Text

NRR E-mail Capture - South Texas Project Units 1 & 2, Draft Request for Additional Information for Thermal-hydraulic Review for GSI-191
	ML16040A069
Person / Time
Site:	South Texas
Issue date:	02/04/2016
From:	Lisa Regner; Plant Licensing Branch IV
To:	Harrison W; South Texas
References
	MF2400, MF2401
	Download: ML16040A069 (25)
	v • d • e

NRR-PMDAPEm Resource From: Regner, Lisa Sent: Thursday, February 04, 2016 4:08 PM To: Wayne Harrison Cc: Michael Murray; Sterling, Lance (lsterling@STPEGS.COM)

Subject:

DRAFT RAI for Thermal-hydraulic review of STP GSI-191 Attachments: IBMgetContent.docx

Wayne, Attached is the draft thermal-hydraulic RAI. The technical staff is implementing a pilot program where they provide a categorization scheme for each of the questions to help better describe the extent of the staffs concern and level of effort expected to resolve the issue. Details of this categorization are included in the attachment.

You will see that the staff has a number of remaining significant concerns in the T-H area and we are hopeful that the upcoming audit will assist in the efficiency of the resolution of these remaining concerns.

We will discuss these further with you at the public meeting on 2/18, and at the audit, as needed.

Thank you, Lisa Lisa M Regner, Sr. Project Manager, Branch LPLIV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Lisa.Regner@NRC.Gov Office: O8D08 Mail Stop: O8B01 (301) 415-1906 1

Hearing Identifier: NRR_PMDA Email Number: 2647 Mail Envelope Properties (7afc1ee36a4147bfb8818b61285a7a9e)

Subject:

DRAFT RAI for Thermal-hydraulic review of STP GSI-191 Sent Date: 2/4/2016 4:07:55 PM Received Date: 2/4/2016 4:07:00 PM From: Regner, Lisa Created By: Lisa.Regner@nrc.gov Recipients:

"Michael Murray" <mpmurray@STpegs.com>

Tracking Status: None "Sterling, Lance (lsterling@STPEGS.COM)" <lsterling@STPEGS.COM>

Tracking Status: None "Wayne Harrison" <awharrison@STPEGS.COM>

Tracking Status: None Post Office: HQPWMSMRS01.nrc.gov Files Size Date & Time MESSAGE 940 2/4/2016 4:07:00 PM IBMgetContent.docx 52217 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

To facilitate better communication, each of the requests for additional information (RAIs) has been categorized by the U.S. Nuclear Regulatory Commission (NRC) staff. The three categories considered are:

Level of Concern (i.e., How concerned is the NRC staff with the statements in the submittal which generated this RAI?),

Level of Impact (i.e., What is the perceived level of impact of RAI to the approval of the submittal?, and

Level of Effort (i.e., What is the perceived level of work which will be needed to satisfy this RAI?)

Each RAI is assigned a level in each category (1-5) and the scores are combined to generate the following significance table. Further details on each category are provided at the end of this document. The individual levels of each RAI are provided with that RAI below.

Table 1: RAI Summary for STP STNP-RAIs Level of Number of Significance RAIs High 13 Moderate 9 Low 10 ENCLOSURE

Table 2: RAI Categorization Summary for STP SNPB-RAIs RAI Concern Impact Effort Significance 1 2 1 2 High 2 1 1 1 High 3 5 3 4 Low 4 1 1 1 High 5 2 3 3 Moderate 6 2 1 2 High 7 1 1 1 High 8 3 1 3 Low 9 3 1 3 Moderate 10 3 3 3 Low 11 3 3 2 Low 12 3 3 2 Low 13 2 1 1 High 14 3 3 3 Low 15 3 3 3 Low 16 3 1 5 Moderate 17 2 1 1 High 18 2 3 2 Moderate 19 3 3 3 Low 20 3 3 2 Low 21 3 3 3 Low 22 2 3 2 Moderate 23 1 1 1 High 24 1 2 1 High 25 3 2 2 Moderate 26 1 2 2 High 27 1 2 2 High 28 3 2 2 Moderate 29 1 2 2 High 30 3 2 2 Moderate 31 2 2 2 High 32 3 2 3 Moderate

--3--

Level of Significance Definition Concern Points The NRC staff is very concerned as the RAI is focused upon 1 statements which the staff understands, but the staff believes 1 are incorrect.

