ML18082A081

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Request to Extend Enforcement Discretion Provided in Enforcement Guidance Memorandum 15-002 for Tornado-Generated Missile Protection Non-conformances Identified in Response to Regulatory Issues Summary 2015-06, Tornado Missile...
ML18082A081
Person / Time
Site: Dresden  Constellation icon.png
Issue date: 03/13/2018
From: Franzen B
Exelon Generation Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
DSS-ISG-2016-01, EGM 15-002, RA01, RIS 2015-06
Download: ML18082A081 (15)
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Text

Dresden Nuclear Power Station

~:J' Exelon Generation 6500 North Dresden Road Morris, IL 60450 RA01 RIS 2015-06 EGM 15-002 DSS-ISG-2016-01 March 13, 2018 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 2 and Unit 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket No. 50-237 and 50-249

Subject:

Request to Extend Enforcement Discretion Provided in Enforcement Guidance Memorandum 15-002 for Tornado-Generated Missile Protection Non-Conformances Identified in Response to Regulatory Issues Summary 2015-06, "Tornado Missile Protection" Exelon Generation Company, LLC, (EGC) hereby requests that the NRC extend the period of Enforcement Discretion for the. Dresden Nuclear Power Station (DNPS) from June 10, 2018 to June 10, 2020 pursuant to EGM 15-002 Rev. 1. DNPS has identified 1 non-conforming condition (NCC) regarding Tornado Missile Protection {TMP) requirements affecting structures, systems and components (SSCs) within the scope of the DNPS Technical Specifications {TS).

The NCC has been documented in the EGC corrective action process in accordance with station procedures and all required notifications have been made.

DNPS has completed discovery activities in response to RIS 2015-06. A summary of the discovery methodology, scope and results is provided in the Attachment.

Consistent with the guidance provided in EGM 15-002 Revision 1 and DSS-ISG-2016-01 Revision 1, compensatory measures have been implemented for the identified NCCs affecting TS SSCs and are described in sections 5 through 7 of the Attachment. These compensatory measures will remain in place until the identified NCC is resolved.

A collective review of all compensatory measures currently in place along with expected operator actions in response to severe weather and a subsequent loss of off-site power (LOOP) has been performed and confirmed that these compensatory measures will be able to be performed in an effective manner.

We request your approval before May 24, 2018.

There are no regulatory commitments contained in this submittal.

If you have any questions concerning this submittal, please contact Christian Williams, Senior Licensing Engineer at (61 O} 765-5729 or Duane Avery, Principal Regulatory Engineer at (815) 416-2804.

Respectfully,

~.l')i-~

Bruce D. Franzen Regulatory Assurance Manager Dresden Nuclear Power Station Exelon Generation Company, LLC

Attachment:

JUSTIFICATION FOR REQUEST TO EXTEND THE EXPIRATION DATE FOR ENFORCEMENT DISCRETION REGARDING TORNADO MISSILE PROTECTION REQUIREMENTS FOR THE DRESDEN NUCLEAR POWER STATION cc: Regional Administrator - NRC Region Ill NRG Senior Resident Inspector- Dresden Nuclear Power Station NRG Project Manager for Dresden Nuclear Power Station - NRR

ATTACHMENT JUSTIFICATION FOR REQUEST TO EXTEND THE EXPIRATION DATE FOR ENFORCEMENT DISCRETION REGARDING TORNADO MISSILE PROTECTION REQUIREMENTS FOR THE DRESDEN NUCLEAR POWER STATION

1. Introduction This attachment provides the justification for the Exelon Generating Company, LLC, (EGC) request to extend the expiration date for enforcement discretion regarding tornado missile protection requirements for the Dresden Nuclear Power Station (DNPS).

In Reference 1, the NRC issued Regulatory Issue Summary (RIS) 2015-06, "Tornado Missile Protection," to, in part, remind licensees of the need to conform with a plant's current, site-specific licensing basis for tornado-generated missile protection.

