United States Nuclear Regulatory Commission - Protecting People and the Environment

Thermo-Lag 330-1 Fire Barriers (Generic Letter 92-08)


                                  December 17, 1992



TO:         ALL HOLDERS OF OPERATING LICENSES OR CONSTRUCTION PERMITS FOR
            NUCLEAR POWER REACTORS

SUBJECT:    THERMO-LAG 330-1 FIRE BARRIERS (GENERIC LETTER 92-08)

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this generic letter
(GL) to obtain additional information needed from licensees to verify that
Thermo-Lag 330-1 fire barrier systems manufactured by Thermal Science,
Incorporated (TSI, the vendor), St. Louis, Missouri, comply with the NRC's
requirements.  Many licensees use Thermo-Lag 330-1 fire barriers to satisfy
the NRC's fire protection requirements for safe shutdown capability.  Some
licensees also use Thermo-Lag 330-1 barriers to create physical independence
between the circuits and electric equipment in and associated with the
Class 1E power system, the protection system, systems actuated or controlled
by the protection system, and auxiliary or supporting systems that must be
operable for the protection system and the systems it actuates to perform
their safety-related functions.

BACKGROUND

The NRC began a review of Thermo-Lag 330-1 fire barrier system fire endurance
and ampacity derating test reports, installation procedures, and as-built
configurations after receiving reports from Gulf States Utilities (GSU) about
failed qualification fire tests and installation problems.  The staff issued
the results of the NRC's initial review in NRC Information Notice (IN) 92-46,
"Thermo-Lag Fire Barrier Material Special Review Team Findings, Current Fire
Endurance Tests, and Ampacity Calculation Errors," June 23, 1992.  The special
review team report enclosed with IN 92-46 included the technical bases for
this generic letter.  The NRC staff found the following regarding
Thermo-Lag 330-1 barriers:  incomplete or indeterminate fire test results,
questionable ampacity derating test results and a wide range of documented
ampacity derating factors, some barrier installations that are not constructed
in accordance with the vendor recommended installation procedures, incomplete
installation procedures, and as-built fire barrier configurations that may not
be qualified by a valid fire endurance test or evaluated in accordance with
the guidance previously provided by the staff in GL 86-10, "Implementation of
Fire Protection Requirements," April 24, 1986.  

Texas Utilities Electric Company (TU Electric) later conducted a series of
full-scale fire endurance tests to qualify the Thermo-Lag 330-1 electrical
raceway fire barrier configurations installed at its Comanche Peak Steam
Electric Station.  The NRC also conducted a series of small-scale fire tests
of 1-hour and 3-hour Thermo-Lag prefabricated panels at the National Institute
of Standards and Technology to assess the fire performance of the panels.  The
results of these fire tests raised additional concerns about the ability of


9212140065.

GENERIC LETTER 92-08                 -2-              December 17, 1992


Thermo-Lag 330-1 fire barriers to provide fire protection according to their
specified fire-resistance ratings.  

The staff issued the results of the TU Electric and NRC fire tests in
Bulletins 92-01, "Failure of Thermo-Lag 330 Fire Barrier System to Maintain
Cabling in Wide Cable Trays and Small Conduits Free from Fire Damage,"
June 24, 1992, and 92-01, Supplement 1, "Failure of Thermo-Lag 330-1 Fire
Barrier System to Perform its Specified Fire Endurance Function,"
August 28, 1992.  In the bulletin and its supplement, the NRC notified the
licensees of apparent failures of Thermo-Lag 330-1 fire barriers and materials
during fire endurance testing.  The bulletin and its supplement requested that
each licensee determine which plant areas use 1-hour or 3-hour prefabricated
Thermo-Lag 330-1 panels or conduit shapes for raceway, wall, ceiling, or
equipment enclosure fire barriers; determine the plant areas that use these
materials to protect or separate safe shutdown capability; and implement, in
accordance with plant procedures, compensatory measures until the fire
barriers can be declared operable.  The bulletin required that each licensee
inform the NRC in writing whether or not the above requested actions were
taken and describe the measures being taken to ensure or restore fire barrier
operability.  

AREAS OF CONCERN

The NRC has three principal areas of concern:  the fire endurance capability
of Thermo-Lag 330-1 barriers, the ampacity derating of cables enclosed in
Thermo-Lag 330-1 barriers, and the evaluation and application of the results
of tests conducted to determine the fire endurance ratings and the ampacity
derating factors of Thermo-Lag 330-1 barriers.

