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Licensed Fuel Facility
Status Report - Inventory Difference Data
July 1, 2001 - June 30, 2002 (NUREG-0430)
Contents
Table of Contents
Publication Information
Manuscript Completed: September 2003
Date Published: October 2003
T. Pham
Division of Nuclear Security
Office of Nuclear Security and Incident Response
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555-0001
Abstract
The U.S. Nuclear Regulatory Commission is committed to an annual publication of licensed fuel
cycle facility inventory difference data, following Agency review of the information and
completion of any related investigations. Information in this report includes inventory difference
results for active fuel fabrication facilities possessing more than one effective kilogram of
special nuclear material.
ABBREVIATIONS/ACRONYMS
AI |
Active inventory |
BI |
Beginning inventory |
C.L. |
Confidence level |
CFR |
Code of Federal Regulations |
DQ |
Detection quantity |
DT |
Detection threshold |
EI |
Ending inventory |
FKG |
Formula kilogram(s) |
HEU |
High-enriched uranium |
ID |
Inventory difference |
LEU |
Low-enriched uranium |
MUF |
Material unaccounted for |
NRC |
Nuclear Regulatory Commission |
Pu |
Plutonium |
SEID |
Standard error of an inventory difference |
SM |
Source material |
SNM |
Special nuclear material |
SSNM |
Strategic special nuclear material |
U-233 |
Uranium-233 |
U-235 |
Uranium-235 |
Pu-238 |
Plutonium-238 |
Pu-239 |
Plutonium-239 |
Pu-241 |
Plutonium-241 |
1. INTRODUCTION
The Licensed Fuel Facility Status Report (NUREG-0430) is a periodic
report that provides
inventory information on NRC-licensed fuel cycle facilities. The information
included in
NUREG-0430 consists of a tabulation of inventory difference data for
all active fuel cycle
facilities, a list of acronyms, and a glossary of various term definitions
used throughout this
publication. The first semiannual issue of NUREG-0430 was published on
May 16, 1978. With
the second issue of Volume 9 published in April 1990, the NRC changed
to a one-year interval
because most of the licensed fuel cycle facilities were on an annual
inventory frequency.
All fuel cycle facilities authorized to possess and use more than one
effective kilogram of
special nuclear material (SNM) are required to report the results of
each physical inventory to
the NRC pursuant to 10 CFR 74.17. This report contains a tabulation of
physical inventory
results generated during the one-year period from July 1, 2001, to June
30, 2002, for the seven
active fuel fabrication facilities and two active uranium enrichment
facilities (gaseous diffusion
plants).
2. DISCUSSION
The NRC uses a graded approach in applying safeguards requirements for
all licensed
facilities, depending on the strategic significance of the SNM authorized
for possession, and the
level and frequency of monitoring programs required for timely detection
of losses. It is
important to distinguish between the low strategic significance of low-enriched
uranium (LEU)
and the higher strategic significance of high-enriched uranium (HEU)
and plutonium. LEU
materials used to fabricate fuel assemblies for commercial power reactors
are enriched to a
level of one to 5 percent in the U-235 isotope. At this enrichment level,
and under certain
conditions, the uranium can sustain a chain reaction, but cannot generate
a nuclear explosion
regardless of its quantity and configuration.
NRC safeguards requirements covering LEU reflect its low strategic significance.
They include
a formal structured system for material control and accounting and graded
physical protection
measures. Because of the higher strategic significance of HEU and plutonium,
which under
certain circumstances could be used for the fabrication of a nuclear
explosive device, the NRC
requires HEU licensees to provide substantial physical protection of
these materials including
features such as barriers, intrusion alarms, armed guards, and offsite
police response
capability. Additionally, more rigorous controls and accounting programs
are imposed,
including internal systems to control the movement of strategic SNM and
to monitor its
presence.
Licensees authorized to have significant quantities of strategic SNM (i.e., HEU, plutonium, or
uranium-233) are required to conduct physical inventories at least every six months, and
facilities authorized to possess and use more than one effective kilogram of SNM of moderate
strategic significance are required to conduct physical inventories at least every nine months,
whereas licensees whose holdings are restricted to SNM of low strategic significance perform
physical inventories every twelve months.
