RS-10-041, Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time
| ML100700557 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 03/09/2010 |
| From: | Simpson P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RS-10-041 | |
| Download: ML100700557 (18) | |
Text
.,
Exelon.
Exelon Generation www.exeloncorp.com Euclear 4300 Winfield Road Nucear Warrenville, I L 60555 RS-10-041 10 CFR 50.90 March 9, 2010 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455
Subject:
Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time
References:
- 1. Letter from P. R. Simpson (Exelon Generation Company, LLC) to U,. S.
Nuclear Regulatory Commission, "License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time,"
dated September 24, 2009
- 2. Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S.
Nuclear Regulatory Commission, "Clarification Regarding License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time," dated November 13, 2009
- 3. Letter from M. J. David (U. S. Nuclear Regulatory Commission) to C. G. Pardee (Exelon Generation Company, LLC), "Byron Station, Unit Nos. 1 and 2 -
Request for Additional Information Related to One-Time Extension of Essential Service Water Train Completion Time (TAC Nos. ME2293 and ME2294),"
dated December 18, 2009
- 4. Letter from P. R. Simpson (Exelon Generation Company, LLC) to. U. S.
Nuclear Regulatory Commission, "Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time," dated January 19, 2010
- 5. Letter from M. J. David (U. S. Nuclear Regulatory Commission) to C. G. Pardee (Exelon Generation Company, LLC), "Byron Station, Unit Nos. 1 and 2 -
Request for Additional Information Related to One-Time Extension of Essential Service Water Train Completion Time (TAC Nos. ME2293 and ME2294),"
dated February 19, 2010 POO1
March 9, 2010 U. S. Nuclear Regulatory Commission Page 2
- 6. Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S.
Nuclear Regulatory Commission, "Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time," dated March 1,2010
- 7. Email from M. J. David (U. S. Nuclear Regulatory Commission) to P. R. Simpson (Exelon Generation Company, LLC), "Byron Station, Unit Nos. 1 and 2 - Request for Additional Information Related to One-Time Extension of Essential Service Water Train Completion Time (TAC Nos. ME2293 and ME2294)," dated February 26, 2010 In Reference 1, Exelon Generation Company, LLC, (EGC) requested a license amendment for Byron Station, Units 1 and 2, to revise Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.7.8, "Essential Service Water (SX) System," to extend the Completion Time (CT) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br />. This proposed change will only be used one time during the Byron Station Unit 2 spring 2010 refueling outage (i.e., B2R15) to restore a unit-specific SX train to operable status. In Reference 2, EGC supplemented the request to provide clarification regarding the inventory control function.
In Reference 3, the NRC requested that EGC provide additional information in support of their review of Reference 1 as supplemented by Reference 2. Reference 4 provided the requested information.
In Reference 5, the NRC requested that EGC provide additional information in support of their review of Reference 1 as supplemented by References 2 and 4. Reference 6 provided the requested information.
In Reference 7, the NRC requested that EGC provide additional information in support of their review of Reference 1 as supplemented by References 2, 4, and 6. Attachments 1, 2 and 3 of this submittal provide the requested information. Reference 7 requested that the response be submitted to the NRC by March 5, 2010. However, as documented in an email dated March 4, 2010, from Marshall David-of the NRC to Patrick Simpson of EGC, it was agreed that EGC would provide a response by March 9, 2010.
EGC has reviewed the information supporting a finding of no significant hazards consideration that was previously provided to the NRC in Reference 1 as supplemented by References 2, 4, and 6. The additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," paragraph (b),
a copy of this letter and attachments are being provided to the designated State of Illinois official.
The revised summary of compensatory measures for the Byron SX A train outage are summarized in a revised Table 3 in Attachment 2. This replaces the Table 3 provided in of Reference 1.
March 9, 2010 U. S. Nuclear Regulatory Commission Page 3 The regulatory commitments contained in this letter are summarized in Attachment 3 and supersede the commitment provided to the NRC in Reference 1. The regulatory commitments provided in Attachment 3 are in addition to the commitments previously provided to the NRC in References 4 and 6.
