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{{#Wiki_filter:IUNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555November 23, 1994NRC INFORMATION NOTICE 94-79:MICROBIOLOGICALLY INFLUENCED CORROSION OFEMERGENCY DIESEL GENERATOR SERVICE WATER PIPING
{{#Wiki_filter:I UNITED STATES NUCLEAR REGULATORY
 
COMMISSION
 
===OFFICE OF NUCLEAR REACTOR REGULATION===
WASHINGTON, D.C. 20555 November 23, 1994 NRC INFORMATION
 
NOTICE 94-79: MICROBIOLOGICALLY
 
INFLUENCED
 
CORROSION
 
OF EMERGENCY
 
DIESEL GENERATOR
 
SERVICE WATER PIPING


==Addressees==
==Addressees==
All holders of operating licenses or construction permits for nuclear powerreactors.PurDoseThe U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert addressees to degradation resulting from microbiologicallyinfluenced corrosion in carbon steel piping systems that supply service waterto emergency diesel generators. It is expected that recipients will reviewthe information for applicability to their facilities and consider actions, asappropriate, to avoid similar problems. However, suggestions contained inthis information notice are not NRC requirements; therefore, no specificaction or written response is required.
All holders of operating
 
licenses or construction
 
permits for nuclear power reactors.PurDose The U.S. Nuclear Regulatory
 
Commission (NRC) is issuing this information
 
notice to alert addressees
 
to degradation
 
resulting
 
from microbiologically
 
influenced
 
corrosion
 
in carbon steel piping systems that supply service water to emergency
 
diesel generators.
 
It is expected that recipients
 
will review the information
 
for applicability
 
to their facilities
 
and consider actions, as appropriate, to avoid similar problems.
 
However, suggestions
 
contained
 
in this information
 
notice are not NRC requirements;  
therefore, no specific action or written response is required.Description
 
of Circumstances
 
Haddam Neck Plant On February 12, 1994, a through-wall
 
leak developed
 
in the service water system supply piping to the "A" emergency
 
diesel generator.
 
The leak occurred in a weld in an area of low flow, where the licensee was doing light surface grinding to prepare for ultrasonic
 
test (UT) inspection.
 
Previously, in March 1993, the licensee had found a similar leak associated
 
with the "B" emergency diesel generator.
 
After removing the leaking section and examining
 
the pipe, the licensee determined
 
that the leak was caused by poor initial weld quality and microbiologically
 
influenced
 
corrosion.
 
Lack of penetration
 
of some welds created a crevice condition.
 
Radiographic
 
tests (RT) of additional
 
emergency diesel generator
 
service water system piping revealed three additional
 
welds that could form similar leaks. It was during preparation
 
of one of these welds for UT examination
 
that the through-wall
 
leak associated
 
with the "A" emergency
 
diesel generator
 
was found.The licensee had previously
 
performed
 
a structural
 
integrity
 
determination
 
in 1993 by radiography.
 
Though based on a uniform wall loss instead of a sharp ,disruption, the licensee had at that time concluded
 
that the worst-case
 
degraded cross-section
 
of the as-found pipe welds, located in the unisolable
 
portions of the emergency
 
diesel generator
 
supply piping, met the Generic Letter 90-05 acceptance
 
criteria for structural
 
integrity
 
and that the degraded piping would have sufficient
 
mechanical
 
and structural
 
integrity
 
to remain operable.
 
&_ r" .in '^*94170C 9411170039 towzl +2ji)K I TE NO-rice H#-14-u1 T4 lII /-
IN 94-79 November 23, 1994 Beaver Valley Power Station. Unit I On May 6, 1994, the licensee found a through-wall
 
leak (an 8 mm [5/16 inch]diameter hole) on the "Al train reactor plant river water system header to the emergency
 
diesel generators.
 
The leak developed
 
on the below-grade
 
portion of the 15-cm [6-inch] diameter A106 Grade B carbon steel piping. The licensee excavated
 
the "A" and 'B" train headers, ultrasonically
 
examined them using the "autoscan" area mapping technique, and found localized
 
pitting to less than minimum required wall thickness
 
in three additional
 
locations
 
along the"A" train piping. The pits were not clustered
 
or closely spaced, but were located along the pipe length between the five and seven o'clock positions.
 
For reference, the nominal pipe wall thickness
 
is 6.4 mm [0.25 inch] and minimum code wall thickness
 
is 1.5 mm [0.06 inch].The licensee evaluated
 
the pitting in accordance
 
with the American Society of Mechanical
 
Engineers (ASME) Code of record. The basis for the localized thinning evaluation
 
was conducted
 
in accordance
 
with industry guidance, EPRI NP-59IISP, "Acceptance
 
Criteria for Structural
 
Evaluation
 
of Erosion-Corrosion
 
Thinning in Carbon Steel Piping." This evaluation
 
was reviewed by personnel in NRR and deemed as an acceptable
 
conservative
 
means of demonstrating
 
ASME Code conformance.
 
The licensee determined
 
microbiologically
 
influenced
 
corrosion
 
to be the cause of the pitting and through-wall
 
leak. The licensee removed a 0.61 m [24 inch] long section of piping to culture and characterize
 
the microbial
 
activity and perform additional
 
ultrasonic
 
testing.The general inside surface of the piping was moderately
 
corroded, with localized
 
pits and tubercles.
 
Cultures from the pits contained
 
sulfur-reducing bacteria and the anaerobic
 
bacteria Clostridium.
 
The tubercle formation
 
was the result of the growth of the iron-oxidizing
 
bacteria Gallionella.
 