The NRC staff is concerned as the RAI is focused upon 2 statements which the staff understands, but the staff is skeptical 1 about being correct.

The NRC staff is somewhat concerned as the RAI is focused upon statements which the staff understands and believes are 3 0 correct, but considers the supporting documentation to be inadequate.

The NRC staff is unsure of their concern as the as the RAI is 4 focused upon statements which the staff does not understand, 0 and; therefore clarification is needed.

5 The NRC staff is minimally concerned. 0 Level of Significance Definition Impact Points The RAI could have a very large impact. If it is not resolved, either the submittal will be denied or the approval would be so 1 1 limited that the method described in the submittal may be unusable.

The RAI could have a large impact. If it is not resolved, the 2 approval will be limited such that the submittal would be usable, 1 but significantly limited.

The RAI could have somewhat of an impact. If it is not resolved, 3 the approval will be limited such that the submittal would be 0 usable and only slightly limited.

The impact of the RAI is unknown as it is address information in 4 0 the submittal which the staff does not understand.

The RAI likely has a minimal impact. If it is not resolved, the 5 0 approval would likely not be limited.

--4--

Level of Significance Definition Effort Points The RAI will likely require a very significant level of effort to resolve. Such requests are typically made when important aspects of a specific assertion of the submittal are missing and likely require substantial additional analysis by the submitter or the NRC staff. Additionally, the NRC staff believes that there 1 is a high likelihood of having an additional RAI on the newly 1 submitted information.

Examples: data required for independent verification, need for additional computational runs, need for additional experimental data The RAI will likely require a significant level of effort to resolve.

Such requests are typically made when important aspects of a specific assertion of the submittal are missing and likely require additional analysis by the submitter. Additionally, the NRC staff 2 does not believe that there is a high likelihood of having an 0 additional RAI on the newly submitted information.

Examples: complete justifications of an assertion, detailed summary The RAI will likely require some level of effort to resolve. Such requests including requesting data or information which may not be immediately available, but is likely known or understood by 3 0 the submitter.

Examples: further explanations or details, high level summary The RAI will likely require a small level of effort to resolve.

Such requests include requesting a data or information which is likely to be immediately available, but has not been given.

4 0 Examples: a citation for a reference, a figure or a table of known data The RAI will likely require a minimal level of effort to resolve.

Such requests include requesting an affirmation of a certain 5 position (i.e., yes or no). 0 Examples: a confirmation that a certain procedure is being used To determine an RAIs Overall Significance, sum that RAIs Significance Points from each attribute.

--5--

The following criteria were used for this review:

Criterion Title Criteria Reference The thickness of the cladding oxide and the SE for WCAP-0.1 Clad Oxidation deposits of material on the fuel shall not exceed 16793-NP, 0.050 inches in any fuel region. Revision 2 The process used for accident scenario SRP Section Structured 1.1 identification should be a structured process. 15.0.2 Sub-Process Section III.3c The description of each accident scenario should SRP Section Accident 1.2 provide a complete and accurate description of 15.0.2 Sub-Progression the accident progression. Section III.3c Phenomena The dominant physical phenomena influencing the SRP Section 1.3 Identification outcome of the accident should be correctly 15.0.2 Sub-and Ranking identified and ranked. Section III.3c Initial and The description of each accident scenario should SRP Section 1.4 Boundary provide complete and accurate description of the 15.0.2 Sub-Conditions plant initial and boundary conditions. Section III.3c The documentation should be reviewed to SRP Section determine if (i) all documentation listed in Section 15.0.2 Sub-II.1 above has been provided [the evaluation Section III.3a model, the accident scenario identification process, the code assessment, the uncertainty Necessary analysis, a theory manual, a user manual, and the 2.1 Documentation quality assurance program], (ii) the evaluation model overview provides an accurate roadmap of the evaluation model documentation, (iii) all documentation is accurate, complete, and consistent and, (iv) all symbols and nomenclature have been defined and consistently used.

