L-2014-256, Response to Request for Additional Information Re License Amendment Request No. 216 - Transition to 10CF50.48(c) - NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants
| ML14279A093 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 09/12/2014 |
| From: | Kiley M Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML14279A176 | List: |
| References | |
| L-2014-256 | |
| Download: ML14279A093 (11) | |
Text
Florida Power & Light Company 9760 SW 344 St Homestead, FL 33035 0 September 12, 2014 IPLo L-2014-256 10 CFR 2.390 10 CFR 50.90 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555-0001 Re: Turkey Point Nuclear Generating Station Units 3 and 4 Docket Nos. 50-250 and 50-251 Response to Request for Additional Information Regarding License Amendment Request No. 216 - Transition to 10 CFR 50.48(c) - NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition)
References:
- 1. Florida Power & Light Company letter L-2012-092, "Transition to 10 CFR 50.48(c) -
NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition), June 28, 2012.
- 2. NRC letter, Audrey Klett to Mano Nazar, Turkey Point Nuclear Generating Unit Nos. 3 and 4 - Request for Additional Information on License Amendment Request to Adopt National Fire Protection Association Standard 805 Performance Based Standard for Fire Protection (TACs ME8990 and ME8991), dated June 14, 2014 ADAMS Accession No. ML14083A377.
- 3. Florida Power & Light Company letter L-2014-197, "Response to Request for Additional Information Regarding License Amendment Request No. 216 - Transition to 10 CFR 50.48(c) - NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition), July 18, 2014.
- 4. Florida Power & Light Company letter L-2014-071, "Response to Request for Additional Information Regarding License Amendment Request No. 216 - Transition to 10 CFR 50.48(c) - NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition), April 4, 2014.
By Florida Power & Light Company (FPL) letter L-2012-092 dated June 28, 2012, (Reference 1) in accordance with the provisions of 10 CFR 50.90, "Application of License or Construction Permit," FPL requested an amendment to the Renewed Facility Operating License (RFOL) for Turkey Point Nuclear Generating Station Units 3 and 4. The License Amendment Request (LAR) will enable FPL to adopt a new fire protection licensing basis which complies with the requirements in 10 CFR 50.48(a) and (c) and the guidance in Revision 1 of Regulatory Guide (RG) 1.205.
On July 14, 2014, the NRC Staff requested additional information regarding the LAR (Reference 2). By FPL letter L-2014-197 dated July 18, 2014 (Reference 3), Turkey Point provided the response in part to the requests for additional information (RAIs) that involved clarifications of Security-Related Information - Withhold From Public Disclosure Under 10 CFR 2.390. M 4-kL Enclosures 1, 2, and 3 to this letter contain security-related information. Upon removal of Enclosures 1, 2, and 3, this letter is uncontrolled.
L-2014-256 Page 2 of 2 Turkey Point Probabilistic Risk Assessment (PRA) methodology. The attachment to this letter provides the response to the remaining RAIs.
The final risk estimates based on the methodology summarized in the RAI responses documented by FPL letters L-2014-197 (Reference 3), L-2014-071 (Reference 4), and the attachment to this letter are provided in Enclosure 1 to this letter, the updated LAR Attachment W, "Fire Risk Insights." Enclosure1 to this letter supersedes LAR Attachment W originally submitted to the NRC by Reference 1. The updated LAR Attachment W demonstrates that the total delta risk and fire area delta risk do not exceed the acceptance guidelines of Regulatory Guide 1.174. to this letter provides a mark-up of LAR Attachment C, Table C-2, "NFPA 805 Required Fire Protection Systems and Features," originally submitted to the NRC by Reference 1. Enclosure 3 to this letter provides a mark-up of LAR Attachment G, Table G-1, "Recovery Actions and Activities Occurring at the Primary Control Station," originally submitted to the NRC by Reference 1. Revisions to LAR Attachment C, Table C-2, and LAR Attachment G, Table G-1 reflect conforming changes as a result of the final quantification. Enclosures 2 and 3 to this letter supersede LAR Attachment C, Table C-2 and LAR Attachment G, Table G-1, originally submitted to the NRC by Reference 1.
