Information Notice 2006-22, New Ultra-Low-Sulfur Diesel Fuel Oil Could Adversely Impact Diesel Engine Performance
| ML062710079 | |
| Person / Time | |
|---|---|
| Issue date: | 10/12/2006 |
| From: | David Beaulieu NRC/NRR/ADRA/DPR/PGCB |
| To: | |
| Timothy Mitts, NRR/DIRS/IOEB | |
| References | |
| IN-06-022 | |
| Download: ML062710079 (6) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001 October 12, 2006 NRC INFORMATION NOTICE 2006-22: NEW ULTRA-LOW-SULFUR DIESEL FUEL OIL
COULD ADVERSELY IMPACT DIESEL ENGINE
PERFORMANCE
ADDRESSEES
All holders of operating licenses for nuclear power reactors, except those who have
permanently ceased operations and have certified that fuel has been permanently removed
from the reactor vessel.
PURPOSE
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to alert
licensees to the potential for new ultra-low-sulfur diesel (ULSD) fuel oil to adversely impact
engine performance. It is expected that recipients will review the information for applicability to
their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this IN are not NRC requirements; therefore, no specific action or
written response is required.
DESCRIPTION OF CIRCUMSTANCES
In January 2001 and in June 2004, the U.S. Environmental Protection Agency (EPA) finalized
the Clean Diesel Trucks and Buses Rule and the Clean Nonroad Diesel Rule, respectively, with
more stringent standards for new diesel engines and fuels
(http://www.epa.gov/oms/regs/fuels/diesel/diesel.htm). The EPA rules require a reduction in the
sulfur content of highway diesel fuel from its current level of 500 parts per million (ppm) (low
sulfur diesel, or LSD) to 15 ppm (ULSD). Refiners were required to start producing the
cleaner-burning diesel fuel ULSD, for use in highway vehicles beginning June 1, 2006. The
EPA requires sulfur reductions for land-based nonroad diesel fuel to be accomplished in two
steps, with an interim step from currently uncontrolled levels to a 500 ppm cap starting in
June 2007 and the final step to 15 ppm in June 2010. Although the EPA requirements for the
15 ppm ULSD do not take effect until 2010 for nonroad diesel fuel, several nuclear power plant
licensees have received shipments of ULSD. The California Air Resources Board regulations
require that all California users of diesel fuel oil transition to ULSD fuel oil by June 1, 2006.
Some licensees have already received (and all licensees will eventually receive) ULSD fuel oil
from petroleum product refiners, distributors, and wholesalers and may have started using this
fuel in diesel engines that provide functions important to safety. Examples of diesel engines
providing functions important to safety include: Emergency diesel generators (EDGs), diesel- driven fire pumps, diesel-driven auxiliary feedwater pumps, diesel-driven essential service water
makeup pumps, diesel-driven instrument air compressors, security diesel generators, safe
shutdown facility diesel generators, diesel generators for emergency preparedness and
response functions, and station blackout diesel generators.
There are several diesel fuel properties other than sulfur concentration that change as a result
of moving to ULSD that may adversely effect the engine performance including:
Energy Content
In general, the processing required to reduce sulfur to 15 ppm also reduces the aromatics
content and density of diesel fuel, resulting in a reduction in volumetric energy content
(BTU/gallon). The expected reduction in energy content is 1.2 percent or more. Less energy
content of the fuel can reduce the instantaneous output rating of the diesel engine. The
reduced output rating may be less than the value specified in the plants design and licensing
basis, potentially rendering the diesel inoperable.
The reduced energy capacity of the ULSD may result in increased fuel consumption such that
the onsite diesel fuel storage capacity for the emergency diesel generators may be insufficient
to satisfy the plants design and licensing basis for diesel operation duration before offsite
replenishment is needed.
The reduced energy capacity may also lengthen the amount of time needed for the emergency
diesel generators to reach the required speed and voltage.
