TMI-14-102, Request for Enforcement Discretion for Technical Specification (TS) 3.3.2, Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems

Request for Enforcement Discretion for Technical Specification (TS) 3.3.2, Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems

ML14197A293
Person / Time
Site:	Three Mile Island
Issue date:	07/15/2014
From:	Newcomer M Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TMI-14-102
Download: ML14197A293 (19)

Text

Exelon Generation TMI-14-102 July 15, 2014 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 USNRC Docket No. 50-289

Subject:

Request for Enforcement Discretion for Technical Specification (TS) 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" On July 13, 2014, Exelon Generation Company, LLC (EGC) verbally requested a Notice of Enforcement Discretion (NOED) associated with Technical Specification (TS) 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" for Three Mile Island Nuclear Station (TMI), Unit 1. The following information was discussed with representatives of the U.S. Nuclear Regulatory Commission (USNRC) on July 13, 2014 at 15:00 hours, with subsequent approval being verbally granted by the USNRC at 17:19 hours.

On July 10, 2014 a small leak (1 drop every 2 minutes) was identified from a welded connection upstream on the high pressure injection (HPI) line side of an instrument root isolation valve MU-V-1034. There is a short length (less than 2 inches) of schedule 160, /2 inch diameter, type 304 stainless steel (SST) pipe that connects to MU-V-1 034 SST valve body (Enclosure 2). This is an ASME Class 2 line. Valve MU-V-1 034 is the high side root isolation valve for the 'B' HPI line flow instrument, MU-FT-1 127, sensing differential pressure (dP) across flow element, MU FE-2. The leak location is outside containment inside the Auxiliary Building. See Enclosure 3 for a picture of the leak. During normal power operation the subject line has no flow but is pressurized to makeup/HPI pump discharge pressure up to 3050 psig. The function of the instrument line is to measure the flowrate of high pressure injection provided in the 'B' HPI line.

Isolation of this leak causes the 'A' train of HPI to be inoperable, resulting in entry of a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Limiting Condition for Operation (LCO) under TMI, Unit 1 Technical Specification 3.3.2.

TMI, Unit 1 TS 3.3.2 allows one train of HPI to be removed from service for maintenance during reactor operation for not more than 72 consecutive hours. The small leak was identified by an operator during a plant walk-through at approximately 17:30 on July 10, 2014. This started the 72-hour LCO time clock. Characterization of the leak commenced which included additional visual examinations and personnel resources to support technical evaluation and planning activities. The station response center (Outage Control Center - OCC) was activated and has been continuously staffed. The area of the leak was non-destructively examined (NDE) in parallel with development of a repair plan. NDE (dye penetrant testing) identified three indications on the weld at the valve. Based upon initial NDE results (Enclosure 4), detailed work order repair activities were written and a schedule developed. The resulting schedule showed completion of the repair and return of the 'A' train of HPI to operable status to be within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO (return to service time of 17:30 on July 13, 2014). During execution of the repair activity, adequate isolation could not be obtained. Makeup/HPI fluid leaked past boundary isolation closed valves. These delays resulted in additional hours to the planned repair

July 15, 2014 U. S. Nuclear Regulatory Commission Page 2 activities. This extends the total inoperable period of time to effect necessary repairs. The weld repair will be performed by grinding out the old weld and applying a re-weld to the area to remove the flaw. The weld repair shall meet the requirements of the original code of construction, USAS B31.7 1968 draft with June 1968 Errata. The repair is well understood including the necessary acceptance criteria to return the system to operable status. The delay in achieving isolation necessitated the request for enforcement discretion.

The enclosures provide the information necessary for approval of the requested enforcement discretion. The enclosures were reviewed and approved by the Three Mile Island Nuclear Station (TMI), Unit 1, Plant Operations Review Committee (PORC) in accordance with the requirements of the EGC Quality Assurance Program. There are no regulatory commitments contained within this letter.

Should you have any questions or comments regarding this matter, please contact David Atherholt at (717) 948-8364.

