ML20239A075

Expanded Augmented Sys Review & Test Program (Expanded Asrtp) Evaluation of Main Feedwater Sys

ML20239A075
Person / Time
Site:	Rancho Seco
Issue date:	08/27/1987
From:	Croley B, Humenansky D, Stock F SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:
Shared Package
ML20238F564	List: ML20238F561 ML20239A030 ML20239A034 ML20239A038 ML20239A043 ML20239A046 ML20239A053 ML20239A066 ML20239A075 ML20239A082 ML20239A084 ML20239A089 ML20239A104 ML20239A107
References
NUDOCS 8709170063
Download: ML20239A075 (23)

Text

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EXPANDED AUGMENTED SYSTEM REVIEH AND TEST PROGRAM (EXPANDED ASRTP)

EVALUATION OF THE MAIN FEEDHATER SYSTEM SUBMITTED BY: / 2av 2I DATE: Ncf 2fI28 '7 FRANK STOCK TEAM LEADER CONCURRENCE: If%< $  %! wi w ki ) DATE: 1 2 f n tl AVID HUMENANSKY ')

'[EXPMIDED ASRTP PROGRAM AGER M CONCURRENCE:

sb v' L# DATE: V/27

/

7 BCB CROLEY DIRECTOR, NUCLEAR TECHNICAL SERVICES B709170063 870909 PDR ADOCK 05000312 o PDR c_-________________-_-_-_______________ _ _ _

IABLE OF CONTENTS P3ae Number

1.0 INTRODUCTION

3 2.0 PURPOSE 4 3.0 SCOPE 5 q l

4.0 OVERALL RESULTS AND CONCLUSIONS 6 l

5.0 SPECIFIC CONCERNS 8 5.1 Acknowledged (Valid) Concerns 5.2 Open (Potential) Concerns 6.0 ATTACHMENTS 9 6.1 List of Documents Reviewed 10 6.2 Status of RIs 15 6.3 Detailed Observations - Requests for Information 16 l

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EXPANDED AUGMENTED SYSTEM REVIEH AND TEST PROGRAM EVALUATION OF THE MAIN FEEDHATER SYSTEM ,

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1.0 INTRODUCTION

The Rancho Seco Expanded Augmented System Review and Test Program (ASRTP) evaluation effort involves an assessment of the effectiveness of the System Review and Test Program [SRTP] and an analysis of the adequacy of ongoing programs to ensure that systems will continue to function properly after restart. The Expanded ASRTP is a detailed system by system review of the SRTP as implemented on 33 selected systems and an in-depth review of the engineering, modification, maintenance, operations, surveillance, inservice testing, and quality programs. It also conducts a review, on a sampling basis, of many of the numerous ongoing verification and review programs at Rancho Seco. j i

Six multi-disciplined teams composed of knowledgeable and i experier.:ed personnel are tasked with performing the Expanded l ASRTP. Each multi-disciplined team consists of dedicated personnel with appropriate backgrounds to evaluate the operation ,

maintenance, engineering, and design functionni areas.

Independence, perspective, and industry standards provided by team members with consultants, architect engineer ar.1 vendor backgrounds are joined with the specific plant knowledge of SMUD team members.

Each team performs an evaluation on a selectea system using the same fundamental evaluation techniques employed by the NRC in the ASRTP ,

inspection. System Status Reports are used as the primary source of i leads for the teams. They are augmented with references to available source and design bases cocuments as needed. Team synergism and communication is emphasized during the process in  !

order to enhance the evaluation. Each team prepares a report for j each completed selected system evaluated. This report is for the '

main feedwater system.

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l 2.0 PURPOSE l

The objectives of the Expanded ASRTP evaluation are to (1) assess the adequacy of activities and systems in support of restart and (2) evaluate the effectiveness of established programs for ensuring j safety during plant operation after restart.

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3.0 SCOPE

. To accomplish the first objective, the steam plant team evaluated the main feedwater system to determine whether:

1. The system was capable of performing the safety functions required by its design bases.

2. Testing was adequate to demonstrate that the system would perform all of the safety functions required.

3. System maintenance (with emphasis on pumps and valus) was adequate to ensure system operability under postulated accident conditions.

4. Operator and maintenance technician training was adequate to ensure proper operations and maintenan.ce of the system.

5. Human factors relative to the system and the system's supporting procedures were adequate to ensure proper system operations under normal and accident conditions.

