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| | number = ML12159A111 | | | number = ML12159A111 |
| | issue date = 06/06/2012 | | | issue date = 06/06/2012 |
| | title = Fire Modeling Requests for Additional Information, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) (TAC No. ME7046) | | | title = Fire Modeling Requests for Additional Information, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) |
| | author name = | | | author name = |
| | author affiliation = NRC/NRR/DRA/AFPB | | | author affiliation = NRC/NRR/DRA/AFPB |
Letter Sequence RAI |
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MONTHYEARML1124200222011-08-29029 August 2011 Request for License Amendment to Adopt NFPA 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (2001 Edition) (License Amendment Request Ldcn 11-0012) Project stage: Request ULNRC-05823, Clarification of Information Contained in Request for License Amendment to Adopt NFPA 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (2001 Edition) (LDCN 11-0012)2011-11-0909 November 2011 Clarification of Information Contained in Request for License Amendment to Adopt NFPA 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (2001 Edition) (LDCN 11-0012) Project stage: Request ML1132602802011-11-22022 November 2011 Acceptance Review Email, Request for License Amendment to Adopt National Fire Protection Association (NFPA) Standard 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: Acceptance Review ML1132604512011-11-22022 November 2011 Correction Acceptance Review Email, Request for License Amendment to Adopt National Fire Protection Association (NFPA) Standard 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: Acceptance Review ML1201804512012-01-19019 January 2012 Regulatory Audit Plan for License Amendment Request to Implement NFPA 805, Risk-Informed, Performance-Based, Fire Protection Program Pursuant to 10 CFR 50.48(c) Project stage: Other ML1206004022012-02-15015 February 2012 Email, Request for Additional Information, Request to Adopt National Fire Protection Association (NFPA) Standard 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML1206004072012-02-15015 February 2012 Email, Request for Additional Information, Request to Adopt National Fire Protection Association (NFPA) Standard 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML1206001862012-03-0202 March 2012 Request for Additional Information, Amendment Request to Adopt National Fire Protection Association (NFPA) Standard 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML12108A2402012-04-17017 April 2012 Enclosure 1 to ULNRC-05851, Request for Additional Information (RAI) with Callaway Plant Response Project stage: Request ULNRC-05851, Response to Request for Additional Information Regarding Adoption of National Fire Protection Association Standard NFPA 8052012-04-17017 April 2012 Response to Request for Additional Information Regarding Adoption of National Fire Protection Association Standard NFPA 805 Project stage: Response to RAI ML12159A0942012-06-0606 June 2012 Email Request for Additional Information Round 2, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: Request ML12159A1032012-06-0606 June 2012 PRA Requests for Additional Information, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML12159A1112012-06-0606 June 2012 Fire Modeling Requests for Additional Information, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML1217104322012-06-19019 June 2012 Email, Request for Additional Information Round 3, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML1217104442012-06-19019 June 2012 Apla, Request for Additional Information Round 3, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML1217104392012-06-19019 June 2012 Afpb, Request for Additional Information Round 3, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ULNRC-05876, Response to Request for Additional Information Re Adoption of National Fire Protection Association Standard NFPA 8052012-07-12012 July 2012 Response to Request for Additional Information Re Adoption of National Fire Protection Association Standard NFPA 805 Project stage: Response to RAI ML12335A2322012-12-11011 December 2012 Request for Additional Information, Round 2, Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML13008A3542013-01-0303 January 2013 Email Request for