RS-08-018, Additional Information Supporting Request for Amendment to Technical Specification 5.5.16, Containment Leakage Rate Testing Program.
| ML080570644 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 02/26/2008 |
| From: | Simpson P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2010-0209, RS-08-018 | |
| Download: ML080570644 (9) | |
Text
Exelon Exelon Generation Nuclear www.exeloncorp .co m 4300 Wirnfield Road Warrenville, IL 60555 RS-08-018 February 26, 2008 U . S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos . NPF-37 and NPF-66 NRC Docket N os. STN 50-454 and STN 50-455
Subject:
Additional Information Supporting Request for Amendment to Technical Specification 5 .5.16, "Containment Leakage Rate Testing Program" References : 1 . Letter from D. M. Benyak (Exelon Generation Company, LLC) to U .S. NRC, "Request for Amendment to Technical Specification 5 .5.16, 'Containment Leakage Rate Testing Program,"' dated April 4, 2007
- 2. Letter from P. R. Simpson (Exelon Generation Company, LLC) to U.S. NRC, "Response to Request for Additional Information Regarding Request for Amendment to Technical Specification 5.5.16, 'Containment Leakage Rate Testing Program,"' dated October 10, 2007
- 3. Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S. NRC, "Additional Information Supporting Request for Amendment to Technical Specification 5.5 .16, 'Containment Leakage Rate Testing Program,"' dated January 31, 2008 In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Appendix A, Technical Specifications (TS), of Facility Operating License Nos . NPF-72, NPF-77, NPF-37, and NPF-66 for Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, respectively . The proposed change revises TS 5.5.16, "Containment Leakage Rate Testing Program," to reflect a one-time five-year deferral of the containment Type A integrated leak rate test from once in 10 years to once in 15 years.
February 26, 2008 U . S . Nuclear Regulatory Commission Page 2 Additional information supporting this request was submitted to the NRC in Reference 2. In the Reference 2 submittal, EGC provided references to inservice inspection summary reports, which were previously submitted to the NRC, that provide information related to containment inservice inspections (CISIs) and historic highlights . In recent discussions with the NRC, the NRC requested that EGC provide a summary that documents significant indications noted during the CISIs and actions taken to disposition the indications. In response to this request, EGC is providing the attached information for Braidwood Station. Similar information was previously submitted to the NRC for Byron Station in Reference 3.
There are no regulatory commitments contained in this letter. If you have any questions concerning this letter, please contact Mr. Kenneth M. Nicely at (630) 657-2803 .
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 26th day of February 2008.
Respectfully, Patrick R. Simpson Manager - Licensing
Attachment:
Summary of Braidwood Station Containment Inspections
ATTACHMENT Summary of Braidwood Station Containment Inspections Overview Significant indications noted during the Containment Inservice Inspections (CISIs) performed at Braidwood Station, Units 1 and 2, are summarized in Tables 1 and 2 below. The scope of this information pertains to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Subsection IWL, examinations associated with the Braidwood Station ASME Class CC Concrete Containment Structures and Post Tensioning Systems (i .e., tendons) . Specifically, summary information from the previous two ASME Section XI, Subsection IWL, surveillance activities (i.e., examinations performed in 2001 and 2006) is provided.
In addition, augmented examinations of selected concrete locations and post tensioning system grease caps are performed on an annual basis. A summary of the augmented examinations is also provided .
Significant indications identified during ASME Section XI, Subsection IWE, examinations associated with the Braidwood Station metallic liner were previously submitted to the NRC in the referenced letter (i .e ., response to NRC Request 7). These indications were related to moisture barrier degradation. No other significant indications were identified during the [WE examinations .
ASME Section XI Concrete Examinations Concrete examinations performed in 2001 and 2006 in accordance with ASME Section XI, Subsection IWL, revealed no conditions that could potentially challenge the structural integrity of the containment structures at Braidwood Station. However, indications were identified during the examinations that required evaluation and, in some instances, repair . Annual augmented examinations have also been established for some indications. Table 1 provides specific examples of important findings, actions to disposition the findings, and the date of the corresponding inservice inspection summary report .
The Summary Report Date column lists "N/A" for some of the findings. These findings were deemed important; however, reporting in the inservice inspection summary report was not required .
Table 1 ASME Section XI IWE Concrete Examination Indications Year Summary Unit Identified Description of Finding Disposition Report Date 1 2001 Evidence of moisture was identified Indication was examined Note 1 inside the Main Steam Isolation Valve again during 2002. No (MSIV) room at the point where the change in condition was floor meets the wall . Discolored identified .
concrete was identified .
1 2001 Construction wood was discovered Wood was removed and a Note 1 embedded in the concrete wall . cosmetic repair was completed .
