ML20070S176
| ML20070S176 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie, Susquehanna, 05000000 |
| Issue date: | 12/15/1982 |
| From: | Karr B HEVI-DUTY/NELSON (FORMERLY NELSON ELECTRIC CO.) |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| REF-PT21-82-750-000 PT21-82-750, PT21-82-750-000, NUDOCS 8302040288 | |
| Download: ML20070S176 (3) | |
Text
. _,
p' o-3eV fa-750-sao em N
NELE ON ELECTAIC 52 C BDx 7P6 TULbh O K L A ** C M A 7d909 88 MON E 9 9 9.E P 7-S 5 30 - TELEA A92d&d December 15, 1982 John Collins Regional Administrator U.S NUCLEAR REGULATORY CO.911SS10N Region IV 611 Ryan Placa Drive Arlington, TX 76011
Dear Sir,
On December 1, 1982, I provided your office with written notification of a potential defec.t pertinent to nuclear orders wherein 10 CFR Part 21 was applicable.
Within that letter, it was stated that whenever a detailed report of the failure mode became prevalent, it would be forwarded to your office as well as to the affected nuclear facilities.
On December 14, 1982, I received the detailed failure analysis report from Nelson Electric's Director of Engineering.
Tne report's analysis data was obtained through a coordinated investigating effort involving our Engineering department and an outside analytical laboratury ib Tulsa, Oklahoma.
To extrapolate on the information supplied to you in my letter of notification, utilizing subsecuent information prevalent within the failure analysis report, the following is offered:
1.
Problem The potentially defective part is a stamped tubing sleeve, (GA-1213 and GA-1234) that is used to house a hot-cold electrical splice in our Inconel M. I.
heating cable assemblies.
8302040288 821215 PDR ADOCK 05000388
/E/9
(q kE NELCON ELECT AIC
== *
- D We developed a reject pattern in our inspection of this sleive which indicated water entry during our water soak testing.
(The normal rej ect mode fo -
this fitting is not water leakage but dielectric spacing error.)
II.
Problem Analysis These sleeves were found to have too high a residual stress present in their finished condition.
The high residual stress reacted with the silver solder at the brazing temperatures (13000 - 16000F) to create a stress crack in the sleeve material (Inconel 600).
The individual cable assembler's techniques of preheating the fitting, fluxing and silvering the sleeve vary.
Hence many of the assemblies never received the right combination of time and temper-ature during the brazing operation to cause the s :ress crack to develop.
These fittings are not in danger of future cracking since the operational temperatures (4000 - 5000F) are well below the reaction temperature range (13000 - 16000F).
We reviewed the entire production cycle of each batch of sleeves since the prototype work was done.
The source of the higher than normal stresses that caused the cracking appears to have come from a batch of Inconel s trip (used to make the tube) that was not dead soft annealed.
III.
Corrective Acticr Takcr - Immediate A.
Selson Electric has schedu_ led a Field Service Engineer into each nuclear facility affected to check questionable circuits.
It is antici-pated this effort will be completed by the end of January, 1983.
B.
This part, used on products fabricated but unshipped, will undergo dye penetrant examin-ation to verify no stress cracks are prevalent on hot-cold splice sleeves of M.I. heating cable assemblies.
4 6
m NELCON ELECT AIC e C.
Existing inventory of this splice sleeve fitting has been purged and will be properly annealed and pickled before being released for ese on finished cable assemblies.
IV.
Corrective Action Taken to Preclude Recurrence To preclude recurrence of this type of deficiency on future runs, Nelson Electric has included an annealing step for the fittings within its f abrica-tion cycle, after the stamping process.
V.
Conclusion This analysis and investigation of the potential problem proved it to be confined to a particular q batch of material used for a brief and determined
~'T /
period cf time.
Our traceability and record keeping systems enabled us to determine which heater cable a'ssemblies requiring corrective action had shipped to the j ob sites.
We were also able to take appro-priate in-house corrective action measures.
The magnitude of the problem was not to the parameters it was originally thought to be.
We will continue to monitor company performance for adherence to established quality program requirements and report any applicable noncompliance to the Nuclear Regula-tory Co==ission as pertinent to 10 dFR Part 21.
Should anv further information be desired or additional actions b'e required, please cbntact this office.
Bill Karr Director of Quality Assurance cc:
Dir.
Office of Insp. ari Enforcement - NRC (3) copies St. Lucie, Unit 2 - Florida Power & Light - Jeff Austin (1)
Susquehanna, Unit 2 - Penn Power & Light - Phil Brady (1)
Sidal Aluminum Corp - Joe Rice (1) t.
E