Ultrasonic
 
examinations
 
of a heat-affected
 
zone indicated
 
that the weld examined was not subject to preferential
 
microbiologically
 
influenced
 
corrosion
 
attack.Discussion
 
Stagnant or intermittent-flow
 
conditions, as in the case of emergency
 
diesel service water supply headers, are conducive
 
to the growth of microorganisms
 
that can accelerate
 
corrosion
 
rates. Service water supply lines to emergency diesel generators
 
are stagnant because motor-operated
 
isolation
 
valves are normally maintained
 
shut (except during monthly surveillance
 
testing).Crevices such as those in piping welds that lack penetration
 
can enhance microbiologically
 
influenced
 
corrosion
 
attack by giving a place for deposits and, therefore, for the bacteria to collect. Microbial
 
films form when aerobic species, such as iron-oxidizing
 
bacteria, create anaerobic
 
conditions
 
underneath
 
them for microorganisms, such as sulfate-reducing
 
bacteria, to accumulate
 
at the metal surface. Sulfate-reducing
 
bacteria attack the metal surface, produce corrosive
 
chemicals, and cause deep pitting.
 
K>J IN 94-79 November 23, 1994 Microbiologically
 
influenced
 
corrosion
 
on carbon steel will increase general corrosion, through-wall
 
pitting, and the formation
 
of tubercles.
 
Tubercles consist of corrosion
 
products, microbes, and debris. Tubercle growth could restrict cooling water flow to equipment.
 
Stainless
 
steel piping is not immune to microbiologically
 
influenced
 
corrosion because microbes can attack at the weld heat affected zone (HAZ) in stainless steels when this zone becomes sensitized.
 
Microbiologically
 
influenced
 
corrosion
 
can also damage metals lined with polymeric
 
materials, typically
 
at coating imperfections.
 
Once microbial
 
films are established
 
on metal surfaces, they are extremely difficult
 
to eliminate
 
because of the resiliency
 
of the individual
 
microorganisms.
 
Biocides are applied by some licensees
 
in areas where continuous
 
flow conditions
 
cannot be maintained.
 
===However, biocide treatments===
are not always effective
 
against established
 
microorganism
 
colonies because the biocide cannot penetrate
 
through the tubercles
 
or aerobic biofilms.Treatment
 
against established
 
colonies involves a combination
 
of mechanical
 
or chemical pipe cleaning, continued
 
water treatment
 
and regular maintenance.
 
Continuous
 
flow conditions
 
have been found to prevent the attachment
 
and growth of microbial
 
films.It may be necessary
 
to replace materials
 
if microbiologically
 
influenced
 
corrosion
 
severely damages them or where mitigation
 
measures cannot bring the system condition
 
under control. Possible alternatives
 
include replacing carbon steel with stainless
 
steel or replacing
 
stainless
 
steel with more resistant
 
materials, such as 6-percent
 
molybdenum
 
stainless
 
steels, nickel base alloys, titanium, or nonmetallic
 
materials.
 
The licensee did not regularly
 
treat the Beaver Valley River water supply lines to the diesel with biocide or corrosion
 
inhibitors.
 
===The chlorination===
injection
 
point for the main river water headers is downstream
 
of the branch lines to the emergency
 
diesel generators.
 
It also appears that the existing program at Haddam Neck of hypochlorite
 
injection
 
was not successful
 
in mitigating
 
the microbiologically
 
influenced
 
corrosion
 
problems in stagnant dead-end lines at such locations
 
as the emergency
 
diesel generator
 
supply.
 
IN 94-79 November 23, 1994 This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact one of the technical
 
contacts listed below or the appropriate
 
Office of Nuclear Reactor Regulation (NRR) project manager.Vv BaD D ision f Project Support Office of Nuclear Reactor Regulation
 
Technical
 
contacts:
Michael Modes, RI James A. Davis, NRR (215) 337-5198 (301) 504-2713 Peter P. Sena, RI Vern Hodge, NRR (412) 643-2000 (301) 504-1861 Attachment:
List of Recently ssued NRC Information
 
Notices hi It6 J'4 K>Attachment
 
IN 94-79 November 23, 1994 LIST OF RECENTLY ISSUED NRC INFORMATION
 
NOTICES Information
 
Date of Notice No. Subject Issuance Issued to 94-78 94-77 94-76 93-60, Supp. 1 94-75 94-74 94-73 94-72 94-71 Electrical
 
Component Failure due to Degrada-tion of Polyvinyl
 
===Chloride Wire Insulation===
Malfunction
 
in Main Gen-erator Voltage Regulator Causing Overvoltage
 
at Safety-Related
 
Electrical
 
Equipment Recent Failures of Charging/Safety Injection
 
Pump Shafts Reporting
 
Fuel Cycle and Materials
 
Events to the NRC Operations
 
===Center Minimum Temperature===
for Criticality
 
===Facility Management===
Responsibilities
 
for Purchased
 
or Contracted
 
Services for Radiation Therapy Programs Clarification
 
of Critical-ity Reporting
 
Criteria Increased
 
Control Rod Drop Time from Crud Buildup Degradation
 
of Scram Solenoid Pilot Valve Pressure and Exhaust Diaphragms
 
11/21/94 11/17/94 10/26/94 10/20/94 10/14/94 10/13/94 10/12/94 10/05/94 10/04/94 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for pressurized
 
water reactors.All 10 CFR Part 70 fuel cycle licensees.
 
All holders of OLs or CPs pressurized-water
 
reactors (PWRs).All U.S. Nuclear Regulatory
 
Commission
 
Medical Licensees.
 
===All fuel fabrication===
facilities.
 
All holders of OLs or CPs for pressurized
 
water reactors.All holders of OLs or CPs for boiling water reactors (BWRs).OL -Operating
 
License CP = Construction
 
Permit
 
-1/4<> A~-' IN 94-79 November 23, 1994 The licensee did not regularly
 
treat the Beaver Valley River water supply lines to the diesel with biocide or corrosion
 
inhibitors.
 
