Experience with Soluble Neutron Poisons for Criticality Control at ICPP

Conference · Sun Nov 12 04:00:00 EST 1978

OSTI ID:6566240

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

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1. Idaho National Engineering Laboratory (INEL), 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 is 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: Idaho National Engineering Laboratory (INEL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: EY-76-C-07-1570
• OSTI ID: 6566240
• Report Number(s): CONF-781105--10
• Country of Publication: United States
• Language: English

Related Subjects

050800* -- Nuclear Fuels-- Spent Fuels Reprocessing
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BORON
CONTROL
CRITICALITY
DISSOLVERS
ELEMENTS
ENERGY SOURCES
FUEL REPROCESSING PLANTS
FUELS
GADOLINIUM
HEAD END PROCESSES
Headend Fuel reprocessing Systems
IDAHO CHEMICAL PROCESSING PLANT
METALS
NATIONAL ORGANIZATIONS
NUCLEAR FACILITIES
NUCLEAR FUELS
NUCLEAR POISONS
Nuclear Criticality Safety Program (NCSP)
RARE EARTHS
REACTOR MATERIALS
REPROCESSING
SEMIMETALS
SEPARATION PROCESSES
SOLUBLE POISONS
SPENT FUELS
Soluble Poisons
US AEC
US DOE
US ERDA
US ORGANIZATIONS