United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 84-63: Defective RHR Replacement Piping

                                                            SSINS No.: 6835 
                                                            IN 84-63       

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C. 20555

                               August 13, 1984

Information Notice No. 84-63:   DEFECTIVE RHR REPLACEMENT PIPING 

Addressees: 

All nuclear Power reactor facilities holding an operating license (OL) or 
construction permit (CP). 

Purpose: 

This information notice is being provided to inform licensees of a 
potentially significant problem pertaining to defects in large diameter 
piping formed by hot piercing and inspected to the Summer of 1980 Addenda to
the ASME Boiler and Pressure Vessel Code1. The NRC is continuing to evaluate
this issue; meanwhile, recipients are expected to review this notice for 
applicability to their facilities. Suggestions contained in this notice do 
not constitute NRC requirements; therefore, no specific action or written 
response is required. 

Description of Circumstances: 

On June 29, 1984, Northern States Power Company reported, in a 10 CFR 21 
report, that base metal discontinuities had been discovered in the 18-inch 
ASME Class 1 pipe furnished to Specification SA-333, Grade 6, and special 
requirements of SA-655 for replacement piping for the residual heat removal 
(RHR) system for its Monticello nuclear plant. While spool pieces were being
fabricated at the site, the defect was seen in the section of pipe that was 
to be used to connect the RHR lines to the recirculation system on the 
discharge side of the RHR pump inside primary containment. The design 
pressure of the spool piece was 1248 psig at 562F. Further visual and 
ultrasonic testing (UT) determined that the defect extended significantly 
into the pipe wall. 

The defect was found to be a laminar type discontinuity that had opened and 
separated in several areas. It was located about half way along the length 
of the pipe, running about 360 around the inside and extending 0.44 
inches into the material (43% through the wall). The orientation of the 
discontinuity was oblique to the surfaces. 



8408100009 



1  ASME Boiler and Pressure Vessel Code, Section II, Part A, 1980 Edition. 
Summer of 1980 Addenda, American Society of Mechanical Engineers, New York, 
NY 
.

                                                           IN 84-63       
                                                           August 13, 1984 
                                                           Page 2 of 3    

A second defect was found in another piece of SA-333, Grade 6 piping. It was
determined to extend 330 around the interior of the pipe and 0.2 inches
deep (19% through the wall). 

Northern States Power plans to perform a comprehensive UT scan on all 
replacement pipe used in the RHR system, using a five scan inspection: two 
directions axially, two circumferentially, and a straight beam. The supplier
of the piping had conducted inspections in compliance with the Code 
Specification SA-655. These were inadequate to detect the defects that were 
found. SA-655 calls for scans in both circumferential directions only. 
Without axial scans or straight beam, defects such as these can go 
undetected. 

In hot forming of seamless piping, a momentary loss of tool lubricant, hot 
scale release, or tool wear can result in embedded folds, laps, and seams in
the piping. Because of expansion dynamics associated with hot forming, the 
piping may also be severely stressed locally to a degree that material 
inhomogeneities become prone to laminar separation or cracking. The 
frequency and orientation of these processing discontinuities are not 
predictable and their presence may not be detected solely on the basis of 
visual inspection. It is necessary, therefore, that greater emphasis be 
placed on a comprehensive ultrasonic examination, as described above, to 
assure that unacceptable manufacturing defects, irrespective of orientation, 
are detected and eliminated in piping used in the reactor coolant pressure 
boundary and other safety-related systems during the current and future 
replacement programs. 

Regulatory Guide 1.68, "Nondestructive Examination of Tubular Products", was
issued in October of 1973, calling for the examination of pipe and tubing to
the ASME Code requirements in NB2550 supplemented by ASTM E-2132, "Standard 
Method for Ultrasonic Inspection of Metal Pipe and Tubing for Longitudinal 
Discontinuities." Supplementing these requirements, the Regulatory Guide 
specified that ultrasonic examination be performed in both axial and both 
circumferential directions. The Reg Guide was withdrawn in October of 1977 
as announced in Federal Register notice 42 FR 54478 on the premise that the 
ASME Code Section III, at that time had adopted the supplementary 
requirements of the Regulatory Guide. Comprehensive review of the 
appropriate Codes and their referenced standards since that time failed to 
locate any unambiguous standard which included the supplementary 
requirements of the Regulatory Guide in Code Sections II or III or in 
referenced material standards; i.e. , E-213, A-655, SA-655, etc. Further NRC 
action in this matter is being contemplated. 

2  American Society for Testing and Materials, 1916 Race Street, 
Philadelphia, Pennsylvania 19103 
.

                                                           IN 84-63       
                                                           August 13, 1984 
                                                           Page 3 of 3    

No written response to this information notice is required. If there are any
questions regarding this matter, please contact the Regional Administrator 
of the appropriate NRC regional office or this office. 



                                   Edward L. Jordan Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 

Technical Contact:  Mary S. Wegner, IE 
                    (301) 492-4511 

                    W. J. Collins, IE
                    (301) 492-9630

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