===The chlorination===
injection
 
point for the main river water headers is downstream
 
of the branch lines to the emergency
 
diesel generators.
 
It also appears that the existing program at Haddam Neck of hypochlorite
 
injection
 
was not successful
 
in mitigating
 
the microbiologically
 
influenced
 
corrosion
 
problems in stagnant dead-end lines at such locations
 
as the emergency
 
diesel generator
 
supply.This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact one of the technical
 
contacts listed below or the appropriate
 
Office of Nuclear Reactor Regulation (NRR) project manager.Original signed by B.D. Liaw for Brian K. Grimes, Director Division of Project Support Office of Nuclear Reactor Regulation
 
Technical
 
contacts: Michael Modes, (215) 337-5198 RI James A. Davis, NRR (301) 504-2713 Peter P. Sena, RI (412) 643-2000 Vern Hodge, NRR (301) 504-1861 Attachment:
List of Recently Issued NRC Information
 
Notices*err DDrFlVT) rnCUriRFNrEN
 
OFFICE *OGCB/DORS
 
*TECH ED *REGION I *REGION I NAME CVHodge JDMain MCModes PPSena DATE J 09/08/94 09/09/94 09/01/94 10/03/94__ _ _ _ _ _ _ _ _ -EI I __ If_*Ann-nfEDrIOTAN
 
T I
 
* FMrR/nF*S:EMCB/DE
 
*C: EMCB/DE , I vv.1,EI *vI __ , --ARBlough JADavis RAHermann
 
===JRStrosnider===
10/03/94 09/20/94 09/20/94-~~~ II f*n. nr*nCrRR /nnP5 I *C AFCBIDOPS I D:DdPWi/Or
 
v.LvL _. -BWSheron RLDennig AEChaffee
 
G& I _J1 10/06/94 10/20/94 10/25/94 1 1 ff_/_ 4 Lj DOCUMENT NAME: 94-79.IN
 
IN 94-XX October xx, 1994 inhibitors.
 
The chlorination
 
injection
 
point for the main river water headers is downstream
 
of the branch lines to the emergency diesel generators.
 
It also appears that the existing program at Haddam Neck of hypochlorite
 
injection
 
was not successful
 
in mitigating
 
the microbiologically
 
influenced
 
corrosion
 
problems in stagnant dead-end lines to such locations
 
as the emergency
 
diesel generator
 
supply.This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact one of the technical
 
contacts listed below or the appropriate
 
Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
contacts:
Michael Modes, Region I (215) 337-5198 Peter P. Sena, Region I (412) 643-2000 James A.Davis, NRR (301) 504-2713 Attachment:
List of Recently Issued NRC Information
 
Notices*SEE PREVIOUS CONCURRENCE
 
OFFICE *OGCB/DORS
 
*TECH ED *REGION I *REGION I NAME CVHodge JDMain MCModes PPSena DATE 09/08/94 j09/09/94
09/01/94 10/03/94._ -11*Ann:DRA/RFCION
 
I I *EMCB/DE I *S:EMCB/DE
 
I *C:EMCB/DE
 
ARBlough JADavis RAHermann
 
===JRStrosnider===
10/03/94 09/20/94 09/20/94 09 94--I -I ~' -7 i*n FOEC 6I1QS I C:994A2'OPS
 
I IWS/NRR BWSheron RLW A af e B j jes 10/06/94 10/9 1,/94 10/ /94 _________DOCUMENT NAME: NECK-MIC.
 
INY
 
-IN 94-XX September
 
xx, 1994 stagnant dead-end lines to such locations
 
as the emergency
 
diesel generator
 
supply.This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact one of the technical
 
contacts listed below or the appropriate
 
Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
contacts: Michael Modes, Region I (215) 337-5198 Peter P. Sena, Region I (412) 643-2000 James A. Davis, NRR (301) 504-2713 Attachment:
List of Recently Issued NRC Information
 
Notices.-- "tf A R'lena-*QVV DPRVUSTnT1 CONCURRENCE
 
--.:L: -a V -__s_ ___ -r- -m --OFFICE *OGCB/DORS
 
*TECH ED *REGION I REGION I A NAME CVHodge I JDMain MCModes PPSena DATE j09/08/94
09/09/94 09/01/94 ff /o3/94_ I ., ._II annlnPq/RFnTON
 
T*EMCB/DE*S: EMCB/DE C;EMCB/DE
 
fir-_ I___ __a _ v_ --ARBlough JADavis RAHermann
 
===LdRStrosnider===
-___ /9 09/20/94 09/20/94 09/X6/94 1~.1 Dkbz AC:OGCB/DORS
 
D:DORS/NRR
 
BW on ELDoolittle
 
BKGrimes__/__ /94 09/ /94 09/ /94 DOCUMgNT NAME: NECK-MIC.1fir
 
A-- 016 I IN 94-XX September
 
xx, 1994 This information
 
notice requires no specific action or written response.
 
