ML16176A148: Difference between revisions

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{{Adams
#REDIRECT [[NOC-AE-16003369, Applicability of Application Supplement 1 Correspondence to Supplement 2 to STP Risk-Informed GSI-191 Licensing Application]]
| number = ML16176A148
| issue date = 06/09/2016
| title = Project Units 1 and 2 - Applicability of Application Supplement 1 Correspondence to Supplement 2 to STP Risk-Informed GSI-191 Licensing Application
| author name = Connolly J
| author affiliation = South Texas Project Nuclear Operating Co
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000498, 05000499
| license number =
| contact person =
| case reference number = GSI-191, NOC-AE-16003369, TAC MF2400, TAC MF2401
| document type = Letter
| page count = 51
| project = TAC:MF2400, TAC:MF2401
| stage = Supplement
}}
 
=Text=
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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 June 9, 2016 NOC-AE-16003369 10 CFR 50.12 10 CFR 50.90 Applicability of Application Supplement 1 Correspondence to Supplement 2 to STP Risk-Informed GSl-191 Licensing Application  
<TAC NOs MF2400 and MF2401)
 
==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 Informed Approach to Resolving Generic Safety Issue (GSl)-191
," November 13, 2013, NOC-AE-13003043, ML 13323A183
: 2. Letter, G. T. Powell, STPNOC, to NRC Document Control Desk, "Supplement 2 to STP Pilot Submittal and Requests for Exemptions and License Amendment for a Informed Approach to Address Generic Safety Issue (GSl)-191 and Respond to Generic Letter (GL) 2004-02," August 20, 2015, NOC-AE-15003241, ML 15246A12ff
: 3. Letter, G. T. Powell, STPNOC, to NRC Document Control Desk, "Response to Request for Additional Information re Use of RELAP5 for Analyses for Risk-Informed GSl-191 Licensing Application," January 9, 2014, NOC-AE-13003057, ML 14029A533 (Response to ML 14009A307) . 4. Letter, G. T. Powell, STPNOC, to NRC Document Control Desk, "First Set of Responses to April 14, 2014, Requests for Additional Information Regarding STP Risk-Informed GSl-191 Licensing Application-Revised," May 22, 2014, NOC-AE-14003103, ML 14149A434 (Response to ML 14087 A075) 5. Letter, G. T. Powell, STPNOC, to NRC Document Control Desk, "Second Set of Responses to April 14, 2014, Requests for Additional Information Regarding STP Informed GSl-191 Licensing Application," June 25, 2014, NOC-AE-14003101, ML 14178A481 (Response to ML 14087A075)
: 6. Letter, G. T. Powell, STPNOC, to NRC Document Control Desk, "Third Set of Responses to April 14, 2014, Requests for Additional Information Regarding STP Risk-Informed GSl-191 Licensing Application," July 15, 2014, NOC-AE-14003105, ML 14202A045 (Respol'lse to ML 14087 A075) 7. Letter, G. T. Powell, STPNOC, to NRC Document Control Desk, "Description of Revised Risk-Informed Methodology and Responses to Round 2 Requests for Additional Information Regarding STP Risk-Informed GSl-191 Licensing Application," March 25, 2015, NOC-AE-15003220, ML 15091A440 (Response to ML 14357A171)
Reference 2 revised the methodologies used and described in Reference
: 1. References 3 -7 responded to NRC RAls on Reference 1 and portions of those responses are no longer relevant to the STPNOC application as described in Reference
: 2. The attachments identify the information that is no longer relevant and the basis for the determination.
;too r ;Jilt. STl34306886 NOC-AE-16003369 Page 2 of 3 STPNOC's process for evaluating the applicability of the RAls focused primarily on whether the response to the RAI was relevant to the revised methodology; i.e., whether a reviewer could cite it in a safety evaluation.
If the RAI for a "not applicable" response appeared still be relevant to the revised methodology and there is a docketed submittal describing how the revised methodology applies, STPNOC called the response "not applicable" and identified that reference.
However, STPNOC did not revise responses .for apparently relevant questions if the response was "not applicable" and there is no docketed reference.
A determination that a response is "not applicable" does not mean that the response is not correct. It only means that it does not apply for the current methodology.
STPNOC also reviewed Supplement 1 to the risk-informed GSl-191 application (Ref. 1) for applicability.
The results of the review are tabulated at relatively high level for each enclosure to Ref. 1. There are no commitments in this submittal.
If there are any questions, please contact Mr. Wayne Harrison at 361-972-877
: 4. I declare under penalty of perjury that the foregoing is true and correct. Executed on: Cf', :Joi{/ (} , awh Attachments:
: 1. Applicability of Supplement 1 James Connolly Site Vice President
: 2. Applicability of RAI Responses regarding Supplement 1
* 3. Definitions and Acronyms cc: (paper copy) Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 Lisa M. Regner Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (08H04) 11555 Rockville Pike Rockville, MD 20852 NRC Resident Inspector U. S. Nuclear Regulatory Commission P. 0. Box 289, Mail Code: MN116 Wadsworth, 77 483 (electronic copy) NOC-AE-16003369 Page 3 of 3 Morgan. Lewis & Bockius LLP Steven P. Frantz, Esquire U. S. Nuclear Regulatory Commission Lisa M. Regner NRG South Texas LP Chris O'Hara Jim van Suskil Skip Zahn CPS Energy Kevin Pollo Cris Eugster L. D. Blaylock Crain Caton & James. P.C. Peter Nemeth City of Austin Elaina Ball John Wester Texas Dept of State Health Services Helen Watkins Robert Free Attachment 1 Applicability of Supplement 1 NOC-AE-16003369 Attachment 1
NOC-AE-16003369 Attachment 1 Page 1 of 3 The table below addresses the applicability of Supplement 1 to STPNOC's Risk-Informed GSl-191 pilot licensing application (Reference 1 in the cover letter). The methodology change described in Supplement 2 (Reference 2 in the cover letter) revises the method of risk quantification from a detailed analysis in which conditional failure probabilities were calculated using correlations and applied in the STP PRA, to a simplified approach with a deterministic element based on plant specific testing and a risk-informed element for conditions not bounded by the testing. As a result of the methodology change, the risk quantifications in Supplement 1 are superseded by those in presented in Supplement
: 2. Methods using correlations and associated RAls no longer apply. STPNOC has also revised aspects of the requests for exemption such that the descriptions in Supplement 2 and later correspondence are the appropriate references.
' Enclosure Title Applicability Basis 1 STP Piloted Risk-Not applicable Enclosure is based on detailed analysis approach Informed Approach to which has been superseded by the Rovero method GSl-191 described in Supplement
: 2. 2-1 Request for Exemption Not applicable Exemption has been revised to be from from 1 OCFR50 .46( a)( 1) 1 OCFR50.46(b)(5) 2-2 Request for Exemption Not applicable The specific applicability and scope of the exemptions from GOC 35 have changed due to the Rovero methodology.
The 2-3 Request for Exemption Not applicable burden impact described in Supplement 1 is still from GOC 38 accurate, and is presented with less detail in 2-4 Request for Exemption Not applicable Supplement
: 2. from GOC 41 3 License Amendment Not applicable.
Superseded by LAR in Supplement
: 2. Methodology Request for STP change substantially changes the licensing basis and Piloted Risk-Informed its description in the UFSAR. Addition of change to Approach to GSl-191 the TS also supersedes the TS Bases changes in Supplement
: 1. 4-1 Volume 1 : Project Not applicable The Rovero description in the August 20, 2015 Summary supplement as updated by subsequent RAI responses provides the necessary elements of the oroiect description.
Enclosure Title Applicability 4-2 Volume 2: Probabilistic Information regarding the history Risk Analysis and configuration control of the STP PRA is applicable.
Information regarding the basis for the current STP PRA model of record is applicable.
Information regarding incorporation of conditional failure probabilities for the risk-informed GSl-191 application is Not Applicable.
