ML20042H025
| ML20042H025 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/10/1990 |
| From: | Hernan R Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9005170078 | |
| Download: ML20042H025 (41) | |
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Docket No. 50-289 LICENSEE: GPU Nuclear Corporation FACILITY: ThreeMileIslandUnit1(TMI-1).
SUBJECT:
SUtNARY OF APRIL 20, 1990 MEETING WITH GPU NUCLEAR ON STEAM GENERATOR FOULING INTRODUCTION The NRC staff met with representatives of GPU Nuclear Corporation (GPUN) and-theB&WOwnersGroup(BWOG)onApril 20,-1990 at the-NRC headquarters 1
building in Rockville, Maryland.. The subject of the meeting was fouling of the TMI-1 once-through steam generators (OTSGs) by corrosion products 1
introduced by the secondary coolant system. is a list of the attendees at the meeting. Enclosure 2 is the handout summarizing the GPUN
. presentation.
BACKGROUND In late 1985, during restart from an extended shutdown period following the THI-2 accident, plant power level at TMI-1 was found to be limited to about.87% due to high OTSG (downcomer) level. The-cause of the high level was flow restrictions in the tube support plate broached openings caused by deposits of.
corrosion products introduced into-the OTSGs by the secondary. system. This phenomenon had previously occurred and has since occurred at other B&W plants as well.
In January 1986, the TMI-1 main turbine and reactor were manually.
1 tripped as part of restart test program mandated by the-NRC. Following return to power operations it was discovered that plant. power level was no: longer limited by OTSG level; in fact OTSG 1evel corresponding to 100% power was about 12%
lower than previous OTSG 1evel corresponding to 87% power level (70% versus 82%OTSG1evels,respectively). The plant was able to be operated at 100%
power for the remainder of that fuel cycle without OTSG 1evels-nearing their limit. However following return to power after the 6R refueling outage (11/86 to 4/87), reactor power was again limited to about 83% by high OTSG j
levels.. After evaluating the options to remove this-limitation, GPUN opted to manually trip the turbine / reactor using the same special test procedure used
't in January 1986. This tri resultsasthe1986 trip (pwasperformedonMay1,1987,andhadthesame 8
i.e., plant power was able to be returned to 100%
with greatly reduced OTSG 1evels).
In July 1988, during the 7R refueling outage, a new technique developt:.i by the industry and referred to as " water slap" was employed, resulting in about an t
8% reduction in OTSG 1evels. At about the same time TMI-1 initiated use of morpholine additions to the condensate system to reduce the corrosion rate in.
secondary system components. The plant was able to be operated during the next fuel cycle (8/88 - 1/90) with relatively low 0TSG 1evels and no power restrictions. On the basis of apparent mitigation of the OTSG fouling problem,
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no specific action was taken during the recent BR refueling outage to remove or redistribute OTSG secondary side corrosion products. During power i
escalation after the BR refueling outye, GPUN noted that power level was limited by downcomer level in the "B" OTSG. At that point, being at the very
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begindng of the fuel cycle, GPUN began evaluating options to remove 07
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initigate this limitation.
j On March 6,1990, a tube leak occurred in the "A" OTSG necesritating a
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controlled plant shutdown and cooldown. When the plant was restarted approximately one week later, following repeirs to the "A" OTSG, power was still limited due to *B" OTSG leYGl which Was about 851 at 79% reactor power.
Level in the 'A" OT$R (followIng tube repairr,) at 79% reactor pow;r was 68%
compared to 85% in the 'B' OTSG.
GPUN informed the NRC verbally on March 23 and in a letter on March 30, 1990,-
of their intention to mar.ually trip the THl.1 main turbine on March 30 using i
the same test procedure useo in 1985 and 1987 to try to rectify the OTSG fouling problem. The NRC staff, es before, discouraged this test since it j
places unnecessary challenges on reactor safety systems. The trip was executed on March 30 and resulted in the plant being able to achieve about 98%
1 power before "B" OTSG 1evel became limiting.
