[Federal Register Volume 71, Number 98 (Monday, May 22, 2006)]
[Notices]
[Pages 29364-29368]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-4750]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos: (Redacted), License Nos: (Redacted), EA-05-090]


In the Matter of All Licensees Authorized To Possess Radioactive 
Material Quantities of Concern, Order Imposing Increased Controls 
(Effective Immediately).

    The Licensees identified in Attachment A \1\ to this Order hold 
licenses issued in accordance with the Atomic Energy Act of 1954 by the 
U.S. Nuclear Regulatory Commission (NRC or Commission) and authorizing 
them to possess certain quantities of radioactive material of concern. 
Commission

[[Page 29365]]

regulations at 10 CFR 20.1801 require Licensees to secure, from 
unauthorized removal or access, licensed materials that are stored in 
controlled or unrestricted areas. Commission regulations at 10 CFR 
20.1802 require Licensees to control and maintain constant surveillance 
of licensed material that is in a controlled or unrestricted area and 
that is not in storage.
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    \1\ Attachment A contains sensitive information and will not be 
released to the public.
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    Prior to the terrorist attacks of September 11, 2001 (9/11), 
several national and international efforts were underway to address the 
potentially significant health and safety hazards posed by uncontrolled 
sources. These efforts recognized the need for increased control of 
high-risk radioactive materials to prevent inadvertent and intentional 
unauthorized access, primarily due to the potential health and safety 
hazards posed by the uncontrolled material. Following 9/11, it was 
recognized that these efforts should also include a heightened 
awareness and focus on the need to prevent intentional unauthorized 
access due to potential malicious acts. These efforts, such as the 
International Atomic Energy Agency (IAEA) Code of Conduct on the Safety 
and Security of Radioactive Sources (Code of Conduct) concerning 
Category 1 and 2 sources, seek to increase the control over sources to 
prevent unintended radiation exposure and to prevent malicious acts.
    A licensee's loss of control of high-risk radioactive sources, 
whether it be inadvertent or through a deliberate act, has a potential 
to result in significant adverse health impacts and could reasonably 
constitute a threat to the public health and safety. In this regard, 
the Commission has determined that certain additional controls are 
required to be implemented by Licensees to supplement existing 
regulatory requirements in 10 CFR 20.1801 and 10 CFR 20.1802, in order 
to ensure adequate protection of, and minimize danger to, the public 
health and safety. Therefore, the Commission is imposing the 
requirements set forth in Attachment B on radioactive materials 
licensees who possess, or have near term plans to possess, 
radionuclides of concern at or above threshold limits, identified in 
Table 1. These requirements, which supplement existing regulatory 
requirements, will provide the Commission with reasonable assurance 
that the public health and safety continues to be adequately protected. 
These requirements will remain in effect until the Commission modifies 
its regulations to reflect increased controls.
    To effect nationwide implementation, these measures have been 
determined by the Commission to be an immediate mandatory Category 
``B'' matter of compatibility for Agreement States. In parallel with 
the Commission's issuance of this Order, each Agreement State is 
required to issue legally binding requirements to put essentially 
identical measures in place for licensees under their regulatory 
jurisdiction.
    The Commission recognizes that Licensees may have already initiated 
many controls set forth in Attachment B to this Order in response to 
previously issued advisories or on their own. It is also recognized 
that some controls may not be possible or necessary at some sites, or 
may need to be tailored to accommodate the Licensees' specific 
circumstances to achieve the intended objectives and avoid any 
unforeseen adverse effect on the safe use and storage of the sealed 
sources.
    Although the additional controls implemented by the Licensees in 
response to the Safeguards and Threat Advisories have been adequate to 
provide reasonable assurance of adequate protection of public health 
and safety, the Commission concludes that additional controls must be 
imposed by an Order, consistent with the established regulatory 
framework.
    To provide assurance that the Licensees are implementing prudent 
measures to achieve a consistent level of control, all Licensees who 
hold licenses issued by the NRC authorizing possession of radioactive 
material quantities of concern and as listed in Table 1, 
``Radionuclides of Concern,'' (Attachment B, Table 1), shall implement 
the requirements identified in Attachment B to this Order. In addition, 
pursuant to 10 CFR 2.202, because of the potentially significant 
adverse health impacts associated with failure to control high risk 
radioactive sources, I find that the public health, safety, and 
interest require that this Order be effective immediately.
    Accordingly, pursuant to Sections 81, 161b, 161i, 161o, 182 and 186 
of the Atomic Energy Act of 1954, as amended, and the Commission's 
regulations in 10 CFR 2.202, 10 CFR part 30, and 10 CFR part 33, it is 
hereby ordered, effective immediately, that all licensees identified in 
Attachment A to this Order shall comply with the requirements of this 
Order as Follows:
    A. The Licensee shall comply with the requirements described in 
Attachment B to this Order. The Licensee shall complete implementation 
by June 2, 2006, or the first day that radionuclides of concern at or 
above threshold limits, identified in Table 1, are possessed, whichever 
occurs later.
    B. 1. The Licensee shall in writing, within twenty five (25) days 
of the date of this Order, notify the Commission, (1) if it is unable 
to comply with any of the requirements described in Attachment B, (2) 
if compliance with any of the requirements is unnecessary in its 
specific circumstances, or (3) if implementation of any of the 
requirements would cause the Licensee to be in violation of the 
provisions of any Commission regulation or its license. The 
notification shall provide the Licensee's justification for seeking 
relief from or variation of any specific requirement.
    B. 2. If the Licensee considers that implementation of any of the 
requirements described in Attachment B to this Order would adversely 
impact safe operation of the facility, the Licensee must notify the 
Commission, in writing, within twenty five (25) days of this Order, of 
the adverse safety impact, the basis for its determination that the 
requirement has an adverse safety impact, and either a proposal for 
achieving the same objectives specified in the Attachment B requirement 
in question, or a schedule for modifying the facility to address the 
adverse safety condition. If neither approach is appropriate, the 
Licensee must supplement its response to Condition B.1 of this Order to 
identify the condition as a requirement with which it cannot comply, 
with attendant justifications as required in Condition B.1.
    C. 1. The Licensee shall, within twenty five (25) days of the date 
of this Order, submit to the Commission a schedule for completion of 
each requirement described in Attachment B.
    C. 2. The Licensee shall report to the Commission when they have 
achieved full compliance with the requirements described in Attachment 
B.
    D. Notwithstanding any provisions of the Commission's regulations 
to the contrary, all measures implemented or actions taken in response 
to this Order shall be maintained until the Commission modifies its 
regulations to reflect increased controls.
    Licensee responses to Conditions B.1, B.2, C.1, and C.2 above shall 
be submitted to the Director, Office of Nuclear Material Safety and 
Safeguards, U.S. Nuclear Regulatory Commission, Washington, DC 20555. 
In addition, Licensee's responses shall be marked as ``Withhold From 
Public disclosure Under 10 CFR 2.390.''
    The Director, Office of Nuclear Material Safety and Safeguards, 
may, in writing, relax or rescind any of the

