ML15289A099
| ML15289A099 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 10/15/2015 |
| From: | Siva Lingam Plant Licensing Branch IV |
| To: | Soenen P Pacific Gas & Electric Co |
| References | |
| MF6790 | |
| Download: ML15289A099 (3) | |
Text
NRR-PMDAPEm Resource From: Lingam, Siva Sent: Thursday, October 15, 2015 4:00 PM To: Soenen, Philippe R (PNS3@pge.com)
Cc: Markley, Michael; Alley, David; Cumblidge, Stephen; Schrader, Kenneth (KJSe@pge.com);
'mjrm@pge.com'
Subject:
Diablo Canyon, Unit 1 - Verbal Authorization for Relief Request FLIG-U1, Request for Extension of Third Inservice Inspection Interval for Performing Reactor Vessel stud Hole Ligament Examinations (CAC No. MF6790)
By telephone conference call on October 15, 2015, the U.S. Nuclear Regulatory Commission (NRC) staff provided verbal authorization to Pacific Gas and Electric Company (PG&E, the licensee) for the subject relief request (RR) based on the following explanation.
Participants:
NRC PG&E David Alley, Branch Chief (provided technical justification) Barry Allen, Vice President, Nuclear Services Michael T. Markley, Branch Chief (provided authorization) Adam Peck, Director of Engineering Stephen Cumblidge, Materials Engineer David Gonzalez, Supervisor of Inservice Inspection Siva P. Lingam, Project Manager Phillippe Soenen, Acting Manager of Regulatory Services VERBAL AUTHORIZATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR RELIEF REQUEST FLIG-U1 DIABLO CANYON POWER PLANT UNIT 1 PACIFIC GAS AND ELECTRIC COMPANY DOCKET NUMBER 50-275 (CAC NO. MF6790)
By a letter dated October 7, 2015 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML15280A505), as supplemented by a letter dated October 12, 2015 (ADAMS Accession No. ML15285A021), PG&E submitted Relief Request (RR) FLIG-U1 requesting to extend the third 10-year inservice inspection (ISI) interval to the end of the 20th refueling outage at Diablo Canyon Power Plant, Unit 1, which is currently scheduled to end in June of 2017. This would extend the 10-year ISI interval by approximately 13 months beyond that which is allowed by the American Society for Mechanical Engineers (ASME)Section XI Paragraph IWA-2430(d)(1).
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.55a(z)(2), the licensee proposes to extend the third 10-year ISI interval on the basis that performing the reactor vessel (RV) stud hole ligament inspections in the current refueling outage would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The licensee inspected the RV stud hole ligaments in February of 2014 using tooling designed to perform the inspections underwater. The inspection using this tooling was not able to achieve 100 percent of the volumetric coverage required by the ASME Section XI. ASME Code Case N-460 Alternative Examination Coverage for Class 1 and Class 2 Welds, which is listed in Regulatory Guide 1.147 Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1 as acceptable for use without conditions, allows for reduced 1
coverage of inspections due to interference by another component or part geometry. There are no provisions allowing reduced coverage in ASME Code N-460 for tooling.
Inspecting the RV stud holes in the third 10-year ISI interval would require the licensee to extend a RV head lift for the duration of the examinations, preparation for and installing blocking of the suspended load to allow safe personnel access underneath, performance of the accessible portion of the examinations (around the blocking), and lifting the RV head. The inspection and associated manipulation of the head is estimated to result in doses that exceed 600 mrem.
The licensee stated that the 2014 inspection achieved a coverage value of 98 percent. The NRC staff are still evaluating the effectiveness of this examination and the code coverage obtained. The NRC staff has determined that based on operational experience with RV stud holes and the coverage obtained that there is reasonable assurance that significant cracking has not occurred in the RV stud holes.
As described in the letter dated October 12, 2015, the inspections currently scheduled for the 20th refueling outage will be conducted as normal and credited to the fourth 10-year ISI interval. Thus, extending the third ten-year ISI interval will only affect the RV stud hole inspections.
A 600 mrem radiation dose for an examination is often not considered sufficient by the NRC staff to cancel or significantly delay a required inspection. The licensee has recently conducted an inspection with significant coverage and the licensee will either perform an RV stud hole inspection with 100 percent coverage or demonstrate that the inspection performed in February of 2014 met code requirements. The NRC staff have determined that this hardship is sufficient to permit the extension of the third 10-year ISI interval to the end of the 20th refueling outage.