In their March 30 letter, GPUN j
suggested a meeting with the NRC staff to discuss all. aspects of the cause of and corrections to the OTSG fouling problem. This was the purpose of the 1
April 20, 1990 meeting.
MEETING DETAILS J
GPUN reviewed the causes and history of OTSG fouling at TMI 1.
A common black iron oxide called magnetite (Fe3,) is fonned in the turbine cycle piping and 1
0 components, including the moisture separators, and transported to the OTSGs, where it deposits on the tubes and tube supports.
In some cases, this material completely bridges the " broached" openings in the tube s@ port alates a
(see Enclosure 2) causing flow restrictions.
In other cases flakes of tiis material spall off the tubos due to cemperature changes and cause blockage-in the broached openings. These phenomenan occur mostly in the lower half of the OTSG due to continuous wettin: ar.d drying in this region (the steam is l
superheatedintheupperregionoftheOTSG). The history of the effects of this fouling at TMI-1, the relative effectiveness of varices mitigative measures (planned trips, water slap, morpholine injection), and the relative success of water slap at several B&W plants since 1985 are shown in tabular form in Enclosure 2.
GPUN has developed a model to predict OTSG 1evel versus time in the fuel cycle based upon past experience. An iron transport study has been used in this study and results during cycle 7 of operation agreed fairly closely with the model.
In addition, GPUN has evaluated and implemented morpholine additions to the secondary system, with a measurable decrease in iron introduction, and has elected to operate with the moisture separation drains lined up to the main k h YE
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GPU Nuclear Corporation P condenser in order to reroute this condensate to the condensate polishers.
i This latter line@ results in an economic penalty. These two measures combined result in a calculated reduction in iron transport into the OTSGs from 238 l
lbs/EFPY to 118 lbs/EFPY.
GPUN discussed various chemical alternatives in minimizing the effects of OTSG l
fouling including chemical cleaning blowdown, new amines, high temperature polishing systems (e.g., in the mosIture separator drains), and boric acid treatnent. The Steam Generator Owners Group (SG0G) chemical cleaning method l
has been selected fcr use at TMI-I and has been scheduled for performance during the 9R refueling outage (late 1991), sending final results of a plant-specific waterials testing program. Tie Geman KWU process was also i
evaluated by GPUN for application at TN1-1. A vendor has been selected for chemicaly cleaning of the TMI-1 OTSGs.
Blowdown as a method to control and remove corrosion products from the OTSGs I
was discussed. Due to the once through nature of flow through OTSGs (i.e., no recirculation), blowdown has been shown ineffective for this pur?ose, particularly above 25% power. To increase the effectiveness of
>10wdowns would require major design changes to the OTSGs and would not be cost effective.
New amines are being pursued as an alternative to ammonia and n.orpholine additions to the secondary system. EPRI is sponsoring testing in this area l
but has not progressed to the point of implementation. GPUN is also l
investigating high temperature polishing systems for application in the moisture separator drain system to remove corrosion products. A final chemical l
alternative discussed was use of boric acid in the OTSG secondary side to I
mitigate / inhibit fouling. Although EPRI has sponsored some research regarding use of boric acid to inhibit denting in recirculating type steam generators, e
no wurk has been done to determine the feasibility to mitigate OTSG fouling.
Although GpVN does not be1Teve it would be effective, the staff believes some research into this nethod may be warranted.
GPUN reviewed the advantages and disadvantages of mechanical alternatives in dealing with OTSG fouling. The most effective mechanical option is the water slap technique previously mentioned. The primary advantages are low relative cost and the effectiveness in removing flake type deposits.. The disadvantages include its ineffectiveness in removing broached hole type deposits, limited availability of contractor personnel and equipment, and the need to shutdown and cool down the plant (if operating at power) for about a two week period of time. GPUN stated that this technique is not a long term solution because it removes little of the corrosion product material, and the level of success cannot be reliably predicted. This technique has been used at four B&W plants, including THI-1, with varying degrees of success. Other mechanical alternatives discussed were magnetic feedwater filters and feedwater heater and piping replacement. The former is relatively ineffective and the latter is prohibitively expensive.
