IR 05000271/2002003

IR 05000271-02-003, on 05/20-06/07/2002, Vermont Yankee Nuclear Power Station, Vermont Yankee Nuclear Power Corporation, Safety System Design and Capability Performance Inspection Report

ML022030454
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	07/22/2002
From:	Doerflein L Division of Reactor Safety I
To:	Balduzzi M Vermont Yankee
References
FOIA/PA-2005-0031 IR-02-003
Download: ML022030454 (14)

Text

July 22, 2002

SUBJECT:

VERMONT YANKEE - NRC INSPECTION REPORT 50-271/02-03

Dear Mr. Balduzzi:

On June 7, 2002, the NRC completed an inspection at the Vermont Yankee Nuclear Power Station. The enclosed report documents the inspection findings which were discussed on June 7, 2002, with Mr. Kevin Bronson and other members of your staff.

This inspection examined activities conducted under your license as they relate to safety system design and performance capability of the residual heat removal service water (RHRSW)

and automatic depressurization systems and compliance with the Commissions rules and regulations and with the conditions of your license. Within these areas, the inspection consisted of a selected examination of calculations, drawings, procedures and records, observations of activities and interviews with personnel.

Based on the results of this inspection, the team identified one finding of very low safety significance (Green) regarding the chemistry control program, which was not effective at minimizing the buildup of microbiologically influenced corrosion in the RHRSW and service water systems and has resulted in repeated RHRSW pump performance problems since 1999.

In accordance with 10 CFR 2.790 of the NRC's "Rules of Practice," a copy of this letter and its enclosure will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of NRC's document system (ADAMS). ADAMS is accessible from the NRC Web-site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/

Lawrence T. Doerflein, Chief Systems Branch Division of Reactor Safety Docket No.

50-271 License No.

DPR-28

Mr. Michael

Enclosure:

Inspection Report 50-271/02-03 Attachment:

Supplemental Information

REGION I==

Docket No.

50-271 Licensee No.

DPR-28 Report No.

50-271/02-03 Licensee:

Vermont Yankee Nuclear Power Corporation Facility:

Vermont Yankee Nuclear Power Station Location:

Vernon, Vermont Dates:

May 20 - 24 and June 3 - 7, 2002 Inspectors:

L. Prividy, Senior Reactor Inspector G. Cranston, Reactor Inspector K. Kolaczyk, Reactor Inspector A. Lohmeier, Reactor Inspector K. Mangan, Reactor Inspector R. Taylor, Reactor Intern, NRR R. Cooney, Contractor Approved by:

Lawrence T. Doerflein, Chief Systems Branch Division of Reactor Safety

ii SUMMARY OF FINDINGS IR 05000271/02-03, on 05/20-06/07/2002; Vermont Yankee Nuclear Power Station; Vermont Yankee Nuclear Power Corporation; Safety System Design and Capability Performance Inspection Report.

The inspection was conducted by five region-based inspectors and a contractor. One Green finding was identified. The significance of most findings is indicated by their color (Green, White, Yellow, Red) using IMC 0609 Significance Determination Process (SDP). Findings for which the SDP does not apply are indicated by No Color or by the severity level of the applicable violation. The NRC's program for overseeing the safe operation of commercial nuclear power reactors is described at its Reactor Oversight Process website at http://www.nrc.gov/reactors/operating/oversight.html A.

Inspector Identified Findings Mitigating Systems (Green) The inspectors found that the licensees chemistry control program was not effective at minimizing the buildup of microbiologically influenced corrosion (MIC) in the residual heat removal service water (RHRSW) and service water (SW) systems. Even though the licensee was chemically treating the RHRSW and SW systems to control biofouling, the performance of the RHRSW pumps had degraded on numerous occasions into the alert range during in service testing. Additionally, the SW and RHRSW piping has developed more than 20 documented pinhole leaks that were caused by MIC.

This finding was considered greater than minor since an ineffective chemistry control program could be reasonably viewed as a precursor to a significant event or, if left uncorrected, could become a more significant safety concern. However, the inspectors considered this issue to be of very low safety significance (Green) in accordance with Phase 1 of the mitigating systems SDP screening criteria because the ineffective chemistry control program has not rendered the RHRSW or SW system inoperable and because of RHRSW and SW system redundancy.

B.

Licensee Identified Findings None

Report Details 1.

