Experience with Soluble Neutron Poisons for Criticality Control at ICPP

Conference · Sun Nov 12 04:00:00 EST 1978 · Transactions of the American Nuclear Society

OSTI ID:6537630

Wilson, R. E. ^[1]; Mortimer, S. R. ^[1]

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1. Allied Chemical Corporation, Idaho Falls, ID (United States)

Soluble neutron poisons assure criticality control in two of the headend fuel reprocessing systems at the Idaho Chemical Processing Plant. Soluble poisons have been used successfully since 1964 and will be employed in the projected new headend processes. The use of soluble poisons (1) greatly increases the process output (2) allows versatility in the size of fuel assemblies processed and (3) allows the practical reprocessing of some fuels. The safety limit for all fluids entering the U-Zr alloy dissolver is 3.6 g/liter boron. To allow for possible deviations in the measurement systems and drift between analytical sampling periods, the standard practice is to use 3.85 g/liter boron as the lower limit. This dissolver has had 4000 successful hours of operation using soluble poisons. The electrolytic dissolution process depends on soluble gadolinium for criticality safety. This system is used to process high enriched uranium clad in stainless steel. Electrolytic dissolution takes advantage of the anodic corrosion that occurs when a large electrical current is passed through the fuel elements in a corrosive environment. Three control methods are used on each headend system. First, the poison is mixed according to standard operating procedures and the measurements are affirmed by the operator's supervisor. Second, the poisoned solution stirred, sampled, analyzed, and the analysis reported while still in the mix tank. Finally, a Nuclear Poison Detection System (NPDS) must show an acceptable poison concentration before the solution can be transferred. The major disadvantage of using soluble poisons is the need for very sophisticated control systems and procedures, which require extensive checkout. The need for a poisoned primary heating and cooling system means a secondary system is needed as well. Experience has shown, however, that production enhancement more than makes up for the problems.

• Research Organization: Allied Chemical Corporation, Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• OSTI ID: 6537630
• Report Number(s): CONF-7811109-
• Conference Information: Journal Name: Transactions of the American Nuclear Society Journal Volume: 30
• Country of Publication: United States
• Language: English

Related Subjects

050800* -- Nuclear Fuels-- Spent Fuels Reprocessing
054000 -- Nuclear Fuels-- Health & Safety
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
42 ENGINEERING
420203 -- Engineering-- Handling Equipment & Procedures
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
CONTROL
CRITICALITY
Control Systems and Procedures
Criticality Control
FUEL REPROCESSING PLANTS
HEAD END PROCESSES
IDAHO CHEMICAL PROCESSING PLANT
NATIONAL ORGANIZATIONS
NEUTRON ABSORBERS
NUCLEAR FACILITIES
Nuclear Criticality Safety Program (NCSP)
SAFETY
Soluble Neutron Poisons
Soluble Poisons
U-Zr Alloy
US AEC
US DOE
US ERDA
US ORGANIZATIONS