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The first one, continued i
operation at reduced power level, may increase wear of secondary plant equip-ment and may reduce plant stability if power levels are low enough.
It also may result in the plant being operated with the high OTSG main feedwater trip portion of the Heat Sink Protection System being operated in the bypass mode to avoid undesireable plant transients. The second operational alternative is I
a controlled plant trip, such as the one conducted on March 30. GPUN reviewed the special prerequisites and sequence under which this special test is conducted. They also stated that although this is not the preferred alternative for dealing with the fouling problem there may te occasions in the interim period (until OTSG fouling is effectively reduced on a more pennanent basis) that this option is appropriate.
J GPUN's conclusions were as follows:
'GPUN has been proactive in understanding fouling and techniques to mitigate fouling.
'The occurrence and plant impact of fouling is' difficult to anticipate and quantify.
'All options for mitigating fouling have advantages as well as disadvantages
'The effectiveness of each technique for mitigating fouling varies and cannot be fully quantified.
' Controlled plant trips remain a safe, viable technique for temporarily mitigating OTSG bloctage.
'GPUN will select future options based upon continuing evaluations and plant conditions.
l The staff raised one concern in regards to a potential problem that could result from chemical claaning. The concern is that, if tube denting had occurred from buildup of corrosion products and if the corrosion products were dissolved by chemical cleaning, new channels or clearances could be opened up which may allow tube vibration and potential fatigue failure due to crossflow. GPUN stated that no evidence of tube denting has been identified during extensive eddy current testing over the past several years. They i
agreed to verify that statement, however. They also stated that the lower portion of the OTSG w there would be little,here denting would be most likely, is also an area where if any, crossflow due to the design of the OTSG.
Following GPUN's presentation and concluding remarks, the staff did not raise j
any specific safety concerns regarding GPU Nuclear's position and planned j
course of action on the 0TSG fouling problem.
Following discussion of the planned agenda items, members of the staff reviewing GPU Nuclear's Technical Specification Change Request resulting from the March 6 OTSG tube leak event asked a number of questions related to the event. One area of interest was whether any of the actions and decision criteria utilized during the March 6 event should be incorporated into site procedures. Another area of interest was whether note accurate estimates of primary-to-secondary leak rates can be made using different methodologies.
GPU Nuclear stated that some of these issues are being evaluated and the staff I
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5-GPU Nuclear Corporation will be r.ctified of any changes made as a result of the event. The staff reiterated that the NRC considered the response to the liarch 6 tube leak to be timely ard appropriate.
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Ronald W. Hernan, Senior Project Manager Project Directorate 1-4 Division of Reactor Projects
!/11 Office of Nuclear Reactor Regulation
Enclosures:
As stated cc w/ enclosures:
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GPU Nuclear Corporation May 10,1990 will be notified of any changes made as a result of the event. The staff reiterated that the NRC considere' the response to the tiarch 6 tube leak to be timely and appropriate.
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Ronald W. Hernan, Senior Project Manager Project Directorate 1 4 Division of Reactor Projects. 1/11 Office of Nuclear Reactor Regulation
Enclosures:
As stated cc w/enclosurcs:
See next page l
DISTRIBUTION 467 tiRC PDR Local PDR F.141raglia (1?G18)
Plant file S.Varga(14E4)
C. Cheng J. Stolz S. florris R. Mernan B. Boger F. Young L. Miens R. Jones C. ticCracken A. Thadani H. Conrad H. Silver E. Jordan (liNBB 3302)
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Mr. Henry D. Hukill Three Mile Island Nuclear Station, GPU Nuclear Corporation Unit No. 1 i
i CC:
I G. Broughton Francis !. Young 0&M Director TMI.1 SeniorResidentInspector(TM1-1)
GPU Nuclear dorporation U.S.N.R.C.
