United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 88-82: Torus Shells with Corrosion and Degraded Coatings in BWR Containments

                                  UNITED STATES
                          NUCLEAR REGULATORY COMMISSION
                      OFFICE OF NUCLEAR REACTOR REGULATION
                             WASHINGTON, D.C.  20555

                                October 14, 1988


Information Notice No. 88-82:  TORUS SHELLS WITH CORROSION AND 
                                   DEGRADED COATINGS IN BWR CONTAINMENTS


Addressees:

All holders of operating licenses or construction permits for boiling water 
reactors (BWRs).

Purpose:

This information notice is being provided to alert addressees to the discovery
of suppression pool steel shells with corrosion and degraded coatings in BWR 
containments.  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 do not constitute NRC requirements; therefore, no specific action or 
written response is required.

Description of Circumstances:

During recent NRC inservice inspections (50-220/88-09 and 50-410/88-09) at the
Nine Mile Point Nuclear Station (NMPNS), inspectors found that the inside 
surface of the torus shell at Unit 1, which was designed and constructed as 
uncoated, had corroded.  Furthermore, the NRC inspectors' independent 
thickness measurements of the torus shell revealed several areas in which the 
thickness was at or below the minimum specified wall thickness.  Based on 
additional analysis, it was determined that the shell thickness is acceptable 
until June 1989 at which time the licensee will perform an ultrasonic 
reexamination of the torus shell.  Based on the findings, the licensee is 
committed to take corrective actions. 

A recent survey of BWRs located in NRC Region I also revealed that some Mark I
tori had experienced degradation of the coating and that cleaning and 
recoating were required.  The cause of these degradations is not yet fully 
understood.

Discussion:

Although the torus shell thinning due to corrosion observed at NMPNS Unit 1 
and the coating degradation in tori of other Region I plants have no immediate
effect on plant operation, the NRC staff considers these deficiencies to be 
significant because the measured corrosion rates of torus shells are greater 
than the corrosion rates assumed as part of the original design.  The torus 
shell degradation, if it continues, may jeopardize containment integrity.

8810070114
.                                                       IN 88-82
                                                       October 14, 1988
                                                       Page 2 of 2


Many licensees of BWR plants are currently required to perform periodic visual
inspections of the suppression pool steel shells or liners in accordance with 
their technical specifications, but the methods used by licensees vary.  Some 
licensees examine only those portions of the torus above the water line, and 
others employ divers or use cameras to inspect submerged surfaces.  Such 
inspections can only detect general degradation.  Localized degradation such 
as pitting can be detected most effectively by draining the torus and 
inspecting it under dry conditions.  In view of the importance of the 
containment to the health and safety of the general public, licensees may wish
to review and evaluate the adequacy of their containment surveillance programs
to determine if any problems similar to those described above exist at their 
plants.

This information notice also applies to suppression pools for other types of 
BWR containments (Mark II and Mark III), whether built of steel or of concrete
with a steel liner, because the steel shell or liner may degrade through 
disintegration of the paint system and /or corrosion of the base metal.

No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical 
contact listed below or the Regional Administrator of the appropriate regional
office.




                              Charles E. Rossi, Director
                              Division of Operational Events Assessment
                              Office of Nuclear Reactor Regulation


Technical Contact:  Chen P. Tan, NRR
                    (301) 492-0829


Attachment:  List of Recently Issued NRC Information Notices
.                                                            Attachment 
                                                            IN 88-82 
                                                            October 14, 1988 
                                                            Page 1 of 1

                             LIST OF RECENTLY ISSUED
                            NRC INFORMATION NOTICES 
_____________________________________________________________________________
Information                                  Date of 
Notice No._____Subject_______________________Issuance_______Issued to________

88-81          Failure of Amp Window         10/7/88        All holders of OLs
               Indent Kynar Splices                         or CPs for nuclear
               and Thomas and Betts                         power, test, and 
               Nylon Wire Caps During                       research reactors.
               Environmental Quali-
               fication Testing 

88-80          Unexpected Piping Movement    10/7/88        All holders of OLs
               Attributed to Thermal                        or CPs for PWRs. 
               Stratification 

88-79          Misuse of Flashing Lights     l0/7/88        All holders of OLs
               for High Radiation Area                      or CPs for nuclear
               Controls                                     power reactors. 

88-69, Supp 1  Movable Contact Finger        9/29/88        All holders of OLs
               Binding in HFA Relays                        or CPs for nuclear
               Manufactured by General                      power reactors. 
               Electric (GE) 

88-78          Implementation of Revised     9/22/88        All holders of OLs
               NRC-Administered Requali-                    or CPs for nuclear
               fication Examinations                        power reactors. 

88-77          Inadvertent Reactor           9/22/88        All holders of OLs
               Vessel Overfill                              or CPs for BWRs. 

88-76          Recent Discovery of a         9/19/88        All holders of OLs
               Phenomenon not Previously                    or CPs for nuclear
               Considered in the Design                     power reactors. 
               of Secondary Containment 
               Pressure Control 

88-75          Disabling of Diesel           9/16/88        All holders of OLs
               Generator Output Circuit                     or CPs for nuclear
               Breakers by Anti-Pump                        power reactors. 
               Circuitry 

88-74          Potentially Inadequate        9/14/88        All holders of OLs
               Performance of ECCS in                       or CPs for W and 
               PWRs During Recirculation                    B&W-designed 
               Operation Following a LOCA                   nuclear power 
                                                            reactors. 
_____________________________________________________________________________
OL = Operating License
CP = Construction Permit 

Page Last Reviewed/Updated Tuesday, November 12, 2013