The theory manual should be a self-contained SRP Section document that describes the field equations, 15.0.2 Sub-closure relationships, numerical solution Section III.3a 2.2 Theory Manual techniques, and simplifications and approximations (including limitations) inherent in the chosen field equations and numerical methods.

The theory manual should identify the pedigree or SRP Section Closure origin of closure relationships used in the code 15.0.2 Sub-2.3 Relationships and the limits of applicability for all models in the Section III.3a code.

--6--

The user manual should provide guidance for SRP Section 2.4 User Manual selecting or calculating all input parameters and 15.0.2 Sub-code options. Section III.3a Options for The guidance in the [user] manual should specify SRP Section 2.5 Licensing the required and acceptable code options for the 15.0.2 Sub-Calculations specific licensing calculations. Section III.3a The required input settings are hardwired into the SRP Section input processor so that the code stops with an 15.0.2 Sub-error message if the required input is not provided Section III.3a 2.6 Required Input or if the input is not within an acceptable range of values or that administrative controls (an independent reviewer QA check) are in place that accomplish the same purpose.

Accident Computer codes that are used for multiple SRP Section 2.7 Specific accidents and transients should include guidelines 15.0.2 Sub-Guidelines that are specific to each transient or accident.Section III.3a Previously It should be determined if the mathematical SRP Section Reviewed and modeling and computer codes used to analyze 15.0.2 Sub-3.1 Accepted the transient or accident should be been Section III.3b Codes and previously reviewed and accepted.

Models The physical modeling described in the theory SRP Section manual and contained in the mathematical models 15.0.2 Sub-Physical 3.2 should be adequate to calculate the physical Section III.3b Modeling phenomena influencing the accident scenario for which the code is used.

The field equations of the evaluation model should SRP Section Field 3.3 be adequate to describe the set of physical 15.0.2 Sub-Equations phenomena that occur in the accident. Section III.3b The range of validity of the closure relationships SRP Section Validation of should be specified and should be adequate to 15.0.2 Sub-3.4 the Closure cover the range of conditions encountered in the Section III.3b Relationships accident scenario.

Simplifying and The simplifying assumptions and assumptions SRP Section 3.5 Averaging used in the averaging procedure should be valid 15.0.2 Sub-Assumptions for the accident scenario under consideration. Section III.3b The level of detail in the model should be SRP Section Level of Detail equivalent to or greater than the level of detail 15.0.2 Sub-3.6 in the Model required to specify the answer to the problem of Section III.3b interest.

The equations and derivations should be correct SRP Section Equations and 3.7 15.0.2 Sub-Derivations Section III.3b

--7--

Similarity The similarity criteria and scaling rationales SRP Section should be based on the important phenomena 15.0.2 Sub-Criteria and 3.8 and processes identified by the accident scenario Section III.3b Scaling identification process and appropriate scaling Rationale analyses.

Scaling analyses should be conducted to ensure SRP Section Scaling 3.9 that the data and the models will be applicable to 15.0.2 Sub-Analysis the full scale analysis of the plant transient. Section III.3b Single Version All assessment cases should be performed with a SRP Section of the single version of the evaluation model. 15.0.2 Sub-4.1 Section III.3d Evaluation Model Integral test assessments must properly validate SRP Section the predictions of the evaluation model for the full 15.0.2 Sub-Validation of size plant accident scenarios. This validation Section III.3d 4.2 the Evaluation should cover all of the important code models and Model the full range of conditions encountered in the accident scenarios.