If you have any questions
 
about the information
 
in this notice, please contact one of the technical
 
contacts listed below or the appropriate
 
Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
contacts: Michael Modes, Region I (215) 337-5198 Peter P. Sena, Region I (412) 643-2000 James A. Davis, NRR (301) 504-2713 Attachment:
List of Recently Issued NRC Information
 
Notices*SEE PREVIOUS CONCURRENCE
 
--- eIml e .Ac>Iveiw


==Description of Circumstances==
6 2 OFFICE OGCB/DORS
Haddam Neck PlantOn February 12, 1994, a through-wall leak developed in the service watersystem supply piping to the "A" emergency diesel generator. The leak occurredin a weld in an area of low flow, where the licensee was doing light surfacegrinding to prepare for ultrasonic test (UT) inspection. Previously, in March1993, the licensee had found a similar leak associated with the "B" emergencydiesel generator. After removing the leaking section and examining the pipe,the licensee determined that the leak was caused by poor initial weld qualityand microbiologically influenced corrosion. Lack of penetration of some weldscreated a crevice condition. Radiographic tests (RT) of additional emergencydiesel generator service water system piping revealed three additional weldsthat could form similar leaks. It was during preparation of one of thesewelds for UT examination that the through-wall leak associated with the "A"emergency diesel generator was found.The licensee had previously performed a structural integrity determination in1993 by radiography. Though based on a uniform wall loss instead of a sharp,disruption, the licensee had at that time concluded that the worst-casedegraded cross-section of the as-found pipe welds, located in the unisolableportions of the emergency diesel generator supply piping, met the GenericLetter 90-05 acceptance criteria for structural integrity and that thedegraded piping would have sufficient mechanical and structural integrity toremain operable. &_ r" .in '^*94170C9411170039towzl +2ji)K I TE NO-riceH#-14-u1T4 lII /-
IN 94-79November 23, 1994 Beaver Valley Power Station. Unit IOn May 6, 1994, the licensee found a through-wall leak (an 8 mm [5/16 inch]diameter hole) on the "Al train reactor plant river water system header to theemergency diesel generators. The leak developed on the below-grade portion ofthe 15-cm [6-inch] diameter A106 Grade B carbon steel piping. The licenseeexcavated the "A" and 'B" train headers, ultrasonically examined them usingthe "autoscan" area mapping technique, and found localized pitting to lessthan minimum required wall thickness in three additional locations along the"A" train piping. The pits were not clustered or closely spaced, but werelocated along the pipe length between the five and seven o'clock positions.For reference, the nominal pipe wall thickness is 6.4 mm [0.25 inch] andminimum code wall thickness is 1.5 mm [0.06 inch].The licensee evaluated the pitting in accordance with the American Society ofMechanical Engineers (ASME) Code of record. The basis for the localizedthinning evaluation was conducted in accordance with industry guidance, EPRINP-59IISP, "Acceptance Criteria for Structural Evaluation of Erosion-CorrosionThinning in Carbon Steel Piping." This evaluation was reviewed by personnelin NRR and deemed as an acceptable conservative means of demonstrating ASMECode conformance. The licensee determined microbiologically influencedcorrosion to be the cause of the pitting and through-wall leak. The licenseeremoved a 0.61 m [24 inch] long section of piping to culture and characterizethe microbial activity and perform additional ultrasonic testing.The general inside surface of the piping was moderately corroded, withlocalized pits and tubercles. Cultures from the pits contained sulfur-reducing bacteria and the anaerobic bacteria Clostridium. The tubercleformation was the result of the growth of the iron-oxidizing bacteriaGallionella. Ultrasonic examinations of a heat-affected zone indicated thatthe weld examined was not subject to preferential microbiologically influencedcorrosion attack.DiscussionStagnant or intermittent-flow conditions, as in the case of emergency dieselservice water supply headers, are conducive to the growth of microorganismsthat can accelerate corrosion rates. Service water supply lines to emergencydiesel generators are stagnant because motor-operated isolation valves arenormally maintained shut (except during monthly surveillance testing).Crevices such as those in piping welds that lack penetration can enhancemicrobiologically influenced corrosion attack by giving a place for depositsand, therefore, for the bacteria to collect. Microbial films form whenaerobic species, such as iron-oxidizing bacteria, create anaerobic conditionsunderneath them for microorganisms, such as sulfate-reducing bacteria, toaccumulate at the metal surface. Sulfate-reducing bacteria attack the metalsurface, produce corrosive chemicals, and cause deep pitting.


K>J IN 94-79November 23, 1994 Microbiologically influenced corrosion on carbon steel will increase generalcorrosion, through-wall pitting, and the formation of tubercles. Tuberclesconsist of corrosion products, microbes, and debris. Tubercle growth couldrestrict cooling water flow to equipment.Stainless steel piping is not immune to microbiologically influenced corrosionbecause microbes can attack at the weld heat affected zone (HAZ) in stainlesssteels when this zone becomes sensitized. Microbiologically influencedcorrosion can also damage metals lined with polymeric materials, typically atcoating imperfections.Once microbial films are established on metal surfaces, they are extremelydifficult to eliminate because of the resiliency of the individualmicroorganisms. Biocides are applied by some licensees in areas wherecontinuous flow conditions cannot be maintained. However, biocide treatmentsare not always effective against established microorganism colonies becausethe biocide cannot penetrate through the tubercles or aerobic biofilms.Treatment against established colonies involves a combination of mechanical orchemical pipe cleaning, continued water treatment and regular maintenance.Continuous flow conditions have been found to prevent the attachment andgrowth of microbial films.It may be necessary to replace materials if microbiologically influencedcorrosion severely damages them or where mitigation measures cannot bring thesystem condition under control. Possible alternatives include replacingcarbon steel with stainless steel or replacing stainless steel with moreresistant materials, such as 6-percent molybdenum stainless steels, nickelbase alloys, titanium, or nonmetallic materials.The licensee did not regularly treat the Beaver Valley River water supplylines to the diesel with biocide or corrosion inhibitors. The chlorinationinjection point for the main river water headers is downstream of the branchlines to the emergency diesel generators. It also appears that the existingprogram at Haddam Neck of hypochlorite injection was not successful inmitigating the microbiologically influenced corrosion problems in stagnantdead-end lines at such locations as the emergency diesel generator supply.
TECH ED A REGION I REGION I NAME CVHodge k ^JDMain MCModes PPSena DATE 1 O9/08/94 09/09/94 09/01/94 09/ /94 ADD:DRS/REGION


