Information Notice 1994-79, Microbiologically Influenced Corrosion of Emergency Diesel Generator Service Water Piping: Difference between revisions

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{{#Wiki_filter:I UNITED STATES NUCLEAR REGULATORY
{{#Wiki_filter:I


COMMISSION
===UNITED STATES===
NUCLEAR REGULATORY COMMISSION


===OFFICE OF NUCLEAR REACTOR REGULATION===
===OFFICE OF NUCLEAR REACTOR REGULATION===
WASHINGTON, D.C. 20555 November 23, 1994 NRC INFORMATION
WASHINGTON, D.C. 20555


NOTICE 94-79: MICROBIOLOGICALLY
===November 23, 1994===
NRC INFORMATION NOTICE 94-79:


INFLUENCED
===MICROBIOLOGICALLY INFLUENCED CORROSION OF===
EMERGENCY DIESEL GENERATOR SERVICE WATER PIPING


CORROSION
==Addressees==
All holders of operating licenses or construction permits for nuclear power


OF EMERGENCY
reactors.


DIESEL GENERATOR
PurDose


SERVICE WATER PIPING
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information


==Addressees==
notice to alert addressees to degradation resulting from microbiologically
All holders of operating


licenses or construction
influenced corrosion in carbon steel piping systems that supply service water


permits for nuclear power reactors.PurDose The U.S. Nuclear Regulatory
to emergency diesel generators.


Commission (NRC) is issuing this information
===It is expected that recipients will review===
the information for applicability to their facilities and consider actions, as


notice to alert addressees
appropriate, to avoid similar problems. However, suggestions contained in


to degradation
this information notice are not NRC requirements; therefore, no specific


resulting
action or written response is required.


from microbiologically
==Description of Circumstances==


influenced
===Haddam Neck Plant===
On February 12, 1994, a through-wall leak developed in the service water


corrosion
system supply piping to the "A" emergency diesel generator. The leak occurred


in carbon steel piping systems that supply service water to emergency
in a weld in an area of low flow, where the licensee was doing light surface


diesel generators.
grinding to prepare for ultrasonic test (UT) inspection.


It is expected that recipients
===Previously, in March===
1993, the licensee had found a similar leak associated with the "B" emergency


will review the information
diesel generator. After removing the leaking section and examining the pipe, the licensee determined that the leak was caused by poor initial weld quality


for applicability
and microbiologically influenced corrosion. Lack of penetration of some welds


to their facilities
created a crevice condition.


and consider actions, as appropriate, to avoid similar problems.
Radiographic tests (RT) of additional emergency


However, suggestions
diesel generator service water system piping revealed three additional welds


contained
that could form similar leaks.


in this information
===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.


notice are not NRC requirements;
The licensee had previously performed a structural integrity determination in
therefore, no specific action or written response is required.Description


of Circumstances
1993 by radiography. Though based on a uniform wall loss instead of a sharp


Haddam Neck Plant On February 12, 1994, a through-wall
,disruption, the licensee had at that time concluded that the worst-case


leak developed
degraded cross-section of the as-found pipe welds, located in the unisolable


in the service water system supply piping to the "A" emergency
portions of the emergency diesel generator supply piping, met the Generic


diesel generator.
Letter 90-05 acceptance criteria for structural integrity and that the


The leak occurred in a weld in an area of low flow, where the licensee was doing light surface grinding to prepare for ultrasonic
degraded piping would have sufficient mechanical and structural integrity to


test (UT) inspection.
remain operable.


Previously, in March 1993, the licensee had found a similar leak associated
&_
r"
.


with the "B" emergency diesel generator.
in '^*
94170C


After removing the leaking section and examining
9411170039 towzl +2ji


the pipe, the licensee determined
)K I TE NO-rice


that the leak was caused by poor initial weld quality and microbiologically
H#-14-u1 T4 lII /-
-"5


influenced
IN 94-79 November 23, 1994 Beaver Valley Power Station. Unit I


corrosion.
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


Lack of penetration
emergency diesel generators. The leak developed on the below-grade portion of


of some welds created a crevice condition.
the 15-cm [6-inch] diameter A106 Grade B carbon steel piping.