To accomplish the second objective, the team reviewed the programs as implemented for the system in the following functional areas:

1. Systems Ce3i q and Change Control

2. Maintenance

3. Operations and Training

4. Surveillance and Inservice Testing

5. Quality Assurance

6. Engineering Programs The team reviewed a number of documents in preparation for and during the Expanded ASRTP evaluation. This list of documents is found in Attachment 6.1.

The primary source of leads for the team were the problems identified in the Main feedwater System Status Report. Various source documents such as the USAR and Technical Specifications and available design bases documents were reviewed as needed to augment the information needed by the team.

The evaluation of the main feedwater system included a review of pertinent pcrtions of support systems that must be functional in order for the main feedwater system to meet its design objectives.

4.0 OVERALL RESULTS AND CONCLUSIQ15 The more significant issues identified pertaining to the adequacy of the SRTP and the effectiveness of programs to ensure continued safe i operations after restart are summarized below. The summary focuses on the weaknesses identified during the evaluation. Attachment 6.3 provides detailed findings by providing the Request for Information I (RI) forms that are used by the Expanded ASRTP teams to identify l potential concerns during the evaluation. Section 5.0 lists the specific concerns identified by the teams. The numbers in brackets after each individual summary or concern refer to the corresponding RIs in Attachment 6.3.

1 4.1 Design Engineering I 4.1.1 The first and second point feedwater heater tube sides may '

be overpressurized.by the main feedwater pumps as a result of the design pressures of the feedwater heater tube sides being less than the MFH pump high discharge pressure ,

setpoint trip, the time delay setpoint', and the alarm )

setpoint.

Additionally, the relief valves on the tube sides are sized such that the possibility of overwhelming the relief valves due to the flow capabilities of the main feedwater pumps exists. There is also a lack of a documented bases for the various setpoints referenced above.

The discrepancies noted in system design pressures and related component setpoints may lead to equipment operation that exceeds design limits in the main feedwater system.

[RI 108) [RI 112]

4.2 System Maintenance and Operation 4.2.1 High pressure feedwater heaters IB end 2A have an excessive l number of tubes plugged in the drains cooler area of the l heaters. For the heaters referenced, the number of tubes l plugged represents approximately 13.2% and 23%, respectively, l l

of the total number of tubes in the heaters, i

l The effect of these plugged tubes is the amount of cooling for the condensate is reduced, the temperature of the drain water to the suction of the heater drain pumps increases, and the NPSH to the drains pumps decreases.

This may result in excessive tripping of the pumps and may be a major cause of the continuing heater drain pump trips which ensued during the summer of 1985.

E---------_------_______------__--_-__--______---

OVERALL RESULTS ANE CONCLUSIONS (Continued)

The impact of this excessive pump tripping may result in shocks to the HFH system and to the condensate r"mp, problems with packing of resin beds, and adverse flowrates.

The excessive tube plugging results in an increase in flow through existing tubes, a reduction of heat transfer to feedwater, and a reduction in feedwater heater efficiency.

[RI 127]

4.2.2 Long term lay-up of the HFH system has not been maintained in order to protect system piping and components from damaging corrosion. The main feedwater system has been isolated from the condensate system and has not been circulated.

There is no detailed inspection and test program planned for the tystem prior to restart. Although leng cycle clean up will identify some problems within the system, all potential problems may not become evident until the unit is returned to service. [RI 085) l l

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5.0 SPECIFIC CONCERNS A list of the specific concerns the Expanded ASRTP team believes are new concerns not previously identified for resolution follows:

5.1 Acknowledged (Valid) Concerns 1 I

5.1.1 Excessive tripping of the heater drain pumps may occur due to excessive plugging in the drain cooler area of high pressure feedwater heaters 18 and 2A. [RI 127]

5.1.2 The design pressure of the first and second point feedwater heater tube sides is less than the main feed pumps' high pressure alarm and setpoints. [RI 108] 1 5.1.3 Long term lay-up of the MFW system has not been maintained I in order to protect system piping and components. I Additionally, there is no detailed inspection and test '

program planned for this aspect of the system prior to restart. [RI 085]

1 5.1.4 The bases for the main feedwater pump high discharge i pressure trip, time delay trip and alarm setpoints are not '

defined. [RI 112) 5.2 Open (Potential) Concerns None i

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1 6.0 ATTACHMENTS 6.1 List of Documents Reviewed 6.2 Status of RIs 6.3 Detailed Observations - Requests for Information l