Should you have any questions concerning this letter, please contact Ms. Lisa A. Schofield at (630) 657-2815.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 9th day of March 2010.
Respectfully, Patrick R. Simpson Manager - Licensing Exelon Generation Company, LLC Attachments: 1. Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time
- 2. Revised Summary of Compensatory Measures
- 3. Summary of Regulatory Commitments
March 9, 2010 U. S. Nuclear Regulatory Commission Page 4 cc:
NRC Regional Administrator, Region III NRC Senior Resident Inspector, Byron Station NRR Project Manager, Byron Station Illinois Emergency Management Agency - Division of Nuclear Safety
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time In an email dated February 26, 2010, the NRC requested that Exelon Generation Company, LLC, (EGO) provide additional information related to the application for a one-time extension of the essential service water (SX) train Completion Time (CT). Attachments 1, 2 and 3 provide the requested information.
References:
- 1. Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S.
Nuclear Regulatory Commission, "License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time,"
dated September 24, 2009
- 2. Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S.
Nuclear Regulatory Commission, "Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time," dated January 19, 2010
- 3. Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S.
Nuclear Regulatory Commission, "Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time," dated March 1, 2010 Question 1:
Questions on the Commitments for Table 3 of Attachment 1 of the LAR:
(Ref: January 19, 2010, response to questions 3.c and 3.d) It is not clear what criteria was applied to identify the protected equipment or the fire zones to be subject to walkdowns, other than that risk insights were applied in some manner. A more specific definition of the criteria applied (e.g., top X cutsets, to Y% of risk, Fussel-Vessely or risk achievement worth values) needs to be identified for the NRC staff to conclude that the scope of the protected equipment and fire zones is adequate for tier 2 and for the compensatory measures.
(Ref: January 19, 2010, response to question 3.b) The response generally clarified the scope of the equipment which is protected, but this information needs to be included in a revised commitment reference. Specifically, the following items in Table 3 of Attachment 1 of the LAR are too vague and need to be formally clarified:
Unit 1 SATs - this should specifically refer to transformer SAT 142 which is protected Unit 2 SATs - this should specifically refer to transformer SAT 242 which is protected Unit 1 120 VAC Inst Inverters - this should specifically refer to the four inverters protected Page 1 of 9
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time In addition, the following aspects of Table 3 are confusing and should also be clarified as to exactly what the commitment entails:
Comment entry on 4KV Bus 142 regarding "minimize or preclude" breaker switching operations - need to clarify three items: 1) why is this comment applied only to this bus (i.e., not bus 141, 241, 242), 2) is the commitment to preclude or to minimize, and what is the meaning of "minimize" with regards to a license commitment?, and 3) does the comment add additional requirements beyond "protected equipment", or does it supersede "protected equipment"?
1 SX033/1 SX034 and 2SX033/2SX034 - clarify why separate components are on a single line entry - does this mean one or the other is protected, or both?
The entry for the fire zone walkdowns needs to clarify what is being committed with regards to "transient control" - it is assumed this means transient combustibles? Is the commitment that there will be no transient combustibles in the zone, or that they are simply stored properly, or something else? Does the commitment eliminate hot work in the zone (typical of licensees)?
Response to Question 1:
The list of equipment identified in the Internal Events column of Table 3, "Byron SX A Train Outage Summary of Compensatory Measures," of Attachment 1 of Reference 1 was not limited by the number of cutsets, % of risk, Fussell-Vesely, or risk achievement worth values. The list of identified equipment was based on a combined process, which included a review of the previous submittal for an SX CT extension dated June 11, 2003, and a review of the Unit 1 cutset results for the expected configuration of the 1 A and 2A SX pumps being unavailable.
EGC procedure WC-AA-101, "On-Line Work Control Process," was used in the development of the equipment contained in Table 3 (Internal Events Column).