All code closure relationships based in part on SRP Section experimental data or more detailed calculations 15.0.2 Sub-Range of should be assessed over the full range of Section III.3d 4.3 Assessment conditions encountered in the accident scenario by means of comparison to separate effects test data.

The numerical solution should conserve all SRP Section Numerical 4.4 important quantities. 15.0.2 Sub-Solution Section III.3d All code options that are to be used in the SRP Section 4.5 Code Tuning accident simulation should be appropriate and 15.0.2 Sub-should not be used merely for code tuning. Section III.3d

--8--

The reviewers should ensure that the SRP Section documentation contains comparisons of all 15.0.2 Sub-Compensating 4.6 important experimental measurements with the Section III.3d Errors code predictions in order to expose possible cases of compensating errors.

Assessments should be performed where SRP Section applicable [specific test cases for LOCA to meet 15.0.2 Sub-the requirements of Appendix K to 10 CFR Part Section III.3d 50 and TMI action items for PWR small-break LOCA].

Appropriate sensitivity studies shall be performed Appendix K to for each evaluation model, to evaluate the effect 10 CFR Part 50 on the calculated results of variations in noding, Specific Test 4.7 phenomena assumed in the calculation to Cases predominate, including pump operation or locking, and values of parameters over their applicable ranges. For items to which results are shown to be sensitive, the choices made shall be justified.

A detailed analysis shall be performed of the thermal-mechanical conditions in the reactor TMI action items vessel during recovery from small breaks with an for PWR extended loss of all feedwater.

Published literature should be referred to for SRP Section Assessment 4.8 sources of assessment data for specific 15.0.2 Sub-Data phenomena, accident scenarios, and plant types.Section III.3d Important The accident scenario identification process SRP Section 5.1 Sources of should be used in identifying the important 15.0.2 Sub-Uncertainty sources of uncertainty. Section III.3e The method for calculating uncertainty should SRP Section contain all important sources of uncertainty and 15.0.2 Sub-that a sample uncertainty calculation for a Section III.3e Code 5.2 prototypical plant gives a reasonable estimate of Uncertainty the calculation uncertainty. The reviewers should confirm that sources of code uncertainty have been addressed.

Sources of calculation uncertainties should be SRP Section addressed, including uncertainties in plant model 15.0.2 Sub-Calculation 5.3 input parameters for plant operating conditions Section III.3e Uncertainty (e.g., accident initial conditions, set points, and boundary conditions).

The uncertainties in the experimental data base SRP Section Experimental 5.4 should be addressed. 15.0.2 Sub-Uncertainty Section III.3e

--9--

For separate effects tests and integral effects SRP Section Calculated and tests, the differences between calculated results 15.0.2 Sub-5.5 Predicted and experimental data for important phenomena Section III.3e Results should be quantified for bias and deviation.

Data sets and correlations with experimental SRP Section Data with uncertainties that are too large when compared to 15.0.2 Sub-5.6 Large the requirements for evaluation model Section III.3e Uncertainties assessment should not be used.

When the code is used in a licensing calculation, SRP Section Uncertainties the combined code and application uncertainty 15.0.2 Sub-5.7 and Design should be less than the design margin for the Section III.3e Margin safety parameter of interest in the calculation.

Appendix B The evaluation model should be maintained under SRP Section Quality a quality assurance program that meets the 15.0.2 Sub-6.1 requirements of Appendix B to 10 CFR Part 50.Section III.3f Assurance Program The quality assurance program documentation SRP Section Quality should include procedures that address all of 15.0.2 Sub-6.2 Assurance these areas [design control, document control, Section III.3f Documentation software configuration control and testing, and corrective actions].

Independent peer reviews should be performed at SRP Section Independent 6.3 key steps in the evaluation model development 15.0.2 Sub-Peer Review process. Section III.3f

1. RAI-SNPB-01 Cladding Oxide Demonstrate that the thickness of the cladding oxide and the deposits of material on the fuel do not exceed 0.050 inches in any fuel region.

