ML041700593
| ML041700593 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities  |
| Issue date: | 06/18/2004 |
| From: | Rajender Auluck NRC/NRR/DRIP/RLEP |
| To: | |
| Auluck R, NRR/DRIP/RLEP, 415-1025 | |
| References | |
| TAC MB6839, TAC MB6840, TAC MB6841, TAC MB6842 | |
| Download: ML041700593 (12) | |
Text
June 18, 2004 LICENSEE:
EXELON GENERATION COMPANY, LLC FACILITY:
Dresden Nuclear Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2
SUBJECT:
SUMMARY
OF TELEPHONE CONFERENCES HELD ON APRIL 23, AND MAY 6, 2004, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND THE EXELON GENERATION COMPANY, LLC REGARDING COMPRESSED AIR SYSTEMS AT THE DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3, AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (TAC NOS. MB6839, MB6840, MB6841 AND MB6842)
The U.S. Nuclear Regulatory Commission staff (the staff) and representatives of Exelon Generation Company, LLC (EGC or the applicant) held telephone conferences on April 23, and May 6, 2004, to discuss with the applicant the questions raised at the Advisory Committee on Reactor Safeguards (ACRS) subcommittee meeting of April 14, 2004, and the related staff question regarding compressed air system.
The conference calls were useful in clarifying the intent of the staffs questions and the applicants responses. No staff decisions were made during the telephone conferences. provides a listing of the telephone conference call participants. Enclosure 2 contains a listing of questions/clarifications discussed with the applicant, including a brief description on the status of the items. The applicant has had an opportunity to review and comment on this summary.
/RA/
Rajender Auluck, Senior Project Manager License Renewal Section A License Renewal and Environmental Impacts Program Division of Regulatory Improvement Programs Office of Nuclear Reactor Regulation Docket Nos.: 50-237, 50-249, 50-254, and 50-265
Enclosures:
As stated cc w/enclosures: See next page
June 18, 2004 LICENSEE:
EXELON GENERATION COMPANY, LLC FACILITY:
Dresden Nuclear Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2
SUBJECT:
SUMMARY
OF TELEPHONE CONFERENCES HELD ON APRIL 23, AND MAY 6, 2004, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND THE EXELON GENERATION COMPANY, LLC REGARDING COMPRESSED AIR SYSTEMS AT THE DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3, AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (TAC NOS. MB6839, MB6840, MB6841 AND MB6842)
The U.S. Nuclear Regulatory Commission staff (the staff) and representatives of Exelon Generation Company, LLC (EGC or the applicant) held telephone conferences on April 23, and May 6, 2004, to discuss with the applicant the questions raised at the Advisory Committee on Reactor Safeguards (ACRS) subcommittee meeting of April 14, 2004, and the related staff question regarding compressed air system.
The conference calls were useful in clarifying the intent of the staffs questions and the applicants responses. No staff decisions were made during the telephone conferences. provides a listing of the telephone conference call participants. Enclosure 2 contains a listing of questions/clarifications discussed with the applicant, including a brief description on the status of the items. The applicant has had an opportunity to review and comment on this summary.
/RA/
Rajender Auluck, Senior Project Manager License Renewal Section A License Renewal and Environmental Impacts Program Division of Regulatory Improvement Programs Office of Nuclear Reactor Regulation Docket Nos.: 50-237, 50-249, 50-254, and 50-265
Enclosures:
As stated cc w/enclosures: See next page DISTRIBUTION: See next page Accession No: ML041700593 Document Name:C:\\ORPCheckout\\FileNET\\ML041700593.wpd OFFICE LA:RLEP CO-OP:RLEP PM:RLEP SC:RLEP NAME MJenkins DChen RAuluck SLee DATE 6/17/04 6/17/04 6/18/04 6/18/04 OFFICIAL RECORD COPY
DISTRIBUTION: Dated: June 18, 2004 Accession No: ML041700593 HARD COPY RLEP RF R. Auluck (PM)
D. Chen J. Rowley J. Strnisha E-MAIL:
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S. Duraiswamy Y. L. (Renee) Li RLEP Staff L. Rossbach C. Lyon M. Ring, RIII LIST OF PARTICIPANTS FOR TELEPHONE CONFERENCES APRIL 23 AND MAY 6, 2004 April 23, 2004 Participants Affiliation Rajender Auluck U.S. Nuclear Regulatory Commission (NRC)
James Strnisha NRC Steve Gosselin Pacific Northwest National Laboratories (PNNL)
Michael Hayes Exelon Generation Company, LLC. (EGC)
Albert Rulvio EGC May 6, 2004 Participants Affiliation Rajender Auluck NRC James Strnisha NRC David Chen NRC Jonathan Rowley NRC Steve Gosselin PNNL Michael Hayes EGC Mark Kluge EGC Question 1:
What impact has the Dresden compressed air blowdown program had on the reliability of the system, if any? What are the proposed fixes if the blowdown program does not solve the problem? Has a root cause of the moisture been identified?
