ML103190021
| ML103190021 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/10/2010 |
| From: | - No Known Affiliation |
| To: | Division of License Renewal |
| References | |
| Download: ML103190021 (17) | |
Text
1 DiabloCanyonNPEm Resource From: Tan, Miranda [M1TF@pge.com]
Sent: Wednesday, November 10, 2010 5:50 PM To:Pick, Greg Cc: Grebel, Terence
Subject:
One time inspection - basis for sampling size and criteria Attachments:
DCL-10-134.pdf Greg, I am not sure if you received a copy of DCL-10-134. Page 4 of Enclosure 1 contains the basis for sampling size and criteria for One-Time Inspection program.
Best, Miranda Tan 805 781 9415
<<DCL-10-134.pdf>>
Hearing Identifier: DiabloCanyon_LicenseRenewal_NonPublic Email Number: 2181 Mail Envelope Properties (D065043718A59C4B99DDA1862BB067DE01BA2459)
Subject:
One time inspection - basis for sampling size and criteria Sent Date: 11/10/2010 5:49:42 PM Received Date: 11/10/2010 5:50:13 PM From: Tan, Miranda Created By: M1TF@pge.com Recipients: "Grebel, Terence" <TLG1@pge.com>
Tracking Status: None "Pick, Greg" <Greg.Pick@nrc.gov>
Tracking Status: None Post Office: exchange12.Utility.pge.com
Files Size Date & Time MESSAGE 237 11/10/2010 5:50:13 PM DCL-10-134.pdf 934363 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: Recipients Received:
PG&E Letter DCL-10-134 Page 1 of 5 PG&E Response to NRC Letter dated September 28, 2010, Summary of Telephone Conference Call Held on September 2, 2010, Concerning Responses to Requests for Additional Information (Set 1, 4, and 12) Related to the Diablo Canyon License Renewal Application RAI B2.1.13-2In its June 3, 2010, response to RAI B2.1.13-2, the applicant provided details of the basis for maintaining the 18-month inspection frequency for Fire Water System Program. However, the staff was unclear how the operating experience was applied as
part of the basis for the inspection frequency.
Discussion
- PG&E agreed to supplement its response to RAI B2.1.13-2 to clarify how operating experience was considered as part of the basis for the 18-month inspection frequency.
PG&E Supplemental Response to Question B2.1.13-2 PG&E letter DCL-10-057 dated June 3, 2010, provided a response to NRC Request for Additional Information (RAI) B2.1.13-2. The response to this RAI
revises/supplements the previously provided information on inspection frequency for
above grade fire water piping and below grade fire water piping.
Above grade Diablo Canyon Power Plant (DCPP) fire water piping is visually inspected for early indications of aging effects (such as material wastage, pitting, blistering, or
porosity) on an 18-month frequency. In addition, the firewater yard loop and
underground feeds are flushed semi-annually. The flowing water removes accumulated debris and/or sediment which can be indicative of internal pipe aging. The firewater
system is flow tested at least every three years in order to verify firewater system design
and National Fire Protection Association test requirements.
These testing frequencies are performed to satisfy DCPP equipment control guidelines (ECGs), which were relocated from the DCPP Technical Specifications. Per License
Amendments 74 and 75 for Units 1 and 2, respectively, NRC approved DCPP's request
to relocate the fire protection Technical Specifications and associated bases to the
ECGs. Therefore, DCPP's testing frequencies are in compliance with the licensing
basis previously approved by NRC. Plant procedures require that any degradation observed during inspection activities be entered into the corrective action program. As discussed in License Renewal
Application Section B2.1.13, several examples of degradation or corrosion of fire water
system including through wall leaks have occurred. These deficiencies were promptly PG&E Letter DCL-10-134 Page 2 of 5 corrected and did not affect the fire water system intended function. Corrective actions and preventive measures have been developed in response to plant-specific operating experience on firewater components to ensure their license renewal intended function is
maintained. DCPP corrective actions taken to resolve above grade firewater
piping/hydrant leakage operating experience include piping replacement with current
design specified materials; for example, ductile iron replaces cast iron pipe, polyvinyl
chloride pipe replaces asbestos cement pipe, and new fire hydrants installed when
degradation is identified. Planned buried pipe replacement will evaluate use of cathodic
protection based on pipe and soil excavation findings.
