2CAN050303, Emergency Diesel Generator (EDG) Allowed Outage Time (AOT) Request for Additional Information (RAI) Response
| ML031630524 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/06/2003 |
| From: | Millar D Entergy Operations |
| To: | Alexion T NRC/NRR/DLPM/LPD4 |
| Alexion T W, NRR/DLPM, 415-1326 | |
| Shared Package | |
| ML031600489 | List: |
| References | |
| 2CAN050303 | |
| Download: ML031630524 (24) | |
Text
F Thomas Alexion - ANO-2 Draft EDO AOT RAI Response Paae From:
To:
Date:
Subject:
"MILLAR, DANA <DMILLAR@entergycom>
- 'Thomas Aleion' <TWA@nrc.gov>
5/6/03 6:04PM ANO-2 Draft EDG AOT RAI Response
- Tom, Attached is a draft copy of the ANO-2 EDG AOT RAI Response. Please let me know when you and the appropriate reviewers are available to discuss the response via telephone and I will coordinate with ANO to get the needed participants.
- Thanks, Dana Millar Entergy 601-368-5445 CC:
- BENNETT, STEVE A' <SBENNE2@entergy.com>, BURFORD, FRANCIS Go
<FBURFOR @entergy.com>, LLOYD, MICHAEL' MLLOYD @entergy.com>, ROBINSON, THOMAS D
<TROBINS@ entergy.com>, FOUTS, DANIEL Wm DFOUTS @entergy.com>
Paae I Thornas Alexion - ANO-2 Draft EDG AOT RAI Response
F Thomas Alexion - 2can050303.doc Paoe 1 2CAN050303 May 14,2003 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Arkansas Nuclear One, Unit 2 Docket No. 50-368 Supplement to Amendment Request Related to the Extension of Emergency Diesel Generator Allowable Outage Time
REFERENCES:
- 1. Letter to the NRC dated September 19, 2002, License Amendment Request for Extension of Emergency Diesel Generator Allowable Outage Time (2CAN090202)
- 2. Letter to the NRC dated January 8, 2003, Supplement to Amendment Request for Extension of Emergency Diesel Generator Allowable Outage Time (2CAN01 0303)
Dear Sir or Madam:
By letter (Reference 1), Entergy Operations, Inc. (Entergy) proposed a change to the Arkansas Nuclear One, Unit 2 (ANO-2) Technical Specifications (TSs) to extend the emergency diesel generator allowable outage time. Entergy also responded to a related Request for Additional Information (RAI) by leter dated January 8, 2003 (Reference 2)
On January 21, 2003 Entergy received two additional questions that required formal response. Entergy's response is contained in Attachment 1.
Minor changes are proposed to one of the marked up TS pages, one of the marked up TS Bases pages, and two of the commitments submitted in Reference 1. New markups are provided for the affected TS page and TS bases page in Attachment 2. The attached commitment summary (Attachment 3) supercedes those presented In Reference 1.
Clarifications are made to commitments 2 and 4.
New commitments, which are also reflected In Attachment 3, are contained In this letter.
There are no technical changes proposed.
The original no significant hazards considerations included in reference 1 s not affected by any Information contained In this supplemental letter.
I you have any questions or require additional information, please contact Dana Millar at 601-368-5445.
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I Thomas Alexion - 2can0503-3-d-
-ao-2CAN050303 Page 2 of 2 I declare under penalty of perjury that the foregoing Is true and correct. Executed on May 14,2003.
Sincerely, Sherrie R. Cotton, Director, Nuclear Safety Assurance SRC/dm Attachments:
- 1. Response to Request for Additional Information
- 2. Proposed Technical Specification and Technical Specification Bases Pages (Markup)
- 3. List of Regulatory Commftments cc:
Mr. Ellis Merschoff Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 NRC Senior Resident Inspector Arkansas Nuclear One P. 0. Box 310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Mr. Thomas W. Alexion MS O-7D1 Washington, DC 20555-0001 Mr. Bemard R. Bevill Director DMsion of Radiation Control and Emergency Management Arkansas Department of Health 4815 West Markham Street Little Rock, AR 72205 I Thomas Alexion - 2canO50303.doc Paoe
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Attachment I To 2CAN05Q303 Response to Request for Additional Information Related to the Extension of Emergency Diesel Generator Allowable Outage Time I Thornas Alexion - 2canO50303.dox Paae
I Thomas Alexion - 2can050303.doc Page' Response to Request for Additional Information Related to the Extension of Emergency Diesel Generator Allowable Outage Time Question #1:
Please describe the methodology used to generate the extemat events risk numbers, including the final numbers generated for each extemal event If aspects of the extemal events analysis approach used in this application are substantially different from the methods described in previous recent applications (e.g., the power uprate application), please explain and justify the use of the different approach.
Response #1:
The Arkansas Nuclear One, Unit 2 (ANO-2) PSA model does not address the risk associated with extemal events, such as seismic events, intemal fires, and other extemal events (i.e., high winds, external flooding, and accidents involving nearby industries, transportation, and military facilities). Nor does this model address the risk associated with several other risk contributors, namely Anticipated Transients Without Scram (ATWS) scenarios, Interfacing System Loss of Coolant Accidents (ISLOCAs), and High and Medium Energy Une Breaks (HELBs and MELBs).
