuatuP5:uu" +str(P5Freq) + "uevents/CY print "TotaluexpectedufrequencyuofueventsuatjP50:uu"+str(P5OFreq)+"uevents/

CY"1 print "Tot aluexpectedufrequencyuofueventsatuP95: uu" +str(P95Freq) + "uevents/

Cy" print "Tot aluexp ectedufrequencyofueventsuatuMean:uu" +str(meanFreq) + "u events/CY" Listing 8: Input listing for the Arithmetic Means quantiles. Taken from NUREG-1829, Table 13 Category,Break-Size,P5,P50,Mean,P95 Cat 1,0.5,8. 1OE-04,4.80E-03, 1.OOE-02,3.60E-02 Cat2,1.625,4.20E-05,7.00E-04,3.00E-03,1.20E-02 Saturday 14 th March, 2015, 07:39 71 corresponding: keeejAstpegs- coin

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages Cat3,3,1.30E-06,1.90E-05,7.30E-05,2.90E-04 Cat4,7,6.90E-08,1.30E-06,9.40E-06,3.00E-05 Cat5,14,9.90E-09,2.60E-07,2.40E-06,7.20E-06 Cat6,31,5.90E-09,1.50E-07,1.50E-06,5.20E-06 Listing 9: Input listing for the Geometric Means quantiles. Taken from NUREG-1829, Table 19 Category,BreakSize,P5,P50,P95,Mean Cat 1,0.5,6.80E-05,6.30E-04,7. 1OE-03,1.90E-03 Cat2,1.625,5.OOE-06,8.90E-05,1.60E-03,4.20E-04 Cat3,3,2.14E-07,3.40E-06,6. 1OE-05,1.60E-05 Cat4,7,1.40E-08,3. 1OE-07,6. 10E-06,1.60E-06 Cat5,14,4. 10E- 10,1.20E-08,5.80E-07,2.00E-07 Cat6,31,3.49E- 11,1.19E-09,8.00E-08,2.90E-08 Listing 10: Input listing for the welds in the scope of GSI-191 pipe-typenumberof welds,,Pipe size (stainless schedule 160),

0.612,32,,0.75, 0.815,3,,1, 1.338,9,,1.5, 1.687,85,,2, 2.125,6,,2.5, 2.624,26,,3, 3.438,90,,4, 5.187,88,,6, 6.813,54,,8, 8.5,30,,10, 10.126,131,,12, 12.814,10,,16, 27.5,16,,27.5,Spool/forged 29,20,,29,Spool/forged 31,28,,31,Spool/forged Listing 11: Input listing from the ROVERD fetch stage for the welds in the scope of GSI-191 Number,LineNumber,Location__Name,System,Category,PipeID ,Breaksize 1,2-CV-1122-BB1,0.75-CV-1122-BBl-1,CV Small Bore,6B-1,0.614,0 2,2-CV-1 122-BBI,0.75-CV-1122-BBI-2,CV Small Bore,6B-1,0.614,0 3,2-CV-1124-BB1,0.75-CV-1124-BBI-1,CV Small Bore,6B-1,0.614,0 Saturday 1 4 th March, 2015, 07:39 72 corresponding: keee.j(Ostpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 4,2-CV-1124-BBi,0.75-CV-1124-BBl-2,CV Small Bore,6B-1,0.614,0 5,2-CV-1126-BB1,0.75-CV-1126-BBl-i,CV Small Bore,6B-1,0.614,0 6,2-CV- 1126-BB1,0.75-CV-1126-BB1-2,CV Small Bore,6B-1,0.614,0 7,2-CV-1128-BB1,0.75-CV-1128-BB1-i,CV Small Bore,6B-1,0.614,0 8,2-CV- 1128-BB1,0.75-CV-1128-BBl-2,CV Small Bore,6B-1,0.614,0 9,4-RC-i003-BB1,0.75-RC-iOOl-BB1-lRC Small Bore,6B-1,0.614,0 10,4-RC-1000-BB1,0.75-RC-1002-BB2-1,RC Small Bore,6B-1,0.614,0 11,12-RC-1112-BB1,0.75-RC-1112-BBI-i,RC Small Bore,6B-1,0.614,0 12,8-RC-1114-BB1,0.75-RC-1114-BBl-1,RC Small Bore,6B-1,0.614,0 13,12-RC-1125-BB1,0.75-RC-1125-BBI-i,SI-ACC-CL1 Small Bore,6B-1,0.614,0 14,12-RC-1125-BB1,0.75-RC-1125-BBl-2,SI-ACC-CL1 Small Bore,6B-1,0.614,0 15,4-RC-II26-BBI,0.75-RC-1126-BB1-1,RC Small Bore,6B-l,0.614,0 16,12-RC-1212-BB1,0.75-RC-1212-BB1-I,RC Small Bore,6B-i,0.614,0 17,8-RC-1214-BBI,0.75-RC-1214-BB1-i,RC Small Bore,6B-1,0.614,0 18,12-RC-1221-BBi,0.75-RC-1221-BBi-i,SI-ACC-CL2 Small Bore,6B-i,0.614,0 19,12-RC-1221-BB1,0.75-RC-1221-BBI-2,SI-ACC-CL2 Small Bore,6B-i,0.614,0 20,12-RC-1312-BBi,0.75-RC-1312-BBI-i,RC Small Bore,6B-i,0.614,0 21 ,8-RC-1324-BBi,0.75-RC-1324-BBi-i,RC Small Bore,6B-1,0.614,0 22,4-RC-1422-BBI,0.75-RC-1423-BBI-i,RC Small Bore,6B-i,0.614,0 23,8-SI- 1108-BB 1,0.75-SI- 1130-BB2-1 ,RC Small Bore,6B- 1,0.614,0 24,12-SI-1125-BBi,0.75-SI-ii32-BBI-i,RC Small Bore,6B-i,0.614,0 25,12-SI-1218-BBI,0.75-SI-1218-BBI-1,SI Small Bore,6B-1,0.614,0 26,8-SI-1208-BBI,0.75-SI-1223-BB2-i,RC Small Bore,6B-1,0.614,0 27,12-SI-1315-BBi,0.75-SI-1315-BBI-I,SI-ACC Small Bore,6B-1,0.614,0 28,12-SI-1315-BB1,0.75-SI-1323-BBi-1,SI-ACC Small Bore,6B- 1,0.614,0 29,6-SI-1327-BBI,0.75-SI-1327-BBi-I,SI Small Bore,6B-i,0.614,0 30,8-SI-1327-BBI,0.75-SI-1327-BBI-2,SI Small Bore,6B-i,0.614,0 31,8-SI-1327-BBI,0.75-SI-1327-BBI-3,SI Small Bore,6B-i,0.614,0 32,8-SI-1327-BBI,0.75-SI-1328-BB2-I,SI Small Bore,6B-i,0.614,0 33,6-RC-1003-BBI,I-RC-1003-BBI-I,RC Small Bore,6B-2,0.815,0 34,4-RC-II23-BBI,I-RC-II23-BBI-I,RC Small Bore,6B-2,0.815,0 35,4-RC-1422-BBi,I-RC-1422-BBi-i,RC Small Bore,6B-2,0.815,0 36, 16-RC-1412-NSS,1.5-RC-1412-NSS- i,RC,6A-1,1.338,0 37,2(I.5)-CV-II22-BBI,2(I.5)-CV-II22-BBI-ICV - RCPIA,8C-i,I.338,0 38,2(I.5)-CV-II22-BB1,2(I.5)-CV-I122-BBI-2,CV - RCPIA,8C-I,1.338,0 39,2(i.5)-CV-II24-BBI,2(I.5)-CV-II24-BBI-ICV - RCPIB,8C-i,I.338,0 40,2(i.5)-CV-II24-BBI,2(I.5)-CV-ii24-BBI-2,CV - RCPiB,8C-I,I.338,0 41,2(I.5)-CV-II26-BBI,2(I.5)-CV-II26-BBI-ICV - RCPIC,8C-I,I.338,0 42,2(I.5)-CV-II26-BBI,2(I.5)-CV-II26-BBI-2,CV - RCPiC,8C-i,I.338,0 43,2(i.5)-CV-II28-BBI,2(i.5)-CV-II28-BBI-iCV - RCPiD,8C-i,I.338,0 44,2(1.5)-CV-i128-BBI,2(1.5)-CV-1128-BBI-2,CV - RCPID,8C-i,1.338,0 Saturday 1 4 th March, 2015, 07:39 73 corresponding: keeej (A-ustpegs. com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 45,2-CV-1121-BB1 ,2-CV-1121-BB1-1,CV - PZR Auxiliary Spray Line,8A,1.689,0 46,2-CV-1 121-BBI,2-CV-1 121-BBI-2,CV - PZR Auxiliary Spray Line,8A,1.689,0 47,2-CV- 1121-BBE ,2-CV-1 121-BB1-3,CV - PZR Auxiliary Spray Line,8A,1.689,0 48,2-CV- 1122-BB1 ,2-CV- 1122-BB1- 1,CV - RCP1A,8C-2,1.689,0 49,2-CV-1 122-BBi ,2-CV-1 122-BB1-2,CV - RCP1A,8C-2,1.689,0 50,2-CV- 1122-BBI ,2-CV- 1122-BB1-3,CV - RCP1A,8C-2,1.689,0 51 ,2-CV- 1122-BBI ,2-CV-I 122-BB1-4,CV - RCP1A,8C-2,1.689,0 52,2-CV- 1122-BBI ,2-CV- 1122-BB1-5,CV - RCP1A,8C-2,1.689,0 53,2-CV-1122-BB1 ,2-CV-1 122-BBE-6,CV - RCPIA,8C-2,1.689,0 54,2-CV-1124-BB1,2-CV-1 124-BBl- 1,CV - RCP1B,8C-2,1.689,0 55,2-CV-1 124-BB, 2-CV-1 124-BBl-2,CV - RCPIB,8C-2,1.689,0 56,2-CV-I 124-BB 1,2-CV- 1124-BBE-3,CV - RCP1B,8C-2,1.689,0 57,2-CV- 1 124-BBE 2-CV- 1124-BB1-4,CV - RCPIB,8C-2,1.689,0 58,2-CV- 1 124-BB1 ,2-CV- 1124-BB1-5,CV - RCP1B,8C-2,1.689,0 59,2-CV-1 124-BB ,2-CV- 1124-BBI-6,CV - RCPIB,8C-2,1.689,0 60,2-CV- 1 124-BBl ,2-CV- 1 124-BB1-7,CV - RCPIB,8C-2,1.689,0 61 ,2-CV- 1 124-BBI ,2-CV- 1124-BB 1-8,CV - RCPIB,8C-2,1.689,0 62,2-CV- 1 124-BB ,2-CV- 1124-BB1-9,CV - RCP1B,8C-2,1.689,0 63,2-CV-1 124-BB1,2-CV-1 124-BB1-10,C%]- RCPIB,8C-2,1.689,0 64,2-CV-1124-BB1,2-CV-1 124-BBi-i1,C% ]- RCP1B,8C-2,1.689,0 65,2-CV-1124-BB1 ,2-CV-1 124-BBI-12,C%T - RCP1B,8C-2,1.689,0 66,2-CV- 1 124-BB ,2-CV- 1124-BB 1- 13,C%]- RCP1B,8C-2,1.689,0 67,2-CV-1126-BB 1,2-CV-1126-BB1- 1,CV - RCP1C,8C-2,1.689,0 68,2-CV- 1126-BBE 2-CV- 1 126-BBE-2,CV - RCP1C,8C-2,1.689,0 69,2-CV- 1126-BBE ,2-CV- 1 126-BB1-3,CV - RCP1C,8C-2,1.689,0 70,2-CV- 1126-BBE 2-CV- 1126-BB 1-4,CV - RCP1C,8C-2,1.689,0 71,2-CV-1126-BB1,2-CV-1 126-BBI-5,CV - RCP1C,8C-2,1.689,0 72,2-CV-1 126-BBE,2-CV- 1 126-BB 1-6,CV - RCPIC,8C-2,1.689,0 73,2-CV-1 126-BBI,2-CV-I 126-BBI-7,CV - RCPIC,8C-2,1.689,0 74,2-CV- 1126-BBE,2-CV-1 126-BB1-8,CV - RCP1C,8C-2,1.689,0 75,2-CV- 1126-BBI,2-CV- 1 126-BB1-9,CV - RCP1C,8C-2,1.689,0 76,2-CV-1126-BB1,2-CV-1126-BBl-10,CV - RCP1C,8C-2,1.689,0 77,2-CV-1126-BB1,2-CV-1126-BBl-11,CV - RCPlC,8C-2,1.689,0 78,2-CV-1128-BB1,2-CV-1128-BBE-1,CV - RCP1D,8C-2,1.689,0 79,2-CV-1128-BB1,2-CV-1128-BBE-2,CV - RCP1D,8C-2,1.689,0 80,2-CV-1128-BB1,2-CV-1128-BB1-3,CV - RCP1D,8C-2,1.689,0 81,2-CV-1128-BB1,2-CV-1128-BBE-3A,CV - RCP1D,8C-2,1.689,0 82,2-CV-1128-BB1,2-CV-1128-BBE-3B,CV - RCP1D,8C-2,1.689,0 83,2-CV-1128-BB1,2-CV-I128-BB1-4,CV - RCP1D,8C-2,1.689,0 84,2-CV-1128-BB1,2-CV-1128-BBl-5,CV - RCP1D,8C-2,1.689,0 85,2-CV-1128-BB1,2-CV-1128-BB1-6,CV - RCPID,8C-2,1.689,0 74 corresponding: keeej~istpegs.corn Saturday 14 Saturdkv March, 2015, th March, 1 4 Ih 07:39 2015, 07:39 74 corresponding: keeej9(stpegs.corn