The plant specific visual inspection interval is determined by engineering evaluation of the fire protection piping to ensure that degradation is detected before the loss of intended function. As discussed above, the current DCPP above grade firewater piping
visual inspection frequency is 18 months. The ability of the fire water system to perform
its intended function is periodically reviewed as part of plant health review process. In
accordance with NUREG-1801, XI.M27, Fire Water System, the above grade visual
inspection frequency is evaluated in response to plant specific and industrial operating
experience to ensure this frequency is adequate for the fire water system above grade
piping to perform its intended function.
PG&E is currently revising the Buried and Underground Piping and Tanks Program as part of its response to the NRCs RAI Set 29, RAI B2.1.18-2 (Follow-up). This response
will also address below grade fire water piping inspections and frequencies. This
response will be submitted no later then November 30, 2010.
PG&E Letter DCL-10-134 Page 3 of 5 RAI B2.1.13-4In its August 17, 2010, response to RAI B2.1.13-4, the applicant provided details of the methodology and inspection techniques used for the firewater tank. However, the staff was unclear if the underside of the tank was accessible for the inspections described.
Discussion
- PG&E agreed to supplement its response to RAI B2.1.13-4 to clarify how the underside of firewater tank will be inspected.
PG&E Supplemental Response to Question B2.1.13-4The underside of the firewater tank is inaccessible for visual inspection. PG&E routinely performs visual inspections of the firewater tank internals, as stated previously in PG&E Letter DCL-10-101 dated August 17, 2010. Recent dive inspections have found the
firewater tank bottom to be in good condition. PG&E is currently scheduled to refurbish the firewater tank in 2011. The tank refurbishment will perform ultrasonic thickness (UT) thickness measurements of the firewater tank bottom. PG&E will evaluate UT measurement results and take appropriate corrective action to manage aging effects.
PG&E will perform an additional one-time UT examination of the tank bottom during the 10 years period prior to entering the period of extended operation to confirm its integrity.
License Renewal Application (LRA) Table A4-1 has been revised to state that PG&E will
perform a one-time inspection of the firewater tank bottom using non-intrusive
volumetric examination technique. LRA Section B2.1.13 has been revised to clarify that
the Fire Water System Aging Management Program will be used to manage the overall aging of the fire water tank. LRA Section B2.1.16, One-time Inspection, has been
revised to include a one-time inspection of the firewater tank bottom using nonintrusive
volumetric examination technique prior to the period of extended operation. See
revised LRA Sections A1.13, A1.16, Table A4-1, B2.1.13, and B2.1.16 in Enclosure 2.
PG&E Letter DCL-10-134 Page 4 of 5 RAI B2.1.16-1In its July 7, 2010, response to RAI B2.1.16-1, the applicant provided details of the sampling procedure that will be used for the One-Time Inspection Program. However, the staff was unclear on the basis for the sampling sizes selected for the various aging
effects.Discussion
- PG&E agreed to supplement its response to RAI B2.1.16-1 to provide additional information on the basis for the sampling size and criteria for the program.
PG&E Supplemental Response to Question B2.1.16-1 PG&E letter DCL-10-073 dated June 7, 2010, provided a response to NRC Request for Additional Information (RAI) B2.1.16-1. The basis for the sampling size and
criteria for the program are noted below.
One-Time Inspection - Water Chemistry The Diablo Canyon Power Plant (DCPP) One-Time Inspection (OTI) Program will verify the effectiveness of the Water Chemistry Program at managing material loss by
identifying a population for each in-scope system based on the most susceptible
material within the system (i.e. carbon steel in feedwater system, stainless steel in
chemical and volume control system) at stagnant locations where the full effect of a
Water Chemistry Program may not be achieved. A sample of 10 percent of the
stagnant locations, with the most susceptible material type suitable for ultrasonic
thickness examination will be selected for each in-scope system per unit. The OTI Program will take credit for volumetric examinations performed under other Aging Management Program (AMP), such as flow-accelerated corrosion, when the above
criteria is met and the exams are performed within the 10 years prior to the period of
extended operation.