The fire zones identified in Table 3 of Attachment 1 contain fire scenarios which are the highest fire risk scenarios in the CT extension configuration fire PRA quantification. The scenarios with compensatory actions specified represent 75% of the increase in CDF between the CT extension configuration and the baseline configuration. Therefore, the criterion was the top delta CDF scenarios including all scenarios that comprise 75% of the delta CDF.
The following clarifications are provided to Table 3 of Attachment 1 of Reference 1:
Unit 1 SATs specifically refers to transformers SAT 142-1 and SAT 142-2 Unit 2 SATs specifically refers to transformers SAT 242-1 and SAT 242-2 Unit 1 120VAC Inverters specifically refers to inverters 1IP11, 11P112, 11P113 and 11P114 Page 2 of 9
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time The words "Minimize or preclude breaker switching operations, especially for offsite power supply breakers" in the Comments column of Table 3 were deleted for Bus 142 and the Switchyard (see description below).
Both components, 1 SX033 and 1 SX034, (2SX033 and 2SX034) are protected. These valves, which comprise the train cross-tie function for the SX system, were listed on a single line entry for convenience. Separate line items were added to Table 3 for each component.
The qualitative description of the fire zones and focus areas as described in the response to Question 3.d in Reference 2 were added to the fire zones listed in Table 3.
The Fire column of Table 3 was identified as a risk source for Dedicated SX operators in addition to the Internal Events column. This change is to align Table 3 with Table 14, "Byron SX A Train Outage Summary of Compensatory Measures," of Attachment 5 of Reference 1.
The above clarifications are summarized in a revised Table 3 in Attachment 2 of this submittal.
This replaces the Table 3 provided in Attachment 1 of Reference 1. The compensatory measures in Table 3 are considered to be regulatory commitments and are summarized in. This commitment supersedes the commitment provided to the NRC in Reference 1. Reference Summary of Regulatory Commitments in Attachment 3.
At the time of the submittal of Reference 1, EGC guidance on the process controls associated with protected equipment was still in the developmental stage. On December 16, 2009, EGC guidance on the protection of equipment was issued in the form of procedure OP-AA-108-117, "Protected Equipment Program." In the response to Question 3 in Reference 2 regarding protected equipment controls, EGC committed to implement procedure OP-AA-1 08-117 at Byron Station prior to the Byron Unit 2 B2R1 5 refueling outage. The programmatic controls described in this procedure, including those described in sections 4.3.7 and 4.4.3, provide the guidance to address the aspect of breaker manipulation on the protected busses. With the commitment to implement OP-AA-1 08-117, the comment provided in Table 3 for Bus 142 and the switchyard (i.e.,."Minimize or preclude breaker switching operations, especially for offsite power supply breakers") is overridden by the programmatic controls in procedure OP-AA-1 08-117. A copy of OP-AA-1 08-117 was provided in Reference 2.
The commitment related to fire zones specifies that a walkdown of the identified fire zone will be performed prior to the initiation of maintenance work on the 1 (2)SX001A valves. The purpose of this walkdown is to insure that transient combustibles in the identified fire zones are within the administrative limits of the Byron Fire Protection program. Transient combustibles and hot work are controlled in accordance with existing Fire Protection programmatic requirements.
Page 3 of 9
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time However, EGC commits to the additional following actions beyond those specified in existing Fire Protection program procedures:
Prohibition of hot work in open areas within 35 feet of the focus area components in the Fire Zones listed in Table 3 in Attachment 2 of this submittal. The focus areas were described in the response to Question 3.d in Reference 2.
Establishment of a continuous fire watch for the Auxiliary Building general area fire zones 11.3-0, 11.4-0 and 11.6-0.
Removal of transient combustibles in open areas within 35 feet of the focus area components in the Fire Zones listed in Table 3 in Attachment 2 of this submittal.
Control of transient ignition sources (i.e., temporary cabling) in open areas within 35 feet of the focus area components in the Fire Zones listed in Table 3 in Attachment 2 of this submittal.