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 86,2-CV-1128-BB1,2-CV-1128-BB1-7,CV - RCP1D,8C-2,1.689,0 87,2-CV-1141-BB1,2-CV-1141-BB1-1,CV - RC Crossover-4,8A, 1.689,0 88,2-CV-1141-BB1,2-CV-1141-BB1-2,CV - RC Crossover-4,8A,1.689,0 89,2-RC-1003-BB1 ,2-RC-1003-BB1-1,PZR Auxiliary Spray Line,5J, 1.689,0 90,2-RC-1003-BB1 ,2-RC- 1003-BB1-2,PZR Auxiliary Spray Line,5J, 1.689,0 91,2-RC-1120-BB1,2-RC-1120-BB1-1,RC,7K,1.689,0 92,2-RC-1120-BB1 ,2-RC-1120-BB1-2,RC,6A-2,1.689,0 93,2-RC-1121-BB1,2-RC- 1121-BB1-1,RC,6A-2,1.689,0 94,2-RC- 1121-BB1 ,2-RC- 1121-BB1-2,RC,6A-2,1.689,0 95,2-RC-1121-BB1 ,2-RC-1121-BB1-3,RC,6A-2,1.689,0 96,2-RC-1121-BB1,2-RC-1121-BB1-3A,RC Drain,6A-2,1.689,0 97,2-RC-1121-BB1 ,2-RC-1121-BB1-3B,RC Drain,6A-2,1.689,0 98,2-RC-1121-BB1,2-RC-1121-BB1-4,RC,6A-2,1.689,0 99,2-RC-1219-BB1 ,2-RC-1219-BB1-1,RC,7K,1.689,0 100,2-RC-1219-BB1 ,2-RC-1219-BB1-2,RC,6A-2,1.689,0 101 ,2-RC- 1220-BB1 ,2-RC-1220-BBl-1,RC,6A-2,1.689,0 102,2-RC-1220-BB1 ,2-RC-1220-BB1-2,RC,6A-2,1.689,0 103,2-RC- 1220-BB1 ,2-RC- 1220-BB1-3,RC,6A-2,1.689,0 104,2-RC-1220-BB1 ,2-RC-1220-BB1-4,RC,6A-2,1.689,0 105,2-RC-1319-BB1 ,2-RC-1319-BBl-1,RC,7K,1.689,0 106,2-RC-1319-BB1,2-RC-1319-BB1-2,RC,6A-2,1.689,0 107,2-RC-1321-BB1,2-RC-1321-BBl-1,RC,6A-2,1.689,0 108,2-RC-1321-BB1,2-RC-1321-BB1-4,RC,6A-2,1.689,0 109,2-RC-1321-BB1 ,2-RC-1321-BB1-5,RC,6A-2,1.689,0 110,2-RC-1321-BB1 ,2-RC-1321-BB1-6,RC,6A-2,1.689,0 111,2-RC-1417-BB1,2-RC-1417-BBl-1,RC,7K,1.689,0 112,2-RC-1417-BB1 ,2-RC-1417-BB1-2,RC,6A-2,1.689,0 113,2-RC-1418-BB1,2-RC-1418-BBl-1,RC,6A-2,1.689,0 114,2-RC-1418-BB1,2-RC-1418-BB1-2,CV - RC Crossover-4,8A,1.689,0 115,2-RC-1418-BB1 ,2-RC-1418-BB1-3,CV - RC Crossover-4,8A, 1.689,0 116,2-RC-1418-BB1,2-RC-1418-BB1-4,RC,6A-2,1.689,0 117,2-RC-1418-BB1,2-RC-1418-BB1-5,RC,6A-2,1.689,0 118,2-RC-1418-BB1,2-RC-1418-BB1-6,RC,6A-2,1.689,0 119,2-RC-1419-BB1,2-RC-1419-BB1-1,CV - RC Crossover-4,8A,1.689,0 120,2-RC-1419-BB1 ,2-RC-1419-BB1-2,CV - RC Crossover-4,8A, 1.689,0 121,2-RC-1419-BB1,2-RC-1419-BB1-3,CV - RC Crossover-4,8A,1.689,0 122,2-RC-1419-BB1,2-RC-1419-BB1-4,RC,6A-2,1.689,0 123,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-5,RC,7K,1.689,0 124,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-6,RC,7K,1.689,0 125,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-5,RC,7K,1.689,0 126,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-7,RC,7K,1.689,0 Saturday 14 th March, 2015, 07:39 75 corresponding: keeejKlstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 127,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-5,RC,7K,1.689,0 128,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-5,RC,7K,1.689,0 129,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-7,RC,7K,1.689,0 130,2.5-RC-1003-BB1,2.5-RC-1003-BB1-1,Pressurizer Surge Line,4D,2.125,0 131 ,2.5-RC-1003-BB1,2.5-RC-1003-BB1-2,Pressurizer Surge Line,4D,2.125,0 132,2.5-RC-1003-BB1,2.5-RC-1003-BB1-3,Pressurizer Surge Line,4D,2.125,0 133,2.5-RC-1003-BB1,2.5-RC-1003-BB1-4,Pressurizer Surge Line,4D,2.125,0 134,2.5-1RC-1003-BB1,2.5-RC-1003-BB1-5,Pressurizer Surge Line,4D,2.125,0 135,2.5-1RC-1003-BB1,2.5-RC-1003- BB1-6,Pressurizer Surge Line,4D,2.125,0 136,3-RC-1003-BB1,3-RC-1003-BB1-1,PZR Auxiliary Spray Line,5B,2.626,0 137,3-RC-1003-BB1,3-RC-1003-BB1-2,PZR Auxiliary Spray Line,5B,2.626,0 138,3-RC-1015-NSS, 3-RC-1015-NSS-1,Pressurizer PORV Line,5D,2.626,0 139,3-RC-1015-NSS,3-RC-1015-NSS-2,Pressurizer PORV Line,5D,2.626,0 140,3-RC-1015-NSS, 3-RC-1015-NSS-3,Pressurizer PORV Line,5B,2.626,0 141,3-RC-1015-NSS, 3-RC-1015-NSS-4,Pressurizer PORV Line,5B,2.626,0 142,3-RC-1015-NSS, 3-1RC-1015-NSS-5,Pressurizer PORV Line,5B,2.626,0 143,3-RC-1015-NSS, 3-1RC-1015-NSS-6,Pressurizer PORV Line,5B,2.626,0 144,3-RC-1015-NSS, 3-RC-1015-NSS-7,Pressurizer PORV Line,5B,2.626,0 145,3-RC-1015-NSS, 3-RC-1015-NSS-8,Pressurizer PORV Line,5B,2.626,0 146,3-RC-1015-NSS,3-RC-1015-NSS-9,Pressurizer PORV Line,5D,2.626,0 147,3-RC-1015-NSS,3-RC-1015-NSS-10,Pressurizer PORV Line,5D,2.626,0 148,3-RC-1015-NSS,3-RC-1015-NSS-11,Pressurizer PORV Line,5B,2.626,0 149,3-RC-1015-NSS,3-RC-1015-NSS-12,Pressurizer PORV Line,5B,2.626,0 150,3-RC-1015-NSS,3-RC-1015-NSS-13,Pressurizer PORV Line,5B,2.626,0 151 ,3-RC-1015-NSS,3-RC-1015-NSS-14,Pressurizer PORV Line,5B,2.626,0 152,3-RC-1015-NSS,3-RC-1015-NSS-15,Pressurizer PORV Line,5B,2.626,0 153,3-RC-1015-NSS,3-RC-1015-NSS-16,Pressurizer PORV Line,5B,2.626,0 154,3-RC-1106-BB1,3-RC-1106-BB1-25,SI - Capped,7J,2.626,0 155,3-RC-1206-BB1 ,3-RC-1206-BB1-28,SI - Capped,7 J,2.626,0 156,3-RC-1306-BB1 ,3-RC-1306-BB1-28,SI - Capped,7J,2.626,0 157,3-RC-1406-BB1,3-RC-1406-BB1-25,SI - Capped,7 J,2.626,0 158,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-7,RC,7J,2.626,0 159,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-6,RC,7J,2.626,0 160,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-6,RC,7J,2.626,0 161,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-6,RC,7J,2.626,0 162,4-CV-1001-BB1,4-CV-1001-BBl-1,CV - RC Crossover-3,8B,3.438,0 163,4-CV-1001-BB1,4-CV-1001-BB1-2,CV - RC Crossover-3,8B,3.438,0 164,4-CV-1118-BB1,4-CV-1118-BBl-1,CV - RC Coldleg 1,8B,3.438,0 165,4-CV-1118-BB1,4-CV-1118-BB1-2,CV - RC Coldleg 1,8B,3.438,0 166,4-CV-1120-BB1,4-CV-1120-BBl-1,CV - RC Coldleg 3,8B,3.438,0 167,4-CV-1120-BB1,4-CV-1120-BB1-2,CV - RC Coldleg 3,8B,3.438,0 Saturday 14th March, 2015, 07:39 76 corresponding: keeejLQstpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 168,4-RC- 1000-BB1 ,4-RC- 1000-BB I-1,Pressurizer Spray, 5C,3.438,0 169,4-RC- 1000-BB1,4-RC- 1000-BB 1-2,Pressurizer Spray,5C,3.438,0 170,4-RC-1000-BB1 ,4-RC-1000-BB1-3,Pressurizer Spray,5C,3.438,0 171 ,4-RC- 1000-BB1 .4-RC- 1000-BB 1-4,Pressurizer Spray,5C,3.438,0 172,4-RC-1000-BB1 ,4-RC-1000-BB1-5,Pressurizer Spray,5C,3.438,0 173,4-RC-1000-BB1, 4-RC-1000-BB1-6,Pressurizer Spray,5C,3.438,0 174,4-RC- 1000-BB1 ,4-RC-1000-BB1-7,Pressurizer Spray, 5C,3.438,0 175,4-RC-1000-BB1,4-RC-1000-BB1-8,Pressurizer Spray,5C,3.438,0 176,4-RC-1003-BB1 ,4-RC-1003-BBl-1,Pressurizer Spray,5C,3.438,0 177,4-RC- 1003-BB1, 4-RC-1003-BB1-2,Pressurizer Spray,5C,3.438,0 178,4-RC-1003-BB1 ,4-RC-1003-BB1-3,Pressurizer Spray,5C,3.438,0 179 ,4-RC- 1003-BB1 ,4-RC- 1003-BB 1-4,Pressurizer Spray,5C,3.438,0 180,4-RC- 1123-BB1 ,4-RC- 1123-BB 1-1 Pressurizer Spray, 51,3.438,0 181 ,4-RC-1123-BB1, 4-RC-1 123-BB1-2, Pressurizer Spray,5C,3.438,0 182,4-RC-1 123-BB1 ,4-RC-1 123-BB 1-3, Pressurizer Spray, 5C,3.438,0 183,4-RC- 1123-BB1, 4-RC- 1123-BB 1-4, Pressurizer Spray,5C,3.438,0 184,4-RC-1 123-BB1 ,4-RC-1123-BB1-5, Pressurizer Spray,5C,3.438,0 185,4-RC-1123-BB1,4-RC-1123-BB1-6,Pressurizer Spray,5C,3.438,0 186,4-RC-1123-BB1,4-RC-1123-BB1-7,Pressurizer Spray,5C,3.438,0 187,4-RC-1123-BB1,4-RC-1123-BB1-8, Pressurizer Spray,5C,3.438,0 188,4-RC- 1123-BB1 .4-RC- 1123-BB 1-9, Pressurizer Spray,5C,3.438,0 189,4-RC-1 123-BB1,4-RC-1123-BB1-10,Pressurizer Spray,5C,3.438,0 190,4-RC-1 123-BBi ,4-RC-1123-BB1- 11,Pressurizer Spray,5C,3.438,0 191,4-RC-1123-BB1,4-RC-1123-BB1-12,Pressurizer Spray,5C,3.438,0 192,4-RC-1 123-BBi ,4-RC-1123-BB1-13, Pressurizer Spray,5C,3.438,0 193,4-RC- 1123-BB1,4-RC- 1123-BB1-14, Pressurizer Spray,5C,3.438,0 194,4-RC-1 123-BB1,4-RC- 1i23-BB1-15, Pressurizer Spray,5C,3.438,0 195,4-RC-1123-BB1,4-RC-1123-BBi-16,Pressurizer Spray,5C,3.438,0 196,4-RC- 1 123-BB1,4-RC- 1123-BB 1-17, Pressurizer Spray,5C,3.438,0 197,4-RC-1 123-BB1,4-RC-1 123-BB1-18, Pressurizer Spray,5C,3.438,0 198,4-RC- 1123-BB1,4-RC- 1123-BB 1-19, Pressurizer Spray,5C,3.438,0 199,4-RC- 1123-BB 1,4-RC- 1123-BB 1-20, Pressurizer Spray,5C,3.438,0 200,4-RC-1126-BB1,4-RC-1126-BBl-1,CV - RC Coldleg 1,8B,3.438,0 201,4-RC-1126-BB1,4-RC-1126-BBi-2,CV - RC Coldleg 1,8B,3.438,0 202,4-RC-1126-BB1,4-RC-1126-BB1-3,CV - RC Coldleg 1,8B,3.438,0 203,4-RC-1126-BB1,4-RC-1126-BB1-4,CV - RC Coldleg 1,8B,3.438,0 204,4-RC- 1126-BB1,4-RC- 1126-BB1-5,CV - RC Coldleg 1,8B,3.438,0 205,4-RC- 1126-BB 1,4-RC-1126-BBi-6,CV - RC Coldleg 1,8E,3.438,0 206,4-RC-1320-BB1,4-RC-1320-BBl-1,CV - RC Crossover-3,8F,3.438,0 207,4-RC-1320-BB1,4-RC-1320-BBi-2,CV -. RC Crossover-3,8D,3.438,0 208,4-RC-1320-BB1,4-1C-1320-BBi-3,CV - RC Crossover-3,8D,3.438,0 Saturday 1 4 th March, 2015, 07:39 77 corresponding: keeej Calstpegs.corn

