**\[DNFSB LETTERHEAD\]**

June 26, 2006

Mr. C. Russell H. Shearer

Acting Assistant Secretary for Environment, Safety, and Health

1000 Independence Avenue, SW

Washington, DC 20585-1000

Dear Mr. Shearer:

The Defense Nuclear Facilities Safety Board (Board) has been following
the implementation of Department of Energy (DOE) Standard 1027-92,
*Hazard Categorization and Accident Analysis Techniques for Compliance
with DOE Order 5480.23*, *Nuclear Safety Analysis Reports, Change Notice
1* (Standard 1027). This standard provides the safe harbor methodology
for hazard categorization for compliance with 10 Code of Federal
Regulations (CFR) 830, *Nuclear Safety Management*, and describes the
processes to be used in arriving at the preliminary and final hazard
categories for nuclear facilities. These hazard categorizations in turn
dictate the rigor of the safety analysis required for compliance with
the rule.

Since hazard categorization is the first step in safety analysis for a
facility, it is important for the standard that guides this process, as
well as its implementation, to be clear and consistent across the
complex. In the course of the Board's review, however, it has become
evident that there is a lack of clarity in aspects of Standard 1027, as
well as inconsistency in the interpretation and application of the
ground rules described in the standard.

The enclosures to this letter identify examples of the lack of clarity
and inconsistent application of Standard 1027. The identified
inconsistencies may have resulted in nonconservatism in the hazard
categorization of facilities, analysis of accident scenarios, and
selection and implementation of safety-related controls. Further review
of Standard 1027 and of how it has been applied in the DOE complex may
identify other areas in need of improvement.

The Board believes additional guidance is needed to ensure that defense
nuclear facilities apply Standard 1027 consistently and correctly.
Therefore, pursuant to 42 U.S.C. § 2286b(d), the Board requests that,
within 120 days of receipt of this letter, DOE issue a report that
addresses the following:

-   A review of Standard 1027 for areas that might benefit from
    improvement, including the problems described in the enclosure to
    this letter.

-   Identification of any defense nuclear facilities affected by
    problems identified during the review of Standard 1027.

-   The path forward to address these problems in any affected nuclear
    facilities and to prevent these problems in the future.

Sincerely,

***A. J. Eggenberger***

***Chairman***

c: The Honorable Linton Brooks

The Honorable James A. Rispoli

Mr. Mark B. Whitaker, Jr.

Enclosure

**Enclosure**

During several reviews of DOE Standard 1027, *Hazard Categorization and
Accident Analysis Techniques for Compliance with DOE Order 5480.23*,
*Nuclear Safety Analysis Reports*, Change Notice 1 (Standard 1027), the
Board's staff identified multiple issues associated with the
implementation of the standard. These include lack of clarity in
requirements for exclusion of sealed sources from facility inventory,
inconsistencies in expectations regarding implementation of Nuclear
Criticality Safety (NCS) controls, and an unclear technical basis for
the calculation of threshold values listed in the standard.

**Sealed-Source Exclusions.** While facility hazard categorizations are
based largely on inventory, Standard 1027 does permit excluding from the
materials at risk inventory that meets certain criteria, such as
Department of Transportation (DOT) special-form testing for sealed
sources (49 CFR 173.469) or American National Standards Institute (ANSI)
Standard N43.6, *Sealed Radioactive Sources―Classification*. DOT
special-form fire testing requirements for sealed sources include being
heated in air at greater than or equal to 800°C for 10 minutes and then
being cooled. The test requirements for ANSI sealed sources vary from no
test for class 1, to 600°C and 800°C for 1 hour, respectively, for
classes 5 and 6. The ANSI standard farther states that these
temperature-based performance requirements do not take into account
direct exposure of the source to fire and that the manufacturer and user
must consider the probability of fire and possible results, including
the consequences of loss of integrity.

It is, however, important that these sources be capable of surviving a
fire, as fire is usually the dominant accident scenario for nuclear
facilities; analyses typically predict temperatures in the 400°C to
600°C range or higher for fires with moderate combustible inventories
and without fire suppression. Another evaluation-basis fire is
represented by the time-temperature curve given in ASTM International
Standard El 19, *Standard Test Methods for Fire Tests of Building
Construction Materials*; this curve reaches 800°C after about 25 minutes
and 925°C in 60 minutes.

With the possible exception of ANSI class 5 and 6 sealed sources, it
appears the above testing requirements would not demonstrate that the
integrity of sealed sources is maintained under a representative
unmitigated fire scenario (e.g., 400°C to 600°C range or higher).
However, some DOE sites have credited generic sealed-source
encapsulation, as permitted by Standard 1027, for excluding radioactive
inventory from consideration as material at risk, thereby making it
possible to downgrade Hazard Category 2 and 3 nuclear facilities to
Radiological facility status.

In some cases, the exclusion has also been inappropriately extended to
include radioisotope sources not intended to be treated as sealed
sources. For example, Pu^238^ heat sources have been excluded from
facility inventories for hazard categorization purposes; however, such
sources do not fall within the definition of sealed sources in 10 CFR
835, Occupational Radiation Protection because of the potential internal
doses to workers and the public should the integrity of the source be
compromised.

