ML062650095

LTR-06-0470 - Robert Leyse E-Mail Re Tube Replacement for Main Condenser at Columbia Generating Station

ML062650095
Person / Time
Site:	Columbia
Issue date:	09/19/2006
From:	Leyse R - No Known Affiliation
To:	Trever K Office of Nuclear Reactor Regulation, State of ID, Dept of Environmental Quality
References
LTR-06-0470
Download: ML062650095 (29)

Text

OFFICE OF THE SECRETARY CORRESPONDENCE CONTROL TICKET Date Printed: Sep 21, 2006 09:53 PAPER NUMBER: LTR-06-0470 LOGGING DATE: 09/20/2006 EDO ACTION OFFICE:

-7o .- A EDO AUTHOR: Mr. Robert Leyse DEDURS DEDR AFFILIATION: ID DEDIA AO ADDRESSEE: Mrs. Kathleen Trever, ID Dept of Environ. Quality

SUBJECT:

Tub replacement for main condenser at Columbia Generating Station ACTION: Appropriate DISTRIBUTION: RF LETTER DATE: 09/19/2006 ACKNOWLEDGED No SPECIAL HANDLING: Immediate release to the public via SECY/EDO/DPC NOTES:

FILE LOCATION: ADAMS DATE DUE: DATE SIGNED:

7eVý;

Page 1 I CHAIRMAN - Tube replacement CHAIRMAN - main condenser for main replacement for at Columbia condenser at Columbia Page 11I From: <Bobleyse @aol.com>

To: <kathleen.trever@deq.idaho.gov>

Date: Tue, Sep 19, 2006 8:17 PM

Subject:

Tube replacement for main condenser at Columbia Kathleen:

Five years ago we had e-mail exchanges regarding the Columbia Generating Station. You contacted the NRC and they correctly responded that Columbia was well aware of the situation at the River Bend BWR in Louisiana (fouling of fuel elements). Of course, as usual, the NRC (and Columbia) did not elaborate.

The other day I was crawling around GOOGLE and I stumbled across the following:

www.energy-northwest.com/downloads/Main%20Condenser.pdf and www.energy-northwest.com/downloads/Main%20Condenser%2OAddendum%201 .pdf I do not believe that Columbia intended for these to hit the fan, but they are out there.

So, to finalize. INL is the center for Nuclear Power Technology in the USA.

The INL experts, independent of EPRI, should look into the situations that are outlined in these two documents. My belief is that Columbia has postponed tube replacement in the main condenser for too long.

In the hands of experts the two documents will speak for themselves. So, please let me know what INL thinks about all this.

The Chairman, NRC should insure that NRC is aware of the two referenced documents and that they are placed into the PDR.

Bob Robert H. Leyse bobleyse@aol.com P. O. Box 2850 Sun Valley, ID 83353 (208) 622-7740 CC: <Chairman @ NRC.gov>

c:ktemp\GW}O0001 .TMP Page 1 I Mail Envelope Properties (45108885.F5A : 21: 3930)

Subject:

Tube replacement for main condenser at Columbia Creation Date Tue, Sep 19, 2006 8:16 PM From: <Bobleyse @aol .com>

Created By: Bobleyse@aol.com Recipients nrc.gov OWGWPO02.HQGWDO01 CHAIRMAN CC deq.idaho.gov kathleen.trever Post Office Route OWGWPOO2.HQGWDOO1 nrc.gov deq.idaho.gov Files Size Date & Time MESSAGE 1285 Tuesday, September 19, 2006 8:16 PM TEXT.htm 2727 Mime.822 5465 Options Expiration Date: None Priority: Standard ReplyRequested: No Return Notification: None Concealed

Subject:

No Security: Standard Junk Mail Handling Evaluation Results Message is eligible for Junk Mail handling This message was not classified as Junk Mail Junk Mail settings when this message was delivered Junk Mail handling disabled by User Junk Mail handling disabled by Administrator Junk List is not enabled Junk Mail using personal address books is not enabled Block List is not enabled

I-Columbia Generating Station Main Condenser By W. Scott Oxenford, VP Technical Services This document summarizes longstanding performance issues related to the design and operation of the Main Condenser at Columbia Generating Station and solutions to those challenges.

The following categories summarize the issues in introductory level detail:

1. System Components Overview

2. Condenser Leakage

3. Columbia's Condenser

4. Columbia Historical Actions

5. Can Columbia Eliminate Condenser Leakage by Eliminating Debris?

6. Industry Data and Experience

7. Solutions Addendum 1 has been included to highlight costs associated with condenser leakage.

Section 1: System Components Overview The Purpose of the Main Condenser The main condenser is a key component in the closed-loop system that transfers energy from the reactor to the turbine, in support of creating electricity. The condenser's primary function is to take steam exhaust from the main turbine and return it to a liquid form. The liquid, called condensate, is highly purified water. The condensate is preheated and pumped back to the reactor pressure vessel where energy in the form of heat is added to convert the condensate back into steam.

See Figure 1 for a simplified diagram (page 9)

Condenser Configuration The Columbia condenser has three main sections:

1) The steam space, into which the turbine exhaust and other steam sources discharge.