Post Office Box 480 Post Office Box 311 l
Middletown, Pennsylvania 17057 Middletown, Pennsylvania 17057 Richard J. McGoey l
Manager PWR Licensing Re ional Administrator, Region I GPU Nuclear Corporation U.. Nuclear Regulatory Commission t
i 100 Interpace Parkway 475 Allendale Road i
I Parsippany, New Jersey 07054 King of Prussia, Pennsylvania 19406 C. W. Sg th Robert B. Borsum TMI-1 Licensing Manager Babcock & Wilcox GPU Nuclear Corporation Nuclear Power Gener6 tion Division Post Office Box 480 Suite 525 Middletown, Pennsylvania 17057 1700 Rockville Pike Rockville, Maryland 20852 i
Ernest L. Blaka, Jr., Esq.
Governor's Office of State Planning Shaw, Pittman, Potts & Trowbridge and Development 2300 N Street, N.W.
ATTN: Coordinator, Pennsylvania Washington, D.C.
20037 State Clearinghouse Post Office Box 1323 Harrisburg, Pennsylvania 17120 Sally S. Klein, Chairperson Thomas M. Gerusky, Director I
Dauphin County Comissioner Bureau of Radiation Protection Dauphin County Courthouse Pennsylvania Department of Front and Market Streets Environmental Resources Harrisburg, Pennsylvania 17120 Post Office Box 2063 Harrisburg, Pennsylvania 17120 Kenneth E. Witmer, Chairman Board of Supervisors of Londonderry Township 25 Roslyn Road E112abethtown,PA 17022 t
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l ENCLOSURE I EE_NDEELIST APRIL 20.1990 MEETING WITH GPU NUCLEAR ON TMI 1 OTSG FOULING NAME AFFILIATION Ron Hernan NRC/NRR/PDI A i
Bruce Boger NRC/NRR/ADRI l
F. Young SRI-TMI/RI/NRC Susan Peleschak PA Site representative 9 TMI NRR/PDII Oconee Pli l
Len Wiens Robert Jones NRC/NRR/SRXB Conrad McCracken Nrr/ DST /SPLB l
Ashok Thadani NRR/ DST H. F. Conrad NRR/DET J. F. Stolz NRC/NRR/PDI-4 G. Capodanno GPUN, Director Engineering & Design R. McGoey GPUN, Manager Licensing Hank Hukill GPUN - V.P./Dir. TM1-1 i
J. L. Sullivan, Jr.
GPUN - Licensing / Reg. Affairs J. D. Abramoyici GPUN - Engineering & Design D. C. Shelton Chair BWOG Exec Committee G. L. Lehmann GPUN - Engineering & Deuign R. E. Boyer SR0/Shif t Supervisor El-1 Jack Wetmore GPUtl Frank Paulewicz Plant Engineering, TMI-1 J. H. Taylor B&W Harley Silver NRR CR 3 PM j
Jim Partlow NRC/NRR/ADPR l
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MEETING OBJECTIVES III.
OTSG FOULING 1
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TMI EXPERIENCE o
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MECHANICAL ALTERNATIVES C.
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CHEMICAL ALTERNATIVES A. CURRENTLY BEING EMPLOYED 1.
USE OF MORPH 0LINE CONDUCTED MINI-TEST IN CONJUNCTION WITH EPRI IN 1988 o
IMPLEMENTED MORPH 0LINE USE AT TMI-1 MAY, 1988 o
USE RESULTED IN REDUCED IRON TRANSPORT TO OTSGs o
ESTIMATED MASS OF TOTAL IRON TO OTSG (P0UNDS PER EFPY)
ALL MSD ALL MSD BACK FORWARD T0_ CONDENSER NORMAL CHEMISTRY 238 156 MORPH 0LINE 158 118 CHEMISTRY 2.
