NL-04-1419, Technical Specification Revision Request Integrated Leakage Rate Testing Interval Extension
| ML042330373 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 08/17/2004 |
| From: | Sumner H Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-04-1419 | |
| Download: ML042330373 (7) | |
Text
H.L Sumner, Jr. Southern Nuclear Vice President Operating Company, Inc.
Hatch Project . in Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.7279 SOUTHERNAM August 17, 2004 COMPANY Energy to Serve YourWorldd' Docket No.: 50-366 NL-04-1419 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Hatch Nuclear Plant Unit 2 Technical Specification Revision Request Integrated Leakage Rate Testing Interval Extension Ladies and Gentlemen:
By this letter, Southern Nuclear Operating Company (SNC) provides additional information that addresses certain topics discussed in telecons on June 21, July 6, and August 4, 2004 between the NRC staff and SNC personnel. The questions and responses regarding inspection information are shown on Attachment 1.
Also, risk assessment questions were discussed. Additional information related to the risk assessment questions will be provided by separate correspondence.
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely, H. L. Sumner, Jr.
HLS/whc/daj
Enclosure:
Attachment I - Inspection Information cc: Southern Nuclear Operating Company Mr. J. B. Beasley, Jr., Executive Vice President Mr. G. R. Frederick, General Manager - Plant Hatch RTYPE: CHAO2.004 U. S. Nuclear Regulatory Commission Dr. W. D. Travers, Regional Administrator Mr. C. Gratton, NRR Project Manager - Hatch Mr. D. S. Simpkins, Senior Resident Inspector - Hatch 0
Hatch Nuclear Plant Unit 2 Technical Specification Revision Request Integrated Leakage Rate Testing Interval Extension Attachment 1 The following additional information is provided as clarification of topics noted in telecoms with the NRC.
- 1. NRC Ouestion In response to the NRC's simulated question 6, the licensee indicates that during the 2R17 outage in spring of 2003, the licensee had fully replaced the mastic seal between the drywell shell and the concrete floor. The action indicates that the original seal was degraded. The license is requested to provide the results of the drywell shell examination performed prior to the seal replacement. If the area is found to be susceptible to water damage, the licensee is requested to justify why this area should not be identified for augmented examinations as required by IWE-1240.
SNC Response Inspection of the seal at the steel liner plate and concrete floor interface inside the drywell at 114' elevation was performed during the Spring 2000 Unit 2 Outage. Results of the inspection revealed three areas where the mastic seal had either been damaged or was disbanded from the steel liner. One of the areas was approximately 2 feet in length and the other two were approximately 10 inches (each) in length.
CR2000002021 was generated and repairs were initiated in accordance with MWO20000662. The mastic material in these three areas was removed and a protective coating was applied to the containment shell, however, because of very wet conditions created by other work in the area, successful repair of the seal was questionable.
On 3/29/00, certified personnel visually examined all three areas and scanned all accessible surfaces of all three areas with an ultrasonic thickness meter to determine the minimum shell thickness. The minimum ultrasonic thickness measurement was recorded for each area.
Area #1 - Minimum Thickness = 1.500" Area #2 - Minimum Thickness = 1.475" Area #3 - Minimum Thickness = 1.615" The ISI Plan, Volume 3, Figure HNP-IWE-05, indicates a nominal shell thickness of 1.5" and a minimum design thickness of 1.36" in this area. This drawing was developed from the CBI design report for the drywvell.
An engineering evaluation was performed and it was determined that repair of the seal could be deferred.
The mastic seal was reinspected during the Unit 2 Fall 2001 Refueling Outage. CR 2001009111 was generated to document the inspection results. It was determined that full replacement of the mastic seal was appropriate and would be most successful if performed during the Spring 2003 Refueling Outage due to the large Fall 2001 work scope in the same area (e.g. replacement of both recirculation pumps).
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Hatch Nuclear Plant Unit 2 Technical Specification Revision Request Integrated Leakage Rate Testing Interval Extension Attachment 1 SNC Responsc (continued)
SNC has been monitoring both coated and un-coated steel surfaces in the drywell and torus for several years and has noted very low corrosion rates during an operating cycle. This is primarily because of the high nitrogen, low oxygen content that is present in the drywell and torus when the plant is operating. SNC has been measuring and monitoring the corrosion rates in the immersion areas of the torus since 1993, and has documented that it is less than 3 mils. per year (average) during plant operation.