Page 1
ATTACHMENT Summary of Braidwood Station Containment Inspections Table 1 ASIVIE Section XI IWL Concrete Examination Indications Year Summary Unit Identified Description of Finding Disposition Report Date 1 2001 A degraded construction joint was Due to the evidence of Note 1 identified below grade level. moisture, a cosmetic repair Dry/white minerals existed within the was completed . No joint and there was evidence of degraded reinforcing steel moisture in the past. was identified during the repair.
1 2001 A small area of honeycomb existed in Due to the void existing Note 1 the vicinity of a horizontal tendon near the tendon anchorage bearing plate . The edge of the bearing plate and the bearing plate was exposed, and presence of moisture, moisture was seeping from the void. repairs were completed .
No degraded reinforcing steel was identified during the repair .
1 2001 Approximately 80% of the The containment dome 01/10/2002 containment dome surface (i.e., surface was re-coated . 08/12/2002 exposed to elements) was degraded.
1 2006 Degradation was identified in the form The indication was N/A of voids, cracks, minerals, and evaluated ; the indication evidence of moisture intrusion in the does not affect the tendon tunnel ceiling near vertical structural integrity of the tendon anchorage locations V-41 and containment . Cosmetic V-79. The source of moisture was repairs are scheduled to be ground water. completed by July 1, 2008.
1 2006 Grease leakage was identified The indication is acceptable 02/22/2008 through the containment wall exterior based on the small quantity near a previously placed patch that of grease loss. The was installed to support the steam indication is being generator replacement project . The monitored on an annual source of leakage is sheathing filler basis during the summer through a crack. months, when the sheathing filler viscosity results in the worst-case condition for leakage .
1 2007 Grease leakage was identified The indication is acceptable 02/22/2008 through the containment wall exterior based on the small quantity at a horizontal construction joint. of grease loss. The This indication was identified during indication is being general walkdowns, not during a monitored on an annual scheduled ASME Section XI, basis during the summer months, when the Subsection IWL, surveillance activity.
sheathing filler viscosity results in the worst-case condition for leakage .
2 2001 Construction wood was discovered Wood was removed and a N/A embedded in the concrete wall. cosmetic repair was completed.
Page 2
ATTACHMENT Summary of Braidwood Station Containment Inspections Table 1 ASME Section XI IWL Concrete Examination Indications Year Summary Unit Identified Description of Finding Disposition Report Date 2 2001 Construction-related voids were Due to exposed reinforcing N/A identified in the E/ED and E/FE steel, cosmetic repairs were buttresses, with the end of reinforcing completed. No degraded steel members exposed . reinforcing steel was identified during the repairs.
2 2006 Degradation was identified in the form The indication was N/A of wet stalactites, discolored mineral evaluated ; the indication deposits, and cracking near a does not affect the previously placed patch in the tendon structural integrity of the tunnel ceiling near the anchorage for containment. Cosmetic tendon V-345 . The source of repairs are scheduled to be moisture was ground water. completed by July 1, 2008.
2 2006 Degradation was identified in the form The indication was N/A of discolored mineral deposits, evaluated ; the indication cracks, and evidence of moisture near does not affect the a previously placed patch in the structural integrity of the tendon tunnel ceiling near the containment . Cosmetic anchorage for tendon V-348 . The repairs are scheduled to be indication was adjacent to an completed by July 1, 2008.
embedded plate . The source of moisture was ground water.
2 2006 Degradation was identified in a The indication was N/A previously placed patch in the exterior evaluated ; the indication of the containment surface (i .e., does not affect the outdoors) . The degradation was structural integrity of the caused by moisture entering containment . Cosmetic underneath the patching material . repairs are scheduled to be The freeze/thaw cycles caused completed by July 1, 2008.
materials to loosen and fall away. No evidence of exposed reinforcing steel was observed .
2 2006 Grease leakage was identified The indication is acceptable 01/29/2007 through the containment wall exterior based on the small quantity at a construction joint. of grease loss. The indication is being monitored on an annual basis during the summer months, when the sheathing filler viscosity results in the worst-case condition for leakage.
Note 1 : The Summary Report dated January 29, 2002, identified 29 indications that required additional actions (i .e., cosmetic repair or additional examinations) to ensure the indications did not create conditions where structural degradation may occur. This indication is one of the 29 reported indications .
Page 3
ATTACHMENT Summary of Braidwood Station Containment Inspections ASME Section XI Post Tensioninq Indications During the ASME Section XI, Subsection IWL, Post Tensioning (i.e ., tendon) examinations performed in 2001 and 2006, no conditions were identified that could potentially challenge the structural integrity of the Braidwood Station containment structures. Identified findings were evaluated and dispositioned as acceptable. Table 2 provides specific examples of important findings, actions to disposition the findings, and the date of the corresponding inservice inspection summary report .
The Summary Report Date column lists "N/A" for some of the findings . These findings were deemed important; however, reporting in the inservice inspection summary report was not required .