4-3 Volume 3: Engineering Not applicable (CASA Grande) Information regarding the following Analysis aspects is no longer applicable:
* Time dependence of debris generation and transport
* Use of correlations for NPSH
* Use of correlations for chemical effects
* Calculation of conditional failure probabilities, including distributions Although information regarding other applications of CASA Grande may still apply, the relevant parts have been incorporated in the current Rovero methodology.
Basis NOC-AE-16003369 Attachment 1 Page 2 of 3 The Rovero approach described in the August 20, 2015 supplement does not incorporate debris-related conditional failure probabilities or revise the STP base model PRA. The Rovero approach described in the August 20, 2015 supplement does not use any of these aspects of the detailed analysis described in the November 13, 2013 supplement.
The relevant descriptions from this volume have been incorporated as needed into the current application.
Enclosure Title Applicability 5 Response to NRC Information regarding the following Supplemental aspects is no longer applicable:
Information Items:
* Time dependence of debris generation and transport
* Use of correlations for NPSH
* Use of correlations for chemical effects
* Calculation of conditional failure probabilities, including distributions
* Regulatory descriptions regarding exemptions, UFSAR changes and TS changes. 6 Changes to June 19, Not applicable 2013 Submittal Basis NOC-AE-16003369 Attachment 1 Page 3 of 3 The Rovero approach described in the August 20, 2015 supplement does not use any of these aspects of the detailed analysis described in the November 13, 2013 supplement.
The regulatory basis for the exemptions has been revised. The UFSAR changes are superseded by the current descriptions that reflect the Rovero methodology.
The current application includes a change to the ECCS and CSS Technical Specifications.
Per STPNOC letter dated 11/21/2013 (ML 13338A 165), Supplement 1 superseded the June 19, 2013 letter, so the June 19 letter is not relevant for the submittal.
Attachment 2 Applicability of RAI Responses Regarding Supplement 1 NOC-AE-16003369 Attachment 2
NOC-AE-16003369 Attachment 2 Page 1 of 40 Table 1 describes the applicability of the responses to Round 1 RAls. Table 2 describes applicability of the responses to Round 2 RAls. Most of the Table 2 responses are applicable because they were submitted at the time of the change to the Rovero methodology.
Applicability and Letter Reference for Response Not applicable ML 14202A045 (Cover Letter Ref.6) Table 1 Applicability of Responses to Round 1 RAls (ML 14087 A075) RAI APLAB, CASA Grande -General: Question 1 a, 1 b, 1c Applicability Basis The uncertainty quantification process requires characterization of parameter distributions used in sampling strategies for estimating and propagating physical model responses.
Rovero instead uses a test designed to bound the uncertainty associated with Emergency Core Cooling System (ECCS) strainer head losses. Comments Not applicable APLAB, CASA Grande -Plant Configuration:
ML 14202A045 Questions 1 a, 1 b, 2a, 2b (Cover Letter Ref.6) In order to comprehensively estimate the Reactor Containment Building (RCB) and Reactor Coolant System (RCS) responses to different break scenarios and plant states (pumping combinations), several thermal-hydraulic simulations are required to estimate the temperature and pressure histories in the RCB and RCS using coupled models of the RCB and RCS. The current Rovero methodology relies on the existing The STP Nuclear Operating Company (STPNOC) license-basis RCB analysis for strainer performance parameters; bounding test data and bounding thermal-hydraulic analysis to ensure adequate core cooling. The pump states are bounded for fiber penetration and collection (single train and two or more trains considered).
NOC-AE-16003369 Attachment 2 Page 2 of 40 Applicability and Letter RAI Reference for Response Not applicable APLAB, CASA Grande -Plant Configuration:
ML 14202A045 Question 3a, b, c (Cover Letter Ref.6) Not applicable APLAB, CASA Grande, LOCA Frequencies:
ML 14149A434 Question 1 a, 1 b (Cover Letter Ref.4) Applicability Basis In order to support the many possible ECCS and Containment Spray System (CSS) configurations, the PRA needed to have several top events added. The necessary fidelity and concomitant model support detail needed to accurately represent all possible configurations is relatively complex. The current application applies the Rovero methodology, which avoids extensive reliance on the PRA and uses what could effectively be thought of as a "LOCA Debris" initiating event frequency as a bounding CDF rather than detailed modeling in the PRA. Similarly, the PRA model of record is used to evaluate the LERF using the ratio of LERF conditional on ECCS sump screen failure for Large Break Loss of Coolant Accident (LLOCA) and CDF conditional on sump screen failure in LLOCA. The most accurate modeling of failure likelihood (Loss of Coolant Accident (LOCA)) at any given location in the RCS pressure boundary would take into consideration failure mechanisms based on causal modeling of the underlying phenomena thereby producing probabilities for each location.
Theoretically, such values could be used in sums to estimate the (preferentially) frequency (or likelihood) of a LOCA of any particular size in a plant. The STP 2013 LAR used a weighting scheme that attempted to preserve the NUREG 1829 frequencies but additionally takinQ into account in-service data .. NOC-AE-16003369 Attachment 2 Page 3 of 40 Comments Applicability and Letter RAI Reference for Response ,-Applicable APLAB, CASA Grande -LOCA Frequencies:
ML 14178A481 Question 2 Cover Letter Ref. 5 Applicability Basis where cracks were observed and some consideration of the type of service. In Rovero, a bounding method, called top-down, was adopted that avoids the need to account for weighting by relying on the fact that locations where debris amounts exceed tested levels have been mitigated.
That is, the problematic or "risk" locations have been mitigated and only the non "risk" locations have not been. The Rovero methodology ignores the mitigation improvements and equally weights the NUREG 1829 exceedance frequencies for all locations thereby bounding local effects. The STP 2013 LAR estimated breaks of any size that could be supported by a given pipe diameter.
This requires assuming a continuum of break sizes up to the pipe diameter and gives the most complete picture of possible breaks that could be used in a risk-based application.
The NUREG 1829 elicitation report can be interpreted to indicate only Double Ended Guillotine Breaks (DEGBs) can occur. Both attribution and frequency must be considered in any interpretation.
In the Rovero methodology, the continuum break model is compared to the DEGB-only model of interpretation and it automatically includes a (conservative) interpretation of attribution (spherical Zone Of Influence (ZOI) for all locations).
NOC-AE-16003369 Attachment 2 Page 4 of 40 Comments d" 
\.. Applicability and Letter RAI Reference for Response Not applicable APLAB, CASA Grande, LOCA Frequencies:
ML 14149A434 Questions
*3 & 4 (Cover Letter Ref.4) , Not applicable APLAB, CASA Grande, to PRA Interface
-General: ML 14149A434 Questions 1 a & 1 b (Cover Letter Ref.4) Applicability Basis All the elicited exceedance frequency quantiles and means aggregated in NUREG 1829 decrease rapidly with size of break. As a consequence, sampling must be done very carefully to ensure the "long tails" of the distributions are captured.
This was done in CASA Grande as described in the STP 2013 LAR using stratified sampling techniques and ensuring that the OEGB break size was sampled in each quantification.
The Rovero methodology avoids the need to perform sampling, in the way required for Monte Carlo quantification, by assuming all break sizes larger than the smallest break size producing more debris than was tested at the location are assumed to be failure. This is a conservative estimate that also avoids the possibility of inadequate sampling of long tails. The STP 2013 LAR estimates fiber mass distribution in the RCB pool, the reactor core, and the ECCS strainers.
The method used in the STP 2013 LAR performs estimates for the pump configurations assumed and calculates head loss based on collection of particulates (fiber, paint, chemical precipitates).
The Rovero methodology performs a similar calculation however, instead of looking at all possible pumping configurations, Rovero looks at 'expected' and 'extreme' cases to ensure the in-vessel effects are not limiting.