2) The cooling section, where steam passes over brass water pipes filled with cold circulating water, causing the steam to condense back into water (condensate).

3) The circulating water interface consisting of waterboxes, tubesheets, and thousands of tubes. Chemically treated Columbia River water is circulated through special brass tubes, removing heat and transferring it to the Cooling Towers.

CGS Main Condenser White Paper Revision 1, June 2006 Page 1 of 22

I-Cooling Towers The cooling towers provide a water source for the circulating water system and transfer heat to the environment. Evaporative losses are replaced with water from the Columbia River. By nature, the cooling towers act to concentrate debris and impurities. Acid and other chemicals are added to reduce secondary system fouling and corrosion.

It is paramount to prevent the chemical additives and raw water/organic materials from degrading reactor coolant quality.

Section 2: Condenser Leakage What Happens During a Small Condenser Tube Leak?

Due to pressure differences, small amounts of chemically treated raw cooling water (circulating water) are transferred to the pure reactor grade water in the condensate system. This water is then run through filters, removing some of the introduced impurities. Impurities that get through the filters then go to the reactor vessel, where they begin concentrating. The concentration takes place as the pure water boils into steam and the impurities are left behind.

As condenser leakage increases, the filters become less and less effective at removing the impurities.

Limitations to the Columbia Design Some Boiling Water Reactors (BWRs) were designed with, or subsequently added, additional filters in their condensate systems. Called deep bed demineralizers, they are located between the filters like those at Columbia and the reactor pressure vessel. The deep bed demineralizers enhance filtration and water quality prior to entering the reactor. They allow continued safe operation with much greater condenser leakage than is possible with Columbia's design. Additionally, the filters are effective at removing copper, which will be discussed later.

Results of a Small Condenser Leak Even a small condenser leak has negative consequences for Columbia, including:

o Filters must be changed more frequently to keep the water as pure as possible.

Changing filters twice as often (frequently required) increases the cost of the filter media (resin) and the associated disposal cost (radioactive waste that needs to be buried). Each of these operations and disposal maneuvers also impact labor costs and employee dose (radiation exposure).

o Once a leak is large enough to locate, the plant is reduced to approximately 60%

power to pinpoint and repair the leakage. Pinpointing and repairing leakage from multiple, small locations, is especially difficult. Each repair entails unplanned CGS Main Condenser White Paper Revision 1, June 2006 Page 2 of 22

5-_

generation losses, employee exposure, personnel safety hazards, and increased labor costs.

See Figures 2A-B (pages 10-11) o Water quality (chemistry) within the reactor degrades. This can:

1) Result in unplanned power reductions or mandatory shutdowns due to exceeding chemistry limits.

2) Increase activation of impurities, which increases radioactive contamination and exposure throughout the plant.

3) Increase the susceptibility of the reactor vessel and internals to cracking, increasing the likelihood for costly repairs.

4) Disturb the corrosion layer on the fuel and reactor internals. Impacting the fuel corrosion layer can lead to fuel damage. Fuel damage can result in plant de-rate, unplanned refueling outages, increased dose rates and employee exposure, and increased stack release rates to the environment.

Section 3: Columbia's Condenser Admiralty Brass Material Columbia's condenser tubes, like many original condensers, were fabricated from admiralty brass. Admiralty brass is made primarily of copper, with the second largest constituent being nickel. It was selected for its excellent heat transfer efficiency and inexpensive cost relative to other suitable materials.

Susceptibility to Mechanical Wear Admiralty brass is more susceptible to damage than the other contemporary condenser materials like stainless steel and titanium. For example, plastic tie wraps have caused leaks in our condenser when they became lodged at the inlet end of condenser tubes and, moved by water flow, wore holes in the soft metal tubes. Titanium is approximately 6.5 times harder and stainless steel is about 3 times harder, making them less susceptible to debris induced damage.

Likewise, steam leakage from exhaust lines into the condenser has been known to wear through tubes, leading to rapid increases in condenser leakage and prompt shutdown of the plant to protect primary system chemistry.

Copper and Fuel Even slow wear of the soft condenser tube material adds copper to the condensate.

Columbia demineralizers are not designed for mechanical filtration, the best method for removal of copper. Based on that and the lack of deep bed demineralizers, Columbia is classified as a 'high copper plant'.

Copper's substantial negative impacts on Reactor fuel integrity were identified in the early days of Boiling Water Reactors. A phenomena, known as Crud Induced Localized CGS Main Condenser White Paper Revision 1, June 2006 Page 3 of 22

J Corrosion (CILC), is caused by copper entering the reactor, attaching itself to the fuel corrosion layer, and causing localized corrosion and high temperature areas on the fuel cladding. The eventual outcome is often loss of clad integrity and long axial splits of the clad. That allows fission products to spread throughout the plant and ultimately cause increased release rates to the environment. CILC has rendered large quantities of fuel unusable, costing tens of millions of dollars and extended reduced power operation at some units.

