ML102160562

Notice of Enforcement Discretion Request, Technical Specification 3.8.1, AC Sources - Operating, TS 3.78, Nuclear Service Water System, TS 3.7.5, Auxiliary Feedwater System, TS 3.6.6, Containment Spray System.

ML102160562
Person / Time
Site:	Catawba
Issue date:	08/02/2010
From:	Morris J Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML102160562 (14)

Text

Ener JEDuke R.MORRIS Vice President Duke Energy Corporation Catawba Nuclear Station 4800 Concord Road York, SC 29745 803-701-4251 803-701-3221 fax August 2, 2010 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555

Subject:

Duke Energy Carolinas, LLC (Duke Energy)

Catawba Nuclear Station, Unit 1 Docket Number 50-413 Notice of Enforcement Discretion (NOED) Request Technical Specification (TS) 3.8.1, "AC Sources - Operating" (primary TS)

TS 3.7.8, "Nuclear Service Water System (NSWS)" (secondary TS)

TS 3.7.5, "Auxiliary Feedwater (AFW) System" (secondary TS)

TS 3.6.6, "Containment Spray System" (secondary TS)

Enclosed is the written documentation of the background and technical information supporting the Catawba Nuclear Station Unit 1 NOED request. This information was discussed with the NRC in a telephone conference call on July 29, 2010. The NOED was subsequently verbally granted by the NRC following the conference call. This submittal fulfills the requirement to submit the written NOED request within two working days of the NRC granting the request.

This request concerns an extension of the TS Completion Time for Diesel Generator (DG) 1A inoperability from the current 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> by an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, for a total of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. The requested extension is necessary to restore the DG to operable status. The details of this request are fully explained in the enclosure to this letter.

Catawba had been engaged in the removal and reinstallation of the one of the DG turbochargers due to foreign material entry. The foreign material is a piece of one of the engine-mounted thermocouples which had broken and had been transported to the turbocharger. As shown in the enclosed justification, Duke Energy maintains that granting of discretionary enforcement in this case is in the best interest of nuclear safety.

This NOED request was reviewed and approved by the Catawba Plant Operations Review Committee (PORC) on July 29, 2010.

This NOED request was approved by the NRC on July 29, 2010. Catawba restored DG IA and all affected supported equipment with a 72-hour TS Completion Time to operable status by 0308 hours0.00356 days <br />0.0856 hours <br />5.092593e-4 weeks <br />1.17194e-4 months <br /> on July 30, 2010. This was prior to the time that Unit 1 would have had to be placed in Mode 3 (0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on July 30, 2010, or six hours after the expiration of the applicable TS Completion Time for DG 1A at 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> on July 30, 2010).

www. duke-energy com

U.S. Nuclear Regulatory Commission Page 2 August 2, 2010 Should you have any questions concerning this information, please contact L.J. Rudy at (803) 701-3084.

Very truly yours, James R. Morris LJR/s Enclosure

U.S. Nuclear Regulatory Commission Page 3 August 2, 2010 xc (with enclosure):

L.A. Reyes U.S. Nuclear Regulatory Commission Regional Administrator, Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 G.A. Hutto, III Senior Resident Inspector U.S. Nuclear Regulatory Commission Catawba Nuclear Station J.H. Thompson (addressee only)

NRC Project Manager U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 08 G9A Rockville, MD. 20852-2738 S.E. Jenkins Manager Radioactive & Infectious Waste Management Division of Waste Management South Carolina Department of Health and Environmental Control 2600 Bull St.