The DCPP OTI Program will verify the effectiveness of the Water Chemistry Program at managing cracking of stainless steel with temperatures greater than 140
°F by identifying the population of components within in-scope systems that are at stagnant
locations where the full benefit of effective Water Chemistry Program may not be achieved. A sample of 10 percent of this population of stainless steel greater than 140°F in stagnant to low flow locations will be inspected using ultrasonic techniques appropriate to detect cracking. The OTI Program will take credit for volumetric examinations performed under other AMPs, such as Class 1 small bore and in service
inspection, when the above criteria is met and the exams are performed within the 10 years prior to the period of extended operation. In addition to the 10 percent sample of stainless steel greater than 140
°F in stagnant locations, DCPP OTI Program will PG&E Letter DCL-10-134 Page 5 of 5 perform 100 percent eddy current testing of stainless steel tubes in one nonregenerative heat exchanger.
The DCPP OTI Program will verify the effectiveness of the Water Chemistry Program at managing fouling of heat exchanger tubes exposed to treated water by performing a
visual examination of one heat exchanger per in-scope system, function, and
material/environment combination per unit. Consideration of inspectability and
radiological concerns will factor into selecting heat exchangers for this sample.
One-Time Inspection - Fuel Oil Chemistry The DCPP OTI Program will verify the effectiveness of the Fuel Chemistry Program at managing material loss by identifying a population of components within the diesel generator system (DG) and DG fuel transfer system, which are stagnant at lower
elevations that may permit the accumulation of water. A sample of 10 percent of carbon steel piping components identified in the DG system for each diesel as being stagnant
and at a an elevation that would permit water accumulation will be examined using volumetric nondestructive examination techniques. In addition to the piping sample, stainless steel fuel oil priming tank bottoms will be volumetrically examined and carbon steel fuel oil day tanks that permit access to the inside surface of the tank bottom will be
volumetrically examined to the extent accessible. A sample of 10 percent of carbon
steel piping components identified in the DG fuel transfer system for each unit will be volumetrically inspected within the 10 years prior to the period of extended operation.
One-Time Inspection - Lubricating Oil Analysis The DCPP OTI Program will verify the effectiveness of the Lubricating Oil Analysis Program at managing material loss by performing volumetric or visual examinations of one heat exchanger per in-scope system and function per unit. For example, one
copper alloy centrifugal charging pump lube oil cooler per unit out of a population of two coolers per unit will be examined. This sample selection would include aluminum, copper alloy, and carbon steel heat exchanger shells.
PG&E Letter DCL-10-134
Page 1 of 8 LRA Amendment 23 LRA Section RAI A1.13 B2.1.13-4 A1.16 B2.1.13-4 B2.1.13 B2.1.13-4 B2.1.16 B2.1.13-4 Table A4-1 B2.1.13-4 PG&E Letter DCL-10-134
Page 2 of 8 Appendix A Final Safety Analysis Report SupplementA1.13 Fire Water System The Fire Water System program manages loss of material due to corrosion, MIC, or biofouling for water-based fire protection systems. Internal and external inspections and
tests of fire protection equipment are performed considering applicable National Fire
Protection Association (NFPA) codes and standards. The fire water system is managed by performing routine preventive maintenance, inspections, and testing; operator
rounds, performance monitoring, and reliance on the corrective action program; and
system improvements to address aging and obsolescence issues.The Fire Water System program conducts a water flow test through each open spray nozzle to verify that deluge systems provide full coverage of the equipment it protects.
Either periodic non-intrusive volumetric examinations or visual inspections will be
performed on firewater piping. Non-intrusive volumetric examinations would detect loss
of material due to corrosion, and would confirm wall thickness is within acceptable limits
so that aging will be detected before the loss of intended function. Visual inspections
would evaluate (1) wall thickness as it applies to avoidance of catastrophic failure, and (2) the inner diameter of the piping as it applies to the design flow of the fire protection system. The volumetric examination technique employed will be one that is generally
accepted in the industry, such as ultrasonic or eddy current. Inspections of the firewater tank will be performed to detect loss of material.
