Information Notice 1996-67, Vulnerability of Emergency Diesel Generators to Fuel Oil/Lubricating Oil Incompatibility
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UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
December 19, 1996
NRC INFORMATION NOTICE 96-67: VULNERABILITY OF EMERGENCY DIESEL
GENERATORS TO FUEL OIL/LUBRICATING OIL
INCOMPATIBILITY
Addressees
All holders of operating licenses or construction permits for nuclear power reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert
addressees to a recent finding involving degradation of the power block assembly of two
emergency diesel generators caused by an incompatibility of the lubricating oil with fuel oil
with a low sulfur content. It is expected that recipients will review the information for
applicability and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
DescriDtion of Circumstances
In December 1995, during preoperational testing of a new safety-related emergency diesel
generator (EDG), test engineers for the licensee, Baltimore Gas and Electric Company
(BGE), at the Calvert Cliffs Nuclear Power Plant, noted sporadic spikes in crankcase
pressure and lubricating oil seeping out from the crankshaft seal. The engine was shut down
and BGE conducted a boroscopic inspection of the unit. One cylinder showed indications of
abnormal wear. The cylinder liner, piston, and piston rings were removed for analysis and
replaced with a spare set. The testing program resumed, with normal crankcase parameters
being indicated.
The test program for the safety-related EDG was completed on January 8, 1996. Several
days later, during a scheduled 2-year maintenance inspection, BGE found four cylinders with
heavy carbon-like deposits on the pistons and behind the piston rings and evidence of
abnormal scuffing on the cylinder liners. On further inspection, all the cylinders exhibited
some degree of similar degradation, including the replacement cylinder. BGE then inspected
a second new EDG that had been installed as a backup power supply in 1995 for station
blackout. One cylinder on the station blackout engine exhibited degradation similar to that of
the safety-related EDG. Upon disassembly, excessive carbon deposition was found in all
cylinders.
9612160113 G96R 7-00
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December 19, 1996 Discussion
Calvert Cliffs Nuclear Power Plant comprises two Combustion Engineering reactors with three
EDGs, one dedicated to each unit and the third a "swing" EDG, that automatically loads onto
the accident unit. In 1989, BGE initiated a modification to upgrade Calvert Cliffs emergency
electrical system and meet the requirements of the station blackout rule. The modification
included the installation of one safety-related EDG (giving each unit two dedicated EDGs)
and one nonsafety-related EDG capable of powering any of the four safety-related 4-kV
emergency electrical buses (for station blackout purposes). The new EDGs are basically
identical, each with two engines in tandem with the generator between the engines. The
EDGs were manufactured by Societ6 Alsacienne de Constructions M6chaniques de Mulhouse
(SACM) and have a nominal continuous rating of 5400 kW.
When the cylinder degradation was found, BGE assembled a root cause analysis team, which
included persons with recognized industry expertise. The team developed three potential
causes for the diesel power block degradation: components not to design specifications, improper operation of the engines, and lubricating oilfuel oil incompatibility. The first
possibility was ruled out by metallurgical and dimensional analysis and the second from
discussions with SACM and other operators of SACM diesel generators. The team
concluded that the lubricating oil used was incompatible with low sulfur content fuel.
The BGE team found that lubricating oil compatibility depends, in part, on the type of fuel
being burned, as the lubricating oil contains an additive package that neutralizes the products
of combustion, most importantly sulfuric acid, to prevent engine corrosion. The lubricating oil
originally selected was an American Petroleum Institute (API) CD-grade synthetic oil. For the
fuel oil used in the engines at that time, the specification was that the sulfur content was not
to exceed 0.30 percent. In early 1995, the supplier of fuel oil to Calvert Cliffs switched to
fuels with sulfur contents of 0.05 percent or less in order to meet new Environmental
Protection Agency requirements intended to reduce sulfuric acid emissions. With the
reduced amount of sulfur, there would be more unreacted additive in the lubricating oil, resulting in the formation of deposits when some of the oil was bumed. These deposits built
up behind the piston rings, forcing the rings to extrude and come into contact with the
cylinder liner wall, resulting in scuffing.
After the problem was identified, BGE rebuilt the safety-related EDG with new cylinder liners, pistons, and piston rings. On the basis of the findings of the root cause analysis team, the
safety-elated EDG was supplied with a different lubricating oil, which is an API CG-4 grade
mineral-based oil. A series of acceptance tests were then run to validate the root cause.
The safety-related EDG was inspected after test runs totaling about 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> and no
abnormal conditions were found. The station blackout EDG was then refurbished, tested, and inspected, and the results were identical to those for the safety-related EDG.
Another characteristic of synthetic lubricating oil was identified during the review of this event.
Synthetic oils contain diester additives required to improve solubility of oil additives. In diesel
IN 96-67 December 19, 1996 engines with low oil sump temperatures, water may accumulate in the sump because the
temperature is too low to vaporize it. This water might cause hydrolysis of the diesters and
the resulting acids would react with calcium in the additive to form insoluble compounds
(soaps). These compounds may clog filters and degrade performance of a diesel engine.