Head loss computation is not done in Rovero. Instead, re-NOC-AE-16003369 Attachment 2 Page 5 of 40 Comments Also, the current STPNOC application does not use Ref. 7 (KNF) '
Applicability and Letter RAI Reference for Response Not applicable APLAB, CASA Grande to PRA Interface-General:
ML 14202A045 Question 2a (Cover Letter Ref.4) Not applicable APLAB, CASA Grande to PRA Interface-General:
ML 14202A045 Question 2b (Cover Letter Applicability Basis suits of testing on an STP ECCS strainer module are used. Any fine fiber loading that exceeds the tested amount is assumed to lead to core damage. All the elicited exceedance frequency quantiles and means aggregated in NUREG 1829 decrease rapidly with size of break. As a consequence, sampling must be done very carefully to ensure the "long tails" of the distributions are captured.
This was done in CASA Grande as described in the STP 2013 LAR using stratified sampling techniques and ensuring that the DEGB break size was sampled in each quantification.
The Rovero methodology avoids the need to perform sampling, in the way required for Monte Carlo quantification, by assuming all break sizes larger than the smallest break size producing more debris than was tested at the location are assumed to be failure. This is a conservative estimate that also avoids the possibility of inadequate sampling of long tails. The STP 2013 LAR included timing considerations and many different break sizes and orientations.
Rovero only requires that the amounts of failed coatings assumed in the test are appropriately conservative (accepted to exceed amounts expected) or are otherwise bounded. As a consequence, no modelinQ of NOC-AE-16003369 Attachment 2 Page 6 of 40 Comments ,_ 
\ / Applicability and Letter Reference for Response Not applicable ML 14149A434 (Cover Letter Ref.4) Not applicable ML 14149A434 (Cover Letter Ref.4) Not applicable ML 14149A434 RAI APLAB, CASA Grande, to PRA Interface
-General: Question 3 APLAB, CASA Grande, to PRA Interface
-General: Questions 4a, 4b, 4c APLAB, CASA Grande, to PRA Interface
-General: Question 5 Applicability Basis failure size or timing is required in the Rovero methodology.
RAI pertains to how pump states relate to conditional failure probability which is not a feature of Rovero. Rovero discussion of ECCS single-train adequately addresses bounding pump state. In order to support the many possible ECCS and Containment Spray System (CSS) configurations, the PRA needed to have several top events added. The necessary fidelity and concomitant model support detail needed to accurately represent all possible configurations is relatively complex. The Rovero methodology avoids extensive reliance on the PRA and uses what could effectively be thought of as a "LOCA Debris" initiating event frequency as a bounding CDF rather than detailed modeling in the PRA. Similarly, the PRA model of record is used to evaluate the LERF using the ratio of LERF conditional on ECCS sump screen failure for Large Break Loss of Coolant Accident (LLOCA) and CDF conditional on sump screen failure in LLOCA. Rovero evaluation has shown that all relevant breaks are LLOCA NOC-AE-16003369 Attachment 2 Page 7 of 40 Comments Applicability and Letter RAI Reference for Response (Cover Letter Ref.4) Not applicable APLAB, CASA Grande, to PRA Interface
-General: ML 14149A434 Question 6a, 6b, 6c (Cover Letter Ref.4) Applicable APLAB, STP PRA Model-General: Questions 1, 2, Response 1, 3: 3 ML 14202A045 (Cover Letter Ref. 6) Response 2: ML 14178A481 (Cover Letter Ref. 5) Applicability Basis All the elicited exceedance frequency quantiles and means aggregated in NUREG 1829 decrease rapidly with size of break. As a consequence, sampling must be done very carefully to ensure the "long tails" of the distributions are captured.
This was done in CASA Grande as described in the STP 2013 LAR using stratified sampling techniques and ensuring that the OEGB break size was sampled in each quantification.
The Rovero methodology avoids the need to perform sampling, in the way required for Monte Carlo quantification, by assuming all break sizes larger than the smallest break size producing more debris than was tested at the location are assumed to be failure. This is a conservative estimate that also avoids the possibility of inadequate sampling of long tails. These RAls and their responses generally address the adequacy of the peer review performed for the STP PRA and the conclusions made from those reviews. Although the PRA plays a less complex part in the Rovero methodology, the assessment of its capability is still relevant.
NOC-AE-16003369 Attachment 2 Page 8 of 40 Comments Although the STP at-power PRA is suitable for the Rovero application as stated in ML 14202A045, Attachment 1, Page 4 7 of 67 does not apply as the PRA used in Rovero is not modified as described.
Rovero simply relies on reports from the at-power PRA to obtain: the Applicability and Letter RAI Reference for Response Not applicable APLAB, STP PRA Model-Success Criteria:
ML 14202A045 Question 1 (Cover Letter Ref. 6) Not applicable APLAB, STP PRA Model-Success Criteria:
ML 14202A045 Question 2a (Cover Letter Ref. 6) Not applicable APLAB, STP PRA Model-Success Criteria:
ML 14202A045 Question 2b (Cover Letter Ref. 6) Applicable APLAB, STP PRA Model-Success Criteria:
ML 14202A045 Question 2c (Cover Letter Ref. 6) Applicability Basis The 2013 LAR showed no in-core blockage that resulted in loss adequate core cooling.-While these conclusions have not changed, the STPNOC T-H analyses have been simplified in the Rovero approach.
The changes are described in the responses to the SNPB Round 3 RAls. Rovero incorporates a bounding T-H analysis Rovero incorporates a bounding T-H analysis The response provides information relevant to the application of LOCAOM to STP. However, Rovero relies on the existing The STPNOC license-basis RCB analysis for strainer performance parameters; bounding test data and bounding thermal-hydraulic analysis to ensure adequate core cooling. The pump states are bounded for fiber penetration and collection NOC-AE-16003369 Attachment 2 Page 9 of 40 Comments LERF and OeltaLERF results; and the single train frequencies.
Applicability and Letter RAI Reference for Response Not applicable APLAB, STP PRA Model-Success Criteria:
ML 14202A045 Questions 3a, 3b (Cover Letter Ref. 6) Applicable APLAB, STP PRA Model-Success Criteria:
ML 14202A045 Question 3c (Cover Letter Ref. 6) Not applicable APLAB, STP PRA Model-Success Criteria:
ML 14202A045 Question 3d (Cover Letter Ref. 6) Not applicable APLAB, STP PRA Model -Human Reliability Response to RAI Analysis:
Question 1 1, 2, 4a, 4b, 6: Applicability Basis (single train and two or more trains considered)
Rovero does not apply time dependence.
The Rovero methodology avoids extensive reliance on the PRA and uses what could effectively be thought of as a "LOCA Debris" initiating event frequency as a bounding CDF rather than detailed modeling in the PRA. Similarly, the PRA model of record is used to evaluate the LERF using the ratio of LERF conditional on ECCS sump screen failure for Large Break Loss of Coolant Accident (LLOCA) and CDF conditional on sump screen failure in LLOCA. PRA safe, stable state does not change with application of Rovero methodology.
-Question refers to the CASA-PRA interface.
The Rovero methodology does not rely on mission times for the calculation of Delta CDF, CDF or Delta LERF, LERF.
Also, Rovero methodology does not calculate conditional failure probabilities.
Human reliability analysis is required for the various actions assumed in the detailed plant model (pump operation, for example).
The human reliability analysis included in the PRA NOC-AE-16003369 Attachment 2 Page 10 of 40 Comments This basis applies to all the HRA RAls.
Applicability and Letter RAI Reference for Response ML 14149A434 (Cover Letter Ref.4) Response to RAI 3a, 3b, 3c: ML 14202A045 (Cover Letter Ref. 6) Response to RAI 5: ML 14178A481 (Cover Letter Ref. 5) Applicable APLAB, STP PRA Model -PRA Scope: Question 1 ML 14149A434 (Cover Letter Ref.4) Applicable APLAB, STP PRA Model-PRA Scope: Question 2 ML 14202A045 (Cover Letter Ref. 6 Not applicable APLAB, Results Interpretation
-ML 14149A434 Quantification:
Questions (Cover Letter 1a & 1b, 2 Ref.4) Applicability Basis model of record already includes human reliability analysis required for initiating events other than the debris event (which, when strainer success criteria are exceeded assumes core damage). In the STP 2013 LAR, the PRA required some modifications to accommodate the several new ECCS strainer and in-vessel failure modes. Rovero creates, in effect, a new initiating event for debris failure and the initiating event frequency is directly used as the in-crease in GDF (the GDF). In this way, the STP PRA does not require modification since any information needed can be obtained directly from the STP PRA. Seismic LOCA frequencies still need to be incorporated, if necessary.