REACTOR SAFETY Cornerstones: Initiating Events, Mitigating Systems, and Barrier Integrity 1R21 Safety System Design and Performance Capability (71111.21)

a.

Inspection Scope The team reviewed the design and performance capability of the residual heat removal service water (RHRSW) system, RHRSW system performance capability when operating in the alternate cooling system (ACS) mode, and the chemistry control program associated with the RHRSW and service water (SW) systems as related to known microbiologically influenced corrosion (MIC) problems. The team also reviewed the design and performance capability of the automatic depressurization system (ADS).

The RHRSW system, consisting of four pumps and two heat exchangers, provides a dynamic heat sink for the residual heat removal (RHR) system to achieve core and containment cooling during normal and accident conditions. The RHRSW system receives water from either the SW system or from the cooling tower deep basin when operating in the ACS mode should the SW pumps be unavailable. When the high pressure coolant injection system is unavailable, the ADS, consisting of four pneumatically operated relief valves (one on each main steam line), provides automatic nuclear system depressurization which allows the RHR and core spray systems to inject water and meet core cooling requirements.

The team verified that the system design bases were in accordance with the licensing commitments and regulatory requirements and that selected design documents, such as drawings and design calculations, were correct. The documents reviewed included system diagrams, engineering analyses, engineering department self assessments, surveillance tests, work orders, procedures (including emergency operating procedures), calculations, event reports, piping and instrumentation drawings (PI&D),

electrical schematics, and instrument setpoint documentation.

For selected calculations and analyses, the team reviewed the assumptions to verify that they were appropriate and agreed with current plant configurations, that proper engineering methods and models were used, and that there were adequate technical bases to support the conclusions. When appropriate, the team performed independent calculations to evaluate the document adequacy.

The team reviewed the capability of the ADS to perform its design function. Specifically, the team reviewed: the control of the safety relief valve solenoid-operated valves; the manual and automatic logic circuitry; the nitrogen accumulator capacity and testing; and the set pressure testing of the safety relief valves.

The team reviewed RHRSW system and ADS electrical single line diagrams, logic and elementary schematic and wiring diagrams to confirm the redundancy of the power supplies for pumps, valves, instrumentation and control equipment within the inspection scope. Additionally, the team evaluated the size and setting of over-current protective

devices to ensure that adequate power was provided to the systems and components reviewed and that their independence was maintained under faulted conditions.

Concerning the RHRSW system mechanical design, the team reviewed: (1) the capability to supply sufficient cooling water to the RHR and emergency diesel heat exchangers under design and transient conditions; (2) the structural integrity of the RHRSW pump suction barrels since chemical treatments and physical cleaning (scraping) of the internal barrel walls had also removed base metal; (3) the inspection results of the RHRSW heat exchangers for evidence of fouling from MIC or other debris; (4) the RHRSW pump performance curves from recent surveillance tests; (5) the adequacy of the net positive suction head (NPSH) for the RHRSW pumps when the system was operating in the ACS mode; and (6) the employment and effectiveness of a chemistry control program, since ongoing pump performance problems were primarily attributed to MIC. The chemistry control procedures used for monitoring and controlling MIC were reviewed.

The team also reviewed the current performance and test acceptance criteria for the RHRSW system and ADS to ensure consistency between allowable component performance and minimum allowable capabilities assumed in the accident analyses and associated design basis calculations. Preventive maintenance activities were reviewed to verify that maintenance was performed as scheduled using controlled procedures and that the system met its design basis function during the maintenance evolution. The team reviewed the implementation of the Maintenance Rule for the RHRSW system and ADS to verify proper identification and resolution of maintenance rule-related issues.

Additionally, the team evaluated a sample of surveillance and post-maintenance test results to confirm system capability. Available trend and performance reports and graphs, such as system health reports and in service testing (IST) data, were also reviewed to evaluate historical system performance and trends.

The team conducted a detailed walkdown of accessible portions of the selected and supporting systems to verify that the installed configuration will support the system functions under accident and abnormal event conditions, including safe shutdown of the plant with the control room inaccessible. The team also interviewed personnel responsible for certain aspects of system performance. Lastly, the team selected a sample of event reports associated with the selected systems and an additional sample of event reports issued by engineering (over the past year) to verify the licensee was identifying design issues at an appropriate threshold, entering them in the corrective action program, and taking appropriate corrective actions.

b.

