Morning Report for October 2, 2008

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Concerns with Revised ASTM Standard for Diesel Fuel Oil




License No:

MR Number: H-2008-0007
Date: 10/02/2008


The NRC is issuing this morning report to update NRC management regarding an American Society for Testing and Materials (ASTM) diesel fuel oil standard change that will allow the use of up to 5% biodiesel (B5) in normal diesel fuel oil. The new ASTM standards for biodiesel were approved in June 2008, and changes to fuel oil would likely take effect within 3 to 5 months once the final standards are published. ASTM reportedly issued the new standard (ASTM D975-08a) on October 1, 2008, and it will be available to the public on October 13, 2008.

Regulatory Guide 1.137 "Fuel Oil Systems for Standby Diesel Generators" notes that Appendix B to ANSI N195-1976 should be used as a basis for a program to ensure the initial and continuing quality of fuel oil, as supplemented (in part) by the fuel oil specifications of ASTM D975-77, "Standard Specification for Diesel Fuel Oils". This specification for conventional diesel fuel allows up to 5 percent volume of biodiesel to be blended into compliant diesel fuels. The biodiesel blend must meet all the numeric requirements for diesel fuel properties specified in ASTM D975 and no changes or relaxations were made to accommodate biodiesel. It is important to note the conventional petrodiesel specification can now contain up to 5% biodiesel (B5 blend) without a change to the label.

The 100% biodiesel fuel, also known as "B100", is required to meet ASTM D6751 ("Standard Specification for Biodiesel Fuels (B100) Blend Stock for Distillate Fuels").

Two of the concerns with biodiesel are hydrophilic water attraction and rapid oxidization in storage tanks to form corrosive acids and insoluble polymers. Biodiesel storage can adversely affect components in the emergency diesel generator system and cause clogging of fuel oil filters and other components. Biodiesel can have a cleaning effect that loosens accumulated sediment in storage tanks that previously stored conventional diesel fuel. This loosened sediment can then plug filters and other equipment in the fuel oil system. Diesel fuel manufacturers are recommending that tanks be cleaned before putting biodiesel in them. It is important to recognize these new diesel fuel oil standards are in place and procurement of new fuel oil may affect emergency diesel generator system reliability.

Users need to be aware of the unique properties of the B5 blend because biodiesel has the potential to negatively affect diesel engine performance. The B5 blend is biodegradable and degradation of the fuel supply is accelerated by the presence of water, heat, oxygen, and other impurities. To avoid damage caused by fuel degradation, it is recommended that B5 blend not be stored for a long period of time. Biodiesel will be a problem if proper preparations are not made and the proper additives are not routinely used. Licensees' agreements with fuel suppliers not to deliver B5 biodiesel blend to the plant may still not guarantee delivery of fuel that is free of biodiesel.

From discussion with NRC Region II staff, it appears that licensees are becoming aware of the change to the ASTM standard and have recently identified the potential to receive B5 blend diesel fuel in excess of the previously acceptable limits in a fuel oil shipment without being notified of the increase. Other sites may therefore also be in the early stages of recognition of this problem. NRC staff is considering issuance of an Information Notice on this topic.


Name Office Abbrev Phone No E-Mail
BERNARDO, ROBERT J NRR (301) 415-2621

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