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 209,4-RC-1320-BB1,4-RC-1320-BB1-4,CV - RC Crossover-3,8D,3.438,0 210,4-RC-1320-BB1 ,4-RC-1320-BB1-5,CV - RC Crossover-3,8D,3.438,0 211,4-RC- 1320-BB1,4-RC- 1320-BB1-6,CV - RC Crossover-3,8D,3.438,0 212,4-RC-1320-BB1 ,4-RC-1320-BB1-7,CV - RC Crossover-3,8D,3.438,0 213,4-RC-1320-BB1,4-RC-1320-BB1-8,CV - RC Crossover-3,8B,3.438,0 214,4-RC-1320-BB1 ,4-RC-1320-BB1-9,CV - RC Crossover-3,8B,3.438,0 215,4-RC-1320-BB1,4-RC-1320-BBI-10,CV - RC Crossover-3,8B,3.438,0 216,4-RC-1320-BB1 ,4-RC-1320-BBl-11,CV - RC Crossover-3,8B,3.438,0 217,4-RC-1320-BB1,4-RC-1320-BB1-12,CV - RC Crossover-3,8B,3.438,0 218,4-RC-1323-BB1 ,4-RC-1323-BBl-1,CV - RC Coldleg 3,8B,3.438,0 219,4-RC-1323-BB1,4-RC-1323-BB1-2,CV - RC Coldleg 3,8B,3.438,0 220,4-RC-1323-BB1,4-RC-1323-BB1-3,CV - RC Coldleg 3,8B,3.438,0 221 ,4-RC-1323-BB1 ,4-RC-1323-BB1-4,CV - RC Coldleg 3,8E,3.438,0 222,4-RC-1420-BB1 ,4-RC-1420-BBl-1,SI,7I,3.438,0 223,4-RC-1422-BB1,4-RC-1422-BB1-1, Pressurizer Spray,51,3.438,0 224,4-RC- 1422-BB1 ,4-RC- 1422-BB 1-2, Pressurizer Spray, 5C,3.438,0 225,4-RC-1422-BB1,4-RC-1422-BB1-3, Pressurizer Spray,5C,3.438,0 226,4-RC- 1422-BB1,4-RC- 1422-BB1-4,Pressurizer Spray,5C,3.438,0 227 ,4-RC- 1422-BB1 ,4-RC- 1422-BB 1-5, Pressurizer Spray,5C,3.438,0 228,4-RC-1422-BB1, 4-RC-1422-BB1-6, Pressurizer Spray,5C,3.438,0 229,4-RC-1422-BB1 ,4-RC-1422-BB1-7, Pressurizer Spray,5C,3.438,0 230,4-RC-1422-BB1, 4-RC-1422-BB1-8, Pressurizer Spray,5C,3.438,0 231,4-RC-1422-BB1,4-RC-1422-BB1-9, Pressurizer Spray,5C,3.438,0 232,4-RC-1422-BB1, 4-RC-1422-BB1-10,Pressurizer Spray,5C,3.438,0 233,4-RC- 1422-BB1,4-RC- 1422-BB 1-11, Pressurizer Spray,5C,3.438,0 234,4-RC-1422-BB1,4-RC-1422-BB1-12, Pressurizer Spray,5C,3.438,0 235,4-RC-1422-BB1,4-RC-1422-BB1-13, Pressurizer Spray,5C,3.438,0 236,4-RC-1422-BB1,4-RC-1422-BB1-14, Pressurizer Spray,5C,3.438,0 237,4-RC-1422-BB1,4-RC- 1422-BB1-15, Pressurizer Spray,5C,3.438,0 238,4-RC-1422-BB1,4-RC-1422-BB1-16, Pressurizer Spray,5C,3.438,0 239,4-RC- 1422-BB1,4-RC- 1422-BB 1-17, Pressurizer Spray,5C,3.438,0 240,4-RC- 1422-BB 1,4-RC- 1422-BB 1-18, Pressurizer Spray,5C,3.438,0 241,4-RC- 1422-BB1,4-RC- 1422-BB 1-19, Pressurizer Spray,5C,3.438,0 242,4-RC- 1422-BB 1,4-RC- 1422-BB 1-20, Pressurizer Spray, 5C,3.438,0 243,4-RC- 1422-BB1,4-RC- 1422-BB 1-21, Pressurizer Spray,5C,3.438,0 244,4-RC- 1422-BB1,4-RC- 1422-BB 1-22 Pressurizer Spray,5C,3.438,0 245,4-RC- 1 422-BB1,4-RC- 1422-BB1-23, Pressurizer Spray,5C,3.438,0 246,27.5-RC-1103-NSS - LOOP 1,27.5-RC-1103-NSS-3,RC,7I,3.438,0 247,27.5-RC-1103-NSS - LOOP 1,27.5-RC-1103-NSS-5,CV,8E,3.438,0 248,27.5-RC-1303-NSS - LOOP 3,27.5-RC-1303-NSS-4,CV,8E,3.438,0 249,27.5-RC-1403-NSS - LOOP 4,27.5-RC-1403-NSS-3,RC,7I,3.438,0 Saturday 1 4 th March, 2015, 07:39 78 corresponding: keeej L-0st pegs. con i