In Reference 2, the NRC provided in Enforcement Guidance Memorandum (EGM) 2015-002 guidance to exercise enforcement discretion when a licensee does not comply with a plant's current site-specific licensing basis for tornado-generated missile protection.

EGM 2015-002 identified DNPS as a higher tornado missile risk site (Group A), resulting in an enforcement discretion expiration date of June 10, 2018.

EGC has completed a comprehensive tornado missile protection assessment for DNPS and has identified non-conforming conditions regarding tornado missile protection requirements. Compensatory measures were implemented to address the non-conforming conditions in accordance with regulatory guidance.

EGC is requesting an extension to the enforcement discretion expiration date to allow sufficient time to address the non-conforming conditions.

EGC plans to submit a license amendment request (LAR) to request approval for the use of the Tornado Missile Risk Evaluator (TMRE) methodology, currently under development by the industry, for evaluating the identified non-conformances.

This request to extend enforcement discretion was prepared in accordance with guidance provided in Appendix B of Revision 1 of Interim Staff Guidance DSS-ISG-2016-01 (Reference 3).

The six (6) elements of the ISG are addressed as follows:

a. Description of the non-conformances where the EGM was applied

- Section 4. RIS 2015-06 Assessment Scope and Results

b. Description of the prompt compensatory actions

- Section 5. Initial Actions

c. Description of the long-term compensatory actions

- Section 6. Long Term Compensatory Measures

RA01 ATTACHMENT Page 2 of 13

d. Assessment of all compensatory measures

- Section 7. Assessment of Long-Term Compensatory Measures Coincident with Other Operator Actions

e. Basis for the need for additional enforcement discretion time

- Section 10. Basis and Reason for Extension Request

f. Timeline for restoring compliance with the licensing basis

- Section 9. Plans for Permanent Resolution

2. RIS 2015-06 Assessment Methodology The methodology followed by EGG which was developed in response to RIS 2015-06 includes 3 objectives:

(1) Document the current facility licensing basis (CLB) for tornados and tornado missile protection (TMP)

(2) Evaluate the site's conformance with the TMP licensing basis through a design review and plant walk-downs and document any TMP nonconforming conditions (NCCs)

(3) Resolve TMP NCCs within the Corrective Action Program (CAP)

3. Summary of CLB for Tornado and Tornado Missile Protection Design The DNPS CLB for tornados and tornado missiles pertinent to RIS 2015-06 is summarized in original plant licensing documents. The documents include the original FSAR and AEC Questions and Answers applicable to tornados and tornado missile protection.

CLB for Tornado Protection Design As discussed in UFSAR section 3.3.2, the design basis tornado has a maximum combined traverse and tangential velocity of 300 miles per hour (mph) and causes a pressure drop of 6.3 pounds per square inch (psi) and results in the generation of a tornado borne missile. The CLB wind speed and the pressure drop occur simultaneously.

CLB for Tornado Missile Protection Design The DNPS CLB requires protection against two individual design basis tornado generated missiles:

  • A telephone pole 35-feet (ft.) long having a velocity of 150 mph with a butt diameter of 13-inches and unit weight of 50 pounds per cubic ft. (1,613 pounds)
  • A one-ton mass having a velocity of 100 mph with a contact area of 25 square ft.

RA01 ATTACHMENT Page 3 of 13 CLB for Safe Shutdown Equipment Dresden is licen,sed to protect against the effects of a single bounding tornado generated missile impact and not to multiple impacts by bounding missiles on the concrete structures which house equipment necessary for safe shutdown. The single missile design criterion is applicable to the Unit 2 & 3 power block; e.g., the combined Reactor Buildings and Turbine Buildings. In addition, Class I redundant systems are physically separated.