The response to this RAI is still applicable.
Seismic LOCA frequencies still need to be incorporated, if necessary.
The response to this RAI is still applicable.
The Rovero methodology avoids extensive reliance on the PRA and uses what could effectively be thought of as a "LOCA Debris" initiating event frequency as a bounding GDF rather than detailed modelinq in the PRA. NOC-AE-16003369 Attachment 2 Page 11 of 40 Comments Applicability and Letter RAI Reference for Response Not applicable APLAB, Results I nterpretation-U ncertai nty ML 14202A045 Analysis:
Question 1 a (Cover Letter Ref. 6) Not applicable APLAB, Results Interpretation-Uncertainty ML 14202A045 Analysis:
Question 1 b (Cover Letter Ref. 6) Not applicable APLAB, Results Interpretation-Uncertainty ML 14202A045 Analysis:
Question 1 c (Cover Letter Ref. 6) Applicability Basis Similarly, the PRA model of record is used to evaluate the LERF using the ratio of LERF conditional on ECCS sump screen failure for Large Break Loss of Coolant Accident (LLOCA) and CDF conditional on sump screen failure in LLOCA. The STP 2013 LAR included timing considerations and many different break sizes and orientations.
Rovero only requires that the amounts of failed coatings assumed in the test are appropriately conservative (accepted to exceed amounts expected) or are otherwise bounded. No modeling of failure size or timing is required in the Rovero methodology.
Consequently, key sources of uncertainty, particularly for correlations, identified in this response do not apply for Rovero. The list of assumptions applies to the CASA Grande analysis.
The Rovero methodology has different assumptions due to the deterministic element. The Rovero methodology avoids extensive reliance on the PRA and uses what could effectively be thought of as a "LOCA Debris" initiating event frequency as a bounding CDF rather than detailed modeling in the PRA. Similarly, the PRA model of record is used to evaluate the LERF using the ratio of LERF conditional on ECCS sump screen failure for NOC-AE-16003369 Attachment 2 Page 12 of 40 Comments Uncertainties are addressed in the relevant sections of Ref. 2 to the cover letter.
Applicability and Letter RAI Reference for Response Applicable APLAB, Results Interpretation
-ML 14149A434 Uncertainty Analysis: (Cover Letter Question 2 Ref.4) Applicable APLAB, Results Interpretation-Uncertainty ML 14202A045 Analysis:
Question 3 (Cover Letter Ref. 6) Not applicable APLAB, Results Interpretation-Uncertainty ML 14202A045 Analysis:
Questions 4a, (Cover Letter 4b, 4c, 4d Ref. 6) Applicability Basis Large Break Loss of Coolant Accident (LLOCA) and COF conditional on sump screen failure in LLOCA. STPNOC's evaluation regarding applicability of the geometric mean still represents the STPNOC position that it is the appropriate metric. STPNOC's evaluation of the effect of operating life on the risk evaluation still represents the current STPNOC position regarding the use of NUREG 1829 25 service year values. However, the table of COF and LERF is not applicable because it was based on CASA Grande frequencies.
The LOCA frequency distributions described in the 2013 LAR and associated RAls are not used in the Rovero methodology.
In Rovero, a bounding method, called top-down, was adopted that avoids the need to account for weighting by relying on the fact that locations where debris amounts exceed tested levels have been mitigated.
That is, the problematic or "risk" locations have been mitigated and only the non "risk" locations have not been. The Rovero methodology ignores the NOC-AE-16003369 Attachment 2 Page 13 of 40 Comments Because the PRA community most generally adopts the geometric mean aggregation and it represents a more realistic estimate, the STPNOC adopted the geometric mean aggregation.
The Rovero methodology provides estimates of both aggregations.
Applicability and Letter Reference for Response Not applicable ML 14202A045 (Cover Letter Ref. 6 Not applicable ML 14202A045 (Cover Letter Ref. 6) ARCBRAls**
RAI Applicability Basis mitigation improvements and equally weights the NUREG 1829 exceedance frequencies for all locations thereby bounding local effects. In the Rovero methodology, the continuum break model is compared to the OEGB-only model of interpretation and it automatically includes a (conservative) interpretation of attribution (spherical ZOI for all locations).
The Rovero methodology avoids the need to perform sampling, in the way required for Monte Carlo quantification, by assuming all break sizes larger than the smallest break size producing more debris than was tested at the location are assumed to be failure. This is a conservative estimate that also avoids the possibility of inadequate sampling of long tails. APLAB, Results Section 1.2, Item 4 Interpretation-Uncertainty Analysis:
Question 5 APLAB, Results Section 1.2, Item 4 Interpretation-Uncertainty Analysis:
Question 6 NOC-AE-16003369 Attachment 2 Page 14 of 40 Comments Applicability and Letter Reference for Response Not applicable ML 14086A385 ML 14086A386 Applicable ML 14086A385 . . E.MCB R;A.ls Applicable ML 14015A311 ML 14202A045 (Cover Letter Ref. 6) ..* :'.EPNB HAis: Not applicable ML 14202A045 (Cover Letter Ref. 6) Not applicable ML 14202A045 (Cover Letter Ref. 6 RAI ARCB: Questions 1, 3 14015A045)
ARCB: Question 2 (ML 14015A045)
EMCB, Questions 1, 2 EPNB, Questions 1, 2, 3, 4,5 EPNB, Question 6a Applicability Basis The response that STPNOC made no changes to the UFSAR design basis is correct. However, the study calculation referenced for this RAI and RAI 3 (ML 14086A386) is not applicable to the Rovero methodology.
Per the draft 1 OCFR50.46c rule change, dose need not consider debris effects if risk evaluation is acce tabl small. RAI addresses resolution completion status of a design issue. Response described the resolution and is still a licable. Strainer mechanical unchanged by Rovero methodology.
See basis for APLAB, Results Uncertainty Analysis:
Questions 4a, 4b, 4c, 4d above. Break distribution and aggregation methods in the previous LAR application are not used in the Rovero methodology.
Although Rovero maintains the NUREG 1829 LOCA frequencies, the distribution methodology is different from that described in in the RAI response.
The conclusion of the NOC-AE-16003369 Attachment 2 Page 15 of 40 Comments See comments on SCVB RAls. Study calculation provides support for depth/safety margin.
Applicability and Letter Reference for Response Not applicable ML 14202A045 (Cover Letter Ref. 6) E=sGs RA1s" . . *. ':' ' Not applicable Responses to RAls 1, 2, 4, 5, 6, 8, 9, 10: ML 14202A045 (Cover Letter Ref. 6) Responses to RAIS 3, 7, 11: ML 14178A481 (Cover Letter Ref. 5) RAI EPNB, Question 6b ESGB, Chemical Effects: Question 1a, 1b, 1c, 1d, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11a Applicability Basis response still applies, but the premise has chan ed. The statement regarding the basis statistical difference is correct for Rovero; however, the references in the RAI response are not consistent with Rovero. The conclusion of the response still applies, but the premise has chan ed. The STP 2013 LAR estimates fiber mass distribution in the RCB pool, the reactor core, and the ECCS strainers.
The method used in the STP 2013 LAR performs estimates for the pump configurations assumed and calculates head loss based on collection of particulates (fiber, paint, chemical precipitates).
The Rovero methodology performs a similar calculation however, instead of looking at all possible pumping and debris configurations, Rovero looks at 'expected' and 'extreme' cases to ensure the in-vessel effects are not limiting.