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LIST OF DOCUMENTS REVIEWED Procedures Maintenance and Calibration Procedures I.011 General Calibration Procedure I.012 Pneumatic Valve Stroking H.103 Valve Inspection and Maintenance Operating Procedures A.39 Auxiliary Steam System A.47 Condensate and Feedwater System A.50 Main Feedwater Pumps System A.51 Auxiliary Feedwater System A.53 Extraction Steam, Reheater /Feedwater Drains System B.2 Plant Heat-up and Start-up B.3 Normal Operations B.4 Plant Shutdown Annunciator Procedures H2YSA Turbine and Secondary System Panel A H2YSB Turbine and Secondary System Panel B Casuaity Procedures C.1 Load Rejection l

C.10 Loss of Steam Generator Feed or Steam Generator Overfeed C.26 Loss of Condenser Vacuum ATTACHMENT 6.1

1 LIST OF DOCUMENTS REVIEWED Process Standards AP.150 Main and Auxiliary Turbine System l AP.151 OTSG Secondary Side AP.152 Feedwater and Condensate System AP.153 Auxiliary Steam System AP.157 Turbine Lube Oil System Surveillance and Special Test Procedures l SP.210.04 Feedwater Trip on Steam Line Rupture Surveillance Test l SP.210.05 Turbine Mechanical Overspeed Trip Surveillance Test SP.210.06 Weekly Inspection of Selected Steam and Feedwater Piping Welds Main Boiler Feed Pump A Overspeed Test  !

SP.210.09A SP.210.098 Main Boiler Feed Pump B Overspeed Test STP.1020 Main Feed Pump (MFP) Protection Test (Draft)

RT-HFH.006 Variable Frequency Main Feed Pt,mp (HFP) Performance (Draft) Test RT-HFN.007 Biannual "A" Main Feed Pump (MFP) Turbine Overspeed (Draft) Test RT-HFH.008 Biannual "B" Main Feed Pump (HFP) Turbine Overspeed (Draft) Test Emergency Operating Procedures E.0.2 Vital System Status Verification ,

E.0.3 Loss of Subcooling l E.0.5 Excessive Heat Transfer  !

NEP-5305.78C Installation of Instrumentation, Instrumentation Racks and Panels I

ATTACHMENT 6.1 i

LIST OF DOCUMENTS REVIEWED Non-Conformance Reoorts:

4077, 4078, 5119, 5187, 5223, 5871, 6248, 6348, 6465, 6524, 6529, 6713, 6714, 6775, 5744, 5818 yendor Instruction Manuals:

IM 7991, M5.02-12, H5-03-57, M6.01-07, N28.02-308 Letters:

CCF 87-186, RIM 87-065 Operational Assessments OA 83-06 Drawinas:

E107 Rev 22 E108 Sh 12 Rev 13 E201 Sh 31 Rev 13 and 14 E201 Sh 32 Rev 8 E201 Sh 33 Rev 7 E201 Sh 34 Rev 6 E201 Sh 35 Rev 9 E201 Sh 31A Rev 3 and 4 E201 Sh 32A Rev 1 E201 Sh 33A Rev 0 l E201 Sh 34A Rev 0 E319 Sh 2 Rev 6 E319 Sh 4 Rev 7 E342 Sh 12 Rev 23 l M5.03-68 Sh 1 Rev 0 I H5.03-68 Sh 2 Rev 1 I M5.03-68 Sh 2A Rev 0 H22.05-10 H502.1-1 H-520 Sh 3 Rev 18 M-532 Sh 1 Rev 10 M-532 Sh 2 Rev 6 M-533 Sh 1 Rev 15  !

M-533 Sh 2 Rev 12  !