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 250,27.5-RC-1403-NSS - LOOP 4,27.5-RC-1403-NSS-4,RC,71,3.438,0 251,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-7,RC,7I,3.438,0 252,6-RC- 1003-BB1,6-RC- 1003-BB 1-1,Pressurizer Spray,5E,5.189,0 253,6-RC- 1003-BB1,6-RC- 1003-BB1-2,Pressurizer Spray,5E,5.189,0 254,6-RC- 1003-BB 1,6-RC- 1003-BB 1-3,Pressurizer Spray,5E,5.189,0 255,6-RC- 1003-BB1,6-RC- 1003-BB 1-4,Pressurizer Spray,5A,5.189,0 256,6-RC- 1003-BB1,6-RC- 1003-BB 1-5,Pressurizer Spray,5A,5.189,0 257,6-RC-1003-BB1,6-RC-1003-BB1-6,Pressurizer Spray,5A,5.189,0 258,6-RC-1003-BB1,6-RC-1003-BBl-7,Pressurizer Spray,5A,5.189,0 259,6-RC-1003-BB1,6-RC-1003-BB1-8,Pressurizer Spray,5A,5.189,0 260,6-RC- 1003-BB1, 6-RC- 1003-BB1-9,Pressurizer Spray,5A,5.189,0 261 ,6-RC-1003-BB1 ,6-RC-1003-BB1-9A,Pressurizer Spray,5A,5.189,0 262,6-RC-1003-BB1,6-RC-1003-BB1-9B,Pressurizer Spray,5A,5. 189,0 263,6-RC-1003-BB1, 6-RC-1003-BB1-10,Pressurizer Spray,5A,5.189,0 264,6-RC- 1003-BB1, 6-RC- 1003-BBI-1 1,Pressurizer Spray,5A,5.189,0 265,6-RC-1003-BB1,6-RC-1003-BB1-11A,Pressurizer Spray,5A,5.189,0 266,6-RC-1003-BB1 ,6-RC-1003-BB1-11B,Pressurizer Spray,5A,5.189,0 267,6-RC- 1003-BB1, 6-RC- 1003-BB 1- 12,Pressurizer Spray,5A,5.189,0 268,6-RC-1003-BB1 ,6-RC-1003-BB1-13,Pressurizer Spray,5A,5. 189,0 269,6-RC-1003-BB1,6-RC- 1003-BB1-13A,Pressurizer Spray,5A,5.189,0 270,6-RC-1003-BB1 ,6-RC-1003-BB1-14,Pressurizer Spray,5H,5.189,0 271,6-RC-1003-BB1,6-RC-1003-BB1-PRZ-1-N2-SE,Pressurizer Spray,5F,5.189,0 272,6-RC- 1004-NSS, 6-RC-1004-NSS-1, Pressurizer SRV Line,5H,5.189,0 273,6-RC-1004-NSS, 6-RC-1004-NSS-2, Pressurizer SRV Line,5E,5.189,0 274,6-RC-1004-NSS, 6-RC-1004-NSS-3, Pressurizer SRV Line,5E,5.189,0 275,6-RC-1004-NSS, 6-RC-1004-NSS-4, Pressurizer SRV Line,5E,5.189,0 276,6-RC- 1004-NSS, 6-RC-1004-NSS-5, Pressurizer SRV Line,5A,5.189,0 277,6-RC-1004-NSS, 6-RC-1004-NSS-6, Pressurizer SRV Line,5A,5.189,0 278,6-RC- 1004-NSS, 6-RC- 1004-NSS-7, Pressurizer SRV Line,5A,5.189,0 279,6-RC- 1004-NSS, 6-RC- 1004-NSS-PRZ- 1-N3-SE,Pressurizer SRV Line,5F,5.189,0 280,6-RC-1009-NSS,6-RC-1009-NSS-1,Pressurizer SRV Line,5H,5.189,0 281 ,6-RC- 1009-NSS, 6-RC- 1009-NSS-2,Pressurizer SRV Line,5E,5.189,0 282,6-RC-1009-NSS, 6-RC-1009-NSS-3,Pressurizer SRV Line,5E,5.189,0 283,6-RC-1009-NSS,6-RC-1009-NSS-4,Pressurizer SRV Line,5E,5.189,0 284,6-RC- 1009-NSS, 6-RC- 1009-NSS-5,Pressurizer SRV Line,5A,5.189,0 285,6-RC-1009-NSS, 6-RC-1009-NSS-6,Pressurizer SRV Line,5A,5.189,0 286,6-RC- 1009-NSS, 6-RC- 1009-NSS-7,Pressurizer SRV Line,5A,5.189,0 287,6-RC-1009-NSS, 6-RC-1009-NSS-8,Pressurizer SRV Line,5A,5.189,0 288,6-RC- 1009-NSS, 6-RC- 1009-NSS-9,Pressurizer SRV Line,5A,5.189,0 289,6-RC-1009-NSS,6-RC-1009-NSS-PRZ-1-N4C-SE,Pressurizer SRV Line,5F,5.189,0 290,6-RC-1012-NSS,6-RC-1012-NSS-1,Pressurizer SRV Line,5H,5.189,0 Saturdav 1 4 th March, 2015, 07:39 79 corresponding: keeejAstpegs.coni