[[Page 29366]]

above conditions upon demonstration by the Licensee of good cause.
    In accordance with 10 CFR 2.202, the Licensee must, and any other 
person adversely affected by this Order may, submit an answer to this 
Order, and may request a hearing on this Order, within twenty five (25) 
days of the date of this Order. Where good cause is shown, 
consideration will be given to extending the time to request a hearing. 
A request for extension of time in which to submit an answer or request 
a hearing must be made in writing to the Director, Office of Nuclear 
Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, 
Washington, DC 20555, and include a statement of good cause for the 
extension. The answer may consent to this Order. Unless the answer 
consents to this Order, the answer shall, in writing and under oath or 
affirmation, specifically set forth the matters of fact and law on 
which the Licensee or other person adversely affected relies and the 
reasons as to why the Order should not have been issued. Any answer or 
request for a hearing shall be submitted to the Secretary, Office of 
the Secretary of the Commission, U.S. Nuclear Regulatory Commission, 
ATTN: Rulemakings and Adjudications Staff, Washington, DC 20555. Copies 
also shall be sent to the Director, Office of Nuclear Material Safety 
and Safeguards, U.S. Nuclear Regulatory Commission, Washington, DC 
20555, to the Assistant General Counsel for Materials Litigation and 
Enforcement at the same address, and to the Licensee if the answer or 
hearing request is by a person other than the Licensee. Because of 
possible disruptions in delivery of mail to United States Government 
offices, it is requested that answers and requests for hearing be 
transmitted to the Secretary of the Commission either by means of 
facsimile transmission to 301-415-1101 or by e-mail to 
[email protected] and also to the Office of the General Counsel 
either by means of facsimile transmission to 301-415-3725 or by e-mail 
to [email protected]. If a person other than the Licensee requests 
a hearing, that person shall set forth with particularity the manner in 
which his interest is adversely affected by this Order and shall 
address the criteria set forth in 10 CFR 2.309(d) and (f).
    If a hearing is requested by the Licensee or a person whose 
interest is adversely affected, the Commission will issue an Order 
designating the time and place of any hearing. If a hearing is held, 
the issue to be considered at such hearing shall be whether this Order 
should be sustained.
    Pursuant to 10 CFR 2.202(c)(2)(I), the Licensee may, in addition to 
demanding a hearing, at the time the answer is filed or sooner, move 
the presiding officer to set aside the immediate effectiveness of the 
Order on the ground that the Order, including the need for immediate 
effectiveness, is not based on adequate evidence but on mere suspicion, 
unfounded allegations, or error.
    In the absence of any request for hearing, or written approval of 
an extension of time in which to request a hearing, the provisions 
specified in Section III above shall be final twenty five (25) days 
from the date of this Order without further order or proceedings. If an 
extension of time for requesting a hearing has been approved, the 
provisions specified in Section III shall be final when the extension 
expires if a hearing request has not been received. An answer or a 
request for hearing shall not stay the immediate effectiveness of this 
Order.
    Although this Order is not subject to the requirements of the 
Paperwork Reduction Act, there is nonetheless a clearance from the 
Office of Management and Budget, OMB approval number 3150-0002, that 
covers the information collections contained in the Order.