Respectfully,

VOY4\Y *C~r INkdc,"'r1 Mark Newcomer Plant Manager - Three Mile Island Nuclear Station, Unit 1 Exelon Generation Company, LLC

Enclosures:

1. Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems"

2. Piping and Instrumentation Diagram

3. Picture of Leak

4. NDE Report cc: Regional Administrator - USNRC Region I USNRC Senior Resident Inspector - Three Mile Island Nuclear Station, Unit 1 USNRC Project Manager - NRR - Three Mile Island Nuclear Station, Unit 1

ENCLOSURE 1 Three Mile Island Nuclear Station, Unit 1 Docket No. 50-289 Renewed Facility Operating License No. DPR-50 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems"

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems"

1. Specifically address what type of NOED is being requested (regular or natural event), which of the NOED criteria for appropriate plant conditions specified in IMC 0410, subsection 03.03 is satisfied, and how those criteria are satisfied. (Also reference subsection 06.02 of IMC 0410).

Exelon Generation Company, LLC, (EGC) is requesting enforcement discretion for Three Mile Island Nuclear Station, Unit 1 (TMI), from Technical Specification (TS) 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" due to a pressure boundary leak in the Makeup/High Pressure Injection (HPI) system.

A regular NOED is being requested in accordance with NOED Criterion 03.03.b of NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion". Criterion 03.03.b involves the following condition: (b) an unnecessary down-power or the shutdown of a reactor without a corresponding health and safety benefit. The determination of this criterion's applicability is based on understanding that the additional time to perform the repairs beyond the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO will not result in more than a minimal increase in radiological risk in a quantitative assessment that risk will be within the normal work control levels (ICCDP less than or equal to 5E-7). The request is for an additional 46.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> extension to this LCO.

2. Provide a description of the TS or other license conditions that will be violated.

TMI, hereby requests enforcement discretion from the requirements of TS 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" which says:

"Maintenance or testing shall be allowed during reactor operation on any component(s) in the makeup and purification, decay heat, RB emergency cooling water, RB spray, BWST level instrumentation, or cooling water systems which will not remove more than one train of each system from service. Components shall not be removed from service so that the affected system train is inoperable for more than 72 consecutive hours. If the system is not restored to meet the requirements of Specification 3.3.1 within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the reactor shall be placed in a HOT SHUTDOWN condition within six hours."

T.S. 3.3.2 requires that, when in the reactor power operation mode with the 'A' train of HPI inoperable for greater than 72 consecutive hours, the reactor shall be placed in a hot shutdown condition within six hours. This request for enforcement discretion is being made to avoid an unnecessary shutdown of the reactor without a corresponding health and safety benefit as the result of compliance with TS 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" due to the 'A' train of HPI being inoperable for greater than 72 consecutive hours. The LCO expires at 17:30 on July 13, 2014.

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Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems"

3. Provide a description of the circumstances, including as a minimum: likely causes; the need for prompt action; the action taken to avoid the need for a NOED; and any relevant historical events.

The leak was identified by an operator during a plant walk-through of the area at 17:30 on July 10, 2014. This started the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO time clock. Characterization of the leak commenced which included additional dye-penetrant examinations and personnel resources to support technical evaluation and planning activities. The station response center (Outage Control Center - OCC) was activated and has been continuously staffed.

The area of the leak was non-destructively examined (NDE) in parallel with development of a repair plan. Based upon initial NDE results, detailed work order repair activities were written and a schedule developed. The resulting schedule showed completion of the repair and return of the 'A' train of HPI to operable status to be within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO (return to service time of 17:30 on July 13, 2014).

The maintenance activity to repair the leaking welded connection has been delayed due to inadequate isolation of hot water into the repair area. The water source has been identified as through valve seat leakage from an HPI injection path isolation valve. Efforts to eliminate the through valve seat leakage were not successful. These delays have delayed the time to start repairs and necessitated the request for enforcement discretion.

The affected leak area isolation clearance boundary was established and the clearance applied. Multiple attempts using various methods were made to obtain an adequate isolation of the affected leak area to support the repair of the leak. Efforts to date include:

• Increase torque to the closed isolation boundary valves (two attempts to apply additional torque)

• Multiple attempts to apply a freeze seal (6 inch sleeve)

• Drain rig installed to seat upstream check valve

• Eductor applied to remove steam from leak repair area The current repair schedule is based on using a combination of isolation devices including a 12 inch vendor applied freeze seal and requires a 46.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> extension of the LCO timeclock to return 'A' train of HPI to operability.

Discussions with the freeze seal vendor determined that the 12 inch freeze seal for this application will be more effective in establishing a boundary. Previous attempts were made with 6 inch freeze seals that were available but were unsuccessful in the attempt to establish a boundary.