Enclosures 1, 2, and 3 to this letter contain sensitive Security-Related Information; therefore, FPL requests that they be withheld from public disclosure in accordance with 10 CFR 2.390.
The additional information provided in this letter does not impact the 10 CFR 50.92 evaluation of "No Significant Hazards Consideration" previously provided in FPL letter L-2012-092. This letter does not add any new commitments.
If you should have any questions regarding this application, please contact Robert Tomonto, Licensing Manager, at 305-246-7327.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on September 12, 2014.
Michael Kiley Vice President Turkey Point Nuclear Generating Station Attachment and Enclosures cc: Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point USNRC Project Manager for Turkey Point Ms. Cindy Becker, Florida Department of Health Security-Related Information -Withhold From Public Disclosure Under 10 CFR 2.390.
Enclosures 1, 2, and 3 to this letter contain Security-Related Information. Upon removal of Enclosures 1, 2, and 3, this letter is uncontrolled.
Attachment to L-2014-256 Page 1 of 9 L-2014-256 Attachment Response to Request for Additional Information Regarding License Amendment Request No. 216 Florida Power & Light Company Turkey Point Nuclear Generating Station Units 3 and 4 Transition to 10 CFR 50.48(c) - NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants, 2001 Edition
Attachment to L-2014-256 Page 2 of 9 PTN PRA RAI 07.01 .c.01 The April 4, 2014, response to PRA RAI 07.01 .c states that "panels of 440 V [volts] or greater
( ... ] are not assumed to propagate a fire outside[ ... ] consistent with the guidance of NUREG/CR-6850 [ ... ]." Associated guidance in Frequently Asked Question 08-0042 from Supplement 1 of NUREG/CR-6850 applies to electrical cabinets below 440 V. With respect to Bin 15 as discussed in Chapter 6, it clarifies the meaning of "robustly- or well-sealed" when used in conjunction with these lower voltage cabinets. For those cabinets of 440 V and higher, the original guidance in Chapter 6 remains: "Also note that panels that house circuit voltages of 440 V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)." Therefore, propagation of fire outside the ignition source panel must be evaluated for Bin 15 panels that house circuits of 440 volts or greater. Clarify whether the fire PRA used to support the final composite analysis and post-transition will be updated to incorporate the analysis and modeling changes described in the response to PRA RAI 07.01, but also including an evaluation about fire propagation outside of Bin 15 panels that house circuits of 440 V or greater in accordance with accepted guidance as summarized above.
RESPONSE
PRA RAI 07.01.c.01 requests clarification that the Fire PRA used to support the final composite analysis and post transition will be updated to incorporate the analysis and modeling changes described in the response to PRA RAI 07.01 including the evaluation of fire propagation outside of Bin 15 panels that house circuits of 440 V or greater. The final composite Fire PRA and the Fire PRA used to support the post transition will include the analysis and model changes as described in the response to PRA RAI 07.01 and include fire propagation from Bin 15 panels housing circuits > 440V as described below.
The treatment described here applies only to Motor Control Centers (MCCs) operating at greater than 440 V that meet the criteria in FAQ 08-0042 for being well-sealed and robustly secured. The treatment of postulated fires originating at well-sealed (robustly sealed) MCCs followed the guidance in NUREG/CR-6850 as modified by FAQ 08-0042 (see NUREG/CR-6850 Supplement 1 Section 8). From an overall perspective, the guidance provided in FAQ 08-0042 identifies two attributes to be considered. Those two attributes are the adequacy of the sealing of openings and the robustness of the door attachments. FAQ 08-0042 provides criteria and discussions to address these issues. However, there is some inconsistency in the interpretation of this guidance for the propagation of fires outside of Bin 15 panels operating at > 440 V. This inconsistency is reflected in Turkey Point PRA RAI 07.01.c.01. This RAI requests additional information regarding the behavior and risk implications of the treatment of well-sealed, robustly secured MCCs operating at 440VAC or higher as capable of propagating a fire to external targets. The RAI refers to wording in Chapter 6 of NUREG/CR-6850 that states that panels housing circuit voltages of 440V or higher should be counted because an arcing fault could compromise panel integrity.
