ML12311A470
| ML12311A470 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 11/06/2012 |
| From: | Gallagher M Exelon Generation Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| Download: ML12311A470 (4) | |
Text
10 10 CFR 51 10 CFR54 November 6, 2012 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Units 1 and 2
."".,C"" Nos. NPF-39 and NPF-85
Subject:
Exelon Generation Company, LLC Review of the Safety Evaluation Report with Open Items related to the Limerick Generating Station License Renewal Application
Reference:
- 1. Letter from Brian E. Holian (NRC) to Michael P. Gallagher (Exelon), "Safety Evaluation Report with Open Items Related to the License Renewal of Limerick Generating Station, Units 1 and 2 (TAC Nos. ME6555, ME6556)", dated July 31, 2012
- 2. Michael P. Gallagher (Exelon), "Exelon Generation Company, LLC Review of the Safety Evaluation Report with Open Items related to the Limerick Generating Station License Renewal Application", dated October 12, 2012 In the Reference 1 letter, the U.S. Nuclear Regulatory Commission issued the Safety Evaluation Report with Open Items (SER) related to the LGS License Renewal Application and requested Exelon to review the SER and provide comments to the staff within 45 days of the date of that letter.
In the Reference 2 letter, Exelon provided additional comments on the SER regarding one of the two proposed license conditions. This letter supplements the Reference 2 letter by providing additional information and basis regarding Exelon comments on one of the two proposed license conditions.
The language that Exelon is commenting on is located on page 1-8 of the SER and states: "The second license condition requires future activities described in the UFSAR supplement to be completed prior to the period of extended operation. The applicant shall complete these activities no later than six months prior to the period of extended operation, and shall notify the NRC in writing when implementation of these activities is complete."
U.S. Nuclear Regulatory Commission November 6, 2012 Page 2 As stated in the reference 2 letter, Not allowing performing aging management activities in the last refueling outage prior to the PEO has additional undesirable consequences. As a result of this proposed License condition, 2.5 years of opportunity to perform outage related inspections is lost as well as the potential impacts on LGS Aging Management Programs implementation detailed in the following table:
LGS AMP NUREG 1801 (GALL Rev. 2) Basis NUREG 1800 (SRP Rev. 2) Basis LGS Impact from proposed License Condition B.2.1.22 One-Time Inspection GALL XI. M32 NUREG 1801: With respect to inspection timing, Specifically, inspections need to be completed early enough to ensure that the aging effects that may affect intended functions early in the period of extended operation are appropriately managed. Conversely, inspections need to be timed to allow the inspected components to attain sufficient age to ensure that the aging effects with long incubation periods (i.e., those that may affect intended functions near the end of the period of extended operation) are identified. Within these constraints, the applicant should schedule the inspection no earlier than 10 years prior to the period of extended operation and in such a way as to minimize the impact on plant operations. As a plant will have operated for at least 30 years before inspections under this program begin, sufficient time will have elapsed for any aging effects to be manifested.
NUREG 1800, Table 3.0-1 FSAR Supplement for Aging Management of Applicable Systems Implementation Schedule: Program should be implemented prior to period of extended operation Last Refueling Outage prior to PEO not available to perform outage related inspections.
Less time available to allow aging effects to develop prior to inspections.
Per GALL it is optimal to perform one-time inspections as late as possible to detect aging effects.
B.2.1.23 Selective Leaching GALL XI. M33 NUREG 1801: The visual inspection and hardness measurement or other mechanical examination techniques, such as destructive testing (when the opportunity arises), chipping, or scraping, is a one-time inspection conducted within the last 5 years prior to entering the period of extended operation. Because selective leaching is a slow acting corrosion process, this measurement is performed just prior to the period of extended operation. Follow-up of unacceptable inspection findings includes an evaluation using the corrective action program and a possible expansion of the inspection sample size and Location.
NUREG 1800, Table 3.0-1 FSAR Supplement for Aging Management of Applicable Systems Implementation Schedule: Program should be implemented prior to period of extended operation Last Refueling Outage prior to PEO not available to perform outage related inspections.
Less time available to allow aging effects to develop prior to inspections.