The NRC is concerned that the Thermo-Lag 330-1 fire barrier systems may not
provide the level of fire endurance intended by licensees and, therefore, that
licensees that use Thermo-Lag 330-1 fire barriers may not be meeting the
requirements of Section 50.48, "Fire protection," and General Design Criterion
(GDC) 3, "Fire protection," of Appendix A, "General Design Criteria for
Nuclear Power Plants," to Part 50 of Title 10 of the Code of Federal
Regulations (10 CFR Part 50).  

Cables routed in electrical raceways are derated to ensure that systems have
sufficient capacity and capability to perform their intended safety functions. 
Cables routed in raceways enclosed in fire barriers require additional
derating because of the insulating effect of the fire barrier materials. 
Cable derating calculations that are based on inaccurate or nonconservative
derating factors could result in installation of undersized cables or raceway
overfilling.  This could cause operating temperatures to exceed design limits
within the raceways thereby reducing the expected design life of the cables. 
The NRC is concerned that because of the wide range of ampacity derating
factors documented for Thermo-Lag 330-1 materials, some licensees may not have
adequately accounted for the insulating effects of the Thermo-Lag material in
their derating analyses and, therefore, may not be meeting the requirements of
GDC 17, "Electric power systems."  This concern applies where Thermo-Lag 330-1
barriers are used either to protect safe shutdown capability from fire or to
achieve physical independence of electrical systems.  
.

GENERIC LETTER 92-08                 -3-              December 17, 1992


The NRC is also concerned that some licensees have not adequately reviewed and
evaluated the fire endurance test results and ampacity derating test results
used as the licensing basis for their Thermo-Lag 330-1 barriers to determine
the validity of the tests and the applicability of the test results to their
plant designs.

The NRC is requiring information needed to verify compliance with
10 CFR 50.48, GDC 3, and GDC 17, and associated license conditions under the
provisions of 10 CFR 50.54(f) where Thermo-Lag 330-1 barriers are used.  

FIRE ENDURANCE CAPABILITY

The NRC's Qualification Requirements and Guidance for Fire Barriers

Section 50.48 of 10 CFR requires that each operating nuclear power plant have
a fire protection plan that satisfies GDC 3.  GDC 3 requires that structures,
systems, and components important to safety be designed and located to
minimize, in a manner consistent with other safety requirements, the
probability and effects of fires.  Fire protection features required to
satisfy GDC 3 include features to ensure that one train of those systems
necessary to achieve and maintain shutdown conditions be maintained free of
fire damage.(1)  One means of complying with this requirement is to separate
one safe shutdown train from its redundant train with fire-rated barriers. 
The level of fire resistance required of the barriers, 1 hour or 3 hours,
depends on the other fire protection features provided in the fire area.  

The NRC issued guidance on acceptable methods of satisfying the regulatory
requirements of GDC 3 in Branch Technical Position (BTP) Auxiliary and Power
Conversion Systems Branch (APCSB) 9.5-1, "Guidelines for Fire Protection for
Nuclear Power Plants;" Appendix A to BTP APCSB 9.5-1; BTP Chemical Engineering
Branch (CMEB) 9.5-1, "Fire Protection For Nuclear Power Plants," July 1981;
and GL 86-10.  In the BTPs and in GL 86-10, the staff stated that the fire
resistance ratings of fire barriers should be established in accordance with
National Fire Protection Association (NFPA) Standard 251, "Standard Methods of
Fire Tests of Building Construction and Materials," by subjecting a test
specimen that represents the materials, workmanship, method of assembly,
dimensions, and configuration for which a fire rating is desired to a
"standard fire exposure" at a nationally recognized laboratory.(2)  In
GL 86-10, the staff included guidance on fire test acceptance criteria and for
evaluating deviations from tested configurations.


      (1) See Appendix R to 10 CFR Part 50, "Fire Protection Program for
Nuclear Power Facilities Operating Prior to January 1, 1979."

      (2) American Society for Testing and Materials (ASTM) Standard E119 was
adopted by the National Fire Protection Association (NFPA) as NFPA
Standard 251.

.

