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


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


NOTICE 94-79: MICROBIOLOGICALLY
OFFICE OF NUCLEAR REACTOR REGULATION


INFLUENCED
WASHINGTON, D.C. 20555 November 23, 1994 NRC INFORMATION NOTICE 94-79:    MICROBIOLOGICALLY INFLUENCED CORROSION OF


CORROSION
EMERGENCY DIESEL GENERATOR SERVICE WATER PIPING
 
OF EMERGENCY
 
DIESEL GENERATOR
 
SERVICE WATER PIPING


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


the pitting in accordance
reactors.


with the American Society of Mechanical
PurDose


Engineers (ASME) Code of record. The basis for the localized thinning evaluation
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information


was conducted
notice to alert addressees to degradation resulting from microbiologically


in accordance
service water


with industry guidance, EPRI NP-59IISP, "Acceptance
influenced corrosion in carbon steel piping systems that supply will review


Criteria for Structural
to emergency diesel generators. It is expected that recipients          actions, as


Evaluation
the information for applicability to their facilities and consider              in


of Erosion-Corrosion
appropriate, to avoid similar problems. However, suggestions      contained


Thinning in Carbon Steel Piping." This evaluation
specific


was reviewed by personnel in NRR and deemed as an acceptable
this information notice are not NRC requirements; therefore, no


conservative
action or written response is required.


means of demonstrating
==Description of Circumstances==


ASME Code conformance.
===Haddam Neck Plant===
                                                                        water


The licensee determined
On February 12, 1994, a through-wall leak developed in the serviceleak occurred


microbiologically
system supply piping to the "A" emergency diesel generator.      The


influenced
light surface


corrosion
in a weld in an area of low flow, where the licensee was doing              in March


to be the cause of the pitting and through-wall
grinding to prepare for ultrasonic test (UT) inspection.    Previously, with  the "B"  emergency


leak. The licensee removed a 0.61 m [24 inch] long section of piping to culture and characterize
1993, the licensee had found a similar leak associated                    the pipe, diesel generator. After removing the leaking section and examining    weld  quality


the microbial
the licensee determined that the leak was caused by poor    initial


activity and perform additional
of  some  welds


ultrasonic
and microbiologically influenced corrosion. Lack of penetration          emergency


testing.The general inside surface of the piping was moderately
created a crevice condition. Radiographic tests (RT) of     additional


corroded, with localized
welds


pits and tubercles.
diesel generator service water system piping revealed three additionalof  these


Cultures from the pits contained
that could form similar leaks. It was during preparation    of  one


sulfur-reducing bacteria and the anaerobic
the "A"
welds for UT examination that the through-wall leak associated with


bacteria Clostridium.
emergency diesel generator was found.


The tubercle formation
in


was the result of the growth of the iron-oxidizing
The licensee had previously performed a structural integrity determination


bacteria Gallionella.
of  a sharp


Ultrasonic
1993 by radiography. Though based on a uniform wall    loss  instead


examinations
,disruption, the licensee had at that time concluded that the worst-case unisolable


of a heat-affected
degraded cross-section of the as-found pipe welds, located in the Generic


zone indicated
portions of the emergency diesel generator supply piping,    met  the


that the weld examined was not subject to preferential
that the


microbiologically
Letter 90-05 acceptance criteria for structural integrity and        integrity to


influenced
degraded piping would have sufficient mechanical and structural


corrosion
remain operable.            &_                    r"                          .


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


Stagnant or intermittent-flow
-"5


conditions, as in the case of emergency
IN 94-79 November 23, 1994 Beaver Valley Power Station. Unit I


diesel service water supply headers, are conducive
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


to the growth of microorganisms
emergency diesel generators. The leak developed on the below-grade portion of


that can accelerate
the 15-cm [6-inch] diameter A106 Grade B carbon steel piping. The licensee


corrosion
excavated the "A" and 'B" train headers, ultrasonically examined them using


rates. Service water supply lines to emergency diesel generators
the "autoscan" area mapping technique, and found localized pitting to less


are stagnant because motor-operated
than minimum required wall thickness in three additional locations along the


isolation
"A" train piping. The pits were not clustered or closely spaced, but were


valves are normally maintained
located along the pipe length between the five and seven o'clock positions.


shut (except during monthly surveillance
For reference, the nominal pipe wall thickness is 6.4 mm [0.25 inch] and


testing).Crevices such as those in piping welds that lack penetration
minimum code wall thickness is 1.5 mm [0.06 inch].