IN 94-79November 23, 1994 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Vv BaDD ision f Project SupportOffice of Nuclear Reactor RegulationTechnical contacts: Michael Modes, RI James A. Davis, NRR(215) 337-5198 (301) 504-2713Peter P. Sena, RI Vern Hodge, NRR(412) 643-2000 (301) 504-1861Attachment:List of Recently ssued NRC Information Noticeshi It6 J'4 K>AttachmentIN 94-79November 23, 1994 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to94-7894-7794-7693-60,Supp. 194-7594-7494-7394-7294-71Electrical ComponentFailure due to Degrada-tion of Polyvinyl ChlorideWire InsulationMalfunction in Main Gen-erator Voltage RegulatorCausing Overvoltage atSafety-Related ElectricalEquipmentRecent Failures of Charging/Safety Injection Pump ShaftsReporting Fuel Cycleand Materials Events tothe NRC Operations CenterMinimum Temperaturefor CriticalityFacility ManagementResponsibilities forPurchased or ContractedServices for RadiationTherapy ProgramsClarification of Critical-ity Reporting CriteriaIncreased Control RodDrop Time from CrudBuildupDegradation of ScramSolenoid Pilot ValvePressure and ExhaustDiaphragms11/21/9411/17/9410/26/9410/20/9410/14/9410/13/9410/12/9410/05/9410/04/94All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor pressurized waterreactors.All 10 CFR Part 70fuel cycle licensees.All holders of OLs or CPspressurized-water reactors(PWRs).All U.S. Nuclear RegulatoryCommission MedicalLicensees.All fuel fabricationfacilities.All holders of OLs or CPsfor pressurized waterreactors.All holders of OLs or CPsfor boiling water reactors(BWRs).OL -Operating LicenseCP = Construction Permit
I EMCB/DE S:EMCB/DF C:EMCB/DE ARBlough JADa RAHermann


-1/4<> A~-' IN 94-79November 23, 1994 The licensee did not regularly treat the Beaver Valley River water supplylines to the diesel with biocide or corrosion inhibitors. The chlorinationinjection point for the main river water headers is downstream of the branchlines to the emergency diesel generators. It also appears that the existingprogram at Haddam Neck of hypochlorite injection was not successful inmitigating the microbiologically influenced corrosion problems in stagnantdead-end lines at such locations as the emergency diesel generator supply.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Original signed by B.D. Liaw forBrian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts:Michael Modes,(215) 337-5198RIJames A. Davis, NRR(301) 504-2713Peter P. Sena, RI(412) 643-2000Vern Hodge, NRR(301) 504-1861Attachment:List of Recently Issued NRC Information Notices*err DDrFlVT) rnCUriRFNrENOFFICE *OGCB/DORS *TECH ED *REGION I *REGION INAME CVHodge JDMain MCModes PPSenaDATE J 09/08/94 09/09/94 09/01/94 10/03/94__ _ _ _ _ _ _ _ _ -EI I __ If_*Ann-nfEDrIOTAN TI
===JRStrosnider===
09/ /94 09/0O/94 09/7v/94 09/ /94 D: DE AC:OGCB/DORS


* FMrR/nF*S:EMCB/DE*C: EMCB/DE, I vv.1,EI *vI __ , --ARBlough JADavis RAHermann JRStrosnider10/03/94 09/20/94 09/20/94-~~~ II f*n. nr*nCrRR /nnP5I *C AFCBIDOPSI D:DdPWi/Orv.LvL _. -BWSheron RLDennig AEChaffee G& I _J110/06/94 10/20/94 10/25/94 1 1 ff_/_ 4 LjDOCUMENT NAME: 94-79.IN
D:DORS/NRR


IN 94-XXOctober xx, 1994 inhibitors. The chlorination injection point for the main riverwater headers is downstream of the branch lines to the emergencydiesel generators. It also appears that the existing program atHaddam Neck of hypochlorite injection was not successful inmitigating the microbiologically influenced corrosion problems instagnant dead-end lines to such locations as the emergency dieselgenerator supply.This information notice requires no specific action or writtenresponse. If you have any questions about the information inthis notice, please contact one of the technical contacts listedbelow or the appropriate Office of Nuclear Reactor Regulation(NRR) project manager.Brian K. Grimes, DirectorDivision of Operating ReactorSupportOffice of Nuclear ReactorRegulationTechnical contacts: Michael Modes, Region I(215) 337-5198Peter P. Sena, Region I(412) 643-2000James A.Davis, NRR(301) 504-2713Attachment: List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCEOFFICE *OGCB/DORS *TECH ED *REGION I *REGION INAME CVHodge JDMain MCModes PPSenaDATE 09/08/94 j09/09/94 09/01/94 10/03/94._ -11*Ann:DRA/RFCION I I *EMCB/DE I *S:EMCB/DE I *C:EMCB/DEARBlough JADavis RAHermann JRStrosnider10/03/94 09/20/94 09/20/94 09 94--I -I ~' -7 i*n FOEC 6I1QS I C:994A2'OPS I IWS/NRRBWSheron RLW A af e B j jes10/06/94 10/9 1,/94 10/ /94 _________DOCUMENT NAME: NECK-MIC. INY
BWSheron ELDoolittle


