[DNFSB LETTERHEAD]
December 16, 2002
The Honorable Spencer Abraham
Secretary of Energy
1000 Independence Avenue, SW
Washington, DC 20585-1000
Dear Secretary Abraham:
In a letter dated July 30, 2002, the Defense
Nuclear Facilities Safety Board (Board) evaluated estimates of maximum
increases in design load that might arise from various seismic-related
uncertainties associated with the design of the Waste Treatment Plant. The Board deemed these uncertainties to be
acceptable given the margins then being used in the development of the
design. Many of these uncertainties
remain, however, and the Board sees a continued need for careful management of
these and other design margins.
The Board believes that the Department of
Energy (DOE) and Bechtel National Incorporated have not instituted a formal
strategy for maintaining design margins as a function of design
uncertainties. For example, the Board
recently learned that the demand-to-capacity ratio limit of 0.85 applied to the
structural design will be maintained only for the basemat and walls to grade
and not for other portions of the high-level waste structure. At this time the design of the upper
portions of the structure remains largely incomplete and uncertain and hence
should reflect design margins. The
approach of erosion of margins does not appear to be reasonable since it is the
Board’s experience that problems manifest themselves throughout the process of
design development. Specifically,
structural design margins should be reduced only after more detailed design
development has been completed and/or a better understanding of the specific
hazards (e.g., the seismic hazard) has been gained. This is not the case for the current Waste Treatment Plant
structural design or the development of any new information related to the
seismic hazard.
The Board is also concerned about the
federal oversight of this project. The
Board believes that the recent decision by DOE to authorize construction of the
High-Level Waste, Low-Activity Waste, and portions of the Pretreatment
facilities should be followed by more detailed assessments of the design to
identify and address potential problems before they manifest themselves as
significant safety issues. The Board
recognizes that DOE used the Safety Evaluation Report as the basis for
authorizing construction, but also believes that DOE has yet to initiate a
program of design reviews at a sufficient level of detail to identify potential
problems and ensure that they are being addressed properly. As an example, the Board is particularly
concerned that the current structural design for the High-Level Waste facility
could result in levels of seismic floor response that would significantly
challenge the ability of safety systems and equipment to withstand seismic
loadings.
To address this challenge, more robust
equipment would need to be procured and more robust equipment supports
installed. Until recently, this problem
was largely unrecognized by DOE. Since
this facility is critical for long-term risk reduction at the Hanford site, the
Board believes DOE needs to take every precaution to ensure that it will be
properly designed and constructed.
Therefore, pursuant to 42 U.S.C. § 2286b(d), the Board requests a report
within 45 days of receipt of this letter that documents (1) how structural
design margins will be managed as a function of design uncertainty, and (2) how
DOE plans to systematically review the Waste Treatment Plant design to identify
and address potential problems before they manifest themselves as significant
safety issues.
Sincerely,
John T. Conway
Chairman
c:
The Honorable Jesse Hill Roberson
Mr. Roy J. Schepens
Mr. Keith A. Klein
Mr. Mark B. Whitaker, Jr.