ML082340049

Request for Enforcement Discretion for Technical Specifications (TS) 3.4.4, RCS Operational Leakage and TS 3.4.5, RCS Leakage Detection Instrumentation

ML082340049
Person / Time
Site:	Dresden
Issue date:	08/19/2008
From:	Wozniak D Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SVP LTR 08-0046
Download: ML082340049 (7)

Text

Exelon.

Exelon Generation Company, LLC www.exeloncorp.com Nuclear Dresden Nuclear Power Station 6500 North Dresden Road Morris, IL 60450-9765 SVP LTR 08-0046 August 19, 2008 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 3 Renewed Facility Operating License No. DPR-25 NRC Docket No. 50-249

Subject:

Request for Enforcement Discretion for Technical Specifications (TS) 3.4.4, "RCS Operational Leakage" and TS 3.4.5, "RCS Leakage Detection Instrumentation" On August 17, 2008, Exelon Generation Company, LLC (EGC) verbally requested a Notice of Enforcement Discretion (NOED) associated with Technical Specification (TS) 3.4.4, "RCS Operational Leakage" and TS 3.4.5, "RCS Leakage Detection Instrumentation" for Dresden Nuclear Power Station (DNPS), Unit 3. The following information was discussed with representatives of the NRC on August 17, 2008 at 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br />, with subsequent approval being verbally granted by the NRC at 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br />.

On August 16, 2008 at approximately 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, Operations personnel attempted to pump the Unit 3 drywell floor drain sump, which is used to partially satisfy Surveillance Requirement (SR) 3.4.4.1. The pumps started as expected, however, the floor drain sump flow integrator indicated no flow. During a second attempt, Operations personnel observed the position of the isolation valves. The valves were observed to be in their proper indicated position. The pump breakers were inspected locally and pump motor amps were checked and no abnormalities were observed. Since the drywell floor drain sump could not be pumped, the plant was not able to satisfactorily complete SR 3.4.4.1. The sumps had been successfully pumped previously at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on August 16, 2008.

Troubleshooting was performed to identify the possible malfunction. Based on the troubleshooting, it appeared that the 3-2001-105 containment isolation valve failed closed.

EGC has determined that the portion of the system requiring repairs is part of primary containment. Therefore, repairs to the system cannot be made with Unit 3 online. EGC plans to repair the system during the next Unit 3 outage of sufficient duration, but no later than startup from the next Unit 3 refueling outage (i.e., D3R20) currently planned for November 2008.

Without approval of this NOED, Unit 3 would have had to unnecessarily shut down. The approved NOED provided a seven-day extension to the TS Completion Times to place the unit in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. This extension provided sufficient time

August 19, 2008 U.S. Nuclear Regulatory Commission Page 2 to reconfigure the drywell floor drain sump monitoring system such that the drywell equipment drain sump monitoring system could be used to quantify unidentified drywell leakage. In addition, the seven-day extension provided sufficient time to request, and the NRC to process an emergency license amendment request.

The attached enclosure provides the following information necessary for approval of the requested enforcement discretion.

There are no regulatory commitments contained in this letter.

Please address any comments or questions regarding this matter to Mr. Stephen Taylor at 815-416-2800.

Respectfully, David B. Wozniak Site Vice President Dresden Nuclear Power Station

Enclosure:

Request for Enforcement Discretion for Technical Specification 3.4.4, "RCS Operational Leakage" and TS 3.4.5, "RCS Leakage Detection Instrumentation" cc:

Regional Administrator - NRC Region III NRC Senior Resident Inspector - Dresden Nuclear Power Station NRC Project Manager - NRR - Dresden Nuclear Power Station

ENCLOSURE Dresden Nuclear Power Station (DNPS), Unit 3 Docket No. 50-249 Renewed Facility Operating License No. DPR-25 Request for Enforcement Discretion for Technical Specification 3.4.4, "RCS Operational Leakage" and TS 3.4.5, "RCS Leakage Detection Instrumentation"

Request for Enforcement Discretion for Technical Specification 3.4.4, RCS Operational Leakage and TS 3.4.5, RCS Leakage Detection Instrumentation

1.

