IE Circular No. 80-11, Emergency Diesel Generator Lube Oil Cooler Failures
SSINS No.: 6830
Accession No.:
8002280662
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
May 13, 1980
IE Circular No. 80-11
EMERGENCY DIESEL GENERATOR LUBE OIL COOLER FAILURES
Description of Circumstances:
Within a two week period (August 27 to September 11, 1979), the tube sheets
failed in the lube oil coolers of both emergency diesel generators for
Arkansas Nuclear One (ANO) Unit No. 1. The introduction of water into the
diesel lube oil system resulted in trips of both diesels during surveillance
testings. The diesels were not considered capable of sustained operation.
These events were previously identified to all operating license and
construction permit holders by Information Notice 79-23, Emergency Diesel
Generator Lube Oil Cooler on September 26, 1979. The emergency diesel
generators involved were manufactured by the Electro-Motive Division (EMD)
of the General Motors Corporation and the failures occurred on engines
71-A1-1117 and 71-A1-1130. The failed lube oil coolers were manufactured by
the Young Radiator Company.
An analysis of the failed coolers performed by EMD resulted in the
conclusion that the failures were caused by severe corrosion of the solder
which sealed the tubes to the tube sheets. The corrosion inhibitor in use
at ANO was Calgon CS, a borate-nitrite type inhibitor. The manufacturer of
this type of inhibitor has recommended the use of hard solder in CS treated
systems. EMD does not recommend the use of the Calgon CS since the puddle
solder used in EMD radiators and oil coolers is considered to be soft solder
of a lead-tin composition.
Recommended Action for Licensee's Consideration:
Based on the above, it is recommended that licensees:
1. Verify that the corrosion inhibitor used in cooling water systems of
the emergency diesel generators is compatible with all materials wetted
by the cooling water and the engine manufacturer's specific
recommendations. Also, by means of the engine maintenance history,
verify that the system corrosion inhibitor has been properly monitored
and maintained at the recommended concentration.
2. If Item 1 cannot be successfully performed, the affected components
should be inspected in accordance with the manufacturer's
recommendations.
.
IE Circular No. 80-11 May 13, 1980
Page 2 of 2
No written response to this Circular is required.
If you desire additional information regarding this matter, contact the
Director of the appropriate NRC Regional Office.
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