Qualitative analyses were performed to assess the risk impact of these non-modeled events on extending the current emergency diesel generator (EDG) allowable outage time (AOT). These analyses are considered qualitative since they are relatively simplistic and not based on comprehensive and detailed fault tree/event tree models. The Intent of these methods and results was to provide an order-of-magnitude assessment of the risk associated with these risk contributors.
Both the rnethodology and the numerical risk results generated via this methodology are presented below. These results were reported to the NRC by letter dated September 19, 2002 2CAN090202). A comparison of these methods with those used in the ANO-2 Power Uprate application also follows.
ATWS, ISLOCA, HELB and MELB Risk The nominal core damage frequency (CDF) contributions associated with ATWS and ISLOCA were documented in the ANO-2 Individual Plant Examination (IPE) as reported to the NRC by letter dated August 28, 1992 (2CAN089201).
The ATWS CDF estimate was subsequently updated. The nominal ATWS CDF and the nominal ISLOCA CDF are reported In Table 1-1, below. Nominal CDF contributions associated with HELB and MELB had not been estimated prior to the EDG AOT extension submittal.
The effect of removing an EDG from service on ATWS and ISLOCA contributions to CDF was assumed to be proportional to that of the modeled portion of the intemal events, since neither was judged to have a unique adverse effect on the EDGs or Alternate AC Diesel Generator (AACDG). The risk impact of the EDG AOT extension due to preventative maintenance (PM) on the ATWS and ISLOCA events Is provided in Table 1-1, below.
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ThomasAexion - 2can50303.doc Page to 2CAN050303 Page5 of 10 Table 1-1 ICDF (rx-vr)
I HELB contributions to risk were assumed to be bounded by the main steam line break (MSLB) risk which is Included in the ANO-2 PSA model. This assumption is based on a review of the High Energy Pipe Break Outside of Containment as described In the ANO-2 Safety Analysis Report (SAR) Section 3.6.4.1. Per this SAR section, none of the postulated HELBs resulted In both safety system actuation and the loss or partial loss of an actuated safety system. Thus, the risk associated with a MSLB outside of containment, which results in a plant trip and the concurrent loss of main feedwater (MFW), Is expected to be a first order estimate of the HELB risk impact. In addition, the MELB risk Impact is assumed to be bounded by the HELB risk impact. Since the CDF associated with the MSLB outside of containment is a small contributor (1.211 E-08) to the nominal ANO-2 CDF, the risk associated with HELB and MELS are expected to be negligible.
Seismic Events Risk A seismic vulnerability analysis using a modified Seismic Margins Assessment (SMA) methodology was performed as part of the ANO-2 Individual Plant Examination for Extemal Events (IPEEE) analysis and the results of this analysis were reported to the NRC by letter dated May 31, 1996 (0CAN059609). The analysis focused on verifying the seismic adequacy of equipment, tanks, distribution systems, structures, and relays at ANO-2. A 0.3g Review Level Earthquake (RLE) was used as a screening value in the analysis. If a component failed below this screening value, a High Confidence Low Probability of Failure (HCLPF) was calculated for the component. The HCLPF lowest ground acceleration was assessed to be 0.20g (for the EDG fuel tanks). It should be noted that the ANO-2 Design Basis Earthquake, a hypothetical earthquake with an intensity exceeding any expected to be felt at the site, Is also 0.2g, per Section 2.6.2 of ANO-2 SAR.
Other ANO-2 components reviewed for seismic vulnerability were expected to survive the 0.3g RLE.
Using general correlations between the magnitude of ground acceleration and the resulting damage to typical structures, it is conservatively assumed that ANO-2 will experience an unrecoverable loss of offsite power for ground accelerations greater than 0.05g (switchyard damage and/or transmission line damage can be expected). Based on this correlation and the expected relative ruggedness of the AACDG, its support systems, and its housing structure, it is assumed that the AACDG will be available for ground accelerations up to 0.15g. Also, based on the ANO-2 IPEEE seismic vulnerability analysis, t is assumed that ground acceleration greater than 0.2g will result in the loss of both EDGs. Ground acceleration greater than 0.3g was assumed to resuft in the loss of al offsite and onsite power, and the loss of steam-driven emergency feedwater (EFW) Train A; thus, the 0.3g event Is assumed to lead directly to core damage.
Using the above information, the impact of various seismic magnitudes is summarized In Table Contributor Nominal 2K-4A PM 2K.4B PM Modeled
&326E-06 1.020E-05 1.020E-05 Internal Events I
ATWS 1.590E-06 1.948E-06 1.948E-06 ISLOCA 3.270E-07 4.006E-07 4.006E-07
I Thomas Alexion - 2can050303.doc Paoe E Attachment I to 2CAN050303 Page 6 of 10 1-2, below. Per this table, only earthquakes 2 0.15g and < 0.2g have an effect on the risk associated with an extended EDG AOT. Earthquakes of magnitude < 0.05g were eliminated as significant risk contributors on the basis that they do not adversely affect the availability of plant equipment. Earthquakes of a magnitude greater than or equal to 0.05g and less than 0.15g were eliminated as significant risk contributors because they resuft only In the loss of offsite power (i.e., they do not adversely affect the EDGs or AACDG) and have a low frequency relative to the loss of offsite power (LOSP) nitiator (%T3), i.e., vomg (7E.4/rx-yr) cc vaosp (hT3
= 3E-2Jrx-yr).