Radiographic
===The licensee===
excavated the "A" and 'B" train headers, ultrasonically examined them using


tests (RT) of additional
the "autoscan" area mapping technique, and found localized pitting to less


emergency diesel generator
than minimum required wall thickness in three additional locations along the


service water system piping revealed three additional
"A" train piping.


welds that could form similar leaks. It was during preparation
The pits were not clustered or closely spaced, but were


of one of these welds for UT examination
located along the pipe length between the five and seven o'clock positions.


that the through-wall
For reference, the nominal pipe wall thickness is 6.4 mm [0.25 inch] and


leak associated
minimum code wall thickness is 1.5 mm [0.06 inch].


with the "A" emergency
The licensee evaluated the pitting in accordance with the American Society of


diesel generator
Mechanical Engineers (ASME) Code of record.


was found.The licensee had previously
===The basis for the localized===
thinning evaluation was conducted in accordance with industry guidance, EPRI


performed
NP-59IISP, "Acceptance Criteria for Structural Evaluation of Erosion-Corrosion


a structural
Thinning in Carbon Steel Piping." This evaluation was reviewed by personnel


integrity
in NRR and deemed as an acceptable conservative means of demonstrating ASME


determination
Code conformance. The licensee determined microbiologically influenced


in 1993 by radiography.
corrosion to be the cause of the pitting and through-wall leak. The licensee


Though based on a uniform wall loss instead of a sharp ,disruption, the licensee had at that time concluded
removed a 0.61 m [24 inch] long section of piping to culture and characterize


that the worst-case
the microbial activity and perform additional ultrasonic testing.


degraded cross-section
The general inside surface of the piping was moderately corroded, with


of the as-found pipe welds, located in the unisolable
localized pits and tubercles. Cultures from the pits contained sulfur- reducing bacteria and the anaerobic bacteria Clostridium. The tubercle


portions of the emergency
formation was the result of the growth of the iron-oxidizing bacteria


diesel generator
Gallionella. Ultrasonic examinations of a heat-affected zone indicated that


supply piping, met the Generic Letter 90-05 acceptance
the weld examined was not subject to preferential microbiologically influenced


criteria for structural
corrosion attack.


integrity
Discussion


and that the degraded piping would have sufficient
Stagnant or intermittent-flow conditions, as in the case of emergency diesel


mechanical
service water supply headers, are conducive to the growth of microorganisms


and structural
that can accelerate corrosion rates. Service water supply lines to emergency


integrity
diesel generators are stagnant because motor-operated isolation valves are


to remain operable.
normally maintained shut (except during monthly surveillance testing).


&_ r" .in '^*94170C 9411170039 towzl +2ji)K I TE NO-rice H#-14-u1 T4 lII /-
Crevices such as those in piping welds that lack penetration can enhance
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
microbiologically influenced corrosion attack by giving a place for deposits


diesel generators.
and, therefore, for the bacteria to collect. Microbial films form when


The leak developed
aerobic species, such as iron-oxidizing bacteria, create anaerobic conditions


on the below-grade
underneath them for microorganisms, such as sulfate-reducing bacteria, to


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


the "A" and 'B" train headers, ultrasonically
Sulfate-reducing bacteria attack the metal


examined them using the "autoscan" area mapping technique, and found localized
surface, produce corrosive chemicals, and cause deep pitting.


pitting to less than minimum required wall thickness
K>J


in three additional
IN 94-79 November 23, 1994 Microbiologically influenced corrosion on carbon steel will increase general


locations
corrosion, through-wall pitting, and the formation of tubercles. Tubercles


along the"A" train piping. The pits were not clustered
consist of corrosion products, microbes, and debris. Tubercle growth could


or closely spaced, but were located along the pipe length between the five and seven o'clock positions.
restrict cooling water flow to equipment.


For reference, the nominal pipe wall thickness
Stainless steel piping is not immune to microbiologically influenced corrosion


is 6.4 mm [0.25 inch] and minimum code wall thickness
because microbes can attack at the weld heat affected zone (HAZ) in stainless


is 1.5 mm [0.06 inch].The licensee evaluated
steels when this zone becomes sensitized. Microbiologically influenced


the pitting in accordance
corrosion can also damage metals lined with polymeric materials, typically at


with the American Society of Mechanical
coating imperfections.