The TS or other license conditions that will be violated.

LCO 3.4.4, Condition C, which requires the plant to be in MODE 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, and LCO 3.4.5, Condition C, which requires the plant to be in MODE 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

2.

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

On August 16, 2008, at approximately 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br />, EGC operations personnel attempted to pump the Unit 3 drywell floor drain sump utilizing Dresden Operating Procedure (DOP) 2000-24, "Drywell Sump Operation." Successful completion of DOP 2000-24 is used to partially satisfy TS Surveillance Requirement (SR) 3.4.4. 1, "Verify RCS unidentified and total LEAKAGE and unidentified LEAKAGE increase are within limits." The pumps started as expected, however, the integrator indicated no flow. During a second attempt to operate the pumps, EGC operations personnel observed the position indicators for the two containment isolation valves, which indicated that the valves were in their proper position. EGC maintenance personnel also inspected the pump breakers and measured pump motor current, with no abnormalities identified. The drywell floor drain sump pumps had been successfully pumped previously at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />, and every four hours prior.

Troubleshooting was performed to identify the possible malfunction. Based on the troubleshooting, it appeared that the 3-2001-105 containment isolation valve failed closed.

Since the drywell floor drain sump could not be pumped, the plant was not able to satisfactorily complete the requirements to satisfy SR 3.4.4.1. Therefore, the TS LCO 3.4.4 for unidentified leakage could not be verified to be within limits. The completion time for the associated action is 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to reduce LEAKAGE within limits.

The subsequent action is to place the plant in MODE 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

Due to the isolation valve being a part of primary containment, the valve cannot be repaired during plant operations. EGC requested an NOED to allow approval of an emergency TS change within 7 days. The TS change will allow the use of the drywell equipment drain sump system and its flow instrumentation to be temporarily utilized to monitor unidentified drywell leakage. The floor drain sump will be allowed to overflow into the equipment drain sump. Therefore, drywell leakage, both identified and unidentified, will be measured by the equipment drain sump system. All leakage in the drywell sumps will be conservatively treated as unidentified leakage. This action of allowing leakage into the drywell floor drain sump system to overflow into the drywell equipment drain sump system is similar to a configuration used successfully in the past on DNPS, Unit 2 and can be completed within the time frame being Page 2

requested. In July 2007, the DNPS, Unit 2 drywell equipment drain sump system failed to pump. Prior to the system being successfully returned to service, the floor drain sump system was effectively utilized to monitor the total drywell leakage in a similar manner as described above.

3.

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

Due to the isolation valve being a part of primary containment, the valve cannot be repaired during plant operations. EGC requested an NOED to allow the NRC time to process an emergency TS change within 7 days. In conjunction with the NOED request, actions, were taken to allow the floor drain sump to overflow to the equipment drain sump. While this configuration is being employed, all drywell leakage will be considered unidentified leakage. A drywell entry was made to re-baseline drywell leakage in order to allow the equipment drain sump integrator to be utilized to determine the unidentified and identified drywell leakage. As described previously, the action of allowing leakage into the drywell floor drain sump system to overflow into the drywell equipment drain sump system has been used successfully in the past and can be completed within the time frame being requested. The equipment drain sump is adjacent to the floor drain sump and the two sumps have equivalent instrumentation. The flow instrumentation for both the equipment and floor drain sumps is tested by the same procedures and at the same frequency. Therefore, there is no reduction in the ability to monitor total drywell leakage.

4.

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

A risk assessment was performed and risk was found to be within DNPS's normal work control limits.

The risk assessment was broken down into two periods. The first period was prior to the alternate (equivalent) Leak Detection (LD) System being in place and the second period being the period after the equivalent system being in place.

After the alternate LD System is in place, the assumption is that there is no increase in risk as the ability to detect increases in drywell leakage is not impacted.

During the initial period prior to establishing the alternate LD system, leak detection was degraded. The PRA assumption used is that LOCA frequencies (small, medium and large LOCAs) would increase by a factor of 10. This is more conservative and does not credit Containment Atmospheric Monitoring (CAM), increasing drywell temperatures or alternate sump pump monitoring as precursors to a LOCA.