Criterion 0.1 Level of Level of Level of 2 1 2 Concern Impact Effort Overall High Significance

2. RAI-SNPB-02 Accident Scenario Progression Provide a description of the accident progression of the four accident scenarios being simulated using the LTCC EM. This description should start at the initiation of the break, define each phase, and the important phenomena occurring in that phase in the various locations of the RCS (e.g., core, reactor vessel, steam generators - both primary and secondary side, loops, pressurizer, pumps, containment).

Criterion 1.2 Level of Level of Level of 1 1 1 Concern Impact Effort Overall High Significance

3. RAI-SNPB-03 Clarification on Core Bypass Blockage During the audit, STP was considering performing the long term core cooling analysis with the core bypass open to allow flow in the axial direction. Does STP intend to make this change and allow flow axially through the bypass or will STP continue with the bypass completely blocked? If STP is crediting the use of the bypass, they should provide analysis to demonstrate that the bypass will not block during the scenarios. If they are not crediting the bypass, they should inform the NRC that they plan to continue with their current model.

Criterion 1.3 Level of Level of Level of 5 3 4 Concern Impact Effort Overall Low Significance

4. RAI-SNPB-04 Describe important phenomena Provide a description of the important phenomena being modeled in RELAP5-3D for of each of the four accident scenarios being simulated. These phenomena should include those important to obtaining the correct initial conditions for the long-term phase, and those phenomena important during the long-term phase. Additionally, this description should include the range of the system parameters over which the phenomena occur.

Criterion 1.3 Level of Level of Level of 1 1 1 Concern Impact Effort Overall High Significance

5. RAI-SNPB-05 Debris at grid spacers Describe how the LTCC EM accounts for crud and potential blockages at spacer grids.

Criterion 1.3 Level of Level of Level of 2 3 3 Concern Impact Effort Overall Moderate Significance

6. RAI-SNPB-06 Initial and Boundary Conditions for each Accident Scenario Demonstrate that the initial and boundary conditions for each accident scenario are appropriate for the given simulation. This demonstration should focus on the simulations performed under the Appendix B QAP. Provide a discussion of the confirmation of the initial and boundary conditions and describe how it was determined that these conditions reflect the conditions in the plant. Provide a discussion on the treatment of uncertainties. Additionally, provide any appropriate references.

If this demonstration relies on comparisons with results from other computer codes provide (1) a description of the code, (2) confirmation that the code has been approved by the NRC, (3) a summary of the simulations the code has been approved to analyze, and (4) an analysis addressing each boundary and initial and boundary condition and how a deviation in that condition would be reflected in the code comparison.

Criterion 1.4 Level of Level of Level of 2 1 2 Concern Impact Effort Overall High Significance

7. RAI-SNPB-07 Initial and Boundary Conditions for the Long-Term Phase Demonstrate that the initial and boundary conditions for each accident scenario at the beginning of the long-term phase are consistent with those conditions which are expected.

This demonstration should analyze the RELAP5-3D calculations for the conditions at the beginning of reflood and show that those calculations are reasonable compared with known behavior. This analysis should include comparison between the conditions calculated by RELAP5-3D and the current large and small break LOCA safety analyses.

Criterion 1.4 Level of Level of Level of 1 1 1 Concern Impact Effort Overall High Significance

8. RAI-SNPB-08 How are the phenomena modeled Summarize how the important phenomena are being modeled in the LTCC EM. This discussion should provide the phenomena and a summary of how it is being modeled (e.g.,

through the field equations, by an identified closure relationship).

Criterion 2.2 Level of Level of Level of 3 3 3 Concern Impact Effort Overall Low Significance

9. RAI-SNPB-09 Reference and limits of closure relationships Demonstrate that each closure relationship is associated with an appropriate reference providing its limits of applicability.

Criterion 2.3 Level of Level of Level of 3 1 3 Concern Impact Effort Overall Moderate Significance

10. RAI-SNPB-10 User Manual Provide the user manual and/or similar guidance for analysts performing simulations using the LTCC EM.