Table 1-2 Seismic a < 0.05g 0.05g:s a <
0.15g s a O.2g s a 03g a 20.3g Magnftude,a
.15g 0.2g --
Offsite Power Available Unavailable Unavailabte Unavailable Unavailable AACDG Available Available Unavailable Unavailable, Unavailable EDGs Available Available Available Unavailable Unavailable EFW Train A Available Available Available Available Unavailable Effect on Risk No Impact Negligible Impact No impact, No impact associated with Impact, since assessment since both Extended EDG vog (7E-41rx-required EDGs are AOT yr) <c vLw (3E-assumed to fail 2/rx-yr) regardless of maintenance.
Using Electric Power Research InstKute (EPRI) NP-6395-D, the mean frequency of an earthquake in the range 0.15g to 0.2g at ANO-2 was estimated to be 4.84E-5yr. This value was calculated by averaging the logi frequencies associated with the 0.15g and 02g frequencies.
The CDF associated with an earthquake in this range was estimated by quantifying the intemal events ANO-2 PSA model. In the model, It was assumed that the effect of the loss of offsite power iniiator was representative of the effect of the seismic event and that an earthquake in the range 0.15g to 0.2g was most representative of the risk impact of an EDG AOT extension. In addition, for an earthquake in this range, both offsite power and the AACDG were assumed to fail.
The risk impact of the EDG AOT extension on seismic risk s provided in Table 1-3.
Table 1-3 ICDF (/irx-yr)
Contributor Nominal 2K-4A PM 2K-4B PM Modeled E.326E-06 1.020E-05 1.020E-05 Intemal Events Seismic 2.003E-07 1.324E-06 1.324E-06 Internal Fires Risk A fire vulnerability analysis using the NRC-approved Fire Induced Vulnerability Evaluation (FIVE) methodology was performed as part of the ANO-2 IPEEE analysis and the resuits of this analysis were reported to the NRC by letter dated May 31, 1996 (OCAND59609). These results were subsequently updated by letter to the NRC dated June 28, 2001 (2CAN060110) as part of Entergy's response to the ANO-2 Power Uprate submittal.
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I Thomas Alexion - 2can050303.doc Paie to 2CAN050303 Page 7 of 10 The ANO-2 IPEEE analysis for the risk associated with intemal fires dentified no ntemal fire vulnerabilities at ANO-2.
A single CDF associated with intemal fires was not provided.
However, a CDF for Individual fire zones was reported ff they were above 1 E-6rx-yr. Because the fire analysis was a screening analysis, these fire zone CDF values are expected to be conservatively high estimates. For the qualitative assessment of the risk impact of the ANO-2 EDG AOT extension, 1E-6/rx-yr was assumed to be the nominal value for the CDF associated with intemal fires. This value was used because the fire analysis was believed to be very conservative and the nominal fire CDF was believed to be a small fraction of the intemal events CDF and of the same order of magnitude as the ntemal flooding CDF.
For the current qualitative analysis, the ratio of the EDG out of service (OOS) CDF to the nominal CDF for intemal fires was assumed to be proportional to that associated with the intemal events CDF. These ntemal events CDF ratios are shown in Table 1-4.
Table 1-4 CDF (/rx-yr)
Contributor Nominal 2K4A PM 2K-4B PM Modeled 8.326E-06 1.020E-05 1.020E-05 Internal Events Intemal Fire 1.000E.06 1.225E-06 1.225E-06 High Winds Risk The ANO-2 IPEEE addressed the risk associated with high winds, Including tomadoes, and concluded that high winds do not pose a significant threat to the safe operation of the ANO-2 plant. The estimated CDF associated with high winds was less than 1E-6Jrx-yr. It should be noted that high winds distant from the ANO se and high winds at the site swXchyard could resuit in the loss of offsite power, however, this effect is already accounted for in the intemal events loss of offsite power initiator frequency. The qualitative assessment of the risk impact of the ANO-2 EDG AOT extension assumed the nominal value for the CDF associated with high winds was I E-61rx-yr.
The IPEEE analysis dentified only one issue that could disproportionally affect the high winds risk of extending the EDG AOT: the possible failure of the diesel generator exhaust stacks due to tornado missile perforation damage or due to high wind loading. The former was dismissed in the IPEEE since a missile large enough to crush or block the flow of exhaust gases was considered incredible.
This element of risk Is further reduced by the fact that operating procedures require inspection of the diesel stacks immediately after a tomado event and Initiation of corrective action to clear exhaust stack damage as quickly as possible.
Thus, for the current qualitative analysis, the ratio of the EDG OOS CDF to the nominal CDF for high winds was assumed to be proportional to that associated with the intemal events CDF.
The risk impact of the EDG AOT extension on the high winds risk is provided in Table 1-5.
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-e-to 2CAN050303 Page 8 of 10 Table 1-5 CDF (kx-yr)
Contributor Nominal 2K-4A PM 2K-4B PM Modeled 8.326E-06 1.020E-05 1.020E-05 Intemal Events High Winds 1.000E-06 1.225E-06 1.225E-06 External Floods Risk The ANO-2 IPEEE analysis for the risk associated with extemal flooding Identified no extemal flooding vulnerabilities on ANO-2. As such, the ANO-2 extemal flood CDF was assumed to be negligible.
