Part 21 Report - 1996-712

 
 
ACCESSION #: 9611200157

NAK Engineering, Inc.
420 AVIATION BLVD., SANTA ROSA, CA 95403
TELEPHONE: (707) 542-9996  FAX: (707) 542-6666

Oct 10, 1996

Document Control Desk
U.S.  Nuclear Regulatory Commission
Washington, DC 20555

Dear Sir,

Pursuant to my letter dated Aug.  5, 1996 and in accordance with the
requirements of Title 10, Chapter 1, Code of Federal Regulations, Part
21.  NAK Engineering, Inc.  has established and adopted revised
procedures to assemble fuel oil lines and climate the possible detective
condition that was found at Mcguire.  We have notified each of the
affected nuclear stations and furnished copies of the new assembly
procedures to the system engineers at McGuire and Brunswick.  Through
direct communications with the responsible system engineers, we have been
advised that the both cites are fully aware of the possible defect or
condition and have taken necessary action to examine the affected parts
and perform any necessary repairs.

As stated in my letter of Aug.  5, 1996, the root cause of the failure
was determined to be an inadequate tightening value to insure the correct
seating of the sleeve that seal the fuel line connection.  The revised
procedure incorporates specific tightening values, inspection criteria,
and acceptance values to determine if the "crimping" of the sleeve is
adequate.

Should anyone have any questions regarding, this condition or corrective
action please contact:

                              Norman,E.  Nelson
                             NAK Engineering, Inc.
                              420 Aviation Blvd.
                             Santa Rosa, Ca. 95403

                              phone: 707-542-9996
                               fax: 707-542-6666

Sincerely,

Norman E.  Nelson
Manager, Quality Assurance

               NAK Engineering, Inc.

          420 AVIATION BLVD., SANTA ROSA, CA 95403
     TELEPHONE: (707) 542-9996     FAX: (707) 542-6666

August 5, 1996

Document Control Desk
U. S.  Nuclear Regulatory Commission
Washington, DC 20555

Dear Sir,

in accordance with the requirements of Title 10, Chapter 1, Code of
Federal Regulations, Part 21, NAK Engineering, Inc.  hereby notifies the
Commission of a potential defect or condition in a component of the
Nordberg model FS1316HSC Standby Diesel Generator.  There exists a
potential problem with the fuel injection line assembly which connects
the fuel pump to the injector.

NAK Engineering, Inc.  has supplied these fuel line assemblies to the
following sites:

UTILITY                  SITE           SERIAL NUMBER(S)    MODEL

Duke Power Co            McGuire        1030-1270/1273      FS 1316 HSC

Carolina Power & Light   Brunswick      1030-1328/1331      FS 1316 HSC

On or about June 20, 1996, we were advised of a single leaking fuel line
assembly that occurred on McGuire Nuclear Station's Emergency Diesel
Generator Unit 1B, Cylinder 4R. It was determined that the leak was
caused by the fuel line sleeve coming loose which eliminated the fuel
connection seal.

There were no unusual engine noises, temperature changes, cylinder firing
pressure changes noted prior to the fuel line leak.  The operator
discovered significant fuel spray emitting from the fuel pump.

At this time Duke Power initiated a ROOT CAUSE FAILURE ANALYSIS
investigation and they determined that the probable cause was inadequate
crimping of the ferrule sleeve onto the fuel line during assembly.  In
order to establish corrective action, tests were conducted by Duke Power
Co.  at their McGuire Nuclear Station's Met Lab to evaluate different
torque and tightening values to determine the values to achieve optimum
"crimping" of the ferrule sleeve.  Samples of the same fuel line
material, and ferrule sleeves, were provided, Duke installed the ferrule
sleeves at varying torque values and conducted "pull" tests.  It was
concluded that the fuel line nut should be tightened 1 1/8-1 1/4 turns
past hand tight or 150 ft lbs. of torque to achieve optimum ferrule

sleeve crimping.

While corrective action procedures have been implemented, the fuel line
replacement on cylinder number 4R was installed before the corrective
action procedures were finalized and before corrective action was taken.
It was further believed that this was a unique occurrence On July 30,
1996 the replacement fuel line developed the same leaking problem.  Since
then all fuel lines produced and furnished after July 18, 1996 have been
assembled using the new torque and tightening techniques.

All fuel line assemblies supplied before July 18, 1996, either in
service, or in site inventories, should either be retained to NAK
Engineering, Inc.  for examination and the crimping tightening procedures
checked and verified or this work should be done on site, A written
procedure will be furnished within the next 60 days to the affected sites
to accomplish the necessary inspection and repairs.

Should anyone have any questions regarding this condition or corrective
action please contact:

                                        Norman E.  Nelson
                                        NAK Engineering, Inc.
                                        420 Aviation Blvd.
                                        Santa Rosa, Ca. 95403

                                        phone: 707-542-9996
                                        fax: 707-542-6666

A copy of this letter will be forwarded to all of the affected sites
referenced in paragraph 2 of this letter.

Sincerely,

Norman E Nelson
Manager, Quality Assurance

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