ML082341115
| ML082341115 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 08/21/2008 |
| From: | Pederson C Division Reactor Projects III |
| To: | Pardee C Exelon Generation Co |
| References | |
| NOED 08-3-002 | |
| Download: ML082341115 (6) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION REGION III 2443 WARRENVILLE ROAD, SUITE 210 LISLE, IL 60532-4352 August 21, 2008 Mr. Charles G. Pardee Chief Nuclear Officer and Senior Vice President Exelon Generation Company, LLC 4300 Winfield Road Warrenville IL 60555
SUBJECT:
NOTICE OF ENFORCEMENT DISCRETION FOR EXELON GENERATION COMPANY LLC REGARDING DRESDEN NUCLEAR POWER STATION, UNIT 3 (NOED 08-3-002)
Dear Mr. Pardee:
By letter dated August 19, 2008, you requested that the U.S. Nuclear Regulatory Commission (NRC) exercise discretion to not enforce compliance with the actions required in Technical Specification (TS) 3.4.4, ARCS Operational leakage,@ and TS 3.4.5, ARCS Leakage Detection Instrumentation,@ for Dresden Nuclear Power Station (DNPS), Unit 3. Your letter documented information previously discussed with the NRC in a telephone conference on August 17, 2008, at 10:30 a.m. (All times discussed in this letter refer to Central Daylight-Savings Time). You stated that on August 16, 2008, Dresden Operations discovered that the Unit 3 drywell floor drain sump could not be pumped to measure leakage and satisfy Surveillance Requirement 3.4.4.1 for TS 3.4.4. Subsequently, your troubleshooting identified that the likely cause was that drywell floor drain sump pump discharge valve 3-2001-105 had failed closed. You stated that valve 3-2001-105 is also a containment isolation valve and repairs to the valve could not be made with the unit online. Because of this condition, the unidentified reactor coolant system (RCS) operational leakage could not be measured and, therefore, the Limiting Condition for Operation (LCO) of TS 3.4.4 could not be met. In addition, TS 3.4.5 requires the drywell floor drain sump monitoring system be operable with the unit in Mode 1 (Power Operation) and this LCO also could not be met. When the LCO cannot be met, both TS 3.4.4 Action C and TS 3.4.5 Action C require the unit to be placed in Mode 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This would have required the shutdown of Unit 3.
You requested that a Notice of Enforcement Discretion (NOED) be granted pursuant to the NRC=s policy regarding exercise of discretion for an operating facility, set out in Section VII.C of the NRC Enforcement Policy, to extend the TS completion time by 7 days in order 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. Reconfiguration involved filling the drywell floor drain sump and uncovering a portion of the drywell equipment drain sump, such that the floor drain sump overflowed into the drywell equipment drain sump.
The drywell equipment drain sump will be used to measure all leakage and all leakage will be treated as unidentified leakage. In addition, the extension would allow Exelon to submit and
the NRC to review an emergency license amendment request to support this alternative method of verifying that unidentified leakage is within limits. This letter documents our telephone conversation on August 17, 2008, when we orally issued this NOED at 12:00 p.m. We understand that the reconfiguration of the drywell sumps was completed on August 17, 2008, and the emergency license amendment was submitted on August 18, 2008. This NOED is considered to be effective until 12:00 p.m. on August 24, 2008, at which time, if the emergency license amendment is not approved, Dresden Unit 3 would be required to re-enter the action statements of TS 3.4.4 and 3.4.5 and be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The principal NRC staff members who participated in that telephone conference included:
Cynthia Pederson, Director, Division of Reactor Projects (DRP), RIII; Timothy McGinty, Deputy Director, Division of Operating Reactor Licensing (DORL), Office of Nuclear Reactor Regulation (NRR); Mark Ring, Chief, Reactor Projects Branch 1, DRP, RIII; Daneira Melendez, Resident Inspector, Dresden; Christopher Gratton, Senior Project Manager, DORL, NRR; Donald Harrison, Chief, Balance of Plant Branch, Division of Safety Systems, NRR; Gerald Waig, Technical Specifications Branch, Division of Inspection and Regional Support, NRR; Laura Kozak, Senior Risk Analyst, Division of Reactor Safety, RIII; and See Meng Wong, PRA Operational Support and Maintenance Branch, Division of Risk Assessment, NRR.