Criterion 2.4 Level of Level of Level of 3 3 3 Concern Impact Effort Overall Low Significance

11. RAI-SNPB-11 Modeling of Important Phenomena Provide a summary of the important phenomena and demonstrate the LTCC EM is able to adequately model those phenomena.

Criterion 3.2 Level of Level of Level of 3 3 2 Concern Impact Effort Overall Low Significance

12. RAI-SNPB-12 Field Equations Define and provide a summary of the field equations for the LTCC EM. This should include identification of the of the conservation equation (e.g., mass, momentum) and the number of dimensions of the equation. For portions of the RCS model that change in nodalization (e.g.,

1-D to 3-D) a separate description may be necessary. Additionally, demonstrate that these equations are able to model the necessary phenomena.

Criterion 3.3 Level of Level of Level of 3 3 2 Concern Impact Effort Overall Low Significance

13. RAI-SNPB-13 Validation of closure relationships For the closure relationships identified, provide appropriate validation for the use of this relationship over its expected application domain. This validation should include comparisons to separate effects tests and/or integral test data and appropriately address the models uncertainty. Where appropriate, discuss any similarity criteria, scaling rationale, assumptions, simplifications, and/or compensating errors.

Criterion 3.4, 3.8, 3.9, 4.3,4.6, 5.2, 5.4, 5.5, 5.6 Level of Level of Level of 2 1 1 Concern Impact Effort Overall High Significance

14. RAI-SNPB-14 Simplifying and averaging Provide a summary of the key simplifying and averaging assumptions used in the generation of the mathematical models used in the LTCC EM and demonstrate that they are appropriate for the accident scenarios being modeled.

Criterion 3.5 Level of Level of Level of 3 3 3 Concern Impact Effort Overall Low Significance

15. RAI-SNPB-15 Level of detail Confirm that the level of detail (e.g., phenomena modeled, initial and boundary conditions, overall assumptions) is consistent between STPs LOCA licensing basis analysis and the simulations performed using RELAP5-3D.

Criterion 3.6 Level of Level of Level of 3 3 3 Concern Impact Effort Overall Low Significance

16. RAI-SNPB-16 Single version of the evaluation model Confirm that a single version of the evaluation model was used during the simulations of the given accident scenarios. This includes confirming that the code version was frozen and the manner for calculating or obtaining inputs did not change.

Criterion 4.1 Level of Level of Level of 3 1 5 Concern Impact Effort Overall Moderate Significance

17. RAI-SNPB-17 Validation of the evaluation model Provide appropriate validation demonstrating that the LTCC EM will result in a reasonable prediction of the important figures of merit for the accident scenarios considered.

Demonstrate that the validation covers the range of the accident scenarios used in the LTCC EM. This validation should include comparisons to integral test data and appropriately address the models uncertainty. Where appropriate, discuss any similarity criteria, scaling rationale, assumptions, simplifications, and/or compensating errors.

Criterion 4.2, 3.8, 3.9, 4.3,4.6, 5.2, 5.4, 5.5, 5.6 Level of Level of Level of 2 1 1 Concern Impact Effort Overall High Significance

18. RAI-SNPB-18 Mesh size sensitivity Demonstrate that the LTCC results are independent of mesh size for the accident scenarios under consideration.

Criterion 4.7 Level of Level of Level of 2 3 2 Concern Impact Effort Overall Moderate Significance

19. RAI-SNPB-19 Initial Test Cases Provide a summary of the assessment cases performed in order to demonstrate that RELAP5-3D has been installed and is being used appropriately.

Criterion 4.7 Level of Level of Level of 3 3 3 Concern Impact Effort Overall Low Significance

20. RAI-SNPB-20 Specific sensitivity studies During the audit, the NRC staff identified a number of sensitivity studies that would be important for the review of the proposed long term core cooling evaluation methodology. STP should perform the following sensitivity studies and submit plots of the relevant figures of merit and important timings for long term core cooling analysis:

a) Appendix K decay heat load with single worst failure and steam generator tube plugging b) Axial power shape c) Small break sensitivity study with appropriate break size resolution Criterion 4.7 Level of Level of Level of 3 3 2 Concern Impact Effort Overall Low Significance

21. RAI-SNPB-21 Important Sources of Uncertainty Demonstrate that the important sources of uncertainty are appropriately accounted for in the LTCC EM.