Engineers (ASME) Code of record. The basis for the localized thinning evaluation
Once microbial films are established on metal surfaces, they are extremely


was conducted
difficult to eliminate because of the resiliency of the individual


in accordance
microorganisms. Biocides are applied by some licensees in areas where


with industry guidance, EPRI NP-59IISP, "Acceptance
continuous flow conditions cannot be maintained. However, biocide treatments


Criteria for Structural
are not always effective against established microorganism colonies because


Evaluation
the biocide cannot penetrate through the tubercles or aerobic biofilms.


of Erosion-Corrosion
Treatment against established colonies involves a combination of mechanical or


Thinning in Carbon Steel Piping." This evaluation
chemical pipe cleaning, continued water treatment and regular maintenance.


was reviewed by personnel in NRR and deemed as an acceptable
Continuous flow conditions have been found to prevent the attachment and


conservative
growth of microbial films.


means of demonstrating
It may be necessary to replace materials if microbiologically influenced


ASME Code conformance.
corrosion severely damages them or where mitigation measures cannot bring the


The licensee determined
system condition under control.


microbiologically
===Possible alternatives include replacing===
carbon steel with stainless steel or replacing stainless steel with more


influenced
resistant materials, such as 6-percent molybdenum stainless steels, nickel


corrosion
base alloys, titanium, or nonmetallic materials.


to be the cause of the pitting and through-wall
The licensee did not regularly treat the Beaver Valley River water supply


leak. The licensee removed a 0.61 m [24 inch] long section of piping to culture and characterize
lines to the diesel with biocide or corrosion inhibitors. The chlorination


the microbial
injection point for the main river water headers is downstream of the branch


activity and perform additional
lines to the emergency diesel generators. It also appears that the existing


ultrasonic
program at Haddam Neck of hypochlorite injection was not successful in


testing.The general inside surface of the piping was moderately
mitigating the microbiologically influenced corrosion problems in stagnant


corroded, with localized
dead-end lines at such locations as the emergency diesel generator supply.


pits and tubercles.
IN 94-79 November 23, 1994 This information notice requires no specific action or written response. If


Cultures from the pits contained
you have any questions about the information in this notice, please contact


sulfur-reducing bacteria and the anaerobic
one of the technical contacts listed below or the appropriate Office of


bacteria Clostridium.
Nuclear Reactor Regulation (NRR) project manager.


The tubercle formation
Vv BaD


was the result of the growth of the iron-oxidizing
===D ision f Project Support===
Office of Nuclear Reactor Regulation


bacteria Gallionella.
Technical contacts: Michael Modes, RI


Ultrasonic
===James A. Davis, NRR===
(215) 337-5198
(301) 504-2713 Peter P. Sena, RI


examinations
===Vern Hodge, NRR===
(412) 643-2000
(301) 504-1861 Attachment:


of a heat-affected
===List of Recently ssued NRC Information Notices===
hi


zone indicated
It6 J'4


that the weld examined was not subject to preferential
K>
Attachment


microbiologically
IN 94-79


influenced
===November 23, 1994 LIST OF RECENTLY ISSUED===
NRC INFORMATION NOTICES


corrosion
Information


attack.Discussion
Date of


Stagnant or intermittent-flow
Notice No.


conditions, as in the case of emergency
Subject


diesel service water supply headers, are conducive
Issuance


to the growth of microorganisms
Issued to


that can accelerate
94-78
94-77
94-76
93-60,
Supp. 1
94-75
94-74
94-73
94-72
94-71


corrosion
===Electrical Component===
Failure due to Degrada- tion of Polyvinyl Chloride


rates. Service water supply lines to emergency diesel generators
===Wire Insulation===
Malfunction in Main Gen- erator Voltage Regulator


are stagnant because motor-operated
===Causing Overvoltage at===
Safety-Related Electrical


isolation
Equipment


valves are normally maintained
Recent Failures of Charging/


shut (except during monthly surveillance
===Safety Injection Pump Shafts===
Reporting Fuel Cycle


testing).Crevices such as those in piping welds that lack penetration
and Materials Events to


can enhance microbiologically
the NRC Operations Center


influenced
===Minimum Temperature===
for Criticality


corrosion
===Facility Management===
Responsibilities for


attack by giving a place for deposits and, therefore, for the bacteria to collect. Microbial
===Purchased or Contracted===
Services for Radiation


films form when aerobic species, such as iron-oxidizing
===Therapy Programs===
Clarification of Critical- ity Reporting Criteria


bacteria, create anaerobic
===Increased Control Rod===
Drop Time from Crud


conditions
Buildup


underneath
===Degradation of Scram===
Solenoid Pilot Valve


them for microorganisms, such as sulfate-reducing
===Pressure and Exhaust===
Diaphragms


bacteria, to accumulate
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


at the metal surface. Sulfate-reducing
===All holders of OLs or CPs===
for nuclear power reactors.


bacteria attack the metal surface, produce corrosive
===All holders of OLs or CPs===
for nuclear power reactors.


chemicals, and cause deep pitting.
===All holders of OLs or CPs===
for pressurized water


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


influenced
===All 10 CFR Part 70===
fuel cycle licensees.


corrosion
===All holders of OLs or CPs===
pressurized-water reactors


on carbon steel will increase general corrosion, through-wall
(PWRs).


pitting, and the formation
===All U.S. Nuclear Regulatory===
Commission Medical


of tubercles.
Licensees.