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 291 ,6-RC-1012-NSS,6-RC-1012-NSS-2, Pressurizer SRV Line,5E,5.189,0 292,6-RC- 1012-NSS,6-RC- 101 2-NSS-3, Pressurizer SRV Line,5E,5.189,0 293,6-RC-1012-NSS,6-RC-1012-NSS-4, Pressurizer SRV Line,5E,5.189,0 294,6-RC-1012-NSS, 6-RC-1012-NSS-5, Pressurizer SRV Line,5E,5.189,0 295,6-RC-1012-NSS,6-RC-1012-NSS-6, Pressurizer SRV Line,5E,5.189,0 296,6-RC-1012-NSS,6-RC-1012-NSS-7,Pressurizer SRV Line,5A,5.189,0 297,6-RC- 1012-NSS, 6-RC- 1012-NSS-8, Pressurizer SRV Line,5A,5.189,0 298,6-RC-1012-NSS,6-RC-1012-NSS-9,Pressurizer SRV Line,5A,5.189,0 299,6-RC-1012-NSS, 6-RC-1012-NSS-10,Pressurizer SRV Line,5A,5.189,0 300,6-RC-1012-NSS,6-RC-1012-NSS-11,Pressurizer SRV Line,5A,5.189,0 301,6-RC-1012-NSS,6-1RC-1012-NSS-PRZ-1-N4B-SE,Pressurizer SRlV Line,5F,5.189,0 302,6-RC-1015-NSS,6-RC-1015-NSS- 1 Pressurizer P'ORV Line,5E,5.189,0 303,6-RC-1015-NSS,6-RC-1015-NSS-2, Pressurizer P'ORV Line,5E,5.189,0 304,6-RC-1015-NSS,6-RC-1015-NSS-3, Pressurizer P 'OR'! Line,5E,5.189,0 305,6-RC-1015-NSS,6-RC-1015-NSS-4, Pressurizer P ORV Line,5E,5.189,0 306,6-RC-1015-NSS,6-RC-1015-NSS-5, Pressurizer P ORV Line,5E,5.189,0 307,6-RC-1015-NSS,6-RC-1015-NSS-6, Pressurizer P'ORV Line,5E,5.189,0 308,6-RC-1015-NSS, 6-RC-1015-NSS-7, Pressurizer P ORV Line,5E,5.189,0 309,6-RC-1015-NSS, 6-RC-1015-NSS-8, Pressurizer P'ORV Line,5E,5.189,0 310,6-RC-1015-NSS, 6-RC-1015-NSS-9, Pressurizer P PORV Line,5E,5.189,0 311 ,6-RC-1015-NSS,6-RC-1015-NSS-10,Pressurizer PORNI" Line,5E,5.189,0 312,6-ROC-1015-NSS,6-RC-1015-NSS-11,Pressurizer PORN I Line,5E,5.189,0 313,6-RC-1015-NSS,6-RC-1015-NSS-12,Pressurizer PORN I Line,5E,5.189,0 314,6-1RC-1015-NSS, 6-RC-1015-NSS-13,Pressurizer POR\I Line,5E,5.189,0 315,6-RC-1015-NSS,6-RC-1015-NSS-14,Pressurizer PORN I Line,5E,5.189,0 316,6-1cC-1015-NSS,6-RC-1015-NSS-15,Pressurizer PORN I Line,5E,5.189,0 317,6-SI-1108-BB1,6-SI-1108-BB1-1,SI,7H,5.189,0 318,6-SI-1108-BB1,6-SI-1108-BB1-2,SI,7H,5.189,0 319,6-SI- 1108-BB1,6-SI-1108-BBI-3,SI,7H,5.189,0 320,6-SI- 1108-BB1,6-SI-1108-BB1-4,SI,7H,5.189,0 321,6-SI-1111-BB1,6-SI-1 1111-BB1-1,SI,7H,5.189,0 322,6-SI-1111-BB1,6-SI-1 111-BB1-2,SI,7H,5.189,0 323,6-SI- 1208-BB1,6-SI-1208-BB1-1,SI,7H,5.189,0 324,6-SI- 1208-BB1,6-SI- 1208-BB1-2,SI,7H,5.189,0 325,6-SI- 1208-BB1,6-SI-1208-BB1-3,SI,7H,5.189,0 326,6-SI- 1208-BB1,6-SI- 1208-BB 1-4,SI,7H,5.189,0 327,6-SI-1211-BB1,6-SI-1211-BB1-1,SI,7H,5.189,0 328,6-SI-1211-BB1,6-SI-1211-BB1-2,SI,7H,5.189,0 329,6-SI- 1308-BB1,6-SI- 1308-BB1-1,RH,7H,5.189,0 330,6-SI- 1308-BB 1,6-SI- 1308-BB1-2,RH,7H,5.189,0 331,6-SI- 1308-BB1,6-SI- 1308-BB1-3,RH,7H,5.189,0 80 corresponding: keeej~stpegs.coin Saturday Saturday Ih March, 144 th 1 2015, 07:39 March, 2015, 07:39 80 corresponding: keeej Abst pegs. com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 332,6-SI- 1308-BB 1,6-SI- 1308-BB1-4,RH,7H,5.189,0 333,6-SI- 1327-BB1 ,6-SI- 1327-BB 1- 1,SI,7H,5.189,0 334,6-SI- 1327-BB 1,6-SI- 1327-BB1-2,SI,7H,5.189,0 335,6-SI- 1327-BB 1,6-SI- 1327-BB 1-3,SI,7H,5.189,0 336,6-SI- 1327-BB 1,6-SI- 1327-BB 1-4,SI,7H,5.189,0 337,6-SI- 1327-BB 1,6-SI- 1327-BB 1-5,SI,7H,5.189,0 338,6-SI- 1327-BB 1,6-SI- 1327-BB 1-6,SI,7H,5.189,0 339,6-SI- 1327-BB1,6-SI- 1327-BB I-7,SI,7H,5.189,0 340,8-RC- 11 14-BB1 ,8-RC- 11 14-BBl- 1,SI,7B,6.813,0 341 ,8-RC- 11 14-BB1,8-RC-11 14-BB1-2,SI,7B,6.813,0 342,8-RC- 11 14-BB1,8-RC- 11 14-BBl-3,SI,7B,6.813,0 343,8-RC- 11 14-BB1,8-RC- 1114-BB1-4,SI,7G,6.813,0 344,8-RC- 11 14-BB1,8-RC- 11 14-BBl-5,SI,7G,6.813,0 345,8-RC-11 14-BB1,8-RC- 1114-BBl-6,SI,7G,6.813,0 346,8-RC-1214-BB1 ,8-RC-1214-BB1- 1,SI,7B,6.813,0 347,8-RC- 1214-BB1 ,8-RC- 1214-BB 1-2,SI,7B,6.813,0 348,8-RC- 1214-BB1 ,8-RC- 1214-BB1-3,SI,7B,6.813,0 349,8-RC-1214-BB1,8-RC-1214-BB1-4,SI,7G,6.813,0 350,8-RC-1214-BB 1,8-RC-1214-BB1-5,SI,7G,6.813,0 351,8-RC-1214-BB1,8-RC-1214-BB1-6,SI,7G,6.813,0 352,8-RC- 1324-BB1 ,8-RC- 1324-BB1- 1,SI,7B,6.813,0 353,8-RC-1324-BB1 ,8-RC- 1324-BB1-2,SI,7B,6.813,0 354,8-RC- 1324-BB1 ,8-RC- 1324-BB1-3,SI,7B,6.813,0 355,8-RC-1324-BB1,8-RC-1324-BB1-4,SI,7G,6.813,0 356,8-RC- 1324-BB1 ,8-RC- 1324-BB1-5,SI,7G,6.813,0 357,8-RC- 1324-BB1 ,8-RC- 1324-BB1-6,SI,7G,6.813,0 358,8-RH-1108-BB1,8-RH- 1 108-BB1-1,RH,7G,6.813,0 359,8-RH- i 108-BB1 8-RH- 1108-BB1-2,RH,7G,6.813,0 360,8-RH-iI 12-BB1 ,8-RH- 1 12-BB1-1,RH,7G,6.813,0 361,8-RH-i 12-BB1,8-RH- 11 12-BB1- 1A,RH,7G,6.813,0 362,8-RH- 1112-BB 1,8-RH- 1112-BB 1-2,RH,7G,6.813,0 363,8-RH- 1208-BB 1,8-RH- 1208-BB 1- 1,RH, 7G,6.813,0 364,8-RH- 1208-BB1,8-RH- 1208-BB1-2,RH,7G,6.813,0 365,8-RH- 1212-BB 1,8-RH- 1212-BB 1-1,RH,7G,6.813,0 366,8-RH- 1212-BB1,8-RH- 1212-BB 1-2,RH,7G,6.813,0 367,8-RH-1308-BB1,8-RH-1308-BB1-1,RH,7G,6.813,0 368,8-RH- 1308-BB1,8-RH- 1308-BB 1-2,RH,7G,6.813,0 369,8-RH-1315-BB 1,8-RH-1315-BB 1-1 ,RH,7G,6.813,0 370,8-SI- 1108-BB 1,8-SI- l108-BB1-1,SI,7G,6.813,0 371,8-SI-1108-BB1,8-SI-1 108-BB1-2,SI,7G,6.813,0 372,8-SI- 1108-BB 1,8-SI-1 108-BB 1-3,SI,7G,6.813,0 Saturday 1 4 th March, 2015, 07:39 81 corresponding: keeejOstpegsxom