MOISTURE SEPARATOR DRAINS (M50s)
ROUTING DRAINS TO CONDENSER ALLOWS IRON REMOVAL o
VIA CONDENSATE POLISHER ALTHOUGH THIS RESULTS IN ECONOMIC PENALTY DUE TO o
LOST BTUs, TMI-1 CURRENTLY RETURNS DRAINS TO CONDENSER 4
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CHEMICAL ALTERNATIVES (CONTINUED)
B.
OTHER ALTERNATIVES f
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CHEMICAL CLEANING METHODS l
GPUN HAS BEEN ACTIVELY EVALUATING CHEMICAL CLEANING METHODS l
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SGOG PROCESS DEVELOPED AS PART OF INDUSTRY FUNDED (EPRI NANAGED) STEAM GENERATOR OWNERS GROUP PROGRAM o
PROCESS USED AT MILLSTONE 2 AND MAINE YANKEE TO CLEAN
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THE TUBE SHEETS o
PROCESS USED AT OCONEE 1 AND 2 TO CLEAN UP TO NINTH TUBE SUPPORT PLATE M
1 o
KWU PROCESS DEVELOPED IN GERMANY o
APPLIED AT EIGHT EUROPEAN NUCLEAR POWER-PLANTS i
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CHEMICAL ALTERNATIVES j
(CONTINUED) i i
i CHRONOLOGY OF GPUN EVALUATIONS
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GPUN PART OF SG0G i
o 1986 - GPUN STARTS EVALUATION OF SG0G PROCESS FOR TMI-1 APPLICATION e
o 1988 - GPUN PURCHASES DUKE FUNDED SGOG QUALIFICATION 1
DATA o
1988 - TMI-1 FLAKES WERE DISSOLUTION TESTED 1
o 1989 - PROCESS SPECIFICATION DEVELOPED FOR-APPLICATION AT TMI-1 I
o 1989 - CONDUCTED DETAILED MATERIALS EVALUATION o
1990 - TMI-1 DISSOLUTION TESTING 0F DEPOSITS WILL BE PERFORMED TO DETERMINE MORPH 0LINE IMPACT ON DISSOLUTION RATE i
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CURRENTLY EVALUATING NEED FOR ADDITIONAL TESTING OF t
MATERIALS U
GRC2/NRC/14 1
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a CHEMICAL ALTERNATIVES (CONTINUED) l t
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GPUN IS MEMBER OF B&WOG STEAM GENERATOR COMMITTEE o
1987 - B&WOG BEGINS EVALUATION i
o 1988 - B&WOG CORR 0SION TESTING OF SELECTED OTSG i
MATERIALS NOT C0VERED IN EARLIER KWU QUALIFICATION
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EFFORTS i
o 1988 - GPUN FUNDED FURTHER MATERIALS TESTING 4
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CHEMICAL ALTERNATIVES (CONTINUED)
STATUS OF TMI-1 CHEMICAL CLEANING o
SGOG PROCESS HAS BEEN SELECTED FOR APPLICATION AT TMI-1 o
VENDOR MAS BEEN SEliCTED o
REMAINING ACTIONS o
FINAL DISSOLUTION TESTING WILL COMMENCE IN 1990 o
ENGINEERING EVALUATION INDICATES ADDITIONAL MATERIALS QUALIFICATION TESTING FOR TMI-1 UNIQUE MATERIALS MAY BE NEEDED FINAL DECISION TO CLEAN IS A FUNCTION OF QUALIFICATION o
RESULTS Aho OTSG PERFORMANCE l
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CHEMICAL ALTERNATIVES (CONTINUED)
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2.
