ML11280A271

Request for Enforcement Discretion

ML11280A271
Person / Time
Site:	Calvert Cliffs
Issue date:	10/05/2011
From:	Spina J Constellation Energy Group, Calvert Cliffs, EDF Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML11280A271 (8)

Text

James A. Spina Calvert Cliffs Nuclear Power Plant, LLC Vice President 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410.495.5200 410.495.3500 Fax CENGSM a joint venture of O Constellation tEnergy-eDF CALVERT CLIFFS NUCLEAR POWER PLANT October 5, 2011 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:

Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit Nos. 1 and 2; Docket Nos. 50-317 and 50-318 Request for Enforcement Discretion On October 3, 2011, Calvert Cliffs Nuclear Power Plant requested enforcement discretion from the shutdown time requirements of Calvert Cliffs Technical Specification Limiting Condition for Operation 3.0.3. Unit 1 and Unit 2 were at full power at the time of the verbal request and Diesel Generators No. 1A and 2A were inoperable for different reasons. The I A Diesel Generator battery charger was unable to perform its function and the cause was unknown at the time of the verbal request. The 2A Diesel Generator was inoperable due to scheduled maintenance work on the No. 21 Saltwater Subsystem (its cooling source). The inoperability of the "A" train diesel generators on both Units at the same time caused the "A" train station battery chargers to become inoperable on both Units. Technical Specification 3.8.4, DC Sources - Operating, contains Required Actions if one channel of DC electrical sources is inoperable. With this condition, two channels of DC electrical sources were inoperable on each Unit.

With no Required Action specific to two inoperable channels, Technical Specification 3.0.3 was entered on both Units at 1035 on October 3, 2011.

At the time of the verbal request, troubleshooting was underway on the IA Diesel Generator battery charger to determine the cause of the inoperability. Its return to service was unknown. Efforts were underway to restore the No. 21 Saltwater Subsystem to operable status to support returning the 2A Diesel Generator to operable status. The estimated time of completion was 0200 on October 4, 2011. In fact, the IA Diesel Generator battery charger was returned to an operable condition at 1605 on October 3, 2011 and Technical Specification 3.0.3 was exited for both Units.

The details contained in this letter were discussed with the Nuclear Regulatory Commission staff in a phone call at 1315, October 3, 2011. Enforcement discretion was denied at the conclusion of that phone call. This letter documents the information provided to the staff during that phone call.

4o00/

Document Control Desk October 5, 2011 Page 2 A discussion of the circumstances that led to this request and the safety basis for the request is contained in Attachment (1).

Should you have questions regarding this matter, please contact Mr. Douglas E. Lauver at (410) 495-5219.

Very truly STATE OF MARYLAND TO WIT:

COUNTY OF CALVERT I, James A. Spina, being duly sworn, state that I am Vice President - Calvert Cliffs Nuclear Power Plant, LLC (CCNPP), and that I am duly authorized to execute and file this response on behalf of CCNPP. To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other CCNPP employees and/or consultants.

Such information has been reviewed in accordance with company practice and I believe it to be reliable.

Subscribed nd sworn before me, a Notary Public in and for the State of Maryland and County of

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.WITNESS my Hand and Notarial Seal:

Notary Public My Commission Expires:

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Date JAS/PSF/bjd

Attachment:

(1)

Description of Circumstances and Safety Basis cc:

D. V. Pickett, NRC Resident Inspector, NRC W. M. Dean, NRC S. T. Gray, DNR

ATTACHMENT (1)

DESCRIPTION OF CIRCUMSTANCES AND SAFETY BASIS Calvert Cliffs Nuclear Power Plant, LLC October 5, 2011

ATTACHMENT (1)

DESCRIPTION OF CIRCUMSTANCES AND SAFETY BASIS The criteria for evaluating a request for a Notice of Enforcement Discretion are contained in Reference 1.

Each of the criteria is addressed below.

Criteria 1: The TS or other license conditions that will be violated.

Calvert Cliffs Nuclear Power Plant (Calvert Cliffs) requested enforcement discretion from the shutdown time requirements of Calvert Cliffs Technical Specification Limiting Condition for Operation (LCO) 3.0.3. Limiting Condition for Operation 3.0.3 requires that when an associated Action is not provided in a Technical Specification, the Unit shall be placed in a Mode in which the LCO is not applicable. The Technical Specification of concern was 3.8.4, "DC Sources - Operating", which is applicable in Modes I though 4. Therefore, LCO 3.0.3 would require that the affected Units 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 Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

This request for enforcement discretion is being made to avoid an unnecessary plant transient as the result of compliance with Technical Specification LCO 3.0.3.