CLB References

4. RIS 2015-06 Assessment Scope and Results The assessment completed reviews and walk downs for DNPS Class 1 structures, which were designed to withstand the tornado and tornado generated missiles specified in the CLB as well non-Class 1 structures which house components important to the safe shut-down of the plant. The non-conforming conditions identified during the design reviews and walkdowns were documented in the following condition report within the corrective action program:

Main Storage Tanks Vents- Non-Conforming

5. Initial Actions The following initial actions were taken in response to the identified non-conforming conditions in accordance with EGM 15-002 and DSS-ISG-2016-'01:
a. The non-conforming conditions were reported by DNPS as an eight-hour notification on February 12, 2018 (Event Number 53204) under the following regulations:
  • 10 CFR 50.72{b){3){v)(D), "Mitigate the consequences of an accident."

The NRC resident inspector was notified.

b. Operability determinations were completed and documented in the corrective action program. The non-conforming .equipment was initially declared inoperable. Guidance in Revision 1 of EGM 15-002 (Reference 4) was used to declare the equipment operable but non-conforming and to implement enforcement discretion.
c. Licensee Event Report will be submitted in accordance with 10 CFR 50. 73 due to Technical Specification-required equipment that did not meet CLB requirements for protection against tornado missiles. The DNPS LEA is due on 4/13/2018.

RA01 ATTACHMENT Page 4 of 13

d. The following Initial compensatory measures have been verified to be in place in accordance with EGM 15-002 and DSS-ISG-2016-01 Appendix A.

1.) Verify that procedures are in place and training is current for performing actions in response to a tornado, such as:

a. The affected unit's abnormal and emergency operating procedures addressing tornados/high winds, and the loss of the tornado missile vulnerable equipment.

DNPS RESPONSE:

In the event high winds or tornado activity, the station uses severe weather emergency and abnormal operating procedures.

Dresden procedures currently implemented to address this are:

1. OP-AA-108-111-1001, Severe Weather and Natural Disaster Guidelines
2. DOA 0010-02, Tornado Waning - Severe Winds
a. NOTE: This procedure was revised to include long-term compensatory actions to address the identified NCCs, which meets the requirement for the 60-day compensatory measures.
b. The affected unit's Diverse and Flexible Coping Strategies (FLEX) equipment and procedures, if available. If site FLEX equipment and procedures are not available, specific measures should be put in place with equipment staged, procedures written, and training completed for actions to lessen the likelihood of tornado missile effects on the affected SSCs, or for prompt recovery of SSC function from tornado missile effects.

DNPS RESPONSE:

In the event high winds or tornado activity, the station uses procedures, as needed, for the use of FLEX equipment to attain and maintain shutdown conditions.

Dresden procedures currently implemented to address this are:

1. CC-AA-118, Diverse and Flexible Coping Strategy (FLEX) and Spent Fuel Pool Instrumentation Program Document
2. CC-DR-118, Site Implementation of Diverse and Flexible Coping Strategy (FLEX) and Spent Fuel Pool Instrumentation Program Document
3. FSG-36, FLEX Damage Assessment
4. FSG-03, FLEX Strategy for Supplying Power to FLEX Pumps
5. FSG-04, Aligning FLEX Pumps for Operation
6. FSG-05, FLEX Isolation Condenser Make-Up and Level Control

RA01 ATTACHMENT Page 5 of 13 2.) Verify that procedures are in place and training is current for the following actions to be taken if a tornado watch is issued for the area, such as:

a. Remove, relocate, or secure potential missiles.

DNPS RESPONSE:

In the event high winds or tornado activity is forecasted, the station performs walk downs of the site to identify items sufficient size to impact the plant structure and transmission Systems and relocates or secures the identified items to reduce potential threat that could become projectiles in high wind situations.

Dresden procedures currently implemented to address this are:

1. OP-AA-108-111-1001, Severe Weather and Natural Disaster Guidelines
2. DOA 0010-02, Tornado Waning - Severe Winds
b. From a work management/configuration control perspective, protect equipment important to maintaining safe shutdown conditions.

DNPS RESPONSE:

In the event high winds or tornado activity is forecasted, to protect equipment that is important to maintaining safe shutdown conditions, procedures direct station personnel to inspect for potential missiles and reduce potential of these missiles from causing damage to the plant structure and transmission Systems.

Procedures provide direction to evaluate for'potential loss of off-site power and update the on-line risk program as needed.