Columbia, SC 29201

Enclosure Catawba Nuclear Station, Unit I Request for Enforcement Discretion TS 3.8.1, "AC Sources - Operating" TS 3.7.8, "Nuclear Service Water System (NSWS)"

TS 3.7.5, "Auxiliary Feedwater (AFW) System" TS 3.6.6, "Containment Spray System"

Background

The onsite standby power source for each 4160 volt Engineered Safety Features (ESF) bus at Catawba is a dedicated Diesel Generator (DG). For each unit, DGs A and B are dedicated to ESF buses ETA and ETB, respectively. A DG starts automatically on a Safety Injection (SI) signal (i.e., low pressurizer pressure or high containment pressure) or on an ESF bus degraded voltage or undervoltage signal. After the DG has started, it will automatically tie to its respective bus after offsite power is tripped as a consequence of ESF bus undervoltage or degraded voltage, independent of or coincident with an SI signal. With no SI signal, there is a ten-minute delay between the degraded voltage signal and the DG start signal. The DGs will also start and operate in the standby mode without tying to the ESF bus on an SI signal alone. Following the trip of offsite power, a sequencer strips loads from the ESF bus. When the DG is tied to the ESF bus, loads are then sequentially connected to its respective ESF bus by the automatic load sequencer. The sequencing logic controls the permissive and starting signals to motor breakers to prevent overloading the DG by automatic load application.

In the event of a loss of preferred power, the ESF electrical loads are automatically connected to the DGs in sufficient time to provide for safe reactor shutdown and to mitigate the consequences of a Design Basis Accident (DBA) such as a Loss of Coolant Accident (LOCA).

Certain required unit loads are returned to service in a predetermined sequence in order to prevent overloading the DG in the process. Approximately one minute after the initiating signal is received, all loads needed to recover the unit or to maintain it in a safe condition are returned to service.

TS 3.8.1 governs the DGs. Limiting Condition for Operation (LCO) 3.8.1 requires two operable DGs for each unit that is in Modes 1, 2, 3, and 4. With one DG inoperable, the inoperable DG must be restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> per Required Action B.4. If this is not accomplished, the unit must be placed in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> per Required Actions G.1 and G.2.

The NSWS provides a heat sink for the removal of process and operating heat from safety related components during a DBA or transient. During normal operation, and a normal shutdown, the NSWS also provides this function for various safety related and non-safety related components.

The NSWS consists of two independent loops (A and B) of essential equipment, each of which is shared between the two Catawba units. Each loop contains two NSWS pumps, each of which is supplied from a separate DG. Each set of two pumps supplies two trains (1A and 2A, or 1 B and 2B) of essential equipment through common discharge piping. While the pumps are unit designated (i.e., 1A, 1B, 2A, 2B), all train-related pumps receive automatic start signals 1

from a corresponding train-related SI or blackout signal from either unit. Therefore, a pump designated to one unit will supply post-accident cooling to equipment in that loop on both units.

For example, the 1A NSWS pump, whose emergency power is supplied by DG 1A, will supply post-accident cooling to NSWS trains 1A and 2A.

One NSWS loop containing two operable NSWS pumps has sufficient capacity to supply post-LOCA loads on one unit and shutdown and cooldown loads on the other unit. Thus, the operability of two NSWS loops assures that no single failure will keep the system from performing the required safety function. Additionally, one NSWS loop containing one operable NSWS pump has sufficient capacity to maintain one unit indefinitely in Mode 5 (commencing 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> following a trip from full power) while supplying the post-LOCA loads of the other unit.

Thus, after a unit has been placed in Mode 5, only one NSWS pump and its associated DG are required to be operable on each loop, in order for the system to be capable of performing its required safety function, including single failure considerations.

TS 3.7.8 governs the NSWS. LCO 3.7.8 requires two operable NSWS trains for each unit that is in Modes 1, 2, 3, and 4. With one NSWS train inoperable, the inoperable NSWS train must be restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> per Required Action A.1. If this is not accomplished, the unit must be placed in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> per Required Actions C.1 and C.2.