Discussion: The applicant stated that the question is clear. The applicant stated a re-analysis of the Dresdens operating experience and maintenance history was performed. The review found that the recent occurrences of corrosion, corrosion product buildup and dirt buildup cited in the LRA were not in the instrument air piping. These problems actually occurred in the process fluid portions of these components and were not associated with moisture or dirt buildup in the instrument air system. In 1994, Dresden experienced a loss of instrument air caused by the failure of a corroded carbon steel instrument air pipe connected to the compressed air receiver. The air receiver is not within the license renewal scope. Periodic blowdowns of the air receiver are performed to prevent moisture buildup.
Question 2:
Exelon stated that corrosion, corrosion products, and dirt buildup identified in instrument air system piping, positioners, and valve operators actually occurred in the process fluid portions of these components, not the instrument air portion.
a)
Is this process fluid portion in the scope of license renewal? What was corrective action for this?
Response
The process fluid portions come from several different systems. Most of these components are in the scope of license renewal (e.g. CRD hydraulic accumulators, Reactor Water Clean Up valve, HPCI valve, HVAC drain valve, Fire Pump solenoid, etc.). The only components that are not in the scope of license renewal are components that have been abandoned in place due to previous modifications.
The corrective actions varied for the specific components. The components were cleaned (removed corrosion) or the corroded or worn parts were replaced, tested and returned to service.
b)
Discuss how this re-analysis was performed (i.e. review of work orders, documents, etc.) to determine that problem was not in-scope portion of instrument air. It would be helpful if this was discussed in the cover letter or background section of the revision submitted to the staff.
Response
The aging management review report for the Gas and Ventilation Air Environment was reviewed. All of the Operating Experience entries (Work Orders) that indicated cause of the problem was due to Loss of Material (corrosion) at Dresden were listed. This list included twenty-six Work Orders. All twenty-six Work Orders were reviewed in detail to determine if the proposed blow down of Instrument Air process piping could have prevented the occurrence.
Question 3:
Is the Dresden air receiver listed in Table 3 of the LRA? If the air receiver is not within scope of license renewal, why is aging management performed in the AMP?
a)
The staff could not find the air receiver in the LRA.
b)
The compressed air system is not in scope of license renewal since it is fail-safe.
c)
Explain which air system components are in-scope? Is air needed to operate the MSIVs and PORVs? LRA identifies the following compressed air components:
- 1. RC - valves, tubing
- 2. ESF - tank, piping, fittings, tubing, valves
- 3. Aux - piping, fitting, valve, strainers, filters, tubing
- 4. SPCS - accumulators, filters/strainer, valves.
Response
The Dresden air receiver is not listed in the LRA since the receiver is outside the scope of license renewal. The aging management performed is not to mitigate aging of the receiver. It is performed to prevent moisture accumulation in the receiver as a mitigating function for the down stream portion of the instrument air system.
The portions of the instrument air system that are in the scope of license renewal include the supply to the Outboard MSIVs, CRDs, and safety related HVAC dampers.
The components include local accumulators and boundary check valves.
Additionally, the Drywell Pneumatic System, which is also in the scope of license renewal, supplies the motive force for the Inboard MSIVs and Electromatic Relief Valves.
Question 4:
Exelon stated that trap failure was determined to be the cause of corrosion in the air receiver.
a)
Has the root cause of the trap failure been determined?
b)
Are there similar traps in-scope for license renewal and have the corrective actions been implemented for these traps?
Response
a)
See 8c below.
b)
No.
Discussion: The staff indicated the applicants response is clear.
Question 5:
The revised AMP drafted by Exelon states that Dresden has experienced recent occurrences of corrosion, corrosion product buildup, and dirt in the instrument air system receivers and dryers. Explain the occurrences other than the air receiver failure.
Response
See 2.b above. There were no other instrument air occurrences after this failure.