Head loss computation is not done in Rovero. Instead, results of testing on an STP ECCS strainer module are used. Any fine fiber loading that exceeds the tested amount is assumed to lead to core damage. NOC-AE-16003369 Attachment 2 Page 16 of 40 Comments Applicability and Letter RAI Reference for Response Not applicable ESGB, Chemical Effects: Question 11 b ML 14178A481 (Cover Letter Ref. 5) Not applicable ESGB, Chemical Effects: Question 12, 13a, 13b, ML 14149A434 13c (Cover Letter Ref.4) Not applicable ESGB, Chemical Effects: Question 14a, 14b, 14c ML 14202A045 (Cover Letter . Ref. 6) Not applicable ESGB, Chemical Effects: Question 15 ML 14202A045 (Cover Letter Ref. 6) Not applicable ESGB, Chemical Effects: Question 16 ML t 4202A045 Applicability Basis The RAI pertains to bump-up factors, which are not applicable to the Rovero methodology.
Tin powder was used as a surrogate for zinc in plant-specific testing. These RAI and responses are applied in the context of supporting chemical effects on head loss. The 2013 LAR process requires characterization of parameter distributions used in sampling strategies for estimating and propagating physical model responses and for development of correlations.
Rovero instead uses a test designed to bound the uncertainty associated with Emergency Core Cooling System (ECCS) strainer head losses. RAI was directed toward chemical effects testing associated with CASA Grande correlations.
The Rovero methodology is based on accepted deterministic testing . See response above for ESGB Chemical Effects RAI 12, 13a, 13b, 13c See response above for ESGB Chemical Effects RAI 12, 13a, 13b, 13c. NOC-AE-16003369 Attachment 2 Page 17 of 40 Comments Although the STP deterministic testing that supports Rovero was not addressed in the responses, The test results show nothing that affects the conclusions of the Rovero deterministic testing.
Applicability and Letter RAI Reference for Response (Cover Letter Ref. 6) Not applicable ESGB, Chemical Effects: Question 17 ML 14178A481 (Cover Letter Ref. 5) Not applicable ESGB, Chemical Effects: Question 18a ML 14202A045 (Cover Letter Ref. 6) Not applicable ESGB, Chemical Effects: Question 18b ML 14202A045 (Cover Letter Ref. 6) Not applicable ESGB, Chemical Effects: Question 18c ML 14202A045 (Cover Letter Ref. 6) Applicability Basis Response to RAI addresses variations in pH and amounts of LOFG from different break sizes. Those variations are not required for the Rovero deterministic testinQ. The RAI and response relate to correlations and chemical effects "bump up" factors which are not used in the Rovero methodology.
Testing credited in Rovero methodology used WCAP-16530 process. The RAI and response supports evaluation of the CASA Grande modeling and and correlations which are not used in the Rovero methodology.
Rovero looks at 'expected' and 'extreme' cases to ensure the in-vessel effects are not limiting.
Head loss computation is not done in Rovero. Instead, results of testing on an STP ECCS strainer module are used. Any fine fiber loading that exceeds the tested amount is assumed to lead to core damage. Although the response clarifies a typographical error, the information in the affected graphics related to the CASA Grande analyses that are not used in the Rovero methodology.
See response to 18b above. NOC-AE-16003369 Attachment 2 Page 18 of 40 Comments Response also indicates that the information cited in the RAI was not used in the 2013 LAR analyses.
Applicability and Letter RAI Reference for Response Not applicable ESGB, Chemical Effects: Question 19 ML 14149A434 (Cover Letter Ref.4) Not applicable ESGB, Chemical Effects: Question 20 ML 14178A481 (Cover Letter Ref. 5) Applicable ESGB, Chemical Effects: Question 21 ML 14202A045 (Cover Letter Ref. 6) Not applicable ESGB, Chemical Effects: Question 22a, 22b ML 14178A481 (Cover Letter Ref. 5) Applicability Basis See response to ESGB RAI 18b above. The RAI and response relate to correlations and chemical effects "bump up" factors which are not used in the Rovero methodology.
See ESGB RAl-33 in Round 2 (Table 2 below) The CHLE test program is not applicable to the Rovero methodology or associated plant-specific test. NOC-AE-16003369 Attachment 2 Page 19 of 40 Comments This basis is generally applicable to RAls and responses regarding the CHLE testing. As stated in the response to ESGB Chemical Effects RAI 22b, "The objective of the CHLE testing program was to generate experimental data to support an overall risk-informed approach to the resolution of GSl-191, while also conducting a manageable number of tests." Although the CHLE tests and results can provide insight with respect to margin in the deterministic testinq that supports Applicability and Letter RAI Reference for Response Applicable ESGB, Coatings:
Question 1 Not applicable ESGB, Coatings:
Question 2 ML 14149A434 (Cover Letter Ref.4) Applicable ESGB, Coatings:
Question 3 ML 14149A434 (Cover Letter Ref.4) Not applicable ESGB, Coatings:
Questions 4, 5, 6a, 6b, 6c Responses to RAls 4, 5: ML 14149A434 (Cover Letter Ref.4) Response to RAI 6a, 6b, 6c: ML 14202A045 (Cover Letter Ref. 6) Applicability Basis Original response and response to RAI SSIB-3-6 in ML 16082A507 address epoxy coatings IOZ quantified differently for the Rovero evaluation Unqualified coatings are assumed to fail at 100% The STP 2013 LAR included timing considerations and many different break sizes and orientations.
Rovero only requires that the amounts of failed coatings assumed in the test are appropriately conservative (accepted to exceed amounts expected) or are otherwise bounded. As a consequence, no modeling of failure size or timing is required in the Rovero methodology.
NOC-AE-16003369 Attachment 2 Page 20 of 40 Comments Rovero, the Rovero methodology and STPNOC LAR does not rely on them.
Applicability and Letter Reference for Response Applicable ML 14149A434 (Cover Letter Ref.4 SCVBRAl's' Applicable
,,,> RAI ESGB, Coatings:
Question 7 SCVB, Question: 1 a Applicability Basis Coatings program description is still applicable for the Rovero methodology Exemption to CSS still required for Rovero NOC-AE-16003369 Attachment 2 Page 21 of 40 Comments The SCVB RAls are relevant to the STPNOC application.
The ML 14178A481 pre-Rovero responses provided (Cover Letter in ML 14178A481 (A485 rR:-:--ef_.
_5'---:":----+-:::---------+-------------------i attachment) are updated by Not applicable SCVB, Question: 1 b See comment. STPNOC changed single failure responses provided in response in ML 15246A126 ML 15091A440 dated March 25, ML 14178A481 2015 as revised in Attachment 1-(Cover Letter 6 to Supplement 2 of the Ref. 5 STPNOC submittal t--:--:--'-:-:------t--c:c-::----,---,------t---------------------J Applicable SCVB, Question:
2a Exemption to CSS still required for Rovero (ML 15246A128) to reflect the Rovero methodology changes. ML 14178A481 (Cover Letter Also, in accordance with the Ref. 5 proposed 1 OCFR50.46c rule Not applicable SCVB, Question:
2b See comment. STPNOC changed single failure change, "The NRC approval of response in ML 15246A 126 an entity's risk-informed ML 14178A481 approach allows the enity to (Cover Letter exclude the effects of debris in its Ref. 5) analysis of long-term cooling ... ".
In addition, the NRCappliedthe ML 14178A481 (Cover Letter Ref. 5 document has been revised to references same rationale to the relationship shown in comment. of 1 OCFR50.46c to other regulations; i.e., GOC 35, 38 and 41. Since STPNOC met those Applicability and Letter RAI Reference for Response Not applicable SCVB, Question:
3b ML 14178A481 (Cover Letter Ref. 5) Applicable SCVB, Question:
3c ML 14178A481 (Cover Letter Ref. 5) Applicable SCVB, Question:
4a ML 14178A481 (Cover Letter Ref. 5) Applicable SCVB, Question:
4b ML 14178A481 (Cover Letter Ref. 5) Applicable SCVB, Question:
4c ML 14178A481 (Cover Letter Ref. 5) Not applicable SCVB, Question:
5 ML 14178A481 (Cover Letter Ref. 5) Applicability Basis See comment. The description is superseded by Rovero. Generally applicable, but original reference document has been revised to references shown in comment. Generally applicable, but original reference document has been revised to references shown in comment. Rovero methodology has no impact on response.