Also, station procedures provide instructions to secure work on the refuel floor, to place refuel grapple crane in a certain position, secure work that may make Engineered Safety Feature equipment inoperable, verify all access doors from outside to Unit 2 and Unit 3 Turbine and Reactor Building are secured closed, and verify Unit 3 Reactor Building material interlock inner door is closed.

Dresden procedures currently implemented to address this are:

1. OP-AA-108-111-1001, Severe Weather and Natural Disaster Guidelines
2. WC-AA-101, On-Line Work Control Process
3. WC-AA-101-1006, On-Line Risk Management and Assessment
4. DOA 0010-02, Tornado Warning - Severe Winds

RA01 ATIACHMENT Page 6 of 13

c. Promptly complete or restore equipment from maintenance ac~ivities in progress on equipment important to maintaining safe shutdown conditions.

DNPS RESPONSE:

During severe winds or a tornado event, station procedures require operators to evaluate equipment out of service to identify critical equipment to return to service. In addition, the work scheduling process requires that the risk of maintenance activities be continually assessed by plant operations.

Station procedures provide thresholds when actions are to be taken to minimize or cease plant operation, including testing or maintenance, using quantitative and qualitative considerations to ensure that station is not placed in an unacceptable risk configuration.

Dresden procedures currently implemented to address this are:

1. OP-AA-108-111-1001, Severe Weather and Natural Disaster Guidelines
2. DOA 0010-02, Tornado Waning - Severe Winds
d. Restore equipment important to maintaining safe shutdown conditions if undergoing maintenance or testing, if possible.

DNPS RESPONSE:

During severe winds or a tornado event, procedures require the station to evaluate equipment out of service to identify critical equipment to return to service. In addition, the work scheduling process requires that the risk of maintenance activities be continually assessed by plant operations.

Dresden procedures currently implemented to address this are:

1. OP-AA-108-111-1001, Severe Weather and Natural Disaster Guidelines
2. DOA 0010-02, Tornado Waning - Severe Winds
e. Verify equipment is ready to use by visual inspection, surveillances and preventive maintenance are current, and review pending equipment maintenance requests.

DNPS RESPONSE:

All safety equipment deficiencies are tracked in the Degraded Equipment Log and reviewed by all Licensed Operators on shift. Equipment is verified ready for use by Operator rounds. Work control schedules and monitors surveillance tests and preventative maintenance tasks appropriately to ensure no past due surveillances exceed Tech Spec timeclocks. The work scheduling process requires that the plant configuration risk due to equipment removed from service for maintenance activities to be continually assessed by plant operations.

RA01 ATTACHMENT Page 7 of 13 In the event high winds or tornado activity is forecasted, the station procedures provide directions to verify equipment (e.g., Diesel Generators) is available then restored to operable status, if practicable.

Dresden procedures currently implemented to address this are:

1. OP-AA-102-102, General Area Checks and Operator Field Rounds
2. OP-AA-108-111-1001, Severe Weather and Natural Disaster Guidelines
3. OP-AA-112-101, Shift Turnover and Relief
4. WC-AA-101, On-Line Work Control Process
5. WC-AA-101-1006, On-Line Risk Management and Assessment
6. WC-AA-107, Seasonal Readiness
7. WC-AA-111, Surveillance Program Requirements
8. DOA 0010-02, Tornado Waning - Severe Winds 3.) Verify that procedures are in place and training is current for actions to be taken if a tornado warning is issued for the area, such as:
a. Warning and protection strategies for site personnel.

DNPS RESPONSE:

In the event of a tornado warning, procedures require the operators to announce the threat over the public-address system to notify plant personnel to seek shelter indoors.

The procedures provide direction to sound the assembly siren in the event of a tornado. To supplement the plant paging system in areas where the page is known to be weak or inaudible, the station Security personnel are utilized to locate and contact personnel in those areas (e.g.

trailers and out-buildings).

In the event of a tornado condition that may require assembly of personnel to ensure their safety, facilities are utilized based on their ability to shelter personnel from the hazard being faced.