Question 6:
The revised AMP drafted by Exelon contains the statement, The applicant indicates that Dresden and Quad Cities have not experienced a failure of a pneumatic component within the scope of license renewal due to corrosion, corrosion product buildup, or dirt since 1993. This experience is consistent with the implementation of corrective actions in response to GL 88-14.
Explain the failure that occurred in 1993 and how the corrective actions in response to GL 88-14 corrected this problem.
Response
The actual date of failure was April 30, 1994. The threaded piping on the inlet side of the 2A instrument air receiver broke, allowing the system to depressurize. This piping is not in the scope of license renewal. The corrective actions associated with the event are discussed in 7c below.
Question 7:
What will final revision look like? It should be a revised AMP write-up from the LRA, not a markup of the SER.
Response
See B.1.16 revision on page 5.
Question 8:
Additional questions raised at the ACRS subcommittee meeting:
a)
What impact has the Dresden compressed air blowdown program had on the reliability of the system, if any? With respect to moisture and corrosion in the receiver and downstream piping, the periodic blowdown program implemented at Dresden appears to have been effective in preventing any further occurrence.
Were there any changes to the scheduled preventive maintenance activities (e.g., for the traps) for instrument air components as a result of the problem?
b)
What are the proposed fixes if the blowdown program does not solve the problem? In this case, the blowdown program has prevented any reoccurrence; however, we are not sure exactly what the root-cause of the failure was and what corrective actions were done to fix that.
c)
Has the root cause of the moisture been identified?
Response
a)
There have been no additional failures since 1994.
b)
The compressor receiver tank, moisture separator, drain traps and portions of the inlet and discharge pipe were replaced. A check valve was installed at the receiver discharge to prevent header depressurization following a tank, compressor, relief valve or pipe failure. The inlet/outlet piping was replaced using a stainless steel material and an epoxy coating was applied to the receiver tanks. An improved moisture trap design was installed which is much less susceptible to debris plugging. Periodic blowdowns of the air receiver are performed to prevent moisture buildup. These corrective actions have been effective in preventing recurrence.
c)
Moisture and condensation are a natural byproduct of compressing air. The root cause of the failure was oxidation of the carbon steel pipe in the presence of moisture leading to mechanical failure of the threaded portion of the inlet air supply piping to the Unit 2A Instrument Air Receiver Tank. The layered appearance of the oxide indicates the corrosion had taken place over a period of years, the pipe eventually failed when it could no longer withstand system operating pressure. Contributing to this failure was the threaded receiver inlet and discharge connections versus a welded flange connection.
The moisture separator drain trap was connected at a sight glass port five (5) inches above the base of the tank. A manual drain valve was connected at the base of the moisture separator. A 12 x 5 inch rectangular section was cut from the moisture separator to facilitate destructive examination. The tank base drain location was found plugged solid with debris, approximately two to three inches of rust and scale had accumulated in the base of the tank. This debris apparently prevented the trap from performing its function.
The following is the revised LRA Section B.1.16 B.1.16 Compressed Air Monitoring Description The compressed air monitoring aging management program activities manage loss of material due to general, crevice, and pitting corrosion for portions of the instrument air system within the scope of license renewal. Program activities consist of air quality testing, pressure decay testing, and visual inspections at various system locations. The activities are consistent with Dresden and Quad Cities responses to NRC Generic Letter 88-14, Instrument Air Supply Problems, and ANSI/ISA-S7.3-1975, Quality Standard for Instrument Air. Testing and monitoring activities are implemented through station specific procedures and associated predefined tasks.
NUREG-1801 Consistency With enhancements the compressed air monitoring aging management program is consistent with the ten elements of aging management program XI.M24, Compressed Air Monitoring, specified in NUREG-1801 with the following exceptions.
Exceptions to NUREG-1801 NUREG-1801 indicates that the program is based on responses to GL 88-14 and INPO SOER 88-01, Instrument Air System Failures, as well as EPRI NP-7079-1990, EPRI TR-108147, Compressor and Instrument Air System Maintenance Guide, ASME OM-S/G-1998 and ANSI/ISA-S7.0.01-1996. The Dresden and Quad Cities programs are based on the guidance provided in the GL 88-14 and ANSI/ISA-S7.3-1975 documents, which are part of the current licensing basis. Enhancements include inspection of instrument air distribution piping based on EPRI TR-108147.