Additional Information,License Amendment Request to Adopt NFPA 805 Project stage: RAI ML13008A3502013-01-0808 January 2013 Email, Request for Additional Information License Amendment Request to Adopt NFPA 805 Project stage: RAI ML13022A0242013-01-22022 January 2013 Email, Two Revised Requests for Additional Information from 12/11/12 Ltr, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants. Project stage: RAI ULNRC-05952, Regarding Adoption of National Fire Protection Association Standard NFPA 8052013-02-19019 February 2013 Regarding Adoption of National Fire Protection Association Standard NFPA 805 Project stage: Other ML13051A4502013-02-19019 February 2013 Enclosure 1, W/Attachments to ULNRC-05952 - Request for Additional Information (RAI) with Callaway Plant, Response Project stage: Request ML13204A2232013-07-30030 July 2013 Request for Additional Information, License Amendment Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML13260A5912013-08-16016 August 2013 Request for Additional Information Email, Nrr/Dra/Afpb 18.01, License Amendment Request to Adopt NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) Project stage: RAI ML13296A5302013-10-23023 October 2013 NRR E-mail Capture - Callaway - Request for NFPA 805 License Amendment Factual Accuracy Review Project stage: Acceptance Review ML13246A3502013-10-31031 October 2013 NFPA-805 LAR F&O Table Project stage: Other ML13318A1222013-11-14014 November 2013 NRR E-mail Capture - FW: Callaway NFPA 805 LAR, Fpe RAI 20 Project stage: RAI ML13274A5962014-01-13013 January 2014 Issuance of Amendment No. 206, Adopt National Fire Protection Association Standard 805, Performance Based Standard for Fire Protection for LWR Generating Plants Project stage: Approval ML14045A2842014-02-14014 February 2014 Amendment 31 to License Renewal Application Regarding Fire Protection Project stage: Other 2012-07-12
[Table View] |
Fire Modeling Requests for Additional Information, Request to Adopt National Fire Protection Association Standard NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition)ML12159A111 |
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Callaway ![Ameren icon.png](/w/images/0/06/Ameren_icon.png) |
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Issue date: |
06/06/2012 |
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NRC/NRR/DRA/AFPB |
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To: |
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Hon A |
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ML12159A089 |
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References |
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TAC ME7046 |
Download: ML12159A111 (4) |
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Category:Request for Additional Information (RAI)
MONTHYEARML24066A1932024-03-0707 March 2024 2024 Callaway Plant Notification of Biennial Problem Identification and Resolution Inspection and Request for Information ML23200A2982023-07-19019 July 2023 NRR E-mail Capture - Callaway Plant, Unit 1 - Final Request for Additional Information (RAI) - Request for Approval of Oqam, Revision 36a - EPID L-2023-LLQ-0000 ML23174A1272023-06-23023 June 2023 Cw FFD Document Request List 2023 ML23158A1462023-06-13013 June 2023 Notification of Post-Approval Site Inspection for License Renewal and Request for Information Inspection (05000483/2023010) ML23163A1572023-06-0606 June 2023 In-service Inspection Request for Information ML23096A0072023-04-0505 April 2023 NRR E-mail Capture - Final Request for Additional Information - Callaway Plant, Unit 1 - License Amendment Request to Revise TS 5.5.16 for Permanent Extension of Integrated Leak Rate Testing - EPID L-2022-LLA-0165 ML23080A1382023-03-21021 March 2023 Notification of Inspection (NRC Inspection Report 05000483/2023003) and Request for Information ML23073A0262023-03-13013 March 2023 NRR E-mail Capture - Final - Request for Additional Information - Callaway Plant, Unit 1 - SG Inspection Report Review - EPID L-2022-LRO-0143 ML23037A7092023-02-0606 February 2023 April 2023 Emergency Preparedness Exercise Inspection - Request for Information ML23026A0212023-01-24024 January 2023 NRR E-mail Capture - Final - Request for Additional Information - Callaway Plant, Unit 1 - LAR for Proposed Changes to TS for SFP - ML22287A0952022-10-14014 