[DOE LETTERHEAD]
OFFICE OF RIVER PROTECTION
May 2, 2003
The Honorable John T. Conway
Chairman
Defense Nuclear Facilities Safety Board
625 Indiana Avenue, NW
Suite 700
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.
Sincerely,
Manager
cc: M. B. Whitaker, DR-1
J. H. Roberson, EM-l