GENERIC LETTER 92-08                 -4-              December 17, 1992


Fire Endurance Testing and the Evaluation and Application of Fire Test Results

On October 26, 1989, the Southwest Research Institute (SwRI) performed
a 3-hour fire endurance test of a cable tray and support protected by a
Thermo-Lag 330-1 fire barrier for GSU.  SwRI found that temperatures within
the test assembly exceeded the NRC's acceptance criteria within 60 minutes and
that the test assembly collapsed in less than 90 minutes.  These test results
raised concerns about the adequacy of Thermo-Lag 330-1 cable tray enclosures. 
The staff informed the licensees of these test results in NRC IN 91-47,
"Failure of Thermo-Lag Fire Barrier Material to Pass Fire Endurance Test,"
August 6, 1991.  NRC IN 92-46 contains the staff's evaluation of this fire
test.

While conducting its review, the NRC staff found that many fire endurance
tests have been conducted on electrical raceways protected with
Thermo-Lag 330-1 fire barrier systems.  The staff reviewed about forty 1-hour
and 3-hour fire endurance test reports from various testing facilities and
found that testing methods and procedures used during some of the
qualification tests did not meet the NRC's guidance and deviated from good
engineering practices.  In NFPA 251, the NFPA advised that the test conditions
should be evaluated carefully because variations from the construction of the
test specimen or from the conditions in which it is tested may substantially
change the performance characteristics of the assembly.  The test reports
reviewed did not contain sufficient details of the construction methods used
for the test specimens, did not contain details of the materials used, and did
not contain dimensioned drawings.  Most of the test configurations were
atypical of the as-built field configurations observed by the staff.  

The NRC recognized that fire endurance testing of every as-built fire barrier
configuration is not possible.  In GL 86-10, the NRC issued guidance for
reviewing deviations from tested fire barrier configurations.  While reviewing
the Thermo-Lag 330-1 fire barriers, the NRC staff found several instances in
which licensees installed fire barrier configurations that may not have been
qualified by fire endurance testing or may not have been reviewed in
accordance with the guidance in GL 86-10.  For example, when the NRC conducted
its initial review, some licensees could not justify their practice of
extrapolating test results from small barrier enclosures to significantly
larger enclosures or installing barriers using procedures and materials that
were different from those tested.  The NRC visited five sites after issuing
IN 91-47 and also found several licensees that had constructed fire walls,
partitions, and vaults using Thermo-Lag 330-1 as a component.  These licensees
could not provide qualification test reports or justify deviations from tested
configurations to demonstrate the acceptability of these fire barriers.  The
staff informed the licensees of these issues in IN 91-79, "Deficiencies in the
Procedures for Installing Thermo-Lag Fire Barrier Materials,"
December 6, 1991.

The staff is concerned that some licensees have not adequately reviewed
applicable fire endurance test results to determine if the tests are valid and
if the test results apply to their plant designs.  

.

GENERIC LETTER 92-08                 -5-              December 17, 1992


Deficiencies in the Fire Barrier Installation and Inspection Procedures

While conducting site visits after issuing IN 91-47, the NRC staff observed
that the vendor had revised its recommended installation procedures without
notifying the licensees, that the vendor installation procedures are
incomplete, that a number of field installations were not constructed in
accordance with the vendor recommended installation procedures, that some
installations did not appear to be qualified by fire endurance testing, and
that some installations deviated from the tested configurations without
justification.  In IN 91-79, the NRC staff discussed installation problems
resulting from incomplete TSI installation procedures, inadequate licensee
installation procedures, installer errors, incomplete or incorrect design
documents, and inadequate quality control oversight.  In IN 91-79, the staff
also listed the installation details in which it found differences between the
field installations, the tested configurations, and the vendor installation
procedures.  These details are not repeated here.

AMPACITY DERATING

NRC Requirements and Guidance for Ampacity Derating

GDC 17 requires that onsite electric power systems be provided to permit the
functioning of structures, systems, and components important to safety.  The
onsite electrical power system is required to have sufficient capacity and
capability to ensure that vital functions are maintained.  The Institute of
Electrical and Electronics Engineers (IEEE) Standard 279, "Criteria for
Protection Systems for Nuclear Power Generating Stations," includes guidance
on acceptable methods of satisfying GDC 17.  IEEE states that the quality of
protection system components shall be achieved by specifying requirements
known to promote high quality, such as the requirements for the derating of
components, and that the quality shall be consistent with minimum maintenance
requirements and low failure rates.  Furthermore, IEEE 279 states that type
test data or reasonable engineering extrapolation based on test data shall be
made available to verify that protection system equipment continually meets
the performance requirements determined to be necessary for achieving the
system requirements.