Generally applicable, but original reference document has been revised to references shown in comment. See comment. Rovero does not use time-dependent containment analyses, and does not change the CLB containment analysis NOC-AE-16003369 Attachment 2 Page 22 of 40 Comments requirements by showing that the effects of debris are small in accordance with RG 1.17 4 (considering COF, LERF, safety margin and defense-in-depth), the CLB design basis for containment need not be revised. '
Applicability and Letter Reference for Response Applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14178A481 (Cover Letter Ref. 5 Not applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14178A481 (Cover Letter Ref. 5 Not applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14178A481 (Cover Letter Ref. 5 RAI SCVB, Question:
6 SCVB, Question:
7 SCVB, Question:
8 SCVB, Question:
9a SCVB, Question:
9b Applicability Basis See comment. Rovero does not change the containment analysis (current LB calculation is used). The response still applies with respect to how Rovero is used to assess debris effects. RELAP5 screening cases have changed and are being reviewed by SNPB. Rovero methodology still requires exemption to GOC 35. See comment. STPNOC changed single failure response in ML 15246A 126 SNPB Questions:
1 a, 1 b, Used by NRC for their thermal-hydraulic review 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j, 1k, 11, 1m, 2a, 2b, 2c, 2d,3,5 NOC-AE-16003369 Attachment 2 Page 23 of 40 Comments Applicability and Letter Reference for Response Not applicable ML 14202A045 (Cover Letter Ref. 6) Applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14202A045 (Cover Letter Ref. 6 Not applicable ML 14202A045 (Cover Letter Ref. 6 Applicable ML 14202A045 (Cover Letter Ref. 6 Applicable ML 14202A045 (Cover Letter Ref. 6 RAI SNPB, Question 4 SNPB, Question:
5 SRXB, Question 1 SRXB, Question 2 SRXB, Question 3 SRXB, Question 4 Applicability Basis STP BAP LB calculation has been revised since this STPNOC responded to this RAI and was the subject of an NRC audit. STP BA concentration is not calculated in the Rovero methodology NRC review of RELAP5 documentation Not using 30 capability of RELAP5 30 NRG review of RELAP5 documentation NRC review of RELAP5 documentation NOC-AE-16003369 Attachment 2 Page 24 of 40 Comments These also address the applicability of Reference 3 of the cover letter.
Applicability and Letter RAI Reference for Response Not applicable SRXB, Question Sa ML 14149A434 (Cover Letter Ref.4) Not applicable SRXB, Question Sb ML 14149A434 (Cover Letter Ref.4) Not applicable SRXB, Question Sc ML 14149A434 (Cover Letter Ref.4) Not applicable SRXB, Question 6 Applicable SRXB, Question 7a, 7b ML 14149A434 (Cover Letter Ref.4) Not applicable SRXB, Question 8 ML 14149A434 (Cover Letter Ref.4) Applicable SRXB, Question 9 ML 14149A434 Applicability Basis Limiting values used in Rovero methodology Table not used Rovero uses different assumptions for the calculation.
Part of input for conditional failure probabilities, which are not being used in Rovero HLSO procedure is not changed for Rovero methodology Rovero applies bounding sensitivities for ECCS flow -Flow combination definitions still apply NOC-AE-16003369 Attachment 2 Page 25 of 40 Comments Not using CASA Grande to calculate these values.
Applicability and Letter Reference for Response (Cover Letter Ref.4 Applicable ML 14149A434 (Cover Letter Ref.4 Applicable ML 14149A434 (Cover Letter Ref.4 Not applicable Applicable Not applicable ML 14149A434 (Cover Letter Ref.4 Applicable ML 14202A045 (Cover Letter Ref. 6) RAI SSIB, ZOI: Question 1 SSIB, Debris Characteristics:
Question 2 SSIB, Debris Characteristics:
Question 3 SSIB, Transport:
Question 4 SSIB, Transport:
Question 5 SSIB, Transport:
Question 6a, 6b, 6c, 6d, 6e, ?a, 7b, 7c, 7d, 7e Applicability Basis Debris transport in CASA still required Debris transport in CASA still required Not using head loss correlation Debris transport in CASA still required Supplement 2 establishes transport fraction for pool fill at 5%. Debris generation and transport models are not changed. NOC-AE-16003369 Attachment 2 Page 26 of 40 Comments Applicability and Letter Reference for Response Applicable, ML 14202A045 (Cover Letter Ref. 6) Applicable ML 14202A045 (Cover Letter Ref. 6) Not applicable ML 14149A434 (Cover Letter Ref.4) Applicable ML 14202A045 (Cover Letter Ref. 6) Not applicable ML 14149A434 (Cover Letter Ref.4) Not applicable ML 14149A434 (Cover Letter Ref.4) Applicable RAI SSIB, Transport:
Question 7f SSIB, Transport:
Question 8a, Sb, Sc, Sd, Se SSIB, Transport:
Question 9 SSIB, Transport:
Question 10 SSIB, Transport:
Question 11 a SSIB, Transport:
Question 11 b SSIB, Transport:
Question 11 c Applicability Basis RAI was an editorial correction STPNOC assumes no credit for hold up of partially submerged debris on the concrete of the operating deck. The revised methodology holds up and erodes smalls instead of transporting them. Discussion of no transport after sprays are secured is still valid. Correlations are not used in Rovero Correlations are not used in Rovero Basis is not changed for Rovero NOC-AE-16003369 Attachment 2 Page 27 of 40 Comments ,
Applicability and Letter Reference for Response ML 14149A434 (Cover Letter Ref.4) Not applicable ML 14149A434 (Cover Letter Ref.4) Not applicable ML 14149A434 (Cover Letter Ref.4) Applicable Applicable ML 14149A434 (Cover Letter Ref.4) Not applicable ML 14202A045 (Cover Letter Ref. 6) Not applicable ML 14202A045 (Cover Letter Ref. 6) RAI SSIB, Transport:
Question 11 d SSIB, Transport:
Question 11 e SSIB, Transport:
Question 12 SSIB, Transport:
Question 13 SSIB, Head Loss and Chemical Effects Bump Up: Question 14 SSIB, Head Loss and Chemical Effects Bump Up: Question 15a, 15b, 15c, 15d, 16a, 16b, 16c, 16d, 17a, 17b, 17c, 17d, 17e, 17f, 18a, 18b, 18c, Applicability Basis Correlations are not used in Rovero Correlations are not used in Rovero Transport model not changed Micro-Therm still transports as fines in current methodology.
Head loss correlations are not used in Rovero Head loss correlations are not used in Rovero NOC-AE-16003369 Attachment 2 Page 28 of 40 Comments Applicability and Letter Reference for Response Not applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14202A045 (Cover Letter Ref. 6) Not applicable ML 14202A045 (Cover Letter Ref. 6) Applicable ML 14149A434 (Cover Letter Ref.4) RAI 18d, 18e, 19,20,21a, 21b,21c,21d,22,23,24 SSIB, Head Loss and Chemical Effects Bump-up: Questions 25a, 25b, 26a,26b,26d,26e,26f SSIB, Head Loss and Chemical Effects Bump-up: Question 26c SSIB, Head Loss and Chemical Effects Bump Up: Question 27 SSIB, Head Loss and Chemical Effects Bump Up: Question 28 SSIB, NPSH and Oegasification:
Question 29 Applicability Basis Head loss correlations are not used in Rovero Strainer loading related to actual performance compared to test Strainer LB NPSH Head loss correlations are not used in Rovero Strainer NPSH NOC-AE-16003369 Attachment 2 Page 29 of 40 Comments Not a CASA Grande calculation for current application; however, STP Engineering calculation includes the same considerations Applicability and Letter RAI Reference for Response Not applicable SSIB, NPSH and Degasification:
Question ML 14178A481 30 (Cover Letter Ref. 5 Applicable SSIB, NPSH and Degasification:
Question ML 14178A481 31 (Cover Letter Ref. 5 Applicable SSIB, NPSH and Degasification:
Question ML 14178A481 32 (Cover Letter Ref. 5 Not applicable SSIB, NPSH and Degasification:
Question ML 14178A481 33 (Cover Letter Ref. 5 Not applicable SSIB, NPSH and Degasification:
Question ML 14178A481 34 (Cover Letter Ref. 5 Not applicable SSIB, NPSH and Degasification:
Question ML 14178A481 35 (Cover Letter Ref. 5 Applicability Basis NPSHR is now a different calculation that credits accident pressure.