At each physical inventory, the quantity of SNM on hand, as physically determined, is compared
to the quantity of SNM on hand as indicated by the facility’s accounting records (or book
inventory). The difference between the physical inventory and the book inventory is called
Inventory Difference (ID), also sometimes referred to as material unaccounted for (MUF).
ID values resulting from physical inventories conducted at facilities authorized to possess and
use significant quantities of strategic SNM are classified as “CONFIDENTIAL National Security
Information” until at least six months have elapsed since the ID was derived, and any excessive
ID has been investigated and resolved. For this reason, the ID data are not published until the
six months have elapsed.
Non-zero IDs, both positive and negative, result from a combination of factors such as
measurement variability, measurement mistakes, changes in the quantity of unmeasured
equipment holdup, and record keeping errors. An unmeasured loss, either accidental or
deliberate, or theft would cause an unidirectional impact on determining ID (e.g., mathematically
increase a positive ID or decrease a negative ID). Generally, the more complex a facility’s
process operations are, especially when dealing with chemical operations, the greater the
potential for uncertainty associated with an ID value. Although an ID larger than its overall
measurement uncertainty may signal an abnormal situation, the fact that an ID falls within its
associated limit of error, even a zero ID value, provides no automatic or conclusive proof that a
loss or theft of SNM has not occurred. Therefore, the NRC relies on information provided not
only by the material accounting system, but also by the internal control system, the physical
protection system, NRC inspections and evaluations, plus NRC and licensee investigations.
Both the book inventory and the physical inventory are based on measured values. Thus, both
are subject to measurement uncertainty. The total uncertainty associated with an ID value is
designated by the standard error of the inventory
difference (SEID), which is a 67 percent
confidence level uncertainty. Therefore, in the absence of recording errors, unmeasured
losses, and material theft or diversion, the expected value of an ID is zero plus or minus SEID,
depending on the desired confidence level.
Active inventory is the quantity of material measured for accountability purposes since the last
physical inventory, and for throughput-dominated facilities is essentially equal to twice the
throughput for the inventory period. The concept of SEID is a method that the NRC and
licensees subject to either 10 CFR 74.31, 74.33, 74.43, or 74.59 use to determine the
significance of the ID. For 10 CFR 74.31 and 74.33 licensees (Category III facilities), ID must
exceed its threshold quantity, which represents a site-specific value that is considerably larger
than SEID, before investigative actions are required. For 10 CFR 74.43 licensees (Category II
facilities) and 74.59 licensees (Category I facilities), investigative actions are required whenever
an ID exceeds both specific quantities and three times SEID. In addition, an ID that exceeds its
associated SEID may be an indication of processing problems, inaccurate measurements,
bookkeeping errors, or a loss or theft of material. The NRC accordingly requires the licensees
to take increasingly stronger investigative actions depending on how much the ID exceeds both
SEID limits and specific quantities.
3. CONCLUSION
The IDs for this reporting period (July 1, 2001, through June 30, 2002) are listed in the
“Tabulation of Inventory Differences” that begins on page 8 of this report. An explanation of the
significance and, when appropriate, the contributing factor(s) for IDs deemed excessive are
included in the last column of the table. A total of 15 ID values was generated during this
reporting period; 6 pertained to HEU, and 9 pertained to LEU materials. All of the IDs were
either within regulatory limits or expected ranges except three IDs exceeded its regulatory limits
The excessive IDs were either ID gains or losses resulting from measurement biases of
heterogenous scrap materials. These IDs were investigated by the licensee and no anomalous
condition was identified. No enforcement or regulatory action was required.
4. DEFINITION OF TERMS
Active Inventory (AI): The sum of beginning inventory
(BI), additions to inventory (A), removals from inventory (R), and
ending inventory (EI), after all common terms have been totally excluded.
A common term is any nuclear material value (or item) that appears
in both BI and EI, or both BI and R, or both A and R, or both A and
EI, with both values derived from the same measurement (or combination
of measurements), and thus does not contribute to the uncertainty
associated with the current period inventory difference. The active
inventory is used as an indicator of processing throughput and/or
measurement activity.
Depleted Uranium: Any uranium-bearing material whose combined
U-233 plus U-235 isotopic content is less than 0.70 percent by weight
(relative to total uranium element content).