Based on the above, the NRC staff has determined that the proposed extension of the third 10-year ISI interval to complete the inspections of the RV stud holes provides reasonable assurance of the leak tightness and structural integrity of the components. The NRC staff has concluded that examining the RV stud holes in the current refueling outage would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, effective October 15, 2015, the NRC authorizes the use of RR FLIG-U1 to extend the third 10-year ISI interval to the end of the 20th refueling outage at Diablo Canyon Power Plant, Unit 1, which is currently scheduled to end in June of 2017.
The NRC staff notes that all other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject request for relief remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
This verbal authorization does not preclude the NRC staff from asking additional clarification questions regarding subject relief request while preparing the subsequent written safety evaluation.
Siva P. Lingam U.S. Nuclear Regulatory Commission Project Manager (NRR/DORL/LPL4-1)
Cooper Nuclear Station Diablo Canyon Nuclear Power Plant Location: O8-D5; Mail Stop: O8-B3 Telephone: 301-415-1564; Fax: 301-415-1222 E-mail address: siva.lingam@nrc.gov 2
Hearing Identifier: NRR_PMDA Email Number: 2457 Mail Envelope Properties (Siva.Lingam@nrc.gov20151015155900)
Subject:
Diablo Canyon, Unit 1 - Verbal Authorization for Relief Request FLIG-U1, Request for Extension of Third Inservice Inspection Interval for Performing Reactor Vessel stud Hole Ligament Examinations (CAC No. MF6790)
Sent Date: 10/15/2015 3:59:31 PM Received Date: 10/15/2015 3:59:00 PM From: Lingam, Siva Created By: Siva.Lingam@nrc.gov Recipients:
"Markley, Michael" <Michael.Markley@nrc.gov>
Tracking Status: None "Alley, David" <David.Alley@nrc.gov>
Tracking Status: None "Cumblidge, Stephen" <Stephen.Cumblidge@nrc.gov>
Tracking Status: None "Schrader, Kenneth (KJSe@pge.com)" <KJSe@pge.com>
Tracking Status: None
"'mjrm@pge.com'" <mjrm@pge.com>
Tracking Status: None "Soenen, Philippe R (PNS3@pge.com)" <PNS3@pge.com>
Tracking Status: None Post Office:
Files Size Date & Time MESSAGE 6511 10/15/2015 3:59:00 PM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
Recipients Received:
NRR-PMDAPEm Resource From: Lingam, Siva Sent: Thursday, October 15, 2015 4:00 PM To: Soenen, Philippe R (PNS3@pge.com)
Cc: Markley, Michael; Alley, David; Cumblidge, Stephen; Schrader, Kenneth (KJSe@pge.com);
'mjrm@pge.com'
Subject:
Diablo Canyon, Unit 1 - Verbal Authorization for Relief Request FLIG-U1, Request for Extension of Third Inservice Inspection Interval for Performing Reactor Vessel stud Hole Ligament Examinations (CAC No. MF6790)
By telephone conference call on October 15, 2015, the U.S. Nuclear Regulatory Commission (NRC) staff provided verbal authorization to Pacific Gas and Electric Company (PG&E, the licensee) for the subject relief request (RR) based on the following explanation.
Participants:
NRC PG&E David Alley, Branch Chief (provided technical justification) Barry Allen, Vice President, Nuclear Services Michael T. Markley, Branch Chief (provided authorization) Adam Peck, Director of Engineering Stephen Cumblidge, Materials Engineer David Gonzalez, Supervisor of Inservice Inspection Siva P. Lingam, Project Manager Phillippe Soenen, Acting Manager of Regulatory Services VERBAL AUTHORIZATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR RELIEF REQUEST FLIG-U1 DIABLO CANYON POWER PLANT UNIT 1 PACIFIC GAS AND ELECTRIC COMPANY DOCKET NUMBER 50-275 (CAC NO. MF6790)
By a letter dated October 7, 2015 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML15280A505), as supplemented by a letter dated October 12, 2015 (ADAMS Accession No. ML15285A021), PG&E submitted Relief Request (RR) FLIG-U1 requesting to extend the third 10-year inservice inspection (ISI) interval to the end of the 20th refueling outage at Diablo Canyon Power Plant, Unit 1, which is currently scheduled to end in June of 2017. This would extend the 10-year ISI interval by approximately 13 months beyond that which is allowed by the American Society for Mechanical Engineers (ASME)Section XI Paragraph IWA-2430(d)(1).