Diesel Generators (DGs) IA and 2A were inoperable for different reasons. The IA DG battery charger was unable to perform its function and the cause was unknown at the time of the verbal request. The 2A DG was inoperable due to scheduled maintenance work on the No. 21 Saltwater Subsystem (its cooling source). The inoperability of the "A" train DGs on both Units at the same time caused the "A" train station battery chargers to become inoperable on both Units. Technical Specification 3.8.4, DC Sources - Operating, contains Required Actions if one channel of DC electrical sources is inoperable.

With this condition, two channels of DC electrical sources were inoperable on each Unit. With no Required Action specific to two inoperable channels, Technical Specification LCO 3.0.3 was entered on both Units at 1035 on October 3,2011.

Therefore, we requested enforcement discretion to allow Calvert Cliffs to not comply with the shutdown time requirements of LCO 3.0.3 for a maximum of 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />. This enforcement discretion would have allowed an extension of the shutdown time requirements for Mode 3 entry from 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />, ending no later than 0200 on October 4, 2011. Note that repairs to the I A DG were completed and it was returned to operable status at 1605 on October 3, 2011.

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

Background

Calvert Cliffs is a two-unit site. Each Unit's Emergency Safety Features electrical system relies on two safety-related DGs.

In addition, there is a non-safety-related, augmented quality, station blackout 5400 kW DG available (OC DG). The IA DG and OC DG are Societe Alsacienne De Constructions Mecaniques De Mulhouse (SACM) DGs. The 2A DG is a Fairbanks-Morse DG.

Plant Condition On October 3, 2011, scheduled preventative maintenance of the No. 21 Saltwater Subsystem was underway. Technical Specification 3.8.1, Condition B, was entered for the 2A DG at 0001 on October 3, 2011 because the No. 21 Saltwater Subsystem provides a cooling function for the 2A DG. Also on October 3, 2011, the weekly battery inspection for the 1A DG was performed. During this inspection, an adjustment was made to the battery charger which resulted in the battery charger failing. This caused the 1A DG to become inoperable. The failure of the battery charger on the IA DG was unexpected because this inspection is performed weekly and this adjustment had been successfully performed in the past.

With this condition (both "A" train DGs inoperable), two channels of DC electrical sources were inoperable on each Unit because the battery chargers were not connectable to a DG within two hours.

I

ATTACHMENT (1)

DESCRIPTION OF CIRCUMSTANCES AND SAFETY BASIS With no Required Action specific to two inoperable channels, Technical Specification 3.0.3 was entered on both Units at 1035 on October 3, 2011.

The IA DG has been repaired and Technical Specification 3.8.1.B was exited at 1605 on October 3, 2011. Restoration of an "A" train DG provided the required DG power to the station battery chargers and allowed the Units to exit LCO 3.0.3.

Likely Cause The 2A DG was in a routine, scheduled maintenance window, and was not the cause of this event. The weekly battery inspection on the IA DG was also a routine, scheduled maintenance activity.

The adjustments made during the inspection likely caused a failure of the I A DG battery charger circuit cards.

An investigation of the cause of the circuit card failure is ongoing. The failed circuit cards have been replaced and the new cards successfully tested.

Criteria 3: Information to show that the cause and proposed path to resolve the situation are understood by station personnel, such that there is a high likelihood that planned action to resolve the situation can be completed within the proposed NOED timeframe.

At the time of the verbal request, the planned success path was to restore the No. 21 Saltwater Subsystem from its maintenance configuration back to an operable status. That would allow the 2A DG to be declared operable and able to support the "A" train station battery chargers. Restoration of a Saltwater Subsystem from a planned maintenance configuration is a routine, proceduralized process performed following each Saltwater Subsystem maintenance window. Although the restoration work was being performed on a shortened time schedule, the required equipment and trained personnel were available to perform this routine task. Given the station's experience with this work, the likelihood was high that the work could be accomplished in the requested timeframe.