Your staff requested this NOED after consideration of the safety significance and potential consequences of such an action. Your staff performed a risk assessment of operating Unit 3 during the period of the NOED and found risk to be within DNPSs normal work control limits.
The risk assessment was performed for both the period before the alternate leak detection system (reconfiguration of the two sumps) was in place and the period after the alternate leak detection system was in place. The results of the risk assessment for both periods of operation over seven days with the normal drywell floor drain sump system not available showed that there would be no net increase in radiological risk to the public.
Your staff stated that after the alternate leak detection system is in place, the ability to detect increases in drywell leakage is not impacted and, therefore, there is no increase in risk. Your staff stated that during the period before the alternate leak detection system is in place (estimated to be completed within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />), leak detection is degraded. Your probabilistic risk assessment (PRA) assumption was that the Loss of Coolant Accident (LOCA) frequencies would increase by a factor of 10. You noted that this was a conservative assumption because other leak detection capabilities, such as increasing drywell temperatures and Containment Atmospheric Monitoring (CAM), were not credited. Your staff stated that the incremental increase in Core Damage Probability for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is 5E-09 and the incremental increase in Large Early Release Probability 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. Your staff concluded that based on the risk increase during this period, the risk is within DNPSs normal work control limits. Your letter also stated that loss of High Pressure Coolant Injection (HPCI) and operator action to initiate the Automatic Depressurization System (ADS) were the dominant contributors to risk. As a result, HPCI was a protected pathway during the period and operating crews were briefed on the importance of ADS for a LOCA scenario. A Region III Senior Risk Analyst reviewed this risk analysis and determined the values to be appropriate.
The NRC reviewed your written request for enforcement discretion dated August 19, 2008, and verified consistency between your oral and written requests. The NRC=s basis for this discretion
considered the information discussed above including: (1) the reconfiguration of the drywell floor drain and drywell equipment drain sumps to provide an alternate method of determining reactor coolant system (RCS) operational leakage, (2) the treatment of all RCS leakage as unidentified leakage, (3) the submittal of an emergency license amendment to address the condition, and (4) the qualitative and quantitative risk evaluation of the condition which determined that the calculated risk increases were consistent with normal work control levels and, therefore, would not increase the radiological risk to the public.
Based on the above considerations, the NRC staff concluded that Criterion B.2.1.1.a and the applicable criteria in Section D.4 to NRC Manual Chapter 9900, ATechnical Guidance, Operations B Notice of Enforcement Discretion,@ were met. Criterion B.2.1.1.a states that for an operating plant, the NOED is intended to avoid unnecessary transients as a result of compliance with the license condition and, thus, minimize potential safety consequences and operational risks.
On the basis of the staff=s evaluation of your request, we have concluded that granting this NOED was consistent with the Enforcement Policy and staff guidance, and had no adverse impact on public health and safety or the environment. Therefore, we exercise discretion to not enforce compliance with TS 3.4.4 Required Action C.1 and C.2 and TS 3.4.5 Required Action C.1 and C.2 for entry into Mode 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> from 12:00 p.m. on August 17, 2008, until 12:00 p.m. on August 24, 2008. As discussed earlier in this letter, an emergency license amendment request is required and has been submitted for this issue.
As stated in the Enforcement Policy, action will be taken, to the extent that violations were involved, for the root cause that led to the noncompliance for which this NOED was necessary.