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 373,8-SI-1108-BB1,8-SI-i i08-BBi-4,SI,7G,6.813,0 374,8-SI- 1108-BB1 ,8-SI-1108-BB1-5,SI,7C,6.813,0 375,8-SI-1208-BB1 ,8-SI-1208-BB1-1,SI,7G,6.813,0 376,8-SI-1208-BB1 ,8-SI-1208-BB1-2,SI,7G,6.813,0 377,8-SI-1208-BB1 ,8-SI-1208-BB1-3,SI,7G,6.813,0 378,8-SI-1208-BB1,8-SI- 1208-BB1-3A,SI,7G,6.813,0 379,8-SI-1208-BB1 ,8-SI-1208-BB1-4,SI,7C,6.813,0 380,8-SI-1327-BB1,8-SI-1327-BB1-i,SI,7G,6.813,0 381,8-SI-1327-BB1 ,8-SI-1327-BB1-2,SI,7G,6.813,0 382,8-SI-1327-BB1 8-SI-1327-BB1-3,SI,7G,6.813,0 383,8-SI-1327-BB1,8-SI-1327-BB1-4,SI,7G,6.813,0 384,8-SI-1327-BB1 ,8-SI-1327-BB1-5,SI,7G,6.813,0 385,8-SI-1327-BB1 ,8-SI-1327-BB1-6,SI,7G,6.813,0 386,8-SI-1327-BB1,8-SI-1327-BB1-7,SI,7G,6.813,0 387,8-SI-1327-BB1 ,8-SI-1327-BB1-8,SI,7G,6.813,0 388,8-SI-1327-BB1 ,8-SI-1327-BB1-9,SI,7G,6.813,0 389,8-SI-1327-BB1,8-SI-1327-BBl-10,SI,7G,6.813,0 390,8-SI-1327-BB1 ,8-SI-1327-BBi-11,SI,7C,6.813,0 391,29-RC-1101-NSS - LOOP 1,29-RC-1101-NSS-2,SI,7G,6.813,0 392,29-RC-1201-NSS - LOOP 2,29-RC-1201-NSS-2,SI,7G,6.813,0 393,29-RC-1301-NSS - LOOP 3,29-RC-1301-NSS-2,SI,7G,6.813,0 394,10-RH-1108-BB1 ,10-RH-1108-BBI-I,RH,7F,8.5,0 395,10-RH-1108-BB1,10-AH-1108-BB1-iA,RH,7F,8.5,0 396,10-RH-1108-BB1 ,10-RH-1108-BB1-2,RH,7F,8.5,0 397,10-RH-1108-BB1 ,10-RH-1108-BB1-3,RH,7F,8.5,0 398,10-RH-1108-BB1,10-RH-1108-BB1-4,RH,7F,8.5,0 399,10-RH-1108-BB1 ,10-RH-1108-BB1-5,RH,7F,8.5,0 400,10-RH-1108-BB1,10-RH-1108-BBI-6,RH,7F,8.5,0 401,10-RH-1108-BB1,10-RH-1108-BB1-7,RH,7F,8.5,0 402, 10-RH-1108-BB1 ,10-RH-1108-BB1-8,RH,7F,8.5,0 403,10-RH-1108-BB1 ,10-RH-1108-BBi-9,RH,7F,8.5,0 404,10-RH-1108-BB1 ,10-RH-1108-BB1-10,RH,7F,8.5,0 405,10-RH-1208-BB1,10-RH-1208-BBI-1,RH,7F,8.5,0 406, 10-RH-1208-BB1 ,10-RH-1208-BBi-2,RH,7F,8.5,0 407,10-RH-1208-BB1 ,10-RH-1208-BB1-3,RH,7F,8.5,0 408, 10-IRH-1208-BB1 ,10-RH-1208-BB1-4,RH,7F,8.5,0 409,10-RH-1208-BB1 ,10-RH-1208-BBi-5,RH,7F,8.5,0 410,10-RH-1208-BB1 ,10-RH-1208-BB1-6,RH,7F,8.5,0 411,10-RH-1208-BB1 10-RH-1208-BB1-7,RH,7F,8.5,0 412,10-RH-1208-BB1,10-RH-1208-BBI-8,RH,7F,8.5,0 413, 10-RH-1208-BBI ,10-RH-1208-BB1-9,RH,7F,8.5,0 Saturday 1 4 th March, 2015, 07:39 .82 corresponding: keeej@stpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 414, 10-RH-1208-BB1, 10-RH-1208-BB1-10,RH,7F,8.5,0 415,10-RH-1208-BB1 ,10-RH-1208-BBI-1 1,RH,7F,8.5,0 416, 10-RH-1308-BB1, 10-RH-1308-BB1-1,RH,7F,8.5,0 417, 10- RH-1308-BB1 10-RH-1308-BB1-2,RH,7F,8.5,0 418, 10-RH-1308-BB1 10-RH-1 308-BB1-3,RH,7F,8.5,0 419, 10-RH-1308-BB1, 10-RH-1308-BB1-4,RH,7F,8.5,0 420, 10-RH-1308-BB1, 10-RH-1308-BB1-5,RH,7F,8.5,0 421, 10-RH- 1308-BB1, 10-RH-1308-BB1-6,RH,7F,8.5,0 422, 10-RH-1308-BB1, 10-RH-1308-BB 1-7,RH,7F,8.5,0 423, 10-RH- 1308-BB1, 10-RH-1308-BB1-8,RH,7F,8.5,0 424,12-RC- 11 12-BB1, 12-RC-1 1 12-BB1-1 ,RHR-Suction,7E, 10.126,0 425, 12-RC- 11 12-BB1, 12-RC- 11 12-BB 1-2,RHR-Suction,7A, 10.126,0 426, 12-RC- 11 12-BB1, 12-RC- 1112-BB 1-3,RHR-Suction,7A, 10.126,0 427, 12-RC- 11 12-BB1 ,12-RC-1 1 12-BB1-4,RHR-Suction,7A, 10.126,0 428, 12-RC- 1112-BB1, 12-RC-1 1 12-BB1-5,RHR-Suction,7A, 10.126,0 429,12-RC- 11 12-BB1, 12-RC- 11 12-BB1-6,RHR-Suction,7A,10. 126,0 430, 12-RC- 11 12-BB1, 12-RC-1 1 12-BB1-7,RHR-Suction,7A, 10.126,0 431 ,12-RC- 11 12-BB1, 12-RC-1 1 12-BB 1-8,RHR-Suction,7A, 10. 126,0 432, 12-RC- 11 12-BB1, 12-RC- 11 12-BB 1-9,RHR-Suction,7E, 10.126,0 433, 12-RC- 1112-BB1, 12-RC-1 1 12-BBl-10,RHR-Suction,7E, 10.126,0 434,12-RC-11 12-BB1 12-RC- 11 12-BBl- 11,RHR-Suction,7E,10. 126,0 435, 12-RC- 1 125-BB1, 12-RC-1 125-BBl-1 ,SI-ACC-CL1,7N, 10.126,0 436, 12-RC-1 125-BB1, 12-RC-1 125-BB1-2,SI-ACC-CL1,7N, 10.126,0 437, 12-RC- 1 125-BB1, 12-RC- 1 125-BB1-3,SI-ACC-CL1,7N, 10.126,0 438,12-RC- 1 125-BB1, 12-RC-1 125-BB1-4,SI-ACC-CL1,7N, 10. 126,0 439,12-RC-1 125-BB1 12-RC-1 125-BB1-5,SI-ACC-CL1,7N,10. 126,0 440, 12-RC-1 125-BB1 ,12-RC-1 125-BB1-6,SI-ACC-CL1,7N, 10.126,0 441 ,12-RC-1125-BB1, 12-RC-1 125-BB1-7,SI-ACC-CL1,7N,10. 126,0 442,12-RC-1 125-BB1, 12-RC-1 125-BB1-8,SI-ACC-CL1,7N,10. 126,0 443,12-RC-1125-BB1, 12-RC-1125-BB1-9,SI-ACC-CL1,7N,10. 126,0 444,12-RC-1 125-BB1, 12-RC-1 125-BB1-10,SI-ACC-CL1,7N,10. 126,0 445, 12-RC- 1 125-BB1, 12-RC- 1 125-BBl- 1 1,SI-ACC-CL1,7N, 10.126,0 446,12-RC-1125-BB1, 12-RC-1125-BB1-12,SI-ACC-CL1,7N,10.126,0 447,12-RC-1 125-BB1 12-RC-1 125-BBl-13,SI-ACC-CL1,7N,10. 126,0 448, 12-RC- 1212-BB1, 12-RC-1212-BB1-1,RHR-Suction,7E, 10.126,0 449, 12-RC- 1212-BB1, 12-RC-1212-BB1-2,RHR-Suction,7A, 10.126,0 450,12-RC- 1212-BB1, 12-RC-1212-BB1-3,RRHR-Suction,7A,10.126,0 451,12-RC-1212-BB1 12-RC-1212-BB1-4,RHR-Suction,7A,10. 126,0 452, 12-RC- 1212-BB1, 12-RC-1212-BB1-5,RHR-Suction,7A, 10.126,0 453,12-RC-1212-BB1, 12-RC-1212-BB1-6,RHR-Suction,7A,10. 126,0 454, 12-RC- 1212-BB1, 12-RC-1212-BB1-7,RHR-Suction,7A, 10.126,0 Saturday 14 th March, 2015, 07:39 83 corresponding: keeejLastpegs.coni

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 455,12-RC- 1212-BB1, 12-RC-1212-BB1-8,RHR-Suction,7A, 10.126,0 456,12-RC-1221-BB1, 12-RC-1221-BBl-1 ,SI-ACC-CL2,7N,10. 126,0 457, 12-RC-1221-BB1, 12-RC-1221-BB1-2,SI-ACC-CL2,7N, 10.126,0 458, 12-RC- 1221-BB1, 12-RC-1221-BB1-3,SI-ACC-CL2,7N, 10.126,0 459,12-RC-1221-BB1, 12-RC-1221-BB1-4,SI-ACC-CL2,7N,10. 126,0 460, 12-RC- 1221-BB1, 12-RC-1221-BB1-5,SI-ACC-CL2,7N, 10.126,0 461 ,12-RC-1221-BB1 12-RC-1221-BB1-6,SI-ACC-CL2,7N,10. 126,0 462,12-RC-1221-BB1, 12-RC-1221-BB1-7,SI-ACC-CL2,7N,10.126,0 463,12-RC-1221-BB1, 12-RC-1221-BB1-8,SI-ACC-CL2,7N, 10.126,0 464,12-RC-1221-BB1, 12-RC-1221-BB1-9,SI-ACC-CL2,7N,10. 126,0 465,12-RC-1221-BB1, 12-RC-1221-BB1-10,SI-ACC-CL2,7N,10.126,0 466,12-RC-1221-BB1, 12-RC-1221-BBl-1 1,SI-ACC-CL2,7N,10.126,0 467,12-RC-1221-BB1 12-RC-1221-BBl-12,SI-ACC-CL2,7N,10. 126,0 468,12-RC-1221-BB1, 12-RC-1221-BBl-13,SI-ACC-CL2,7N,10. 126,0 469, 12-RC- 1221-BB1, 12-RC- 1221-BB1-14,SI-ACC-CL2,7N, 10. 126,0 470,12-RC-1312-BB1, 12-RC-1312-BB1-1,RH,7E, 10.126,0 471,12-RC-1312-BB1, 12-RC-1312-BB1-2,RH,7A, 10.126,0 472,12-RC-1312-BB1, 12-RC-1312-BB1-3,RH,7A,10. 126,0 473,12-RC-1312-BB1, 12-RC-1312-BB1-4,RH,7A,10. 126,0 474,12-RC-1312-BB1, 12-RC-1312-BB1-5,RH,7A, 10.126,0 475,12-RC- 1312-BB1,12-RC-1312-BB1-6,RH,7A, 10.126,0 476,12-RC-1312-BB1, 12-RC-1312-BB1-7,RH,7A,10. 126,0 477,12-RC-1312-BB1 12-RC-1312-BB1-8,RH,7A, 10.126,0 478,12-RC-1312-BB1 12-RC-1312-BB1-9,RH,7E, 10.126,0 479,12-RC-1312-BB1, 12-RC-1312-BBl-10,RH,7E,10. 126,0 480,12-RC-1312-BB1, 12-RC-1312-BBl-1 ,RH,7E, 10.126,0 481, 12-RC- 1322-BB1, 12-RC-1322-BBl- 1,SI-ACC-CL3,7N, 10.126,0 482,12-RC- 1322-BB1, 12-RC-1322-BB1-lA,SI-ACC-CL3,7N, 10.126,0 483,12-RC- 1322-BB1, 12-RC-1322-BB 1-2,SI-ACC-CL3,7N, 10. 126,0 484, 12-RC-1322-BB1, 12-RC-1322-BB1-3,SI-ACC-CL3,7N, 10.126,0 485, 12-RC- 1322-BB1, 12-RC-1322-BB1-4,SI-ACC-CL3,7N, 10.126,0 486,12-RH-1 101-BB1, 12-RH-1 101-BBl-1,RH,7E,10.126,0 487,12-RH-1 101-BB1 ,12-RH-1 101-BB1-2,RH,7E, 10.126,0 488,12-RH-1 101-BB1, 12-RH-1101-BB1-3,RH,7E,10.126,0 489,12-RH-1 101-BB1, 12-RH-1 101-BB1-3A,RH,7E,10. 126,0 490,12-RH-1101-BB1 12-RH-1 101-BB1-4,RH,7E,10. 126,0 491,12-RH-1 101-BB1, 12-RH-1 101-BB1-5,RH,7E, 10.126,0 492,12-RH-1101-BB1 12-RH-1 101-BB1-6,RH,7E, 10.126,0 493,12-RH-1 101-BB1 12-RH-1 101-BB1-7,RH,7E,10. 126,0 494,12-RH-1 101-BB1, 12-RH-1 101-BB1-8,RH,7E, 10.126,0 495,12-RH-1 101-BB1 ,12-RH-1 101-BB1-9,RH,7E, 10.126,0 Saturday 1 4 th March, 2015, 07:39 84 corresponding: keeej Ccost pegs. coni