    Dated this 9th day of May 2006.
    For the Nuclear Regulatory Commission.
Jack R. Strosnider,
Director, Office of Nuclear Material Safety and Safeguards.

Attachment A--Redacted

Attachment B--Increased Controls for Licensees That Possess Sources 
Containing Radioactive Material Quantities of Concern

    The purpose of the increased controls (IC) for radioactive sources 
is to enhance control of radioactive material in quantities greater 
than or equal to values described in Table 1, to reduce the risk of 
unauthorized use of radioactive materials, through access controls to 
aid prevention, and prompt detection, assessment, and response to 
mitigate potentially high consequences that would be detrimental to 
public health and safety. These increased controls for radioactive 
sources are established to delineate licensee responsibility to 
maintain control of licensed material and secure it from unauthorized 
removal or access. The following increased controls apply to licensees 
which, at any given time, possess radioactive sources greater than or 
equal to the quantities of concern of radioactive material defined in 
Table 1.
    IC 1. In order to ensure the safe handling, use, and control of 
licensed material in use and in storage each licensee shall control 
access at all times to radioactive material quantities of concern and 
devices containing such radioactive material (devices), and limit 
access to such radioactive material and devices to only approved 
individuals who require access to perform their duties.
    a. The licensee shall allow only trustworthy and reliable 
individuals, approved in writing by the licensee, to have unescorted 
access to radioactive material quantities of concern and devices. The 
licensee shall approve for unescorted access only those individuals 
with job duties that require access to such radioactive material and 
devices. Personnel who require access to such radioactive material and 
devices to perform a job duty, but who are not approved by the licensee 
for unescorted access, must be escorted by an approved individual.
    b. For individuals employed by the licensee for 3 years or less, 
and for non-licensee personnel, such as physicians, physicists, house-
keeping personnel, and security personnel under contract, 
trustworthiness and reliability shall be determined, at a minimum, by 
verifying employment history, education, and personal references. The 
licensee shall also, to the extent possible, obtain independent 
information to corroborate that provided by the employee (i.e., seeking 
references not supplied by the individual). For individuals employed by 
the licensee for longer than 3 years, trustworthiness and reliability 
shall be determined, at a minimum, by a review of the employees' 
employment history with the licensee.
    c. Service providers shall be escorted unless determined to be 
trustworthy and reliable by an NRC-required background investigation as 
an employee of a manufacturing and distribution (M&D) licensee. Written 
verification attesting to or certifying the person's trustworthiness 
and reliability shall be obtained from the manufacturing and 
distribution licensee providing the service.
    d. The licensee shall document the basis for concluding that there 
is reasonable assurance that an individual granted unescorted access is 
trustworthy and reliable, and does not constitute an unreasonable risk 
for unauthorized use of radioactive material quantities of concern. The 
licensee shall maintain a list of persons approved for unescorted 
access to such radioactive material and devices by the licensee.
    IC 2. In order to ensure the safe handling, use, and control of 
licensed material in use and in storage, each licensee shall have a 
documented