PG&E Letter DCL-10-134
Page 3 of 8 Appendix A Final Safety Analysis Report SupplementA1.16 One-Time Inspection The One-Time Inspection program conducts one-time inspections of plant system piping
and components to verify the effectiveness of the Water Chemistry program (A1.2), FireWater System program (A1.13), Fuel Oil Chemistry program (A1.14), and Lubricating Oil Analysis program (A1.23). The aging effects to be evaluated by the One-Time Inspection program are loss of material, cracking, and reduction of heat transfer. The
One-Time Inspection program determines non-destructive examination sample size for
each material-environment group using an engineered sampling technique for each
material-environment group based on criteria such as the longest service period, most severe operating conditions, lowest design margins, lowest or stagnant flow conditions, high flow conditions, and highest temperature. The One-Time Inspection program evaluates unacceptable inspection results using the corrective action program.
This new program will be implemented and completed during the 10-year period prior to the period of extended operation. Industry and plant-specific operating experience will
be evaluated in the development and implementation of this program.
PG&E Letter DCL-10-134
Page 4 of 8 Appendix B AGING MANAGEMENT PROGRAMSB2.1.13 Fire Water System Program Description The Fire Water System program manages loss of material due to corrosion, MIC, or biofouling for water-based fire protection systems. Internal and external inspections and
tests of fire protection equipment are performed in accordance with applicable National
Fire Protection Association (NFPA) codes and standards. The fire water system is
managed by performing routine preventive maintenance, inspections, and testing;
operator rounds, performance monitoring, and reliance on the corrective action
program; and system improvements to address aging and obsolescence issues.
The following are activities performed by the Fire Water System program:
Testing: A fire water system flow test is performed at least every three years in accordance with plant procedures meeting requirements of NFPA 25. Hydraulic pump curves are
obtained and compared with baseline curves to determine operability. During the Fire Water System flow test, parameters directly monitored are static pressure and velocity
head.The Fire Water System program conducts a water flow test through each open spray nozzle to verify that deluge systems provide full coverage of the equipment it protects.
The Fire Water System program will be enhanced so sprinkler heads in service for 50
years will be replaced or representative samples from one or more sample areas will be
tested in accordance with NFPA 25. Test procedures will be repeated at 10-year
intervals during the period of extended operation, for sprinklers that were not replaced prior to being in service for 50 years to ensure that signs of degradation, such as
corrosion, are detected prior to the loss of intended function. The Fire Water System program conducts a water flow test through each open spray nozzle of the transformer deluge system periodically to verify that each nozzle is unobstructed. Water is flowed through the test valves of the deluge system periodically
to ensure freedom from blockage.
Fire water is flowed from the Raw Water Storage Reservoir periodically to verify the system piping is capable of delivering the design flow rate.The portable diesel driven fire pumps are tested periodically under full load/full flow conditions.
DCPP performs a hydrostatic test of its indoor fire hoses at least every three years, while outdoor fire hoses are tested at least annually. Fire hoses that are inaccessible
during normal plant operations are tested every refueling outage.
PG&E Letter DCL-10-134
Page 5 of 8 Appendix B AGING MANAGEMENT PROGRAMS Inspections:
Either periodic non-intrusive volumetric examinations or visual inspections will be performed on firewater piping. Non-intrusive volumetric examinations would detect loss
of material due to corrosion, and would confirm wall thickness is within acceptable limits
so that aging will be detected before the loss of intended function. Visual inspections
would evaluate (1) wall thickness as it applies to avoidance of catastrophic failure, and (2) the inner diameter of the piping as it applies to the design flow of the fire protection
system. The volumetric examination technique employed will be one that is generally
accepted in the industry, such as ultrasonic or eddy current.
The Fire Water System program performs periodic visual inspections of main fire system piping, yard loop fire hydrants, hose reel headers, hose stations, portable diesel
driven fire pump hoses, fire hoses, gaskets, water spray headers, sprinkler system
headers, water spray nozzles, and sprinkler heads , and tank to verify they are free of significant corrosion, foreign materials, biofouling, and physical damage.