BLOWDOWN i
o BLOWDOWN SYSTEMS NOT EFFECTIVE BECAUSE IMPURITIES DO NOT CONCENTRATE AB0VE ABOUT 25% POWER i
o HIGH FLOW VELOCITY CARRIES MOST OF WHAT ENTERS IN FEEDWATER UP AND OUT IN A SINGLE PASS o
USE OF A BOTTOM DRAIN LINE WAS TRIED BUT FOUND TO BE INEFFECTIVE SINCE DRAIN IS CONNECTED TO DOWNCOMER AREA AT LOWER TUBESHEET o
TO ACHIEVE ANY TYPE OF EFFECTIVE OTSG BLOWDOWN AT LOW POWER WOULD REQUIRE A MAJOR DESIGN CHANGE TO GAIN ACCESS TO THE TUBE BUNDLE AREA o
RECIRCULATING GENERATORS HAVE BLOWDOWN SYSTEMS AND STILL GET SLUDGE' PILES l
3.
NEW AMINES i
o ALTERNATIVES TO AMMONIA AND MORPH 0LINE o
EPRI SPONSORED TESTING IN PROGRESS - NOT READY FOR IMPLEMENTATION i
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HIGH TEMPERATURE POLISHING SYSTEM J
o SOME~ TESTING HAS BEEN CONDUCTEu JE AN OTSG PLANT -
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PART.OF B&WDG ACTIVITIES o
EPRI SPONSORED TESTING MAY. COMMENCE-LATE 1990 o
NOT READY FOR IMPLEMENTATION I
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BORIC ACID TREATMENT I -
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EPRI SPONSORED WORK WITH BORIC ACID TO INHIBIT DENTING OF: TUBE SUPPORT-PLATES IN RECIRCULATING' STEAM GENERATORS l
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NO WORK. CONDUCTED T0 DEMONSTRATE:00RIC ACID CAN I
MITIGATE OTSG FOULING - DO NOT BELIEVE IT WOULD BE i
EFFECTIVE
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MECHANICAL ALTERNATIVE 1 I
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WATER SLAP 1
WHAT I'i WATER SLAP ?
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A PROCESS-DESIGNED TO REMOVE BROACH HOLE DEPOSITS BY USING l
NITROGEN TO CAUSE A WATER SWELL AND " SLAP" EACH SUPPORT PLATE-k ADVANTAGES 1-
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o VERY EFFECTIVE AT DISLODGING FLAKE TYPE DEPOSITS o
PRIOR EXPERIENCE AT TMI-1 AND OTHER OTSGs o
RELATIVELY INEXPENSIVE WHEN COMPARED TO CHEMICAL CLEANING, 8
(APPROXIMATELY $800K VS, $5.5-x 10 )
o OUALIFIED FOR MULTIPLE APPLICATIONS DURING PLANT LIFE DISADVANTAGES o
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'NOT VERY EFFECTIVE IN DISLODGING BROACHED HOLE TYPE DEPOSITS i-o REQUIRES PLANT SHUTDOWN OF APPROXIMATELY TWO WEEKS d
o AVAILABILITY o
REQUIRES CONTRACTOR PERSONNEL TO PERFORM
.o EQUIPMENT IS SHARED BY OTHER UTILITIES o
NOT A LONG TERM SOLUTION f-o LEVEL OF SUCCESS CANNOT BE PREDICTED GRC2/NRC/20
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MECHANICAL ALTERNATIVES WATER SLAP (CONTINUED)
WATER SLAP EXPERIENCE AT OTHER PLANTS o
VARIED DEGREE OF SUCCESS o
POWER RESTORED FROM FEW MONTHS'TO FULL CYCLE o
USED AT FOUR OTSG PLANTS
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PRE-W.S.
POST-W.S.
PLANT DATE POWER LEVEL POWER LEVEL
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ANO-1 1985 84%
94/75 100%
85/72
- 1 rp OC-2 1985 72%
85/92 100%
83/91 CR-3 1985 92%
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88/88 100%
81/81 i
OC-2 1986 100%
85/93 95%
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ANO-1 1986 75%
100/87 100%
86/80 J
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88/81 100%-
79/80 TNI-1 1988 100%-
88/88 100%-
80/80 3
ANO-1 1988 90%
90 100%
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MAGNETIC FILTERS o
LIMITED UTILITY EXPERIENCE o
RETAINS ONLY A FRACTION OF THF. PARTICULATE-IRON
- DOES NOT' TREAT SOLUBLE IRON 3.