can enhance microbiologically
The licensee evaluated the pitting in accordance with the American Society of


influenced
Mechanical Engineers (ASME) Code of record. The basis for the localized


corrosion
thinning evaluation was conducted in accordance with industry guidance, EPRI


attack by giving a place for deposits and, therefore, for the bacteria to collect. Microbial
NP-59IISP, "Acceptance Criteria for Structural Evaluation of Erosion-Corrosion


films form when aerobic species, such as iron-oxidizing
Thinning in Carbon Steel Piping." This evaluation was reviewed by personnel


bacteria, create anaerobic
in NRR and deemed as an acceptable conservative means of demonstrating ASME


conditions
Code conformance. The licensee determined microbiologically influenced


underneath
corrosion to be the cause of the pitting and through-wall leak. The licensee


them for microorganisms, such as sulfate-reducing
removed a 0.61 m [24 inch] long section of piping to culture and characterize


bacteria, to accumulate
the microbial activity and perform additional ultrasonic testing.


at the metal surface. Sulfate-reducing
The general inside surface of the piping was moderately corroded, with


bacteria attack the metal surface, produce corrosive
localized pits and tubercles. Cultures from the pits contained sulfur- reducing bacteria and the anaerobic bacteria Clostridium. The tubercle


chemicals, and cause deep pitting.
formation was the result of the growth of the iron-oxidizing bacteria


K>J IN 94-79 November 23, 1994 Microbiologically
Gallionella. Ultrasonic examinations of a heat-affected zone indicated that


influenced
the weld examined was not subject to preferential microbiologically influenced


corrosion
corrosion attack.


on carbon steel will increase general corrosion, through-wall
Discussion


pitting, and the formation
Stagnant or intermittent-flow conditions, as in the case of emergency diesel


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


Tubercles consist of corrosion
that can accelerate corrosion rates. Service water supply lines to emergency


products, microbes, and debris. Tubercle growth could restrict cooling water flow to equipment.
diesel generators are stagnant because motor-operated isolation valves are


Stainless
normally maintained shut (except during monthly surveillance testing).


steel piping is not immune to microbiologically
Crevices such as those in piping welds that lack penetration can enhance


influenced
microbiologically influenced corrosion attack by giving a place for deposits


corrosion because microbes can attack at the weld heat affected zone (HAZ) in stainless steels when this zone becomes sensitized.
and, therefore, for the bacteria to collect. Microbial films form when


Microbiologically
aerobic species, such as iron-oxidizing bacteria, create anaerobic conditions


influenced
underneath them for microorganisms, such as sulfate-reducing bacteria, to


corrosion
accumulate at the metal surface.    Sulfate-reducing bacteria attack the metal


can also damage metals lined with polymeric
surface, produce  corrosive chemicals, and cause deep pitting.


materials, typically
K>J                                    IN 94-79 November 23, 1994 Microbiologically influenced corrosion on carbon steel will increase general


at coating imperfections.
corrosion, through-wall pitting, and the formation of tubercles. Tubercles


Once microbial
consist of corrosion products, microbes, and debris. Tubercle growth could


films are established
restrict cooling water flow to equipment.


on metal surfaces, they are extremely difficult
Stainless steel piping is not immune to microbiologically influenced corrosion


to eliminate
because microbes can attack at the weld heat affected zone (HAZ) in stainless


because of the resiliency
steels when this zone becomes sensitized. Microbiologically influenced


of the individual
corrosion can also damage metals lined with polymeric materials, typically at


microorganisms.
coating imperfections.


Biocides are applied by some licensees
Once microbial films are established on metal surfaces, they are extremely


in areas where continuous
difficult to eliminate because of the resiliency of the individual


flow conditions
microorganisms. Biocides are applied by some licensees in areas where


cannot be maintained.
continuous flow conditions cannot be maintained. However, biocide treatments


===However, biocide treatments===
are not always effective against established microorganism colonies because
are not always effective


against established
the biocide cannot penetrate through the tubercles or aerobic biofilms.


microorganism
Treatment against established colonies involves a combination of mechanical or


colonies because the biocide cannot penetrate
chemical pipe cleaning, continued water treatment and regular maintenance.


through the tubercles
Continuous flow conditions have been found to prevent the attachment and


or aerobic biofilms.Treatment
growth of microbial films.


against established
It may be necessary to replace materials if microbiologically influenced


colonies involves a combination
corrosion severely damages them or where mitigation measures cannot bring the


of mechanical
system condition under control. Possible alternatives include replacing


or chemical pipe cleaning, continued
carbon steel with stainless steel or replacing stainless steel with more


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


and regular maintenance.
base alloys, titanium, or nonmetallic materials.