Findings (Green). The team found that the licensees chemistry control program was not effective at minimizing the buildup of MIC in the RHRSW and SW systems. The finding was determined to be of very low safety significance (Green) because the ineffective chemistry control program has not rendered the RHRSW or SW system inoperable.

While chemistry control procedures existed, such as OP 4630, Rev. 4, Sampling and Treatment of the Service Water System, the chemistry control program for the RHRSW and SW systems lacked clear goals for eliminating the MIC that was causing pinhole leaks, preventing further MIC growth, or removing MIC growth from the piping. The licensee had implemented a chemistry control program for the RHRSW and SW systems as a corrective action for a number of MIC and/or corrosion related component degradations. However, the team found that the existing program did not address the requirements for inspections to determine the extent of the MIC problem, chemical addition requirements, and trending to assess effectiveness.

Several examples illustrated the weak performance of the chemistry control program.

Even though the RHRSW and SW systems were being chemically treated to control biofouling, the performance of the RHRSW pumps had degraded on numerous occasions into the alert range during inservice testing, caused by fouling of the pump suction barrel (worst degradation in the D pump) and the piping due to MIC. This has resulted in increased pipe losses and flow turbulence at the suction of the pump, causing reduced impeller efficiencies. Additionally, the SW and RHRSW piping had developed more than 20 documented pinhole leaks that were caused by MIC. Other observations regarding the weak performance of the chemistry control program were as follows:

The team noted that the SW sample line was out of service due to a potential MIC induced leak. Since sampling could not be done, chlorine was not being added to the SW system. Though the sample line had been removed from service for a month and was not scheduled to be repaired and returned to service for several more weeks, the impact of not adding chlorine had not been evaluated.

• The team observed that the licensees practices concerning piping and component visual inspection and sampling for MIC were random, they did not take into account where MIC was most susceptible, and they were limited to observing the internals of valves and pumps (including adjacent, visible pipe walls) during maintenance.

This issue was considered greater than minor since an ineffective chemistry control program could be reasonably viewed as a precursor to a significant event or, if left uncorrected, could become a more significant safety concern. In this regard, the team was concerned about the recurrence of a heat exchanger macrofouling event similar to a past event, as documented in SYSENG 97-123 Memorandum (September 23, 1997),

for which the root cause was not determined. Twenty tubes (almost 5%) of the scavenging air cooler for the B emergency diesel generator were completely plugged with tubercles formed by MIC which apparently broke loose from the piping during this past event. The team confirmed that no such events have occurred since 1997.

Nonetheless, the team considered this issue to be of very low safety significance (Green) in accordance with Phase 1 of the mitigating systems Significance Determination Process screening criteria because the ineffective chemistry control program has not rendered the RHRSW or SW system inoperable and because of RHRSW and SW system redundancy. No violation of regulatory requirements occurred.

The licensee responded to the teams finding on the chemistry control program by stating at the exit meeting that this issue was a significant concern with their senior management, especially going forward in their long range planning for plant power uprate and life extension processes. The chemistry control program issue was being added to the plant Key Issues List which includes issues that receive ongoing, focused attention every 2 weeks with the plant manager as part of the licensees corrective action program. The licensee entered this issue in its corrective action program as ER 2002-1412. (FIN 50-271/02-03-01)

4.

OTHER ACTIVITIES (OA)

4OA6 Meetings, Including Exit Management Meeting The team presented the inspection results to Mr. Kevin Bronson and other members of the licensees staff at an exit meeting on June 7, 2002. In addition, the team discussed the final characterization of the Green finding with Messrs. G. Wierzbowski and J.

Callaghan in a telephone conversation on July 17, 2002. The team verified that the inspection report does not contain proprietary information.

ATTACHMENT 1 SUPPLEMENTARY INFORMATION a.

Key Points of Contact Vermont Yankee Nuclear Power Corporation H. Breite System Engineer K. Bronson Plant Manager J. Callaghan Lead Design Engineer, Fluid Systems P. Corbett Maintenance Superintendent J. DeVincentis Licensing Engineer J. Dreyfuss Acting Director, Engineering C. Edwards Fluid Systems Engineer J. Garozzo Electrical and I&C Engineer R. Gerdus Plant Chemist E. Harms Assistant Operations Superintendent J. Hoffman Superintendent, Design Engineering R. January Lead Design Engineer, Electrical and I&C D. Jeffries System Engineer S. Jonasch System Engineer P. Johnson Design Engineer, Electrical and I&C M. Metell Design Engineer, Fluid Systems P. Rainey Contractor J. Stasolla System Engineer J. Thayer Entergy R. Wanczyk Director, Safety and Regulatory Affairs S. Wender Chemistry Manager G. Wierzbowski Acting Superintendent, System Engineering D. Yasi Contractor b.