Per GALL it is optimal to perform one-time inspections as late as possible to detect aging effects.
U.S. Nuclear Regulatory Commission November 6, 2012 Page 3 B.2.1.24 ASME Code Class 1 Small-Bore Piping Program GALL XI. M35 NUREG 1801: The one time inspection should be completed within the six year period prior to the period of extended operation.
NUREG 1800, Table 3.0-1 FSAR Supplement for Aging Management of Applicable Systems Implementation Schedule: Program should be implemented prior to period of extended operation Last Refueling Outage prior to PEO not available to perform outage related inspections.
Less time available to allow aging effects to develop prior to inspections.
Per GALL it is optimal to perform one-time inspections as late as possible to detect aging effects.
Sample population increased from GALL Rev 1 to GALL Rev 2 so significantly more inspections must be performed during each outage (2 vs. 3 available outages).
A.2.1.40 Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements GALL XI.E3 NUREG 1801: The first tests for license renewal are to be completed prior to the period of extended operation with subsequent tests performed at least every 6 years thereafter.
NUREG 1800, Table 3.0-1 FSAR Supplement for Aging Management of Applicable Systems Implementation Schedule: First tests or first inspections for license renewal completed prior to the period of extended operation Last Refueling Outage prior to PEO not available to perform outage related inspections.
Less time available to allow aging effects to develop prior to inspections.
Electrical inspections are normally spread out over several refuel outages to coordinate with specific Electrical bus outages in order to minimize outage risk. Loss of one Refuel outage could result in multiple Electrical bus outages in a refuel outage which would increase Refuel Outage risk.
A.2.1.41 Metal Enclosed Bus GALL XI.E4 NUREG 1801: The first inspection using thermography or measuring connection resistance is completed prior to the period of extended operation and every 10 years thereafter provided visual inspection is not used to inspect bolted connections.
NUREG 1800, Table 3.0-1 FSAR Supplement for Aging Management of Applicable Systems Implementation Schedule: First inspection for license renewal completed prior to the period of extended operation Last Refueling Outage prior to PEO not available to perform outage related inspections.
Less time available to allow aging effects to develop prior to inspections.
Electrical inspections are normally spread out over several refuel outages to coordinate with specific Electrical bus outages in order to minimize Refuel Outage risk. Loss of one Refuel outage could result in multiple Electrical bus outages in a refuel outage which would increase Refuel Outage risk.
Other potential impacts:
Any inspection linked to a performance frequency of once every ISI interval could be an issue. For Unit 1, this means that anything scheduled for the last period of the third 10 year interval (outages in 2024 and 2026) would need to be scheduled to be performed in
U.S. Nuclear Regulatory Commission November 6, 2012 Page 4 the 2024 outage and potentially would not be able to meet the 6 month prior to PEO license condition requirement.
All outage related activities will have to be accomplished 2.5 years earlier and the average number of activities to be accomplished in the available Refuel outages will increase which in turn reduces Exelon's scheduling flexibility.
For the reasons cited above along with the reasons cited in the Reference 2 letter we request that the proposed License Condition be revised to remove the six month modifier as follows:
The Exelon Generation Company Updated Final Safety Analysis Report supplement submitted pursuant to 10 CFR 54.21 (d) describes certain future inspection activities to be completed prior to the period of extended operation. The licensee shall complete these activities prior to the period of extended operation and shall notify the NRC in writing when activities to be completed prior to the period of extended operation can be verified by NRC inspection.
There are no new or revised regulatory commitments contained in this letter.
If you have any questions, please contact Mr. AI Fulvio, Manager, Exelon License Renewal, at 610-765-5936.
Respectfully,
~f~
Michael P. Gallagher Vice President - License Renewal Projects Exelon Generation Company, LLC cc:
Regional Administrator - NRC Region I NRC Project Manager (Safety Review), NRR-DLR NRC Project Manager (Environmental Review), NRR-DLR NRC Project Manager, NRR-DORL Limerick Generating Station NRC Senior Resident Inspector, Limerick Generating Station R. R. Janati, Commonwealth of Pennsylvania