In Regulatory Guide (RG) 1.75, "Physical Independence of Electric Systems,"
the NRC staff gave guidance for complying with IEEE Standard 279 and GDC 17
for the physical independence of the circuits and electric equipment
comprising or associated with the Class 1E power system, the protection
system, systems actuated or controlled by the protection systems, and
auxiliary or supporting systems that must be operable for the protection
system and the systems it actuates to perform their safety-related functions. 
Some licensees use Thermo-Lag 330-1 barriers to achieve physical independence
of electrical systems in accordance with RG 1.75.  The staff's concerns about
ampacity derating apply to Thermo-Lag 330-1 barriers installed to achieve
physical independence of electric systems and to those installed to protect
safe shutdown capability from fire. 

.

GENERIC LETTER 92-08                 -6-              Decmber 17, 1992


Ampacity Derating Tests and the Application of Ampacity Derating Test Results
Cables enclosed in electrical raceways protected with fire barrier materials
are derated because of the insulating effect of the fire barrier material. 
Other factors that affect ampacity derating include cable fill, cable loading,
cable type, raceway construction, and ambient temperature.  The National
Electrical Code, Insulated Cable Engineers Association (ICEA) publications,
and other industry standards provide general ampacity derating factors for
open air installations, but do not include derating factors for fire barrier
systems.  Although a national standard ampacity derating test method has not
been established, ampacity derating factors for raceways enclosed with fire
barrier material have been determined for specific installation configurations
by testing.

The vendor has documented a wide range of ampacity derating factors that were
determined by testing.  For example, between 1981 and 1985, the vendor
provided test reports to licensees that document ampacity derating factors for
cable trays that range from 5.3 to 12.48 percent for 1-hour barriers and
from 16.15 to 20.55 percent for 3-hour barriers.  On October 2, 1986, TSI
informed the NRC and its customers by Mailgram that, while conducting a
special services investigation in September 1986 at the Underwriters
Laboratories, Incorporated (UL), it found that the ampacity derating factors
for Thermo-Lag 330-1 barriers were greater than previous tests indicated
(28.04 percent for 1-hour barriers and 31.15 percent for 3-hour barriers). 
However, the cable fill and tray configuration for each test differed from
those tested previously.  The NRC learned that UL performed duplicate cable
tray baseline tests using a longer stabilization period (4 hours instead
of 15 minutes) after the final current adjustment and obtained a higher
baseline current, which yielded higher derating factors (36.1 percent
for 1-hour barriers and 38.9 percent for 3-hour barriers).  UL gave these test
results to the vendor, but they were not submitted to the NRC or to 
licensees.  While reviewing tests which had been conducted at SwRI in 1986,
the staff learned that the ampacity derating factor for the tested
configuration was 37.4 percent for a 1-hour Thermo-Lag 330-1 barrier.  The
test procedures and test configurations differed for each of the
aforementioned tests.  Therefore, the results from these different ampacity
tests may not be directly comparable to each other.

The staff is concerned that the ampacity derating factors derived from the UL
tests for similar Thermo-Lag 330-1 barrier designs are inconsistent with one
another because of differing stabilization times, which calls into question
the validity of the ampacity derating tests.  While reviewing Industrial
Testing Laboratories (ITL) test reports, the NRC staff noticed that ambient
temperature and maximum cable temperature were allowed to vary widely for some
tests (48 �C instead of 40 �C for ambient temperature and 94.4 �C instead
of 90 �C for maximum cable temperature).  ITL then used an ICEA procedure to
calculate the ampacity derating factors by adjusting the tested current
to 40 �C ambient and 90 �C cable temperature.  Those tests may not be valid
because the ambient and maximum cable temperatures were not maintained within
specified limits in some tests.  In IN 92-46, the NRC informed licensees that
a licensee also discovered a mathematical error in the calculation of the
ampacity derating factor as published in an ITL test report.  A preliminary
assessment of the use of lower-than-actual ampacity derating factors indicates
.