The NSWS also supports the AFW and Containment Spray Systems since it serves as the assured water source for these systems. TS 3.7.5 governs the AFW System. LCO 3.7.5 requires three AFW trains to be operable in Modes 1, 2, and 3, and in Mode 4 when the steam generators are relied upon for heat removal. With one AFW train inoperable in Mode 1, 2, or 3 for reasons other than an inoperable steam supply to the turbine-driven AFW pump, the inoperable AFW train must be restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> per Required Action B.1. If this is not accomplished, the unit must be placed in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Mode 4 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> per Required Actions C.1 and C.2. TS 3.6.6 governs the Containment Spray System. LCO 3.6.6 requires two containment spray trains to be operable in Modes 1, 2, 3, and

4. With one containment spray train inoperable, the inoperable containment spray train must be restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> per Required Action A.1. If this is not accomplished, the unit must be placed in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Mode 5 within 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> per Required Actions B.1 and B.2.

Need for NOED Duke Energy is requesting that the NRC exercise discretion to not require compliance with TS 3.8.1, Required Action B.4 for the inoperable DG, TS 3.7.8, Required Action A.1 for the inoperable NSWS train, TS 3.7.5, Required Action B.1 for the inoperable AFW train, and TS 3.6.6, Required Action A.1 for the inoperable containment spray train. Catawba is specifically requesting that the Completion Times of these Required Actions be extended from the current 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> by an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, for a total of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. The requested extension of these Completion Times will allow work to be completed to restore DG IA to operable status.

Basis for NOED Duke Energy has reviewed NRC Regulatory Issue Summary 2005-01, "Changes to Notice of Enforcement Discretion (NOED) Process and Staff Guidance", and the accompanying NRC 2

Inspection Manual Part 9900 Technical Guidance, "Operations - Notices of Enforcement Discretion", and has concluded that Part 9900 Section B.2.1, "Situations Affecting Radiological Safety - Regular NOEDs", Criterion 1.a is satisfied. This criterion applies to plants in power operation desiring to avoid unnecessary transients as a result of compliance with the license condition and, thus, minimize the potential safety consequences and operational risks. The basis for this conclusion and other information required to support a request for NOED is provided below.

1. The Technical Specification or other license condition that will be violated:

Duke Energy Response:

Catawba is requesting enforcement discretion from TS 3.8.1, Required Action B.4, TS 3.7.8, Required Action A.1, TS 3.7.5, Required Action B.1, and TS 3.6.6, Required Action A. 1, as indicated above. TS 3.8.1 is the primary TS due to the inoperability of DG 1A. TS 3.7.8 is affected because DG 1A is required to be operable for NSWS Train 1A to be considered operable. TS 3.7.5 and TS 3.6.6 are affected due to the fact that when a shared NSWS component is inoperable, both units initially enter the Condition for one inoperable NSWS train. It is subsequently permissible for the operators to isolate one NSWS train's flowpath to the corresponding train of the AFW System and the Containment Spray System. The purpose of this isolation is to allow one of the units to exit the Condition for one inoperable NSWS train; however, the isolated AFW and containment spray trains must be considered inoperable and their Conditions must be entered.

2. The circumstances surrounding the situation: including likely causes; the need for prompt action; action taken in an attempt to avoid the need for a NOED; and identification of any relevant historical events.

Duke Energy Response:

In January 2010, it was observed that the exhaust cylinder temperature for the number 6 cylinder on the right bank (6R) of DG 1A was reading approximately 300 degrees F low.

Administrative processes were initiated to investigate and resolve. Also, a review of the respective temperature data for the other 15 cylinders that had not exhibited changes showed this to be only an indication problem. On May 19, 2010, Problem Investigation Process (PIP) C-10-02963 was generated for Catawba. The purpose of this PIP was to ensure that the work request/order that had been previously initiated was performed in a timely manner to allow accurate trending of DG data, which is used to support engine reliability and operability.

DG cylinder exhaust temperature data is used as one input to help determine the functionality of the fuel injection system. Although the identified problem was determined to be an indication only concern, it was deemed prudent to resolve the problem.