The incremental increase for Core Damage Probability (ICDP) for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is 5E-09.

The incremental increase for Large Early Release Probability (ILERP) for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is 7E-10. These probabilities are approximately two orders of magnitude below the NRC Risk Thresholds of 5E-07 and 5E-08 respectively.

Note that the ICDP reaches 5E-07 in approximately 36 days. The LERP reaches 5E-08 in approximately 22 days.

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Based on the risk increase in this period, the risk is within DNPS's normal work control limits and is equivalent to a yellow condition. Dominant risk contributors are loss of High Pressure Coolant Injection (HPCI) and the Operator Action to initiate the Automatic Depressurization System (ADS). HPCI was a protected pathway during this time and Operating crews are being briefed on the importance to ADS during a LOCA scenario.

There are no PRA common cause factors associated with other equipment.

External Events were reviewed (Fire, Seismic and River flooding) and no increase in risk associated with these events was found.

Weather conditions are acceptable and will not affect risk.

5.

The justification for the duration of the noncompliance.

Seven days was requested to allow the review and approval of a temporary emergency TS change and to obtain new baseline drywell leak rate data.

6.

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

Unit 3 reduced power to support drywell entry. There is no safety-related equipment out of service that would adversely affect the current plant condition.

7.

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

The proposed actions will not affect off-site or on-site power sources.

8.

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

While this configuration is being employed, all drywell leakage will be considered unidentified leakage and will therefore be conservative. Drywell entry was made to re-baseline drywell leakage in order to allow the equipment drain sump integrator to be utilized to determine the unidentified and identified drywell leakage. For DNPS, Unit 2, a similar action of allowing leakage into the drywell equipment drain sump system to overflow into the drywell floor drain sump system has been used successfully in the past and can be completed within the time frame being requested.

The equipment drain sump is adjacent to the floor drain sump and the instrumentation is tested by the same procedures and at the same,frequency as the floor drain instrumentation. Therefore there is no reduction in the ability to monitor total drywell leakage.

9.

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

There is no change in the types or increase in the amounts of any effluent that may be released offsite, since the proposed actions do not affect the generation of any Page 4

radioactive effluent nor do they affect any of the permitted release paths. There is no increase in individual or cumulative occupational radiation exposure. The actions proposed in this request for Enforcement Discretion will not affect plant radiation levels, and, therefore, do not affect dose rates and occupational exposure.

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

The DNPS Plant Operations Review Committee (PORC) met on August 17, 2008.

The PORC committee met all PORC requirements. The NOED was reviewed by the committee, and was unanimously approved by the committee for submission to the NRC.

11. The request must specifically address which of the NOED criteria for appropriate plant conditions specified in Section B of "NRC Inspection Manual Part 9900: Technical Guidance" is satisfied and how it is satisfied.

EGC has evaluated the requested Enforcement Discretion against the criteria specified in the Inspection Manual. It has been determined that the requested actions meet the NOED criteria for an operating plant. This determination is based on the avoidance of an undesirable transient caused by the shutdown of the reactor as a result of forcing compliance with the TS and, thus, minimizes potential safety consequences and operational risks associated with a plant shutdown.

The NOED written request will be submitted within two working days (i.e., by August 19, 2008).

12. Unless otherwise agreed as discussed in Section B of "NRC Inspection Manual Part 9900: Technical Guidance", a commitment is required from the licensee that the written NOED request will be submitted within 2 working days and the follow-up amendment will be submitted within 4 working days of verbally granting the NOED.

Due to the duration of the request for Enforcement Discretion, a temporary TS change will be required. EGC agreed to submit a License Amendment Request by close of business on August 18, 2008, and justify the emergency request. 10 CFR 50.91 provides additional guidance on emergency TS changes. The need for the license amendment was discussed in the call with the NRC on August 17, 2008.

Subsequently, the emergency License Amendment Request was submitted to the NRC in a letter dated August 19, 2008.

13. In addition to items 1-12 above, for a severe-weather NOED request, the licensee must provide the severe weather information.

The requested NOED does not involve severe weather.

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