Dresden procedures currently implemented to address this are:

1. OP-AA-108-111-1001, Severe Weather and Natural Disaster Guidelines
2. DOA 0010-02, Tornado Waning - Severe Winds

RA01 ATTACHMENT Page 8 of 13

b. Strategies for prompt damage assessment and initiation of restorative actions (e.g., pre-staging of equipment and plant staff at safe, strategic locations to promptly implement any necessary mitigative actions).

DNPS RESPONSE:

In the event that a tornado impacts the site, once the tornado has passed, procedures direct the station to initiate recovery actions and to inspect site interior and exterior areas. Within one hour following high winds or a tornado event, required actions include visually inspecting areas known to be susceptible for tornado-generated missiles, such as the EDG intake, exhaust and the fuel oil storage tank vent piping for damage.

Dresden procedures currently implemented to address this are:

1. DOA 0010-02, Tornado Waning - Severe Winds
2. FSG-36, FLEX Damage Assessment 4.) Establish a heightened level of station awareness and preparedness relative to identified tornado missile vulnerabilities. This can be accomplished by including:
a. A description of the nonconforming SSC(s) and the associated compensatory measures in the shift manager turnover notes.

DNPS RESPONSE:

DNPS implements this through Shift Manager Turnovers.

b. Discussing these actions during shift turnover briefings.

DNPS RESPONSE:

DNPS implements this through Shift Manager Turnovers Checklists.

c. Including the compensatory actions in the operability determination documentation maintained in the control room.

DNPS RESPONSE:

Compensatory actions are maintained in the Main Control Room.

When local severe weather is identified, the station maintains a heightened awareness of rapid changing weather conditions. The station performs subsequent actions include deferring any evolution which increases risk. Nonconforming structures, systems, and components (SSC) and associated compensatory measures are discussed during Main Control Room turnovers. Standing Order 18-001 is maintained in Dresden Main Control Room.

RA01 ATTACHMENT Page 9 of 13 Diesel Generator Main Fuel Oil Storage Tank Vents DOA 0010-2 was revised to address the exposed fuel oil storage tank vents by repairing or removing any vent obstructions following a tornado event.

General procedural guidance: Dresden Abnormal Operating Procedure (DOA 0010-02, 11 Tornado Waning - Severe Winds," provides procedural requirements in reparation/response to a tornado.

6. Long-Term Compensatory Measures As long-term comprehensive compensatory measures, the following procedures were revised as described:
a. DOA 0010-02 was revised to include the exposed diesel generator fuel main storage tank vent piping as a possible component that could be damaged during a high wind or tornado event. The compensatory measure incorporated in the revision to DOA 0010-02 verifies that the vent lines for the EOG main fuel oil storage tanks are not crimped within one hour following high winds or a tornado event.

If the vent lines are crimped, the procedure directs the station to immediately repair or remove the obstruction. These steps would be performed during the visual inspections of the EOG exhaust and intake that are already required by the procedure.

These long-term comprehensive compensatory measures are in accordance with EGM 15-002 and Interim Staff Guidance DSS-ISG-2016-01, and will remain in-place until the non-conformances are resolved.

7. Assessment of Long-Term Compensatory Measure Coincident with Other Operator Actions The above long-term compensatory measures established to address the non-conforming conditions and other expected operator actions in response to severe weather and a subsequent loss of off-site power (LOOP) were collectively assessed.

This assessment considered the timing and duration of the operator actions specified within the compensatory measures coincident with the other actions the operators may need to perform in response to a severe weather LOOP event.

The compensatory measure incorporated in the revision to DOA 0010-02 verifies that the vent lines for the EOG main fuel oil storage tanks are not crimped within one hour following high winds or a tornado event. If the vent lines are crimped, the procedure directs the station to immediately repair or remove the obstruction. These steps would be performed during the visual inspections of the EOG exhaust and intake that are already required by the procedure.

The guidance added to the basis documents for DOA 0010-02 does not contain any additional operator actions.