The PIP noted that the respective work order needed to be scheduled sooner than the originally planned DG work day scheduled for the Fall of 2010. In response to this PIP, 3

work order 01920283 was scheduled for the next planned DG work day on July 27, 2010.

DG 1A was removed from service and declared inoperable at 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> on July 27, 2010 in support of the planned DG work day's activities. While performing work to replace the DG 1A number 6R cylinder exhaust thermocouple per work order 01920283, the end of the thermocouple was found to be broken off. The total probe length is approximately 4" and approximately 3/8" in diameter. The Operations Shift Manager was notified of the as-found condition and PIP C-10-04459 was generated.

Attempts to locate the thermocouple probe with a boroscope were not successful. Plant management convened a Unit Threat Team and plans were developed to remove the turbocharger to support locating the thermocouple probe. The broken piece was subsequently found in one piece (i.e., it had not broken into smaller pieces) in the stationary vane of the right bank turbocharger. There was no damage to the turbocharger.

To determine the cause of the thermocouple failure, the failed thermocouple and two other non-failed thermocouples from DG 1A were sent to Duke Energy's metallurgical laboratory for analysis. The analysis showed that the cause of the thermocouple failure was mechanical fatigue due to high-cycle, low-amplitude, cyclic stresses typical of vibration. Refer to Item 4.e below for additional details concerning the failure mechanism. The other two thermocouples showed no signs of degradation.

Catawba took action in an attempt to avoid the need for this NOED request. This included initiating a Unit Threat Team, and performing the repair under a complex maintenance plan utilizing 24-hour coverage.

There have been no other relevant historical events at Catawba in conjunction with this issue.

3. Information to show that the cause and proposed path to resolve the situation are understood by the licensee, such that there is a high likelihood that planned actions to resolve the situation can be completed within the proposed NOED time frame.

Duke Enervgy Response:

The failed thermocouple piece was located in the stationary vane of the right bank turbocharger. The failed piece had not broken up into smaller pieces while traversing through the exhaust manifold prior to entering the turbocharger. No damage was observed to the turbocharger or to other engine components from the thermocouple piece. Therefore, this NOED request is limited to the time to complete maintenance on the DG, to conduct required DG testing, and to perform required system realignments.

It is anticipated that the remainder of the maintenance, subsequent testing, and system realignments will require less than 12 additional hours beyond the expiration of the applicable TS Completion Times.

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4. The safety basis for the request, including an evaluation of the safety significance and potential consequences of the proposed course of action.

a. Provide the incremental conditional core damage probability (ICCDP) and incremental conditional large early release probability (ICLERP) associated with the period of enforcement discretion.

Duke Enerav Response:

Using the Catawba Probabilistic Risk Assessment (PRA) model, unavailability of DG 1A and isolation of NSWS to AFW and containment spray trains as the assured source results in an Incremental Conditional Core Damage Frequency of 7.55 E-08/day and an Incremental Conditional Large Early Release Frequency of 5.52 E-09/day. These values would justify an additional 6.62 days of operation to restore the DG to service.

The ICCDP and ICLERP have been evaluated to be:

24-hour extension Total'time of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> ICCDP 7.55 E-08 3.02 E-07 ICLERP 5.52 E-09 2.208 E-08 The above values are less than Duke Energy procedural acceptance criteria of 5 E-07 and 5 E-08, respectively for a total outage period of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. (This includes the 72-hour existing TS Completion Times.)

b. Discuss the dominant risk contributor (cutsets/sequences) and summarize the risk insights for the plant-specific configuration the plant intends to operate in during the period of enforcement discretion.

Duke Energy Response:

In the ICCDP results, the dominant sequences are initiated by Loss of Offsite Power (LOOP) and tornadoes. The LOOP sequences involve failure to recover offsite power and failure of the redundant DG 1 B to start. The tornado sequences also involve failure of DG 1 B to start in addition to the AFW turbine-driven pump failing to run. The ICLERP results are dominated by similar type sequences.

c. Explain compensatory measures that will be taken to reduce the risk associated with the specified condition.

