April 19, 2005
Mr. Paul M. Golan
Acting Assistant Secretary for
U. S. Department of Energy
1000 Independence Avenue, SW
Washington, DC 20585-0113
Dear Mr. Golan:
On April 1, 2005, the Department of Energy Office of River Protection (DOE-ORP) approved the Interim Seismic Criteria (ISC) for the Waste Treatment Plant (WTP). †These criteria were prepared by the contractor, Bechtel National Incorporated (BNI), at the request of DOE-ORP, for use while final seismic criteria are being developed. †These criteria are needed to address the recently updated seismic hazard at the Hanford Site.
The ISC criteria will be used to evaluate near-term design and construction efforts in the following manner:
Ultimately, final seismic design criteria will be developed once BNIís structural models have been revised to incorporate the updated seismic hazard (currently forecast for August 2005).
BNI and DOE-ORP believe that the ISC adequately bound the seismic hazard at the Hanford Site and address the modeling issues raised previously by the Board (e.g., those related to mesh density). †However, the Board believes that uncertainties in the data used to develop the updated seismic spectra and in the proposed response to mesh density issues have not been fully addressed. †For example, uncertainty remains in the new seismic spectra because of a lack of specific site characterization data, including deep hole borings (collection of additional data is currently under study), and the magnitude of the load amplification factors strongly suggests considerable error in the crude mesh refinement used in BNIís modeling approach.
Given these uncertainties and the remaining uncertainty inherent in the design-build process, it is the Boardís view that:
The use of the ISC creates the potential for future design changes or rework. †To minimize this risk, its use should be limited to as short a period as possible and every effort made to develop acceptable final design criteria. †If you have any questions on this matter, please do not hesitate to contact me.
A. J. Eggenberger
c: ††Mr. Roy J. Schepens
Mr. Mark B. Whitaker, Jr.