National Nuclear Security Administration
March 13, 2000
The Honorable A. J. Eggenberger
Defense Nuclear Facilities Safety Board
625 Indiana Avenue, N.W., Suite 700
Washington, DC 20004-2901
Dear Mr. Chairman:
Ambassador Brooks has requested that I provide you additional information in response to your March 18, 2005 letter. †In two previous letters, dated May 10, 2005, and June 15, 2005, Ambassador Brooks provided you results of our survey of leaks and crack locations within the Device Assembly Facility (DAF). †In his May 16, 2005, letter, Ambassador Brooks committed to providing you a copy of our plan to repair the DAF water leaks. †A copy of this Water Leak Repair Plan is enclosed (Enclosure 1). †In addition, an assessment of the severity and significance of the observed cracks on the DAF was conducted by experts from the Bechtel National, Incorporated. †A copy of the report containing results of this assessment is also enclosed (Enclosure 2).
The Bechtel National, Incorporated experts concluded that the primary cause of the observed concrete cracking is shrinkage, and the observed shrinkage cracking is expected to have a negligible effect on the capacity of the structure. †In addition, these experts concluded that the observed concrete cracking does not affect the operability of the structure. †The Bechtel National, Incorporated report recommended an enhanced monitoring program to be implemented to further investigate any anomalous conditions observed in the future. †I am committed to implementing the report-recommended enhanced monitoring program. †This program is included as part of the Water Leak Repair Plan.
In the Ambassadorís June 15, 2005, letter to you, he described our plan for a phased approach to analyze the structural adequacy of the Device Assembly Facility safely systemsí slabs and walls with cracks 0.04 inch or wider. †In light of the results of our survey of leaks and crack locations within the DAF, and in consideration of detailed analysis provided by Bechtel concrete experts, we have concluded that further evaluation of the integrity of DAF structures will not be necessary. †I understand that the Board retained an independent concrete expert to assess the structural adequacy of the DAF. †If the results of the Boardís assessment are substantially different from the Bechtel report provided in Enclosure 2, I would appreciate a copy of the report.
As discussed in the Water Leak Repair Plan, a review of concrete test records and concrete curing conditions will be completed to ensure that the concrete used had attained the specified design strength, and is in compliance with required specifications. †If this review identifies anomalous conditions, additional actions will be identified.
We have initiated actions to execute the Seismic Analysis and Evaluation Plan that was mentioned in the Ambassadorís May 16, 2005, letter. †Currently, geotechnical site investigations are underway in support of efforts to update our understanding of seismic hazards.
I am committed to ensuring all operations within the Device Assembly Facility are conducted safely. †Our plan is to start the leak repair program in the current fiscal year, starting with repairing the roofs in the Device Assembly Facility buildings where the criticality assembly machines will be installed. †This schedule is consistent with the future programmatic needs for criticality experiments.
If you have any questions, please contact me or have your staff call Ms. Deborah D. Monette of the Nevada Site Office at (702) 295-2588.
Thomas P. DíAgostino
† for Defense Programs
L. Brooks, NA-1, w/enclosures
K. Carlson, NSO, w/o enclosures
M. Whitaker, DR-1, w/enclosures