Detection Quantity (DQ): A site-specific SNM quantity for
Category III licensees whose processing activities are limited to SNM
of low strategic significance. The DQ is normally a function of an
annual throughput, but for low-throughput LEU facilities, the DQ need
not be less than 25 kilograms of U-235. The DQ can also be described
as a goal quantity, the loss or theft of which must be detected with
a 90 percent or better probability, whenever a physical inventory is
taken.
Detection Threshold (DT): An ID alarm limit for Category
III licensees that will be exceeded (with 90 percent or higher probability)
by an ID (resulting from the taking of a physical inventory) whenever
there has been an actual loss of a detection quantity. The DT is a
function of both the DQ and SEID, as shown in the following equation:
DT = DQ - 1.3 (SEID)
Effective Kilogram of SNM: (1) For plutonium and U-233, their
weight in kilograms; (2) for uranium with an enrichment in the isotope
U-235 of 1.00 percent (0.01 weight fraction) and above, its element
weight in kilograms multiplied by the square of its enrichment expressed
as a decimal weight fraction; and (3) for uranium with an enrichment
in U-235 below 1.00 percent, but above 0.71 percent, its element weight
in kilograms multiplied by .0001.
-
Fissile Isotope: A nuclide species that is capable of giving
rise to a self-sustaining chain reaction (of a nuclear fission) when
present in sufficient mass and concentration. U- 233, U-235, Pu-239,
and Pu-241 are the only fissile nuclides contained in "special
nuclear material" (SNM), which also consists of other uranium and plutonium
isotopes.
-
Formula Kilogram (FKG): 1,000 formula grams of SSNM computed
by the following equation:
Grams = (grams U-235 contained in HEU) + 2.5 (grams U-233) +
2.5 (grams plutonium)
Formula Quantity: SSNM in any combination in a quantity of
5,000 formula grams or more, as computed by the same equation as given
above in definition No. 11.
NOTE: In unirradiated form, this quantity of SSNM is sometimes referred
to as a Category I quantity of material.
-
High-Enriched Uranium (HEU): Any uranium-bearing material whose
uranium isotope content is 20 percent or more U-235 by weight (relative
to total uranium element content).
Inventory Difference (ID): The arithmetic difference between
a book inventory and the corresponding physical inventory, calculated
by subtracting ending inventory (EI) from the combination of beginning
inventory (BI) plus additions to inventory (A) minus removals from
inventory (R). Mathematically, this can be expressed as:
ID = (BI + A - R) - EI or ID = BI + A - R - EI
Isotope: A nuclide of a chemical element (such as uranium
or plutonium) whose atoms all have the same number of protons characteristic
of that element combined with different numbers of neutrons. That is,
all isotopes of a given element must have the same number of protons
within the nuclei of their atoms, but the number of neutrons per nucleus
varies between isotopes. It is the number of protons plus neutrons
within an atom's nucleus that defines its mass number. For example,
U-235 and U-238 are two isotopes of uranium. Both contain 92 protons
but have 143 and 146 neutrons, respectively, within the nucleus of
each of their atoms.
Low-Enriched Uranium (LEU): Any uranium-bearing material
whose uranium isotope content is less than 20 percent, but greater
than 0.71 percent, U-235 by weight (relative to total uranium element
content).
Natural Uranium: Any uranium-bearing material whose uranium
isotopic distribution has not been altered from its naturally occurring
state. Natural uranium is nominally 99.283 percent U-238, 0.711 percent
U-235, and 0.006 percent U-234.
Negative ID: A situation that occurs when the amount of SNM
on hand, as determined by the physical inventory, exceeds the amount
of SNM being carried on the books (records). That is, there appears
to be a gain in material. Mathematically, a negative ID is written
as "-ID," or shown in parentheses. A negative ID is also referred to
as an "ID
gain."
Plant: For SNM control and accounting purposes, a plant is
defined as a set of processes or operations (on the same site, but
not necessarily all in the same building) coordinated into a single
manufacturing, R&D, or testing effort. Most licensees have
only one plant in this context. A scrap recovery operation serving both
onsite and offsite customers, or more than one onsite manufacturing
effort (plant), would be treated as a separate plant.