The reasons for increased confidence of success in establishing an effective boundary using the 12 inch freeze seal are as follows. Refer to Enclosure 2 "Piping and Instrumentation Diagram" where the HPI flow comes from upper left and branches to a 4 inch line and a 2 1/22 inch line. The 4 inch line reduces to a 2 1/2 inch line that goes to flow element MU-23-FE1 and then to valve MU-V-16A; this is the 'A' HPI line. The other branch is a 2 1/2 inch line that goes to flow element MU-23-FE2 and then to valve MU-V-16B; this is the 'B' HPI line. Freeze seals were applied on the 'A' HPI line upstream of the flow element MU-23-FE1 and likewise on the 'B' HPI line upstream of flow element MU FE2, each on the 2 1/2 inch diameter piping. The initial freeze seal attempt was with a 6 Page 2 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" inch freeze seal applied on the 'A' HPI line only, and it reduced fluid temperature to 72 degrees Fahrenheit (OF) in 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The second freeze seal attempt was with a 6 inch freeze seal applied on the 'A' HPI line and, the 'B' HPI line, and it reduced fluid temperature to 34 degrees Fahrenheit (°F) in 2 1/2 hours. Through monitoring of pipe temperatures and thermography it was determined that the primary problem in achieving adequate isolation was due to leakage past the valve seat of MU-V-16A. The freeze seal vendor recommended the 12 inch seal, and, coupled with the above attempts and data collected, increased confidence that the application of the 12 inch freeze seal on the 'A' HPI line (in lieu of the 6 inch freeze seal), along with the 6 inch seal on the 'B' HPI line will be successful in achieving an effective boundary.

The affected area of the leak on the 'A' train of HPI was last inspected satisfactorily via a VT-2 visual exam in 2012.

No action can be taken to remove the weld flaw and complete repair until adequate isolation can be obtained. The NDE identified 3 small weld flaws as shown in Enclosure 4.

The flaw type cannot be fully characterized using the available NDE techniques and repair methods associated with particular flaw types cannot be utilized. In 2009, a similar condition was identified and corrected on the opposite side of this pipe coupling.

Observations from the 2009 repair and subsequent evaluation concluded that the likely cause is transgranular stress corrosion cracking (TGSCC).

This weld repair will meet applicable ASME code requirements for repair and replacement.

The following immediate actions were taken upon discovery of the leak:

• The control room supervisor and shift manager were notified of the leak.

• The leak was verified to be isolable.

• The Radiation Monitoring System for the Auxiliary Building indicated that dose levels were not adversely impacted.

• Radiation Protection was notified to rope off affected areas.

• A 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Reactor Coolant System leak rate calculation was in-progress which verified the leak rate was less than TS limits.

Verified the total Auxiliary Building leakage was less than 15 gallons per hour as required per TS 4.5.4.1.

Enforcement discretion is requested to defer the required shutdown and allow continued operation of TMI, Unit 1 until these repairs can be completed. If the 'A' HPI train cannot be made operable during the requested 46.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> enforcement discretion period, TMI, Unit 1 will be placed in HOT SHUTDOWN on or before 16:00 hours on July 15, 2014.

In the event the 12 inch freeze seal is not successful at isolation, the plant will proceed to hot shutdown within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of this confirmation.

There have been no requests for NOED by Three Mile Island, Unit 1 in recent history.

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Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems"

4. Provide information that shows the Station fully understands the cause of the situation that has led to the NOED request.

As discussed in Section 3 above, the flaw type cannot be characterized using the available NDE techniques and repair methods associated with particular flaw types cannot be utilized. In 2009, a similar condition was identified and corrected on the opposite side of this pipe coupling. Observations from the 2009 repair and subsequent evaluation concluded that the likely cause is transgranular stress corrosion cracking (TGSCC).

5. Detail the proposed course of action to resolve the situation, so enforcement discretion is no longer required.

The intent is to establish a water-free environment for the weld repair to commence and complete in a satisfactory manner. In addition to the actions in progress to obtain improved isolation, the welder workmanship has been reviewed. The welder assigned is qualified for this socket connection and materials. A welding supervisor will directly observe the weld and welder during application. A station weld inspector will independently inspect the weld and associated documentation in accordance with established station procedures.