In order to address this RAI, additional details and methodological treatment are necessary beyond that already published in NUREG/CR-6850 or the Supplement. Fire PRA FAQ 14-009 was issued by the industry to obtain clarification for the fire propagation from well-sealed, robustly secured MCCs>440V. Since the FAQ has not been resolved as of the date of the RAI response, Turkey Point proposes the following to address this RAI. A two factor approach will be used to address the arcing fires that propagate:
Attachment to L-2014-256 Page 3 of 9 F= FE x FB Where F = fraction of fires that propagate from well-sealed, robustly secured MCCs and damage targets outside the MCC FE = ratio of 440V fires that are energetic enough to breach the cubicle FB = fraction of fires impacting a target above the MCC (based on fire modeling)
Given that a fire has occurred in an MCC, it is not realistic nor appropriate to assume that all such events would be capable of breaching an otherwise well-sealed, robustly secured enclosure. In order to address this consideration, it is necessary to consider empirical evidence from industry fire events.
A report prepared by an independent panel was used to support the review for this response (1)
The NRC formal response to the panel report also did not identify any technical flaw or error in the results (2)
The independent panel assessment (')found:
- The total number of MCC fire events included in the set used to generate the generic fire frequency was 53 o Eight (8) events were excluded from further consideration in the Panel Factor Report so as to not dilute the results by inflating the denominator of the fraction being generated o 21 events were assigned a weight of 0.50 for determination of the total population count
-o 24 events were assigned a weight of 1.0 for determination of the total population count o The net of the above is an event count of 34.5 which represents the denominator of a fraction
- The 45 events with a non-zero population weight were reviewed o Of the events with a counting weight of 0.50, one (1) had an assigned factor of 0.50 (net count of 0.25) o Of the events with a counting weight of 1.0, two (2) had an assigned factor of 0.50 (net count of 1.0), and five (5) had an assigned factor of 1.0, for a net count of 5.0 o This results in only eight (8) events to be examined to determine if there was evidence that it could have breached an otherwise well-sealed, robustly secured enclosure
- To determine the factor FE, the event descriptions and summary of review notes, generated from the review summarized above and documented in the references cited above, were reviewed for the eight (8) events noted above o Events 2314 and 2336 each had a counting weight of 1.0 and had clear evidence that the enclosure was breached. For event 2314, the nature of the event was such that a breach would have occurred regardless of the robustness of the enclosure. For event 2336, the event description included a narrative using the words "door had blown open". These two events yield a cumulative count of 2.0.
Attachment to L-2014-256 Page 4 of 9 o Events 177 and 1135 each had a counting weight of 1.0 but were inconclusive and were conservatively assigned a value of 0.50 yielding a total count of 1.0.
o The remaining four events (events 74, 324, 534, and 1276), had no indications that an energetic event had occurred nor was there any indication that the event compromised the MCC enclosure and are therefore not counted.
o The net of above is a count of 3.0 A simple ratio of the events that breached or could have breached the enclosure versus the total number of events yields a factor for FE of 0.087 (3.0/34.5).
Based on the assessment presented above, a fire frequency modification factor of 0.087 can be used to treat the fraction of MCC fire events that are assumed to be capable of breaching an otherwise robustly secured enclosure. This assessment is conservative since it presumes that all fires were associated with well-sealed, robustly secured MCCs when some of the events are likely to be associated with non-well sealed MCCs. Given that a postulated fire scenario has breached a well-sealed, robustly secured enclosure, fire modeling can then be applied to treat the fire scenario.