Reference Summary of Regulatory Commitments in Attachment 3.
Question 2:
Questions on the quality of the fire probabilistic risk assessment (Ref: January 19, 2010, response to question 1.b):
Item 5, regarding the lack of treatment of hot gas layers - the statement that, "A practical treatment of hot gas layer [HGL] formation is not yet available in industry" is not true, since there are simple Fire Dynamics Tools in NUREG-1805, "Fire Dynamics Tools (FDTs) Quantitative Fire Hazard Analysis Methods for the U.S. Nuclear Regulatory Commission Fire Protection Inspection Program," for example, which provide simple correlations for HGL formation. The statement that "...[HGL] formation is not expected to be a significant contributor to risk at a newer plant such as Byron with typically large volumes for dissipation... " is too vague for the NRC staff to rely upon as a justification that neglecting HGL formation is not ignoring potentially risk-significant scenarios. The licensee should examine the fire areas of their plant using available tools to confirm that HGL formation will not occur or will not be significant and provide a more robust justification.
Item 11, regarding the choice of a motor fire to represent a typical transient fire - if the most likely type of transient combustible is temporary cabling (as stated in the RAI response), then selection of the electric motor fire source (i.e., 32/69 kw at the 75th/98th percentile heat release rates in NUREG/CR-6850, EPRI TR-1 011989, "EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities") rather than electrical cabinet (i.e., 69/211 kw at the 75th/98th percentile heat release rates in NUREG/CR-6850) would seem more representative of the cited transient fire scenario. The basis for selecting a motor fire source instead needs to be justified.
Page 4 of 9
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time Response to Question 2:
To evaluate the potential impact of the unlikely hot gas layer fire scenario, a review was performed of the CDF quantification associated with an Appendix R fire impacting all components and cables within each fire zone. For zones in which more detailed scenarios were defined by postulating fires at specific fire ignition sources, the base zone quantification is not used in the fire PRA. However, the data from this baseline fire quantification provides a means for identifying those zones in which a hot gas layer causing extensive impact to components and cables in an area would result in a high CDF contribution. Table 1 summarizes the fire zones identified with high CDF consequences for an Appendix R type fire (a conservative bounding evaluation for a low likelihood hot gas layer impact).
Table 1 Fire Zones with Hiah CDF Conseauences for Aooendix R Fire Fire Zone Scenario Ignition Source Zone Description 11.5-0 A
Bounding Fire Auxiliary building general area, elev. 401 11.6-0.
A Bounding Fire Auxiliaryibuilding general area, elev. 426 51A BoundingFire
- Unit 1 auxiliary electric equipment room 11.3-0, A
Bounding' fire Auxiliary building general area, elev. 364 2.1-0 A
Bounding Fire Main control room
,ý5l11 A,
Bounding Fire Division 12 ESF swithgear room
- 11. 4-0' A'
Bounding Fire Auxiliary building general area, eley. 383' 5.4-1 A
Bounding Fire Division 12 miscellaneous electric equipment room and battery room 11.2-0 A
Bounding Fire Auxiliary building general area, elev. 346 11.4C-0 A
Bounding Fire Radwaste and remote shutdown panel control room 11.1 B-0 A
Bounding Fire Unit 2tauxiliary building basemeht"'
3.2B-1 A
Bounding Fire Unit 1 lower cable spreading room, zone B-1 3.2C-1 A
Bounding Fire Unit 1 lower cable spreading room, zone C-1 1,.3-1."
-A.