Fuel Particulate Build-up Increases
Additives to increase lubricity and to inhibit corrosion used by different refineries and wholesale
suppliers can react or become unstable in storage, which can result in increased fuel
particulates that may foul or plug filters and fuel injection equipment, and can affect suitability of
some testing methods. Some nuclear plant licensees using ULSD have observed an increase
in the rate of particulate buildup in samples from their diesel fuel oil storage tanks.
Fuel System Seal Leaks
Non-nuclear industry operating experience using ULSD shows an increased incidence of fuel
system leaks at points where elastomers (O-rings) are used to seal joints, with most leaks
occurring at the fuel pump and injectors. The evidence to date suggests the problem is linked
to a reduction in the aromatics content of the ULSD which affects seal swelling, as does seal
material and age of the material.
Compatibility with Lubricating Oil
As discussed in NRC IN 96-67, Vulnerability of Emergency Diesel Generators to Fuel
Oil/Lubricating Oil Incompatibility, lubricating oil contains an additive package that neutralizes
the products of combustion, most importantly sulfuric acid, to prevent engine corrosion. With a reduced amount of sulfur, there is more unreacted additive in the lubricating oil, which may
result in the formation of deposits when some of the oil is burned. These deposits can build up
behind the piston rings, forcing the rings to extrude and come into contact with the cylinder liner
wall, resulting in scuffing.
Microbial Growth
Diesel fuel that was desulfured at the refinery through hydrocracking (versus hydrotreatment)
may have a greater propensity for microbial growth due to an increased concentration of
n-alkanes (linear molecules).
Incompatible Metals
There are no known compatibility issues with aluminum, carbon steel, stainless steel, and
bronze. However, copper and zinc are incompatible with ULSD because both are oxidative
catalysts that will accelerate the formation of sediments, gels, and soaps (American Society for
Testing and Materials (ASTM) D975, Appendix X2.7.2).
Lubricity
Lubricity is a measure of the fuels ability to lubricate and protect the various parts of the
engines fuel injection system from wear. The processing required to reduce sulfur to 15 ppm
also removes naturally-occurring lubricity agents in diesel fuel. Rotary and distributor type fuel
pumps are completely fuel lubricated resulting in high sensitivity to fuel lubricity. Refiners treat
the diesel fuel with additives on a batch to batch basis to ensure adequate lubricity. Therefore, receipt of ULSD with inadequate lubricity is possible but unlikely.
BACKGROUND
Applicable Regulatory Documents
General Design Criterion (GDC) 17, Electric Power Systems, of Appendix A, General Design
Criteria for Nuclear Power Plants, to Title 10 of the Code of Federal Regulations (10 CFR) Part
50, Domestic Licensing of Production and Utilization Facilities, requires that an onsite electric
power system and an offsite electric power system be provided to permit functioning of
structures, systems, and components important to safety. In addition, GDC 17 contains
requirements concerning system capacity, capability, independence, redundancy, availability, testability, and reliability. Appendix B, Quality Assurance Criteria for Nuclear Power Plants and
Fuel Reprocessing Plants, to 10 CFR Part 50 establishes overall quality assurance
requirements for the design, construction, and operation of structures, systems, and
components important to safety. Regulatory Guide (RG) 1.137, Revision 1, Fuel Oil Systems for Standby Diesel Generators
dated October 1979, describes a method acceptable to the NRC staff for complying with the
Commissions regulations regarding diesel fuel oil systems for standby diesel generators and
assurance of adequate diesel fuel oil quality. RG 1.137 states that Appendix B to American
National Standards Institute (ANSI) N195-1976 should be used as a basis for a program to
ensure the initial and continuing quality of diesel fuel oil as supplemented by eight additional
provisions described in the RG for maintaining the properties and quality of diesel fuel oil.
Related NRC Generic Communications
NRC IN 96-67, Vulnerability of Emergency Diesel Generators to Fuel Oil/Lubricating Oil
Incompatibility, dated December 19, 1996. This IN alerted addressees to a finding involving
degradation of the power block assembly of two EDGs caused by an incompatibility of the
lubricating oil with a low-sulfur-content diesel fuel oil.