See Figure 3 (page 12)

The industry has substantially lessened, but not eliminated, CILC failures by removing copper from their condenser materials or adding deep bed demineralizers. Columbia has done neither, leaving us susceptible to CILC fuel failures. Columbia has carefully selected fuel cladding to minimize the risk of CILC failure. However, the only real way to rule this failure mechanism out is to remove the source of copper completely.

In addition to fuel impacts, copper is also implicated in the trapping of cobalt in the corrosion layers on all reactor internals. This increases overall plant radiation levels and dose to our employees.

Early Condenser Damage Poor chemistry control in the early years of Columbia's operations caused corrosion of the condenser tubes. One result is a phenomena, called dezincification, which caused pits in the condenser tube metal. The pits remain and provide initiation sites for localized corrosion and subsequent tube leaks/failures. Based on this, Columbia cleans and "eddy current tests" one-third of our condenser system per outage. With our transition to two-year cycles, Columbia needs to start conducting eddy current tests of all the condenser tubes each outage, starting with R1 8 in 2007. The $700k per outage testing cost could be substantially reduced with improved condenser material condition.

Section 4: Columbia Historical Actions Columbia management conducted a condenser replacement study in 1996. No action was taken on the study results based on unfavorable payback expectations and extended outage time for condenser tube replacement. A key factor at the time was the uncertainty of plant license extension.

Our concerns resurfaced in 1999 following fuel failures at the River Bend plant (admiralty brass condenser with deep bed demineralizers). We closely tracked the River Bend cause analysis. River Bend fuel corrosion had high copper levels, but the failures were attributed to high iron levels in their corrosion layer. Based on Columbia being a low iron plant, no action was taken.

See Figure 4 (page 13)

CGS Main Condenser White Paper Revision 1, June 2006 Page 4 of 22

During 2001, Columbia found that some of its fuel had thicker than expected oxide layers. A root cause team, with industry expertise, studied the previous operating cycle and fuel scrapings. The fuel had higher than normal levels of copper and iron deposits.

Concerns over probable fuel damage were high. Spallation (similar to concrete spallation where material falls off) was identified on Columbia fuel.

See Figure 5A, B, C (pages 14-16)

The root cause was determined to be poor demineralizer performance, coinciding with a chemical intrusion due to condenser system leakage. Had the condenser not leaked this challenge to the fuel would not have occurred.

In 2003, another copper reduction study was initiated that included consideration for deep bed demineralizers or removal of the admiralty brass. The recommended solution was not completed due to external cost pressures.

Columbia's management has thoroughly reviewed options for managing ongoing condenser challenges. On each occasion, continued operating risks were accepted instead of taking action, primarily to avoid costs and extended outage length.

In addition to these studies:

" Columbia has increased the size of our demineralizers to improve filtering efficiency.

• Determined the suction screen on the circulating water system was not properly seated, allowing some debris to pass. Columbia has corrected this and implemented a long-term fix.

" Columbia rebuilt three cooling towers, upgrading the plastic fill and lattice, while removing all plastic tie wraps at $2M per tower. Three towers remain original.

• Columbia has improved our foreign material controls to reduce debris getting into circulating water and subsequently the main condenser.

" Columbia has improved waterbox drainage to allow faster and more complete draining for repairs.

" Columbia staff is looking at screen options in the upcoming outage to further reduce debris entry into the main condenser.

Section 5: Can Columbia Eliminate Condenser Leakaqe by Eliminatinq Debris?

In any raw water system, debris elimination is a challenge that plant designers are faced with. Columbia is blessed with a relatively clean water source in the Columbia River.

The Tower Make-up System takes water from the middle of the river through screens.

Columbia also has screens at the intake to the Circulating Water Pump Pits. These screens are designed to be small enough to prevent plastic tie wraps and larger debris from passing. Despite this, items pass through the screens or are in the system from CGS Main Condenser White Paper Revision 1, June 2006 Page 5 of 22

historical operation. Additionally, the screens must be manually raised for cleaning with the plant in operation which allows debris entry.

Cooling towers, due to their design purpose of transferring heat to the environment, are open and susceptible to items being blown in, dropped in from animals, and dropped in during work under adverse conditions. Additionally, the extreme weather variations, water flows, chemical additives, and ice build-up cause corrosion and damage that create debris. Any raw water screen system can reduce debris intrusion, but none appear to be 100% effective.

See Figures 6A-D (pages 17-20)

Finally, in 2003, INPO shared a Significant Experience Report on debris intrusion. The document shares operating experience with screens becoming plugged and causing loss of pump suction. This is an issue Columbia has experienced from algae build-up on plant restarts. Reduction in screen opening size increases the likelihood of plugging.

In May of 2004, a root cause analysis was performed to prevent debris related condenser leaks. Remaining actions from that study are planned for implementation in the upcoming outage. Columbia's actions to date have reduced the quantity of debris in the condenser, and should improve more with an improved screen system. However, debris intrusion will always be an issue to some extent.

It should be noted that the root cause 'does not address tube leaks caused by steam impincqement or long term flow induced erosion or other service related tube damage such as dezincification and stress corrosion cracking'. These failure modes were specifically excluded for the purpose of focusing on debris-related leaks, which caused the condenser leak triggering the root cause analysis.