Tubercles consist of corrosion
===All fuel fabrication===
facilities.


products, microbes, and debris. Tubercle growth could restrict cooling water flow to equipment.
===All holders of OLs or CPs===
for pressurized water


Stainless
reactors.


steel piping is not immune to microbiologically
===All holders of OLs or CPs===
for boiling water reactors


influenced
(BWRs).


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


Microbiologically
CP = Construction Permit


influenced
-
1/4<>
A~-'
IN 94-79 November 23, 1994 The licensee did not regularly treat the Beaver Valley River water supply


corrosion
lines to the diesel with biocide or corrosion inhibitors. The chlorination


can also damage metals lined with polymeric
injection point for the main river water headers is downstream of the branch


materials, typically
lines to the emergency diesel generators.


at coating imperfections.
===It also appears that the existing===
program at Haddam Neck of hypochlorite injection was not successful in


Once microbial
mitigating the microbiologically influenced corrosion problems in stagnant


films are established
dead-end lines at such locations as the emergency diesel generator supply.


on metal surfaces, they are extremely difficult
This information notice requires no specific action or written response.


to eliminate
If


because of the resiliency
you have any questions about the information in this notice, please contact


of the individual
one of the technical contacts listed below or the appropriate Office of


microorganisms.
Nuclear Reactor Regulation (NRR) project manager.


Biocides are applied by some licensees
===Original signed by B.D. Liaw for===
Brian K. Grimes, Director


in areas where continuous
===Division of Project Support===
Office of Nuclear Reactor Regulation


flow conditions
Technical contacts:
Michael Modes,
(215) 337-5198 RI


cannot be maintained.
===James A. Davis, NRR===
(301) 504-2713


===However, biocide treatments===
===Peter P. Sena, RI===
are not always effective
(412) 643-2000


against established
===Vern Hodge, NRR===
(301) 504-1861 Attachment:


microorganism
===List of Recently Issued NRC Information Notices===
*err DDrFlVT)
rnCUriRFNrEN


colonies because the biocide cannot penetrate
OFFICE


through the tubercles
*OGCB/DORS


or aerobic biofilms.Treatment
*TECH ED


against established
*REGION I


colonies involves a combination
*REGION I


of mechanical
NAME


or chemical pipe cleaning, continued
CVHodge


water treatment
JDMain


and regular maintenance.
MCModes


Continuous
PPSena


flow conditions
DATE


have been found to prevent the attachment
J


and growth of microbial
09/08/94
09/09/94
09/01/94
10/03/94
__
_
_
_
_
_
_
_
_ -EI


films.It may be necessary
I


to replace materials
__
If_
*Ann-nfEDrIOTAN T


if microbiologically
I


influenced
* FMrR/nF


corrosion
*S:EMCB/DE


severely damages them or where mitigation
*C: EMCB/DE


measures cannot bring the system condition
,
I


under control. Possible alternatives
vv.1,EI


include replacing carbon steel with stainless
*vI


steel or replacing
__
,
- -
ARBlough


stainless
JADavis


steel with more resistant
RAHermann


materials, such as 6-percent
===JRStrosnider===
10/03/94
09/20/94
09/20/94
-~~~
II


molybdenum
f


stainless
*n. nr


steels, nickel base alloys, titanium, or nonmetallic
*nCrRR /nnP5 I *C AFCBIDOPS


materials.
I D:DdPWi/Or


The licensee did not regularly
v.LvL


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


inhibitors.
-
BWSheron


===The chlorination===
RLDennig
injection


point for the main river water headers is downstream
AEChaffee


of the branch lines to the emergency
G&
I _J1
10/06/94
10/20/94
10/25/94
1 1 ff_/_ 4 Lj


diesel generators.
DOCUMENT NAME:
94-79.IN


It also appears that the existing program at Haddam Neck of hypochlorite
IN 94-XX


injection
October xx, 1994 inhibitors.