Tank internal inspection is performed by divers using video and the tank is cleaned as needed at five year frequency. A one
-time UT examination of the fire water tank bottom will be performed as part of the One-Time Inspection aging management program, LRA Section B2.1.16.
DCPP performs a visual inspection of its indoor hose station gaskets once every 18 months, except hose stations in high radiation areas and the containment buildings
which are tested during refueling outages. This inspection ensures that the gaskets
have a satisfactory fit with no defects.
Fire detection instruments located in safety related power block structures, which are accessible during plant operation, are demonstrated to be operable at least once per six
months by testing and surveillance activities. For fire detection instruments located in
safety related power block structures which are not accessible during plant operation, operability is demonstrated during each cold shutdown exceeding 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, unless
performed in the last six months.
PG&E Letter DCL-10-134
Page 6 of 8 Appendix B AGING MANAGEMENT PROGRAMSB2.1.16 One-Time Inspection Program Description The One-Time Inspection (OTI) program conducts one-time inspections of plant system piping and components to verify the effectiveness of the Water Chemistry program
(B2.1.2),Fire Water System program (B2.1.13), Fuel Oil Chemistry program (B2.1.14), and Lubricating Oil Analysis program (B2.1.23). The aging effects to be evaluated by the One-Time Inspection program are loss of material, cracking, and reduction of heat
transfer.The DCPP OTI Program is a new program that will be implemented by DCPP prior to the period of extended operation. The DCPP OTI Program provides measures for
detecting the aging effects prior to loss of intended function, but does not prevent
degradation due to aging effects.
Plant system piping and components identified in the OTI procedure will be subject to OTI using inspection personnel qualified consistent with the ASME Section XI Code and
10 CFR 50, Appendix B. These inspection personnel will follow American Society of
Mechanical Engineers (ASME), Boiler and Pressure Vessel Code,Section V, Nondestructive Examination (NDE), using NDE techniques appropriate to each
inspection. NDE acceptance criteria will be consistent with the design codes/standards or ASME Section XI as applicable to the component for each one-time inspection.
Inspection sample sizes will be determined based on an assessment of materials of fabrication, environment, plausible aging effects and mechanisms, and operating experience. The OTI program determines NDE sample size for each material-
environment group using an engineered sampling technique for each material-
environment group based on criteria such as the longest service period, most severe
operating conditions, lowest design margins, lowest or stagnant flow conditions, high flow conditions, and highest temperature. Component selection will be performed by
the system engineer or other knowledgeable personnel. When evidence of an aging
effect is revealed by a one-time inspection, the engineering evaluation of the inspection
results would identify appropriate corrective actions.
The OTI inspections will be performed during the 10 years prior to the period of extended operation. All one-time inspections will be completed prior to the period of
extended operation. Completion of the OTI Program in this time period will ensure that
confirmation of the absence of aging effects is based upon inspection of components
that have aged for at least 30 years.
Major elements of the DCPP OTI Program will include:
a) Identifying piping and component populations subject to OTI based on common materials and environments, PG&E Letter DCL-10-134
Page 7 of 8 Appendix B AGING MANAGEMENT PROGRAMSb) Determining the sample size of components to inspect for each material-environment group, c) Selecting piping and components within the material-environment groups for inspection based on service period, plausible aging effects, operating conditions and
design margins, d) Conducting one-time inspections of the selected components using ASME Code Section V NDE inspection techniques and acceptance criteria effective in detecting
aging effects of interest,e) An one time UT examination of the firewater tank bottom will be performed.
e f) Evaluating unacceptable inspection results using the corrective action program.
PG&E Letter DCL-10-134
Page 8 of 8 Table A4-1 License Renewal CommitmentsTable A4-1 License Renewal Commitments Item # Commitment LRA Section Implementati on Schedule 51 A one time UT examination of the firewater tank bottom will be performed as part of the One-Time Inspection aging management program, LRA Section B2.1.16.
B2.1.16 During the 10 years prior to the period of extended operation