Continuous
The licensee did not regularly treat the Beaver Valley River water supply


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


have been found to prevent the attachment
injection point for the main river water headers is downstream of the branch


and growth of microbial
lines to the emergency diesel generators. It also appears that the existing


films.It may be necessary
program at Haddam Neck of hypochlorite injection was not successful in


to replace materials
mitigating the microbiologically influenced corrosion problems in stagnant


if microbiologically
dead-end lines at such locations as the emergency diesel generator supply.


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


corrosion
you have any questions about the information in this notice, please contact


severely damages them or where mitigation
one of the technical contacts listed below or the appropriate Office of


measures cannot bring the system condition
Nuclear Reactor Regulation (NRR) project manager.


under control. Possible alternatives
Vv BaD


include replacing carbon steel with stainless
D ision f Project Support


steel or replacing
Office of Nuclear Reactor Regulation


stainless
Technical contacts:  Michael Modes, RI    James A. Davis, NRR


steel with more resistant
(215) 337-5198      (301) 504-2713 Peter P. Sena, RI    Vern Hodge, NRR


materials, such as 6-percent
(412) 643-2000      (301) 504-1861 Attachment:


molybdenum
===List of Recently===
hi                  It6        J'4 ssued NRC Information Notices


stainless
K>
                                                          Attachment


steels, nickel base alloys, titanium, or nonmetallic
IN 94-79 November 23, 1994 LIST OF RECENTLY ISSUED


materials.
NRC INFORMATION NOTICES


The licensee did not regularly
===Information                                  Date of===
Notice No.            Subject                Issuance    Issued to


treat the Beaver Valley River water supply lines to the diesel with biocide or corrosion
94-78          Electrical Component          11/21/94    All holders of OLs or CPs


inhibitors.
Failure due to Degrada-                    for nuclear power reactors.


===The chlorination===
tion of Polyvinyl Chloride
injection


point for the main river water headers is downstream
Wire Insulation


of the branch lines to the emergency
94-77          Malfunction in Main Gen-      11/17/94    All holders of OLs or CPs


diesel generators.
erator Voltage Regulator                  for nuclear power reactors.


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


injection
Safety-Related Electrical


was not successful
Equipment


in mitigating
94-76          Recent Failures of Charging/  10/26/94    All holders of OLs or CPs


the microbiologically
Safety Injection Pump Shafts              for pressurized water


influenced
reactors.


corrosion
93-60,        Reporting Fuel Cycle          10/20/94    All 10 CFR Part 70
Supp. 1        and Materials Events to                    fuel cycle licensees.


problems in stagnant dead-end lines at such locations
the NRC Operations Center


as the emergency
94-75          Minimum Temperature          10/14/94    All holders of OLs or CPs


diesel generator
for Criticality                            pressurized-water reactors


supply.
(PWRs).


IN 94-79 November 23, 1994 This information
94-74          Facility Management          10/13/94    All U.S. Nuclear Regulatory


notice requires no specific action or written response.
Responsibilities for                      Commission Medical


If you have any questions
Purchased or Contracted                    Licensees.


about the information
Services for Radiation


in this notice, please contact one of the technical
Therapy Programs


contacts listed below or the appropriate
94-73          Clarification of Critical-    10/12/94    All fuel fabrication


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


Technical
94-72          Increased Control Rod        10/05/94    All holders of OLs or CPs


contacts:
Drop Time from Crud                        for pressurized water
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
Buildup                                    reactors.


IN 94-79 November 23, 1994 LIST OF RECENTLY ISSUED NRC INFORMATION
94-71          Degradation of Scram          10/04/94    All holders of OLs or CPs


NOTICES Information
Solenoid Pilot Valve                      for boiling water reactors


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
Pressure and Exhaust                      (BWRs).