[[Page 29367]]

program to monitor and immediately detect, assess, and respond to 
unauthorized access to radioactive material quantities of concern and 
devices. Enhanced monitoring shall be provided during periods of source 
delivery or shipment, where the delivery or shipment exceeds 100 times 
the Table 1 values.
    a. The licensee shall respond immediately to any actual or 
attempted theft, sabotage, or diversion of such radioactive material or 
of the devices. The response shall include requesting assistance from a 
Local Law Enforcement Agency (LLEA).
    b. The licensee shall have a pre-arranged plan with LLEA for 
assistance in response to an actual or attempted theft, sabotage, or 
diversion of such radioactive material or of the devices which is 
consistent in scope and timing with a realistic potential vulnerability 
of the sources containing such radioactive material. The pre-arranged 
plan shall be updated when changes to the facility design or operation 
affect the potential vulnerability of the sources. Pre-arranged LLEA 
coordination is not required for temporary job sites.
    c. The licensee shall have a dependable means to transmit 
information between, and among, the various components used to detect 
and identify an unauthorized intrusion, to inform the assessor, and to 
summon the appropriate responder.
    d. After initiating appropriate response to any actual or attempted 
theft, sabotage, or diversion of radioactive material or of the 
devices, the licensee shall, as promptly as possible, notify NRC 
Operations Center at (301) 816-5100.
    e. The licensee shall maintain documentation describing each 
instance of unauthorized access and any necessary corrective actions to 
prevent future instances of unauthorized access.
    IC 3. a. In order to ensure the safe handling, use, and control of 
licensed material in transportation for domestic highway and rail 
shipments by a carrier other than the licensee, for quantities that 
equal or exceed those in Table 1 but are less than 100 times Table 1 
quantities, per consignment, the licensee shall:
    1. Use carriers which:
    A. Use package tracking systems,
    B. Implement methods to assure trustworthiness and reliability of 
drivers,
    C. Maintain constant control and/or surveillance during transit, 
and
    D. Have the capability for immediate communication to summon 
appropriate response or assistance.
    The licensee shall verify and document that the carrier employs the 
measures listed above.
    2. Contact the recipient to coordinate the expected arrival time of 
the shipment;
    3. Confirm receipt of the shipment; and
    4. Initiate an investigation to determine the location of the 
licensed material if the shipment does not arrive on or about the 
expected arrival time. When, through the course of the investigation, 
it is determined the shipment has become lost, stolen, or missing, the 
licensee shall immediately notify the NRC Operations Center at (301) 
816-5100. If, after 24 hours of investigating, the location of the 
material still cannot be determined, the radioactive material shall be 
deemed missing and the licensee shall immediately notify the NRC 
Operations Center at (301) 816-5100.
    b. For domestic highway and rail shipments, prior to shipping 
licensed radioactive material that exceeds 100 times the quantities in 
Table 1 per consignment, the licensee shall:
    1. Notify the NRC\1\, in writing, at least 90 days prior to the 
anticipated date of shipment. The NRC will issue the Order to implement 
the Additional Security Measures (ASMs) for the transportation of 
Radioactive Material Quantities of Concern (RAM QC). The licensee shall 
not ship this material until the ASMs for the transportation of RAM QC 
are implemented or the licensee is notified otherwise, in writing, by 
NRC.
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    \1\ Director, Office of Nuclear Material Safety and Safeguards, 
U.S. Nuclear Regulatory Commission, Washington, DC 20555.
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    2. Once the licensee has implemented the ASMs for the 
transportation of RAM QC, the notification requirements of 3.b.1 shall 
not apply to future shipments of licensed radioactive material that 
exceeds 100 times the Table 1 quantities. The licensee shall implement 
the ASMs for the transportation of RAM QC.
    c. If a licensee employs an M&D licensee to take possession at the 
licensee's location of the licensed radioactive material and ship it 
under its M&D license, the requirements of 3.a. and 3.b above shall not 
apply.
    d. If the licensee is to receive radioactive material greater than 
or equal to the Table 1 quantities, per consignment, the licensee shall 
coordinate with the originator to:
    1. Establish an expected time of delivery; and
    2. Confirm receipt of transferred radioactive material. If the 
material is not received at the expected time of delivery, notify the 
originator and assist in any investigation.
    IC 4. In order to ensure the safe handling, use, and control of 
licensed material in use and in storage each licensee that possesses 
mobile or portable devices containing radioactive material in 
quantities greater than or equal to Table 1 values, shall:
    a. For portable devices, have two independent physical controls 
that form tangible barriers to secure the material from unauthorized 
removal when the device is not under direct control and constant 
surveillance by the licensee.
    b. For mobile devices:
    1. that are only moved outside of the facility (e.g., on a 
trailer), have two independent physical controls that form tangible 
barriers to secure the material from unauthorized removal when the 
device is not under direct control and constant surveillance by the 
licensee.
    2. that are only moved inside a facility, have a physical control 
that forms a tangible barrier to secure the material from unauthorized 
movement or removal when the device is not under direct control and 
constant surveillance by the licensee.
    c. For devices in or on a vehicle or trailer, licensees shall also 
utilize a method to disable the vehicle or trailer when not under 
direct control and constant surveillance by the licensee
    IC 5.The licensee shall retain documentation required by these 
increased controls for 3 years after they are no longer effective:
    a. The licensee shall retain documentation regarding the 
trustworthiness and reliability of individual employees for 3 years 
after the individual's employment ends.
    b. Each time the licensee revises the list of approved persons 
required by 1.d., or the documented program required by 2, the licensee 
shall retain the previous documentation for 3 years after the revision.
    c. The licensee shall retain documentation on each radioactive 
material carrier for 3 years after the licensee discontinues use of 
that particular carrier.
    d. The licensee shall retain documentation on shipment 
coordination, notifications, and investigations for 3 years after the 
shipment or investigation is completed.
    e. After the license is terminated or amended to reduce possession 
limits below the quantities of concern, the licensee shall retain all 
documentation required by these increased controls for 3 years.
    IC 6.Detailed information generated by the licensee that describes 
the physical protection of radioactive