A simplified and bounding fire model for thermoplastic cable targets was developed using the plume centerline temperature correlation from NUREG-1 805. This model was applied using the NUREG/CR-6850, Appendix E, Table E-4 heat release rate probability distribution applicable to an MCC (per NUREG/CR-6850, Appendix G, p. G-25, including Figures G-6 and G-7). A fire with a characteristic surface area of 3 ft 2 (based on an MCC cubicle stack characteristic dimensions of 1.5 ft wide by 2 ft deep) was used with a cable tray target assumed to be located 6" above the top of the MCC. The MCC was assumed to be configured to have four equal sized cubicles in a stack each 18 inches tall. The fire in each cubicle was assumed to be located at the horizontal centerline of the cubicle. The first cubicle fire was assumed to be located at a distance of 1.75 ft below the cable tray (6" between top of MCC and cable tray, 6" wireway at the top of the MCC and 9" distance from top of the cubicle to the center of the cubicle). Each subsequent assumed cubicle fire was assumed to be 18" below the location of the fire of the cubicle above it. This resulted in four cases to be evaluated for the MCC stack. For each assumed cubicle fire, the required heat release rate (HRR) to cause the plume centerline temperature at the cable tray location to be equal to the thermoplastic cable damage temperature (205 0C) was determined. The severity factor associated with the HRR was then determined using the Gamma distribution parameters from NUREG/CR-6850, Table E-4. This was repeated for each of the assumed cubicle fires. The resulting four severity factor values were then weighted by 0.25 to reflect the equal likelihood of fire occurrence and then summed to obtain an aggregate effective severity factor for the entire MCC stack. The resulting aggregate severity factor, FB, of 0.45 represents the fraction of MCC fires that could damage an overhead target located 6 inches above the top given that it had already breached the enclosure
- caused an otherwise well-sealed, robustly secured enclosure to become 'open'. This 0.45 severity factor is then combined with the previously calculated 0.087 term to yield a value for F of 0.039.
Attachment to L-2014-256 Page 5 of 9 The Turkey Point Fire PRA quantifications have been updated to reflect the treatment of well-sealed, robustly secured MCCs operating at 440V or higher as being capable of breaching their enclosure. This updated treatment used a value of 0.10 which bounds the 0.039 term presented above. This factor reflects the probability that a fire will propagate beyond the boundary of a sealed MCC and will result in damage to a cable tray located 6" above the top of the MCC. The 0.1 factor was applied in the updated quantification as a bounding value to be used while the specific value of this factor was being developed.
The results of this updated treatment are provided in the revised LAR Attachment W (Enclosure 1 to this letter). The use of the 0.10 bounding value was applied to facilitate the evaluation while the above analysis was developed. For future analyses further fire modeling may be employed to refine the FB factor under the NFPA 805 post transition fire protection program including self-approval.
REFERENCES
- 1. B. Bradley, NEI, to D. Harrison, NRC, Recent Fire PRA Methods Review Panel Decision:
Treatment of Electrical Cabinets, June 4, 2012
- 2. J. Guitter, NRC, to B. Bradley, Recent Fire PRA Methods Review Panel Decisions and EPRI 1022993, "Evaluation of Peak Heat Release Rates in Electrical Cabinet Fires",
June 21, 2012, ML12171A583
Attachment to L-2014-256 Page 6 of 9 PTN PRA RAI 11.01.c.01 The April 4, 2014, response to RAI PRA 11.01 .c did not provide the requested frequencies for the fire-induced main control room (MCR) abandonment scenarios. The results of the delta-risk evaluation for MCR abandonment documented in the license amendment request and experience from other NFPA-805 reviews indicate that the assumption about the probability of failing to successfully shutdown after MCR abandonment is a key assumption that can directly impact the regulatory decision. To support resolution of this key assumption, provide the requested MCR abandonment frequency for the compliant case, and for each of the three variant case bins developed from the final composite analysis.
RESPONSE
The results of the Control Room abandonment analysis based on the final model quantification, addressing all outstanding RAI issues (see RAI 29.c.01 for a discussion of the resolution of the various methodology-related RAIs), is provided below (the format is based on the initial version of the response to PRA RAI 11.01.c.01 provided on July 18, 2014).