M-533 Sh 4 Rev 11 H-533 Sb 5 Rev 13 M-534 Rev 18 32170-2-03 32273-2-0B l l l ,

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LIST OF 00CUMENTS REVIEWED EX1 R-1607, R-0277, R-0717, R-1496, A-5572, A-3168, A-5415, R-0823 Abnormal Taqi:

3897, 3724, 3860, 3898, 3725, 3616, 3617 B&W Documents:

51-1164188-01, 47-1159449-00, 47-1163743-10 Calculation:

i Z-FWS-M1778 IE Notices:

84-87, 86-01 PH Tasks:

04800, 01490, 71155, 04904 Lesson Plans:

0024C-2300, RS-0024C-0713, RS-0024C-0716, OD211-4100, 0023J-1900, 0023J-2000, 0023C-1201, 0023C-1100 System Training Manual - Chapters 22A and 22B Operator Reading Assignment 86-11 Work Recuests:

000979, 001202, 001744, 002045, 002386, 003639, 004774, 004775, 006465, 010824, 011587, 012873, 013041, 049181, 060052, 060812 067515, 068875, 069655, 078028, 085429, 090443, 090920, 093352, 093353, 093372, 093376, 093377, 093379, 093383, 093388, 093389, 093390, 098462, 098561, 099210, 099585, 100095, 100096, 100098, 100134, 104624, 105900, 105901, 105908, 107228, 107707, 107838, 107839, 108580, 108861, 109399, 109745, 109943, 114582, 114916, 116659, 116677, 116690, 119528, 119535, 120408, 120409, 120796,

, 121720, 122771, 122909, 124902, 125374, 125590, 125593, 125595, 125956, 125597, 125599, 125600, 125601, 125602, 125635, 127587, 127588, 127589, 127754, 127852, 127853, 129133, 129135, 129250, 130186, 130887, 130890, 130893, 131431, 132448, 133188, 133424, 133550, 133919, 134827, 134828, 135112, 135327, 135522 ATTACHMENT 6,1 l

LIST OF DOCUMENTS REVIEWED Other Sources Reviewed:

TAP Reports Nucleis HIMS HEL Equipment History for MFW System Daily Work Plan Meeting Planning A3.2 Report USAR ,

l Technical Specifications ASME Section XI ASME Section VIII 4 1

Maintenance Training Course Listing B&WOG 1154 Report Bechtel Design Bases Document i

l NEPH 5472 SMUD System Design Bases Manual ANSI B31.1 l

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i ATTACHMENT 6.1 1

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STATUS OF RIs Attachment 6.2 provides RI status as of this report date. An RI is considered closed if the Team Leader was convinced ~ a potential concern was not valid or not significant enough to be an RI. An RI would also be closed if requested information was provided. All other RIs dre open.

Acknowledged RIs are open RIs that have been accepted as valid by the responsible organization and have been stated as concerns in Section 5.0.

RI NUMBER STATUS 085 Acknowledged 108 Acknowledged 112 Acknowledged 127 Acknowledged l

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ATTACHMENT 6.2 1

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DETAILED OBSERVATIONS - REOUEST FOR INFORMATION During an evaluation, all potential concerns are documented on Request for Information sheets (RIs) that are sent to the responsible  ;

organization to receive their input concerning the potential concern.  !

RIs are also used to reques t information that the EASRTP team is having difficulty obtaining.

These RIs are considered drafts throughout the entire evaluation until they become part of the report. Responsible organizations can accept the potential concern as valid or they may disagree with the potential concern. If they disagree, they can submit information that convinces the EASRTP team members that the potential concern is not valid, or they may redirect the EASRTP members to better focus the concern. RIs developed during the system evaluation comprise this section of the report.

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ATTACHMENT 6.3

l REQUEST FOR INFORMATION (RI)

RI NO: 085 SYSTEM CODE: McH ISSUE DATE: 8-10-87

SUBJECT:

LONG TERM LAY-UP OF SYSTEM COMPONENTS DEPARTMEr4T: OPERATIONS COORDINATOR / EXT: R. MACIAS/4153 TEAM LEADER / EXT: F. STOCK /3929 CONCERN Long term lay-up of the HFW system has not been maintained in order to protect system piping and components from damaging corrosion. At present there is no detailed inspection and test program planned prior to restart.

REVIEW /RESULTS Due to an inconsistent program for maintaining the nitrogen blanket and I wet lay-up conditions for the MFW piping and components, a corrosion problem may have developeo to the extent of impacting system integrity.

l Although long cycle clean-up will identify some problems within the system, all potential problems may not become evident until the unit is )

returned to cervice.

Investigation into this concern has found the following information:

1) Operations personnel have stated that the feedwater side of the heaters was put into wet lay-up, and the shell side of the heaters was charged with a nitrogen blanket.

2) They also stated that shortly after the nitrogen blanket was i initiated, the I&C Department removed the nitrogen regulator for l repair and did not replace the regulator for approximately 5 l

month; During this period, no nitrogen protection was on the heat. 3.

