**\[DNFSB LETTERHEAD\]**

February 11, 2005

Mr. Paul M. Golan

Acting Assistant Secretary for

Environmental Management

U.S. Department of Energy

1000 Independence Avenue, SW

Washington, DC 20585-0113

Dear Mr. Golan:

As accelerated deactivation and decommissioning (D&D) work is performed
at the Department of Energy's (DOE) defense nuclear facilities,
continued vigilance must be maintained to ensure that an inadvertent
criticality accident does not occur.

Enclosed is a report detailing observations made by members of the staff
of the Defense Nuclear Facilities Safety Board (Board) concerning
criticality safety issues at the Plutonium Finishing Plant at the
Hanford Site. Two recent assay errors involving kilogram quantities of
plutonium have occurred. The amount of plutonium involved is sufficient
to result in a criticality accident under abnormal conditions. The root
causes of these errors appear to be a lack of trained personnel and
inadequate criticality safety procedures. These same deficiencies were
identified by DOE during reviews and assessments conducted in 2003,
prior to the start of D&D work in the Plutonium Finishing Plant. DOE
also noted in its 2003 assessment that the Fluor Hanford Senior Nuclear
Criticality Safety Committee had been disbanded, and that there was no
evidence of a corporate strategy for criticality safety as facilities
transition from production work to D&D. Effective corrective actions are
needed to ensure that an inadvertent criticality accident is prevented.

On a broader scale, the fact that appropriate DOE criticality experts
identified these issues in 2003, but were unable to ensure they were
addressed, indicates that DOE's Nuclear Criticality Safety Program is
not yet performing at an adequate level. DOE did not fully recognize the
seriousness of the problems or appreciate the potential for criticality
accidents. As a result DOE failed to ensure that the contractor had
adequate trained personnel and adequate criticality safety procedures
for the D&D work.

Therefore, pursuant to 42 U.S.C. § 2286b(d), the Board requests a
briefing within 60 days of receipt of this letter that addresses the
corrective actions being taken in response to the recent assay errors
and the related issues discussed in the enclosed report.

Sincerely,

***John T. Conway***

***Chairman***

c: Mr. Keith A. Klein

Mr. David H. Crandall

Mr. Mark B. Whitaker, Jr.

Enclosure

**DEFENSE NUCLEAR FACILITIES SAFETY BOARD**

**Staff Issue Report**

December 28, 2004

**MEMORANDUM FOR:** J. K. Fortenberry, Technical Director

**COPIES:** Board Members

**FROM:** W. Yeniscavich

**SUBJECT:** Nuclear Criticality Safety Issues at the Plutonium
Finishing Plant

**Purpose.** This report documents criticality safety issues identified
by members of the staff of the Defense Nuclear Facilities Safety Board
(Board) during a visit to the Plutonium Finishing Plant (PFP) at the
Hanford Site on October 5 and 6, 2004. The report also includes
information obtained in subsequent discussions with personnel from the
Department of Energy's Richland Operations Office (DOE-RL) and Fluor
Hanford, and during a review of documents received after the site visit.
Members of the Board's staff involved in this review were W.
Yeniscavich, J. Roarty, L. Zull, H. Massie, and D. Grover.

**Background.** The removal of the bulk plutonium inventory from the
processing equipment in PFP was completed in February 2004, and plant
workers have initiated deactivation and decommissioning (D&D)
activities. There are 232 gloveboxes and hoods and other areas that
contain plutonium holdup.

*DOE Review of Nondestructive Assay (NDA) Program*―In August 2003,
DOE-RL, assisted by Facility Operations Support (EH-24), performed a
review of the NDA program at PFP. The main purpose of the review was to
determine the adequacy of the program to support the upcoming D&D
mission. The review revealed that the NDA program and its associated
infrastructure, including such aspects as staffing, equipment
availability, training programs, organization, and specific measurement
methods and techniques, were not adequate to support planned D&D
activities at PFP.

The report documenting the August 2003 review noted that improvements
were needed in training NDA operators to understand the specific factors
that affect measurements; that PFP did not have a stand-alone,
documented NDA program such as that implemented at the Rocky Flats
Environmental Technology Site during D&D activities; and that there was
no nationally recognized senior scientist on the NDA staff at PFP.
Specific areas requiring improvement were not called deficiencies, but
were treated as suggestions and called "opportunities for improvement."

*DOE* Review *of Nuclear Criticality Safety Program*―In October 2003,
personnel from DOE's Office of Safety and Engineering (EM-5) performed
an assessment of the nuclear criticality safety program at Fluor Hanford
facilities. The assessment focused on PFP because this facility had
reported the majority of criticality nonconformances. The assessment
report noted that the Nuclear Criticality Safety Program was well
documented and comprehensive, but the report also contained several
observations and recommendations for the contractor to review and
identify appropriate corrective actions. The report reiterated the
finding of the August 2003 NDA review that NDA operators needed training
on NDA techniques. In addition, the report noted that the Fluor Hanford
Senior Nuclear Criticality Safety Committee had been disbanded, and that
a corporate strategy was not evident for maintaining criticality safety
while transitioning from operations to D&D.

