1801 R2 XI.M30

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XI.M30 FUEL OIL CHEMISTRY

Program Description

The program includes (a) surveillance and maintenance procedures to mitigate corrosion and (b) measures to verify the effectiveness of the mitigative actions and confirm the insignificance of an aging effect. Fuel oil quality is maintained by monitoring and controlling fuel oil contamination in accordance with the plant’s technical specifications. Guidelines of the American Society for Testing Materials (ASTM) Standards, such as ASTM D 0975-04, D 1796-97, D 2276-00, D 2709-96, D 6217-98, and D 4057-95, also may be used. Exposure to fuel oil contaminants, such as water and microbiological organisms, is minimized by periodic draining or cleaning of tanks and by verifying the quality of new oil before its introduction into the storage tanks. However, corrosion may occur at locations in which contaminants may accumulate, such as tank bottoms. Accordingly, the effectiveness of the program is verified to ensure that significant degradation is not occurring and that the component’s intended function is maintained during the period of extended operation. Thickness measurement of tank bottom surfaces is an acceptable verification program.

The fuel oil chemistry program is generally effective in removing impurities from intermediate and high flow areas. This report identifies those circumstances in which the fuel oil chemistry program is to be augmented to manage the effects of aging for license renewal. For example, the fuel oil chemistry program may not be effective in low flow or stagnant flow areas. Accordingly, in certain cases as identified in this report, verification of the effectiveness of the chemistry program is undertaken to ensure that significant degradation is not occurring and that the component’s intended function is maintained during the period of extended operation. As discussed in this report for these specific cases, an acceptable verification program is a onetime inspection of selected components at susceptible locations in the system.

Evaluation and Technical Basis

1. Scope of Program: Components within the scope of the program are the diesel fuel oil storage tanks, piping, and other metal components subject to aging management review that are exposed to an environment of diesel fuel oil. The program is focused on managing loss of material due to general, pitting, crevice, and microbiologically-influenced corrosion (MIC) and fouling that leads to corrosion of the diesel fuel tank internal surfaces.

2. Preventive Actions: The program reduces the potential for (a) exposure of the storage tanks’ internal surface to fuel oil contaminated with water and microbiological organisms, reducing the potential for age-related degradation in other components exposed to diesel fuel oil; and (b) transport of corrosion products, sludge, or particulates to components serviced by the fuel oil storage tanks. Biocides or corrosion inhibitors may be added as a preventive measure or are added if periodic testing indicates biological activity or evidence of corrosion. Periodic cleaning of a tank allows removal of sediments, and periodic draining of water collected at the bottom of a tank minimizes the amount of water and the length of contact time. Accordingly, these measures are effective in mitigating corrosion inside diesel fuel oil tanks. Coatings, if used, prevent or mitigate corrosion by protecting the internal surfaces of the tank from contact with water and microbiological organisms.

3. Parameters Monitored/Inspected: The program is focused on managing loss of material due to general, pitting, crevice, and MIC, and fouling that leads to corrosion of the diesel fuel tank internal surfaces. The aging management program monitors fuel oil quality through receipt testing and periodic sampling of stored fuel oil. Parameters monitored include water and sediment content, total particulate concentration, and the levels of microbiological organisms in the fuel oil. Water and microbiological organisms in the fuel oil storage tank increase the potential for corrosion. Sediment and total particulate content may be indicative of water intrusion or corrosion.

4. Detection of Aging Effects: Loss of material due to corrosion of the diesel fuel oil tank or other components exposed to diesel fuel oil cannot occur without exposure of the tank’s internal surfaces to contaminants in the fuel oil, such as water and microbiological organisms. Periodic multilevel sampling provides assurance that fuel oil contaminants are below unacceptable levels. If tank design features do not allow for multilevel sampling, a sampling methodology that includes a representative sample from the lowest point in the tank may be used.

At least once during the 10-year period prior to the period of extended operation, each diesel fuel tank is drained and cleaned, the internal surfaces are visually inspected (if physically possible) and volumetrically-inspected if evidence of degradation is observed during visual inspection, or if visual inspection is not possible. During the period of extended operation, at least once every 10 years, each diesel fuel tank is drained and cleaned, the internal surfaces are visually inspected (if physically possible), and, if evidence of degradation is observed during inspections, or if visual inspection is not possible, these diesel fuel tanks are volumetrically inspected.