October 2022 NRR E-mail Capture - Final - Request for Additional Information - Callaway Plant, Unit 1 - License Amendment Request for Adoption of Alternate Source Term and Revision of Technical Specifications - EPID L-2021-LLA-0177 ML22269A4312022-09-26026 September 2022 November 2022 Emergency Preparedness Program Inspection - Request for Information ML22173A0562022-06-22022 June 2022 Information Request, Security IR 2022402 ML22167A0252022-06-15015 June 2022 NRR E-mail Capture - Final - Request for Additional Information - Callaway Plant, Unit 1 - LAR for Proposed Revision to Radiological Emergency Response Plan Regarding Response & Notification Goals - EPID L-2022-LLA-0024 ML22157A0572022-06-0606 June 2022 Notification of NRC Design Bases Assurance Inspection (Programs) (05000483/2022013) and Request for Information ML22154A0122022-06-0202 June 2022 NRR E-mail Capture - Final - Request for Additional Information - Callaway Plant, Unit 1 - License Amendment Request for Adoption of Alternate Source Term and Revision of Technical Specifications - EPID L-2021-LLA-0177 ML22151A0512022-05-27027 May 2022 NRR E-mail Capture - Final - Request for Additional Information - Columbia Generating Station - LAR to Change TS 3.4.11 - Reactor Coolant System Pressure and Temperature Limits - EPID L-2021-LLA-0191 ML22137A0292022-05-16016 May 2022 NRR E-mail Capture - Draft - Request for Additional Information - Callaway Plant, Unit 1 - License Amendment Request for Adoption of Alternate Source Term and Revision of Technical Specifications - EPID L-2021-LLA-0177 ML22096A0232022-04-0505 April 2022 NRR E-mail Capture - Callaway Plant - Final RAIs - License Amendment and Regulatory Exemptions for a Risk-Informed Approach to Address Generic Safety Issue - 191 and Respond to GL 2004-02 (EPIDs L-2021-LLA-0059 and L-2021-LLE-0021) ML21336A6392021-12-0202 December 2021 .05 Sec Doc Request ML21319A0062021-11-30030 November 2021 Supplemental Information Needed for Acceptance of Requested Licensing Actions License Amendment Request for Adoption of Alternate Source Term and Revision of Technical Specifications ML21258A0382021-09-14014 September 2021 NRR E-mail Capture - Final - Request for Additional Information - Callaway, Unit 1 - LAR to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors- EPID L-2020-LLA-023 ML21159A2352021-06-17017 June 2021 Notification of NRC Triennial Heat Exchanger/Heat Sink Performance Inspection (05000483/2021003) and Request for Information ML21130A5882021-05-11011 May 2021 Supplemental Information Needed for Acceptance of Requested Licensing Actions to Adopt a Risk-Informed Approach to Address GSI-191 and Respond to Generic Letter 2004 02 ML21088A3872021-03-30030 March 2021 Notification of Evaluations of Changes, Tests, and Experiments Inspection (Inspection Report 05000483/2021002) and Request for Information ML21007A1622021-01-0606 January 2021 NRR E-mail Capture - Final - Request for Additional Information - (COVID-19) Callaway Plant, Unit 1 - Additional Request for Exemption from Specific Requirements of 10 CFR Part 26, Fitness for Duty Programs - EPID L-2021-LLE-0242 ML20203M3682020-07-21021 July 2020 NRR E-mail Capture - Draft Request for Additional Information - Callaway Plant, Unit 1 - License Amendment Request - Revision to Technical Specification (TS) 5.3.1 and Deletion of TS 5.3.1.1 and 5.3.1.2 - EPID L-2020-LLA-0046 ML20162A1882020-06-10010 June 2020 Request for Supporting Information for the Callaway SPRA Audit Review - Draft Supplement ML20280A5442020-03-25025 March 2020 Cwy 2020 PIR Request for Information ML20064B6582020-02-27027 February 2020 Second, Third, and Fourth Request for Information for Callaway Dba Teams Inspection 2020011 ML19317E6332019-11-13013 November 2019 Request for Supporting Information for the Callaway SPRA Audit Review ML19107A5152019-04-11011 April 2019 Cwy 2019410 RFI Cyber Security Gap ML19078A2932019-03-18018 March 2019 Notification of an NRC Triennial Fire Protection Baseline Inspection (NRC Inspection Report 05000483/2019010) and Request for Information ML19023A2032019-01-22022 January 2019 Notification of NRC Triennial Heat Sink Performance Inspection (05000483/2019001) and Request for Information ML19009A3442019-01-0909 January 2019 NRR E-mail Capture - Formal Release of RAIs Ref: Callaway Plant