Calculated CCDP Bin (CCDP Total Abandonment CCDP Range Value Used in Frequency of Associated Establishing Scenarios (per year) -
Total Variant applicable to the variant Risk) case as well as the corresponding compliant case Unit 3 < 1E-03 0.1 5.6E-05
< 0.1, 0.2 1.3E-06
> 1 E-03
> 0.1 1.0 1.8E-06 Unit 4 < iE-03 0.1 5.3E-05
< 0.1, 0.2 2.E-06
> 1E-03
> 0.1 1.0 2.3E-06 PTN PRA RAI 13.01.c.01 The April 4, 2014, response to PRA RAI 13.01.c states that the methods used for evaluating ACDF and ALERF, "provide a conservative bounding analysis of the delta risk." An overestimate of the compliant plant risk, unless offset with a similar overestimate in the variant plant risk, results in a non-conservative analysis of the delta risk. The method applied to the cable spreading room described in the response to RAI 13.01 .a and summarized below applies different assumptions to the variant and the compliant plant risk estimates with an indeterminate but most likely non-conservative impact on the change in risk estimate.
Attachment to L-2014-256 Page 7 of 9 The March 18, 2013, response to PRA RAI 13 states that "[tihere are no outside control room fires which result in the loss of sufficient control room control capabilities to warrant control room abandonment. For a control room fire, control room abandonment results from habitability (temperature and visual impact of the fire)." The response to PRA RAI 13 discusses cable spreading room fires and states that following fires in this area, the plant will be shut down using the MCR and assisted by primary control station (PCS) actions as needed. Nevertheless, PRA RAI 13.01 states that cable-spreading room fire "scenarios with variant-case CCDP [conditional core damage probability] >0.056 (...) used 0.056 as the compliant case CCDP." The 0.056 value was developed to characterize the failure to shut down using only a single, least reliable train and after MCR abandonment. This approach sets the variance from deterministic requirements (VFDR) delta risk to zero for all scenarios having a variant-case CCDP less than 0.056. Hence, this approach, and any similar approach that essentially sets to zero the delta risk for scenarios impacting VFDRs (e.g., assuming such impact only for hot gas layer (HGL) scenarios), is non-conservative for the delta risk. There appears to be no reason to use worst case MCR abandonment CCDP for every fire in the cable spreading room that doesn't always fail all equipment but the least reliable train, and that doesn't require the operator to abandon the MCR. In general, compliant case CCDPs for the cable room fires should be smaller than the worst case MCR abandonment CCDP. Apparently the variant case CCDP has been estimated (to know whether it is greater than 0.056), and the accepted method of removing variations from deterministic requirement failures from the variant case models to represent the compliant plant could be applied. An alternative is to not credit MCR abandonment due to loss of control and resolve VFDRs in the compliant case (e.g., set associated recovery actions in the variant case to successful). Provide a change in risk estimate that is not indeterminately non conservative.
RESPONSE
The compliant case CCDP was re-calculated based on credit for equipment available at the alternate shutdown panel (ASP) with equipment failures only applied to these components (to conservatively assume a human error probability, HEP, of zero). Components required to support the operation of the components at the ASP, which are not currently available at the ASP, were also credited based on equipment failures only and an assumed HEP of zero. This approach provides a compliant case risk for the control room abandonment assuming all required actions can be performed at the primary control station (i.e., the ASP), consistent with guidance of RG 1.205, Rev. 1.
Since the control room abandonment procedures credit offsite power, if available, restoration of offsite power at the ASP was also assumed based on equipment failures only and an HEP of zero. Although the ASP design is not intended to ensure the availability of offsite power, this approach is included to provide a more realistic estimate of the compliant case CCDP and reduce potential non-conservative delta risk estimates.
Variant case fire scenarios where the CCDP is less than this compliant case CCDP are considered to be sufficiently low to not require control room abandonment, and will therefore not contribute to the delta risk. The variant case for these scenarios are included in the total risk based on shutdown from the control room.
The above methodology was applied and the compliant case CCDP was calculated as 0.0517.
Using this CCDP and the above methodology, the delta risk for the cable spreading room was calculated as:
Attachment to L-2014-256 Page 8 of 9 Delta CDF Unit 3 - 1.43E-05 per year Unit 4 - 1.21 E-05 per year Delta LERF Unit 3 - 1.38E-06 per year Unit 4 - 1.23E-06 per year PTN PRA RAI 29.c.