NRC IN 91-46, Degradation of Emergency Diesel Generator Fuel Oil Delivery Systems, dated
July 18, 1991. This IN alerted addressees to potential inoperability of multiple EDGs resulting
from common cause degradations: (1) degraded diesel fuel oil delivery systems and (2) failure
to meet technical specification (TS) testing requirements intended to detect potentially- degraded quality of the diesel fuel oil stored onsite.
NRC Generic Letter (GL) 83-26, Clarification of Surveillance Requirements for Diesel Fuel
Impurity Level Tests. This GL provided licensees revised surveillance provisions for diesel fuel
oil impurity level tests to clearly reflect the relationship between the Standard TS testing
requirements for diesel fuel oil impurity levels; guidance given in RG 1.137, Revision 1, and
ANSI N195-1976 (ASTM D270, ASTM D975 and ASTM D2274); and the NRC staff review
performed in accordance with Standard Review Plan Sections 9.5.4 through 9.5.8.
DISCUSSION
In January 2001 and in June 2004, the EPA finalized the Clean Diesel Trucks and Buses Rule
and the Clean Nonroad Diesel Rule, respectively, with more stringent standards for new diesel
engines and fuels that require a reduction in diesel fuel sulfur content to 15 ppm. Some
licensees have already received, and all will eventually receive, this ULSD. As described
above, the ULSD has a number of properties that have the potential to degrade or render
inoperable the associated diesel engine or may create a condition that is inconsistent with
current plant design and licensing bases. This ULSD issue is of particular concern because it
effects all licensee diesel generators that are safety-related and/or important to safety, thereby, presenting a possible common mode failure. Licensees can evaluate the potential impacts of
ULSD and can take measures to ensure the plant is consistent with the current design and
licensing basis and prevent the diesels from being rendered inoperable or significantly
degraded.
CONTACT
This information notice requires no specific action or written response. Please direct any
questions about this matter to the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Ho K. Nieh, Acting Director /RA/
Division of Policy and Rulemaking
Office of Nuclear Reactor Regulation
Technical Contacts: Patrick Finney, RI Robert Wolfgang, NRR/DCI
610-337-5344 301-415-1624 E-mail: pwf@nrc.gov E-mail: rjw1@nrc.gov
Timothy Mitts, NRR/DIRS Max Schneider, RI
301-415-4067 860-447-3170
E-mail: tmm5@nrc.gov E-mail: sms2@nrc.gov
Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under Electronic Reading Room/Document Collections.
CONTACT
This information notice requires no specific action or written response. Please direct any
questions about this matter to the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Ho K. Nieh, Acting Director /RA/
Division of Policy and Rulemaking
Office of Nuclear Reactor Regulation
Technical Contacts: Patrick Finney, RI Robert Wolfgang, NRR/DCI
610-337-5344 301-415-1624 E-mail: pwf@nrc.gov E-mail: rjw1@nrc.gov
Timothy Mitts, NRR/DIRS Max Schneider, RI
301-415-4067 860-447-3170
E-mail: tmm5@nrc.gov E-mail: sms2@nrc.gov
Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under Electronic Reading Room/Document Collections.
Distribution: IN Reading File
ADAMS Accession Number: ML062710079 OFFICE IOEB:DIRS TECH EDITOR BC:NRR:CPTB Ri:DRS:EB3 NRR:DCI
NAME TMitts CBladey (by e-mail) TLiu PFinney RWolfgang
DATE 09/28/2006 09/27/2006 10/03/2006 10/02/2006 09/28/2006 OFFICE PGCB:DPR PGCB:DPR TL:IOEB:DIR BC:PGCB:DPR D:DPR(A)
NAME DBeaulieu CHawes ICJung CJackson HNieh
DATE 10/06/2006 10/10/2006 10/04/2006 10/11/2006 10/12/2006 OFFICIAL RECORD COPY