The original construction code, USAS B31.7 1968 draft with June 1968 Errata, requires a 1/16" pull-out when performing a socket weld to prevent the pipe from bottoming out after weld shrinkage. The defect will be removed from the weld by grinding leaving the remainder of the existing weld intact, the current as-built configuration will be maintained. Any additional weld shrinkage is not expected to have an impact on the existing pipe pull-out. The welding will be performed using approved WPS 8-8-GTSM that has a minimum inter-pass temperature of 350 degrees Fahrenheit while using ER308L filler metal.

After repair of the original fillet weld, a 2 to 1 fillet weld will be applied to reduce the susceptibility to future failures. The 2 to 1 fillet weld will be applied 360 degrees around the repaired weld in accordance with station procedures.

The sequence of activities to restore the 'A' train of HPI to operable status prior to 16:00 on July 15, 2014:

• Prepare pipe location for application of 12 inch freeze seal

" Install the 12 inch freeze seal

• Apply nitrogen to the 12 inch and 6 inch freeze seals

• Excavate weld

• Perform NDE of area using dye penetrant test

" Perform re-weld

• Re-weld to be examined for quality in meeting the acceptance criteria

• Remove work clearance

" Perform visual examination

• Perform Post Maintenance Testing There is a contingency built within the schedule to perform another grind and re-weld if necessary.

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Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems"

6. Explain that the resolution itself will not result in a different, unnecessary transient.

The 'A' HPI train will remain out of service an additional 46.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> based on approval of the NOED. The HPI system out of service is not a transient initiator but is relied on to mitigate design basis accidents as defined in FSAR Chapter 14 Safety Analysis for a spectrum of RCS break sizes. There are no new or different transients as a result of this extension. There is no indication of any conditions indicating a degradation of an RCS boundary such as an adverse trend in RCS leakage. The additional outage time is acceptable from a risk perspective as defined in item 12. TMI, Unit 1 has determined that there is minimal safety consequence in extending the LCO an additional 46.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The additional 46.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> will allow for repairs of the HPI line as discussed above. The repair will undergo post-maintenance testing prior to being restored to service.

7. Explain that there was insufficient time to process an emergency license amendment, or that a license amendment is not needed.

The identified weld leak was an emergent condition that results in required corrective maintenance. The initial assessment was that repairs could be made within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> TS LCO. The short duration of the identified LCO and the initial assessment of the repair did not provide indication of the need or adequate timeline to process a license amendment. This NOED will be a one-time effort to repair this condition with no permanent change required to the Operating License or the TS.

8. Describe the condition and operational status of the plant, including safety-related equipment out of service or otherwise inoperable and nonsafety-related equipment that is degraded or out of service that may have risk significance and that may increase the probability of a plant transient or may complicate the recovery from a transient or may be used to mitigate the condition.

The unit will be operating at 100% power throughout the repair window. The station risk condition is Orange due to the 'A' HPI system out of service for leak repair. No other safety related components are out of service or degraded and the 'B' HPI train is operable.

The risk is mitigated through protection of the 'B' HPI train and not performing any activities which could affect equipment that could degrade plant risk. A risk assessment has determined there is no net increase in radiological risk to the public.

During the 46.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> extension, all safety-related equipment will remain operable, and there is no non safety-related equipment degraded or out of service that may increase the probability of a plant transient, complicate the recovery from a plant transient, or be used to mitigate this condition.

9. Request a specific time period for the NOED, including a justification for the duration of the noncompliance.

TMI, Unit 1 has determined that there is minimal safety consequence of extending the TS Condition Completion Time by 46.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. This determination is based on the low probability of a combination of events that would lead to an undesirable transient. Given the low risk significance for the additional 46.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> extension and the inherent risk Page 5 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" introduced by an unnecessary shutdown of the unit, the short duration of the requested enforcement discretion is justified.

10. Detail and explain compensatory measures the plant has both taken and will take to reduce the risk associated with the specified configuration.

• The 'B' train of HPI (MU-P-1C, DC-P-1B, DR-P-1B, AND MU-V-16C/D, 1E 4KV BUS, EG-Y-1 B) has been protected in accordance with plant procedures. This means to the extent practicable and controllable, no other work will be undertaken that could jeopardize unit operation.