This information notice requires no specific action or written response. If you have any
questions about the information in this notice, please refer to the technical contacts listed
below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Kirke Lathrop, Region I
(410) 586-2626 Email: hkl@nrc.gov
Krzysztof Parczewski, NRR
(301) 415-2705 Email: kip@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
KI %&
Attachment
December 19, 1996 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
96-66
96-65
96-64
96-63
96-62
96-61
Recent Misadministrations
Caused by Incorrect Cali- brations of Strontium-90
Eye Applicators
Undetected Accumulation
of Gas in Reactor Coolant
System and Inaccurate
Reactor Water Level
Indication During Shutdown
Modifications to Con- tainment Blowout Panels
Without Appropriate
Design Controls
Potential Safety Issue
Regarding the Shipment
of Fissile Material
Potential Failure of the
Instantaneous Trip Function
of General Electric RMS-9 Programmers
Failure of a Main Steam Safety
Valve to Reseat Caused by an
Improperly Installed Release
Nut
12/13/96
12/11/96
12/10/96
12/05/96
11/20/96
11/20/96
All U.S. Nuclear
Regulatory Commission
Medical Use Licensees
authorized to use
eye applicators
All holders of OLs
or CPs for nuclear
power reactors
All holders of OLs
or CPs for nuclear
reactors
All U.S. Nuclear
Regulatory Commission
licensees authorized
to possess special
nuclear material in
unsealed quantities
greater than a critical
mass
All holders of OLs
and CPs for nuclear
power plants
All holders of OLs or
CPs for nuclear power
reactors
OL = Operating License
CP = Construction Permit
IN 96-67 December 19, 1996 engines with low oil sump temperatures, water may accumulate in the sump because the
temperature is too low to vaporize it. This water might cause hydrolysis of the diesters and
the resulting acids would react with calcium in the additive to form insoluble compounds
(soaps). These compounds may clog filters and degrade performance of a diesel engine.
This information notice requires no specific action or written response. If you have any
questions about the information in this notice, please refer to the technical contacts listed
below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
original signed by
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Kirke Lathrop, Region I
(410) 586-2626 Email: hkl@nrc.gov
Krzysztof Parczewski, NRR
(301) 415-2705 Email: kipenrc.gov
Attachment: List of Recently Issued NRC Information Notices
Tech Editor reviewed 11/13/96 A *a C4't J-- 6J cZ'JAcC4Lr
DOCUMENT NAME: 96-67.IN
- SEE PREVIOUS CONCURRENCES
OFFICE
Contacts
C/EMCB:DE
C/PECB:DRPM
D/DRPl
l
NAME
KLathrop*
JStrosnider*
AChaffee*
TM
KParzewski*
DATE
11/21/96
111/21/96
12/12/96
120Y96 II5 PD C)
UOicial Kecord Copyr
4xlk
10 A-'J6
IN 96-xx
December xx, 1996 engines with low oil sump temperatures, water may accumulate in the sump because the
temperature is too low to vaporize it. This water might cause hydrolysis of the diesters and the
resulting acids would react with calcium in the additive to form insoluble compounds (soaps).
These compounds may clog filters and degrade performance of a diesel engine.
This information notice requires no specific action or written response. If you have any
questions about the information in this notice, please refer to the technical contacts listed
below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Kirke Lathrop, Region I
(410) 586-2626 Email: hkl@nrc.gov
Krzysztof Parczewski, NRR
(301) 415-2705 Email: kip@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
Tech Editor reviewed 11/13/96 DOCUMENT NAME: G:JRT\\EDG.INS
- SEE PREVIOUS CONCURRENCES
OFFICE
Contacts
C/EMCB:DE
C/PECB:DRPM
NAME
KLathrop*
JStrosnider*
AChaffee
TMzinl
KParzewski*
lI
_
DATE
11/21/96
11/21/96
1.Vlt/96
124096
MIciaal Kecora C.opy
M
- &M-.)
r Ac0
4 IN 96-xx
November xx, 1996 abnormal conditions were found.
The station blackout EDG was then refurbished, tested and inspected, with identical results as the safety-related EDG.
Another undesirable characteristic of synthetic lubricating oil was identified
during the review of this event. Synthetic oils contain diester additives
required to improve solubility of oil additives. In diesel engines with low
oil sump temperatures, water may accumulate in the sump because the temperature
is too ow to vaporize it. This water may cause hydrolysis of the diesters and
the resulting acids react with calcium in the additive to from insoluble
compounds (soaps). These compounds may clog filters and degrade performance of
a diesel engine.
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please refer to
the technical contact listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical Contact:
Kirke Lathrop, RI
(410) 586-2626 Internet:hkl@nrc.gov
Krzysztof Parczewski, NRR
(301) 415-2705 Internet:kip@nrc.gov
Attachment:
1. List of Recently Issued NRC Information Notices
Tech Editor reviewed 11/13/96
47 DOCUMENT NAME:
G:\\JRT\\EDG.INS 1 OFFICE
Contacts
C/EMC
E
.DC/PECB:DRPM
D/D
E KLathro'p/A'
AChaffee
___
__
KParzewsk iV
F._
_
_
_
_
_
_
_
_
_
_
_
DATE
11/h3/96
11/P.J/96
11/
/96
1+/-/93/96
Official Record Copy
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