**\[DOE LETTER HEAD\]**

**NATIONAL NUCLEAR SECURITY ADMINISTRATION**

December 17, 2007

The Honorable A. J. Eggenberger

Chairman

Defense Nuclear Facilities Safety Board

625 Indiana Avenue, N.W., Suite 700

Washington, D.C. 20004-2901

Dear Chairman Eggenberger:

This is in response to your September 10, 2007, letter requesting a
report regarding the National Nuclear Security Administration\'s (NNSA)
utilization of the Materials Accountability and Safeguards System (MASS)
at the Los Alamos National Laboratory

(LANL).

NNSA Headquarters\' review of the LANL criticality safety program raised
concerns regarding the potential for improper use of MASS as a
criticality safety control system in

2005\. During the past year, the Los Alamos Site Office (LASO)
identified improper utilization of MASS for criticality safety purposes
as a causal factor in a criticality safety infraction involving a
mismatch between designated item locations in MASS and posted
criticality safety limits on August 15, 2007. The specific issues
identified in your letter are addressed below.

1.  \"Identification of the safety functions that MASS currently
    performs and upon which management relies, and all new safety
    functions which will be incorporated into the upgraded system.\"

The LANL description on the use of MASS is provided as an enclosure. It
describes LANL\'s use of MASS as a Safeguards Nuclear Material Control
and Accountability (MC&A) software system that provides a convenient
operator aid for tracking fissionable material masses. Operator
understanding and compliance with criticality safety limits is a
procedural and safety management programmatic requirement implemented
independently of the MASS system. MASS is not relied upon to perform a
criticality safety function and, therefore, requires no upgrades for
criticality safety purposes. LANL is in the process of modifying safety
procedures and retraining facility staff to ensure that

MASS is used only for its intended purpose.

2.  \"Discussion of the process for incorporating these new requirements
    into an improved MASS, and how lessons learned from previous upgrade
    attempts, including the need for strong project leadership, have
    been captured in the upgrade strategy and milestones.\"

NNSA has no plan to incorporate criticality safety requirements into
MASS. MASS cannot be used as an effective tool for criticality safety
because criticality safety limits typically depend upon parameters other
than fissionable material mass (e.g., shape, form, enrichment, spacing,
etc.) that a safeguards MC&A does not, and should not, capture and
track.

> 3\. \"Compensatory measures to ensure the safety of material movements
> before the
>
> MASS upgrade has been completed.\"

LANL is in the process of modifying safety procedures and retraining
facility staff to ensure that MASS is used only for its intended MC&A
purpose. NNSA has no plans to perform criticality safety related
upgrades for MASS.

> 4\. \"Specific actions the NNSA will take to ensure the success of the
> MASS upgrade.\"

As noted above, NNSA has no plans to perform criticality safety-related
upgrades for

MASS. However, LASO will provide operational oversight coupled with two
formal assessments in Fiscal Year 2008 using selected requirements from
DOE-STD-1158-2002 to ensure the actions detailed in the enclosure are
successful in eliminating any real or apparent reliance on MASS for
criticality safety issues.

If you have any questions, please contact me or Dr. Jerry McKamy at
301-903-8031.

Sincerely,

***Thomas P. D'Agostino***

***Administrator***

[Enclosure](../AttachedFile/tb07d17a_enc.pdf)

cc: D. Winchell, AL

> R. Smolen, NA-10
>
> M. Whitaker, NA-2.1
>
> B. Ostendorff, NA-2