Response is superseded by response to SSIB Follow up RAls 33 and 34. Strainer LB NPSH Strainer LB NPSH Not done with CASA Grande methodology for current LAR supplement.
This was done in the deterministic calculation by Enercon. Containment Spray flows are addressed in FIDOE discussion in Attachment 1-3 to cover letter Ref.2 (ML 15246A 126 cover /127 attachment)
The CASA evaluation described in the RAI 35 response used the equivalent diameter to assign LOCA category.
Rovero does not assign LOCA categories based on equivalent diameter.
NOC-AE-16003369 Attachment 2 Page 30 of 40 Comments Portions of the response related to use of CASA Grande are not applicable STP Engineering calculation instead of CASA Grande calculation.
Applicability and Letter RAI Reference for Response Not applicable SSIB, NPSH and Degasification:
Question ML 14202A045 36 (Cover Letter Ref. 6) Not applicable SSIB, In-Vessel and Boric Acid Precipitation:
ML 14178A481 Question 37 (Cover Letter Ref. 5 Not applicable SSIB, NPSH and Degasification:
Question ML 14202A045 38 (Cover Letter Ref. 6) Applicable SSIB, Debris Bypass: Question 39a, 39b, 39c, ML 14178A481 39d, 39e, 39f (Cover Letter Ref. 5 Not applicable SSIB, Defense In Depth and Mitigative Measures:
ML 14202A045 Question 40 (Cover Letter Ref. 6) Not applicable SSIB, Defense in Depth and Mitigative Measures:
ML 14178A481 Question 41 a (Cover Letter Ref. 5 Applicability Basis Superseded by information in Att. 1-2 p.56 cover letter Ref. 2, (ML 15246A126 cover letter/ A 127 attachment)
See BAP discussion in Att. 1-3 to cover letter Ref. 2, (ML 15246A126 cover letter/A127 attachment)
See FIDOE discussion in Att. 1-3 of cover letter Ref. 2, (ML 15246A126 cover letter/A127 attachment)
Debris bypass is required for downstream analysis in Rovero. See DID and Safety Margin in Att. 1-4 to cover letter Ref. 2, (ML 15246A126 cover/A127 attachment)
Risk methodology has changed NOC-AE-16003369 Attachment 2 Page 31 of 40 Comments References to earlier CDF and LERF are not applicable, but qualitative discussion still applies. Discussion with regard to EOPs is applicable.
Description of application of risk methodology is not applicable.
Applicability and Letter Reference for Response Applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14178A481 (Cover Letter Ref. 5 Applicable ML 14202A045 (Cover Letter Ref. 6 'STSBRAls.
Not applicable ML 14149A434 (Cover Letter Ref.4 Not applicable ML 14149A434 (Cover Letter Ref.4 RAI SSIB, Defense in Depth and Mitigative Measures:
Question 41 b SSIB, Defense in Depth and Mitigative Measures:
Question 41 c SSIB, Defense in Depth and Mitigative Measures:
Question 41 d Applicability Basis DID and SM required by RG 1.174 DID and SM required by RG 1.174 DID and SM required by RG 1.17 4 SSIB, Defense In Depth DID and SM required by RG 1.174 and Mitigative Measures:
Question 42 STSB: Question 1 Although response accurately describes application of RMTS, RMTS would not be required for proposed 90-day completion time STSB: Question 2 Although response accurately describes application of RMTS, RMTS would not be required for proposed 90-day completion time NOC-AE-16003369 Attachment 2 Page 32 of 40 Comments Applicability and Letter Reference for Response Applicable ML 14149A434 (Cover Letter Ref.4) Applicability (All responses are in ML 15091A440)
Applicable Not applicable Applicable Applicable RAI Applicability Basis STSB: Question 3 Engineering change control still manages quantities of material going into RCB Table 2 Applicability of Responses to Round 2 RAls (ML 14357A171)
RAI Question 1 : Project Quality Assurance Question 2: Project Quality Assurance Question 3: Project Quality Assurance Question 4: Project Quality Assurance Applicability Basis Appropriate quality controls required for license activities CASA Grande 1.7.2 is controlled in accordance with the STPNOC SQA program Appropriate quality controls required for license activities Appropriate quality controls required for license activities NOC-AE-16003369 Attachment 2 Page 33 of 40 Comments Comments Applicability (All responses RAI are in ML 15091A440)
Applicable Question 1: Treatment of Unanalyzed Plant Conditions Applicable Question 7: Human Reliability Analysis Applicable Question 1 : Key Assumptions/Key Sources of Uncertainty Applicable Question 1 : Validity of Assumption on Pump Configurations Applicable Question 7: CASA Grande to PRA Interface Applicable Question 1: Fidelity between RELAP Simulations and CASA Grande Applicable Question 1: State-of-Knowledge Correlation Applicability Basis Appropriately refers to Rovero Appropriately refers to Rovero Appropriately refers to Rovero Appropriately refers to Rovero Appropriately refers to Rovero. The methodology now strictly looks for smallest break size below which tested fines amounts are not exceeded.
Appropriately refers to Rovero Appropriately refers to Rovero. Rovero does not calculate failure probabilities.
Instead, Rovero calculates core damage frequencies come from direct evaluation of the NU REG 1829 quantiles and means. NOC-AE-16003369 Attachment 2 Page 34 of 40 Comments Applicability (All responses RAI are in ML 15091A440)
Applicable Question 1 : Selection of Johnson Parameters Applicable Question 2 ..
.. ). .*.. :****:. <L '*!< . :' .," *,' , '; ,;_;:',' .... :** ) "":' .'.-. Applicable Question 23: Chemical Effects Applicable Question 24: Chemical Effects Applicable Question 25: Chemical Effects Applicable Question 26: Chemical Effects Applicable Question 27: Chemical Effects Applicable
[ML 15091A440]Question 28: Chemical Effects Applicable Question 29: Chemical Effects Applicable Question 30: Chemical Effects Applicable Question 31: Chemical Effects Applicable Question 32: Chemical Effects / Applicability Basis Appropriately refers to Rover 0. Rovero evaluates calculates core damage frequencies from direct evaluation of the NU REG 1829 quantiles and means. Strainer mechanical must be met for Rovero. .*: :.* . '::t. ;..:* ..... ;. **.*.* **o:-::**, !>;. : :: *... ......
...... .I* *o*:;* .. >*'.\. :. .'" Appropriately refers to Rovero Appropriately refers to Rovero Appropriately refers to Rovero Appropriately refers to Rovero Appropriately refers to Rovero Appropriately refers to Rovero. Appropriately refers to Rovero. Appropriately refers to Rovero. Appropriately refers to Rovero. Appropriately refers to Rovero. NOC-AE-16003369 Attachment 2 Page 35 of 40 Comments Also addressed in Att. 1-2 to cover letter Ref. 2, p. 81-82 (ML 15246A 126 cover letter/ A 127 attachment)
'./ .. ;: . :i'*c:: .. *: ***.: . . '. *;;::i'. .. :. ;:,: .*. ":: */* '; . ' *,:*:"" : ....