Component Failure due to Degrada-tion of Polyvinyl
Diaphragms


===Chloride Wire Insulation===
OL - Operating License
Malfunction


in Main Gen-erator Voltage Regulator Causing Overvoltage
CP = Construction Permit


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


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


Equipment Recent Failures of Charging/Safety Injection
injection point for the main river water headers is downstream of the branch


Pump Shafts Reporting
lines to the emergency diesel generators. It also appears that the existing


Fuel Cycle and Materials
program at Haddam Neck of hypochlorite injection was not successful in


Events to the NRC Operations
mitigating the microbiologically influenced corrosion problems in stagnant


===Center Minimum Temperature===
dead-end lines at such locations as the emergency diesel generator supply.
for Criticality


===Facility Management===
This information notice requires no specific action or written response. If
Responsibilities


for Purchased
you have any questions about the information in this notice, please contact


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


Services for Radiation Therapy Programs Clarification
Nuclear Reactor Regulation (NRR) project manager.


of Critical-ity Reporting
Original signed by B.D. Liaw for


Criteria Increased
Brian K. Grimes, Director


Control Rod Drop Time from Crud Buildup Degradation
Division of Project Support


of Scram Solenoid Pilot Valve Pressure and Exhaust Diaphragms
Office of Nuclear Reactor Regulation


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
Technical contacts:                Michael Modes, RI            James A. Davis, NRR


water reactors.All 10 CFR Part 70 fuel cycle licensees.
(215) 337-5198                (301) 504-2713 Peter P. Sena, RI              Vern Hodge, NRR


All holders of OLs or CPs pressurized-water
(412) 643-2000                (301) 504-1861 Attachment:          List of Recently Issued NRC Information Notices


reactors (PWRs).All U.S. Nuclear Regulatory
*err DDrFlVT)         rnCUriRFNrEN


Commission
OFFICE                    *OGCB/DORS              *TECH ED            *REGION I          *REGION I


Medical Licensees.
NAME


===All fuel fabrication===
DATE
facilities.


All holders of OLs or CPs for pressurized
__ _
    *Ann-nfEDrIOTAN


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


License CP = Construction
__  _
                            J_
                            -EI


Permit
CVHodge


-1/4<> A~-' IN 94-79 November 23, 1994 The licensee did not regularly
09/08/94
                                _
                                T


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


inhibitors.
* FMrR/nF


===The chlorination===
JDMain
injection


point for the main river water headers is downstream
09/09/94 vv.1,EI__
                                                                *S:EMCB/DE


of the branch lines to the emergency
- -
                                                                            MCModes


diesel generators.
09/01/94 I


It also appears that the existing program at Haddam Neck of hypochlorite
*C: EMCB/DE


injection
PPSena


was not successful
__
                                                                                                10/03/94 If_
    ARBlough                              JADavis            RAHermann          JRStrosnider


in mitigating
10/03/94                              09/20/94            09/20/94
                                          -~~~        II                              f


the microbiologically
*n. _. nr


influenced
v.LvL                  *nCrRR /nnP5  -
                                                        I *C AFCBIDOPS        I D:DdPWi/Or


corrosion
BWSheron                  RLDennig                  AEChaffee                G&      I_J1
      10/06/94                  10/20/94                  10/25/94            1 1ff_/_ 4 Lj


problems in stagnant dead-end lines at such locations
DOCUMENT NAME:            94-79.IN


as the emergency
IN 94-XX


diesel generator
October xx, 1994 inhibitors.    The chlorination injection point for the main river


supply.This information
water headers is downstream of the branch lines to the emergency


notice requires no specific action or written response.
diesel generators.     It also appears that the existing program at


If you have any questions
in


about the information
Haddam Neck of hypochlorite injection was not successful


in this notice, please contact one of the technical
influenced          corrosion      problems  in


contacts listed below or the appropriate
mitigating the microbiologically


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
locations      as      the  emergency    diesel


Technical
stagnant dead-end lines to such


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:
generator supply.
List of Recently Issued NRC Information


Notices*err DDrFlVT) rnCUriRFNrEN
This information notice requires no specific action or written


OFFICE *OGCB/DORS
response.    If you have any questions about the information in


*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
this notice, please contact one of the technical contacts listed


T I
below or the appropriate Office of Nuclear Reactor Regulation


* FMrR/nF*S:EMCB/DE
(NRR) project manager.