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 496,12-RH-1 101-BB1 ,12-RH-1101-BBl-10,RH,7E,10. 126,0 497,12-RH-1 101-BB1,12-RH-1 101-BBl-i1,RH,7E, 10.126,0 498,12-RH-1 101-BB1,12-RH-1 101-BBl-12,RH,7E, 10.126,0 499,12-RH-1 101-BB1,12-RH-1 101-BBl-13,RH,7E, 10.126,0 500,12-RH-1 101-BB1 ,12-RH-1101-BBl-14,RH,7E,10. 126,0 501,12-RH-1 101-BB1,12-RH-1 101-BBl-15,RH,7E, 10.126,0 502,12-RH-1 101-BB1 ,12-RH-1101-BBl-16,RH,7E,10. 126,0 503,12-RH-1201-BB1, 12-RH-1201-BB1-1,RH,7E, 10.126,0 504,12-RH-1201-BB1 ,12-RH-1201-BB1-2,RH,7E,10. 126,0 505,12-RH-1201-BB1, 12-RH-1201-BBi-3,RH,7E, 10.126,0 506,12-RH-1201-BBI ,12-RH-1201-BB1-4,RH,7E,10.126,0 507,12-RH-1201-BB1,12-RH-1201-BBi-5,RH,7E, 10.126,0 508,12-RH-1201-BB1 ,12-RH-1201-BB1-6,RH,7E,10. 126,0 509,12-RH-1201-BB1,12-RH-1201-BBl-7,RH,7E,10. 126,0 510, 12-RH-1201-BB1 ,12-RH-1201-BB1-8,RH,7E,10. 126,0 511, 12-RH-1201-BB1, 12-RH-1201-BB1-9,RH,7E, 10.126,0 512,12-RH-1201-BB1,12-RH-1201-BBl-10,RH,7E,10. 126,0 513,12-RH-1201-BB1,12-RH-1201-BB1-11,RH,7E, 10.126,0 514,12-RH-1201-BB1 ,12-RH-1201-BBl-12,RH,7E,10. 126,0 515,12-RH-1201-BB1,12-RH-1201-BBl-13,RH,7E, 10.126,0 516,12-RH-1201-BB1,12-RH-1201-BB1-14,RH,7E,10. 126,0 517,12-RH-1201-BB1,12-RH-1201-BBl-15,RH,7E, 10.126,0 518,12-RH-1201-BB1 ,12-RH-1201-BB1-16,RH,7E,10. 126,0 519,12-RH-1201-BB1,12-RH-1201-BBl-17,RH,7E, 10.126,0 520,12-RH-1301-BB1 ,12-RH-1301-BB1-1,RH,7E,10. 126,0 521, 12-RH-1301-BB1, 12-RH-1301-BB1-2,RH,7E,10.126,0 522,12-RH-1301-BB1 ,12-RH-1301-BB1-3,RH,7E,10.126,0 523,12-RH-1301-BB1,12-RH-1301-BB1-4,RH,7E,10. 126,0 524,12-RH-1301-BB1,12-RH-1301-BB1-5,RH,7E, 10.126,0 525,12-RH-1301-BB1 ,12-RH-1301-BB1-5A,RH,7E,10.126,0 526,12-RH-1301-BB1,12-RH-1301-BB1-6,RH,7E, 10.126,0 527, 12-RH-1301-BB1 ,12-RH-1301-BB1-7,RH,7E, 10.126,0 528,12-RH-1301-BB1,12-RH-1301-BB1-8,RH,7E,10.126,0 529,12-RH-1301-BB1 ,12-RH-1301-BB1-9,RH,7E, 10.126,0 530, 12-RH-1301-BB1,12-RH-1301-BBl-10,RH,7E, 10.126,0 531,12-SI-1 125-BB1 ,12-SI-1125-BBl-1,SI-ACC-CL1,70,10.126,0 532,12-SI-I 125-BBI ,12-SI-1 125-BB1-2,SI-ACC-CL1,70,10.126,0 533,12-SI-1 125-BB1, 12-SI-1 125-BB1-3,SI-ACC-CL1,70,10.126,0 534,12-SI-1 125-BB1 ,12-SI-1125-BBi-4,SI-ACC-CLI,70,10.126,0 535, 12-SI-1218-BB1,12-SI-1218-BBl-1,SI-ACC-CL2,70,10.126,0 536,12-SI-1218-BB1 ,12-SI-1218-BB1-2,SI-ACC-CL2,70,10.126,0 Saturday 1 4 th March, 2015, 07:39 85 corresponding: keeejOctstpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 537,12-SI-1218-BB1,12-SI-1218-BB1-3,SI-ACC-CL2,70,10.126,0 538, 12-SI-1218-BB1 ,12-SI-1218-BB1-4,SI-ACC-CL2,70,10.126,0 539,12-SI-1315-BB1 ,12-SI-1315-BB1-1 ,SI-ACC-CL4,70,10.126,0 540,12-SI-1315-BB1,12-SI-1315-BB1-2,SI-ACC-CL4,70,10.126,0 541 ,12-SI-1315-BB1 ,12-SI-1315-BB1-3,SI-ACC-CL4,70,10.126,0 542,12-SI-1315-BB1,12-SI-1315-BB1-4,SI-ACC-CL4,70,10.126,0 543,12-SI-1315-BB1 12-SI-1315-BB1-5,SI-ACC-CL1,70,10.126,0 544,12-SI-1315-BB1 ,12-SI-1315-BB1-6,SI-ACC-CL4,70,10.126,0 545,12-SI-1315-BB1,12-SI-1315-BB1-7,SI-ACC-CL4,70,10.126,0 546,12-SI-1315-BB1,12-SI-1315-BB1-8,SI-ACC-CL4,7D,10. 126,0 547, 12-SI-1315-BB1,12-SI-1315-BB1-9,SI-ACC-CL4,7D,10.126,0 548,12-SI-1315-BB1,12-SI-1315-BBl-10,SI-ACC-CL4,7D,10.126,0 549,27.5-1.C-1103-NSS - LOOP 1,27.5-RC-1103-NSS-4,SI-ACC-CL1,7N,10.126,0 550,27.5-RC-1203-NSS - LOOP 2,27.5-RC-1203-NSS-3,SI-ACC-CL2,7N, 10.126,0 551,27.5-RC-1303-NSS - LOOP 3,27.5-RC-1303-NSS-3,SI-ACC-CL3,7N,10.126,0 552,29-R.C- 1101-NSS - LOOP 1,29-RC-1101-NSS-3,RHR-Suction,7E, 10.126,0 553,29-RC-1201-NSS - LOOP 2,29-RC-1201-NSS-3,RC,7E,10.126,0 554,29-RC-1301-NSS - LOOP 3,29-RC-1301-NSS-3,RC,7E,10.126,0 555,16-RC-1412-NSS,16-RC-1412-NSS-1,Pressurizer Surge Line,4B, 12.814,12.814 556, 16-RC-1412-NSS,16-RC-1412-NSS-3,Pressurizer Surge Line,4B,12.814,0 557,16-RC-1412-NSS, 16-R.C-1412-NSS-4,Pressurizer Surge Line,4B,12.814,0 558,16-RC-1412-NSS, 16-RC-1412-NSS-5,Pressurizer Surge Line,4B, 12.814,0 559,16-RC-1412-NSS,16-RC-1412-NSS-6,Pressurizer Surge Line,4B,12.814,0 560,16-RC-1412-NSS,16-RC-1412-NSS-7,Pressurizer Surge Line,4B,12.814,0 561,16-RC-1412-NSS,16-RC-1412-NSS-8,Pressurizer Surge Line,4B,12.814,0 562,16-RC-1412-NSS,16-RC-1412-NSS-9,Pressurizer Surge Line,4C,12.814,0 563,16-RC-1412-NSS,16-RC-1412-NSS-PRZ-1-N1-SE,Pressurizer Surge Line,4A

,12.814,0 564,29-RC-1401-NSS - LOOP 4,29-1RC-1401-NSS-2,Pressurizer Surge Line,4C

,12.814,0 565,27.5-RC-1103-NSS - LOOP 1,27.5-P.C-1103-NSS-1,RC Cold Leg 1,3C

,27.5,19.4606 566,27.5-RC-1103-NSS - LOOP 1,27.5-RC-1103-NSS-6,RC Cold Leg 1,3C

,27.5,19.5657 567,27.5-RC-1103-NSS - LOOP 1,27.5-RC-1103-NSS-7,RC Cold Leg 1,3C

,27.5,21.0532 568,27.5-RC-1103-NSS - LOOP 1,27.5-RC-1103-NSS-RPV1-N2ASE,RC Cold Leg 1,3 A,27.5,22.047 569,27.5-RC-1203-NSS - LOOP 2,27.5-RC-1203-NSS-1,1.C Cold Leg 2,3C,27.5,0 570,27.5-RC-1203-NSS - LOOP 2,27.5-RC-1203-NSS-4,RC Cold Leg 2,3C,27.5,0 571,27.5-RC-1203-NSS - LOOP 2,27.5-RC-1203-NSS-5,RC Cold Leg 2,3C,27.5,0 Saturdky 14th March, 2015, 07:39 86 corresponding: keeej(Astpegs.com

NOC-AE-1 5003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 572,27.5-RC-1203-NSS - LOOP 2,27.5-RC-1203-NSS-RPV1-N2BSE,RC Cold Leg 2,3 A,27.5,0 573,27.5-RC-1303-NSS - LOOP 3,27.5-RC-1303-NSS-1,RC Cold Leg 3,3C,27.5,0 574,27.5-RC-1303-NSS - LOOP 3,27.5-RC-1303-NSS-5,RC Cold Leg 3,3C,27.5,0 575,27.5-RC-1303-NSS - LOOP 3,27.5-RC-1303-NSS-6,RC Cold Leg 3,3C,27.5,0 576,27.5-RC-1303-NSS - LOOP 3,27.5-RC-1303-NSS-RPV1-N2CSE,RC Cold Leg 3,3 A,27.5,0 577,27.5-RC-1403-NSS - LOOP 4,27.5-RC-1403-NSS-1,RC Cold Leg 4,3C,27.5,0 578,27.5-RC-1403-NSS - LOOP 4,27.5-RC-1403-NSS-5,RC Cold Leg 4,3C,27.5,0 579,27.5-RC-1403-NSS - LOOP 4,27.5-RC-1403-NSS-6,RC Cold Leg 4,3C,27.5,0 580,27.5-RC-1403-NSS - LOOP 4,27.5-RC-1403-NSS-RPV1-N2DSE,RC Cold Leg 4,3 A,27.5,0 581,29-RC-1101-NSS - LOOP 1,29-RC-1101-NSS-1,RC-Hot Leg 1,1B,29,13.9236 582,29-RC-1101-NSS - LOOP 1,29-RC-1101-NSS-4,RC-Hot Leg 1,1B,29,13.9411 583,29-RC-1101-NSS - LOOP 1,29-RC-1101-NSS-5.1,RC-Hot Leg 1,1B,29,14.3682 584,29-RC-1101-NSS - LOOP 1,29-RC-1101-NSS-RPV1-N1ASE,RC-Hot Leg 1,1A