Risk Due to Accidents Involving Nearby Industries, Transportation, and Military Facilities The ANO-2 IPEEE analysis for the risk associated with accidents involving nearby Industries, transportation, and military facilities identified no vulnerabilities to these accidents at ANO-2.
As such, the CDF associated with these accidents was assumed to be negligible..
Summary of Qualitative ATWS, ISLOCA, HELB, MELB and External Risk Results*
Table 1-6, below, summarizes the qualitative CDF results for the ATWS, ISLOCA, HELB, MELB and extemal risk contributors.
Table 1-6 These results were used to generate the Incremental conditional core damage probability (ICCDP) and Annual Average ACDF associated with the EDO AOT extension. The ICCDP for each of the EDGs was calculated as follows:
ICCDP = (14 days/365 daysyr) * (7.347E - 06/yr - 5.117E - 061yr)
= 8.6E -8 CDF (/rx-vr)
Contributor Nominal 2K-4A PM 2K-4B PM ATWS 1.590E-06 1.948E-06 1.948E-06 ISLOCA 3.270E.07 4.006E-07 4.006E-07 Seismic 2.003E-07 1.324E-06 1.324E-06 Intemal 1.OOOE-06 1.225E-06 1225E-06 Floods Intemal Fire 1.000E-06 1.225E-06 1.225E-06 HiQh Winds 1.OOOE-06 1.225E-06 1.225E-06 Total Non-5.1 17E-06 7.347E-06 7.347E-06 Modeled I Thornas Alexion - 2canO50303.doc Paae
[Thomas Alexion - 2can050303.doc Paoe
Atachment 1 to 2CAN050303 Page 9 of 10 The Annual Average ACDF for each of the EDGs and for both are calculated as follows:
Annual Average CDF for EDGA = (ICCDP for EDGAY1.5
= 5.7E-8/rx -yr Annual Average CDF for EDGB = (ICCDP for EDGB/1.5
= 5.7E -8Jrx -yr Annual Average CDF for EDGA & B = ((ICCDP for EDGA) + ( ICCDP for EDGB)/1.S
= 1.1E-7/nx - yr These ICCDP and Annual Average &CDF values are summarized In Tables 1-7 and 1-E, below, and are those reported to the NRC by letter dated September 19, 2002 (2CAN090202).
Table 1-7 Non-Modeled I ICCDP AOT (d) 2K-4A PM I 2K-4B PM 14 8.6E-08 I 8.6E-08 Table 1-8 Non-Modeled Yearly AOT Risk (Irx-yr)
AOT d) 2K-4A&B PM 14 1.1 E-07 Comparison of External Events Risk Analysis Methods With the exception of the fire risk, the qualitative methods employed to assess the impact of the EDG AOT extension on extemal events risk are generally consistent with those employed in the ANO-2 Power Uprate application (Letter submitted to the NRC dated June 28, 2001 (2CAND601 10)). The scope of extemal events risk analyses associated with the EDG AOT Extension and the Power Uprate submittals were similar. Both Investigated the effect of the submital on intemal fire, seismic, high winds and tomadoes, extemal flooding, and transportation and nearby facility accidents. The EDG AOT extension risk assessment also included the risk associated with HELBs and MELBs. Numerical values for the external risk contributors were generated in the EDG AOT extension submittal; the Power Uprate submtal generated numerical results only for the intemal fire extemal event, since the power uprate was assessed to have a negligible impact on all of the other external risk contributors.
The fire risk assessment employed in the ANO-2 Power Uprate submittal was more detailed than that employed in the ANO-2 EDG AOT extension submittal. The former reviewed the cutset results generated for each of the unscreened fire zones and revised each to account for increased operator failure probabilities due to the decreased time available for action at the uprated power conditions. The ANO-2 EDG AOT extension, as described above, assumed that the nominal value for the CDF associated with intemal fires was I E-6/rx-yr. It assumed that the increase in the internal fire CDF due to the EDG AOT extension was proportional to the increase in the intemal events CDF.
The simplistic approach used for the ANO-2 EDG AOT extension risk analysis was based on the conservative nature of the ANO-2 fire risk analysis. The existing ANO-2 fire analysis was
[ Thomas Alexion - 2canO5D303.doc Page
- Thma Alexion-ae i to 2CAN050303 Page 10 of 10 based on the EPRI FIVE methodology as documented n EPRI TR-100370s. This rnethodology is a vulnerability analysis, not a risk analysis. As such, t was not intended to produce a detailed quantification of fire CDF, but rather, to identify those plant areas/zones that might represent important fire CDF contributors. Based on the belief that the existing ANO-2 fire CDF results were very conservative, It was assumed that a more realistic treatment would show that the actual ANO-2 fire risk was a small facton of the ntemal events CDF and of the same order of magnitude as the intemal flooding CDF.
Consistent with Its expected relatively small contribution to the overall plant risk, the approach used to assess the impact of the EDG AOT extension was also simplistic. The Increase in fire risk was assumed proportional to the increase in the internal fire risk due to the AOT extension.
Question #2:
For the fire analyses, as an atemative to ustifying the use of a dfflerent approach discussed In Question 1 above, the licensee could describe how this application would impact each of the unscreened fire quadrant analyses and results identified In the June 28, 2001, letter to the U.S.