The liner plate in the repair areas was coated prior to installing the mastic seal, but even if some of the coating has failed and water collects in these areas (creating an immersion environment) and remains until next outage, metal loss due to corrosion should be less than 5 mils. Bare substrate in immersion should be the worst case condition.
If moisture migrates between the concrete and steel liner in the repair areas, this should also be of little concern from a corrosion standpoint. The calcium and other alkaline constituents of the concrete provide an environment that has a high PH which inhibits corrosion (even with moisture present).
MWO20103141 was implemented during the Spring 2003 Refueling Outage to remove and replace the mastic seal.
- 2. NRC Question In response to the NRC's simulated question 4, the licensee states: "Experience indicates that conventional examination techniques are not adequate to identify defects in the bellows, and presently Appendix J testing is the only practical test method currently being performed." If the bellows are not designed for detection of bellows degradation by Appendix J, Type B testing the licensee is requested to justify why the Type A test should not be performed as required by the existing Technical Specification.
SNC Response Information Notice 92-20 indicated that bellows leakage may not be accurately measured by Appendix J Type B testing for some bellows configurations. In response to IN92-20, Plant Hatch installed temporary plates on some selected bellows penetrations (a labor and outage schedule intensive activity) and performed a simulated Type A leakage test. These leakage tests indicated that the Type B leakage test is a representative test. The licensee answer (in SNC's original submittal) indicates that Appendix J Type B testing is considered adequate to detect bellows degradation, but alternatives to conventional examination techniques (visual, dye penetrant, radiography, etc....) continue to be evaluated.
- 3. NRC Ouestion In describing the results of prior inspections in the Table containing response June 17, 2004 to the NRC's simulated question 6, the licensee in each case states: "No significant pressure boundary degradation was identified." The licensee is requested to provide description of the criteria used to identify "significant pressure boundary degradation".
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Hatch Nuclear Plant Unit 2 Technical Specification Revision Request Integrated Leakage Rate Testing Interval Extension Attachment 1 SNC Response Plant Hatch procedure 42SV-L23-001-OS "Protective Coating Surveillance Inspection," 42SV-T23-003-OS, "Drywell Surfaces Visual Inspection," and 42SV-SUV-047-OS, "Venting Assembly and Suppression Chamber Surfaces Visual Inspection" all contain acceptance criteria consistent with ASME Section XI Subsection IWE.
Degradation that is not detrimental, such as general surface corrosion or light surface pitting that is of no concern to the integrity of the pressure retaining boundary should not be considered as reportable; however, evidence of OR actual existence of the following (or similar) conditions shall be reported and brought to the attention of the CIPRE for evaluation:
- Miscellaneous damage, deformation, or degradation (any condition that could potentially be detrimental to the component integrity) such as cracks, tears, broken welds, etc.
The inspector may use the following guidelines in determining reportability of the following conditions having depth:
40 mils: Drywell Shell (interior and exterior) 50 mils: Torus Shell Vapor Space (interior and exterior) 60 mils: Torus Shell Wetted Surfaces (interior and exterior) oExcessive corrosion/pitting (generally represented by dark discoloration (red/brown), spalling from swelling, rust ejection, deep pits, and/or other severe manifestations)
- Deep gouges or dents (excluding fabrication or installation marks)
- Excessive wear (generally represented by shiny wastage)
Personnel performing the examination will ensure that lighting and access are adequate to identify the conditions described above.
- 4. NRC Ouestion In response to the NRC's simulated question 6 (question 3 in originalsubmittal), the licensee cites Relief Requests RR-MC-1, RR-MC-6, and RR-MC-8 for examination of seals, gaskets, and bolting associated with the containment pressure boundary penetrations. For penetrations (other than equipment hatch and air-locks, which are Type B tested after each opening) with seals, gaskets, and pressure-retaining bolting, reliance has been placed on the frequency of Type A and Type B testing to detect their degradation. As the performance based Type B test interval for these penetrations could be as high as 10 years, and with the request to extend the Type A test interval to 15 years, provide information to demonstrate that the integrity of the seals, gaskets, and bolting associated with the mechanical and electrical penetrations, and drywell head will be maintained.
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Hatch Nuclear Plant Unit 2 Technical Specification Revision Request Integrated Leakage Rate Testing Interval Extension Attachment 1 SNC Response The justification for extension of most Type B test intervals to 10 years in conjunction with extension of the Type A test interval has already been reviewed by the staff as documented in RG 1.163. The incremental increase in risk associated with extending the Type A test interval to 15 years while maintaining the Type B test interval at 10 years is documented in our submittal.
Electrical penetrations at Plant Hatch do not have pressure retaining bolting and conductor penetrations are sealed by cast epoxy. The penetrations are nitrogen pressurized during normal operation and pressures are periodically monitored. Furthermore, at least one electrical penetration of each type is Type B tested each operating cycle.
The drywell head is removed each operating cycle. The bolting and seal are examined in accordance with RR-MC-I and RR-MC-6. Type B leakage testing is performed every operating cycle.
The highlighted mechanical penetrations in the attached table are the only mechanical penetrations which may not be Type B tested every operating cycle and examined in accordance with RR-MC-1 and RR-MC-6. Outage and maintenance activities generally require disassembling most mechanical penetrations which would result in a Type B leakage test upon reassembly. As a minimum they will be disassembled, inspected, and tested at least once every 10 years in accordance with RR-MC-8.
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Hatch Nuclear Plant Unit 2 Technical Specification Revision Request Integrated Leakage Rate Testing Interval Extension Attachment I PEN TYPE NUMBER DESCR ORIENT TYPE IA Double O-Ring 001A-B1 Equipment Hatch Inboard B IB Double O-Ring 001B-B1I Equipment Hatch Inboard B 2 Barrel 002-B3 Personnel Airlock Innerspace In / Out B 2 Double O-Ring 002-B I Personnel Airlock Inboard B 2 Double O-Ring 002-B2 Personnel Airlock Outboard B 4 Double O-Ring 004-B I Drywell Head Access Hatch Inboard B 6 Double O-Ring 006-B I CRD Removal Hatch Inboard B 25 2T48-F103 Double O-Ring "A" 025-BOI Drywell Purge Supply Outboard B 25 2T48-F103 Double O-Ring "B" 025-B02 Drywvell Purge Supply Outboard B 25 2T48-F103 Double O-Ring "C" 025-B03 Drywell Purge Supply Outboard B 25 2T48-F 103 Double O-Ring "D" 025-B04 Drywell Purge Supply Outboard B 25 2T48-F307 Double O-Ring "A" 025-B05 Drywell Purge Supply Outboard B 25 2T48-F307 Double O-Ring "B" 025-B06 Drywell Purge Supply Outboard B 25 2T48-F307 Double O-Ring "C" 025-B07 Drywell Purge Supply Inboard B 25 2T48-F307 Double O-Ring "D" 025-B08 Drywell Purge Supply Outboard B 25 2T48-F308 Double O-Ring "A" 025-B09 Drywyell Purge Supply Outboard B 25 2T48-F308 Double O-Ring "B" 025-BI0 Drywell Purge Supply Outboard B 25 2T48-F308 Double O-Ring "C" 025-B I I Drywell Purge Supply Outboard B 25 2T48-F308 Double O-Ring "D" 025-B12 Drywell Purge Supply Outboard B 26 2T48-F319 Double O-Ring "A" 026-BI Drywell Main Exhaust Outboard B 26 2T48-F319 Double O-Ring "B" 026-B2 Drywell Main Exhaust Outboard B 26 2T48-F319 Double O-Ring "C" 026-B3 Drywell Main Exhaust Inboard B 26 2T48-F319 Double O-Ring "D" 026-B4 Drywell Main Exhaust Outboard B 26 2T48-F320 Double O-Ring "A" 026-B5 Drywvell Main Exhaust Outboard B 26 2T48-F320 Double O-Ring "B" 026-B5 Drywell Main Exhaust Outboard B 26 2T48-F320 Double O-Ring "C" 026-B5 Drywell Main Exhaust Outboard B 26 2T48-F320 Double O-Ring "D" 026-B5 Drywell Main Exhaust Outboard B 35A Double O-Ring 035A-BI TIP Drive D - Inboard B 35B Double O-Ring 035B-BI-- TIP Drive A Inboard B 35C Double 0-Ring 035C-BI TIP Drive C Inboard B 35D Double O-Ring 035D-BI TIP Drive B Inboard B 35E Double O-Ring 035E-BI TIP N2 Purge - Inboard B 43 Double O-Ring -043-B 1 Drywell Test and Fill Inboard B 82 Double O-Ring 082-B I Drywell Head Flange Inboard B 83A Double O-Ring -083A-BI RPV Stabilizer Access Hatch Inboard B 83B - Double -Ring 083B-BI RPV Stabilizer Access Hatch Inboard B 83C Double O-Ring 083C-BI RPV Stabilizer Access Hatch Inboard B 83D -Double O-Ring 083D-BI RPV Stabilizer Access Hatch Inboard B 83E Double O-Ring 083E-BI RPV Stabilizer Access Hatch Inboard -B 83F Double O-Ring 083F-BI RPV Stabilizer Access Hatch Inboard B 83G -- Double O-Ring :083G-BI RPV Stabilizer Access Hatch Inboard B 83H Double O-Ring 083H-BI RPV Stabilizer Access Hatch Inboard B El-S
Hatch Nuclear Plant Unit 2 Technical Specification Revision Request Integrated Leakage Rate Testing Interval Extension Attachment I PEN TYPE NUMBER DESCR ORIENT TYPE 200A Double O-Ring 200A-B1 Torus Access Hatch Inboard B 200B Double O-Ring 200B-B I Torus Access Hatch Inboard B 205 2T48-F309 Double O-Ring "A" 205-BOI Torus Purge Supply Outboard B 205 2T48-F309 Double O-Ring "B" 205-B02 Torus Purge Supply Outboard B 205 2T48-F309 Double O-Ring "C" 205-B03 Torus Purge Supply Inboard B 205 2T48-F309 Double O-Ring "D" 205-B04 Torus Purge Supply Outboard B 205 2T48-F310 Double O-Ring "A" 205-B05 Vacuum Relief Outboard B 205 2T48-F310 Double O-Ring "B" 205-B06 Vacuum Relief Outboard B 205 2T48-F310 Double O-Ring "C" 205-B07 Vacuum Relief Inboard B 205 2T48-F3 10 Double O-Ring "D" 205-B08 Vacuum Relief Outboard B 205 2T48-F311 Double O-Ring "A" 205-B09 Vacuum Relief Outboard B 205 2T48-F311 Double O-Ring "B" 205-BIO Vacuum Relief Outboard B 205 2T48-F311 Double O-Ring "C" 205-BI I Vacuum Relief Inboard B 205 2T48-F311 Double O-Ring "D" 205-B12 Vacuum Relief Outboard B 205 2T48-F324 Double O-Ring "A" 205-B115 Torus Purge Supply Outboard B 205 2T48-F324 Double O-Ring "B" 205-B15 Torus Purge Supply Outboard B 205 2T48-F324 Double O-Ring "C" 205-B115 Torus Purge Supply Outboard B 205 2T48-F324 Double O-Ring "D" 205-B115 Torus Purge Supply Outboard B 218B Double O-Ring 218B-B I 'Construction Drain Inboard B 220 2T48-F318 Double O-Ring "A" 220-BI Torus Main Exhaust Outboard B 220 2T48-F318 Double O-Ring "B" 220-B2 Torus Main Exhaust Outboard B 220 2T48-F318 Double O-Ring "C" 220-B3 Torus Main Exhaust Inboard B 220 2T48-F318 Double O-Ring "D" 220-B4 Torus Main Exhaust Outboard B 220 2T48-F326 Double O-Ring "A" 220-B7 Torus Main Exhaust Outboard B 220 2T48-F326 Double O-Ring "B" 220-B7 Torus Main Exhaust Outboard B 220 2T48-F326 Double O-Ring "C" 220-B7 Torus Main Exhaust Outboard B 220 2T48-F326 Double O-Ring "D" 220-B7 Torus Main Exhaust Outboard B 223A Double O-Ring 223A-B I Spare - Inboard B 223B . Double 0-Ring: 223B-BI3 Spare - Inboard B 228B . DoubleO-Ring 228B-BI Low Voltage Power (spare) Inboard B 236 Double O-Ring 236-BI Torus Access Hatch Inboard B E1-6