Criterion 5.3, 5.2 Level of Level of Level of 3 3 3 Concern Impact Effort Overall Low Significance

22. RAI-SNPB-22 Uncertainness and design margin Provide a discussion on the impact of the uncertainties considered on the important figures of merit (e.g., PCT) for each of the accident scenarios and the margin to the design limit.

Criterion 5.7 Level of Level of Level of 2 3 2 Concern Impact Effort Overall Moderate Significance

23. RAI-SNPB-23 Evaluation Model in an Appendix B QAP To address GL 2004-02, STP is demonstrate its compliance with 10 CFR 50.46 (b)(5), Long term core cooling, including the impact of debris, using the following two step approach:

(1) The hot leg large break, hot leg medium break, hot leg small break, and cold leg small break will be demonstrated to be in compliance with 10 CFR 50.46 (b)(5) by ensuring that the long term core temperature does not exceed 800° F assuming a fully blocked core. This is demonstrated by using deterministic analysis performed with RELAP5-D (2) The cold leg large break and cold leg medium break will rely on a risk informed approach.

The hot leg large break, hot leg medium break, hot leg small break, and cold leg small break analyses are used to demonstrate compliance with 10 CFR 50.46 (b)(5). Therefore certain design control measures are required, as specified in 10 CFR 50, Appendix B (III):

Design control measures shall be applied to items such as the following: reactor physics, stress, thermal, hydraulic, and accident analyses; compatibility of materials; accessibility for inservice inspection, maintenance, and repair; and delineation of acceptance criteria for inspections and tests.

However, it is not apparent that the RELAP5-3D analysis was performed under a QA program satisfying the requirements of Appendix B.

Demonstrate that the RELAP5-3D analysis was performed under a QA program which satisfies the requirements of 10 CFR 50, Appendix B, or provide a similar analysis that was performed under such a program.

Criterion 6.1 Level of Level of Level of 1 1 1 Concern Impact Effort Overall High Significance

24. RAI-SNPB-24 Input Verification Provide details of how STPs QAP controls over the input deck for the LTCC EM. How are the input values verified? What inputs are users given permission to change and how are such changes controlled?

Criterion 6.1 Level of Level of Level of 1 2 1 Concern Impact Effort Overall High Significance

25. RAI-SNPB-25 Proper Convergence How does the QAP ensure the code converged properly? Such indicators commonly include nonphysical state properties and excessive mass error. Demonstrate that if the code did not converge numerically, the analysts would be alerted to the error messages and act appropriately.

Criterion 6.1 Level of Level of Level of 3 2 2 Concern Impact Effort Overall Moderate Significance

26. RAI-SNPB-26 Non-physical results How does the QAP ensure non-physical results were not obtained? Such as liquid over vaper, unphysical oscillations that could be numerically induced, or any other nonphysical results that may lead to erroneous conclusions concerning the codes calculated thermal-hydraulic behavior.

Criterion 6.1 Level of Level of Level of 1 2 2 Concern Impact Effort Overall High Significance

27. RAI-SNPB-27 Realistic results How does the QAP ensure the physical results are realistic? Where the calculated flow regimes and heat transfer modes should be studied to ensure that the code is not assuming unrealistic conditions?

Criterion 6.1 Level of Level of Level of 1 2 2 Concern Impact Effort Overall High Significance

28. RAI-SNPB-28 Boundary conditions as prescribed How does the QAP ensure that the boundary conditions are occurring as prescribed?

Boundary conditions and others that control the direction of the transient (e.g., valves opening, pumps beginning to coast down, or heater rod power turning off) should be checked by the user to ensure that all is happening as expected.

