Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR MATERIALS SAFETY AND SAFEGUARDS
WASHINGTON, D.C. 20555
April 30, 1990
Information Notice No. 90-27: CLARIFICATION OF THE RECENT REVISIONS TO
THE REGULATORY REQUIREMENTS FOR PACKAGING
OF URANIUM HEXAFLUORIDE (UF6) FOR
TRANSPORTATION
Addressees:
All Uranium Fuel Fabrication and Conversion Facilities.
Purpose:
This notice is being issued to review and clarify the significant features
of two recent rulemaking actions which were completed by the U.S. Department
of Transportation (DOT), relating to the regulatory requirements for the
packaging of UF6 for transportation. It is suggested that recipients review
the information here, and consider actions, if appropriate, to preclude
possible problems in the transport of UF6. However, this information does
not constitute new U.S. Nuclear Regulatory Commission (NRC) requirements,
therefore no specific action or written response is required.
Background:
The routine transportation of UF6, both as a non-fissile radioactive
material (depleted and natural uranium, a "low specific activity" [LSA]
material) and as a fissile radioactive material (when containing "greater
than" 1.0 weight percent U-235), constitutes a very significant volume of
radioactive materials transportation in the nuclear fuel cycle, both within
the USA and worldwide. UF6 is packaged for transport in cylinders which
must meet certain inspection, testing and in-service requirements which are
found in the 49 CFR DOT regulations and certain physical standards which are
adopted by reference in those regulations. The primary type of packaging
used are cylinders of steel, nickel, or monel in various diameters ranging
from 1 inch to 48 inches.
For shipments of the unenriched UF6 as an LSA, non-fissile radioactive
material, the cylinders are normally shipped bare, without protective
overpacks. Overpacks are used, however, for the shipment of enriched UF6,
as a fissile material, when the U-235 content exceeds 1.0 weight percent.
The overpacks used are either of the DOT Specifications 20PF or 21PF Series
as prescribed in 49 CFR 178.120 and 178.121 of DOT regulations, or as
authorized in several NRC Certificates of Compliance. (See Attachment 1.)
Most shipments of UF6 are made in exclusive-use highway or rail vehicles,
and in equivalent defined stowage areas or intermodal freight containers
aboard seagoing vessels.
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Before November 1986, the DOT regulations were not specific on the standards
for the cylinders, but rather, referenced the need to use a "strong tight
package" for exclusive-use shipments. For non-exclusive-use shipments, the
cylinders were required to meet the requirements for DOT Specification 7A,
Type A packaging. [The cylinders actually used, however, were in accordance
with industry standards that exist in ANSI N14.1 and/or a Department of
Energy (DOE) document, ORO-651]. On November 17, 1986, DOT issued a new
regulation (49 CFR 173.420) specifying cylinder standards and other
requirements for all shipments of UF6. Several supplemental notices and
amendments were subsequently issued in the Docket HM-166V, with the last
revision of the final rule having been issued on August 29, 1989.
As for the protective overpacks for the cylinders, DOT originally issued its
regulatory specifications for the DOT Specifications 20PF and 21PF series in
1974. Over the years, during the use of these overpacks, increasing
difficulties have been experienced in their use, maintenance and quality
control. The primary difficulty has been with the tendency of the
packagings to collect and retain water within the phenolic foam insulating
medium within the walls of the overpack. Although the presence of this
water is not an immediate safety problem, the water does increase the gross
weight of the packages significantly, and also accelerates corrosion of the
metal and rotting of the wood components of the overpacks. It often tends
to "slosh" out from the drain holes, and sometimes creates considerable
alarm to the public and to carriers, when water (albeit non-radioactive
water) is observed to be leaking from a package marked "RADIOACTIVE" in
commerce. Accordingly, DOE petitioned DOT for rulemaking to amend the DOT
21PF series protective overpack specification, so as to authorize the use of
an improved design that would correct the deficiencies. A notice of
proposed rulemaking was issued in August 1984, with the final rule issued on
September 20, 1988 (Docket HM-190). During the interim period, between the
notice and final rule, several NRC-licensee shippers of UF6 in protective
overpacks applied for and received NRC certificates of compliance
authorizing use of non-DOT specification, improved overpacks.