was not successful
===The chlorination injection point for the main river===
water headers is downstream of the branch lines to the emergency


in mitigating
diesel generators.


the microbiologically
===It also appears that the existing program at===
Haddam Neck of hypochlorite injection was not successful in


influenced
mitigating the microbiologically influenced corrosion problems in


corrosion
stagnant dead-end lines to such locations as the emergency diesel


problems in stagnant dead-end lines at such locations
generator supply.


as the emergency
This information notice requires no specific action or written


diesel generator
response.


supply.
===If you have any questions about the information in===
this notice, please contact one of the technical contacts listed


IN 94-79 November 23, 1994 This information
below or the appropriate Office of Nuclear Reactor Regulation


notice requires no specific action or written response.
(NRR) project manager.


If you have any questions
===Brian K. Grimes, Director===
Division of Operating Reactor


about the information
Support


in this notice, please contact one of the technical
===Office of Nuclear Reactor===
Regulation


contacts listed below or the appropriate
Technical contacts:


Office of Nuclear Reactor Regulation (NRR) project manager.Vv BaD D ision f Project Support Office of Nuclear Reactor Regulation
===Michael Modes, Region I===
(215) 337-5198


Technical
===Peter P. Sena, Region I===
(412) 643-2000


contacts:
===James A.Davis, NRR===
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:
(301) 504-2713 Attachment:  
List of Recently ssued NRC Information


Notices hi It6 J'4 K>Attachment
===List of Recently Issued NRC Information Notices===
*SEE PREVIOUS CONCURRENCE


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


NOTICES Information
*OGCB/DORS


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
*TECH ED


Component Failure due to Degrada-tion of Polyvinyl
*REGION I


===Chloride Wire Insulation===
*REGION I
Malfunction


in Main Gen-erator Voltage Regulator Causing Overvoltage
NAME


at Safety-Related
CVHodge


Electrical
JDMain


Equipment Recent Failures of Charging/Safety Injection
MCModes


Pump Shafts Reporting
PPSena


Fuel Cycle and Materials
DATE


Events to the NRC Operations
09/08/94 j09/09/94
09/01/94
10/03/94
.


===Center Minimum Temperature===
_
for Criticality
-11
*Ann:DRA/RFCION I


===Facility Management===
I *EMCB/DE I *S:EMCB/DE I *C:EMCB/DE
Responsibilities


for Purchased
ARBlough


or Contracted
JADavis


Services for Radiation Therapy Programs Clarification
RAHermann


of Critical-ity Reporting
===JRStrosnider===
10/03/94
09/20/94
09/20/94
09
94
-
-
I


Criteria Increased
-
I ~'
- 7 i


Control Rod Drop Time from Crud Buildup Degradation
*n


of Scram Solenoid Pilot Valve Pressure and Exhaust Diaphragms
FOEC


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
6I1QS


water reactors.All 10 CFR Part 70 fuel cycle licensees.
I C:994A2'OPS I IWS/NRR


All holders of OLs or CPs pressurized-water
BWSheron


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


Commission
A


Medical Licensees.
af


===All fuel fabrication===
e
facilities.


All holders of OLs or CPs for pressurized
B


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


License CP = Construction
jes


Permit
10/06/94
10/9
1,/94
10/
/94
________
_DOCUMENT NAME:
NECK-MIC.


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


treat the Beaver Valley River water supply lines to the diesel with biocide or corrosion
-
IN 94-XX


inhibitors.
September xx, 1994 stagnant dead-end lines to such locations as the emergency diesel


===The chlorination===
generator supply.
injection


point for the main river water headers is downstream
This information notice requires no specific action or written


of the branch lines to the emergency
response.


diesel generators.
===If you have any questions about the information in===
this notice, please contact one of the technical contacts listed


It also appears that the existing program at Haddam Neck of hypochlorite
below or the appropriate Office of Nuclear Reactor Regulation


injection
(NRR) project manager.


was not successful
===Brian K. Grimes, Director===
Division of Operating Reactor


in mitigating
Support


the microbiologically
===Office of Nuclear Reactor===
Regulation


influenced
Technical contacts:


corrosion
===Michael Modes, Region I===
(215) 337-5198


problems in stagnant dead-end lines at such locations
===Peter P. Sena, Region I===
(412) 643-2000


as the emergency
===James A. Davis, NRR===
(301) 504-2713 Attachment:


diesel generator
===List of Recently Issued NRC Information Notices===
.--
"tf A R'lena-
*QVV


supply.This information
DPRVUSTnT1 CONCURRENCE


notice requires no specific action or written response.
-
-.