Class 1E LAR, L-2018-LLA-0062 ML18355A4882018-12-20020 December 2018 NRR E-mail Capture - Formal Release of RAI Ref: Callaway Plant EAL Changes, L-2018-LLA-0239 ML18331A2052018-11-27027 November 2018 NRR E-mail Capture - Formal Release of RAIs Ref: Callaway Relief Request EPID L-2018-LLR-0051 ML18025B4672018-01-24024 January 2018 NRR E-mail Capture - Request for Extension of Due Date for RAI Response ML17304B1912017-10-31031 October 2017 NRR E-mail Capture - Requests for Additional Information Concerning Callaway License Amendment - Thermal Overload Protection ML17142A1352017-05-19019 May 2017 Notification of NRC Design Bases Assurance Inspection (05000483/2017007) and Initial Request for Information ML17115A0622017-04-25025 April 2017 NRR E-mail Capture - Requests for Additional Information -- Callaway Plant, Unit 1, Technical Specification 5.6.5, Core Operating Limits Report CAC MF8463 ML17038A2292017-02-0707 February 2017 NRR E-mail Capture - RAI Formal Release for Callaway SG Tube Inspection Report, MF8474 ML16111B3222016-04-20020 April 2016 Notification of Evaluations of Changes, Tests, and Experiments, and Permanent Plant Modifications Inspection (05000483/2016007) and Request for Information ML15316A1532015-11-12012 November 2015 Request for Additional Information Email, Relief Request 13R-11 (Pressurizer Welds) from Code Case N-460 Requirements, Third 10-Year Inservice Inspection Interval ML15096A0942015-04-0606 April 2015 Notification of Inspection (NRC Inspection Report 05000483/2015003) and Request for Information ML14353A1172014-12-22022 December 2014 Request for Additional Information, Round 3, License Amendment Request to Revise Final Safety Analysis Report Standard Plant Section 3.6 for High Density Polyethylene (Hdpe) Crack Exclusion ML14294A7752014-10-28028 October 2014 Request for Additional Information, Round 2, License Amendment Request to Revise Final Safety Analysis Report Standard Plant Section 3.6 for High Density Polyethylene (Hdpe) Crack Exclusion ML14203A0632014-07-25025 July 2014 Request for Additional Information, Relief Request I3R-17, Proposed Alternative to ASME Code, Section XI Requirements, Which Extends Rv ISI Frequency from 10 to 20 Years, Third 10-Year ISI Interval ML14178A8232014-07-0101 July 2014 Request for Additional Information, License Amendment Request to Revise Final Safety Analysis Report- Standard Plant Section 3.6 for High Density Polyethylene (Hdpe) Crack Exclusion ULNRC-06117, Callaway Plant, Unit 1, License Revewal Application, Request for Additional Information (RAI) Set 31 Responses2014-04-24024 April 2014 Callaway Plant, Unit 1, License Revewal Application, Request for Additional Information (RAI) Set 31 Responses 2024-03-07
[Table view] |
Text
REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO ADOPT NATIONAL FIRE PROTECTION ASSOCIATION STANDARD 805 PERFORMANCE-BASED STANDARD FOR FIRE PROTECTION FOR LIGHT WATER REACTOR GENERATING PLANTS CALLAWAY PLANT (TAC NO. ME7046)
Office of Nuclear Reactor Regulation Division of Risk Assessment Fire Protection Branch Fire Modeling General Questions and Requests:
- In cases where conservative input parameters outside the validated range are used to obtain a safety margin, explain how it is ensured that this is not offset by increased model uncertainty?
- Some of the RAI responses state that specific documents on the portal (e.g. FDS Report, R1984-001-001) will be modified and corrected. It is requested that the updated documents be posted on the portal.
Fire Modeling RAI 1b - Additional Clarification Needed. To demonstrate that the models are applied within the range of applicability, the normalized parameters described in NUREG 1824 and 1934 were calculated and the calculations showed that the parameter is within the validated range or justification was provided for using a parameter value outside the validated range.
- Fire Froude Number: Explain in more detail how you determined quantitatively, the effect of using a conservative convection fraction of 0.7 on the safety margin in the plume ZOI calculation. In addition, describe the criteria that were used to judge that the margin of safety is sufficient.
- Ceiling Jet Radial Distance Relative to Ceiling Height: Provide the normalized parameter values and discuss in light of the sprinkler activation calculations.