Section 6: Relevant Industry Data Current Main Condenser Material Of the 34 US BWRs:

16 have stainless steel condensers.

10 have titanium condensers.

4 have a combination of admiralty brass with stainless steel or titanium. These sites use the less damage-susceptible materials in the highest risk areas.

Only 4 have admiralty brass condensers, including Columbia.

Our data shows at least 13 of the BWRs have re-tubed their condensers. Nearly all had admiralty brass and went to a different material. Most occurred in the 1980's and 1990's.

See Figure 7 (pages 21-22)

CGS Main Condenser White Paper Revision 1, June 2006 Page 6 of 22

Current Plants with Deep Bed Demineralizers Of the 34 US BWRs, 20 utilize deep bed demineralizers.

Of the 8 US BWRs containing some admiralty brass in their condenser, only two operate without deep bed demineralizers to address copper. They are Columbia and Vermont Yankee. Vermont Yankee went commercial in 1972. It is a small 593 MWe BWR recently bought by Entergy. Vermont Yankee is planning condenser tube replacement as part of license renewal.

Two of the US BWRs with a combination of admiralty brass condensers and deep bed demineralizers are Limerick Units 1 and 2. Following major CILC related fuel damage on Unit 1, Limerick added deep bed demineralizers. This option was selected over re tube because it was factored into the original design, with available space in their Turbine Building.

From this section, the case for change, based on copper alone, is strong. We are one of only two operating BWRs that have admiralty brass condensers without deep bed demineralizers. The other BWR, Vermont Yankee, contains 8%

stainless steel tubes.

Utilities invested in their facilities to reduce risk. At this point we do not know if their investments passed a business case payback analysis or if action was taken to eliminate the large downside risk, regardless of payback.

Political Landscape Over the past several years, top focus areas of Chief Nuclear Officers have been Security, Fuel Reliability, and Materials Degradation. In the area of materials degradation, the industry established a program called BWR Vessel Internals Protection (BWRVIP) in 1994 so we could self-regulate, rather than cause the NRC to regulate us.

The program provides research, inspection requirements, program requirements and independent audits to ensure the industry is protecting reactor pressure vessels and internals. Failure to protect these important components can have downside risks not only to individual stations, but the nuclear industry as a whole. We are currently failing to meet the BWRVIP guidance on copper in the reactor coolant, which provides a spotlight on Columbia due to having one of the more significant program deviations.

Peer pressure to eliminate long-term deviations is growing.

Section 7: Solutions:

Deep bed demineralizers alone are not a preferred solution. They will reduce copper and impurities in the reactor coolant, but condenser leakage will continue to be a chronic problem and copper impurities will remain at a lesser amount. Unplanned downpowers and radiation exposure for condenser repairs will continue, but less frequently. Resin usage and radioactive waste will increase due to the large size of the CGS Main Condenser White Paper Revision 1, June 2006 Page 7 of 22

z deep bed demineralizers. We also anticipate increased Security staffing due to an additional building to house the deep bed system.

On April 21, 2006 we entered into an agreement with Sargent & Lundy to perform a Feasibility Study on the main condenser. They recently did similar work for four Exelon BWRs and the Fort Calhoun Station. This will entail a comprehensive analysis of Columbia's history and that of the industry, resulting in recommendations to ensure long-term reliability of the main condenser. The study will be complete prior to the FY08 budgeting cycle. Engineering, design, and procurement are expected to start in FY08, with installation of some or all of the modification in R19 (FY09).

Condenser material replacement is clearly the preferred solution to eliminate leaks and copper sources, ensuring long-term reliability of Columbia's fuel, reactor vessel and internals.

For maximum protection and defensive strategy, installation of deep bed demineralizers in conjunction with condenser tube replacement is another solution. This is not currently under consideration. However, as the industry gains operating experience in fuels and materials degradation, the Columbia staff will stay abreast and take action as appropriate.

CGS Main Condenser White Paper Revision 1, June 2006 Page 8 of 22

ZCooling Tow ers] FIGURE 1 -3 Circulating Water System

- T /11- airflow Wind 44.

[

I I CW Basi L~.

---

CW S re n

-J V

Tubes SiCondensr Tubes Tube D Sheet #2 E

B I

IR Tube S Sheet #3 - Tube Tube Sheet #4 Sheet #1 Outlet Intermediate Inlet CGS Main Condenser White Paper Revision 1, June 2006 Page 9 of 22

FIGURE 2A, Main Condenser Waterbox Entry into the condenser waterboxes at power is a challenge to personnel safety. Single isolation valves (some eight feet in diameter) provide worker protection from system pressure. Entry is through small manways as shown in the picture.

CGS Main Condenser White Paper Revision 1, June 2006 Page 10 of 22

FIGURE 2B, Main Condenser Waterbox This shows a worker inside the condenser waterbox.

CGS Main Condenser White Paper Revision 1, June 2006 Page 11 of 22

FIGURE 3, Fuel that has undergone CILC related failures.

NOON=-=& ,L-CGS Main Condenser White Paper Revision 1, June 2006 Page 12 of 22

i FIGURE 4, Failed fuel due to crud and accelerated corrosion.

