Coupon corrosion monitoring of a high level waste tank

Radioactive nuclear waste, which was generated during the production of nuclear fuel, is safely stored in contained underground tanks and is being processed for long-term storage. A coupon corrosion rig (CCR) for monitoring was designed and used in a preliminary trial on a tank containing diluted low-level radioactive waste. Welded and standard flat coupons were exposed for ten months. The coupons were exposed in both the liquid waste and the air space above the waste. The evaluation consisted of visual examination and weight loss and pit depth measurements. Corrosion degradation was not significant for coupons in the waste. The corrosion in the air space was characterized by variable-depth degradation under adherent corrosion products. The coupon areas exposed at the air-waste interface had pits; the deepest measuring 6 mils. These results are consistent with those from previous laboratory coupon tests in simulated waste