Nuclear Regulatory Commission (NRC) regarding its power uprate application. The NRC staff notes that in this letter, the licensee identlied 17 unscreened fire quadrants nvolving 15 fire areas and provided the associated post-uprate core damage frequency for each quadrant.
Response #2:
The fire portion of the ANO-2 IPEEE response as previously stated was performed using the EPRI FIVE Methodology as documented in EPRI TR-100370s.
The introduction to EPRI Report TR-100370s states, 'FIVE Is oriented toward uncovering limiting plant design or operating characteristics (vulnerabilities) that make certain fire-initiated events more likely than others." The FIVE methodology Is not a fire risk analysis, but a fire vulnerability analysis; as such, it produces a conservatively high screening estimate, not a best-estimate value, for the CDF for each fire zone. The CDF of each of the significant fire compartments (i.e., those with a CDF > 1 E-6/rx-yr) was compared to the closure guidelines provided in Section 4.3 of NEI 91-04, Revision 1, 'Severe Accident Issue Closure Guidelines, dated December 1994. Closure was obtained individually on each significant fire compartment.
This perspective on the conservative nature of the FIVE methodology and on the conservative nature of its CDF results is discussed by the Staff in its draft version of NUREG-1742, Vol.1,
'Perspectives Gained from the Individual Plant Examination of Extemal Events (IPEEE)
Program," dated April 2001 (Draft Report for Public Comment). In Section 3.4.1 of the report, it was noted that FIVE... is largely equivalent to a fire area/zone screening analysis. it is not intended to produce a detailed quantification of fire CDF, but rather, to identify those plant areas/zones that might represent important fire CDF contributors.' Section 1.3 of the report notes the following: IPEEEs are Intended to yield predominantly qualitative perspectives, rather than more quantitative findings."
Section 3.3 urther elaborates that although 'CDF Is the primary measure of fire-induced plant risk that emerges from the IPEEE fire analyses... the direct comparison of absolute CDF results was not generally considered to be appropriate..."
Section 3A.1 states that the perception that FIVE Is generally a conservative approach In comparison to fire PRA methods appears to be confirmed when the total CDF for various methodologies are compared.... Those submittals based solely on FIVE, in general, reported larger fire-induced CDF results than the submittals that used other methods.'
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Thomas Alexion - 2can050303.doc Page 11 to 2CAN050303 Page 11 of 10 The conservative nature of the FIVE methodology described in NUREG-1742 applies to the ANO-2 fire analysis. The ANO-2 IPEEE fire analysis was performed via a series of screening analyses of the various zones. The first of these screenings assumed failure of all components in the zone and components wth cables (i.e., power, control, or instrumentation cables) in the zone. Any zone not screened using this approach was identified for further analysis. This additional analysis nvotved identifying the dominant failures in each unscreened zone. For each unscreened zone, these dominant failures were Individually assessed to determine whether a fire would Indeed have failed the component of interest. If a determination was made that a component would not be affected by a fire in the zone, the zone was requantified with the component set to its nominal failure value. Iterations were performed on the unscreened zones until they screened or until the CDF for the zone was reduced to some frequency that was deemed to be acceptable. Potential fire vulnerabilities were identified based on the unscreened zones. Since the iterations on the unscreened zones were concluded when the intent of GL 20 was met, CDF results are not Indicative of a true fire risk. Thus, the conservative nature of the ANO-2 FIVE-based fire analysis and conservatisms used in this analysis make it inappropriate to make a direct comparison of the sum of the fire zone CDFs with the Regulatory Guide 1.177 and 1.174 risk acceptance guidelines.. Instead, t Is more appropriate to use the fire risk results to gain risk management insights that can be used to lower plant risk.
A review of the fire risk contributors was performed to obtain risk management insights that can be used to lower plant risk, especially during the EDG AOT condition.
This review was conducted using the fire risk results reported to the NRC by letter dated June 28, 2001 (2CAN0601 10), as part of our response to the ANO-2 Power Uprate submittal. The CDFs for the unscreened fire zones post power uprate are provided in Table 2-1, below.
Table 2-1 Fire FiTre Description CDF Area Zone (F-2)
N/A N/A Translormer Yard 1.09E-06 B
1B3SC Aux Bldq Ext 1.25E-06 SS 2097.X East DC Equip Room 1.85E-06 HH 2096-M MCC2B63 Room 1.90E-06 G
2098-C New CPC Room 1.92E-06 G
2199-G Control Room 2.00E-06 HH 2063SC Aux Bldg el. 354 1.97E-06 1I 2101-AA North Switchgear Room 2.45E-06 SS 2100 Z South Switchgear Room 3.90E-06 EE 2055SC Lower South Elect/Piping Penet Rm 5.44E-06 TT 2108-S Electrical Equipment Room 7.62E-06 JJ 2109-U Diesel Corridor 1.68E-06 JJ 2109-U Diesel Corridor - failure of 2 rows of 9.22E-06 2B51 00 IS Intake Structure 1.22E-05 G
2098-L Cable Spreading Room 1.69E-05 B
B5 Turbine Bldg A1/A2/CST Not Failed 3.43E-06 B
B5 Turbine Bldg A1/A2/CST Failed 3.66E-05 Upon review of the contributors to fire ntiation In the unscreened fire zones, several areas were identified as being most risk sensitive. These zones/areas include: the Turbine Building (B/B5), Transformer Yard, South Switchgear Room (SS/2100-Z), Cable Spreading Room I Thomas Aexion - 2canO50303.doc Pane 1
L6Thoas Alexion - 2can050303.doc Page 12 Attachment I to 2CAN050303 Page 12 of 10 (G/2098-L), Intake Structure (OOIS), Diesel Corridor (JJ12109-U), Lower South Elect/Piping Penetration Room (EE/2055SC), and Electrical Equipment Room (T12108-S). The Impact on fire risk in these zones can be managed as described below.
