[DNFSB LETTER HEAD]
May 1, 2008
The Honorable James A. Rispoli
Assistant Secretary for Environmental Management
U. S. Department of Energy
1000 Independence Avenue, SW
Washington, DC 20585-0113
Dear Mr. Rispoli:
The Defense Nuclear Facilities Safety Board has completed a series of reviews related to
the development and analysis of design basis ground motion supporting structural design of the
Integrated Waste Treatment Unit (IWTU). These reviews revealed a number of issues related to
the development of the design basis ground motion and overall seismic design for the facility.
Some of the key issues were:
inconsistent with site-specific soil data
including issues related to strain-compatible soil properties
cranes which could impact structural adequacy
As a result of significant efforts made by the Department of Energy’s Idaho Operations
Office (DOE-ID) and the IWTU structural designer, Simpson, Gumpertz & Heger (SGH), all issues
were resolved, and appropriate changes to the design were made. Both DOE-ID and SGH
are to be commended for resolving these issues in an expeditious manner.
Two key actions were responsible for the successful resolution of these Board issues.
First, SGH incorporated conservatism into the original design of the Performance Category 3
process and packaging cells. As a result, the process and packaging cells design WIS able to
accommodate a substantial increase in design basis ground motion without demands exceeding
structural capacity. Second the project formed a geotechnical and SSI peer review panel (named
the Blue Ribbon Panel) that provided critical advice on incorporating appropriate soil properties
into the SSI analysis. The panel provided an essential peer review process that went a long way
toward strengthening the technical credibility of the IWTU design. The Board believes the use of
peer review panels would benefit all DOE design efforts.
Please contact me if you have any questions on this matter.
Ms. Elizabeth D. Sellers
Mr. Mark B. Whitaker, Jr.
Mr. Robert J. McMorland