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.55a(z)(2), the licensee proposes to extend the third 10-year ISI interval on the basis that performing the reactor vessel (RV) stud hole ligament inspections in the current refueling outage would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The licensee inspected the RV stud hole ligaments in February of 2014 using tooling designed to perform the inspections underwater. The inspection using this tooling was not able to achieve 100 percent of the volumetric coverage required by the ASME Section XI. ASME Code Case N-460 Alternative Examination Coverage for Class 1 and Class 2 Welds, which is listed in Regulatory Guide 1.147 Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1 as acceptable for use without conditions, allows for reduced 1
coverage of inspections due to interference by another component or part geometry. There are no provisions allowing reduced coverage in ASME Code N-460 for tooling.
Inspecting the RV stud holes in the third 10-year ISI interval would require the licensee to extend a RV head lift for the duration of the examinations, preparation for and installing blocking of the suspended load to allow safe personnel access underneath, performance of the accessible portion of the examinations (around the blocking), and lifting the RV head. The inspection and associated manipulation of the head is estimated to result in doses that exceed 600 mrem.
The licensee stated that the 2014 inspection achieved a coverage value of 98 percent. The NRC staff are still evaluating the effectiveness of this examination and the code coverage obtained. The NRC staff has determined that based on operational experience with RV stud holes and the coverage obtained that there is reasonable assurance that significant cracking has not occurred in the RV stud holes.
As described in the letter dated October 12, 2015, the inspections currently scheduled for the 20th refueling outage will be conducted as normal and credited to the fourth 10-year ISI interval. Thus, extending the third ten-year ISI interval will only affect the RV stud hole inspections.
A 600 mrem radiation dose for an examination is often not considered sufficient by the NRC staff to cancel or significantly delay a required inspection. The licensee has recently conducted an inspection with significant coverage and the licensee will either perform an RV stud hole inspection with 100 percent coverage or demonstrate that the inspection performed in February of 2014 met code requirements. The NRC staff have determined that this hardship is sufficient to permit the extension of the third 10-year ISI interval to the end of the 20th refueling outage.
Based on the above, the NRC staff has determined that the proposed extension of the third 10-year ISI interval to complete the inspections of the RV stud holes provides reasonable assurance of the leak tightness and structural integrity of the components. The NRC staff has concluded that examining the RV stud holes in the current refueling outage would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, effective October 15, 2015, the NRC authorizes the use of RR FLIG-U1 to extend the third 10-year ISI interval to the end of the 20th refueling outage at Diablo Canyon Power Plant, Unit 1, which is currently scheduled to end in June of 2017.
The NRC staff notes that all other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject request for relief remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
This verbal authorization does not preclude the NRC staff from asking additional clarification questions regarding subject relief request while preparing the subsequent written safety evaluation.
Siva P. Lingam U.S. Nuclear Regulatory Commission Project Manager (NRR/DORL/LPL4-1)
Cooper Nuclear Station Diablo Canyon Nuclear Power Plant Location: O8-D5; Mail Stop: O8-B3 Telephone: 301-415-1564; Fax: 301-415-1222 E-mail address: siva.lingam@nrc.gov 2
Hearing Identifier: NRR_PMDA Email Number: 2457 Mail Envelope Properties (Siva.Lingam@nrc.gov20151015155900)
Subject:
Diablo Canyon, Unit 1 - Verbal Authorization for Relief Request FLIG-U1, Request for Extension of Third Inservice Inspection Interval for Performing Reactor Vessel stud Hole Ligament Examinations (CAC No. MF6790)
Sent Date: 10/15/2015 3:59:31 PM Received Date: 10/15/2015 3:59:00 PM From: Lingam, Siva Created By: Siva.Lingam@nrc.gov Recipients:
"Markley, Michael" <Michael.Markley@nrc.gov>
Tracking Status: None "Alley, David" <David.Alley@nrc.gov>
Tracking Status: None "Cumblidge, Stephen" <Stephen.Cumblidge@nrc.gov>
Tracking Status: None "Schrader, Kenneth (KJSe@pge.com)" <KJSe@pge.com>
Tracking Status: None
"'mjrm@pge.com'" <mjrm@pge.com>
Tracking Status: None "Soenen, Philippe R (PNS3@pge.com)" <PNS3@pge.com>
Tracking Status: None Post Office:
Files Size Date & Time MESSAGE 6511 10/15/2015 3:59:00 PM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
Recipients Received: