ML18093A977
| ML18093A977 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 07/20/1988 |
| From: | Miltenberger S Public Service Enterprise Group |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NLR-N88111, NUDOCS 8807280353 | |
| Download: ML18093A977 (6) | |
Text
Public Service Electric and Gas Company Steven E. Miltenberger Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-4199 Vice President and Chief Nuclear Officer JUL 2 O 1988 NLR-N88111 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:
ALTERNATE REPAIR, SUPPLEMENT 1 CONTAINMENT FAN COIL UNIT SERVICE WATER PIPING FACILITY OPERATING LICENSE NO. DPR-75 SALEM GENERATING STATION UNIT NO. 2 DOCKET NO. 50-311 Public Service Electric and Gas Company (PSE&G) requested, by letter dated July 13, 1988, approval of an alternate repair on No. 25 Containment Fan Coil Unit (CFCU) Service Water piping.
Subsequent to this, the NRC requested further detail as to the hardship involved and the cause of the Service Water piping corrosion.
This information is provided in the Attachment.
Should you have any questions, please contact us immediately.
Sincerely, Attachment
Document Control Desk 2
C Mr. D. c. Fischer USNRC*Licensing Project Manager Mr. R. w. Borchardt USNRC Senior Resident Inspector Mr. w. T. Russell, Administrator USNRC Region I Mr. D. M. Scott, Chief Bureau of Nuclear Engineering Department of Environmental Protection 380 Scotch Road Trenton, NJ 08628 JUL 2 0 1988
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ATTACHMENT 10CFR50.55a requires the service water piping to be maintained in accordance with.the ASME Section XI Code requirements.
The regulation further requires that if licensees determine that conformance to code requirements is impractical, information shall be submitted supporting this determination.
Per 10 CFR 50.55a(g)(6)(i), the Commission will evaluate determinations that code requirements are impractical.
PSE&G believes that performing a code repair of the pin hole leak on the No. 25 CFCU service water vent line is impractical and presents an unnecessary hardship.
This is based on the fact that the repair needs to be made in the Containment Building.
This is a high temperature, high humidity, radiation area.
The temperature in the vicinity of the leak is above 120°F.
The OSHA stay time requirement is 15 minutes at this temperature.
The proposed weld overlay repair provides an acceptable level of quality and safety and can be performed in significantly less time than the code repair (estimated time savings is more than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />).
This will significantly reduce the risk of heat exhaustion to the maintenance and radiation protection personnel.
Radiation exposure will also be reduced as a result of this significant time reduction.
The repair will be considered temporary and will be inservice for just over seven weeks, as an appropriate code repair will be performed during the fourth refueling outage.
The weld overlay technique is a proven temporary repair technique that will ensure the integrity of the subject weld.
If the weld were to fail, the leakage would be easily detected at less than 1 gpm, by the containment leakage detection system.
Consequently, the weld overlay provides sufficient integrity, while significantly reducing the time of the repair.
This will reduce the risk of heat exposure to the individuals involved and also reduce radiation exposure.
As such, PSE&G believes that this is the best repair to make under present plant conditions.
Therefore, PSE&G requested code relief and approval of the weld overlay as an alternative repair on the basis that the code repair is impractical for the present plant situation.
Salem has experienced significant problems with service water erosion and corrosion effects.
This is attributed to the fact that the supply water is very high in sediment content and extremely brackish.
For this weld, the postulated failure mechanism is accelerated corrosion due to a high chloride and high oxygen environment.
This vent connection is at the high point in the system.
After the initial venting, the line remains stagnent with any oxygen that was still entrained in the system eventually collecting in this area.
Consequently, the coirosion rate is accelerated by the high oxygen/chloride environment in the stagnent carbon steel line.
PSE&G organized a Service Water Project Team in April of 1987 to identify problem areas, establish inspection programs and develop repair, replacement and system upgrade plans for the service water system.
A project overview is enclosed outlining the system monitoring, modification and upgrades.
One of the major upgrades of the project is to replace much of the existing piping with 6% molydenum stainless steel material. The 6%
molydenum stainless steel was chosen based on the fact that it is less susceptible to microbiologically-induced corrosion (MIC) and chemical attacks than other suitable materials.
The 6%
molydenum stainless steel is also more resistant to erosion.
The material has been used successfully in European applications and has been used successfully for 7 years in Salem condensers.
An ongoing material test program has demonstrated the improved corrosion resistance of the 6% molydenum stainless material.
ENCLOSURE I PROJECT OVERVIEW 0 SYSTEM UPGRADES
- PIPING REPLACEMENT WITH 6% MOLY STAINLESS IN SELECTED AREAS
- PIPING DESIGN IMPROVEMENTS
- SELECTED EQUIPMENT UPGRADE OF MATERIALS/DESIGN
- CONTROL MODIFICATIONS 0 CONTINUED SYSTEM PERFORMANCE MONITORING
- ONGOING "IN LINE" MATERIAL TEST PROGRAM
- CONTINUED SYSTEM INSPECTIONS AND TRENDING OF RESULTS
- "DAY TO DAY" INVOLVEMENT IN STATION SERVICE WATER ACTIVITIES
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PROJECT -OVERVIEW CONTINUED 0 PIPING UPGRADES
- CUNTAINMENT FAN COIL UNITS
- COMPONENT COOLING HEAT EXCHANGER
- CHILLER CONDENSERS
- OUTSIUE CONTAINMENT PENETRATION AREA
- PENETRATION AREA VALVE ROOMS
- PUMP ROOM COOLERS
- SW PUMP SERVICES
- INTAKE STRUCTURE DISTRIBUTION HEADERS
- VARIOUS TURBINE AREA HIGH EROSION LOCATIONS 0 EQUIPMENT UPGRADES
- REPLACEMENT OF ALL Cl2) PUMP DISCHARGE STRAINERS
- REPLACEMENT OF ALL Cl4> INTAKE STRUCTURE MOV'S
- REPLACEMENT OF Cl4> INTAKE STRUCTURE RUBBER EXPANSION JOINTS WITH HARD PIPE r:
- SERVICE WATER PUMP MATERIALS <IMPELLERS ETC.)
0 CONTROL MODIFICATIONS
- CAVITATION MITIGATION ON COMPONENT COOLING HEAT EXCHANGERS
- CONTINUOUS FLOW ON CONTAINMENT FAN COIL UNITS
- INSTALLATION OF IMPROVED PUMP FLOW MEASUREMENT EQUIPMENT