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3) Discussions with Maintenance and Systems Engineering has found that long term lay-up has been "On again - off again" for the total period of the outage.

4) Both the Chemistry Department and Operations Department have stated l that MFH system has been isolated from the Condensate System, and I

has not been circulated nor gone through clean-up for an extended period of time. This appears to be the only system in the plant that has not been operated during the full period of the outage.

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RI NO: QEi (Continued)

5) Chemistry personnel have stated that chemical testing of the wet lay-up water has not been performed, so that the present condition of the water (;5, chemical levels, etc.) is unknown.

6) Chemistry personnel and operations personnel have stated that the Work Planning Group did not appear to use Long Term Lay-up of the system as a consideration when scheduling maintenance.

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REQUEST FOR INFORMATION (RI)

RI N0: 108 SYSTEM CODE: HFW ISSUE LATE: 8-5-87 ,

SUBJECT:

OVERPRESSURIZATION OF THE FIRST AND SECONO CINT HEATERS i DEPARTMENT: DESIGN ENGINEERING COORDINATOR / EXT: TOM TELFORD/3849 TEAM LEADER / EXT: FRANK STOCK /3929 I CONCERN I J

The first and second point feedwater heater tube sides can be over-pressurized by the main feedwater pumps. The design pressure of the  ;

feedwater heater tube sides is below the main feed pumps high pressure J alarm and trip setpoints. Therefore, feedwater heater operation in i excess of design pres ure may result, causing possible tube bundle failure.

REVIEW /RESULTS j l

The design pressure f the first and second point feedwater heater tube { '

sides is 1500 psig. rhe relief valves PSV-32221 (A side) and PSV-32222 (B side) on the second point heater tube sides are set for 1500 e 15 psig. PSV-32221 is sized for 7347 lbs/hr saturated steam and PSV-32222 i is sized for 4995 lbs/hr saturated steam. The poss'~'lity of  !

overwhelming the relief valves due to the flow capabilities of the main feedwater pumps exists. Exceeding the relief valve capacity could cause pressure to increase above design pressure (1500 psig).

The main feed pumps high high pressure trip setpoint is 1650 e 10 psig. The time delay trip setpoint is 1575 = 5 psig and the alarm setpoint is 1545 e 10 psig. Sufficient information for the referenced setpoint bases is unavailable. See RI 112 for details on setpoint bases.

Therefore, the possibility of operating the main feedwater pumps at greater than 1500 psig without receiving an alarm or pump trip exists.

This results in operation of the main feedwater pumps discharge pressure exceeding the design pretsure of the tube sides of the first and second point heaters.

Possible consequences of overpressurizing the tube side of the feedwater i heater include:

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1) Tube stress and possible tube rupture or failure

2) Potential release or contaminated feedwater to the turbine building drain system via t m relief valve discharge.

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RI NO: 103 (Continued)

3) Overpressurizirg the shell side of the feedwater heater, resulting in lifting the shell side relief valve and possibly overflowing the blowdown tank. A potential release of contaminated water may occur i from overflowing the blowdown tank. I i

4) The tube side relief valve lifting and expcsing personnel to a safety hazard due to hot condensate and steam in the relief line at j the scupper drain. j

5) Feedwater and turbine transients caused by isolation of extraction steam to the affected heater resulting from a high level in the j feedwater heater. Isolation of extraction steam to a feedwater j heater can result in a change in feedwater temperature and turbine l load.

REFERENCES i 1) M6.Ji-07, Westinghouse Instruction Book for Feedwater Heaters l 2) Process Standard AP.152, Rev. 20 4

3) Westinghouse Feedwater Heater Name Plate Data j

4) Consolidated Valve Name Plate Data J

5) Drawings j ti-533 Sht 1 Rev. 15 i M-533 Sht 2 Rev. 12 l M-533 Sht 4 Rev. 11 M-533 Sht 5 Rev. 13 1

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REQUEST FOR INFORMATION (RI)

RI NO: 112 SYSTEM CODE: MFW ISSUE DATE: 8-6-87 i

SUBJECT:

BASES FOR THE MAIN FEEDWATER PUMP-TRIP AND ALARM SETPOINTS DEPARTMENT: NUCLEAR ENGINEERING COORDINATOR / EXT: TOM TELFORD/3849 TEAM LEADER / EXT: F. STOCK /3929 j CONCERN The bases for the main feedwater pump high discharge pressure trip, time delay trip and alarm setpoints are not defined. Lack of bases for setpoints may lead to equipment operation not in conformance with the l design limits of components in the MFW system.

