OFFICE OF RIVER PROTECTION
May 2, 2003
The Honorable John T. Conway
Defense Nuclear Facilities Safety Board
625 Indiana Avenue, NW
Washington, D.C. 20004
Dear Mr. Chairman:
COMPLETION OF TANK INTEGRITY COMMITMENTS TO THE DEFENSE NUCLEAR FACILITIES SAFETY BOARD (DNFSB)
Reference: DOE HQ letter from C. L. Huntoon to J. T. Conway, DNFSB, Regarding Tank Integrity, dated November 30, 2000.
U.S. Department of Energy (DOE) commitments on Hanford Tank Integrity as documented in the above Reference are now complete. We propose that the DNFSB commitments from the Reference be closed. DOE completed the remaining action item by the addition of 23,600 gallons of 19 M sodium hydroxide (caustic) to Tank 241-AN-107 on April 24, 2003. This is expected to bring bulk waste to well within Hanford Tank Farms chemistry limits. Calculations based on recent core solids samples of Tank 241-AN-l 07 indicate that the added caustic should maintain tank waste chemistry in specification for approximately five years.
Post-caustic core sampling is scheduled in June 2003, which will confirm the extent of caustic mixing into the solids layer from the first addition of February 2002, as well as analyzing free hydroxide concentration in the supernate. Core sampling 12 to 18 months from the second addition will evaluate the extent of caustic mixing as compared with the mixing mechanism modeling used for Tank 241-AN-107. Your staff will be kept apprised of these results.
If you have any questions, please contact me (509) 376-6677 or, your staff may contact Dana Bryson, Tank Farms Engineering Division, (509) 372-0947.
cc: M. B. Whitaker, DR-1
J. H. Roberson, EM-l