Duke Energy Response:

In general terms, the following compensatory measure strategy will be employed:

1. Defer non-essential surveillances or other maintenance activities in the switchyard where human error could contribute to the likelihood of a LOOP.

This has not been included in the quantitative evaluation.

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2. Defer non-essential surveillances or other maintenance activities on risk-significant equipment. This equipment includes DG 1 B, the AFW turbine-driven pump, and the Standby Shutdown System (SSS).

The following specific compensatory measures are being taken to reduce the risk during the NOED period:

• During the period of enforcement discretion, no elective maintenance or testing will be planned on DG 1 B or on NSWS train 1B. In addition, for Unit 1, during this period, no elective maintenance or testing will be planned on the operable equipment that relies upon NSWS Train 1 B as a support system.

" During the period of enforcement discretion, no elective maintenance or testing will be planned on AFW Train 1A, Train 1 B, or the Unit 1 turbine-driven AFW pump.

• During the period of enforcement discretion, no elective maintenance or testing will be planned on Unit 1 Component Cooling Water (CCW) System.

• During the period of enforcement discretion, no elective maintenance or testing will be planned on Chemical Volume and Control System Train 1A or Train 1B.

• During the period of enforcement discretion, no elective maintenance or testing will be planned on the SSS.

• During the period of enforcement discretion, no elective maintenance or testing will be planned on the portions of the drinking water system that are relied upon to provide backup cooling to the Train 1A centrifugal charging pump.

• During the period of enforcement discretion, no elective maintenance or testing will be planned on the Train 1A or Train 1 B essential AC power switchgear including the 4160 volt busses, load centers, and motor control centers.

" During the period of enforcement discretion, no elective maintenance or testing will be planned on switchyard components or the transformers that feed the Train 1A and Train 1B 4160 volt busses.

• Station personnel will communicate with the System Operations Center once each shift regarding the unit status and the need to maintain grid stability during the period of enforcement discretion.

• In accordance with System Operations Management Procedure 02-02, "Operations Roles In The Risk Management Process", selected plant equipment will be posted as "protected" to ensure that no persons inadvertently enter the area of the equipment. This equipment includes, but is not limited to, the switchyard and main transformer yards, the essential switchgear rooms, the SSS, and selected pumps.

• Prior to entering the period of enforcement discretion, the operating crews will review the procedures regarding starting the SSS and establishing backup cooling to the Train 1A charging pump.

• Catawba has installed permanent flood protection barriers in the turbine building to mitigate turbine building flooding. In addition, to help reduce any potential flooding issues, no elective maintenance or testing will be planned on the Condenser Circulating Water System.

• To mitigate the risk of a potential core damage event, an operator action has been identified. This involves dispatching operators to throttle key AFW valves that supply flow to the steam generators prior to the depletion of the vital batteries, thereby preventing steam generator overfill and thus protecting the 6

steam supplies to the AFW turbine-driven pump. Catawba will dedicate an operator on each shift with this responsibility. This action has been previously proceduralized and validated.

• Any yard digging activities over active NSWS piping will be prohibited during the period of enforcement discretion.

• Station personnel will verify once per shift that the above compensatory measures remain in place during the period of enforcement discretion.

• The Unit Threat Team will remain in place throughout the evolution.

d. Discuss how compensatory measures are accounted for in the PRA. These modeled compensatory measures should be correlated, as applicable, to the dominant PRA sequences identified in Item 4.b above. In addition, other measures not directly related to the equipment out-of-service may also be implemented to reduce overall plant risk and, as such, should be explained.

Compensatory measures that cannot be modeled in the PRA should be assessed qualitatively.