List of Items Opened, Closed and Discussed Opened and Closed FIN 50-271/02-03-01 Ineffective chemistry control program for RHRSW and SW systems.

c.

Documents Reviewed CALCULATIONS, ANALYSES, and REPORTS VYC-125 Ventilation Changes for Diesel and HVAC Equipment Room, Rev. 2 VYC-684 RHR Service Water Pump Full Flow Test Acceptance Values VYC-686H Service Water Header-Low Pressure Isolation Uncertainty & Setpoint-PS 104 120A/B/C/D, Rev. 0 VYC-714A Set Point and Uncertainty Calculation, ADS Actuation Time Delay Relay, Rev. 0

VYC-722B Residual Heat Removal Service Water System Flow Instrument Loop Accuracy Evaluation, Rev. 1 VYC-730 125 VDC Battery AS-2, Rev. 2 VYC-830 Voltage Drop Calculation for DC Distribution Panels DC-1 & DC-2, Rev. 9 VYC-886 Station Blackout Analysis VYC-1088 VY 4160/480 Volt Short Circuit and Voltage Drop Study, Rev. 2 VYC-1096 Hydrogen Generation for Main Station Batteries, Rev. 1 VYC-1188 125 VDC Relay and Circuit Breaker Coordination, dated October 5, 1999 VYC-1240 Alternate Cooling Pressure Loss Analysis VYC-1279 Determine Maximum Allowable RHRSW Pump Degradation and Maximum Cooling Tower Flows, Rev. 4 VYC-1284 Service Water to Emergency Diesel Generator, Flow Indicator Loop Accuracy Review, Rev. 0 VYC-1290 Vermont Yankee Post-LOCA Torus Temperature and RHR Heat Exchanger Evaluation VYC-1349 125 VDC Control Voltage Drop Study, Battery A-1 and B-1, Rev. 2 VYC-1604 Drift Calculation for ADS Time Delay Relay, Rev. 0 VYC-1803A Thermal Performance of Alternate Cooling System Using Cooling Tower Test Data, Rev. 2 VYC-2045 Residual Heat Removal Heat Exchangers Fouling Factors and Projected Heat Rates for Cycle 21, dated December 1, 1999 VYC-2053 Residual Heat Removal Heat Exchangers E-14-1A and E-14-1B Thermal Performance Test Data Evaluation and Uncertainty Analysis, Rev. 0 VYC-2086 Service Water System Hydraulic Model Trending Analysis, Rev. 1 VYC-2153 125 VDC Battery A-1 Electrical System, Rev. 0 VYC-2154 125 VDC Battery B-1 Electrical System, Rev. 0 PGT-98-1118 Validation of PROTO-HX Version 3.00 Model Inputs for the VY Nuclear Plant RHR Heat Exchangers E-14-1 A(B)

PROCEDURES OP 2124 Residual Heat Removal System, Rev. 49 OP 2181 Service Water/Alternate Cooling Operating Procedure, Rev. 52 OP 3126 Shutdown using Alternate Shutdown Methods, Rev. 16 OP 4122 Automatic Blowdown System Surveillance, Rev. 20 OP 4124 Residual Heat Removal and RHR Service Water System Surveillance, Rev. 54 OP 4126 Diesel Generators Surveillance, Rev. 46 OP 4181 Service Water/Alternate Cooling System Surveillance, Rev. 33 OP 4192 HVAC Surveillance, Rev. 13 OP 4210 Maintenance and Surveillance of Lead Acid Batteries, Rev 30 OP 4215 Main Station Battery Performance/Service Test, Rev. 11 OP 4216 Main Steam Safety Relief Valve Discharge Line Vacuum Breaker Testing OP 4343 ADS System Logic Test, Rev. 21 OP 4345 Automatic Depressurization System Power Monitor Functional Test, Rev.

