IE Circular No. 79-11 - Design/Construction Interface Problem


                               June 21, 1979 

MEMORANDUM FOR:     B. H. Grier, Director, Region I 
                    J. P. O'Reilly, Director, Region II 
                    J. G. Keppler, Director, Region III 
                    K. V. Seyfrit, Director, Region IV 
                    R. H. Engelken, Director, Region V 

FROM:               Harold D. Thornburg, Director, Division of Reactor 
                      Construction Inspection, IE 


     The subject circular should be dispatched for action to all applicants 
for, and holders of power reactor construction permits no later than June 
27, 1979.  The text of the circular and draft letter to licensees are 
enclosed for this purpose. 

                                   Harold D. Thornburg, Director 
                                   Division of Reactor Construction 
                                   Office of Inspection and Enforcement 

1.   Draft Transmittal Letter
2.   IE Circular No. 79-11

CONTACT:  W. Laudan, IE 

(Draft letter to all applicants for, and holders of construction permits) 

                                                      IE Circular No. 79-11 


The enclosed Circular 79-11, is forwarded to you for information. No written
response to this Circular is required. If you require additional information
regarding this subject, please contact this office. 


                                        (Regional Director) 

1.   IE Circular No. 79-11 
2.   List of IE Circulars 
       Issued in the Last 
       12 Months 

                             UNITED STATES 
                          WASHINGTON, D.C. 20555 
                              June 27, 1979  

                                                   IE Circular No. 79-11 


Description of Circumstances: 

Apparent inadequate communication between nuclear steam supply system 
(NSSS), architect/engineer (A/E) and constructors have resulted in several 
cases where reactor vessels or the supports have been misoriented. The 
misorientation problems appear to occur at sites where dual reactor units 
are being constructed and one primary system layout is a mirror image of the

In 1975 TVA reported a misorientation problem with the Sequoyah Unit 2 
reactor vessel. Westinghouse was the NSSS supplier and TVA provided their 
own A/E service. 

In 1977 the Southern California Edison Company reported a reactor vessel 
misorientation at San Onofre Unit 2. Combustion Engineering was the NSSS 
supplier and Bechtel provided the A/E service. 

In 1979 the Texas Utilities Generating Company reported a reactor vessel 
support system misorientation at Comanche Peak Unit 2. Westinghouse supplied
the NSSS, Gibbs and Hill was the plant engineer and Brown and Root was the 

Even though there appears to be minimal safety implications associated with 
the particular misorientation problems mentioned, repetition of the same 
type of errors suggests breakdowns in the design/construction interface 
relationships that could in turn lead to more significant safety problems. 

Corrective preventive action is recommended for the following reasons: 

.    If the interface control system between the NSSS/AE/Construction is 
     marginal or ineffective as evidenced by the misorientation of reactor 
     vessels and their supports, it is possible that other safety related 
     equipment may also be misoriented and/or mislocated. In some cases the 
     errors may not be as obvious as a misoriented reactor vessel. 

.    This type of error can and has resulted in hardware modifications and 
     could cause functional and/or structural changes that affect design and
     operating parameters. 

.    In translating NSSS design information into site construction 
     documents, the A/E may make changes to facilitate construction of the 
     balance of plant. These translations may also introduce errors which 
     may not be 

IE Circular No. 79 - 11                                    June 27, 1979 
                                                            Page 2 of 2 

     recognized as errors by the A/E's review system. The organization 
     responsible for function and/or structural design must be made aware of
     changes affecting design and operating 'parameters so that proper 
     evaluation is performed. 

It is recognized that there are effective field construction inspection 
systems, deficiency reporting systems and as-built check systems to uncover 
and correct for deviations from design. However, these are reactive type 
systems that address the problems after the errors occur and that rely on 
detection of errors and design deviations in the construction phase. The 
detection of certain other errors and design deviations may only be 
recognizable at the design level. 

The NRC's concern is that in some instances sufficient checks at the design 
level are not being performed to preclude design errors discovered at the 
construction site and that the designer may not be aware of other design 
related changes that affect design and operating parameters. The 10 CFR 50, 
Appendix B requirement that addresses this concern is contained in Criteria 
III which states in part: 

     "Measures shall be established for the identification and control of 
     design interfaces and for coordination among participating design 
     organizations. These measures shall include the establishment of 
     procedures among participating design organizations for the review, 
     approval, release, distribution, and revision of documents involving 
     design interfaces." 

Preventive action at the design level is necessary to minimize the 
possibility of the appropriate parties not being aware of A/E and 
construction related design changes and to prevent errors from occurring. An
appropriate preventive action would be to have the NSSS review A/E drawings 
that show the location, orientation, clearance, etc., for equipment that the
NSSS has functional and/or structural design responsibility. 

All holders of construction permits should be aware of the potential 
problems caused by inadequate communication between the design organization 
and the construction organization and should take appropriate action to 
assure themselves that adequate interface controls are established and 

No written response to this circular is required. If you require additional 
information regarding this matter, contact the Director of the appropriate 
NRC Regional Office. 


Page Last Reviewed/Updated Thursday, March 25, 2021