*C: EMCB/DE , I vv.1,EI *vI __ , --ARBlough JADavis RAHermann
Brian K. Grimes, Director


===JRStrosnider===
Division of Operating Reactor
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
Support


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


IN 94-XX October xx, 1994 inhibitors.
Regulation


The chlorination
Technical contacts:    Michael Modes, Region I


injection
(215) 337-5198 Peter P. Sena, Region I


point for the main river water headers is downstream
(412) 643-2000
                        James A.Davis, NRR


of the branch lines to the emergency diesel generators.
(301) 504-2713 Attachment:    List of Recently Issued NRC Information Notices


It also appears that the existing program at Haddam Neck of hypochlorite
*SEE PREVIOUS CONCURRENCE


injection
OFFICE        *OGCB/DORS      *TECH ED            *REGION I              *REGION I


was not successful
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in mitigating
DATE          09/08/94      j09/09/94              09/01/94              10/03/94
                                      .          _                -11
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the microbiologically
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influenced
10/03/94              09/20/94        09/20/94              09      94
                              -    -                I - I ~'            - 7i


corrosion
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problems in stagnant dead-end lines to such locations
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as the emergency
10/06/94        1,/94
                10/9              10/      /94      ________
_
DOCUMENT NAME:    NECK-MIC.INY


diesel generator
-
                                                                  IN 94-XX


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


notice requires no specific action or written response.
generator supply.


If you have any questions
This information notice requires no specific action or written


about the information
response.              If you have any questions about the information in


in this notice, please contact one of the technical
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


contacts:
Division of Operating Reactor
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
Support


OFFICE *OGCB/DORS
Office of Nuclear Reactor


*TECH ED *REGION I *REGION I NAME CVHodge JDMain MCModes PPSena DATE 09/08/94 j09/09/94
Regulation
09/01/94 10/03/94._ -11*Ann:DRA/RFCION


I I *EMCB/DE I *S:EMCB/DE
Technical contacts:                  Michael Modes, Region I


I *C:EMCB/DE
(215) 337-5198 Peter P. Sena, Region I


ARBlough JADavis RAHermann
(412) 643-2000
                                      James A. Davis, NRR


===JRStrosnider===
(301) 504-2713 Attachment:               List of Recently Issued NRC Information Notices
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.
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NAME


xx, 1994 stagnant dead-end lines to such locations
DATE


as the emergency
*OGCB/DORS


diesel generator
CVHodge


supply.This information
j09/08/94 I *TECH ED


notice requires no specific action or written response.
JDMain


If you have any questions
09/09/94
                                                                    *REGION I


about the information
MCModes


in this notice, please contact one of the technical
09/01/94 REGION I


contacts listed below or the appropriate
PPSena


Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
ff /o3/94 A


===Reactor Support Office of Nuclear Reactor Regulation===
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contacts: Michael Modes, Region I (215) 337-5198 Peter P. Sena, Region I (412) 643-2000 James A. Davis, NRR (301) 504-2713 Attachment:
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List of Recently Issued NRC Information


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                                                      1~.1 Dkbz                    AC:OGCB/DORS           D:DORS/NRR


*TECH ED *REGION I REGION I A NAME CVHodge I JDMain MCModes PPSena DATE j09/08/94
BW          on        ELDoolittle            BKGrimes
09/09/94 09/01/94 ff /o3/94_ I ., ._II annlnPq/RFnTON


T*EMCB/DE*S: EMCB/DE C;EMCB/DE
__/__      /94          09/    /94            09/     /94 DOCUMgNT NAME:                NECK-MIC.1fir


fir-_ I___ __a _ v_ --ARBlough JADavis RAHermann
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===LdRStrosnider===
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D:DORS/NRR
IN 94-XX


BW on ELDoolittle
September xx, 1994 This information notice requires no specific action or written


BKGrimes__/__ /94 09/ /94 09/ /94 DOCUMgNT NAME: NECK-MIC.1fir
response.   If you have any questions about the information in


A-- 016 I IN 94-XX September
this notice, please contact one of the technical contacts listed


xx, 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


about the information
Division of Operating Reactor


in this notice, please contact one of the technical
Support


contacts listed below or the appropriate
Office of Nuclear Reactor


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


===Reactor Support Office of Nuclear Reactor Regulation===
Technical contacts:      Michael Modes, Region I
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:
(215) 337-5198 Peter P. Sena, Region I
List of Recently Issued NRC Information


Notices*SEE PREVIOUS CONCURRENCE
(412) 643-2000
                          James A. Davis, NRR


--- eIml e .Ac>Iveiw
(301) 504-2713 Attachment:    List of Recently Issued NRC Information Notices


6 2 OFFICE OGCB/DORS
*SEE PREVIOUS CONCURRENCE            ---      e


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
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I EMCB/DE S:EMCB/DF C:EMCB/DE ARBlough JADa RAHermann
NAME          CVHodge  k  ^JDMain            MCModes          PPSena


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


D:DORS/NRR
ARBlough            JADa          RAHermann      JRStrosnider


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


BKGrimes 09/ /94 09/ /94 09/ /94 DOCU;MENT
BWSheron      ELDoolittle    BKGrimes


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


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

Revision as of 03:29, 24 November 2019

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

power

All holders of operating licenses or construction permits for nuclear

reactors.