This fuel was exposed to anomalous primary coolant chemistry, resulting in a heavy oxide layer and accelerated corrosion in 1999. It was fresh fuel.

-~

IJ~ 4

( dl 7

V

'ci I

CGS Main Condenser White Paper Revision 1, June 2006 Page 13 of 22

FIGURE 5A, One Cycle Fuel in expected condition.

The middle fuel rod has been brushed to remove the oxide layer.

CGS 1-Cycle Bundle (Before Chronic Condenser Leak) 1: A2 CGS Main Condenser White Paper Revision 1, June 2006 Page 14 of 22

FIGURE 5B, One cycle fuel with it's oxide layer impacted by chemical contamination.

Nodule formation has begun.

CGS 1-Cycle Bundle (After Chronic Condenser Leak)

-. ~,

- '"~1 CGS Main Condenser White Paper Revision 1, June 2006 Page 15 of 22

FIGURE 5C, Fuel that has been in the reactor for four cycles, following chemical contamination in the last cycle. Nodule formation and spallation is evident.

CGS 4-Cycle Bundle (After Chronic Condenser Leak)

CGS Main Condenser White Paper Revision 1, June 2006 Page 16 of 22

FIGURE 6A, Cooling Tower As illustrated, the cooling towers have many openings to the environment that allow debris entry.

NORMAL. MULTIBLATZ PAN OPERAThrG WATER LEVIL DIEIRIUTI.ON FLUME OISTRISBIXIM BASIN PERIMETER WINO ICREEN .-.

I*- c..w INLET

- - R PRECArT LOUVERS TO'C.W. SY1MMETRICAL ABOUT C TOWYER PUMV INLET FLUME 6-90931.4 LT JAN 19N.II CWITPMIJ FIGURE 4. COOLING TOWER CROSS SECTION CGS Main Condenser White Paper Revision 1, June 2006 Page 17 of 22

FIGURE 6B, Cooling Tower.

Large fans and vertical louvers allow debris entry pathways.

CGS Main Condenser White Paper Revision 1, June 2006 Page 18 of 22

FIGURE 6C, Cooling Tower Inside a drained Cooling Tower. Workers are careful to remove debris prior to returning it to service.

ii CGS Main Condenser White Paper Revision 1, June 2006 Page 19 of 22

FIGURE 6D, Cooling Tower.

This drained Cooling Tower demonstrates how open to the environment they are. When in service, water fills these passages and falls to the basin below.

I II

'4I I

41.

CGS Main Condenser White Paper Revision 1, June 2006 Page 20 of 22

FIGURE 7, FERMI Condenser Replacement Article INDUSTRY NOTES PROCESS/MANUFACTURING ILIIES Sleam gra na-n Preplanning, analysis key to condenser retubing Desabdon of condensers and the poota Ws! for 5hed ouases or plant od sWrce onsntd dhat ulte continualy ovrl.

'tzs mate the possible need for condenser powerlats has been pz Jv~si

d. bedtwettr 2n5%;5=u* ie lb-seamm-generoar corrosion tn pressut imd-w w (PWlR ) plants and foa meembi corrosion In bolllg-wa r-li (s*Jpta . 51c***s~s*

1-0=1 Ust A, a taWK pln or Loemt Edison Co. is located on Lake Erie. a freivah- body of velatively good quality The pbsthas a closed circulating-w ypm *CMWS) that tedes on be Itk rhr r akeup. TIM CCWS comprises a pond.

Aive &aczhing-water pumps. an Admia.

tqyonw d, siogte s condlenser and o t~e mfac an hionnuurmaresdamnanded qiedal Radoaclw ontmbtllo two nama-daft colioe lower~ General precauftris hper-iA o polecton key concern, the Can order of business margnal experience focused on the lenth of tde oun*&, t die This mraegy rusulted in two very good past trumbig of BWR pants of similar proposals, and the award decision was size and condenser-tube sumber has bated primarily on the cotractorz man required from 7S to 110 days-liss for agemen -m and its experience In work.

condensers with significansly fewer tubes leg together on similar pjects. Stccs of or R*prial- condenser-eshe replacements. the approach is measmued by the fct that 1uaseleged ;u e ovlde. a 65-day die project was completed aed of sched ule with a quality product and only 3% in aggressiveeoaslriic-ion schedule and additons tom d origind contract plice.

incentive. detailed prepla*ning such an achlevemeom clearly, could Using previous historical data. end Input not have been accomplished without a from Fermi 2. a utility consultant deel thorough analysis of the problems aped a construction schedule allowing 75 Involved, evaluation of the available W.IJ " t ot O rtd m i"trie*t- to days fom entry int waxerbo.= to com options and associated limitations, a conntl katdwter.-copper buildup Is one pletion ofthe Concluding clzsalating-water deaed and tcallstic project schedule and prevuen qiaproach I-rd C Pron. the Wit Allowing Sr pve-o*-age w*erk we of complete agreement on job-specific activi WtIlts condenser proec MAnAgC4 sates sparat stand-alone fcilities. and sharp des-eli1 predicated an creation of a dose dug i opper to levels down ft0.2 focusing of the job to minimize h&rerer knit eram with a inilled qppmnach.