!Boundihg
'Fire Unit 1 containment pipe, penetration area' 3.2A-1 A
Bounding Fire Unit 1 non-segregated bus duct area 3.2D-1 A
Bounding Fire Lower cable spreading room, zone D-1 5.1-,1:-B B
1 AP06E (BUS 42)
DMv sion.12 ESF switchdgear roomn 3.3C-1 A
Bounding Fire Unit 1 upper cable spreading room, zone C-1 11.3-0--D D
1~AP23E(MCC132X1)
Auxiliairyfbuilding general area, elev. 364, 18.11-0 A
Bounding Fire River screen house 18.14A-1 A
Bounding Fire SX tower electrical equipment room, Division 12 5.4-2 A
Bounding Fire Division 22 miscellaneous electric equipment room and battery room Page 5 of 9
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time Table 1 Fire Zones with High CDF Consequences for Appendix R Fire Fire Zone Scenario Ignition Source Zone Description 5.3-1 A
Bounding-Fire Unit 1 non-ESF switchgear room 52-A
.ifBounding Fire Di'visin *1 ESF switclgear room,'
111'B-O-E E
1SX01PB SEVERE-FIRE
'Unit 2 aux iary biiildingba.sement',,"
,1.1 BiB *G
- G 2SX01 PB SEVERE FIRE Unit 2 auxiliarybuildingdbas'ement 11.6-1i~
A Bou6nding Fire
<Divisiorn 12 containment electrical penetratio'ns area 18.4-1 A
Bounding Fire Main control room HVAC equipment room, train A 11.6
- F.
Pi6E AND XFMR Auxiliary building general area, el#v. 426",
(SWGR 134X) 1.1.3-1-.
.B 1AP21E (M*C C1 31 X1)
Unit 1 containment pipe pernetration area 5.6-1 A
Bounding Fire Division 11 miscellaneous electric equipment room and battery room
.1.4-0-F F
1AF01 PA AND2AF01PA Auxiliary building general area, elev. 383 5.- -LL 1PA1JUnit 1 auxiliary' electric equipment room~
11.4-0-1B B
1AP24E (MCC132X3,).Auxliary building general area; elev.:383:
3.3D-1 A
Bounding Fire Unit 1 upper cable spreading room, zone D-1 11.5A-1 A
Bounding Fire Division 11 containment electrical penetrations area 5.2-,1-B B:'
l':j
.AP0SE (BUS 141))
Division
- *it ESF'switchgearroo.
The shaded rows in Table 1 are associated with the specific high CDF scenarios for which compensatory action has been specified in previous submittals associated with this LAR.
A review of the other areas defined additional administrative controls to reduce the likelihood of a hot gas layer impact.
The auxiliary building general areas comprise large volumes of the auxiliary building connected via an open stairwell to the remainder of the auxiliary building and therefore provide a very large volume not susceptible to hot gas layer formation for a high heat release electrical cabinet fire (bounding heat release rate fire given the limited combustible liquid in these areas). Therefore, no further evaluation of this large volume for hot gas layer impact is performed. The fire zones from Table 1 to which this screening applies are 11.2-0, 11.3-0, 11.4-0, 11.5-0, and 11.6-0.
These zones contain a volume of over 100,000 cubic feet each.
The normally manned main control room, fire zone 2.1-0, is addressed by the control room panel fires and control room abandonment analyses. The continuous manning of the control room makes the frequency of a significant fire, including a fire causing a hot gas layer impacting many control room components, highly unlikely.
Page 6 of 9
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time The floor areas and volumes associated with each zone for the other areas are compiled in Table 2.
Table 2 Floor Areas and Volumes Associated with Fire Zones Fire Zone Floor Area Volume Notes (square feet)
(cubic feet) 3.2A-1 4,891 48,910 10' high ceiling 3.2B-1 5,327 53,270 10' high ceiling 3.2C-1 2,803 28,030 10' high ceiling 3.2D-1 513 5,130 10' high ceiling 3.3C-1 2,698 26,980 10' high ceiling 3.3D-1 1,055 10,550 10' high ceiling 5.1-1 2,337 25,707 11' high ceiling 5.2-1 2,265 24,915 11' high ceiling 5.3-1 2,238 53,712 24' high ceiling 5.4-1 1,507 21,098 14' high ceiling 5.4-2 1,536 21,504 14' high ceiling 5.5-1 1,911 19,110 10' high ceiling 5.6-1 733 17,592 24' high ceiling 11.1 B-0 4,942 69,188 14' high ceiling 11.3-1 3,531 123,585 35' high ceiling 11.4C-0 3,509 56,144 16' high ceiling 11.5A-1 3,489 34,890 10' high ceiling 18.4-1 1,433 34,392 24' high ceiling 18.11-0 7,855 212,085 27' high ceiling 18.14A-1 574 10,906 19' high ceiling The fire zone from Table 2 with the smallest volume is zone 3.2D-1 with a volume of approximately 5,100 cubic feet. This zone contains only transient combustible ignition sources.