Table 2
_ ASME Section XI IWL Post Ten sionin g (Tendon) Indica tions Year Summary Unit Identified Description of Fin ding Disposition Report Date 1 2001 Water was discovered in tendon A sheathing filler sample 01/10/2002 D-1-37. was obtained and analyzed 08/12/2002 per ASME Section XI . No evidence of active corrosion was identified . Sheathing filler grease was replaced in the tendon end .
1 2001 A missing wire/button head was An evaluation was 01/10/2002 identified on horizontal tendon performed; dispositioned as 08/12/2002 H-34-AC . The cause was acceptable. No evidence of construction-related . The wire was active corrosion was documented as a split button head identified.
during construction and was not considered as an effective wire during construction .
1 2006 Water was discovered in several Sheathing filler samples 07/28/2006 tendons. were obtained and analyzed per ASME Section X1 . No evidence of active corrosion was identified . Sheathing filler grease was replaced in the tendon ends.
ATTACHMENT Summary of Braidwood Station Containment Inspections Table 2 ASME Section XI IWL Post Tensioning (Tendon) Indications Year Summary Unit Identified Description of Finding Disposition Report Date 1 2006 During the as-found VT-1 examination The two wires were N/A of the field end of tendon H-67-CB, documented as "chewed" two ineffective wires were observed wires during construction that had not been identified during the and were rejected during last inspection (i.e., original construction . The construction) . evaluation of the condition concluded the probable cause of the indication was the damaged wires receded below the face of the anchor head between the time of construction and the 2006 surveillance .
1 2006 Vertical tendon V-133 was de- An evaluation was N/A tensioned for the purpose of wire performed; dispositioned as removal and testing . During re- acceptable. Physical tests tensioning, an additional wire was on wire that was removed discovered to be missing . The wire met all acceptance criteria .
receded into the anchor head during re-tensioning .
2 2001 Saturated moisture and water was Sheathing filler samples 01/10/2002 discovered in several tendons . were obtained and 08/12/2002 analyzed per ASME Section XI. No evidence of active corrosion was identified . Sheathing filler grease was replaced in the tendon ends for all but four tendons. For the four tendons with a history of free water accumulation, sheathing filler grease was replaced in the entire tendon ; wire was removed and subjected to examination and physical testing was performed. In addition, a continuity test was performed on all wires of one tendon .
2 2001 During the de-tensioning process, an The tendon was subjected 01/10/2002 additional button-head was identified to physical testing . The 08/12/2002 as missing . The cause was wire was removed for determined to be a button head that examination and testing . A was identified as being undersized continuity test was during construction that had slipped performed on the tendon into the anchorage . wires. All acceptance criteria were met .
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ATTACHMENT Summary of Braidwood Station Containment Inspections Table 2 ASME Section XI IWL Post Tensioning (Tendon) Indications Year Summary Unit Identified Description of Finding Disposition Report Date 2 2006 Water was discovered in several Sheathing filler samples 01/29/2007 tendons. were obtained and analyzed per ASME Section XI. No evidence of active corrosion was identified . Sheathing filler grease was replaced in the tendon ends.
2 2006 For the shop end of horizontal tendon The exact cause was not N/A H-26-DF, two protruding wires were determined . However, the identified during original construction . likely cause was attributed During the 2006 surveillance, three to this wire extending out protruding wires were identified. from the anchorage over time due to "bird-nesting" (i .e., twisting) during construction .
2 2006 For the field end of vertical tendon This wire was documented N/A V-225, no missing or unseated wires as a "chewed" wire during were identified during original construction and was construction . During the 2006 rejected during surveillance, one missing wire was construction . The identified. evaluation of the condition concluded the probable cause of the indication was the damaged wires receded below the face of the anchor head between the time of construction and the 2006 surveillance .
Augmented Inspections and Tests Annual examinations of all tendon grease caps, at locations below grade and on the dome, are performed at Braidwood Station due to a history of free water at specific locations . During the examinations, the grease caps are inspected for leakage, deformation, and evidence of moisture . No conditions that challenge the structural integrity of the grease caps have been identified .
During every post tensioning surveillance (i .e., five year frequency), specific tendons that have exhibited free water are selected for examination in addition to the population required by ASME Section XI, Subsection IWL . Findings identified during these examinations are evaluated and dispositioned in accordance with ASME Section XI, Subsection IWL .
With regard to augmented concrete examinations, the augmented examinations are discussed in Table 1 . Annual examination of selected areas are performed to monitor the conditions to ensure structural integrity is not challenged .
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ATTACHMENT Summary of Braidwood Station Containment Inspections Reference Letter from P. R. Simpson (Exelon Generation Company, LLC) to NRC, "Response to Request for Additional Information Regarding Request for Amendment to Technical Specification 5.5 .16,
'Containment Leakage Rate Testing Program,"' dated October 10, 2007