• Operational Risk Activities (ORAs) are not permitted (except as needed in response to emergent failures) while the repair is in progress. For example, no Engineered Safeguards Actuation System (ESAS) or Reactor Protection System (RPS) testing or maintenance will be performed.

• No unavailability of any risk significant equipment, especially in the 'B' train of HPI. No surveillances that would make equipment inoperable will be performed during the period of enforcement discretion. The 'B' train HPI has been posted as protected equipment.

" The Emergency Diesel Generators (EDGs), Station Blackout Diesel (SBO) and Switchyard shall be protected, accessible as needed in response to emergent failures or conditions that develop. No elective work on the EDGs, SBO or Switchyard permitted.

• The Load Dispatcher has been apprised of TMI, Unit 1 condition in order to prioritize and maximize grid power status.

" A compensatory action implemented is shiftly review and briefing of operator actions and response to a loss of offsite power or the 1 E Engineered Safeguards bus during the duration of the 'A' train HPI.

• Operators will conduct walk downs each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift in the Intake Pump and Screen House (IPSH) to validate no concern for safety related equipment impacts from internal flooding related events.

• Verify the Susquehanna River (at Harrisburg) Hydrograph forecast for three days does not include a prediction level that would meet entry conditions for AOP-002 (Flood). Should the condition occur during the time of extension a prompt shutdown will be initiated.

• Fire Areas:

o CB-FA-2c: Remote Shutdown Panel RS-PB Fire Event

• No maintenance to be performed on panel and detection systems are determined available in area each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift.

o CB-FA-2e: Distribution Panel EH-DPES-1 F Fire Event

• No maintenance to be performed on panel and detection systems are determined available in area each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift.

o CB-FA-3b: 1 E Switchgear fires including HEAFs

• Perform risk management actions consistent with those recommended for (a)(4).

o CB-FA-3c:

• Relay Cabinets 3A, 3C, RS-SCC-5D Fire Events

• No maintenance to be performed on panel and detection systems are determined available in area each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift. Transient Page 6 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" fires in the Southwest Corner to be mitigated by ensuring no transient combustibles each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift.

o CB-FA-3d: Panel XCR Fire Event

• Perform risk management actions consistent with those recommended for (a)(4).

o CB-FA-4b: Main Control Board Fire Event

• The Control Room is continuously manned. No additional compensatory action is required o TB-FA-SW: 1 C Switchgear High Energy Arc Fault (HEAF) Event resulting in a loss of offsite power (LOOP) and failure of the 'B' EDG.

• The following compensatory actions are established to maintain risk within normal work practice limits:

" 'B' EDG and the SBO DG to be protected.

" No electrical switching to occur in the switchgear

" Shiftly fire tour

" Walkdown and/or thermography detection for hotspots in switchgear prior to extending NOED

" Review SBO alignment procedures to power the 'E' 4160v bus each shift

11. Discuss the status and potential challenges to offsite and onsite power sources, including any current or planned maintenance in the distribution system and any current or planned maintenance to the emergency diesel generators.

All off-site and on-site power sources are currently operable with no expected outages for the duration of the repair and period of enforcement discretion. All Emergency Diesel Generators are within their surveillance testing frequency. In addition, Three Mile Island Nuclear Station, Unit 1 has verified grid/offsite power status with the transmission system operator. TMI, Unit 1 apprised the load dispatcher of the potential unit down-power in order to enable them to maximize the integrity of the remaining sources of power.

12. Include the safety basis for the request and an evaluation of the safety significance and potential consequences of the proposed course of action.

a. Use the zero maintenance PRA model to establish the plant's baseline risk and the estimated risk increase associated with the period of enforcement discretion.

For this evaluation the PRA zero-maintenance version which was adjusted to allow credit for HPI injection through HPI train 'B' from MU-P-1 B to match the current plant configuration, was used to calculate the impact. This ig not a normal maintenance alignment so therefore an application specific model was employed. The result of the 46.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> extension was an ICCDP of 1.5E-07 less than the 5E-07 acceptance criteria established in USNRC Inspection Manual 0410. In addition the ICLERP result of 1.OE-08 was less than the established acceptance criteria of 5.OE-08.

b. Discuss the dominant risk contributors (cut sets or sequences or both) and summarize the risk insights for the plant-specific configuration the plant intends to operate in during the period of enforcement discretion.