-IN 94-XXSeptember xx, 1994 stagnant dead-end lines to such locations as the emergency dieselgenerator supply.This information notice requires no specific action or writtenresponse. If you have any questions about the information inthis notice, please contact one of the technical contacts listedbelow or the appropriate Office of Nuclear Reactor Regulation(NRR) project manager.Brian K. Grimes, DirectorDivision of Operating ReactorSupportOffice of Nuclear ReactorRegulationTechnical contacts:Michael Modes, Region I(215) 337-5198Peter P. Sena, Region I(412) 643-2000James A. Davis, NRR(301) 504-2713Attachment: List of Recently Issued NRC Information Notices.-- "tf A R'lena-*QVV DPRVUSTnT1 CONCURRENCE--.:L: -a V -__s_ ___ -r- -m --OFFICE *OGCB/DORS *TECH ED *REGION I REGION I ANAME CVHodge I JDMain MCModes PPSenaDATE j09/08/94 09/09/94 09/01/94 ff /o3/94_ I ., ._IIannlnPq/RFnTON T*EMCB/DE*S: EMCB/DEC;EMCB/DE fir-_ I___ __a _ v_ --ARBlough JADavis RAHermann LdRStrosnider-___ /9 09/20/94 09/20/94 09/X6/941~.1DkbzAC:OGCB/DORSD:DORS/NRRBW on ELDoolittle BKGrimes__/__ /94 09/ /94 09/ /94DOCUMgNT NAME: NECK-MIC.1firA-- 016 IIN 94-XXSeptember xx, 1994 This information notice requires no specific action or writtenresponse. If you have any questions about the information inthis notice, please contact one of the technical contacts listedbelow or the appropriate Office of Nuclear Reactor Regulation(NRR) project manager.Brian K. Grimes, DirectorDivision of Operating ReactorSupportOffice of Nuclear ReactorRegulationTechnical contacts:Michael Modes, Region I(215) 337-5198Peter P. Sena, Region I(412) 643-2000James A. Davis, NRR(301) 504-2713Attachment: List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCE --- eIml e .Ac>Iveiw 6 2OFFICE OGCB/DORS TECH ED A REGION I REGION INAME CVHodge k ^JDMain MCModes PPSenaDATE 1 O9/08/94 09/09/94 09/01/94 09/ /94ADD:DRS/REGION IEMCB/DES:EMCB/DFC:EMCB/DEARBlough JADa RAHermann JRStrosnider09/ /94 09/0O/94 09/7v/94 09/ /94D: DEAC:OGCB/DORSD:DORS/NRRBWSheron ELDoolittle BKGrimes09/ /94 09/ /94 09/ /94DOCU;MENT NAME: NECK-MIC.INF
BKGrimes 09/ /94 09/ /94 09/ /94 DOCU;MENT


}}
NAME: NECK-MIC.INF}}


{{Information notice-Nav}}
{{Information notice-Nav}}

Revision as of 14:00, 31 August 2018

Microbiologically Influenced Corrosion of Emergency Diesel Generator Service Water Piping
ML031060426
Person / Time
Site: Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant  Entergy icon.png
Issue date: 11/23/1994
From: Grimes B K
Office of Nuclear Reactor Regulation
To:
References
IN-94-079, NUDOCS 9411170039
Download: ML031060426 (9)
v • d • e


I UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 November 23, 1994 NRC INFORMATION

NOTICE 94-79: MICROBIOLOGICALLY

INFLUENCED

CORROSION

OF EMERGENCY

DIESEL GENERATOR

SERVICE WATER PIPING

Addressees

All holders of operating

licenses or construction

permits for nuclear power reactors.PurDose The U.S. Nuclear Regulatory

Commission (NRC) is issuing this information

notice to alert addressees

to degradation

resulting

from microbiologically

influenced

corrosion

in carbon steel piping systems that supply service water to emergency

diesel generators.

It is expected that recipients

will review the information

for applicability

to their facilities

and consider actions, as appropriate, to avoid similar problems.

However, suggestions

contained

in this information

notice are not NRC requirements;

therefore, no specific action or written response is required.Description

of Circumstances

Haddam Neck Plant On February 12, 1994, a through-wall

leak developed

in the service water system supply piping to the "A" emergency

diesel generator.

The leak occurred in a weld in an area of low flow, where the licensee was doing light surface grinding to prepare for ultrasonic

test (UT) inspection.

Previously, in March 1993, the licensee had found a similar leak associated

with the "B" emergency diesel generator.

After removing the leaking section and examining

the pipe, the licensee determined

that the leak was caused by poor initial weld quality and microbiologically

influenced

corrosion.

Lack of penetration

of some welds created a crevice condition.

Radiographic

tests (RT) of additional

emergency diesel generator

service water system piping revealed three additional

welds that could form similar leaks. It was during preparation

of one of these welds for UT examination

that the through-wall

leak associated

with the "A" emergency

diesel generator

was found.The licensee had previously

performed

a structural

integrity

determination

in 1993 by radiography.

Though based on a uniform wall loss instead of a sharp ,disruption, the licensee had at that time concluded

that the worst-case

degraded cross-section

of the as-found pipe welds, located in the unisolable

portions of the emergency

diesel generator

supply piping, met the Generic Letter 90-05 acceptance

criteria for structural

integrity

and that the degraded piping would have sufficient

mechanical

and structural

integrity

to remain operable.

&_ r" .in '^*94170C 9411170039 towzl +2ji)K I TE NO-rice H#-14-u1 T4 lII /-

IN 94-79 November 23, 1994 Beaver Valley Power Station. Unit I On May 6, 1994, the licensee found a through-wall

leak (an 8 mm [5/16 inch]diameter hole) on the "Al train reactor plant river water system header to the emergency

diesel generators.

The leak developed

on the below-grade

portion of the 15-cm [6-inch] diameter A106 Grade B carbon steel piping. The licensee excavated

the "A" and 'B" train headers, ultrasonically

examined them using the "autoscan" area mapping technique, and found localized

pitting to less than minimum required wall thickness

in three additional

locations

along the"A" train piping. The pits were not clustered

or closely spaced, but were located along the pipe length between the five and seven o'clock positions.