The operator actions credited as long-term compensatory measures in the operating procedure revisions are limited and were determined to have minimal impact on other operator actions that may be needed.

RA01 ATTACHMENT Page 10 of 13 The assessment concluded that the implemented long-term compensatory measures along with other beneficial actions in a severe weather LOOP event can be completed without putting unnecessary burden on the operators.

A review of time-critical actions/time-sensitive actions (TCAs/TSAs) was also performed.

TCAs/TSAs that occur outside of the control room and that are plausibly necessary concurrent with a high winds/tornado event includes station battery load stripping for station blackout events, cross-tying electrical buses as needed, and local manual operation of isolation condenser and HPCI. No detrimental effects were identified.

These items are trained on a recurring frequency. Operators are proficient with performing these tasks.

8. Site procedural guidance for the equipment non-conformances listed in Section 4 is described below:

Emergency Diesel Generator Support Systems Non-Conformance The vent lines for each of the EDG main fuel oil storage tanks are unprotected, and a missile impact could crimp the vent lines, preventing fuel oil transfer from the main tank to the EDG day tanks.

Procedural Guidance:

Procedure DOA 0010-02 directs the station to visually inspect the main fuel oil storage tanks vents to assess for damage following a tornado event. In the unlikely event that a vent line is crimped, the procedure instructs the station immediately repair or remove the obstruction.

Additional Discussion The operators maintain cognizance of the tornado-generated missile protection non-conformances by reviewing a report of plant non-conformances every shift, as required by site procedures.

Operator actions to address plant conditions resulting from the tornado-generated missile protection non-conformances are contained within plant operating procedures, as discussed above. Operator cognizance of these procedural actions is ensured via initial and continuing operator training, which includes reviews of procedural guidance for acts of nature.

DNPS is in compliance with NRC Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events. This Order directed licensees to develop and implement (FLEX) strategies and guidance to maintain or restore core cooling, containment cooling, and spent fuel pool cooling capabilities in the event of a beyond-design-basis external event in which ac power and normal access to the ultimate heat sink are lost. DNPS has implemented procedures which use equipment staged within a tornado missile protected building to respond to such an event. The FLEX procedures and equipment would be available to address plant conditions resulting from the tornado missile protection non-conformances, in addition to the operator actions described in the procedural guidance above.

RA01 ATIACHMENT Page 11 of 13

9. Plans for Permanent Resolution EGC will be submitting a License Amendment Request to incorporate the results of the TMRE analysis once the TMRE methodology is approved and finalized.

If the TMRE analysis methodology or results for DNPS are determined to be unacceptable, permanent resolution will be reevaluated to consider either the previously approved TORMIS methodology, Plant Design Changes, or a combination of plant design changes and TORM IS or TMRE.

10. Basis and Reason for Extension Request In EGM 2015-002 (Reference 2), the NRC provided guidance to exercise enforcement discretion when an operating power reactor licensee does not comply with a plant's current site-specific licensing basis for tornado-generated missile protection. The NRC would exercise this enforcement discretion only when a licensee implements initial compensatory measures to provide additional protection, followed by more comprehensive, long-term compensatory measures implemented within 60 days of issue discovery. The enforcement discretion would expire three years after issuance of RIS 2015-06, dated June 1O, 2015, for plants of a higher tornado missile risk (Group A Plants), and five years after RIS issuance for plants of a lower tornado missile risk (Group B Plants). EGM 2015-002 identified DNPS as a plant of a higher tornado missile risk; therefore, its enforcement discretion would expire on June 10, 2018.

In Reference 4, the NRC issued Revision 1 of EGM 2015-002, which stated that licensees may request an extension to their enforcement discretion expiration date if proper justification is provided. This extension would be granted on a case-by-case basis.

In accordance with the revised EGM 15-002, EGC is requesting an extension of the expiration date for enforcement discretion at DNPS from June 10, 2018 to June 10, 2020.

There is no undue risk associated with this requested extension of the enforcement discretion due date. The identified non-conformances involve limited exposure of equipment to tornado missiles, and, in many of the non-conformances, the equipment is partially protected. In addition, tornado missile scenarios generally do not represent a significant safety concern because their risk is bounded by the initiating event frequency.