NUREG-1801 indicates that inservice inspection and testing is performed to verify proper air quality, and confirm that maintenance practices, emergency procedures and training are adequate to ensure that the intended function of the air system is maintained. Inservice inspections at Dresden and Quad Cities do not verify air quality because air quality testing is performed in accordance with specific procedures based on ANSI/ISA-S7.3-1975. Maintenance practices, emergency procedures, and training are plant performance issues that are not directly related to aging management of the instrument air systems. Aging management consists of air quality tests and pressure decay tests of MSIV and safety/relief valve pneumatic systems including accumulators, piping, and check valves, and periodic inspections to verify the integrity of the systems.
Enhancements
The program will provide for new periodic inspections for those portions of instrument air distribution piping at Dresden and Quad Cities that are within the scope of the rule.
The program will provide for periodic blowdowns of instrument air receivers located upstream of the instrument air system dryers at Dresden.
Enhancements are scheduled for implementation prior to the period of extended operation.
Operating Experience Dresden has experienced occurrences of corrosion, corrosion product buildup, and dirt buildup in instrument air system receivers and dryers. The program enhancement of providing periodic blowdowns of instrument air receivers addresses this condition.
Dresden and Quad Cities have not experienced a failure of a pneumatic component within the scope of license renewal due to corrosion, corrosion product buildup, or dirt buildup since 1993. This experience is consistent with the implementation of corrective actions in response to GL 88-14.
Dresden and Quad Cities have experienced equipment failures including MSIVs, dampers, and process valves due to instrument air leaks. These failures were to individual components and did not propagate to other components within the system.
Dresden and Quad Cities have not experienced a common mode failure caused by the instrument air system. The Dresden and Quad Cities enhancements of performing predefined tasks that require periodic inspections of instrument air distribution piping address this condition.
Conclusion The compressed air monitoring aging management program provides reasonable assurance that loss of material aging effects are adequately managed so that the intended functions of the instrument air components within the scope of license renewal are maintained during the period of extended operation.
Dresden and Quad Cities Nuclear Power Stations cc:
Site Vice President - Quad Cities Nuclear Power Station Exelon Generation Company, LLC 22710 206th Avenue N.
Cordova, IL 61242-9740 Quad Cities Nuclear Power Station Plant Manager Exelon Generation Company, LLC 22710 206th Avenue N.
Cordova, IL 61242-9740 Regulatory Assurance Manager - Quad Cities Exelon Generation Company, LLC 22710 206th Avenue N.
Cordova, IL 61242-9740 Quad Cities Resident Inspectors Office U.S. Nuclear Regulatory Commission 22712 206th Avenue N.
Cordova, IL 61242 William D. Leech Manager - Nuclear MidAmerican Energy Company P.O. Box 657 Des Moines, IA 50303 Vice President - Law and Regulatory Affairs MidAmerican Energy Company One River Center Place 106 E. Second Street P.O. Box 4350 Davenport, IA 52808 Chairman Rock Island County Board of Supervisors 1504 3rd Avenue Rock Island County Office Bldg.
Rock Island, IL 61201 Regional Administrator U.S. NRC, Region III 801 Warrenville Road Lisle, IL 60532-4351 Document Control Desk-Licensing Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Senior Vice President - Nuclear Services Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Vice President - Engineering Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Chief Operating Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Director - Licensing Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Senior Counsel, Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Manager Licensing - Dresden and Quad Cities Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Robert E. Stachniak Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
Mr. Fred Emerson Nuclear Energy Institute 1776 I Street, N.W., Suite 400 Washington, DC 20006-3708 Site Vice President - Dresden Nuclear Power Station Exelon Generation Company, LLC 6500 N. Dresden Road Morris, IL 60450-9765 Dresden Nuclear Power Station Plant Manager Exelon Generation Company, LLC 6500 N. Dresden Road Morris, IL 60450-9765 Regulatory Assurance Manager - Dresden Exelon Generation Company, LLC 6500 N. Dresden Road Morris, IL 60450-9765 Dresden Resident Inspectors Office U.S. Nuclear Regulatory Commission 6500 N. Dresden Road Morris, IL 60450-9766 Chairman Grundy County Board Administration Building 1320 Union Street Morris, IL 60450 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, IL 62704 Vice President - Licensing and Regulatory Affairs Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Frederick W. Polaski Manager - License Renewal Program Exelon Generation Company, LLC 200 Exelon Way, KSA 1-N-3 Kennett Square, PA 19348