CHARACTERIZATION OF CORROSION PROBE COUPONS EXPOSED IN TANK 241-AN-107

C-Ring and Pin electrodes from Corrosion Probe retrieved from Tank 241-AN-107 were examined visually and by weight loss measurements. The weight loss measurements were carried out according to ASTM Method G-190. Corrosion rates estimated from the weight loss measurements indicated extremely limited corrosion with no visually observable pitting or cracking. The extremely low corrosion rates are in agreement with the results of ultrasonic examination of the primary tank wall

Double-shell tank remaining useful life estimates

The existing 28 double-shell tanks (DSTS) at Hanford are currently planned to continue operation through the year 2028 when disposal schedules show removal of waste. This schedule will place the DSTs in a service life window of 4O to 60 years depending on tank construction date and actual retirement date. This paper examines corrosion- related life-limiting conditions of DSTs and reports the results of remaining useful life models developed for estimating remaining tank life. Three models based on controllable parameters such as temperature, chemistry, and relative humidity are presented for estimates to the year in which a particular DST may receive a breach in the primary tank due to pitting in the liquid or vapor region. Pitting is believed to be the life-limiting condition for DSTs,however, the region of the most aggressive pitting (vapor space or liquid) requires further investigation. The results of the models presented suggest none of the existing DSTs should fail by through-wall pitting until well beyond scheduled retrieval in 2028. The estimates of tank breach years (the year in which a tank may be expected to breach the primary tank wall) range from 2056 for pitting corrosion in the liquid region of tank 104-AW to beyond the next millennium for several tanks in the vapor region

The solidification under zero gravity conditions of binary alloys exhibiting solid state immiscibility

The solidification behavior of gold-silicon alloys containing up to 25 at. % silicon was studied, and a mathematical model of gravity segregation during solidification was developed. A background of knowledge is provided which can be used in the design of zero gravity solidification experiments to be carried out in the 300-ft drop tower, in Aerobee rockets and in future space missions. Such experiments are needed to develop the basic scientific knowledge required for the design of economically viable space manufacturing processes. Some preliminary zero gravity experiments were carried out on a gold-25 at. % silicon alloy using the drop tower facility

Selection of replacement material for the failed surface level gauge wire in Hanford waste tanks

Surface level gauges fabricated from AISI Type 316 stainless steel (316) wire failed after only a few weeks of operation in underground storage tanks at the Hanford Site. The wire failure was determined to be due to chloride ion assisted corrosion of the 316 wire. Radiation-induced breakdown of the polyvinyl chloride (PVC) riser liners is suspected to be the primary source of the chloride ions. An extensive literature search followed by expert concurrence was undertaken to select a replacement material for the wire. Platinum (Pt){minus}20 % Iridium (Ir) alloy was selected as the replacement material from tile candidate materials, P-20% Ir, Pt-1O% Rhodium (Rh), Pt-20%Rh and Hastelloy C-22. The selection was made on the basis of the alloy`s immunity towards acidic and basic environments as well as its adequate tensile properties in the fully annealed state

Tank characterization report for single-shell tank 241-BX-111

This document summarizes the information on the historical uses, present status, and the sampling and analysis results of waste, stored in Tank 241-BX-111. This report supports the requirements of the Tri-Party Agreement Milestone M-44-ISB

Selection of ENRAF gauge wire material compatible with the Hanford waste tank environment

This document describes the selection of the wire material that will replace the 316 SS wire in the ENRAF level indicators

Corrosion monitoring of high-level waste tanks

High-level nuclear wastes are currently being stored in carbon steel tanks at the Hanford Site. The wastes are stored in both single-shell tanks (SSTs) and double-shell tanks (DSTs). The SSTs have already exceeded their design life and some of these tanks have already leaked waste into the surrounding soil. The DSTs, on the other hand, were fabricated and put into operation more recently and have not been observed to show any leakage of wastes. One of the objectives at the Hanford Site is to monitor the degradation of the DSTs with the aid of in-tank corrosion probes. Outside the nuclear industry, electrochemical and resistance corrosion probes are in common use. The application of these probes to nuclear waste storage is generally complicated by the high radiation and complexed caustic environment. This paper deals with the details of a proposed development of commercial probes to monitor corrosion of the DSTs at the Hanford Site. Once the corrosion probes are successfully developed, the technology can be applied to SSTs and also transferred to other US Department of Energy (DOE) Sites

Control of beryllium-7 in liquid lithium

Radiation fields created by the production of /sup 7/Be in lithium of the Fusion Materials Irradiation Test (FMIT) Facility can be sufficiently high to prevent contact maintenance of system components. Preliminary experiments have shown that /sup 7/Be will adhere strongly to the FMIT piping and components and a good control method for /sup 7/Be must be developed. The initial experiments have been conducted in static stainless steel capsules and a Modified Thermal Convection Loop (MTCL). The average lithium film thickness on stainless steel was found to be 11 ..mu..m in the temperature range 495/sup 0/ to 571/sup 0/K from the capsule experiments. The diffusion coefficient for /sup 7/Be in stainless steel at 543/sup 0/K was calculated to be 5.31 x 10/sup -15/ cm/sup 2//sec. The cold leg of the MTCL picked up much of the /sup 7/Be activity released into the loop. The diffusion trap, located in the cold leg of the MTCL, was ineffective in removing /sup 7/Be from lithium, at the very slow flow rates (< 3.79 x 10/sup -4/ m/sup 3//s) used in the MTCL. Pure iron has been shown to be superior to coblat and nickel as a getter material for /sup 7/Be