OP 4630 Sampling and Treatment of the Service Water System, Rev. 4 OP 4655 Chemical Soak Treatment of the RHRSW Pumps, Rev. 1

OP 5202 Maintenance/Inspection of Safety Related Heat Exchangers, Pressure Vessels and Tanks, Rev. 13 OP 5265 Service Water Component Inspection and Acceptance Criteria, Rev. 4 PP 7204 Safety & Relief Valve Program, Rev. 2 PP 7601 Service Water Chemical Treatment and Monitoring Program NE 8046 Visual Examination Procedure for VT-2, Rev. 1 PP 7007 Vermont Yankee Setpoint Program STP 98-003 VY RHR Heat Exchanger Thermal Performance Procedure and Evaluation, dated April 1998 STP 95-02 Hydraulic Performance Testing of the Alternate Cooling System, dated September 1995 DRAWINGS H-82215 SWECO Residual Heat Exchanger General Arrangement Sectional Assembly 5920-FS-I12B Service Water Piping in Reactor Building G-200357 Circulating Water System Cooling Tower Number 2-Foundation 5920-10449 ISI Pressure Test Diagram - Service Water 5920-12712 RHRSW Pump Curve G-191299 4KV Auxiliary One Line Diagram, Rev. 23 G-199300 480 Volt Auxiliary One Line Diagram, Switchgear Bus8, MCC8A,8C, sh1, Rev. 17 G-199300 480 Volt Auxiliary One Line Diagram MCC8B,8E,89B, sh2, Rev. 21 G-199301 480 Volt Auxiliary One Line Diagram, Switchgear Bus9,MCC 9A,9C, sh1, Rev. 17 G-199301 480 Volt Auxiliary One Line Diagram MCC 9B,9D,89A, sh2, Rev. 17 G-191372 125V DC One Line Diagram, sh 1, Rev. 60 G-191372 125V DC One Line Diagram, sh2, Rev. 21 G-191372 125V DC One Line Diagram, sh3, Rev. 21 B-191301 4KV Auxiliary Relay Circuit, sh317, Rev. 9 B-191301 Station Service Water Pumps P7-1A,1B,1C,1D, sh423,424,425A,426,427, Rev. 7 B-191301 Auto Blowdown System Logic A, sh750, Rev. 12 B-191301 Auto Blowdown System Logic B, sh751, Rev. 17 B-191301 Auto Blowdown System RV2-71A, sh752, Rev. 15 B-191301 Auto Blowdown System RV2-71B, sh753, Rev. 16 B-191301 Auto Blowdown System RV2-71C, sh754, Rev. 9 B-191301 Auto Blowdown System RV2-71D, sh755, Rev. 11 B-191301 Auto Blowdown System Temperature Display, sh756, Rev. 12 B-191301 SRV Position Indication, sh756A, Rev. 7 B-191301 RHRSW Discharge Valve V10-89B, sh1286, Rev. 14 B-191301 RHRSW Discharge Valve V10-89A, sh1287, Rev. 15 B-191301 RHRSW Pump P8-1A,P8-1B,P8-1C,P8-1D, sh1304,1305,1306,1307, Rev. 15 EVENT REPORTS

