Neutron Flux Measurements of the University of California, Irvine TRIGA Mark I Reactor

and Installation of a Flow

Loop Terminus Irradiation Port

Amber Hennessy October 9, 2015 TRTR

Reactor Characteristics

• First critical: November 1969

• Max power: 250 kW

• 4 control rods • 2 transient

• 2 mechanically driven

• 82 fuel elements • ~ 20% enriched

Facility Personnel

Reactor Supervisor

George Miller

Reactor Director

A.J.

Shaka

Senior Reactor Operator

Mikael Nilsson

Reactor Operator

Tro Babikian

Reactor Operator

Michael Gray

Assistant Reactor Supervisor

Jonathan Wallick

Reactor Operator

Alex Braatz

Senior Reactor Operator

Amber Hennessy

Reactor Operator

Raul Ocampo

Reactor Operator

Leila Safavi

Reactor Operator

Randy Ngelale

Irradiation Ports

• Central Thimble (CT)

• Rotatory Specimen Rack (LS)

• Pneumatic Transfer System (PT)

• Delayed Neutron System (DNS)

• Flow Loop Terminus (FLT)

FLT

Neutron Flux Using the Cd Ratio

• Gold Irradiated with and without Cadmium • Captures most neutrons

below about 0.3 eV

• ASTM standard

𝑅𝑅 =𝐴𝐴𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐴𝐴𝐶𝐶𝐶𝐶

ϕ𝑡𝑡𝑡 =𝐴𝐴𝑠𝑠𝑁𝑁σ𝑡𝑡𝑡

∗𝑅𝑅 − 1𝑅𝑅

• A = corrected

• R = Cd ratio

• N = # molecules of target

• 𝜎𝜎 𝑡𝑡𝑡= thermal cross section

Neutron Flux Height Profiling

• ~18 cm Au/Al wires

• 0.11% Gold

• Bare and Cd Covered

• 0.35 mm thick Cd

• Irradiated at 250 kW

• 30 min.

• CT and LS

Counting Setup

• Cut into ~ 0.7 cm pieces • 27 pieces total per each

wire

• 4 wires total

• Counted standing upright • Point source to detector

Wire

Reactor Components Surrounding the core

Center of the core

Flow Loop Terminus

• Located in the G ring

• Purpose: to look at recoil effects of irradiated target matrix

Flow Loop Terminus

• Series 1 high performance meter pump

• Clear urethane tubing

• Solvent flasks

• PEEK cup and tubing

Work completed by Leila Safavi-Tehrani

41Ar Production

• Open to air hollow aluminum tube with 25° bend

• 41Ar concerns due to its presence in air

• 6 hour irradiation at 250 kW

• Measurements throughout irradiation • Opening of the sample loop

• Mixing of the air in the sample loop

Work completed by Leila Safavi-Tehrani

FLT Dose Rates

Work completed by Leila Safavi-Tehrani

Special Thanks

Jonathan Wallick

Leila Savfavi-Tehrani

George Miller

Funding Agency

Nuclear Science and Security Consortium

Thank You!

Questions?