Turbine Building (BIBS)
The 2A1/2A2J2A9 switchgear area In the turbine building is the most risk sensitWe area In the turbine building because offsite power is provided via the 2A1 and 2A2 switchgear and power from the AACDG Is provided via the 2A9 switchgear. Fires of greatest risk importance are those that cause the loss of all three switchgear, especially fires that occur when an EDG Is out of service (OOS). The probability of fire risk In the turbine building in vicinity of 2AI12A212A9 switchgear can be reduced during the EDG outage by controlling transient fire combustibles and welding, and assigning continuous fire watches to this area. The consequence of a fire In this area will be determined by the size and location of the fire. The consequences can be reduced by providing a crew brief to the ANO-2 Operations personnel as well as the ANO-1 fire brigade members who are on shift during the EDG outage. The brief will include refresher information related to fighting electrical fires, relevant industry experience, and steps for restoration if a fire were to occur.
Transformer Yard Plant risk Is sensitive to a fire In the transformer:yard fire areatfire zone. This insight Is a result of the fact that all offsite power is provided to the plant through the transformer yard. Fires of greatest risk importance are those that cause the loss of power from both Startup Transformer No. 3 and Startup Transformer No. 2, especially fires that occur when an EDG is OOS. Startup Transformer No. 3 is in the ANO-2 transformer yard while Startup Transformer No. 2 is in the ANO-1 transformer yard. The two transformer yards are physically separated. The probability of a fire risk in this area can be reduced during an EDG outage by minimizing work in this area, including the control of welding and of transient combustibles.
Prior to an EDG outage the consequences of fire risk can be reduced by confirming the operability of the fire suppression In the transformer yard. This will be accomplished by verifying the surveillances are current and the system is not isolated. If the system is isolated, then fire hoses will be staged to the transformer yard area during the EDG maintenance outage. As part of the crew brief to ANO-2 Operations personnel and ANO-1 fire brigade members, refresher information related to fighting fires in the transformer yard will be provided also.
South Switchgear Room (SS/2100Z)
Plant risk Is sensitive, although to a lesser extent, to a fire in fire areaffire zone SS12100-Z (South Switchgear Room), especially fires that occur when an EDG is OOS. Again, the fire risk in this area can be reduced by controlling transient combustibles and welding.
Cable Spreading Room (G/2098-L), Intake Structure, Diesel Corridor (JJ/2109-U), Lower South ElectlPiping Penetration Room (EE/2055SC), and Electrical Equlpment Room (TT12108-S)
The removal of an EDG rom service does not affect the calculated fire risk associated wfth these areas. However, actions which reduce the fire risk in these areas, especially when an EDG is OOS, significantly reduce the overall plant fire risk. These actions include controlling
ThomasAlexion - 2canO50303.doc Page 1 Attachment I to 2CAN050303 Page 13 of 10 welding and transient fire combustibles In these areas during the EDG outage.
In conclusion, although the current version of the ANO-2 IPEEE fire risk results Is believed to conservatively overestimate the risk of fires at ANO, insights obtained from this analysis will be used to manage the fire risk so t is minimized when an EDG Is removed from service.
I Thma~Aleion---------------~ae 2CAN050303 Proposed Technical Specification and Technical Specification Bases Pages (Markup)
I Thomas Alexion - 2canO50303.doc Paae 14
I Thomas Alexion - 2can050303.doc rage 1
314.8 ELECTRICAL POWER SYSTEMS 3/4.8.1 A.C. SOURCES LIMITING CONDITION FOR OPERATION
- b. With one diesel generator of the above required A.C. electrical power source inoperable, perform the following:
- 1.
Demonstrate the OPERABIUTY of both the offsite A.C. circuits by performing Surveillance Requirement 4.8.1.1.1.a within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter, and
- 2.
Demonstrate the OPERABILITY of the remaining OPERABLE diesel generator by within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by:
- i.
Determining the OPERABLE diesel generator is not inoperable due to a common cause failure, or ii. Perform Surveillance Requirement 4.8.1.1.2.a.4 unless:
- a. The remaining diesel generator is currently in operation, or
- b. The remaining diesel generator has been demonstrated OPERABLE within the previous 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and
- 3. Restore the diesel generator to OPERABLE status within 14 days (See Note 1) or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
Note 1 - If the Altemate AC Diesel Generator (AACDG) is determined to be inoperable during this period, then a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> restoration period is applicable until either the AACDG or the diesel generator is returned to operable status (not to exceed 14 days from the initial diesel generator inoperability).
3/4 8-la Amendment No.