[[Page 29368]]

material quantities of concern, is sensitive information and shall be 
protected from unauthorized disclosure.
    a. The licensee shall control access to its physical protection 
information to those persons who have an established need to know the 
information, and are considered to be trustworthy and reliable.
    b. The licensee shall develop, maintain and implement policies and 
procedures for controlling access to, and for proper handling and 
protection against unauthorized disclosure of, its physical protection 
information for radioactive material covered by these requirements. The 
policies and procedures shall include the following:
    1. General performance requirement that each person who produces, 
receives, or acquires the licensee's sensitive information, protect the 
information from unauthorized disclosure,
    2. Protection of sensitive information during use, storage, and 
transit,
    3. Preparation, identification or marking, and transmission,
    4. Access controls,
    5. Destruction of documents,
    6. Use of automatic data processing systems, and
    7. Removal from the licensee's sensitive information category.

                   Table 1.--Radionuclides of Concern
------------------------------------------------------------------------
                                                               Quantity
             Radionuclide              Quantity of concern 1  of concern
                                                (TBq)          2  (Ci )
------------------------------------------------------------------------
Am-241...............................  0.6..................          16
Am-241/Be............................  0.6..................          16
Cf-252...............................  0.2..................         5.4
Cm-244...............................  0.5..................          14
Co-60................................  0.3..................         8.1
Cs-137...............................  1....................          27
Gd-153...............................  10...................         270
Ir-192...............................  0.8..................          22
Pm-147...............................  400..................      11,000
Pu-238...............................  0.6..................          16
Pu-239/Be............................  0.6..................          16
Se-75................................  2....................          54
Sr-90 (Y-90).........................  10...................         270
Tm-170...............................  200..................       5,400
Yb-169...............................  3....................          81
Combinations of radioactive materials  See Footnote Below 4.
 listed above 3.
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1 The aggregate activity of multiple, collocated sources of the same
  radionuclide should be included when the total activity equals or
  exceeds the quantity of concern.
2 The primary values used for compliance with this Order are TBq. The
  curie (Ci) values are rounded to two significant figures for
  informational purposes only.
3 Radioactive materials are to be considered aggregated or collocated if
  breaching a common physical security barrier (e.g., a locked door at
  the entrance to a storage room) would allow access to the radioactive
  material or devices containing the radioactive material.
4 If several radionuclides are aggregated, the sum of the ratios of the
  activity of each source, I of radionuclide, n, A(i,n), to the quantity
  of concern for radionuclide n, Q(n), listed for that radionuclide
  equals or exceeds one. [(aggregated source activity for radionuclide
  A) (quantity of concern for radionuclide A)] + [(aggregated source
  activity for radionuclide B) (quantity of concern for radionuclide B)]
  + etc........ >1.