ppb adverly affects demlnerllzert na CD0cs ftm Other outage activitii". the pro Iis was accomplished over a period of times -an Increases mequuments for red joct team shortened the schedule to 6S nine months starting InJul 199D. when waste pm essing and waste d<posallsor day Ambitious as it may have seemed. the contract was awarded to United Meg ag. Rmova-l of die mof o,=eo fthrequiremetnt was incorporated into the sees & Conmtcorsamlyt*l, Philadel project specification. so bWdd .wer pte phia. Pa. and astmzatioana Interfacing pae to prescu detailed 65-ay acheftiles commenced. Neoulning in September. the denser IsDectsuber I8. and the modill at the prebi meeting. general eotra:tor and Its aubcontrac cation was aeted for die saflocg oulag In accordance with utility policy for tots-Heat Eb.chager Systems Inc.

RRM schedul ftr Much 1991. A ftr major contrats, the team established a Boton. Mass, &AiCsanoo-Slir. P -ilade Mal prj=e aralatio was art up InJm flixed-price nontract for ratubing the am phis, Pa-woesk closely with the project awy 1990 is stuy, dy etal and implement deser and developed a detailed specifica tam to ptI; a detaled schedule, locate fte mogjlcgku the staff lmetioulg assa tiou, the heatt of the contract. 7his didnd providers of goods and servles and con complcety self-reliant nti both before Preclud the reqirernent of prices hor spe duct the accessery analyses related to and during the outage. In a to Proc.

ndion ific ac'vities.manpower Woading a m[ie tobetbeet stability. sube,'besheet-joint.

key staff m*mbers were John HonkAa, stone schedule, and a detailed activity strength, and prot:ective-coting evalua condenser project engineer, and John schedule. A detailed reference bid. mwas fions. So dose an smooth were thelIter O'Dou*a W.enser fe Oiee over. was prepared to provide a hbais hr actions smoog involved personnel during With at kiss of gneating capacity a exehiding low bids horn contractors with this WeWothat, by December 1990. ftey CGS Main Condenser White Paper Revision 1, June 2006 Page 21 of 22

• wee no longer idemti6ed by their individu asafety factor of two. outages. Tubesheets were also inspected

.a organizations but a the Condenser Pro AddItlonI atnalyses were related to and special tube-worktooling determined.

ject Team. condenser uplift. cathodic protectiONi tube Stearn-side condition was established and Prelect e0lments. The primary -old vibration. ad effects on circulating-water damaged components were fabricated erazions of the project were selection Oflde flow. Stuctural stability was a factor before the start of RF07- The presence of tube material and the replacement method. because the full complement of 22-BWG ust nodules indicated areas of MWC.

The ieplacement material would have to titanium robes would be over one-million Selection of the tubesbeet coating equal the ptnt's performance experience pounds lighter than their predecessors. required extensive research into the need with Admiralty brass: operin Close to Analysis showed that resulting uplift loads for surface preparation before application design rating with fewer than 1% of the could be accommodated by the existing of the coaing. This was dictated by reports tubes plugged and fewer than 1% with foundaitons: anchorage. and structure. indicating premature coating failures were 50% wan thinning. Othe ntalteish-leted Tests to deemine the'need for cathodic likely In MIC-affected are if corrosion cancern were suscepuMilly to corrosion. protection because of metal dissimilarities and bacterial colonies were aot removed erosion. and fouling at the imal surface. cocluded that the subesheet could be pro before the coating was applied. Possible

-- materials evauated" cted from galvanic corrosion by costing solutions, ranging from ozonation to Included 1ypcs 304 and 316 (austenitic). aone, without use of a sacsicial anode or mangement of steam chambers and flush Type ALAC (-super'ausienitic), TYPe levessd-Iretmu cathedic proceed ing of tubeshect surfaces with potable 439 crfrxic) and Sea-Qe (euper" frth Corosion Calculations based on inea wa*r, appeared cost- and labor-intensive; 1c) stanless steel$, and titanium. Tbe smeesentt made on ftst assemblies placed limited documentation was available to mssgnit sees were ao considered suit in the circuleting-wate pump house Mfu provide bacteria counts before and after able because of the aced for water-a1de mind expected corrosion rates below 10 treatment to verify the effectiveness of hyup procedogs Type 439 was eimne mUflz4 Because other approaches wee efforts at eradication.

because of susceptibilit to pitting and ats-proahbitive, and assuming no coating Accordingly. a treaument process was tervice corrosion. Although the costs of Imperections or failures, it was decided developed that would not impact the the snPer" stainless seels and titanium that a thick Ailm coating with high impact schedule nor be toxic to personnel or the were comparable tianium was; selected rsistc and excellen flexure. cathodic environment- It Involved hydroblastinSg.