Duke Energy Response:

The risk assessment has taken into account that risk-significant systems are assumed to be available. Deferring surveillances or other maintenance activities in the switchyard is not modeled in the PRA. However, since this is aligned with the dominant risk contributors, namely the LOOP sequence, it should result in a significant risk reduction during the NOED period. Although not all of the above compensatory measures are modeled in the PRA, they collectively serve to mitigate the risk associated with the granting of the NOED.

e. Discuss the extent of condition of the failed or unavailable component(s) to other trains/divisions of equipment and what adjustments, if any, to the PRA common cause factors have been made to account for potential increases in the failure probabilities. The method to use to determine the extent of condition should be discussed. It is recognized that a formal root cause or apparent cause is not required given the limited time available in determining acceptability of a proposed NOED. However, a discussion of the likely cause should be provided with an associated discussion of the potential for common cause failure.

Duke Energy Response:

The method used to evaluate extent of condition was review of the metallurgical analysis of the failed thermocouple, both nuclear and non-nuclear industry operating experience, operating performance of the DG 1A engine following the failure of the exhaust thermocouple, and the actual as-found condition and location of the failed thermocouple. There are currently no open work orders on any of the exhaust thermocouples on the 1 B, 2A, and 2B DG engines. Review of operating data also shows that the respective thermocouples are correctly indicating engine cylinder exhaust temperatures, thus proving there are currently no failed thermocouples on the 1 B, 2A, and 2B DG engines. This data shows that there is not an immediate operability concern with operating the DGs with the Alnor type 1118J (special) 7

thermocouples installed in the cylinder exhaust piping. Industry operating experience supports this being a unique failure and not a precursor to future failures.

Although the failure was due to mechanical fatigue, there are certain inputs into the incubation period required to develop an initiating crack that may vary for individual thermocouples. Although the information supports this as being a unique failure, there is no way to conclude that another failure will not occur. Based on the most probable location of the crack to occur, the design of the turbocharger, and the actual as-found condition of the failed piece, Engineering concluded that it is unlikely that a future thermocouple failure would actually damage a turbocharger and fail a DG engine. Engineering concluded that there are no extent of condition concerns with the 1B, 2A, and 2B DG engines.

It should also be noted that there is approximately six months of operating history on DG 1A with the faulted thermocouple and that this did not cause any problems with the DG.

Finally, there was no need to make any adjustments to any PRA common cause factors as a result of this event.

f. Discuss external event risk for the specified plant configuration. An example of external event risk is a situation where a reactor core isolation cooling pump (RCIC) has failed and a review of the licensee's individual plant examination of external events or full-scope PRA model identifies that the RCIC pump is used to mitigate certain fire scenarios. Action may be taken to reduce fire ignition frequency in the affected areas or reduce human error associated with time critical operator actions in respond to such scenarios.

Duke Energy Response:

External events are accounted for in the PRA model with the exception of the seismic events. The seismic results typically are not sensitive to unavailabilities of individual components and the seismic contribution is judged to be insignificant relative to the non-seismic results.

g. Discuss forecasted weather conditions for the NOED period and any plant vulnerabilities related to weather conditions.

Duke Energy Response:

Based upon the forecast and the current status of the plant equipment, there are no vulnerabilities expected due to weather conditions for the NOED period. Forecast details are included below:

Although the weather forecast predicts the potential for thunderstorms, severe weather such as a tornado is not likely for the Catawba site region over the period during which the enforcement discretion is in effect.

Thursday night: Isolated thunderstorms this evening. Skies will become partly cloudy after midnight. Low 74F. Winds NNW at 5 to 10 mph. Chance of rain 30%.

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Friday: Except for a few afternoon clouds, mainly sunny. Hot. High near 95F.

Winds NNE at 5 to 10 mph.

Friday night: A few clouds. Low 72F., Winds NE at 5 to 10 mph.

Saturday: Scattered thunderstorms possible. Highs in the low 90s and lows in the low 70s.

Sunday: Scattered thunderstorms possible. Highs in the upper 80s and lows in the low 70s.