- Compartment Aspect Ratio: Confirm that the correct damage temperature in each of the fire zones where the sensitivity analysis was conducted is in fact 330 °C and not 205 °C.
Fire Modeling RAI 1c - Additional Clarification Needed. To demonstrate that the models are applied within the range of applicability the normalized parameters described in NUREG 1824 and 1934 were calculated and either showed that the parameter is within the validated range or justification was provided for using a parameter value outside the validated range.
- Sprinkler Activation Correlation: Explain in more detail how the Ceiling Jet Distance Ratio normalized parameter was calculated. The draft response describes the r/H calculation used in the sensitivity analysis. Is the H equal to the distance between the floor and ceiling or the distance between the ignition source and the ceiling? In addition, for Fire Area A-16, explain in more detail how the 'critical heat release rate for sprinkler activation' was calculated in FDT 10.
Fire Modeling RAI 1e - Additional Documentation Required. Staff needs to review the report of the sensitivity study mentioned on page 11 of the draft response to confirm that it is acceptable for the Radial Distance Relative to Fire Diameter to be outside the validated range. The sensitivity analysis report needs to be posted on the portal.
Fire Modeling RAI 1f - Additional Clarification/Documentation Required.
- MCR Study: The justification for the flame length ratio normalized parameter is adequate, however, there is a confusing comment about the ACRS recently deciding that this parameter should be based not only on the flame height, but the height of the fire above the floor and that this is different from NUREG 1934. This is confusing, since the latest version of NUREG 1934 does include the base height as well as flame height in this normalized parameter. Review this last justification statement and consider whether it should be amended or stricken from the response.
- In addition, in the justification for the equivalence ratio (natural ventilation) normalized parameter being outside of the validation range for heat release rates higher than 312 kW, it is mentioned that a sensitivity study may be warranted, but none is provided in the response.
Since the natural ventilation cases with the highest heat release rate bins seem to be the worst-case in terms of the calculated evacuation times, it is requested that this sensitivity study be provided.
Fire Modeling RAI 1g - Statement and Justification Needed. If the results of the studies described in Appendices B, C and D of the V&V report were used in the analyses within their limits of applicability, a statement should be provided indicating so. If not, a statement should be provided indicating why not. In addition, the plume-HGL interaction study in Appendix B is based on calculations for a single ambient temperature (70°F), heat release rate (211 kW) and fire size (physical dimensions) and height. Provide justification for drawing generalized conclusions based solely on calculations for these input parameter values.
Fire Modeling RAI 1i - Additional Justification Needed. Reference is made in the draft response to NIST GCR 07-911 for V&V of Cleary's smoke detector algorithm, which is now implemented in FDS. The validation in this NIST report is based on three sets of experiments: UL 217 Tests, Room-Corridor-Room Fire Tests and NIST 'Performance of Home Smoke Alarms' Test Validation.
- i. UL 217 Tests: Page 24 of the NIST report states that the smoke (soot) yield of polystyrene was estimated as the average of the values in the literature for polystyrene and styrene. Ignoring the fact that the use of the average in itself is questionable, the SFPE Handbook gives soot yields for polystyrene and styrene as 0.135 and 0.177 g/g, respectively, leading an average of 0.156 g/g. This is approximately three times what was used in the analysis for fire area C-21. ii. Room-Corridor-Room Fire Test Validation: These experiments consisted of pool fire experiments with a mix of 75% heptane and 25% toluene. The SFPE Handbook lists soot yields for heptane and toluene (listed directly after benzene, but the draft response indicated it was not available) as 0.037 and 0.178 g/g, respectively. The validated soot yield used in these experiments was approximately 0.072 g/g, which is a little bit higher than the value used in the C-21 analysis (0.05 g/g). iii. NIST 'Performance of Home Smoke Alarms' Test Validation: As mentioned in the draft response, there is no validated range in this study that can be compared to the analysis in C-21.
In addition, the draft response has some discussion about the literature values of soot yield for polystyrene mattresses and gives the range of 0.056-0.227 g/g. However, the low and high limits of this range are for polyethylene and polyurethane, not polystyrene. The SFPE Handbook gives a range of soot yield for polystyrene foam of 0.18 - 0.21 g/g, which is much higher than was used in the analysis for fire area C-21. Provide additional justification for the validity of Cleary's algorithm implemented in FDS for a smoke yield of 0.05 g/g. In addition, explain how the use of a soot yield of 0.05 g/g is justified.