GENERIC LETTER 92-08                 -7-              December 17, 1992


that Thermo-Lag 330-1 barrier installations may allow cables to reach
temperatures that exceed their ratings, which could accelerate cable aging.

The staff is also concerned that some licensees have not adequately reviewed
the results of ampacity derating tests to determine if the tests are valid and
if the test results apply to their plant designs.  The staff ampacity derating
concerns apply to the use of Thermo-Lag 330-1 on electrical raceways both as
fire barriers to protect the safe shutdown capability and as barriers to

create physical independence between electrical systems.

ACTIONS REQUESTED

NRC regulations require that safe shutdown equipment be protected from fire,
that onsite electric power systems have sufficient capacity and capability to
ensure that vital functions are maintained, and that certain circuits and
electric equipment be physically independent.  The NRC has found test
assemblies that failed qualification fire tests, fire test results that are
incomplete and indeterminate, installation problems, questionable ampacity
derating tests, and differences between reported ampacity derating factors. 
The NRC also found that some licensees have not adequately evaluated the
results of tests for fire endurance and ampacity derating.  Therefore,
licensees are requested to confirm (1) that the Thermo-Lag 330-1 barrier
systems have been qualified by representative fire endurance tests, (2) that
the ampacity derating factors have been derived by valid tests, and (3) that
these qualified barriers have been installed with appropriate procedures and
quality controls to ensure that they comply with the NRC's requirements.

The staff is continuing to review technical issues associated with
Thermo-Lag 330-1 barriers.  The NRC staff will evaluate other fire barrier
materials and systems used by the licensees to satisfy the NRC's requirements. 
If the staff finds concerns, it will address them through appropriate
communications.  This generic letter does not request actions for barrier
materials and systems other than the Thermo-Lag 330-1 fire barrier system. 
However, the staff expects that the recipients of this generic letter will
review the information to determine if it applies to other barrier materials
and systems used at their facilities and consider actions, as appropriate, to
avoid similar problems.

REPORTING REQUIREMENTS

All addressees are required, pursuant to Section 182(a) of the Atomic Energy
Act of 1954, as amended, and 10 CFR 50.54(f), to submit a written report
within 120 days from the date of this generic letter.  In this written report,
the licensee shall address the following items.  Where applicable, the written
report can reference previous responses to Bulletin 92-01 and Supplement 1 to
Bulletin 92-01 in its response to this generic letter.

1.    State whether Thermo-Lag 330-1 barriers are relied upon (a) to meet
      10 CFR 50.48, to achieve physical independence of electrical systems,
      (b) to meet a condition of a plant's operating license, or (c) to
      satisfy a licensing commitment.  If applicable, state that
      Thermo-Lag 330-1 is not used at the facility.  This generic letter
      applies to all 1-hour and all 3-hour Thermo-Lag 330-1 materials and

.

GENERIC LETTER 92-08                 -8-              December 17, 1992


      barrier systems assembled by any assembly method such as by assembling
      preformed panels and conduit shapes, as well as spray, trowel and brush
      -on applications.

2.    If Thermo-Lag 330-1 barriers are used at the facility,

      (a)   State whether or not the licensee has qualified the
            Thermo-Lag 330-1 fire barriers by conducting fire endurance tests
            in accordance with the NRC's requirements and guidance or
            licensing commitments.

      (b)   State (1) whether or not the fire barrier configurations installed
            in the plant represent the materials, workmanship, methods of
            assembly, dimensions, and configurations of the qualification test
            assembly configurations; and (2) whether or not the licensee has
            evaluated any deviations from the tested configurations.  

      (c)   State (1) whether or not the as-built Thermo-Lag 330-1 barrier
            configurations are consistent with the barrier configurations used
            during the ampacity derating tests relied upon by the licensee for
            the ampacity derating factors used for all raceways protected by
            Thermo-Lag 330-1 (for fire protection of safe shutdown capability
            or to achieve physical independence of electrical systems) and
            (2) whether or not the ampacity derating test results relied upon
            by the licensee are correct and applicable to the plant design.

3.    With respect to any answer to items 2(a), 2(b), or 2(c) above in the
      negative, (a) describe all corrective actions needed and include a
      schedule by which such actions shall be completed and (b) describe all
      compensatory measures taken in accordance with the technical
      specifications or administrative controls.  When corrective actions have
      been completed, confirm in writing their completion.