Positive ID: A situation that occurs when the amount of SNM
on hand, as determined by the physical inventory, is less than the
amount of SNM being carried on the books (records). That is, there
appears to be a loss of material. Mathematically, a positive ID is
written as "+ID," or is shown without any designation of a sign. A
positive ID is also referred to as an "ID loss."
Source Material (SM): (1) Natural uranium or thorium, or
depleted uranium, or any combination thereof, in any physical or chemical
form, or (2) ores that contain by weight 0.05 percent or more of (i)
uranium, (ii) thorium, or (iii) any combination thereof. SM does not
include SNM.
Special Nuclear Material (SNM): (1) Plutonium, uranium-233,
uranium enriched in the isotope uranium-235, and any other material
that the U.S. Government, pursuant to the provisions of Section 51
of the Atomic Energy Act of 1954, as amended, determines to be SNM;
or (2) any material artificially enriched in any of the foregoing.
SNM (of any type) does not include SM.
SNM Material Type Categories: For inventory and accounting
purposes, SNM is classified into six material type categories (not
to be confused with Categories I, II, and III quantities). The six
categories are uranium in cascades, LEU, HEU, uranium-233, plutonium,
and plutonium-238. For each category, SNM is accounted for on both
a total element and isotope basis. The element and isotope for each
category are as follows:
CATEGORY |
ELEMENT |
ISOTOPE |
|
|
|
Uranium in Cascades |
Total Uranium |
U-235 |
LEU |
Total Uranium |
U-235 |
HEU |
Total Uranium |
U-235 |
Uranium-233 |
Total Uranium |
U-233 |
Plutonium |
Total Plutonium |
Pu-239 + Pu-241 |
Plutonium-238 |
Total Plutonium |
Pu-238 |
- SNM of Low Strategic Significance: (1) Less than an amount of SNM of moderate
strategic significance, but more than 15 grams of (i) U-235 contained in HEU, (ii) U-233,
(iii) plutonium, or (iv) any combination thereof; (2) less than 10,000 grams, but more
than 1,000 grams of U-235 contained in LEU enriched to 10 percent or more (but less
than 20 percent) in the U-235 isotope; or (3) 10,000 grams or more of U-235 contained
in LEU enriched above natural, but less than 10 percent, in the U-235 isotope.
NOTE: In unirradiated form, any of the above three quantities are sometimes referred
to as a Category III quantity.
SNM of Moderate Strategic Significance: (1) Less than a formula quantity of SSNM, but
more than 1,000 grams of U-235 contained in HEU, or more than 500 grams of U-233 or
plutonium, or more than a combined quantity of 1,000 formula grams when computed by
the equation:
Formula Grams = (grams U-235 in HEU) + 2.0 (grams U-233
+ grams Pu)
or (2) 10,000 grams or more of U-235 contained in LEU enriched to 10 percent or more
(but less than 20 percent) in the U-235 isotope.
NOTE: In unirradiated form, either of the aforementioned two quantities is sometimes
referred to as a Category II quantity.
Standard Error of the ID (SEID):
(a) |
|
For Category III licensees subject to 10 CFR 74.31 or 74.33, SEID is equal to the
square root of the sum of both measurement and non-measurement variances
associated with an ID. |
|
|
|
(b) |
|
For Category I and II licensees subject to 10 CFR 74.59 and 74.43, respectively,
SEID is equal to the square root of the measurement variance (only) associated
with an ID. |
- Strategic Special Nuclear Material (SSNM): Uranium-235 contained in HEU, uranium-
233, or plutonium.
NOTE: All SSNM is SNM, but not all SNM is SSNM.
- The ID Exceeded Its Regulatory Limit: The ID exceeded its applicable regulatory limit
and was thus subject to both licensee and NRC investigations to determine the cause(s)
of the excessive value (regardless of whether the ID was negative or positive).
- The ID Was Within Its Expected Range: The ID was less than (i) 200 grams plutonium
or U-233, (ii) 300 grams U-235 contained in HEU, or (iii) 9,000 grams U-235 contained
in LEU, as appropriate.
- The ID Was Within Its Regulatory Limit: The ID exceeded both (1) 200 grams U-233 or
plutonium, 300 grams U-235 contained in HEU, or 9,000 grams U-235 contained in LEU
(as appropriate), and (2) its associated SEID, but was less than the ID limit. For 10 CFR
74.31and 74.33 licensees, the ID limit is the site-specific detection threshold quantity,
which is considerably larger than SEID. For 10 CFR 74.43 and 74.59 licensees, the ID
limit is 3 times SEID.