di~shoodmet= and dileltc-acuimnth peep spraying with hydrogen peroide, sad hpowerpta m OR Snwservice. In attics would provide adequate tubesheet blasting, end washing with methylethyl ketoxime (MEK). A mockup tubeshe was mcreover, has beeosccessful Tube-vbIrUon analysis indicated that prepared, Admiralty brass tubes were Replacement althuatives were the ansupported span length oftUhnnei' rolled In. and the assembly was hamsed jebundling. retubing only, and rebing wailed titanium tubes would have to be in circulating water on the pump scuod with new nihesbaets. Replacemenzof tubes reued o prevent virAtion-Induced fall aide for six weeks, allowing buildup of a s grups (bondles)--loue with gr-ea suc uses This dictastd the need for staking the slime and corrosion layer imila to that cess at several Scandinavian unclear tubes. counfiming the eperlence at other developed on the condenser tobesheets.

plnatts-was not possible at Fermi 2 plants. Thbes in the air-cooler sections Examination of dre assembly before stat because of the plato layout and interfer were not included because of tbe far Iowea meat tvealed the presecaf of torrosive ence. This required hand removal of velocities.that they would be subjected to d-producing bacteria tubes, negating schedule advantages and the amovat of work involved In The examInaston was repeated after offered by modula repla-cL installing sakes In these shrouded sections. each step of the eradication procedure. The Despi*e galvnic lnCoUmPaslfiY, I* wa Type 304 stainless was chosen over end result was that 94% to 99%af the bac decided so tain at existing carbon steel other possible"staking materials for its teds populato was IlMed by kydroblast tubecheets, primarily because the cou smooth sudace finish, car*son resistance. ing, and another 2% by the pride wash.

denser h enteoutlet waterboxes, which and ea of installation. A dimpled stake Following the M.EK wash, total kill was would have bad to be dismantled to install design was selected because it offered a 97% to 99%. This analysis enabled the titanium outlet tobesheets. The inlet locking cpabfi. The Upartt developed elimintoa of MM from the procedure.

tubesheets could have been replaced by for full bundle staking required about Edamt Implemnsting the procedure during removing the inlet wetbome and uting 36.0stakes ofvaying length. the outage. water samples wer tak from the tubesheet-to-em a-df weld. But Anbass of crcula*ti-water low id MIC-affected areas for batel dats. Com this would have had to be replaced by a ca*d linle inpact on tube cleanliness, con parionto samples taken after hydtnbas mechanica joint. introducing a potential denser pressure. or net generation would ing-allowiag time for bacterial foreskage result firm the reduced tube velocities ina growvth-shwe a 75.2% reduction in the Analysis of tubesheet and tube-joint titanium-tube coudenter-from 7M ftse bacterial colony count the reduction loads indicated no significant change to 6.53 ft/sec with five pumps operating. achieved by hydroblasting followed by would resul frAmrembibg with tian*um* firm 6.8 o 5,80 ft/sec with four pumps. peroxide apraying was 97.i%.

$oint-streogth tests were conducted to Velocities were judged adequate to main The balance of the detail pe-otiutge determine the acceptable tube-rolling min tube cleaniess factor at an estimated planning and activities called for by the torque muder the allowable 1340-5I90-lb 90%. No appreciable Increase Innat gen retubing specification proceded on or foces expected at 55 sig. the design pres stion would eccur with five pumps until ahead of schedule. As a result, the 6,000, tare of the citrc-wat" syssm Five 38-hole the circuladntg-wavter inlet temperature tube condenser was retubed, coated. and mockup tubeseets wee made for pullout reaches 7*or hWghem tested In a period of 62.5 days with scar tests, two of hem poxy-coated to rel Remaining uneeflalntlaa bad to do lawles woaganshup. The wock was com cate the Intended resnbed-condenser with the condition of circulating-water pleted 25 days ahead of chedule and 20D%

mbesheer end-product. About 10% of the valves, Inlet and cutlet tubesheet. con under the budgeted cost-all the more titanium tubes tested wer coated with denser staun side. and suppon plates. PFo notable for rviAng been achieved despite LTocne prior o wlin. Tt results dictated aible concerns lnclded valve leakag,. sup complicating conditions: contamnated rolong to, ques of 10.5 and II ft-lb at the port-plate bowing, and microbiologically tbesheems radloactive tubing, and the use Inulet and oudetrespectively. DBaed on the Influenced corrosion (MIC) of tubeshects. of special clothing to protect penonnel wat-caws pullout forcls. dese torque val The valves were clend. inspected, and fm contamination at the watesbox fves lanproduced a nibe-so-ndesliertjoint with adjusted for seating during svead krced (see photo). IBel Strauss to~ru U .A#, Ista CGS Main Condenser White Paper Revision 1, June 2006 Page 22 of 22

Columbia Generating Station Main Condenser, Addendum 1 W. Scott Oxenford, VP Technical Services This addendum augments the Columbia Generating Station Main Condenser white paper, providing a summary of economic impacts of condenser leakage.

The analysis is organized in two parts for clarity. The first provides an average cost per event or month. The second provides a cost breakdown over the current operating cycle, from June 2005 through May 2006.

Historical Perspective Columbia has suffered eleven shutdowns and nine reduced power evolutions to address main condenser leakage since it began operation in 1984. The number of events speaks to the chronic nature of this costly operational challenge.