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Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" The risk insights from a review of dominant contributors were evaluated. From this review the Loss of Train 'B' Power and Internal Flooding Flood Scenario 2 Zone 1 Flood Pipe Break in NRS initiating events were identified as having increased importance.

The following compensatory measures were identified:

• Operations is currently briefing every shift on OP-TM-AOP-014, "Loss of 1E 4160V Bus" as a compensatory measure to the Loss of train 'B' Power.

• Operators will conduct walk downs each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift in the IPSH to validate no concern for safety related equipment impacts from internal flooding related events.

• No other maintenance on PRA-related equipment will be performed.

c. Discuss how the proposed compensatory measures are accounted for in the PRA.

This evaluation is based on the application specific zero-maintenance PRA model for TMI. The compensatory measures identified above limit the maintenance configuration to that of the requested NOED and highlight the importance of other systems/functions that should remain available. Since the evaluation using the application specific (discussed in a above) zero-maintenance PRA model bounds this configuration, there was no special accounting for the implementation of the compensatory measures in the PRA model.

d. 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 related PRA common cause factors have been made to account for potential increases in their failure probabilities. The method used to determine the extent of condition shall be discussed.

This NOED is requesting additional time to restore HPI train 'A'. This train is unavailable to isolate for repair of a leak of MU-V-1 034. There have been no other identified leaks in the RCS that show an indication of increased risk in other trains.

Therefore, there are no adjustments made to the base model to account for an increase in the common cause failure probability.

e. Discuss external event risks for the specified plan configuration.

Fire The site is currently implementing Risk Management Actions in the following areas to meet fire requirement for 10CFR50.65(a)(4) and will continue to do so throughout the duration of the enforcement discretion window:

• CB-FA-3B Control Building - 1 E Switchgear Room

• CB-FA-3D Control Building - Relay Room TMI has an interim Fire PRA that is not approved for numerical quantification.

However, information from the TMI Fire PRA can be used to provide insights into fire Page 8 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" risks associated with this configuration. The following compensatory measures were identified from this review.

The following fire areas have significant risk increases when comparing the base Fire PRA results with those having 'A' train HPI unavailable:

• CB-FA-2c Control Building - Tech Support Center

• CB-FA-2e Control Building - West Inverter Room

• CB-FA-3b Control Building - 1 E Switchgear Room

• CB-FA-3c Control Building - ESAS Room

• CB-FA-3d Control Building - Relay Room

• CB-FA-4b Control Building - Control Room

• TB-FA-SW Turbine Building - Non-vital Switchgear Area A review of the major scenarios in each of these fire areas was performed to gain insights and develop potential compensatory measures. The following describes the major risk and compensatory measures for each of the fire areas.

CB-FA-2c Remote Shutdown Panel RS-PB Fire Event - No maintenance to be performed on panel and detection systems are determined available in area each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift.

CB-FA-2e Distribution Panel EH-DPES-1F Fire Event - No maintenance to be performed on panel and detection systems are determined available in area each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift.

CB-FA-3b 1E Switchgear fires including HEAFs - Perform risk management actions consistent with those recommended for (a)(4).

CB-FA-3c

1. Relay Cabinets 3A, 3C, RS-SCC-5D Fire Events - No maintenance to be performed on panel and detection systems are determined available in area each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift.

2. Transient fires in the Southwest Corner - Verifying no transient combustibles in the area and performing routine tours of area each 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> shift.

CB-FA-3d Panel XCR Fire Event - Perform risk management actions consistent with those recommended for (a)(4).

CB-FA-4b Main Control Board Fire Event - The Control Room is continuously manned. There is no additional compensatory action recommended.

TB-FA-SW 1C Switchgear HEAF Event resulting in a loss of offsite power (LOOP) and failure of the B EDG.

Page 9 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" The following compensatory actions are recommended to maintain risk within normal work practice limits:

• 'B' EDG and the SBO DG should be protected.

• No electrical switching should occur in the switchgear.

• Shiftly fire tour.

• Walkdown and/or thermography detection for hotspots in switchgear prior to extending NOED.

• Review SBO alignment procedures.

Flood A limited and simplified external flood PRA was completed for the 1994 IPEEE submittal. Subsequent external flood risk studies have provided more detailed insights into the contributors to external flood risk at TMI.