,29,14.404 585,29-RC-1101-NSS - LOOP 1,29-RC-1101-NSS-RSG-1A-IN-SE,RC-Hot Leg 1,2,29,14.4278 586,29-RC-1201-NSS - LOOP 2,29-RC-1201-NSS-1,RC-Hot Leg 2,1B,29,14.4279 587,29-RC-1201-NSS - LOOP 2,29-RC-1201-NSS-4,RC-Hot Leg 2,1B,29,14.4336 588,29-RC-1201-NSS - LOOP 2,29-RC-1201-NSS-5.1,RC-Hot Leg 2,1B,29,14.5424 589,29-RC-1201-NSS - LOOP 2,29-RC-1201-RPV1-N1BSE,RC-Hot Leg 2,1A

,29,15.0515 590,29-RC-1201-NSS - LOOP 2,29-RC-1201-RSG-1B-IN-SE,RC-Hot Leg 2,2,29,15.0866 591,29-RC-1301-NSS - LOOP 3,29-RC-1301-NSS-1,RC-Hot Leg 3,1B,29,15.2938 592,29-RC-1301-NSS - LOOP 3,29-RC-1301-NSS-4,RC-Hot Leg 3,1B,29,15.4956 593,29-RC-1301-NSS - LOOP 3,29-RC-1301-NSS-5.1,RC-Hot Leg 3,1B,29,0 594,29-RC-1301-NSS - LOOP 3,29-RC-1301-RPV1-N1CSE,RC-Hot Leg 3,1A,29,0 595,29-RC-1301-NSS - LOOP 3,29-RC-1301-RSG-1C-IN-SE,RC-Hot Leg 3,2,29,0 596,29-RC-1401-NSS - LOOP 4,29-RC-1401-NSS-1,RC-Hot Leg 4,1B,29,0 597,29-RC-1401-NSS - LOOP 4,29-RC-1401-NSS-3,RC-Hot Leg 4,1C,29,0 598,29-RC-1401-NSS - LOOP 4,29-RC-1401-NSS-4.1,RC-Hot Leg 4,1B,29,0 599,29-RC-1401-NSS - LOOP 4,29-RC-1401-NSS-RPVI-N1DSE,RC-Hot Leg 4,1A

,29,0 600,29-RC-1401-NSS - LOOP 4,29-RC-1401-NSS-RSG-1D-IN-SE,RC-Hot Leg 4,2,29,0 601,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-1.1,RC Cold Leg 1,3D,31,19.6171 602,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-2,RC Cold Leg 1,3D,31,20.2358 603,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-3,RC Cold Leg 1,3D,31,20.35 604,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-4,RC Cold Leg 1,3D,31,21.1162 Saturday 1 4 th March, 2015, 07:39 87 corresponding: keeej9(stpegs.com

NOC-AE-15003220 Attachment 7 STPNOC RoverD: Risk over Deterministic GSI-191 Assessment 88 pages 605,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-8,RC Cold Leg 1,3D,31,21.2781 606,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-9,RC Cold Leg 1,3D,31,22.174 607,31-RC-1102-NSS - LOOP 1,31-RC-1102-NSS-RSG-1A-ON-SE,RC Cold Leg 1,3B

,31,23.169 608,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-1.1,RC Cold Leg 2,3D,31,25.3351 609,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-2,RC Cold Leg 2,3D,31,16.4079 610,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-3,RC Cold Leg 2,3D,31,16.7765 611,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-4,RC Cold Leg 2,3D,31,16.9282 612,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-8,RC Cold Leg 2,3D,31,16.9813 613,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-9,RC Cold Leg 2,3D,31,17.0714 614,31-RC-1202-NSS - LOOP 2,31-RC-1202-NSS-RSG-1B-ON-SE,RC Cold Leg 2,3B

,31,17.2001 615,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-1.1,RC Cold Leg 3,3D,31,17.2398 616,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-2,RC Cold Leg 3,3D,31,17.3454 617,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-3,RC Cold Leg 3,3D,31,17.3737 618,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-4,RC Cold Leg 3,3D,31,17.6362 619,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-8,RC Cold Leg 3,3D,31,17.8428 620,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-9,RC Cold Leg 3,3D,31,17.9194 621,31-RC-1302-NSS - LOOP 3,31-RC-1302-NSS-RSG-1C-ON-SE,RC Cold Leg 3,3B

,31,18.1077 622,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-1.1,RC Cold Leg 4,3D,31,18.1367 623,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-2,RC Cold Leg 4,3D,31,18.1794 624,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-3,RC Cold Leg 4,3D,31,18.1976 625,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-4,RC Cold Leg 4,3D,31,18.3113 626,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-8,RC Cold Leg 4,3D,31,18.3429 627,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-9,RC Cold Leg 4,3D,31,19.235 628,31-RC-1402-NSS - LOOP 4,31-RC-1402-NSS-RSG-1D-ON-SE,RC Cold Leg 4,3B

,31,19.2473 Saturday 14t' March, 2015, 07:39 88 corresponding: keeej Ast pegs. coin

NOC-AE-1 5003220 Attachment 8 Attachment 8 Regulatory Commitments

NOC-AE-1 5003220 Attachment 8 Page 1 of 1 Commitments The following table identifies the action committed to by STPNOC in this document. Any statements in this document with the exception of those in the table below are provided for information purposes and are not considered commitments.

Commitment CR Due STPNOC will submit a 11-4249-289 June 2015 (not part of supplement to the pilot commitment) licensing application that incorporates RoverD.

NOC-AE-1 5003220 Attachment 9 Attachment 9 Definitions and Acronyms

NOC-AE-15003220 Attachment 9 Page 1 of 2 Definitions and Acronyms ANS American Nuclear Society ECCS Emergency Core Cooling ARL Alden Research Laboratory System ASME American Society of ECWS Essential Cooling Water Mechanical Engineers System (also ECW)

BA Boric Acid EOF Emergency Operations BAP Boric Acid Precipitation Facility BC Branch Connection EOP Emergency Operating BEP Best Efficiency Point Procedure(s)

B-F Bimetallic Welds EPRI Electric Power Research B-J Single Metal Welds Institute BWR Boiling Water Reactor EQ Equipment Qualification CAD Computer Aided Design ESF Engineered Safety Feature CASA Containment Accident FA Fuel Assembly(s)

Stochastic Analysis, also a FHB Fuel Handling Building short name for the CASA GDC General Design Criterion(ia)

Grande computer program GL Generic Letter that uses the analysis GSI Generic Safety Issue methodology HHSI High Head Safety Injection CCDF Complementary Cumulative (ECCS Subsystem)

Distribution Function or HLB Hot Leg Break Conditional Core Damage HTVL High Temperature Vertical Frequency Loop CCW Component Cooling Water HLSO Hot Leg Switchover CDF Core Damage Frequency ID Inside Diameter CET Core Exit Thermocouple(s) IGSCC Intergranular Stress CHLE Corrosion/Head Loss Corrosion Cracking Experiments ISI In-Service Inspection CHRS Containment Heat Removal LAR License Amendment System Request CLB Cold Leg Break or Current LBB Leak Before Break Licensing Basis LBLOCA Large Break Loss of Coolant CRMP Configuration Risk Accident Management Program LCO Limiting Condition for CS Containment Spray Operability CSHL Clean Strainer Head Loss LDFG Low Density Fiberglass CSS Containment Spray System LERF Large Early Release (same as CS) Frequency CVCS Chemical Volume Control LHS Latin Hypercube Sampling System LHSI Low Head Safety Injection DBA Design Basis Accident (ECCS Subsystem)

DBD Design Basis Document LOCA Loss of Coolant Accident D&C Design and Construction LOOP/LOSP Loss of Off Site Power Defects MAAP Modular Accident Analysis DEGB Double Ended Guillotine Program Break MAB/MEAB Mechanical Auxiliary Building DID Defense in Depth or Mechanical Electrical DM Degradation Mechanism Auxiliary Building ECC Emergency Core Cooling MBLOCA Medium Break Loss of (same as ECCS) Coolant Accident

NOC-AE-1 5003220 Attachment 9 Page 2 of 2 Definitions and Acronyms NIST National Institute of RoverD Risk over Deterministic Standards and Technology Methodology NLHS Non-uniform Latin Hypercube RVWL Reactor Vessel Water Level Sampling RWST Refueling Water Storage NPSH Net Positive Suction Head, Tank (NPSHA - available, NPSHR SBLOCA Small Break Loss of Coolant

- required) Accident NRC Nuclear Regulatory SC Stress Corrosion Commission SI/SIS Safety Injection, Safety NSSS Nuclear Steam Supply Injection System (same as System ECCS)

OBE Operating Basis Earthquake SIR Safety Injection and OD Outer Diameter Recirculation PCI Performance Contracting, SR Surveillance Requirement Inc. SRM Staff Requirements PCT Peak Clad Temperature Memorandum PDF Probability Density Function SSE Safe Shutdown Earthquake PRA Probabilistic Risk STP South Texas Project Assessment STPEGS South Texas Project Electric PWR Pressurized Water Reactor Generating Station PWROG Pressurized Water Reactor STPNOC STP Nuclear Operating Owner's Group Company PWSCC Primary Water Stress TAMU Texas A&M University Corrosion Cracking TF Thermal Fatigue QDPS Qualified Display Processing TGSCC Transgranular Stress System Corrosion Cracking RAI Request for Additional TS Technical Specification(s)

Information TSB Technical Specification RCB Reactor Containment Bases Building TSC Technical Support Center RCFC Reactor Containment Fan TSP Trisodium Phosphate Cooler UFSAR Updated Final Safety RCS Reactor Coolant System Analysis Report RG Regulatory Guide UNM University of New Mexico RHR Residual Heat Removal USI Unresolved Safety Issue RI-ISI Risk-Informed In-Service UT University of Texas (Austin)

Inspection V&V Verification and Validation RMI Reflective Metal Insulation VF Vibration Fatigue RMTS Risk Managed Technical WCAP Westinghouse Commercial Specifications Atomic Power ZOI Zone of Influence