I Thornas Alexion - 2canO50303.doc Page 5 ARKANSAS - UNIT 2
Thomas Alexion - 2can050303.docPa l
3/4.8 ELECTRICAL POWER SYSTEMS BASES Containment electrical penetrations and penetration conductors are protected by either de-energizing circuits not required during reactor operation or by demonstrating the OPERABILITY of primary and backup overcurrent protection circuit breakers during periodic surveillance. The 480 volt air frame protective devices utilize electro-mechanical overcurrent elements which are mounted on the protective device and, in some instances, protective relays to trip the protective device. Actuation of the overcurrent element or relay will trip the protective device. The molded case protective devices utilize magnetic or thermal-magnetic overcurrent elements which are contained in the protective device. Actuation of each overcurrent element will trip the protective device.
TS 3.8.1.1 Action a includes an allowance for extending the allowable outage time for Startup Transformer No. 2 only, for up to 30 days. The 30-day allowance is permitted not more than once in any 10-year period, which Is considered sufficient for proper maintenance of the transformer. The 30-day window should permit extensive preplanned preventative maintenance without placing either unit In an action statement of short duration and would allow both units to.
be operating during such maintenance. Because this allowance assumes parts are prestaged appropriate personnel are available, and proper contingencies have been established, it Is not intended to be used for an unexpected loss of the transformer. Pre-established contingencies will consider the projected stability of the offsite electrical grid, the atmospheric stability projected for the maintenance window, the ability to adequately control other ongoing plant maintenance activities that coincide with the window, projected flood levels, and the availability of all other power sources. Since a station blackout is the most affected event that could occur when power sources are inoperable, the steam driven emergency feedwater pump will also be maintained available during the evolution.
TS 3.8.1.1 Action b' allows for the extension of the EDG AOT uD to 14 days. Tvoicallv.
the extended AOT will be used for voluntary Mlanned maintenance or inspections. but it may be used for corrective maintenance activities. The following continoencies shall be met pdrior to enterina the extended EDG AOT when ore-planned maintenance activities are scheduled or within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if unplanned entry into the action is required:
1 Weather conditions will be evaluated Prior to enterinq the extended EDG AOT for voluntary olanned maintenance. An extended EDG AOT will not be entered for voluntary planned maintenance purposes if official weather forecasts are predicting severe conditions (tornado or thunderstorm waminos).
a The condition of the offsne power supplv and switchvard will be evaluated.
S No discretionary switchvard maintenance will be allowed. In addition. no discretionary maintenance will be allowed on the main. auxiliary, or startuo transformers associated with the unit.
- 4. No maintenance or testing that affects the reliabiliv of the ANO-2 train associated with the OPERABLE EDG will be scheduled during the extended AOT. If any testing and maintenance activiies must be performed while the extended AOT Is in effect, the a 10CFR5065 (a)l4) evaluation will be performed.
5 The Alternate AC Diesel Generator AACDG) will be available as a backup to the Inoperable EDG and will not be used for non-safety functions such as oower peaking to the grid. After entering the extended AOT. the AACDG will be verified available every B 34 8-2 Amendment No. 48i 408,204,246, 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and treated as protected euipment.
ARICANSAS - UNIT 2
I-Thomas Alexion 3.doc Paae 1
§.
ANO-1 oersonnel will be notified to ensure no elective maintenance activities will be scheduled on the ANO-1 EDGs.
7 The steam driven emergency feedwater Dump will not be taken out of service for planned maintenance activities and will be treated as protected equipment.
Note 1 of TS 3.8.1.1 Action b' requires operability of the AACDG when an EDG Is removed from service. If the AACDG becomes inoperable, then the allowable outaae time Is reduced to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> not to exceed 14 days from the initial entry related to the inoperable EDG.
Either the AACDG or the EDG mav be restored within the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If the EDG is restored.
then TS 3.8.1.1. action "b" is exited. If the AACDG is restored within the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. then restoration of the EDG must be accomplished within the initial 14 day AOT (i.e. 14 days from the time the EDG was initially declared inoperable and action b was entered).
TS 3.8.1.1 Action c.4" is entered when one of the inoperable A.C. Sources is restored to an OPERABLE status as required by Action uc.3" and requires restoration of the remaining inoperable A.C. Source to an OPERABLE status. The allowable restoration time in Action c.4" for the remaining inoperable A.C. source began when the component initially became Inoperable.
not restored within the AOT, then a plant shutdown is required. The requirement associated with the AACDG (reference Action b.3" Note 1) is applicable to the EDG AOT.
TS 3.8.1.1 Action 8e.3' requires restoration of the remaining inoperable EDG to an OPERABLE status. The time allowed for restoration is based on the time at which the remaining inoperable EDG was initially declared inoperable. If not restored within the AOT, then a plant shutdown is required. The requirement associated with the AACDG (reference Action ab.3,0 Note 1) is applicable to the EDG AOT TS 4.8.1.2.c.3 demonstrates the EDG load response characteristics and capability to reject the largest single load without exceeding predetermined voltage and frequency while rnaintaining a specified margin to the overspeed trip. For ANO-2, the single load for each EDG is the Service Water pump, rated at 800 HP (636.9 KW).
TS 3.8.2.3 Action "b" requires the performance of SR 4.8.2.3.a.1 within one hour and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter for a loss of one of the required full capacity chargers. If any Category A limit In Table 4.8-2 is not met while a charger is inoperable, the associated battery bank shall be declared inoperable and ACTION "e entered. The Category A limits in Table 4.8-2 specify the nomal limits for electrolyte level, float voltage and specific gravity for each designated pilot cell. When TS 3.8.2.3 ACTION "b is entered without the associated battery bank being on float (i.e. charger not connected to the bus), pilot cell float voltage is determined by measuring pilot cell voltage. The term "full capacity charger' as used in TS 3.8.2.3 Is defined as a charger that is capable of supplying an output of 2 300 amperes.