Applicability (All responses are in ML 15091A440)
Applicable Not applicable Applicable Applicable Applicable Not applicable Applicable Applicable RAI Question 33: Chemical Effects Question 34: Chemical Effects Question 8: Coatings Question 9: Coatings Question 1 O: Coatings Responses to SCVB RAls 10 -18 from NRC letter dated March 3, 2015(ML14357A171), as provided in STPNOC letter dated March 25, 2015 ML 15091A440 . Question 6 Question 7 Applicability Basis Response not affected by methodology change. Rovero does not use correlations to evaluate strainer head loss. All unqualified coatings were included in the STP 2008 strainer test used by Rovero. This is also addressed in Round 3 SSIB RAls. Response appropriately refers to Rovero Response appropriately refers to Rovero methodology.
Revised responses to each of these RAls were provided in Att. 1-6 to STPNOC's August 20, 2015, Supplement 2 to the application (ML 15246A128)
BAP must be met in Rovero BAP must be met in Rovero NOC-AE-16003369 Attachment 2 Page 36 of 40 Comments Response is applicable in that it provides the clarification re uested b the reviewer.
Topic to be further addressed in response to Round 3 RAls sent in ML 16082A507 Topic to be further addressed in response to Round 3 RAls sent in ML 16082A507 Also see evaluation of responses to initial SCVB RAls 1 -9, above BAP is also addressed in later RA ls BAP is also addressed in later RA ls Applicability (All responses RAI are in ML 15091A440)
Applicable Question 8 Applicable Question 9 Applicable Question 10 Applicable Question 43 Applicable Question 44 Not applicable Question 45 Applicable Question 46 Applicable Question 47 Applicable Question 48 Applicable Question 49 Applicability Basis BAP must be met in Rovero BAP must be met in Rovero Rovero does not rely on HLSO timing Rovero uses debris generation and transport to find critical/
non-critical weld locations Rovero uses debris generation and transport to find critical/
non-critical weld locations Fractions have changed from 11/2013 LAR Rovero uses debris generation and transport to find critical/
non-critical weld locations Rovero is appropriately referenced.
Rovero is appropriately referenced.
Rovero requires strainer performance calculation NOC-AE-16003369 Attachment 2 Page 37 of 40 Comments BAP is also addressed in later RA ls BAP is also addressed in later RA ls Note that statement that "Rovero analysis relies on current UFSAR hot leg switchover time" only means that Rovero does not do a calculation that depends on HLSO time. The Rovero analysis shows there is no effect of debris on BAP. Revised fractions are provided in response to Round 3 SSIB RAI-3.
Applicability (All responses RAI are in ML 15091A440)
Applicable Question 50 Applicable Question 51 Applicable Question 52 Not applicable Question 53 Applicable Question 54 Applicable Question 55 Applicable Question 55a Applicable Question 56 Applicable Question 57(a) Applicable Question 57(b) Applicable Question 57(c) Applicable Question 57(d) Applicability Basis Rovero is appropriately referenced in the response and does not use correlations for head loss Rovero requires strainer performance calculation and response appropriately refers to 2008 evaluations.
Rovero requires strainer performance calculation and response appropriately refers to 2008 evaluations.
Rovero does not use probability distributions for performance modeling Rovero requires strainer performance calculation Response provides clarification for implementation of backwash as defense-in-depth Rovero does not use correlations for head loss Rovero requires strainer penetration calculation Rovero requires strainer penetration calculation Rovero requires strainer penetration calculation Rovero requires strainer penetration calculation Rovero requires strainer penetration calculation NOC-AE-16003369 Attachment 2 Page 38 of 40 Comments Round 3 RAls also address flashing Applicability (All responses RAI are in ML 15091A440)
Applicable Question 57(e) Applicable Question 57(f) Not applicable Question 58 Applicable Question 59 Applicable Question 60 Applicable Question 61 Applicable Question 62 Applicable Question 63 Applicable Question 64 Applicable Question 65 Applicable Question 66 Applicability Basis Rovero requires strainer penetration calculation Rovero requires strainer penetration calculation Although there are some parallels, Rovero uses a different sampling process. Rovero requires the CAD model and CASA Grande for debris generation and transport Latent fiber and eroded fiber are required for Rovero Rovero requires the CAD model and CASA Grande for debris generation and transport Rovero does not use correlations for head loss Rovero does not use correlations for head loss Rovero does not use correlations for head loss Rovero does not use correlations for head loss Rovero addresses BAP as required by NRC guidance NOC-AE-16003369 Attachment 2 Page 39 of 40 Comments Note that statement that "Rovero analysis relies on current UFSAR hot leg switchover time" only means that Rovero does not do a calculation that depends on HLSO time. The Rovero analysis shows there is no effect of debris on BAP.
Applicability (All responses are in ML 15091A440)
Applicable RAI Question 4 Applicability Basis Application to clarify use of risk information NOC-AE-16003369 Attachment 2 Page 40 of 40 Comments August 20, 2015, Supplement 2 proposed TS changes that are consistent with the description in this RAI. Further information will be provided in response to Round 3 RAI from STSB.
Attachment 3 Definitions and Acronyms NOC-AE-16003369 Attachment 3
NOC-AE-14003101 Attachment 9 Page 1of2 Definitions and Acronyms ANS American Nuclear Society EOF Emergency Operations ARL Alden Research Laboratory Facility ASME American Society of EOP Emergency Operating Mechanical Engineers Procedure(s)
BA Boric Acid EPRI Electric Power Research BAP Boric Acid Precipitation Institute BC Branch Connection EQ Equipment Qualification BEP Best Efficiency Point ESF Engineered Safety Feature B-F Bimetallic Welds FA Fuel Assembly(s)
B-J Single Metal Welds FHB Fuel Handling Building BWR Boiling Water Reactor GDC General Design Criterion(ia)
CAD Computer Aided Design GL Generic Letter CASA Containment Accident GSI Generic Safety Issue Stochastic Analysis 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 lntergranular 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 eves . Chemical Volume Control LHS Latin Hypercube Sampling System LHSI Low Head Safety Injection OBA 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/MEAS 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 ECCS Emergency Core Cooling NIST National Institute of System Standards and Technology ECWS Essential Cooling Water NLHS Non-uniform Latin Hypercube System (also ECW) Sampling NOC-AE-14003101 Attachment 9 Page 2 of 2 Definitions and Acronyms NPSH Net Positive Suction Head, RWST Refueling Water Storage (NPSHA -available, NPSHR Tank -required)
SBLOCA Small Break Loss of Coolant NRC Nuclear Regulatory Accident Commission SC Stress Corrosion NSSS Nuclear Steam Supply SI/SIS Safety Injection, Safety System Injection System (same as OBE Operating Basis Earthquake ECCS) OD Outer Diameter SIR Safety Injection and PCI Performance Contracting, Recirculation Inc. SR Surveillance Requirement PCT Peak Clad Temperature SRM Staff Requirements PDF Probability Density Function Memorandum PRA Probabilistic Risk SSE Safe Shutdown Earthquake Assessment STP South Texas Project PWR Pressurized Water Reactor STPEGS South Texas Project Electric PW ROG Pressurized Water Reactor Generating Station Owner's Group STPNOC STP Nuclear Operating PWSCC Primary Water Stress Company Corrosion Cracking TAMU Texas A&M University QDPS Qualified Display Processing TF Thermal Fatigue System TGSCC Transgranular Stress RAI Request for Additional Corrosion Cracking Information TS Technical Specification( s) RCB Reactor Containment TSB Technical Specification Building Bases RCFC Reactor Containment Fan TSC Technical Support Center Cooler TSP Trisodium Phosphate RCS Reactor Coolant System UFSAR Updated Final Safety RG Regulatory Guide Analysis Report RHR Residual Heat Removal UNM University of New Mexico RI-ISi Risk-Informed In-Service USI Unresolved Safety Issue Inspection UT University of Texas (Austin) RMI Reflective Metal Insulation V&V Verification and Validation RMTS Risk Managed Technical VF Vibration Fatigue Specifications WCAP Westinghouse Commercial Rovero Risk over Deterministic Atomic Power Methodology ZOI Zone of Influence RVWL Reactor Vessel Water Level}}

Latest revision as of 12:29, 20 April 2019

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