Discussion:
Attachments 2 and 3 are chronological summaries of the two recently
completed DOT rulemaking dockets relating to UF6 packaging and
transportation. Attachment 2 summarizes the Docket HM-166V on cylinder
requirements, and Attachment 3 summarizes the Docket HM-190 rule changes on
the DOT Specification 21PF series of protective overpacks. Attachment 1 is
a summary of the present status of several NRC certificates of compliance
for overpacks that are similar to the DOT Specification 21PF overpacks.
Discussion of each of these areas follows:
CYLINDERS
The net effect of the cylinder rulemaking imposed by the new 49 CFR 173.420
in Docket HM-166V has been to formalize, as regulatory requirements, the use
of cylinders which have already been in use for many years, pursuant to
certain industry standards, as well as other requirements (e.g.,
requirements for UF6
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to be in solid form and specified volumetric fill limits). In carrying out
the rulemaking, however, several difficulties were observed (e.g., the
method of cleaning for other than new cylinders, provisions for use of
existing cylinders, etc.), as evidenced by the series of eight notices and
amendments between April 1986 and April 1989. It is noted that the final
rule also formalizes the use of the DOT Class 106A multiunit tank car tank
(which is actually referred to in the industry as the Model 30A cylinder).
However, both of the published industry standards -- ANSI N14.1-1987 and
ORO-651, Rev. 5 -- have taken the position that the Model 30A cylinder is
obsolete, and will be replaced by the Model 30B. In effect, therefore, DOE
has stated that it will no longer fill Model 30A cylinders at its gaseous
diffusion facilities after December 31, 1992.
For any existing cylinder constructed before the new rules, continued use is
authorized, provided that it was designed, inspected, tested, and marked in
accordance with the 1987, 1982 or 1971 version of ANSI N14.1, in effect at
the time of construction; or for cylinders manufactured before June 30,
1987, Section III, Div. I of the ASME Code.
PROTECTIVE OVERPACKS
The net result of the rulemaking in Docket HM-190 has been to upgrade the
regulatory requirements for the fabrication, maintenance, and use of the DOT
Specification 21PF-1 protective overpacks. The key dates for compliance
with these new rules are:
April 1, 1989--Construction of all new overpacks must be in accordance
with DOT Specification 21PF-1B after this date, and these overpacks
marked as such; and
April 1, 1991--Refurbishment and conversion of all existing overpacks
to the requirements of DOT Specification 21PF-1A must be accomplished
and these overpacks marked as such.
During the period between April 1, 1989 and April 1, 1991, therefore, the
use of unmodified DOT Specification 21PF-1 overpacks continues to be
authorized. However, both the owners of unmodified overpacks and the U.S.
enrichment plants which fill the cylinders for subsequent loading into the
overpacks are taking steps to perform quality control inspections of the
overpacks to correct deficiencies, such as containing excessive water. (See
Attachment 4). If such inspections reveal excessive water, measures are
being taken to remove the overpack from service for drying, resealing,
gasket replacement, or other necessary refurbishment, or if necessary, for
disposal. The U.S. enrichment plants are also requesting the owners of
unmodified overpacks to supply them with acceptance certifications stating
that the quality control inspections and other maintenance procedures have
been accomplished.
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NRC CERTIFICATES OF COMPLIANCE
During the period of the Docket HM-190 rulemaking, several U.S. owners of
protective overpacks for 30" cylinders obtained certificates of compliance
from the NRC to authorize the use of overpacks of improved design. These
are summarized in Attachment 1. A comparison of the specifics of the DOT
Specification 21PF-1A and 1B requirements with these certificates indicates
that there will still remain a need for the certificates, in that there are
substantial differences between, for example, the Model UX-30 (USA/9234/AF)
and the NCI-21-PF-1 (USA/9196/AF) and the DOT specifications.
Robert F. Burnett, Director
Division of Safeguards
and Transportation
Office of Nuclear Materials Safety
and Safeguards
Technical Contact: A. W. Grella, NMSS
(301) 492-3381
Attachments:
1. NRC Certificates of Compliance for UF6 Overpacks
2. Chronology of UF6 Cylinder Rulemaking (HM-166V)
3. Chronology of UF6 Overpack Rulemaking (HM-190)
4. "Interim Inspection and Sealing Procedures for DOT-21PF-1 Overpacks"
5. List of Recently Issued NMSS Information Notices
6. List of Recently Issued NRC Information Notices
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