4.    List all Thermo-Lag 330-1 barriers for which answers to item 2 cannot be
      provided in the response due within 120 days from the date of this
      generic letter, and include a schedule by which such answers shall be
      provided.

The licensee should retain all documentation of any reviews performed to
satisfy the reporting requirements for future NRC audits or inspections.

If the addressee cannot submit the information required or meet the reporting
deadline, it shall include in the response due within 120 days from the date
of this generic letter, a justification, a description of any proposed
alternative approaches, and a schedule under which responses and proposed
actions will be completed.  The NRC encourages licensees to work together to
develop acceptable generic solutions to the problems addressed in this generic
letter.

The written reports required shall be addressed to the U.S. Nuclear Regulatory
Commission, ATTN: Document Control Desk, Washington, D.C. 20555 under oath or
affirmation.  A copy of the report shall also be submitted to the appropriate
regional administrator..

GENERIC LETTER 92-08                 -9-              December 17, 1992


BACKFIT DISCUSSION

The types of barriers addressed in this generic letter are currently installed
at many operating power reactor sites and are required to meet either a
condition of a plant's operating license or NRC requirements such as
Section III.G of Appendix R to 10 CFR Part 50.  The information required by
this generic letter is necessary to verify licensees' compliance with their
current licensing bases.  There is no new staff position reflected in this
generic letter.  Therefore, any actions taken by licensees concomitant with
responding to this generic letter are necessary to bring licensees into
compliance with existing NRC rules and regulations, and are not the result of
any new staff requirement or position.  Accordingly, this generic letter is
being issued as a compliance backfit under the terms of 10 CFR
Section 50.109(a)(4).

The staff evaluated this generic letter in accordance with the charter of
Committee to Review Generic Requirements (CRGR) and will place that evaluation
in the NRC's public document room with the minutes of the October 6, 1992,
meeting of the CRGR. 

REQUEST FOR VOLUNTARY SUBMITTAL OF IMPACT DATA

This request is covered by Office of Management and Budget Clearance
Number 3150-0011, which expires June 30, 1994.  The estimated average number
of burden hours is 300 person-hours for each addressee's response, including
the time required to assess the requirements for information, search data
sources, gather and analyze the data, and prepare the required letters.  This
estimated average number of burden hours pertains only to the identified
response-related matters and does not include the time to implement the
actions required to comply with the applicable regulations, license
conditions, or commitments.  Comments on the accuracy of this estimate and
suggestions to reduce the burden may be directed to Ronald Minsk, Office of
Information and Regulatory Affairs (3150-0011), NEOB-3019, Office of
Management and Budget, Washington, D.C. 20503, and to the U.S. Nuclear
Regulatory Commission, Information and Records Management Branch, Division of
Information Support Services, Office of Information and Resources Management,
Washington, D.C. 20555.

Although not required, the following information would assist the NRC in
evaluating the cost of complying with this generic letter:

1.    The licensee staff time and costs to perform requested inspections,
      corrective actions, and associated testing;

2.    the licensee staff time and costs to prepare the required reports and
      documentation;

3.    the additional short-term costs incurred as a result of the inspection
      findings such as the costs of the corrective actions or the costs of
      down time; and.
      

GENERIC LETTER 92-08                 -10-             December 17, 1992


4.    an estimate of the additional long-term costs that will be incurred in
      the future to implement commitments such as the estimated costs of
      conducting future inspections or increased maintenance.

If you have any questions about this matter, please contact the technical
contact or the lead project manager listed below.

                                                                                                                                                                        Sincerely,


                                          ORIGINAL SIGNED BY


                                          James G. Partlow
                                          Associate Director for Projects
                                          Office of Nuclear Reactor Regulation


Enclosure:
List of Recently Issued Generic Letters


TECHNICAL CONTACT:      Steven West, U.S. Nuclear Regulatory Commission,
                        Office of Nuclear Reactor Regulation, Mail Stop 9 A2,
                        Washington, D.C. 20555, telephone (301) 504-1220

LEAD PROJECT MANAGER:   Armando Masciantonio, U.S. Nuclear Regulatory
                        Commission, Office of Nuclear Reactor Regulation, Mail
                        Stop 13 D18, Washington, D.C. 20555, telephone
                        (301) 504-1337


Page Last Reviewed/Updated Friday, June 28, 2013