Fire Modeling RAI 1j - Additional Documentation Required. The draft response states that there is a discussion in the FDS report (R1984-001-001) about the verification of Pyrosim. However, Pyrosim is not mentioned in the report that is on the portal. Provide the revised FDS report on the portal that discusses Pyrosim or explain this discrepancy.
Fire Modeling RAI 2a - Additional Justification Needed. The intent of this RAI was for the licensee to discuss all of the relevant model output parameters described in Table 3-1 of NUREG 1824 (Table 4-1 of NUREG 1934), not just these three. Expand the response to include and justify (as applicable) all the relevant model output parameters described in Table 3-1 of NUREG 1824.
Fire Modeling RAI 2b - Additional Justification Needed. Provide additional explanation of why hot gas and smoke movement is not affected. During the audit walkdown, NRC staff observed numerous cable trays and other obstructions directly above and adjacent to the ignition source but still within the beam pocket. The calculations assume three cable trays stacked vertically above the fire source location. Provide a detailed explanation of why the additional obstructions are not expected to break up and delay the development of the plume/HGL necessary to activate a detector and/or sprinkler in the beam pocket. In addition, provide a description of the decision process and criteria used for omitting specific obstructions from the FDS analyses.
Fire Modeling RAI 3c - Additional Documentation Required: The draft response states that a sensitivity study was conducted for Mesh 1 in Fire Area C-1 to show that results of a 0.05-m mesh would yield the same conclusions as the 0.1-m mesh used in the original analysis.
Provide the grid sensitivity study on the portal.
Fire Modeling RAI 3e - Additional Documentation Required. The Heskestad/Bill equation and part of the text appear to be missing from the non-docketed section. Provide the missing information in the response.
Fire Modeling RAI 3f - Additional Clarification Required. The licensee stated that the difference in material properties does not significantly affect the thermal inertia and therefore this difference will not affect the results of the analysis. Provide justification for the statement "- the difference in the thermal inertia values is not significant".
Fire Modeling RAI 3h - Additional Justification Needed. The licensee's approach recognizes the fact that there is a trade-off between choosing a low vs. a high heat release rate. The former delays detector and sprinkler activation but also results in less damage. To be conservative a relatively high peak heat release rate (317 kW) and a relatively slow growth rate (8 min to peak heat release rate) were used. Explain why only these two values were used and why a different set of equally plausible values would not result in greater risk.
Fire Modeling RAI 3i - Additional Documentation Required. Part of the draft response between pages 1 and 2 appears to be missing. Provide the missing information in the response.
Fire Modeling RAI 3j - Additional Justification Needed. See action for RAI 3k response below.
Fire Modeling RAI 3k - Additional Justification Needed. In the FDS analysis of fire area C-21, a sprinkler head RTI of 130(ms) 0.5 was used based on NUREG-1805. This value was justified because standard response sprinklers have an RTI of 80(m-s) 1/2 or higher and the use of 130(m-s)1/2 is therefore conservative. The draft response refers to a NIST study, which is cited as the basis of the default values in NUREG 1805. However, the objective of that study was to compare four sprinkler activation models. Another study by the same author and published in Operation of Fire Protection Systems (special addition to the NFPA Handbook), shows that the typical range for standard response sprinkler RTIs is approximately 100-350(m-s) 1/2. Provide justification for the use of an RTI of 130(m-s) 1/2 in lieu of the more conservative values reported in the literature.
Fire Modeling RAI 3p - Additional Information Needed. The concern also included the possibility of HGL forming above the MCR cabinets, as they did not extend to the ceiling and also any other means of fire spread via the open ceiling area, not just cabinet-to-cabinet directly. Exposed cables, if any, could also be targets along which fire could propagate between the two areas.. The draft response discusses why direct cabinet-to-cabinet fire propagation is precluded, but does not discuss other potential modes of fire spread. Provide a discussion of other potential modes of fire spread in the response.