**Treatment of Criticality.** With regard to criticality, Standard 1027
states that Hazard Category 2 facilities include those containing
fissile material in quantities greater than the limits for criticality
emergencies specified in American National Standards Institute (ANSI)
and American Nuclear Society (ANS) 8.1-1983, R88, *Nuclear Criticality
Safety in Operations with Fissionable Materials Outside Reactors*. For
aqueous solutions of uranium-233 (U^233^), U^235^, and plutonium-239
(Pu^239^) these values are 500, 700, and 450 grams, respectively.
Standard 1027 allows credit to be taken if segmentation or "nature of
process" precludes the potential for a criticality accident. Facilities
that exceed these fissile mass limits but do not meet either of the
criteria are to be designated as Hazard Category 2 because of the
potential for criticality alone.

DOE-Headquarters appears to consider the presence of defined Nuclear
Criticality Safety (NCS) controls in a facility as implying the
potential for criticality. This, combined with the explicit treatment of
criticality potential in Standard 1027, has been interpreted to mean
that whenever the need for an NCS control is identified, the facility is
to be designated Hazard Category 2 by default.

The current approach endorsed by DOE-Headquarters has proven to be a
potential impediment to implementation of appropriate controls. Some
contractors have chosen to avoid the use of formal NCS controls in order
to avoid an automatic designation of Hazard Category 2 for a given
facility or activity. The purpose of Standard 1027 is to establish
guidance for the preparation and review of hazard categorization and
accident analyses; it is not to determine whether controls are required.
For DOE-Headquarters to assert that derived controls affect the hazard
categorization contradicts the statement in Standard 1027 that the
graded approach "does not relieve the contractor\....from the obligation
to maintain and operate the facility safely and efficiently."
Designation of a facility as less than Hazard Category 2 should not
hinder the contractor from implementing controls that protect
assumptions.

The Board notes that the NCS requirements, when implemented properly,
provide a robust set of controls for fissile material handling
regardless of the hazard categorization of the facility, DOE should
revisit the rationale for the automatic Hazard Categorization 2
designation for facilities with a potential for criticality.

**Technical Basis for Threshold Values.** Standard 1027 allows a
facility initially categorized as Hazard Category 2 to be categorized as
Hazard Category 3 in the final categorization process. This can be
accomplished by adjusting the threshold quantities against which the
facility inventory is compared if the release fractions can be shown to
be significantly different from those used in calculating the threshold
quantities listed in Attachment 1 to the standard. However, the standard
does not explicitly extend this allowance to facilities initially
categorized as Hazard Category 3.

In 2002, the Office of Environment, Safety, and Health (EH-1) issued a
Nuclear Safety Technical Position, NSTP 2002-2, *Methodology for Final
Categorization for Nuclear Facilities from Category 3 to Radiological*
(NSTP), to address the lack of a specific allowance for adjusting the
threshold quantities. According to the technical position, for a
facility initially categorized as Hazard Category 3, the threshold
values may be revised for the purposes of final hazard categorization if
the release fractions are substantially different from those used in the
calculation of the threshold values listed in Attachment 1 to the
standard.

The methodology for the derivation of and adjustment of Hazard Category
2 threshold values, including release fractions to be used, is described
wholly within Standard 1027.

However, similar information for the Hazard Category 3 threshold values
is not given in Standard 1027. Rather, Standard 1027 makes a vague
reference to a user\'s manual for a radionuclide database that does not
explicitly discuss the assumptions used in calculating the threshold
values. EH-1's NSTP cites another document, *Technical Background
Document to Support Final Rulemaking Pursuant to Section 102 of the
Comprehensive Environmental Response, Compensation, and Liability Act:
Radionuclides: A Report to the Emergency Response Division, Office of
Emergency and Remedial Response, U.S. Environmental Protection Agency
(EPA)*. As with Standard 1027, this document does not provide specifics
for adjusting Hazard Category 3 threshold values.

Ultimately, through nested references, both Standard 1027 and the EH-1
NSTP lead to the same technical basis for the release fractions used in
calculating the Hazard Category 3 threshold quantities. The staff notes
that the technical basis and release fractions for calculating the
Hazard Category 3 threshold values are different than those used for
Hazard Category 2 threshold values. However, because Standard 1027 and
the NSTP are vague, a site analyst could easily assume that the Hazard
Category 3 threshold values could be adjusted using the methodology and
release fractions for Hazard Category 2 listed in Standard 1027.

One example illustrates this point. On August 11, 2003, the Nevada Site
Office approved the Lawrence Livermore National Laboratory Core Library
for operation as a radiological facility. A review of the June 2, 2003
request from the contractor, however, revealed that the Hazard Category
3 threshold values for several radionuclides including nickel-63,
technetium-99, europium-152, and europium-154 were adjusted assuming
that a release fraction value of l0^-3^ was used in calculating the
threshold values listed in Standard 1027. However, 10^-3^ is the release
fraction used to calculate the Hazard Category 2 threshold values.
According to the EPA model, the actual release fraction used in
calculating the Hazard Category 3 threshold values is 10^-2^ for these
nuclides. The result is that the threshold values against which the
facility inventory was compared were a factor of 10 higher than they
would have been had the correct release fractions been used.