HWVP feed preparation chemistry for an NCAW simulant, fiscal year 1992: Evaluation of offgas generation and ammonia formation

Technical Report · Wed Mar 01 00:00:00 EST 1995

OSTI ID:61080

Smith, H D; Wiemers, K D; Langowski, M H; Matheson, J D; Merz, M D; Powell, M R; Larson, D E

The Hanford Waste Vitrification Plant (HWVP) was being designed for the US Department of Energy (DOE) to immobilize high-level and transuranic wastes as glass for permanent disposal. Pacific Northwest Laboratory (PNL) supported the HWVP design activities by conducting laboratory-scale studies using an HWVP simulated waste slurry. PNL collected and evaluated data to provide a basis for predicting the HWVP feed processing chemistry as a function of feed composition and operation variables, recommending criteria for chemical adjustments, and providing guidelines with respect to important control parameters to consider during routine and upset plant operation. Conditions that affect the slurry processing chemistry were evaluated in terms of processing conditions, offgas compositions and peak generation rates, and changes in slurry compositions. A standard offgas profile defined in terms of three reaction phases, decomposition of H{sub 2}CO{sub 3}, destruction of NO{sub 2}{sup {minus}} and production of H{sub 2} and NH{sub 3}, was used as a baseline against which changes were evaluated. The test variables included NO{sub 2} concentration, acid neutralization capacity, process temperature, HCOOH addition rate, and the presence of selected process-related organics and a processed slurry (heel). Results indicate that pH is an important parameter influencing the N{sub 2}O/NO{sub x} generation ratio; NO{sub 2}{sup {minus}} can both inhibit and activate rhodium as a catalyst for HCOOH decomposition to CO{sub 2} and H{sub 2}; and the presence of a process ``heel`` appears to accelerate the formation of a separate reduced-metal phase. Temperature was observed to strongly influence the H{sub 2} generation rate. The process chemistry described in this document provides a preliminary bases for predicting the behavior of alternative feed streams and process steps applicable to future generation vitrification plants.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 61080
• Report Number(s): PNL-10369; ON: DE95010774; TRN: AHC29516%%15
• Resource Relation: Other Information: PBD: Mar 1995
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
RADIOACTIVE WASTE FACILITIES
CHEMICAL ENGINEERING
HIGH-LEVEL RADIOACTIVE WASTES
VITRIFICATION
ALPHA-BEARING WASTES
HANFORD RESERVATION
FORECASTING
EXHAUST GASES
CARBONIC ACID
NITRITES
HYDROGEN
AMMONIA
PH VALUE
NITROGEN OXIDES
SIMULATION
FORMIC ACID
PARAMETRIC ANALYSIS
ACID NEUTRALIZING CAPACITY
EXPERIMENTAL DATA