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

Risk Insights The effect of remaining in Mode 1 for this extended time was evaluated using risk insights. The Unit 1 risk of operating for 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> with the IA DG inoperable and the "A" train station battery chargers inoperable was determined using a zero maintenance model (EOOS). Using the plants' zero maintenance model, the Incremental Conditional Core Damage Probability (ICCDP) and Incremental Conditional Large Early Release Probability (ICLERP) should not exceed 5E-7 and 5E-8. During the verbal request, the ICCDP was reported as 1.1 OE-6 for a five hour extension. This did not meet the recommended threshold.

Subsequent to the verbal request, it was determined that Unit 1 would not have reached the prescribed ICCDP and ICLERP thresholds until 16 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into the configuration where the IA DG was inoperable, along with the 2A DG inoperable (due to No. 21 Saltwater Subsystem maintenance).

Our zero-maintenance model does not include fire events. It was noted during the verbal request that there are some compensatory measures that could be taken to mitigate fire risk (i.e., fire watches in Turbine Building and hot work not allowed). Additionally, it was noted during the verbal request that flooding and seismic events were not significant contributors to the risk in this configuration.

During the verbal request compensatory actions were not identified that would reduce the probabilistic risk assessment risk increase to essentially zero.

2

ATTACHMENT (1)

DESCRIPTION OF CIRCUMSTANCES AND SAFETY BASIS Criteria 5: The *ustification for the duration of the noncompliance.

At the time of the verbal request, the planned success path was to restore the No. 21 Saltwater Subsystem from its maintenance configuration back to an operable status. That would allow the 2A DG to be declared operable and able to support the "A" train station battery chargers. Restoration of a Saltwater Subsystem from a planned maintenance configuration is a routine, proceduralized process performed following each Saltwater Subsystem maintenance window.

The restoration activities began at approximately 1400 on October 3, 2011 and were scheduled to be complete and the DG declared operable by 0200 on October 4, 2011.

To allow time to perform the restoration activities, Calvert Cliffs requested enforcement discretion in the form of a one-time, 15 hour1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> extension to the shutdown time requirements of LCO 3.0.3.

Without this discretion, shutdown preparation activities for both Units began by 1135 and the Units commenced shutdown at approximately 1350 on October 3, 2011. The lA DG was returned to operable status at 1605 on October 3, 2011 and the associated Technical Specification Condition was exited.

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

Unit 1 At the time of the verbal request, Unit I was at 100% power. The IA DG was inoperable due to an inoperable battery charger. The "A" train station battery chargers were inoperable due to no DG backup power. A high pressure safety injection train was out-of-service due to a failed check valve.

Unit 2 At the time of the verbal request, Unit 2 was at 100% power. The No. 21 Saltwater Subsystem was out-of-service for scheduled preventative maintenance.

This Saltwater Subsystem supports "A" train engineered safety features components. This impacts the following equipment: 2A DG, "A" train high and low pressure safety injection, "A" train containment spray, "A" train containment air coolers, and the "A" train component cooling water system.

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

At the time of the verbal request, four offsite power sources were available. One operable DG per Unit was also available. In addition, the station blackout DG (OC DG) was available and aligned to supply the No. 21 4 kV safety-related bus. Review of the local weather conditions for the 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> following the verbal request resulted in a determination that calm, stable conditions were expected and that minimized the possibility that a loss of offsite power could occur due to weather related conditions. In addition, the grid operator was contacted and provided no indication of potential grid anomalies that would compromise the reliability of the system during this period.

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

Calvert Cliffs Nuclear Power Plant (Calvert Cliffs) requested enforcement discretion from the shutdown time requirements of Calvert Cliffs Technical Specification Limiting Condition for Operation (LCO) 3.0.3.

Limiting Condition for Operation 3.0.3 requires that when an associated Action is not provided in a Technical Specification, the Unit shall be placed in a Mode in which the LCO is not applicable.

The Technical Specification of concern was 3.8.4, "DC Sources - Operating", which is applicable in Modes 1 though 4. Therefore, LCO 3.0.3 would require that the affected Units 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 Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. This request for enforcement discretion is being 3

ATTACHMENT (1)

DESCRIPTION OF CIRCUMSTANCES AND SAFETY BASIS made to avoid an unnecessary plant transient as the result of compliance with Technical Specification LCO 3.0.3. Calvert Cliffs wished to extend the shutdown time by 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />. The additional time was needed to restore the 2A DG to operable status.

The proposed enforcement discretion has been evaluated against the standards in 10 CFR 50.92 and has been determined to not involve a significant hazards consideration, in that operation of the facility during the period of the enforcement discretion:

I.

