**\[DOE LETTER HEAD\]**

**December 21, 2007**

Idaho Operations Office

1955 Fremont Avenue

Idaho Falls, ID 8341 5

Mr. J. K. Fortenberry

Defense Nuclear Facilities Safety Board

625 Indiana Avenue, NW, Suite 700

Washington, D.C. 20005-290 1

SUBJECT: The Department of Energy, Idaho Operations Office Sodium
Bearing Waste

> Treatment Project Summary of Actions to the Defense Nuclear Facilities
> Safety
>
> Board Statements Regarding the Geotechnical and Seismic Investigations
>
> Associated with the Integrated Waste Treatment Unit Facility Design
>
> (FMDP-MTPP-07-0 17)

Reference: 1) The Department of Energy, Idaho Operations Office Sodium
Bearing Waste

> Treatment Project Response to the Defense Nuclear Facilities Safety
> Board
>
> Questions Regarding the Geotechnical and Seismic Investigations
> Associated with
>
> the Integrated Waste Treatment Unit Facility Design (FMDP-MTPP-07-0
> 1*5),*
>
> Memorandum from Elizabeth D. Sellers, Manager, Idaho Operations Office
> to Mr.
>
> J. K. Fortenberry, Defense Nuclear Facilities Safety Board, dated
> October 1, 2007
>
> 2\) Integrated Waste Treatment Unit (IWTU) Idaho National Laboratory,
> Kleinfelder
>
> Report, Project No 76388, Revision 0, June 5, 2007

Dear Mr. Fortenberry:

This letter provides the summary of actions taken and responses to the
three remaining questions

regarding the geotechnical and seismic investigations for the Integrated
Waste Treatment Unit

(IWTU) facility design. The scope and schedule to address these three
questions was provided in

reference 1. Implementation of this work has entailed ongoing dialogue
between your staff and

the IWTU project staff. The confirmation analyses that have been
performed, based on the

results of these actions, demonstrate that the facility design (with
minor modifications) meets the

requirements of the applicable consensus codes and DOE standards. Demand
to capacity ratios

for the structural elements are less than 1.0 when the appropriate
factors (SF, F,) per DOE-STD-

1020 are applied. The results of the Soil Structure Interaction (SSI)
analysis that incorporated

the three actions were discussed between DOE, CH2M+WG Idaho, LLC (CWI)
and Simpson

Gumpertz & Heger (SGH) staff and your staff on December 12, 2007.

Mr. J. K. Fortenberry -2- FMDP-MTPP-07-0 17

The results of our actions to address the three DNFSB staff statements
are summarized below:

1\. The design basis earthquake response spectra are artificially low
due to use of the mean

> from the site specific soils spectra data.
>
> Action Taken: The Project developed the broadened horizontal and
> vertical 84th
>
> percentile spectra with 5% damping using the randomized soil column
> profiles based on
>
> the site specific geotechnical studies, reference 2. This action
> increased the target 5%
>
> damped spectra from the peak horizontal acceleration of 1.1 g
> recommended by the
>
> IWTU Blue Ribbon Panel (BRP) to about 1.25 g, which was then used as
> the basis for the
>
> following two actions.

2\. The geotechnical input for the engineered fill using the technical
approach relying on a

> thesis paper was not justified. Action Taken: Members of the IWTU Blue
> Ribbon Panel (BRP) and DOE technical
>
> experts met on October 3 and 4, 2007 to discuss the DNFSB staffs
> issues. Regarding the
>
> modeling of the soil and its properties, the BRP recommended: 1) that
> minor changes be
>
> made to the finite element model in the area of the base slab, using
> brick rather than plate
>
> elements, and 2) an approach that bounded the site-specific data by
> establishing four soil
>
> property cases (lower bound (LB), best estimate (BE), upper bound
> (UB), and high bound
>
> (HB)) that were deemed to adequately bounded the expected range of
> soil and engineered
>
> fill response. The modeling and changes to the LB, BE, and UB cases
> had no appreciable
>
> impact to the design, as determined in comparisons of the base shear
> for the various cases
>
> that has been run throughout the design effort. The HB case increased
> the base shear in
>
> the walls by 15% to 25%, which the confirmation analysis demonstrated
> could be
>
> accommodated with adequate margin.

3\. The time histories used in the SSI analysis should be evaluated
matching both the 5%

> damped and 13% damped values, appropriately broadened horizontal and
> vertical IWTU
>
> PC3 soil design basis earthquake response spectra from item I.

Action Taken: The SSI analysis responses used in the original design
represented the

highest SSI system mode damping of 13%. The December 2007 confirmation
analyses,

using the IWTU BRP recommended four soil profiles, produced SSI
responses yielding a

highest SSI system damping of 14%. Therefore, the Project matched the
time histories to

5% and 14% damped spectra for the SSI analyses. The Project also
confirmed that the

time histories matched or exceeded the 84th percentile spectra at 5%
damped value

proposed by the IWTU BRP at the surface of the IWTU project. The
modification to the

time histories had the single largest effect on the analytical results.
The base shear in the

final analysis was 33% to 45% higher than that of the original analysis.
The results of the

final analysis were also compared to a new SSI run using the final model
and soil

properties and the time histories from the original analyses. The final
model and matched

time histories resulted in base shear that was 65% higher than those
calculated using the

final model and original time history.

Mr. J. K. Fortenberry -3**-** FMDP-MTPP-07-017

Global (or integrated load) checks as well as element by element reviews
of the analytical results

using these more conservative inputs indicate that the demand to
capacity ratios (DIC) for the

IWTU structural design are still less than 1.0 when the appropriate
factors from DOE-STD-1020

and consensus codes are taken into consideration. Because the DIC is
less than 1.0 the design

meets all applicable criteria. Also as discussed at the December 12,
2007 meeting, the project

will review the final results with Dr. Carl Constantino and other
members of the IWTU BRP.

An additional meeting, per your staff request, is also planned with your
staff the first week of

January 2008 to review the details of the structural design,
particularly those associated with the

process cell walls.

We consider that the actions to address the three outstanding issues are
complete. Concrete

placement of the process cells walls will proceed, as scheduled, in
mid-January.

If you or your staff has any question regarding this path forward please
contact me at 208-526-

5665 or Mr. Guy Girard, the SBW Treatment Project Federal Project
Director, at 208-520-0524.

> Elisabeth D. Sellers
>
> Manager

cc:

D. Chung, EM-60

K. Picha, EM-60

M. Whitaker, HS-1.1

[Attachment](http://www.hss.energy.gov/deprep/2007/AttachedFile/TB07D21c_enc.pdf)