5. TABULATION OF INVENTORY DIFFERENCES
Licensee |
|
SNM
License No. |
Docket
No. |
|
SNM
Category |
|
Inventory
Date |
|
Inventory
Difference (Grams U-235) |
|
Explanation
[See definitions #25, 26, & 27] |
|
|
|
|
|
|
|
|
|
|
|
|
BWX Technologies, Inc.
(formerly Babcock & Wilcox) Nuclear Products Division |
|
42
|
70-27
|
|
HEU
|
|
10/31/01 |
|
+ 854
|
|
The ID was within its regulatory limit.
|
Lynchburg, Virginia
|
|
|
|
|
HEU
|
|
03/31/02 |
|
+ 206
|
|
The ID was within its regulatory limit.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
LEU
|
|
03/31/02 |
|
+ 1,339
|
|
The ID was within its
regulatory limit
|
|
|
|
|
|
|
|
|
|
|
|
|
Nuclear Fuel Services Erwin, Tennessee
|
|
124 |
70-143
|
|
HEU
|
|
08/09/01 |
|
+ 5
|
|
The ID was within its
expected range.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
HEU
|
|
02/01/02 |
|
+ 2,664 |
|
The ID exceeded its regulatory
limit of 3 times SEID. The ID loss
resulted from measurement
biases. No enforcement or
regulatory action was required.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
HEU
|
|
05/17/02 |
|
+ 2,664 |
|
The ID exceeded its regulatory
limit of 3 times SEID. The ID loss
resulted from measurement
biases. No enforcement or
regulatory action was required. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
LEU
|
|
06/26/02 |
|
- 38,460 |
|
The ID exceeded its regulatory
limit. The ID gain resulted from
decommissioning activities. No
regulatory action was required. |
|
|
|
|
|
|
|
|
|
|
|
|
Framatome ANP (formerly Framatome-Cogema Fuels)
Lynchburg, Virginia
|
|
1168 |
70-1201
|
|
LEU
|
|
02/28/01
|
|
- 2,603 |
|
The ID was within its expected range.
|
|
|
|
|
|
|
|
|
|
|
|
|
Framatome ANP (formerly Siemens Nuclear Power
Corp.) Richland, Washington
|
|
1227 |
70-1257
|
|
LEU
|
|
04/08/01
|
|
+ 21,074 |
|
The ID was within its regulatory limit. |
|
|
|
|
|
|
|
|
|
|
|
|
Global Nuclear Fuel, Americas (formerly General
Electric Company) Wilmington, North Carolina
|
|
1097 |
70-1113
|
|
LEU
|
|
08/02/00
|
|
- 4,225 |
|
The ID was within its regulatory limit.
|
|
|
|
|
|
|
|
|
|
|
|
|
U. S. Enrichment Corp. Paducah Gaseous Diffusion Plant
Paducah, Kentucky |
|
GDP-1 |
70-7001
|
|
LEU
|
|
10/03/00
|
|
+ 79,979 |
|
The ID was within its regulatory limit.
|
|
|
|
|
|
|
|
|
|
|
|
|
U. S. Enrichment Corp. Portsmouth Gaseous Diffusion Plant
Piketon, Ohio |
|
GDP-2 |
70-7002
|
|
HEU
|
|
09/30/01 |
|
+ 31 |
|
The ID was within its expected range.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
LEU
|
|
09/30/01 |
|
- 83,671 |
|
The ID was within its
regulatory limit.
|
|
|
|
|
|
|
|
|
|
|
|
|
Westinghouse Electric Corp. Columbia, South Carolina
|
|
1107 |
70-1151
|
|
LEU
|
|
04/27/02 |
|
+ 2,015 |
|
The ID was within its regulatory limit.
|
|
|
|
|
|
|
|
|
|
|
|
|
Westinghouse Electric Corp. 33 (formerly Combustion
Engineering) Hematite, Missouri
|
|
|
70-36
|
|
LEU
|
|
06/30/02 |
|
- 73,603 |
|
The ID was within its regulatory limit.
|
|