For this small volume, a large fire of 1,000 kW would require approximately 20 minutes to reach the damage temperature of IEEE-383 cabling. Limited ignition sources (primarily transient) in this zone and availability of detection and suppression systems along with manual fire response by the fire brigade will ensure that the likelihood of damage to cables due to a hot gas layer will be very small.
The zone with the smallest volume containing fixed ignition sources is zone 18.14A-1 with a volume of approximately 11,000 cubic feet. The time required for a hot gas layer in this fire zone to reach the damage temperature of IEEE-383 cabling is over 60 minutes. The likelihood of failure of fire brigade response within this timeframe is very small and therefore damage to cables due to a hot gas layer is unlikely.
Page 7 of 9
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time The above evaluations for hot gas layer impact are conservative in that they assume that a fire will last for the durations specified. In reality, NUREG/CR-6850 specifies a heatup rate of less than 15 minutes as opposed to the constant heat release rate at the conservative value of 1,000 kW assumed in the evaluation above.
Based on the above assessment, a hot gas layer fire in the fire zones of greatest potential CDF contribution during the SX CT is unlikely. However, to ensure that any such fire will be quickly identified, additional administrative controls have been defined to reduce the likelihood, of a hot gas layer impact. Specifically, EGC commits to maintain the fire detection systems for the Fire Zones listed in Table 2 for the duration of the extended SX completion time. In addition, the suppression systems installed in Fire Zones 3.2A-1, 3.2B-1, 3.2C-1, 3.2D-1, 3.3C-1, 3.3D-1, 11.3-1 and 18.11-0 will also be maintained available for the duration of the extended SX completion time. If a detection or suppression system (for the fire zones above) becomes unavailable, a continuous fire watch will be established for the impacted zone. Reference Summary of Regulatory Commitments in Attachment 3.
The heat release rate specified for evaluating transient fires in the Fire PRA is not the recommended value from Table E-1 of NUREG/CR-6850. A recent examination of the industry fire events that were counted to generate the transient fire frequency determined that the events that occurred following the implementation of Fire Protection programs in accordance with 10 CFR 50.48 are more accurately characterized as transient ignition sources. They were not transient combustible fires of the sizes and types that form the bases for the heat release rates specified in Table E-1 of NUREG/CR-6850. The specific range of transient ignition sources that were experienced and used to develop the fire frequency are best described as relatively benign events. For the purposes of the Fire PRA, it was concluded that the NUREG/CR-6850, Table E-1 recommended heat release rate for a large motor fire would represent a suitably conservative and bounding treatment. It is noted that the resulting heat release rate of 32 kW and 69 kW for the 75th and 98th percentile values, respectively, would be the applicable value for motors up to hundreds of horsepower. It was judged that this treatment would remain conservative and bounding given the actual events that occurred - extension cord, work lamp, space heater, etc.
The treatment of transient fires also considered the potential that a transient ignition source could be co-located with a transient combustible fuel package. In this case, the existence of the transient combustible fuel package was treated as an independent event. The probabilistic treatment of this combination considered the conditional probability of the presence of a transient combustible fuel package concurrent with the transient ignition source and the random nature of its specific location within the zone. It is noted that the first term in this treatment, the conditional probability of the presence of a transient combustible fuel package, has an inverse relationship with the floor area involved. As the floor area increases, the conditional likelihood would increase. The likelihood decreases for areas with a very small floor area; therefore, for a very small room, the likelihood should be considered negligible.