Criterion 6.1 Level of Level of Level of 3 2 2 Concern Impact Effort Overall Moderate Significance

29. RAI-SNPB-29 Thoroughly understood results How does the QAP ensure that every aspect of the calculation is thoroughly understood?

The depressurization rate, various indications of core heatup, drain rate of the system at various locations, liquid holdup, indications of condensation or evaporation, transition from subcooled to two-phase break flow, and other conditions should all be explainable. Also, the results of the user's calculation should be understood from the perspective of previous calculations done on the same or similar facilities.

Criterion 6.1 Level of Level of Level of 1 1 2 Concern Impact Effort Overall High Significance

30. RAI-SNPB-30 Quality assurance program documentation Demonstrate that the documentation for the QAP includes procedures to address all relevant areas including, but not limited to, design control, document control, software configuration control and testing, and corrective actions.

Criterion 6.2 Level of Level of Level of 3 2 2 Concern Impact Effort Overall Moderate Significance

31. RAI-SNPB-31 Independent Peer Review Demonstrate that the QAP used independent peer review in the key steps appropriately. This should include a description of the steps where independent peer review was applied and how independence was defined and obtained.

Criterion 6.2 Level of Level of Level of 2 2 2 Concern Impact Effort Overall High Significance

32. RAI-SNPB-32 Important Sources of Uncertainty Identify the important sources of uncertainty in the LTCC EM Criterion 5.1 Level of Level of Level of 3 2 3 Concern Impact Effort Overall Moderate Significance

NRR-PMDAPEm Resource From: Regner, Lisa Sent: Thursday, February 04, 2016 4:08 PM To: Wayne Harrison Cc: Michael Murray; Sterling, Lance (lsterling@STPEGS.COM)

Subject:

DRAFT RAI for Thermal-hydraulic review of STP GSI-191 Attachments: IBMgetContent.docx

Wayne, Attached is the draft thermal-hydraulic RAI. The technical staff is implementing a pilot program where they provide a categorization scheme for each of the questions to help better describe the extent of the staffs concern and level of effort expected to resolve the issue. Details of this categorization are included in the attachment.

You will see that the staff has a number of remaining significant concerns in the T-H area and we are hopeful that the upcoming audit will assist in the efficiency of the resolution of these remaining concerns.

We will discuss these further with you at the public meeting on 2/18, and at the audit, as needed.

Thank you, Lisa Lisa M Regner, Sr. Project Manager, Branch LPLIV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Lisa.Regner@NRC.Gov Office: O8D08 Mail Stop: O8B01 (301) 415-1906 1

Hearing Identifier: NRR_PMDA Email Number: 2647 Mail Envelope Properties (7afc1ee36a4147bfb8818b61285a7a9e)

Subject:

DRAFT RAI for Thermal-hydraulic review of STP GSI-191 Sent Date: 2/4/2016 4:07:55 PM Received Date: 2/4/2016 4:07:00 PM From: Regner, Lisa Created By: Lisa.Regner@nrc.gov Recipients:

"Michael Murray" <mpmurray@STpegs.com>

Tracking Status: None "Sterling, Lance (lsterling@STPEGS.COM)" <lsterling@STPEGS.COM>

Tracking Status: None "Wayne Harrison" <awharrison@STPEGS.COM>

Tracking Status: None Post Office: HQPWMSMRS01.nrc.gov Files Size Date & Time MESSAGE 940 2/4/2016 4:07:00 PM IBMgetContent.docx 52217 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

To facilitate better communication, each of the requests for additional information (RAIs) has been categorized by the U.S. Nuclear Regulatory Commission (NRC) staff. The three categories considered are:

Level of Concern (i.e., How concerned is the NRC staff with the statements in the submittal which generated this RAI?),

Level of Impact (i.e., What is the perceived level of impact of RAI to the approval of the submittal?, and

Level of Effort (i.e., What is the perceived level of work which will be needed to satisfy this RAI?)