REVIEW /RESULTS A review of the documents referenced does not provide adequate and consistent information to serve as a bases for the main feedwater pump high discharge pressure trip, time delay trip and alarm setpoints. The main feedwater flow control valves design conditions are listed in the original Bechtel design document as 1650 psig. The Bechtel design document and the Station Manual list the main feed pump shutoff head at 1650 psig. The SMUD Design Bases Manual, NEPH 5427, lists the pump shutoff head at 1450 psig. The Byron Jackson pump curve and vendor manual (M5.02-12) do not list either of these values.

The 1650 psig values, if used as the trip setpoint bases, are higher than the limiting design pressure of the tube side of the first and second j point heaters which is 1500 psig. (RI No. 108 was initiated to address I the problem of overpressurizing the first and second point heater tube j sides.) l REFERENCES

1) Process Standards A.P. 152, Rev. 20

2) Bechtel Design Bases Document

3) SMUD System Design Bases Manual NEPH 5427

4) SHUD Station Manual

5) H5.02-12, Byron Jackson Pump Vendor Manual

6) M5.03-57, Westinghouse Instruction Book for Nuclear Feed Pump Drive Turbines

7) M6.01-7, Westinghou:e Instruction Book for Feedwater HeatGrs L_____-_-___-_____-___-_-__

REQUEST FOR INFORMATION (RI)

RI NO: 127 SYSTEH CODE: MFW ISSUE DATE: 8-13-87

SUBJECT:

TUBE PLUGGING IN HLGH PRESSURE FEEDWATER HEATERS 18 AND 2A DEPARTHENT: SYSTEM ENGINEERING COORDINATOR / EXT: J. ITTNER/4701 TEAM LEADER / EXT: F. STOCK /3929 POTENTIAL CONCERN /0UESTION High pressure feedwater heaters 18 and 2A (E-3218 and E-322A) appear to have excessive tubes plugged in the Drains Cooler Area of the heaters.

With these tubes plugged, the amount of cooling for the condensate is reduced, the temperature of the drain water to the suction of the Heater Drains Pumps increases, and the NPSH to the Drains Pumps decreases. This may result in excessive tripping of these pumps.

REVIEW /RESULTS A review of completed Work Requests shows that 1st point feedwater heater IB has an estimated 397 tubes plugged. Also, 2nd point feedwater heater 2A has an estimated 559 tubes plugged. This represents an estimated 13.2% of the total tubes in the IB Heater and 23% of the total tubes in the 2A heater. A review of various tube plugging maps shows that, in both affected heaters, the predominant number of plugged tubes appears to be in the drains cooler area of the heater.

An interview with Operations Personnel has noted that since the 1985 refueling outage there has been an increasing problem with the Heater Drains pumps tripping on low suction.

At the time of the December 1985 unit shutdown, two separate but related '

actions were in effect:

1 Operations, in order to counter the low suction trips being 1) experienced with the Heater Drains Pumps, had reduced the low q suctioh trip point from 7 psi to 4 psi and had raised the heater '

levels up to one (1) inch below the high level dump.

l 2) A substantial amount of instrumentation had been placed on the Heater Drains Pumps trying to determine the causes of the trips ,

experienced by these pumps.

A review of the effects to the Main Feedwater System, and to the plant has found the following:

1) When a Heater Drains Pump trips, it initiates a start to the stand-by condensate pump. j i

RI No: 122 (Continued)

2) This causes a shock to the MFH system and to the condensate pump.

3) If more than one or two trips of Heater Drains Pumps occurs per day, problems with packing of the resin beds will be noted.

4) .With the unit at less than 75% load, the start-up of the stand-by condensate pump could adversely affect flowrates.

5) Excessive tuce plugging causes an increase in flow through existing tubes, a reduction of heat transfer to feedwater, and a reduction in feedwater heater efficiency.

Referencing RI 085. Lack of Long Term Lay-Up, the potential exists that corrosion has attacked the unplugged tubes and additional tubes could fail, therefore compounding the problem.

REFERENCES

1) Hork Requests 93379, 93388, 93387, 93390, 93353, 93352, 98462

2) Westinghouse Feedwater Heater Instruction Hanual, M6.01-7.

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