Sincerely,
/RA/
Cynthia Pederson, Director Division of Reactor Projects Docket No. 50-249 License No. DPR-25 DISTRIBUTION:
See next page
Letter to C. Pardee from C. Pederson dated August 21, 2008
SUBJECT:
NOTICE OF ENFORCEMENT DISCRETION FOR EXELON GENERATION COMPANY LLC REGARDING DRESDEN NUCLEAR POWER STATION, UNIT 3 (NOED 08-3-002) cc:
Site Vice President - Dresden Nuclear Power Station Plant Manager - Dresden Nuclear Power Station Regulatory Assurance Manager - Dresden Nuclear Power Station Chief Operating Officer and Senior Vice President Senior Vice President - Midwest Operations Senior Vice President - Operations Support Vice President - Licensing and Regulatory Affairs Director - Licensing and Regulatory Affairs Manager Licensing - Clinton, Dresden, and Quad Cities Associate General Counsel Document Control Desk - Licensing Assistant Attorney General J. Klinger, State Liaison Officer, Illinois Emergency Management Agency Chairman, Illinois Commerce Commission
discretion considered the information discussed above including: (1) the reconfiguration of the drywell floor drain and drywell equipment drain sumps to provide an alternate method of determining reactor coolant system (RCS) operational leakage, (2) the treatment of all RCS leakage as unidentified leakage, (3) the submittal of an emergency license amendment to address the condition, and (4) the qualitative and quantitative risk evaluation of the condition which determined that the calculated risk increases were consistent with normal work control levels and, therefore, would not increase the radiological risk to the public.
Based on the above considerations, the NRC staff concluded that Criterion B.2.1.1.a and the applicable criteria in Section D.4 to NRC Manual Chapter 9900, ATechnical Guidance, Operations B Notice of Enforcement Discretion,@ were met. Criterion B.2.1.1.a states that for an operating plant, the NOED is intended to avoid unnecessary transients as a result of compliance with the license condition and, thus, minimize potential safety consequences and operational risks.
On the basis of the staff=s evaluation of your request, we have concluded that granting this NOED was consistent with the Enforcement Policy and staff guidance, and had no adverse impact on public health and safety or the environment. Therefore, we exercise discretion to not enforce compliance with TS 3.4.4 Required Action C.1 and C.2 and TS 3.4.5 Required Action C.1 and C.2 for entry into Mode 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> from 12:00 p.m. on August 17, 2008, until 12:00 p.m. on August 24, 2008. As discussed earlier in this letter, an emergency license amendment request is required and has been submitted for this issue.
As stated in the Enforcement Policy, action will be taken, to the extent that violations were involved, for the root cause that led to the noncompliance for which this NOED was necessary.
Sincerely,
/RA/
Cynthia Pederson, Director Division of Reactor Projects Docket No. 50-249 License No. DPR-25 DISTRIBUTION:
See next page DOCUMENT NAME: G:\\Dres\\Dres NOED U3 Drywell floor drain (final).doc Publicly Available Non-Publicly Available Sensitive Non-Sensitive To receive a copy of this document, indicate in the concurrence box "C" = Copy without attach/encl "E" = Copy with attach/encl "N" = No copy FFICE RIII RIII NAME MRing:cms SBurgess for LKozak Per telcon CGratton to MRing TMcGinty KOBrien CPederson DATE 8/20/08 8/21/08 8/21/08 8/21/08 8/21/08 OFFICIAL RECORD COPY
Letter to C. Pardee from C. Pederson dated August 21, 2008
SUBJECT:
NOTICE OF ENFORCEMENT DISCRETION FOR EXELON GENERATION COMPANY LLC REGARDING DRESDEN NUCLEAR POWER STATION, UNIT 3 (NOED 08-3-002)
DISTRIBUTION:
NOED OEWEB Tamara Bloomer Russell Gibbs Christopher Gratton Tim McGinty RidsNrrDirsIrib Resource Mark Satorius Kenneth Obrien Jared Heck Carole Ariano Linda Linn Cynthia Pederson DRPIII DRSIII Patricia Buckley Tammy Tomczak RidsSecymailcenter Bruce Mallett, DEDR Cynthia Carpenter, OE Doug Starkey, OE Eric Leeds, NRR MaryAnn Ashley, NRR Frederick Brown, NRR James Caldwell, RIII Christopher Chandler, OGC Catherine Marco, OGC Rachel Romine, OGC Eliot Brenner, OPA Hubert Bell, OIG Guy Caputo, OI Daniel Holody, RI Carolyn Evans, RII William Jones, RIV Viktoria Mitlyng, RIII Prema Chandrathil, RIII Allan Barker, RIII James Lynch, RIII Patricia Lougheed, RIII Paul Pelke, RIII Magdalena Gryglak, RIII OEMAIL