    Use the following method to determine which sources of radioactive 
material require increased controls (ICs):
     Include any single source equal to or greater than the 
quantity of concern in Table 1
     Include multiple collocated sources of the same 
radionuclide when the combined quantity equals or exceeds the quantity 
of concern
     For combinations of radionuclides, include multiple 
collocated sources of different radionuclides when the aggregate 
quantities satisfy the following unity rule: [(amount of radionuclide 
A)/ (quantity of concern of radionuclide A)] + [(amount of radionuclide 
B)/ (quantity of concern of radionuclide B)] + etc..... >=1.

Guidance for Aggregation of Sources

    NRC supports the use of the IAEA's source categorization 
methodology as defined in TECDOC-1344, ``Categorization of Radioactive 
Sources,'' (July 2003) (see http://www-pub.iaea.org/MTCD/publications/PDF/te_1344_web.pdf) and as endorsed by the agency's Code of Conduct 
for the Safety and Security of Radioactive Sources, January 2004 (see 
http://www-pub.iaea.org/MTCD/publications/PDF/Code-2004_web.pdf ). The 
Code defines a three-tiered source categorization scheme. Category 1 
corresponds to the largest source strength (equal to or greater than 
100 times the quantity of concern values listed in Table 1.) and 
Category 3, the smallest (equal or exceeding one-tenth the quantity of 
concern values listed in Table 1.). Increased controls apply to sources 
that are equal to or greater than the quantity of concern values listed 
in Table 1, plus aggregations of smaller sources that are equal to or 
greater than the quantities in Table 1. Aggregation only applies to 
sources that are collocated.
    Licensees who possess individual sources in total quantities that 
equal or exceed the Table 1 quantities are required to implement 
increased controls. Where there are many small (less than the quantity 
of concern values) collocated sources whose total aggregate activity 
equals or exceeds the Table 1 values, licensees are to implement 
increased controls.
    Some source handling or storage activities may cover several 
buildings, or several locations within specific buildings. The question 
then becomes: When are sources considered collocated for purposes of 
aggregation? For purposes of the additional controls, sources are 
considered collocated if breaching a single barrier (e.g., a locked 
door at the entrance to a storage room) would allow access to the 
sources. Sources behind an outer barrier should be aggregated 
separately from those behind an inner barrier (e.g., a locked source 
safe inside the locked storage room). However, if both barriers are 
simultaneously open, then all sources within these two barriers are 
considered to be collocated. This logic should be continued for other 
barriers within or behind the inner barrier.
    The following example illustrates the point: A lockable room has 
sources stored in it. Inside the lockable room, there are two shielded 
safes with additional sources in them. Inventories are as follows:
    The room has the following sources outside the safes: Cf-252, 0.12 
TBq (3.2 Ci); Co-60, 0.18 TBq (4.9 Ci), and Pu-238, 0.3 TBq (8.1 Ci). 
Application of the unity rule yields: (0.12 / 0.2) + (0.18 / 0.3) + 
(0.3 0.6) = 0.6 + 0.6 + 0.5 = 1.7. Therefore, the sources would require 
increased controls.
    Shielded safe 1 has a 1.9 TBq (51 Ci) Cs-137 source and a 
0.8 TBq (22 Ci) Am-241 source. In this case, the sources would require 
increased controls, regardless of location, because they each exceed 
the quantities in Table 1.
    Shielded safe 2 has two Ir-192 sources, each having an 
activity of 0.3 TBq (8.1 Ci). In this case, the sources would not 
require increased controls while locked in the safe. The combined 
activity does not exceed the threshold quantity 0.8 TBq (22 Ci).
    Because certain barriers may cease to exist during source handling 
operations (e.g., a storage location may be unlocked during periods of 
active source usage), licensees should, to the extent practicable, 
consider two modes of source usage--``operations'' (active source 
usage) and ``shutdown'' (source storage mode). Whichever mode results 
in the greatest inventory (considering barrier status) would require 
increased controls for each location.

[FR Doc. 06-4750 Filed 5-19-06; 8:45 am]
BILLING CODE 7590-01-P