**Plutonium Mass Errors in Glovebox HA-9A.** Plutonium holdup on the
interior walls and floors of a glovebox is determined by NDA. Plutonium
holdup inside equipment within a glovebox is also usually determined by
NDA. PFP analysts stated that in some cases, shielding by equipment
prevents accurate NDA measurements of holdup in the equipment. The
alternative is to develop an engineering estimate of holdup.

In May 2004, NDA measurements were made and the fissile mass holdup in
glovebox HA-9A was calculated. The glovebox was reassayed in September
2004, and it was discovered that the May calculations for fissile mass
were too low by a factor of approximately three. When these assays were
performed, the detector was shielded with a 1/4-inch lead disc to
improve the detector's performance. In the May calculations, however,
the correction factor for the lead disc was not included in the assay
calculation, resulting in the low assay results. The May data and
calculations were reviewed by a second and then by a third NDA scientist
without the error being detected.

A second error in the same glovebox was discovered by PFP personnel on
October 6, 2004. The engineering estimate of plutonium mass within
equipment in the glovebox was not provided to the group responsible for
tracking glovebox inventories. As a result, the plutonium mass for
glovebox HA-9A was under-recorded. The plutonium holdup in the equipment
was not included in the NDA measurements because attenuation caused by
the density of the equipment would have led to inaccurate results.
Instead, an engineering estimate of plutonium holdup in the equipment
was developed. The estimate of plutonium holdup in equipment is normally
provided along with the letter providing the NDA results. In this case,
the estimated plutonium holdup in the equipment was not attached to the
NDA results letter, and as a result, the plutonium holdup in the
equipment was not included in the glovebox inventory.

**Contractor's Identification of Apparent Causes.** Contractor personnel
reviewed the deficiencies related to glovebox HA-9A and developed the
following list of apparent causes:

-   For the NDA calculation error:

    -   The option for including lead shielding in the calculation was
        not selected.

    -   The two reviewers did not catch the error.

    -   There was time pressure to complete a large workload.

-   For the glovebox fissile inventory error:

    -   The NDA results letter provided for inventory management did not
        include the holdup in equipment, and no one recognized that the
        data were missing.

    -   The glovebox inventory tracking process did not have a formal
        method for including data not acquired by the NDA.

**Contractor's Corrective Actions.** Contractor personnel developed a
list of 18 suggested corrective actions. Many are short-term immediate
actions, such as suspending work and correcting immediate errors. The
longer-term corrective actions include hiring additional NDA personnel
and implementing a formal checklist for processing and reviewing NDA
data. To address the glovebox inventory error, contractor analysts
proposed creating a process to prevent a recurrence, the details of
which remain to be developed.

DOE-RL personnel noted that the NDA review process needs to be more
rigorous, and that PFP has undergone a significant loss of experienced
personnel. DOE-RL managers believe it would have been apparent to
experienced operations personnel, based on process knowledge, that the
NDA calculation for glovebox HA-9A was in error. No individual with
process experience was involved in the review of the new NDA data; thus,
the data were accepted without question.

**Issues To Be Addressed.** Based on the information obtained during
this review, the Board's staff has identified the following issues
associated with the criticality safety program at PFP:

-   It appears that the recent NDA and inventory errors were the result
    of informal procedures and a lack of knowledge on the part of
    personnel doing the work. The contractor indicated that a more
    formal procedure will be developed. However, the contractor gave no
    indication that additional training of operators is planned. The
    final corrective actions and implementation plan for addressing
    these recent errors have not yet been completed.

-   It is not clear that the findings and observations from DOE's August
    2003 review and assessment resulted in the adequate formulation and
    implementation of corrective actions for the deficiencies. The
    Board's staff noted that the results of DOE's review and assessment
    were identified as suggestions, not findings, to be implemented at
    the contractor's discretion.

-   There needs to be a process for determining the effectiveness of
    implementation of corrective actions. For example, at the Rocky
    Flats Environmental Technology Site, independent assessments of the
    NDA program were conducted by senior individuals (some outside
    experts) experienced in this area.

-   Reliance on only NDA to determine the plutonium holdup contributed
    to the incorrect mass assessment. NDA should be checked against
    historical records. In the absence of historical records,
    engineering estimates should be made to confirm the NDA results.
    This cross-checking of holdup estimates would increase the
    reliability of plutonium mass assessments.

-   The use of engineering estimates as the only determination of
    plutonium holdup should be avoided. Additional effort should be made
    to measure plutonium holdup. Improved training in NDA techniques may
    allow measurements to be made that were previously thought
    impossible. Modified techniques other than standard NDA ought to be
    considered for measuring plutonium holdup in equipment.

-   DOE's October 2003 assessment of the criticality safety program
    revealed that a corporate strategy was not evident for maintaining
    criticality safety while transitioning from operations to D&D. A
    clear strategy needs to exist for maintaining criticality safety
    when shifting from production operations to D&D. An effective Senior
    Nuclear Criticality Safety Committee is also vital to maintaining
    criticality safety.