19960007, 19960707, 19970504, 19981696, 19982007, 19982029, 19982048, 19982223, 19982224, 19990025, 20000427, 19990025, 19990205, 20000427, 20000825, 20000844, 20000956, 20001200, 20001064, 20001113, 20001197, 20001282, 20001828, 20010021, 20010032, 20010913, 20011023, 20011066, 20011116, 20011173, 20011437, 20011468, 20011512, 20011572, 20011658, 20011680, 20011751, 20011897, 20011971, 20012125, 20012151, 20012225, 20012230, 20011663, 20011971, 20012074, 20012225, 20012230, 20012299, 20012413, 20012588, 20020083, 20020168, 20020329, 20020347, 20020480, 20020583, 20020637, 20020663, 20020698, 20020760, 20020765, 20020806, 20020815, 20020828, 20020852, 20020857, 20020875, 20020925, 20020945, 20021025, 20021107, 20021153, 20021185, 20021192, 20021223, 20021323, 20021351, 20022230 WORK ORDERS WO949153, WO 960900, WO 975818, WO 987256, WO 004672, WO 004943, 00-001039-010, 00-001935-000, 00-001943-000, 00-004554-000, 00-007021-001, 00-007021-002, 00-007021-003, 00-007021-004, 01-002576-000, 01-002894-000, 01-004572-000, 02-000472-000, 02-000473-000, 02-000474-000, 02-000475-000, 02-000476-000, 02-000477-000 MODIFICATIONS MM 2002-001 Replacement of RRU-8 Cooling Coil MM 2002-022 B RHRSW Subsystem Motor Bearing Cooling Line Modification EDCR 93-403 Diesel Generator Service Water Piping Modification VYDC 2000-028 Main Station Battery Cell Replacement VYDC 2000-029 Battery Charger Modification SAFETY EVALUATIONS SE-2001-003 Cross-tie between Alternate Cooling and SFPC System SE-98-055 50.59 (a)(2) Safety Evaluation for BMO 98-44, Rev. 2 2000-022 50.59 Screening of B RHRSW Subsystem Motor Bearing Cooling Line Modification, Rev. 0 98-013 50.59(a)(2) Safety Evaluation for STP 98-003, dated March 18, 1998 OPERABILITY EVALUATIONS BMO 98-24R ADS Solenoid Operated Pilot Valve BMO 98-44 Significant Degradation of RHRSW Pumps Hydraulic Performance BMO 2002-06 RHRSW Pump Motor Operation with Potentially DegradedCooling, Rev. 0 NEDE Analysis of Generic BWR Safety/Relief Valve Operability Test 24988-P Results DESIGN BASIS DOCUMENTS Automatic Depressurization System, dated April 3, 1998 125 VDC System, dated December 7, 1999

Main Steam System, dated January 22, 1999 Service Water Systems - Service Water, Residual Heat Removal Service Water, and Alternate Cooling Systems, dated November 17, 1997 MISCELLANEOUS DOCUMENTS GL 89-04 Guidance on Developing Acceptable Inservice Testing Programs GL 89-13 Service Water System Problems Affecting Safety-Related Equipment IN 85-30 Microbiologically Induced Corrosion of Containment Service Water System IN 86-96 Heat Exchanger Fouling Can Cause Inadequate Operability of Service Water Systems IN 94-03 Deficiencies Identified During Service Water System Operational Performance Inspections LER 93-14 Inoperable Alternate Cooling System due to Inadequate Inspection/Acceptance Criteria LER-97-012 Residual Heat Removal Service Water Flow Could be Less than the Design Basis Flow due to Instrument Inaccuracies LER 99-001 Inadequate Communication Between Licensee and Equipment Manufacturer Results in the Incorrect Application of a Manufacturer Supplied Pump Curve and an Unanalyzed Condition NUREG-1482 Guidance for In service Testing at Nuclear Power Plants BVY 90-007 Response to Generic Letter 89-13, Letter dated January 22, 1990 BVY 91-46 NRC Response to Second VY Response to GL 89-13, Letter dated March 4, 1991 Self-Assessment Report, Service Water Operational Performance Inspection, dated March 11, 1994 NMRC 93-01 NEI Industry Guideline of Monitoring The Effectiveness of Maintenance at Nuclear Power Plants, Rev. 2 SMRC 2001-042 RHRSW Pump Suction Can Replacement, Evaluation of Options for Improving RHRSW Pump Performance, dated October 25, 2001 QDR-35.3 ASCO 3 Way Solenoid Valve, Rev. 3 Photographs of MIC Corroded Pump Blading and Suction Barrels, dated June 3-6, 2002 Residual Heat Removal Heat Exchanger Specification Sheet VYS-027 Separation Criteria for Reactor Protection, Engineered Safety Feature and Auxiliary Support Systems, Rev. 1 VYS-040 Guidelines for Protection and Coordination of Electrical Systems, Rev1 WS 1040 Equivalency Evaluation, ASCO Solenoid Valve, Rev. 0 Mapping of UT Wall Thicknesses of Pump Suction Barrel for RHRSW Pump 1A d.

List of Acronyms ACS Alternate Cooling System ADS Automatic Depressurization System BMO Basis for Maintaining Operability ER Event Report GL Generic Letter IN Information Notice ISI In service Inspection

IST In service Testing MIC Microbiologically Influenced Corrosion NPSH Net Positive Suction Head NRC Nuclear Regulatory Commission RHR Residual Heat Removal RHRSW Residual Heat Removal Service Water SDP Significance Determination Process SFPC Spent Fuel Pool Cooling STP Special Test Procedure SW Service Water WO Work Order