• External flood risk is dominated by beyond design basis floods, (i.e., those floods greater than the Probable Maximum Flood (PMF) of 313.5' elevation). During these floods, the Flood Barrier System is overtopped and the core damage mitigation strategy relies on portable equipment -- the Severe Flood Mitigation System (SFMS). Therefore, unavailability of one train of MU has essentially no impact on the risk from floods greater than PMF, which account for approximately 80% of external flood risk.

• For external floods below the PMF, flood risk is dominated by human failures in establishing the FBS, hardware failures of the FBS (e.g., flood seal and flood gate failures), and failure of the onsite emergency electrical power system, primarily failure of the EDGs. Therefore, there is little change in the flood risk for external floods below the PMF, due to the unavailability of one train of MU.

Therefore, any increase in external flood risk due to the unavailability of MU train A is insignificant. However, the plan is to monitor for any flooding events during the extended maintenance period. The current long range forecast does not include any severe or tropical storms for the region, which could potentially result in large scale river flooding. The compensatory measure would be to:

Verify the Susquehanna River (at Harrisburg) hydrograph forecast for three days does not include a prediction level that would meet entry conditions for AOP-002 (Flood). Should the condition occur during the time of extension, a prompt shutdown will be initiated.

Seismic A seismic PRA was completed for the 1994 IPEEE submittal, which included plant-specific fragility calculations for seismically important structures, systems, and components. Although significant changes to the underlying internal events PRA model have been made since the IPEEE, the fragility information and quantification results from the IPEEE can be used to qualitatively assess the impact of the MU train

'A' unavailability.

The MU system is seismically rugged. However, fragilities for the MU pump cooling water systems are relatively low. Specifically, the DHCCW HXs and the electrical Page 10 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" buses for the river water pumps (NR and DR) have low seismic capacities. Since the seismic failure of the support systems for MU and DHR dominate the seismic risk, additional risk associated with having 'A' MU train unavailable for an additional 46.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> is not significant and does not provide any new compensatory measures beyond those already identified.

A simplified Seismic PRA was developed in 2012 using fragility information from the IPEEE, generic fragilities, the current internal events model of record, and the 2010 EPRI seismic hazard curves. The results are consistent with the IPEEE, with respect to the dominant seismic risk contributors. As a result, a review of the importance measures from this SPRA showed that all MU system basic events have Risk Achievement Worth (RAW) values below 1.1.

Therefore, it is concluded that the configuration associated with this NOED results in an insignificant increase in seismic risk.

13. Demonstrate that the NOED condition, along with any compensatory measures, will not result in more than a minimal increase in radiological risk, either in a quantitative assessment that risk will be within the normal work control levels (ICCDP less than or equal to 5E-7 and/or ICLERP less than or equal to 5E-8) or in a defensible qualitative manner.

Based on the metrics contained in Exelon procedure ER-AA-600-1046 "Risk Metrics -

NOED and LAR," Attachment 7.1, and allowing for risk due to external events and fire, the ICCDP and ICLERP values for this 46.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> extension of the LCO 3.3.2 are below the thresholds established. In addition, this change falls within the normal work controls established in accordance with 1 OCFR50.65(a)(4).

14. Discuss forecasted weather and pandemic conditions for the requested NOED period and any plant vulnerabilities related to weather or pandemic conditions.

A review of the national weather service website as of 09:45 on July 13, 2014 determined that there is a slight risk of severe weather for the requested period of enforcement discretion. A station risk evaluation was conducted for the 46.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> extension on out of service time on the 'A' train of HPI that maintained an overall ORANGE risk condition.

Additionally, evaluation of potential summer thunderstorms causing LOOP and TRIP high risk evolutions were conducted with overall station risk remaining ORANGE.

15. Include the basis for the conclusion the noncompliance will not create undue risk to public health and safety.

The proposed period of noncompliance will not be detrimental to public health and safety.

EGC has evaluated the risk and determined that it is sufficiently low. A summary of the evaluation is provided as part of item 12. To further protect the health and safety of the public, a number of risk management actions have been taken to increase operator awareness of critical equipment, to provide assurance that assumptions in the risk model are maintained, and to minimize the likelihood of a transient for the duration of the noncompliance. Refer to items 10 and 12 for compensatory actions.

Page 11 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems"

16. Include the basis for the conclusion that the noncompliance will not involve adverse consequences to the environment.

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 USNRC's granting of this request for enforcement discretion will not involve any adverse consequences to the environment.