For reference, the nominal pipe wall thickness

is 6.4 mm [0.25 inch] and minimum code wall thickness

is 1.5 mm [0.06 inch].The licensee evaluated

the pitting in accordance

with the American Society of Mechanical

Engineers (ASME) Code of record. The basis for the localized thinning evaluation

was conducted

in accordance

with industry guidance, EPRI NP-59IISP, "Acceptance

Criteria for Structural

Evaluation

of Erosion-Corrosion

Thinning in Carbon Steel Piping." This evaluation

was reviewed by personnel in NRR and deemed as an acceptable

conservative

means of demonstrating

ASME Code conformance.

The licensee determined

microbiologically

influenced

corrosion

to be the cause of the pitting and through-wall

leak. The licensee removed a 0.61 m [24 inch] long section of piping to culture and characterize

the microbial

activity and perform additional

ultrasonic

testing.The general inside surface of the piping was moderately

corroded, with localized

pits and tubercles.

Cultures from the pits contained

sulfur-reducing bacteria and the anaerobic

bacteria Clostridium.

The tubercle formation

was the result of the growth of the iron-oxidizing

bacteria Gallionella.

Ultrasonic

examinations

of a heat-affected

zone indicated

that the weld examined was not subject to preferential

microbiologically

influenced

corrosion

attack.Discussion

Stagnant or intermittent-flow

conditions, as in the case of emergency

diesel service water supply headers, are conducive

to the growth of microorganisms

that can accelerate

corrosion

rates. Service water supply lines to emergency diesel generators

are stagnant because motor-operated

isolation

valves are normally maintained

shut (except during monthly surveillance

testing).Crevices such as those in piping welds that lack penetration

can enhance microbiologically

influenced

corrosion

attack by giving a place for deposits and, therefore, for the bacteria to collect. Microbial

films form when aerobic species, such as iron-oxidizing

bacteria, create anaerobic

conditions

underneath

them for microorganisms, such as sulfate-reducing

bacteria, to accumulate

at the metal surface. Sulfate-reducing

bacteria attack the metal surface, produce corrosive

chemicals, and cause deep pitting.

K>J IN 94-79 November 23, 1994 Microbiologically

influenced

corrosion

on carbon steel will increase general corrosion, through-wall

pitting, and the formation

of tubercles.

Tubercles consist of corrosion

products, microbes, and debris. Tubercle growth could restrict cooling water flow to equipment.

Stainless

steel piping is not immune to microbiologically

influenced

corrosion because microbes can attack at the weld heat affected zone (HAZ) in stainless steels when this zone becomes sensitized.

Microbiologically

influenced

corrosion

can also damage metals lined with polymeric

materials, typically

at coating imperfections.

Once microbial

films are established

on metal surfaces, they are extremely difficult

to eliminate

because of the resiliency

of the individual

microorganisms.

Biocides are applied by some licensees

in areas where continuous

flow conditions

cannot be maintained.

However, biocide treatments

are not always effective

against established

microorganism

colonies because the biocide cannot penetrate

through the tubercles

or aerobic biofilms.Treatment

against established

colonies involves a combination

of mechanical

or chemical pipe cleaning, continued

water treatment

and regular maintenance.

Continuous

flow conditions

have been found to prevent the attachment

and growth of microbial

films.It may be necessary

to replace materials

if microbiologically

influenced

corrosion

severely damages them or where mitigation

measures cannot bring the system condition

under control. Possible alternatives

include replacing carbon steel with stainless

steel or replacing

stainless

steel with more resistant

materials, such as 6-percent

molybdenum

stainless

steels, nickel base alloys, titanium, or nonmetallic

materials.

The licensee did not regularly

treat the Beaver Valley River water supply lines to the diesel with biocide or corrosion

inhibitors.

The chlorination

injection

point for the main river water headers is downstream

of the branch lines to the emergency

diesel generators.

It also appears that the existing program at Haddam Neck of hypochlorite

injection

was not successful

in mitigating

the microbiologically

influenced

corrosion

problems in stagnant dead-end lines at such locations

as the emergency

diesel generator

supply.

IN 94-79 November 23, 1994 This information

notice requires no specific action or written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project manager.Vv BaD D ision f Project Support Office of Nuclear Reactor Regulation

Technical

contacts:

Michael Modes, RI James A. Davis, NRR (215) 337-5198 (301) 504-2713 Peter P. Sena, RI Vern Hodge, NRR (412) 643-2000 (301) 504-1861 Attachment:

List of Recently ssued NRC Information

Notices hi It6 J'4 K>Attachment

IN 94-79 November 23, 1994 LIST OF RECENTLY ISSUED NRC INFORMATION

NOTICES Information

Date of Notice No. Subject Issuance Issued to 94-78 94-77 94-76 93-60, Supp. 1 94-75 94-74 94-73 94-72 94-71 Electrical

Component Failure due to Degrada-tion of Polyvinyl

Chloride Wire Insulation

Malfunction

in Main Gen-erator Voltage Regulator Causing Overvoltage

at Safety-Related

Electrical

Equipment Recent Failures of Charging/Safety Injection

Pump Shafts Reporting

Fuel Cycle and Materials

Events to the NRC Operations

Center Minimum Temperature

for Criticality

Facility Management

Responsibilities

for Purchased

or Contracted

Services for Radiation Therapy Programs Clarification

of Critical-ity Reporting

Criteria Increased

Control Rod Drop Time from Crud Buildup Degradation

of Scram Solenoid Pilot Valve Pressure and Exhaust Diaphragms

11/21/94 11/17/94 10/26/94 10/20/94 10/14/94 10/13/94 10/12/94 10/05/94 10/04/94 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for pressurized

water reactors.All 10 CFR Part 70 fuel cycle licensees.

All holders of OLs or CPs pressurized-water

reactors (PWRs).All U.S. Nuclear Regulatory

Commission

Medical Licensees.