A comprehensive assessment of the site regarding tornado missile protection against the current licensing basis has been completed, revealing the non-conformances discussed above. The compensatory actions implemented for the non-conformances are consistent with the guidance in EGM 15-002 and Interim Staff Guidance DSS-ISG-2016-01, and provide assurance that the consequences of the identified non-conformances are minimized until permanently resolved. Additionally, a collective review was performed to confirm that the site operators can perform the long-term compensatory measures coincident with other actions they may need to perform in a severe weather LOOP event without putting unnecessary burden on the operators.

These compensatory measures would remain in-place throughout the period of extended enforcement discretion, until the non-conformances are resolved.

RA01 ATTACHMENT Page 12 of 13 The TMRE methodology is being developed by the industry to evaluate tornado missile.

protection non-conforming conditions. LARs for implementation of the TMRE methodology at several pilot sites are being submitted, with NRC approval of the pilot site LARs not expected until 2018. Once the pilot site LARs have been approved, then other licensees with identified tornado missile protection non-conformances would submit LARs, based on the approved pilot LARs, for implementation of the TMRE methodology to address the non-conformances at their sites.

To address the tornado missile protection non-conformances identified at DNPS, EGC would need to perform a TMRE analysis for the non-conformances, and prepare and submit a LAR for use of the TMRE methodology to evaluate the non~conformances. The DNPS LAR would be submitted after the LARs for the pilot sites have been approved. If the TMRE methodology did not resolve all of the non-conformances at DNPS, then the use of the TORMIS methodology and/or the installation of plant modifications would need to be pursued. This would all need to be completed by the current enforcement discretion expiration date of June 10, 2018. Since NRC approvals of the pilot site LARs are not expected until sometime in 2018, EGC actions to resolve the non-conformances at DNPS cannot be reasonably implemented in an orderly and cost-effective manner in the time remaining under the existing enforcement discretion.

The requested enforcement discretion expiration date of June 10, 2020 would allow EGC sufficient time to resolve the tornado missile protection non-conformances and restore the site to compliance. EGC expects that the TMRE analysis will resolve all of the identified non-conformances at DNPS. The requested enforcement discretion expiration date of June 10, 2020 would provide sufficient time for EGC to perform a TMRE analysis for the non-conformances, and to submit a LAR for implementation of the TMRE methodology at DNPS. EGC has begun performing walkdowns in support of the TMRE analysis, and plans to submit the TMRE LAR in 2019, pending approval of the pilot plant TMRE LARs. If, while performing the TMRE analysis, EGC unexpectedly determines that not all of the non-conformances will be resolved by the TMRE analysis, EGC would have sufficient time before the requested enforcement discretion expiration date of June 10, 2020 to pursue the use of the TORMIS methodology and/or install plant modifications, as discussed above, to resolve the non-conformances.

If conditions arise such that achieving tornado missile protection compliance at DNPS within the requested extended period of enforcement discretion is not possible, the NRC would be promptly notified.

RA01 ATTACHMENT Page 13 of 13

11. References
1. NRG Regulatory Issue Summary 2015-06, Tornado Missile Protection, dated June 1O, 2015 (ADAMS Accession Number ML15020A419)
2. NRG memorandum, Enforcement Guidance Memorandum 15-002, Enforcement Discretion for Tornado Generated Missile Protection Non-Compliance, dated June 10, 2015 (ADAMS Accession Number ML15111A269)
3. NRG Interim Staff Guidance, DSS-ISG-2016-01, "Clarification of Licensee Actions in Receipt of Enforcement Discretion Per Enforcement Guidance Memorandum EGM 15-002, Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance," Revision 1, dated November 2017 (ADAMS Accession Number ML17128A344)
4. NRG memorandum, Enforcement Guidance Memorandum 15-002, Revision 1:

Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance, dated February 7,2017 (ADAMS Accession Number ML16355A286)

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