FEEDWATER HEATER AND PIPING REPLACEMENT t
o REMOVES CARBON STEEL FROM SYSTEM
.o MAJOR EFFORT AND EXPENSE FEEDWATER CLEAN-UP PRIOR TO PLANT START-UP'AND USE 0F o
MORPH 0LINE MITIGATES IMPACT'0F-CARBON STEEL COMPONENTS ON IRON TRANSPORT i
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OPERATIONAL ALTERNATIVES 1.
OPERATION Af REDUCED POWER o
DOES,NOT. REDUCE.0R ELIMINATE THE PROBLEM.
o MAY INCREASE WEAR OF SECONDARY PLANT EQUIPMENT DUE TO OFF-DESIGN POINT OPERATING CONDITIONS o
INCREASES POWER PRODUCTION COSTS i
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'e OPERATIONAL ALTERNATIVES (CONTINUED) i 1
2.
CONTROLLED PLANT TRIP PREREQUISITES:
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SPECIAL-TEMPORARY PROCEDURE (STP)
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o N0 ONGOING MAINTENANCE ACTIVITIES..
o NO SAFETY RELATED SYSTEMS OUT-OF-SERVICE o
AUXILIARY BOILERS AVAILABLE AND.0PERATING l
.o MANAGEMENT PERSONNEL PRESENT-t o
ADDITIONAL OPERATING / MAINTENANCE / ENGINEERING MANPOWER-TO SUPPORT EV0LUTION o.
PLANT AT STEADY POWER PRIOR TO THE TRIP o
ICS NORMALLY POWERED AND IN AUTOMATIC o
STP RUN ON SIMULATOR o
CREW BRIEFING PRIOR TO'. TRIP I
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u CONTROLLED PLANT TRIP (CONTINUED)
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SEQUENCE:
o TRIP TURBINE /: REACTOR TRIP o
WHEN REACH POST TRIP WINDOW, INITIATE EFW AND RAISE OTSG l
LEVEL 1.
'o WITH STABLE OTSG LEVEL TRIP ALL RC PUMPS o
RESTART RC PUMPS o
RAISE AND LOWER OTSG LEVEL USING EFW o
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CONTROLLED PLANT' TRIP-CONCLUSIONS i
o CONTROLLED TRIP VERSUS UNPLANNED TRIP IS NOT CONTRARY TO-SPIP PHILOSOPHY FOR TRIP REDUCTION EFFORTS
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CONSISTENT WITH OPERATOR TRAINING PHILOSOPHY THAT A TURBINE /RX TRIP IS A SAFE EVOLUTION o'
SIMILAR TO TMI-1 TRIP DURING P.E.T. IN 1985 o
EFFECTIVE MEANS FOR CLEARING FLOW BLOCKAGE DUE TO FLAKES i
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CONCLUSIONS j
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o GPUN.NAS BEEN PROACTIVE IN UNDERSTANDING FOULING AND-TECHNIQUES TO: MITIGATE FOULING
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THE.0CCURRENCE AND PLANT IMPACT OF FOULING IS DIFFICULT-TO ANTICIPATE AND QUANTIFY o
ALL OPTIONS FOR MITIGATING FOULING HAVE ADVANTAGES-AS WELL-AS DISADVANTAGES o
THE EFFECTIVENESS OF EACH TECHNIQUE FOR MITIGATING FOULING 1
VARIES ANO.CANNOT BE FULLY QUANTIFIED 1
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CONTROLLED PLANT TRIPS. REMAIN A SAFE, VIABLE TECHNIQUE FOR l
TEMPORARILY MITIGATING OTSG BLOCKAGE.
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GPUN WILL SELECT FUTURE.0PTIONS BASED ON CONTINUING EVALUATIONS AND PLANT CONDITIONS i
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