All fuel fabrication

facilities.

All holders of OLs or CPs for pressurized

water reactors.All holders of OLs or CPs for boiling water reactors (BWRs).OL -Operating

License CP = Construction

Permit

-1/4<> A~-' IN 94-79 November 23, 1994 The licensee did not regularly

treat the Beaver Valley River water supply lines to the diesel with biocide or corrosion

inhibitors.

The chlorination

injection

point for the main river water headers is downstream

of the branch lines to the emergency

diesel generators.

It also appears that the existing program at Haddam Neck of hypochlorite

injection

was not successful

in mitigating

the microbiologically

influenced

corrosion

problems in stagnant dead-end lines at such locations

as the emergency

diesel generator

supply.This information

notice requires no specific action or written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project manager.Original signed by B.D. Liaw for Brian K. Grimes, Director Division of Project Support Office of Nuclear Reactor Regulation

Technical

contacts: Michael Modes, (215) 337-5198 RI James A. Davis, NRR (301) 504-2713 Peter P. Sena, RI (412) 643-2000 Vern Hodge, NRR (301) 504-1861 Attachment:

List of Recently Issued NRC Information

Notices*err DDrFlVT) rnCUriRFNrEN

OFFICE *OGCB/DORS

  • TECH ED *REGION I *REGION I NAME CVHodge JDMain MCModes PPSena DATE J 09/08/94 09/09/94 09/01/94 10/03/94__ _ _ _ _ _ _ _ _ -EI I __ If_*Ann-nfEDrIOTAN

T I

  • FMrR/nF*S:EMCB/DE
  • C: EMCB/DE , I vv.1,EI *vI __ , --ARBlough JADavis RAHermann

JRStrosnider

10/03/94 09/20/94 09/20/94-~~~ II f*n. nr*nCrRR /nnP5 I *C AFCBIDOPS I D:DdPWi/Or

v.LvL _. -BWSheron RLDennig AEChaffee

G& I _J1 10/06/94 10/20/94 10/25/94 1 1 ff_/_ 4 Lj DOCUMENT NAME: 94-79.IN

IN 94-XX October xx, 1994 inhibitors.

The chlorination

injection

point for the main river water headers is downstream

of the branch lines to the emergency diesel generators.

It also appears that the existing program at Haddam Neck of hypochlorite

injection

was not successful

in mitigating

the microbiologically

influenced

corrosion

problems in stagnant dead-end lines to such locations

as the emergency

diesel generator

supply.This information

notice requires no specific action or written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

contacts:

Michael Modes, Region I (215) 337-5198 Peter P. Sena, Region I (412) 643-2000 James A.Davis, NRR (301) 504-2713 Attachment:

List of Recently Issued NRC Information

Notices*SEE PREVIOUS CONCURRENCE

OFFICE *OGCB/DORS

  • TECH ED *REGION I *REGION I NAME CVHodge JDMain MCModes PPSena DATE 09/08/94 j09/09/94

09/01/94 10/03/94._ -11*Ann:DRA/RFCION

I I *EMCB/DE I *S:EMCB/DE

I *C:EMCB/DE

ARBlough JADavis RAHermann

JRStrosnider

10/03/94 09/20/94 09/20/94 09 94--I -I ~' -7 i*n FOEC 6I1QS I C:994A2'OPS

I IWS/NRR BWSheron RLW A af e B j jes 10/06/94 10/9 1,/94 10/ /94 _________DOCUMENT NAME: NECK-MIC.

INY

-IN 94-XX September

xx, 1994 stagnant dead-end lines to such locations

as the emergency

diesel generator

supply.This information

notice requires no specific action or written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

contacts: Michael Modes, Region I (215) 337-5198 Peter P. Sena, Region I (412) 643-2000 James A. Davis, NRR (301) 504-2713 Attachment:

List of Recently Issued NRC Information

Notices.-- "tf A R'lena-*QVV DPRVUSTnT1 CONCURRENCE

--.:L: -a V -__s_ ___ -r- -m --OFFICE *OGCB/DORS

  • TECH ED *REGION I REGION I A NAME CVHodge I JDMain MCModes PPSena DATE j09/08/94

09/09/94 09/01/94 ff /o3/94_ I ., ._II annlnPq/RFnTON

T*EMCB/DE*S: EMCB/DE C;EMCB/DE

fir-_ I___ __a _ v_ --ARBlough JADavis RAHermann

LdRStrosnider

-___ /9 09/20/94 09/20/94 09/X6/94 1~.1 Dkbz AC:OGCB/DORS

D:DORS/NRR

BW on ELDoolittle

BKGrimes__/__ /94 09/ /94 09/ /94 DOCUMgNT NAME: NECK-MIC.1fir

A-- 016 I IN 94-XX September

xx, 1994 This information

notice requires no specific action or written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

contacts: Michael Modes, Region I (215) 337-5198 Peter P. Sena, Region I (412) 643-2000 James A. Davis, NRR (301) 504-2713 Attachment:

List of Recently Issued NRC Information

Notices*SEE PREVIOUS CONCURRENCE

--- eIml e .Ac>Iveiw

6 2 OFFICE OGCB/DORS

TECH ED A REGION I REGION I NAME CVHodge k ^JDMain MCModes PPSena DATE 1 O9/08/94 09/09/94 09/01/94 09/ /94 ADD:DRS/REGION

I EMCB/DE S:EMCB/DF C:EMCB/DE ARBlough JADa RAHermann

JRStrosnider

09/ /94 09/0O/94 09/7v/94 09/ /94 D: DE AC:OGCB/DORS

D:DORS/NRR

BWSheron ELDoolittle

BKGrimes 09/ /94 09/ /94 09/ /94 DOCU;MENT

NAME: NECK-MIC.INF


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