If you have any questions
:L:
-a


about the information
V


in this notice, please contact one of the technical
-
__s_
___
-r-
-
m --
OFFICE


contacts listed below or the appropriate
*OGCB/DORS


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
*TECH ED


Technical
*REGION I


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:
REGION I A
List of Recently Issued NRC Information


Notices*err DDrFlVT) rnCUriRFNrEN
NAME


OFFICE *OGCB/DORS
CVHodge


*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
I JDMain


T I
MCModes


* FMrR/nF*S:EMCB/DE
PPSena


*C: EMCB/DE , I vv.1,EI *vI __ , --ARBlough JADavis RAHermann
DATE


===JRStrosnider===
j09/08/94  
10/03/94 09/20/94 09/20/94-~~~ II f*n. nr*nCrRR /nnP5 I *C AFCBIDOPS I D:DdPWi/Or
09/09/94  
09/01/94 ff /o3/94
_
I


v.LvL _. -BWSheron RLDennig AEChaffee
.,
._II


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


IN 94-XX October xx, 1994 inhibitors.
*EMCB/DE


The chlorination
*S: EMCB/DE


injection
C;EMCB/DE fir


point for the main river water headers is downstream
-_
I___
__a


of the branch lines to the emergency diesel generators.
_
v_
--
ARBlough


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


injection
===RAHermann LdRStrosnider===
-___
/9
09/20/94
09/20/94
09/X6/94
1~.1 Dkbz


was not successful
AC:OGCB/DORS


in mitigating
D:DORS/NRR


the microbiologically
BW


influenced
on


corrosion
ELDoolittle


problems in stagnant dead-end lines to such locations
BKGrimes


as the emergency
__/__
/94
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diesel generator
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I


notice requires no specific action or written response.
IN 94-XX


If you have any questions
September xx, 1994 This information notice requires no specific action or written


about the information
response.


in this notice, please contact one of the technical
===If you have any questions about the information in===
this notice, please contact one of the technical contacts listed


contacts listed below or the appropriate
below or the appropriate Office of Nuclear Reactor Regulation


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


===Reactor Support Office of Nuclear Reactor Regulation===
===Brian K. Grimes, Director===
Technical
Division of Operating Reactor


contacts:
Support
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 of Nuclear Reactor===
Regulation


OFFICE *OGCB/DORS
Technical contacts:


*TECH ED *REGION I *REGION I NAME CVHodge JDMain MCModes PPSena DATE 09/08/94 j09/09/94
===Michael Modes, Region I===
09/01/94 10/03/94._ -11*Ann:DRA/RFCION
(215) 337-5198


I I *EMCB/DE I *S:EMCB/DE
===Peter P. Sena, Region I===
(412) 643-2000


I *C:EMCB/DE
===James A. Davis, NRR===
(301) 504-2713 Attachment:  


ARBlough JADavis RAHermann
===List of Recently Issued NRC Information Notices===
*SEE PREVIOUS CONCURRENCE


===JRStrosnider===
---  
10/03/94 09/20/94 09/20/94 09 94--I -I ~' -7 i*n FOEC 6I1QS I C:994A2'OPS
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-IN 94-XX September
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xx, 1994 stagnant dead-end lines to such locations
TECH ED A


as the emergency
REGION I


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supply.This information
NAME


notice requires no specific action or written response.
CVHodge k


If you have any questions
^JDMain


about the information
MCModes


in this notice, please contact one of the technical
PPSena


contacts listed below or the appropriate
DATE


Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
1 O9/08/94
09/09/94
09/01/94
09/
/94 ADD:DRS/REGION I


===Reactor Support Office of Nuclear Reactor Regulation===
EMCB/DE
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:
S:EMCB/DF
List of Recently Issued NRC Information


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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
ELDoolittle


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


NAME: NECK-MIC.INF}}
09/
/94
09/
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09/
/94 DOCU;MENT NAME:  
NECK-MIC.INF}}


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

Latest revision as of 10:49, 16 January 2025

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, 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, Crane  
Issue date: 11/23/1994
From: Grimes B
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.

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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

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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

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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

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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

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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

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