Task 3: Core Instrumentation Planning and Benchmarking

Transcription

1 MIT NUCLEAR REACTOR LABORATORY an MIT Interdepartmental Center Task 3: Core Instrumentation Planning and Benchmarking Lin-wen Hu, David Carpenter, Kaichao Sun Nov. 2-3, 2016 TREAT IRP Biannual Mee<ng, MIT

2 Task 3 Overview Ø Instrumentation Plan o Identify TREAT core monitoring needs o Select sensors and requirements o Develop instrumentation plan Ø Benchmarking o Design and testing of in-reactor instrumentation o Modeling (performance and safety) o Validation experiments Steady-state and transient tests o Analyze data and develop instrumentation report 2

3 Instrumentation Plan Ø Draft of Plan completed next step to get feedback from INL Ø Review of instrumentation layout and types: o Neutron flux, o Thermal power, o In-core temperatures. Ø Suggesting new types of sensors o Miniaturized sensors for in-core locations o Improved fidelity over critical power ranges o Higher spatial resolution Ø Calibration and readiness 3

4 TREAT Instrumentation Ø Operational reactor power measurements use radial instrumentation ports o Terminate outside of permanent graphite reflector o Ion chambers and proportional counts for neutron flux Ø In-core thermocouple-instrumented assemblies for assembly clad, reflector, and fuel block temperatures Ø Calibration of neutron detectors to reactor power uses steady-state power ~80 kw, o Heat balance with air- cooling system, o Requires extrapolation to higher power 14 6 Radial Instrumenta3on Ports INL/EXT

5 Startup Testing and Calibration Ø During TREAT physics testing fission chambers were positioned within the core (coolant channels and element centers) Ø Fission chambers, activation foils, and thermocouples moved to various radial and axial positions o Drive system mounted on reactor top shield to move detectors and foils o Core configuration dependent ANL Ø Measurement of vital parameters o Temp and flux profile o Reactivity coefficients o Detector power calibration o Neutron spectrum o Transient response INL/EXT

6 Updating Instrumentation MPFD design (Unruh, 2012) Photonis FC probes Thermocoax SPD Ø TREAT updating ion chambers in-place Ø Advanced ion/fission chamber technology o Micro-Pocket Fission Detectors for local measurement of neutron flux spectrum differentiation o Gas-filled cylindrical FC probes (e.g. CEA) o Self-powered detectors sensitive to neutron or gamma flux rapid response SPND tested in TREAT previously Ø Temperature measurement o Traditional thermocouples reliable for most point measurements o IR pyrometry can evaluate surfaces o Fiber-optic measurement (temperature or strain) possible to interrogate multiple locations along a single fiber 6

7 MITR Experiment Plan Ø Instrumenta<on Plan DraD Completed (FY16) o Instrumenta<on assembly for in- pile tests to be designed Ongoing (04/2017) Ø Experiment Loca<ons and Transient Selec<ons Completed (FY16) o Total of 6 in- core loca<ons o 2 types of transient Ø Reactor Safety Analysis for Proposed Transients Ongoing o Transient analysis using PARET/ANL (fixed inlet temperature) Completed o MITR RELAP5 system model valida<on for steady- state Ongoing (11/2016) o Transient analysis using RELAP5 To be done (12/2016) o MITR Safeguards CommiYee Mee<ng (12/2016) o Reactor experiment approval (03/2017) Ø Safety Evalua<on Report (SER) for MITR Experiments (06/2017) Ø Performing Instrumenta<on Test Experiments at MITR (07/2017) 7

8 Experiment Locations 1. Total of 6 Projected Loca3ons: Ø 2 A- ring (innermost ring) posi3ons Ø 1 B- ring (middle ring) posi3on Ø 2 axial loca3ons at each posi3on for different fast- to- thermal ra3os Ø 2 out of 6 loca3ons run transients Distance to Core Center (cm) Thermal Flux (<1 ev) Fast Flux (> 0.1MeV) Total Flux (full energy range) E E E E E E E+14 Neutron Flux (n/cm 2 /s) v Static measurements / calibrations will be performed at all 6 locations. v Transient tests will be performed for A-1 Higher and B-3 Lower for small and large fast-to-thermal ratios, respectively. 8

9 Experiment Test Plan 2. Sta3c Measurements (6): Ø The MITR operates at steady power of 60 kw (LSSS at 100 kw) with top lid open and natural convec3on mode. Ø Different in- core and ex- core posi3ons could be used for instrument test. Unit: n/cm 2 /s Thermal Flux (< 1 ev) Fast Flux (> 0.1 MeV) Total Flux MITR at 100 kw 6.17E E E+12 MITR at 6 MW 3.70E E E+14 TREAT at 100 kw 5.79E E E Slow Posi3ve Transient (2): Ø Withdrawing Regula3ng Rod (~ 200 mβ worth) to create a posi3ve period more than 50 s (LSSS at 7 s). Ø Steady power levels prior and a[er the transient are planned to be 600 W and 60 kw (LSSS at 100 kw). TREAT peaks at 18,000 MW 1.04E E E Fast Nega3ve Transient (2): Ø Using Shim Blade Drop and Scram to create nega3ve period less than 0.5 s. Ø Steady power levels prior the transient is planned to be 60 kw. 9

10 Instrument Calibration Ø Pre-irradiation testing o Sealed gamma and neutron sources o Spectrum-characterized beamlines Ø Neutron Activation Analysis Lab o Gold, Fe, 304 foils and wires for fluence o Cadmium ratio Ø Verify instrument response curves Ø Calibration requirements part of instrumentation plan Mul3- sensor Beamline NAA Lab Exis3ng calibrated instruments for rad work 10