5. The justification for the duration of the noncompliance.

Duke Enerav Response:

The duration of the non-compliance is limited to the time required to complete the maintenance on DG 1A, to conduct the required DG testing, and to perform the required system realignments. Catawba is therefore requesting that the current 72-hour Completion Times associated with the above TS be extended by 24 additional hours, for a total of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />.

6. The condition and operational status of the plant (include safety-related equipment out of service or otherwise inoperable).

Duke Energy Response:

Unit 1 is currently in Mode 1 at 100% power. Duke Energy has reviewed the plant TS, the plant operating schedule, and the Work Management System. This review determined that no TS or risk-significant equipment that has an impact on the above PRA results is inoperable or planned to be taken out of service while the NOED is in effect.

7. The status and potential challenges to off-site and on-site power sources.

Duke Energy Response:

There are no activities scheduled in the switchyard or on the plant transformers that will adversely affect risk during the requested enforcement discretion period. Additionally, no activities are scheduled for the opposite train DG or the opposite train of the NSWS, AFW System, or Containment Spray System.

8. The basis for the licensee's conclusion that the noncompliance will not be of potential detriment to the health and safety of the public.

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A Duke Energy Response:

There is minimal safety consequence associated with this request. Granting of enforcement discretion will not have any adverse safety impact. DG 1 B, NSWS train 1 B, AFW train 1 B, and containment spray train 1B are all fully operable and capable of performing their required safety functions in the unlikely event of a DBA or other event occurring while enforcement discretion is in effect. This request has no significance from the standpoint of operator or public dose in the event of an accident. All dose analysis results will continue to be met.

9. The basis for the licensee's conclusion that the noncompliance will not involve adverse consequences to the environment.

Duke Enerciv Response:

This request for enforcement discretion will not result in any significant changes in the types, or significant increase in the amounts, of any effluents that may be released offsite, In addition, no significant increase in individual or cumulative occupational radiation exposures will be involved as a result of the request. Therefore, it can be concluded that the NRC's granting of this request for enforcement discretion will not involve any adverse consequences to the environment.

10. A statement that the request has been approved by the facility organization that normally reviews safety issues (Plant On-site Review Committee, or its equivalent).

Duke Energy Response:

This NOED request was reviewed and approved by the Catawba Plant Operations Review Committee (PORC) on July 29, 2010.

11. The request must specifically address which of the NOED criteria for an appropriate condition specified in Section B is satisfied and how it is satisfied.

Duke Eneray Response:

Duke Energy is submitting this NOED request in accordance with NRC Inspection Manual Part 9900 Technical Guidance, "Operations - Notices of Enforcement Discretion", and is requesting discretion based on Section B.2.1, "Situations Affecting Radiological Safety - Regular NOEDs", Criterionl.a. This criterion applies to plants in power operation desiring to avoid unnecessary transients as a result of compliance with the license condition and, thus, minimize the potential safety consequences and operational risks. The safety consequences and operational risks for Catawba were reviewed as a part of this NOED request and are documented within this submittal.

12. Unless otherwise agreed as discussed in Section B, a commitment is required from the licensee that the written NOED request will be submitted within two working days and the follow-up amendment will be submitted within four working days of verbally granting the NOED. The licensee's amendment request must 10

describe and justify the exigent circumstances (see 10 CFR 50.91(a)(6)). The licensee should state if staff has agreed during the teleconference that a follow-up amendment is not needed. If the licensee intends to propose a temporary amendment, the licensee's amendment request shall include justification for the temporary nature of the requested amendment.

Duke Energy Response:

Upon discussion with the NRC on July 29, 2010, Duke Energy will submit a written NOED request within two working days.

A follow-up license amendment for a permanent change to the Completion Times for the affected TS is not necessary.

13. In addition to Items 1-12 above, for severe-weather NOED requests the licensee must provide additional specified information.

Duke Energy Response:

This is not a severe-weather NOED request. Weather considerations are discussed in Item 4.

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