Prior to the period of extended operation, a one-time inspection (i.e., AMP XI.M32) of selected components exposed to diesel fuel oil is performed to verify the effectiveness of the Fuel Oil Chemistry program.

5. Monitoring and Trending: Water, biological activity, and particulate contamination concentrations are monitored and trended in accordance with the plant’s technical specifications or at least quarterly.

6. Acceptance Criteria: Acceptance criteria for fuel oil quality parameters are as invoked or referenced in a plant’s technical specifications. Additional acceptance criteria may be implemented using guidance from industry standards and equipment manufacturer or fuel oil supplier recommendations. ASTM D 0975-04 or other appropriate standards may be used to develop fuel oil quality acceptance criteria. Suspended water concentrations are in accordance with the applicable fuel oil quality specifications. Corrective actions are taken if microbiological activity is detected.

7. Corrective Actions: Specific corrective actions are implemented in accordance with the plant quality assurance (QA) program. For example, corrective actions are taken to prevent recurrence when the specified limits for fuel oil standards are exceeded or when water is drained during periodic surveillance. If accumulated water is found in a fuel oil storage tank, it is immediately removed. In addition, when the presence of biological activity is confirmed, a biocide is added to fuel oil. As discussed in the Appendix for GALL, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the corrective actions.

8. Confirmation Process: Site QA procedures, review and approval processes, and administrative controls are implemented in accordance with the requirements of 10 CFR Part 50, Appendix B. As discussed in the Appendix for GALL, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address the confirmation process and administrative controls.

9. Administrative Controls: The administrative controls for this program provide for a formal review and approval of corrective actions. The administrative controls for this program are implemented through the site's QA program in accordance with the requirements of 10 CFR Part 50, Appendix B

10. Operating Experience: The operating experience at some plants has included identification of water in the fuel, particulate contamination, and biological fouling. In addition, when a diesel fuel oil storage tank at one plant was cleaned and visually inspected, the inside of the tank was found to have unacceptable pitting corrosion (>50% of the wall thickness), which was repaired in accordance with American Petroleum Institute (API) 653 standard by welding patch plates over the affected area.

References

10 CFR Part 50, Appendix B, Quality Assurance Criteria for Nuclear Power Plants, Office of the Federal Register, National Archives and Records Administration, 2009.

API 653, Tank Inspection, Repair, Alteration, and Reconstruction, American Petroleum Institute, April 23, 2009.

ASTM D 0975-04, Standard Specification for Diesel Fuel Oils, American Society for Testing Materials, West Conshohocken, PA, 2004.

ASTM D 1796-97, Standard Test Method for Water and Sediment in Fuel Oils by the Centrifuge Method, American Society for Testing Materials, West Conshohocken, PA, 1997.

ASTM D 2276-00, Standard Test Method for Particulate Contaminant in Aviation Fuel by Line Sampling, American Society for Testing Materials, West Conshohocken, PA, 2000.

ASTM D 2709-96, Standard Test Method for Water and Sediment in Middle Distillate Fuels by Centrifuge, American Society for Testing Materials, West Conshohocken, PA, 1996.

ASTM D 4057-95, Standard Practice for Manual Sampling of Petroleum and Petroleum Products, American Society for Testing Materials, West Conshohocken, PA, 2000.

ASTM D 6217-98, Standard Test Method for Particulate Contamination in Middle Distillate Fuels by Laboratory Filtration, American Society for Testing Materials, West Conshohocken, PA, 1998.

US NRC Regulatory Guide 1.137, Rev. 1, Fuel-Oil Systems for Standby Diesel Generators, U.S. Nuclear Regulatory Commission, October 1979. Safety Evaluation Report Related to the License Renewal of Three Mile Island Nuclear Unit 1, Section 3.0.3.2.12, Fuel Oil Chemistry – Operating Experience, June 2009.

Microbiologically Influenced Corrosion - A degradation mechanism of corrosion influenced by microorganisms.

Quality Assurance

United States of America

Nuclear Regulatory Commission - The US federal government agency that regulates nuclear power plants