Condenser related shutdowns and down-powers would have been even more frequent if it were not for repeated plant shutdowns, extended economic dispatch periods due to river flows, and annual operating cycles. Each of those operational attributes provided opportunities to perform condenser repairs reducing the potential for even more condenser related shutdowns.

Direct Cost Impact Chemistry Control Columbia's condensate filter demineralizers are changed more frequently to minimize impurities reaching the reactor pressure vessel. The demineralizers are coated with a powdered resin. The costs of increased resin use, shipment, and disposal of the associated radioactive waste is included. Additionally, the circulating water system is operated to reduce the level of impurity concentration, requiring increased chemical treatment.

$124,000/month Average chemistry-related cost for each month Columbia operates with a condenser leak.

$1,030,000 Aggregate chemistry-related cost for this operating cycle (June 05 to May 06).

Tube Plugging Evolution A tube plugging evolution is performed at reduced power and takes about three days. Detailed planning, oversight, and around the clock coverage limit lost generation. The actual tube plugging activity involves isolating a section of the CGS Main Condenser White Paper Addendum 1 Revision 1, June 2006 Page 1 of 4

condenser, draining it with multiple pumps, cleaning the tubes, identifying the leak(s) and inserting plugs. The evolution involves Columbia staff level of effort, overtime, and the use of contractors.

$350,000/evolution Average incremental direct costs associated with one tube plugging evolution.

$1,400,000 Aggregate cost of the four tube-plugging evolutions this operating cycle (June 05 to May 06).

Indirect Cost Impact Radiation Exposure Columbia's main condenser location exposes personnel to radiation during repairs. Keeping radiation exposure 'as low as reasonably achievable' is everyone's responsibility.

Radiation exposure is closely monitored by Energy Northwest, the Nuclear Regulatory Commission, and the Institute of Nuclear Power Operations. A non outage month at a top performing boiling water reactor is less than 2 Rem collective radiation exposure, with a total for the year of around 30 Rem. Adding one condenser repair evolution jeopardizes the annual goal of 30 Rem or less.

2.262 Rem/evolution Collective radiation exposure to Columbia staff and contractors, per tube plugging evolution this operating cycle (June 05 to May 06).

9.048 Rem Collective radiation exposure to Columbia staff and contractors this operating cycle (June 05 to May 06).

Replacement Power Columbia conducts tube plugging evolutions at 65% power. Based on typical duration, a tube plugging evolution costs us the equivalent of one day of full power operation. Estimating the value of power of $32.45/megawatt hour produces the following indirect costs.

$1,000,000/evolution Estimated cost of replacement power per tube plugging evolution.

$4,000,000 Estimated cost of replacement power for tube plugging evolutions this fiscal year (July 05 to June 06)

CGS Main Condenser White Paper Addendum 1 Revision 1, June 2006 Page 2 of 4

Costs for 2001 Heavy Oxide Layer Analysis Columbia's staff had extensive fuel rod corrosion related concerns in the 2001 timeframe. A highly experienced industry team was formed to determine the root cause and initiate corrective actions. Condenser leakage was identified as the root cause.

$1,750,000 Cost associated with fuel scrapings, investigation, and research into heavier than expected fuel oxide layer.

One corrective action from the above investigation was to alter Columbia's chemistry controls to favor fuel protection over radiation source term mitigation.

The strategy was followed until the current operating cycle. Oxide formation on the fuel during this test period was normal, thereby validating the root cause determination. Favoring fuel protection created very high radiation source term at Columbia, resulting in increased staff radiation exposure. The impact is difficult to quantify, but very real. Columbia's radiation exposure performance is in the worst quartile in the industry. Columbia is currently the worst plant based on source term measurements. To counteract this, a chemical decontamination of key piping is scheduled for our upcoming outage.

$1,700,000 Approximate cost of chemical decontamination in the upcoming outage to improve radiation source term.

Replacement Power Estimates Since 2000 Lost power generation (associated with main condenser leakage) since January 1, 2001 is equivalent to more than 12.5 days of full power operation. With an estimated value of power of $32.45/megawatt hours, the total cost is substantial.

$12,500,000 Estimated value of replacement power associated with Columbia main condenser leakage events since January 1, 2001.

Conclusion Various conclusions can be drawn from the above data. In simple terms, the author draws the following underlying conclusion, upon which others can build.

'The design and resulting poor performance of Columbia's main condenser has produced many direct and indirect costs and continuously challenged our ability to achieve operational performance levels expected of U.S.

nuclear power plant operators.

CGS Main Condenser White Paper Addendum 1 Revision 1, June 2006 Page 3 of 4

The chronic nature of Columbia's main condenser problem is unlikely to change substantially without addressing the condenser tube material.

Failure to address this issue will increase the risk of fuel damage. That fact alone is ample reason to replace the main condenser tubes. Replacement is also in the best interest of efficient financial operation of the plant as evidenced by the costly history of our present condenser equipment."

CGS Main Condenser White Paper Addendum 1 Revision 1, June 2006 Page 4 of 4