Would not involve a significant increase in the probability or consequences of an accident previously evaluated.

The diesel generators (DGs) provide onsite electrical power to vital systems should offsite electrical power be interrupted. Both Calvert Cliffs Units have two safety-related DGs. The DGs are not an initiator to any accident previously evaluated. Each Calvert Cliffs Unit also has four DC Source channels. The DC Source channels are also not an initiator to any accident previously evaluated.

Therefore, the extended period of operation with two DC Source channels inoperable per Unit will not increase the probability of an accident previously evaluated.

The DGs and the DC Source channels act to mitigate the consequences of design basis accidents that assume a loss of offsite power.

For that purpose, redundant DGs and DC Source channels are provided to protect against a single-failure. During the Technical Specification 72-hour Completion Time for the DGs, an operating unit is allowed by the Technical Specifications to remove one of the DGs from service, thereby losing this single-failure protection.

This operating condition is considered acceptable. The consequences of a design basis accident coincident with a failure of the redundant DG during the period of Technical Specification non-compliance are the same as those during the 72-hour Completion Time. However, a loss of two DC Source channels is outside of the Technical Specification Actions, thereby requiring entry into Technical Specification LCO 3.0.3.

This condition could increase the consequences of a design basis accident during this time. The core damage risk is not increased above the threshold value of 5E-7 for the requested 15 hour1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> extension time requested. Therefore, during the period of non-compliance, there is no significant increase in consequences of an accident previously evaluated.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2.

Would not create the possibility of a new or different type of accident from any accident previously evaluated.

During the period of non-compliance with the Technical Specifications, the plant will not be in a new configuration nor will any unusual operator actions be required. The DGs and DC Source channels are not an initiator to any accident, but are designed to respond should an accident occur.

Therefore, the proposed change does not create the possibility of a new or different type of accident from any accident previously evaluated.

3.

Would not involve a significant reduction in a margin of safety.

During the requested 15 hour1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> period when two DC Source channels are inoperable during power operation, the margin of safety is reduced. The core damage risk is not increased above the threshold value of 5E-7 for the requested 15 hour1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> extension time requested. Calvert Cliffs has determined that the possibility of a loss of offsite power is minimized due to favorable weather conditions. Calvert 4

ATTACHMENT (1)

DESCRIPTION OF CIRCUMSTANCES AND SAFETY BASIS Cliffs concludes that the period of non-compliance with the Technical Specifications beyond that allowed by LCO 3.0.3 does not result in a significant further reduction in the margin of safety.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Criteria 9:

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

Operation of Calvert Cliffs Units 1 and 2 during the period of non-compliance with the Technical Specifications would have resulted in no adverse consequences to the environment in that there were no significant change in the types or significant increases in the amounts of any effluents that may be released offsite, and in no significant increase in individual or cumulative occupational radiation exposure.

Criteria 10: A statement that the PORC has reviewed and concurs with the request.

At the time of the verbal request, the Plant Operations Review Committee had not reviewed this request.

Subsequent to the verbal request, the Plant Operations Review Committee reviewed the request and determined that the risk assessment available at the time of the verbal request did not meet the risk threshold recommended by the NRC.

Criteria 11: Which of the NOED criteria for appropriate plant conditions is satisfied and how it is satisfied.

This request for enforcement discretion is being made to avoid an unnecessary plant transient as the result of compliance with Technical Specification LCO 3.0.3. At the time of the verbal request, Units 1 and 2 were at full power and IA and 2A DGs were inoperable for different reasons.

Criteria 12: Unless otherwise agreed to by the NRC. a reiulatory commitment is required that the written NOED request will be submitted within two working days and the follow-up License Amendment Request will be submitted within 4 working days of the verbal approval of the NOED.

This letter fulfills the requirement for submission of a written request within two working days.

Requesting a license amendment would not be practical because the plant will be returned to compliance with the Technical Specifications before a license amendment could be issued. The Nuclear Regulatory Commission concurred with this assessment.

Criteria 13: Provide details for severe weather or other natural phenomena-related NOEDs.

We are not requesting enforcement discretion for a severe weather condition.

REFERENCE

1.

NRC Regulatory Issue Summary 2005-01:

Changes to Notice of Enforcement Discretion Processes and Staff Guidance, dated February 7, 2005 5