17. Did the facility organization that normally reviews safety issues approve the request?

This request for enforcement discretion has been approved by the Three Mile Island Nuclear Station Plant Operations Review Committee (PORC) in accordance with the requirements of the station administrative procedures.

18. Did the station commit that it will submit a written NOED request within two working days and a follow-up license amendment request following the USNRC's verbal granting of the NOED?

A follow-up TS amendment is not needed because the conditions requiring the requested NOED are not typical. This request is limited due to the nature of obtaining adequate isolation to conduct repair work. EGC's decision to not submit a follow-up license amendment was discussed in a call with the USNRC on July 13, 2014.

19. Additional information for Natural Event NOEDs:

This request for Enforcement Discretion does not involve severe weather or other natural phenomena-related events; therefore, the associated Natural Event NOED questions do not apply.

Page 12 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" Enclosure 2 Piping and Instrumentation Diagram Page 13 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" Enclosure 3 Picture of Leak Leak location by dye penetrant test (see arrow in picture)

Viewing left to right: Reducer - 1/2" pipe - Valve Page 14 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Reactor Building Emergency Technical Specification 3.3.2, "Emergency Core Cooling, Cooling and Reactor Building Spray Systems" Enclosure 4 NDE Report Exeton Liquid Penetrant Examination S0teUnk TMI 1 1 Prccedura: ER-A.335,02 Wailge No: WA Summr~ey NO.1 2014-2t1-002 Psocedure Rev., 006 Ileport No.: DOP-PT-2014-ODS Workscope. BlOMlon-O'Aano Work Offtr No.: C2032503-08 Paeg I o 2 Code: Engineering Direction cetJltem: NIA Location: Aux Decay Shielded Area 5B Drawing No,: 306814 Descptioe. MU-V-1034 Inlet Pip Leak Location System FD: 211 (NPtlMakeup Puriflicaton System)

CoMpOnent it: MU-V-1034 Mll/Thitckness: 8 1 Sch, 160 LxnkatOnS: Hong Light Meter Mlg. WA Serial No: NWA tllumination: UK4AA Light Temp. Tool Mig: Fluko Serial No,: 0002608*11 Surface Tenp.: 112 IF Comparator lok Teamp : Side A: N/A IF Side 8: N/A IF Resoution: Attachment 3 L0i/o Location: WA $vriace Concdtion, Clean Developer Visible Fluorescent Rumove Cleaner Penetrant Remover Developer Brand MItgnaltux Magnaflux Magnatlux Magnaflux Type SKC-S SKL-SP2 sxKCS SKD,52 Batch NO. 09F21K 11 G05K 9F121 K 13EF2K Time Evap. 5 Min Dwell 30 Min Evep &liln Develop 10 MIn Time Exam Starled. 1130 Irme Exam Completed: 1230 kIdication Lcc Loc Diameter Length Type Remarks No, L W WL I0U0625 Rounded Located MlWeld toe @ 4 Oclock 2 0625V Rounded Locatled at Weld too @6 O'clock 3 0.12S' Linea LVShaped indication located In center of weld Uneer Was a faint Indtication located 0 8 O'clock NWE peokmued an Infomtatlional PT aonm to try and find the thru-wall leak locatiM. The PT examr showed 3 Indlceatilone (2 Rounded & I Unear). The linear indications was in the center of tMeweld and the M rounded ntdicatione were an the lee of the weld (valve slde), No indications found on pipe. See attached photo for locelons.

Resub: Accpt , ', Reject 1 into Rea:

Reufow*awPrded to eoateeiNA Percent Of Coeverage Cbtiunod D.90%: 100% Revuwed Previoew Data: WA Page 15 of 16

Three Mile Island Nuclear Station, Unit 1 Request for Enforcement Discretion for Technical Specification 3.3.2, "Emergency Core Cooling, Reactor Building Emergency Cooling and Reactor Building Spray Systems" Enclosure 4 (continued)

NDE Report

" Ex on Supplemental Report Repod No. -BOP-PT-2014-008 Summary N .: 2014-21f-002 Page: 2 of 2 Sketch a;.oPho:

tf O.*ddeaSeJWe tddP.LTMI'-faphir*'W-V-1034IAU-V-134 Phrot jpg Photo Taken Looking East and Up Page 16 of 16