83/4 8-2a Amendment No. 446, 48, 204, 24, I Thornas Alexion - 2canO50303.doc Paoe 1 X ARKANSAS - UNIT 2
I Thomas Alexion - 2cari050303.doc Paae IE To 2CAN050303 Ust of Regulatory Commitments I Thomas Alexion - 2canO50303.doc Paae I1£
I Thomas Alexion - 2can050303.doc Paae 1
List of Regulatory Commitments The following table identifies those actions committed to by Entergy related to this request Any other statements in this submittal are provided for nformation purposes and are not considered to be regulatory comitments.
TYPE (Check one)
SCHEDULED COMPLETION COMMITMENT DATE (f Required)
ONE-CONTINUING TIME COMPLIANCE ACTION
- 1. Weather conditions will be evaluated prior to x
entering the extended EDG AOT for voluntary planned maintenance. An extended EDG AOT will not be entered for voluntary planned maintenance purposes if official weather forecasts are predicting severe conditions (tomado or thunderstorm wamings).
- 2. The condition of the offsite power supply and x
switchyard will be evaluated prior to entering the extended AOT.
- 3. No discretionary switchyard maintenance will be x
allowed. In addition, no discretionary maintenance will be allowed on the main, auxiliary, or startup transformers associated with the unit.-
- 4. No maintenance or testing that affects the x
reliability of the ANO-2 train associated with the OPERABLE EDG will be scheduled during the extended AOT. If any testing and maintenance activities must be performed while the extended AOT is in effect, a 10CFR50.65 (a)(4) evaluation will be performed.
- 5. The Altemate A.C. Diesel Generator (AACDG) will x
be available as a backup to the inoperable EDG and will not be used for non-safety functions such as power peaking to the grd. After enterng the extended AOT, the AACDG will be verified available every 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and treated as protected equipment.
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I Thomas Alexion - 2can050303.doc Page 2( to 2CAN050303 Page 20 of 3 List of Regulatory Commitments Continued TYPE (Check one)
SCHEDULED COMPLETION COMMITMENT DATE (if Required)
ONE-CONTINUING TIME COMPUANCE ACTION
- 6. ANO-1 personnel will be notified to ensure no x
elective maintenance activities will be scheduled on the ANO-1 EDGs and will be made aware of the dedication of the AACDG to ANO-2.
- 7. The steam driven emergency feedwater pump will x
not be taken out of service for planned maintenance activities and will be treated as protected equipment.
S. The system dispatcher will be contacted once per x
day and informed of the EDG status along with the power needs of the facility.
- 9. Should a tornado or thunderstorm warning be x
issued for the local area, an operator will be available should local operation of the AACDG be required as a result of on-site weather-related damage.
- 10. ANO-2 on-shift Operations crews will discuss and x
review appropriate normal and emergency operating procedures upon or prior to assuming the watch for the first time after having scheduled days off while the AOT is in effect.
- 11. ANO-2 Operations crews will be briefed x
conceming the ANO-2 EDG activities, including compensatory measures established and the importance of promptly starting and aligning the AACDG following instruction of the ANO-2 Shift Manager upon the loss of power event. This briefing will be performed upon or prior to assuming the watch for the first time after having scheduled days off while the AOT Is in effect I Thomnas Alexion - 2canO50303.doc Paoe 2(
ThomasAlexion - 2canO50303.doc P
_.age 21 to 2CAN050303 Page 21 of 3
- 12. During the EDG outage, ANO commits to control During EDG welding and transient combustibles and to Outage establish continuous fire watches in the vicinity of 2Alr2A22A9.
I ThmsAlxo
-2a0033dc ae2 to 2CAN050303 Page 22 of 3 Ust of Regulatory Commitments Continued TYPE (Check one)
SCHEDULED COMPLETION COMMITMENT DATE (if Required)
ONE-CONTINUING TIME COMPUANCE ACTION
- 13. During the EDG outage, ANO commits to During EDG control welding and transient combustibles in Outage the following areas: the transformer yard; the south switchgear room (SS/2100-Z); the cable spreading room (GI 2098-L); Intake structure (00 / IS); diesel corridor (JJ/21 09-U), and lower south electricaVpiping penetration room (EE/2055SC), and Electrical Equipment Room (TT/2108-S).
- 14. Prior to the EDG outage ANO commits to Prior to EDG provide In a crew brief to ANO-2 Operations Outage personnel and ANO-1 fire brigade personnel refresher information related to fighting electrical fires and fires that may occur In the transformer yard. The crew brief will include relevant industry operating experience related to fires In these areas and will also include a discussion of equipment restoration.
- 15. Prior to an EDG outage the operability of the fire Prior to the suppression in the transformer yard will be EDG Outage confirmed. This will be accomplished by verifying the surveillances are current and the system Is not isolated. If the system is isotated, then fire hoses will be staged to the transformer yard area during the EDG maintenance outage.
I Thomas Alexion - 2canO50303.doc Pace 2 I
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