By letter dated February 10, 2014, in PRA RAI 29.a, the NRC staff requested the licensee to indicate how it will address the use of unacceptable methods identified in previous RAI responses in its final composite analysis results. By letter dated April 4, 2014, the licensee responded to this RAI. The response to RAI 29.a in "Attachment to L-2014-071" included a Table (i.e., the Table) on pages 92 to 96. The Table included one column labeled, "Issue," one labeled, "Final composite Analysis Disposition," and one labeled, "Post Transition PRA Disposition." The "Issue" column referenced the RAI number that raised the issue.
In this RAI letter, the NRC staff is requesting additional information about seven of the RAI responses in the Table. The NRC staff is also requesting in this RAI letter additional information related to the April 4, 2014, responses to RAls 18.01 and 29.b that were not included in the Table.
- i. By August 15, 2014, please update and provide the Table to address the proposed resolution of the RAls requested in this letter.
ii. By August 15, 2014, provide final risk estimates (i.e., the CDF, LERF, ACDF, and ALERF, and additional risk of recovery actions) based on a PRA that uses only acceptable methods as summarized in the response to RAI 29.c.i for any method that affects the transition change in risk estimates. Discuss the likelihood that the risk increase in any individual fire area would exceed the acceptance guidelines and, if so, why exceeding the guidelines should be acceptable.
Attachment to L-2014-256 Page 9 of 9
RESPONSE
29.c.i The following table supplements the table provided in the response to PRA RAI 29.a on April 4, 2014 and incorporates the revisions to the table provided in the July 18, 2014 response to PRA RAI 01 .j.01.01 and PRA RAI 01 .t.01.01, to address the current set of RAIs.
Issue Final Composite Post Transition PRA Analysis Disposition Disposition PRA RAI 01 .j.01I01 .j.01.01 Confirmation of uncertainty analysis Given the SOKC calculations show regarding the state-of-knowledge mean value consistent with the point minimal difference between the correlation (SOKC) treatment in value used. mean and point values, the point post-transition fire risk evaluations / values will be used to judge whether use of point value versus mean the change meets the self-approval value for evaluation of risk against guidelines.
acceptance criteria SOKC calculations will be performed following each model update to verify minimal variance between the mean and point values 01.k.01 - Joint HEP (JHEP) floor Applied 1 E-05 JHEP floor value 1 E-05 JHEP floor value will be value applied. If use of a lower JHEP value is used in the future the basis for its use will be incorporated in the associated HRA documentation.
01 .r.02.c.01 - control room panel Basis for current analysis provided Basis will be used in post transition fire propagation in RAI response, model.
01.t.01.01 regarding replacement of Eliminated panel factors and The post transition fire PRA model panel factors with a new fire incorporated use of NUREGICR- will be the final composite analysis scenario development methodology 6850, Appendix H. model which has been updated to instead of acceptable methods. incorporate the analysis and modeling changes described in the response to PRA RAI 01.t.01.
07.01.c.01 - robustly sealed > 440 Methodology described in the Methodology described in the V panel fire propagation response to RAI 07.01 c.01 has response to RAI 07.01.c.01 will be been used in the final quantification. used in the post transition model.
11.01 .c.01 - MCR abandonment Data provided in response to this Data provided in response to this frequencies RAI is the data used in the final RAI will be used in the post quantification, transition quantification.
13.01.c.01 - Cable spreading room The method outlined in response to The method outlined in response to variant, compliant and delta risk this RAI is the basis for the final this RAI is also the basis for the calculation basis quantification, post transition quantification.
18.01.01 - Transient controls review Characterization of violations during Characterization of violations during power operation were provided. No power operation were provided. No change to quantification, change to quantification.
29.b.01 - RCP seal mod credit The credit defined by the response The credit defined by the response to this RAI is used in the final to this RAI will be used in the post quantification. transition model. Validation of this model against the final seal design configuration will be performed per specified NFPA 805 LAR Attachment S commitment prior to transition.
29.c.ii The final quantification is provided in Enclosure 1 to this letter, Updated LAR Attachment W, Fire Risk Insights. The updated LAR Attachment W demonstrates that the total risk and fire area risk (CDF, LERF, delta CDF and delta LERF) do not exceed the acceptance guidelines of Regulatory Guide 1.174.