PurDose

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

notice to alert addressees to degradation resulting from microbiologically

service water

influenced corrosion in carbon steel piping systems that supply will review

to emergency diesel generators. It is expected that recipients actions, as

the information for applicability to their facilities and consider in

appropriate, to avoid similar problems. However, suggestions contained

specific

this information notice are not NRC requirements; therefore, no

action or written response is required.

Description of Circumstances

Haddam Neck Plant

water

On February 12, 1994, a through-wall leak developed in the serviceleak occurred

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

light surface

in a weld in an area of low flow, where the licensee was doing in March

grinding to prepare for ultrasonic test (UT) inspection. Previously, with the "B" emergency

1993, the licensee had found a similar leak associated the pipe, diesel generator. After removing the leaking section and examining weld quality

the licensee determined that the leak was caused by poor initial

of some welds

and microbiologically influenced corrosion. Lack of penetration emergency

created a crevice condition. Radiographic tests (RT) of additional

welds

diesel generator service water system piping revealed three additionalof these

that could form similar leaks. It was during preparation of one

the "A"

welds for UT examination that the through-wall leak associated with

emergency diesel generator was found.

in

The licensee had previously performed a structural integrity determination

of a sharp

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

,disruption, the licensee had at that time concluded that the worst-case unisolable

degraded cross-section of the as-found pipe welds, located in the Generic

portions of the emergency diesel generator supply piping, met the

that the

Letter 90-05 acceptance criteria for structural integrity and integrity to

degraded piping would have sufficient mechanical and structural

remain operable. &_ r" .

in '^*

94170C )K I TE NO-rice H#-14-u1 T4 lII /-

9411170039 towzl +2ji

-"5

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

hi It6 J'4 ssued NRC Information Notices

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 Electrical Component 11/21/94 All holders of OLs or CPs

Failure due to Degrada- for nuclear power reactors.

tion of Polyvinyl Chloride

Wire Insulation

94-77 Malfunction in Main Gen- 11/17/94 All holders of OLs or CPs

erator Voltage Regulator for nuclear power reactors.

Causing Overvoltage at

Safety-Related Electrical

Equipment

94-76 Recent Failures of Charging/ 10/26/94 All holders of OLs or CPs

Safety Injection Pump Shafts for pressurized water

reactors.

93-60, Reporting Fuel Cycle 10/20/94 All 10 CFR Part 70

Supp. 1 and Materials Events to fuel cycle licensees.

the NRC Operations Center

94-75 Minimum Temperature 10/14/94 All holders of OLs or CPs

for Criticality pressurized-water reactors

(PWRs).

94-74 Facility Management 10/13/94 All U.S. Nuclear Regulatory

Responsibilities for Commission Medical

Purchased or Contracted Licensees.

Services for Radiation

Therapy Programs

94-73 Clarification of Critical- 10/12/94 All fuel fabrication

ity Reporting Criteria facilities.

94-72 Increased Control Rod 10/05/94 All holders of OLs or CPs

Drop Time from Crud for pressurized water

Buildup reactors.

94-71 Degradation of Scram 10/04/94 All holders of OLs or CPs

Solenoid Pilot Valve for boiling water reactors

Pressure and Exhaust (BWRs).

Diaphragms

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, 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 Issued NRC Information Notices

  • err DDrFlVT) rnCUriRFNrEN

OFFICE *OGCB/DORS *TECH ED *REGION I *REGION I

NAME

DATE

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09/08/94

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10/03/94 09/20/94 09/20/94

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10/06/94 10/20/94 10/25/94 1 1ff_/_ 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

in

Haddam Neck of hypochlorite injection was not successful

influenced corrosion problems in

mitigating the microbiologically

locations as the emergency diesel

stagnant dead-end lines to such

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 ~' - 7i

  • n FOEC 6I1QS I C:994A2'OPS I IWS/NRR

BWSheron RLW A af e jB jes

10/06/94 1,/94

10/9 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

  • QVV DPRVUSTnT1 CONCURRENCE .-- "tfA R'lena-

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L: V - __s_ ___ -r- - m --

OFFICE

NAME

DATE

  • OGCB/DORS

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j09/08/94 I *TECH ED

JDMain

09/09/94

  • REGION I

MCModes

09/01/94 REGION I

PPSena

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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 --- e

eIml .Ac>Iveiw62 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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