Page 8 of 9
ATTACHMENT 1 Additional Information Supporting License Amendment Request for a One-Time Extension of the Essential Service Water Train Completion Time When these factors are considered in an integrated fashion, four applicable factors are used:
the transient ignition source fire frequency, the conditional probability that the ignition source is near some cable target (the heat associated with the ignition source itself is unlikely to create a HGL condition without secondary ignition of cables), the likelihood that a transient combustible fuel package exists within the same fire zone at the time the fire occurs, and that conditional probability that the transient fuel package is located near enough to the ignition source that it becomes involved in the same fire. When these factors are combined for large rooms, their resultant combination results in extremely low values which easily justifies their exclusion from further treatment. For smaller rooms, larger values result but are still small as compared to the significant fire risk contributors. For example, if a room of 1,000 square feet is considered and a conservative exposure footprint of 100 square feet for the transient fire, the resultant factor is 0.01 for the ignition source and fuel package to be co-located. However, in a small room, the conditional probability that the fuel package would exist at the time of the fire should be less than unity. If a factor of 0.10 were considered together with a nominal transient ignition source fire frequency of about 1 E-4 and the prior area factor, their combination would result in a value on the order of 1 E-7. Although not insignificant, it is very low relative to the key fire risk contributors and therefore is not considered further.
Page 9 of 9
ATTACHMENT 2 Revised Summary of Compensatory Measures Table 3 Byron SX A Train Outage Summary of Compensatory Measures Risk Source Compensatory Measure Internal F
1 Comments Events Fire Shutdown Unit 0 CC Heat Exchanger x
x Protected Equipment (controlled in accordance with OP-AA-108-117)
Unit 2 CC Heat Exchanger X
X Unit 1 CC Heat Exchanger X
X 1 SX005 (crosstie MOV)
X 2SX005 (crosstie MOV)
X 1 B SX Pump X
X Monitor pump for fire precursor indicators 2B SX Pump X
X X
Monitor pump for fire 1 A_ AFPump__
precursor indicators 1A AF Pump X
1B AF Pump x
2A AF Pump X
SAT 142-2)
4KV Bus 142 X
Minimie Or. p rcude bre~kr W44Gh4Rg operations, especially 1Fo offeite poerupl 4KV Bus 241 X
4KV Bus 242 X
X Switchyard X
Minim-i-;ze. or prelud operations, espocially for offeite power supply 1 A E D G X
1B EDG X
2A EDG X
2B EDG X
X DC Battery & Charger 111 X
DC Battery & Charger 112 X
DC Battery & Charger 211 X
DC Battery & Charger 212 X
2B CV or 2B SI Pump 2A or 2B RH Pump x
2B CC Pump x
1SX0334SX-14 X
1 SX034 X
2SX033LQSX034 X
X 2SX034 X
X VA Supply Plenum X
VA Exhaust Plenum X
OA Fire Pump X
OB Fire Pumn x
Page 1 of 3
ATTACHMENT 2 Revised Summary of Compensatory Measures Table 3 Byron SX A Train Outage Summary of Compensatory Measures Risk Source Compensatory Measure Internal Comments Evnts Fire Shutdown Events 1A CV Pump Alt Cooling X
1 B CV Pump Alt Cooling X
Protected Unit 1 120 VAC Inst Inverters X
Equipment (1IP111, 11P112, 11Pl13 and (controlled in 11p1141 accordance Unit 1 SI signals X
Prohibit surveillance with OP-AA-testing on SSPS/ESFAS 108-117)
SI logic Fuel Pool Cooling - 1 train X
available Isolate one train of Unit 2 X
Improves effectiveness Equipment RCFCs of SX Unit Crosstie Alignment 1SX005 (or 2SX005) Open X
Improves effectiveness Aligmentof SX Unit Crosstie Changes Unit 1 CST Filled to 350,000 X
gallons Improves response to "Dedicated SX" operators X
X loss of remaining SX Pumps Not performed during reduced inventory or X
high decay heat levels 11.1 B-0 Unit 2 Prior to entrance into the auxiliary building X
SX completion time basement (SX B Train Pump Room) 11.3-0 auxiliary Prior to entrance into the building general area, X
SX completion time elev. 364 (focus on MCC 132X1 )
11.3-1 Unit 1 Prior to entrance into the containment pipe SX completion time Fot-Z-eAeINA D
penetration area X
F,....
o lk (focus on MCC donim for tranin 11X)
FiXre Zones 1) with Compensatory 11.4-0 auxiliary Prior to entrance into the Measures building general area, SX completion time elev. 383 (focus on X
1AF01PA, 2AF01PA and MCC 132X3) 11.6-0 auxiliary Prior to entrance into the building general area X
SX completion time elev. 426 (focus on SWGR 134X) 11.6-1 division 12 Prior to entrance into the containment X
SX completion time electrical penetration area Page 2 of 3
ATTACHMENT 2 Revised Summary of Compensatory Measures Table 3 Byron SX A Train Outage Summary of Compensatory Measures Risk Source Compensatory Measure Internal Fire Shutdown Comments Events 5.1-1 division 12 ESF Prior to entrance into the switchqear room SX completion time (focus on switchcear Firo Zone walk down 142) 5.2-1 division 11 ESF' Prior to entrance into the tr-lFire Zones (c
oniswitchqear room SX completion time with Compensatory 141 onswtcqa Measures i4_11 5.5-1 Unit 1 auxiliary Prior to entrance into the electrical equipment SX completion time room (focus on 1 PA23J.)
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ATTACHMENT 3 Summary of Regulatory Commitments The following table identifies commitments made in this document. (Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRC's information and are not regulatory commitments.)
T DCOMMITMENT TYPE COMMITMENT COMMITTED DATE OR ONE-TIME PROGRAMMATIC "OUTAGE" ACTION ACTION (Yes/No)
(Yes/No)
Implement the compensatory Upon implementation of measures listed in Attachment 2 of Uponeimemention RS-10-041, Table 3, "Byron SX A of the SX train Yes No Train Outage Summary of Completion Time.
Compensatory Measures."
Compl EGC commits to the following actions:
Prohibition of hot work in open areas within 35 feet of the focus area components in the Fire Zones listed in Attachment 2 of RS-10-041, Table 3, "Byron SX A Train Outage Summary of Compensatory Measures."
The focus areas were described in the response to Question 3.d in EGC letter dated January 19, 2010.
Establishment of a continuous fire watch for the Auxiliary Building general area fire zones 11.3-0, 11.4-0 and 11.6-0.
Removal of transient combustibles in open areas within 35 feet of the focus area components in the Fire Zones listed in Attachment 2 of RS-1 0-041, Table 3.
Control of transient ignition sources (i.e., temporary cabling) in open areas within 35 feet of the focus area components in the Fire Zones listed in Attachment 2 of RS-10-041, Table 3.
Upon implementation of the one-time extension of the SX train Completion Time.
Yes No Page 1 of 2
ATTACHMENT 3 Summary of Regulatory Commitments COMMITMENT TYPE COMMITMENT COMMITTED DATE OR ONE-TIME PROGRAMMATIC "OUTAGE" ACTION ACTION (Yes/No)
(Yes/No)
EGC commits to maintain the fire detection systems for the Fire Zones listed in Table 2 in of RS-10-041 for the duration of the extended SX completion time. In addition, the suppression systems installed in Upon implementation of Fire Zones 3.2A-1, 3.2B-1, 3.2C-1, the one-time extension Ye 3.2D-1,3.3C-1, 3.3D-1, 11.3-1 and of the SX train Yes No 18.11-0 will also be maintained ofpt e
tin available for the duration of the Completion Time.
extended SX completion time. If a detection or suppression system (for the fire zones above) becomes unavailable, a continuous fire watch will be established for the impacted zone.
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