Annular CoreResearch Reactor

Instrumentation & Control Systems

Pulse Diagnostics System Upgrade

SAND #2007-4211

TRTR Conference 17-20 September 2007

Keith Barrett, PrimeCoreDavid Clovis, Operations Staff

Robert Zaring, Engineering Support Staff

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company,for the United States Department of Energy’s National Nuclear Security Administration

under contract DE-AC04-94AL85000.

AbstractSandia National Laboratories (SNL) and PrimeCore Systems have

developed a pulse diagnostic measurement system for the SNL Annular Core Research Reactor (ACRR) based on PXI instrumentation and leveraging ZTEC ZT410PXI modular oscilloscopes. The power and flexibility of the PXI platform and the ZT410PXI 16-bit, 400 MS/sec instrument enabled SNL and PrimeCore to replace and decidedly improve an aging system based on 8-bit bench-top scopes, amplifiers, and long cable runs. The ACRR allows scientists to perform experiments and test components under extreme radiation exposure. The research reactor is used to perform in-pile experiments for radiation effects, reactor development, and safety requirements. These experiments are conducted by “pulsing” the reactor, which allows for extremely high power levels to be achieved for short periods of time. This power then decays exponentially over time.

To ultimately capture the power measurements, Self Powered Neutron Detectors (SPND) are placed just outside of the reactor core. They generate currents that are proportional to the neutron flux of the reactor, which can be related to the reactor power. The system employed by SNL and PrimeCore then amplifies and converts the current to voltage using termination resistors, a PXI current amplifier, and an external programmable current amplifier. This method allows them to capture many different ranges and conditions. Finally, the high-resolution ZTEC ZT410PXI modular oscilloscopes acquire the voltage measurements and transfer the data to a control computer for processing.

Annular Core Research Reactor500 pneumatic operations/yr380 reactor pulses/yr• Pulses: 33,000 MW peak power,

7-7.5 msec pulse width, 280-310 MJ (Safety Limit: 500 MJ, 60,000 MW)

• Steady State: Limited by license to 2.0 MW (increasing to 2.8 MW in November 2007), have run as high as 4.0 MW.

Pulse Diagnostics System Upgrade

Pulse Diagnostics System Upgrade

• Why upgrade old system?– Replace Aging system

– Upgrade Instrumentation

– Improve Resolution and Accuracy, Reduce Noise

– Improve and simplify user interface

– Provide simple system calibration

Pulse Diagnostics System Upgrade• System Output Comparison

~ 12,000 data points

~ 640,000 data points

Previous Pulse Diagnostic System

Termination Resistor

Low-RangeSPNDs

I/V & amplifier

Termination Resistor

Oscilloscope

Analog/Digital Converter & StorageDiagnostics Computer

I/V & amplifier

High-Range SPNDs

Pulse Timer Trigger

System Overview

PXI ChassisPulse DiagnosticControl Computer

Control, Processing, DataStorage

MXILink

Reactor Pool

Or...Keithley AC\DC CurrentSource(For System Calibration\Verification)

SPNDDetector(2 to 4)

LogarithmicCurrent Amplifier(2 Channels-Pulse Only)

Digitizers(6 channels)

Or...TerminationAdapter (2Channels Pulseand Steady)

Or...SPNDDetector

HighBay Rack Control Room

External Data FileArchive Computer

Area 5

External Data ViewingOn Remote Computers

EMAIL Data Files toexperimentersOr...

Current Amplifier(Steady StateOnly)

Or...SPNDDetector

Key Hardware Improvements

• Reduced Cable Run – Instrumentation is located in High Bay.– Cable run is reduced, reducing system noise and capacitance. – Fiber optic connection from instruments to computer in control

room.

• Improved Digitizers– 8 bit scope replaced by 16 bit digitizer. – Digitizer accuracy approximately 0.25% compared to >2%.– Modular Instruments, Installed spare.

• Log Amplifiers– Converts 10 na to 10 ma to .4 to 1.4 Volts– Provides even resolution across 6+ decades of range. Approximately

5000 bits\decade of resolution compared with 512 bits (in 2 separate ranges) of resolution in the old system.

Interconnect Diagram

Detector(X4)

Termination Adapter

ZTEC Digitizer Channel(X6)

CH

Detector(X4)

Log Current Amp(X2)

In Out

ZTEC Digitizer Channel(X6)

CH

50 Ohm BNC CablesRG174, 2 ft.50 Ohm BNC

Cables RG174

50 Ohm BNCCables RG174

Connections for Terminated Channels

Connections for Log Amplified Channels

Connections for Amplified Channels

Current Amplifier(X2)

ZTEC Digitizer Channel(X6)

CHDetector

(X4)

50 Ohm BNCCables RG174

50 Ohm BNC CablesRG174, 2 ft.

Calibration Interconnect Diagram

Log Current Amp(X2)

ZTEC Digitizer Channel(X6)

CH

Calibration Connections For Terminated Channels

Keithley 6221

Out

BNC Cable RG174 3 ft.

ZTEC Digitizer Channel(X6)

CH

Keithley 6221

OutTermination Adapter

Calibration Connections For Log Amplified Channels

Triax to BNC Adapter

Calibration Connections For Amplified Channels

Current Amp(X2)

ZTEC Digitizer Channel(X6)

CH

Keithley 6221

Out

BNC Cable RG174 3 ft.

Triax to BNC Adapter

BNC Cable RG174 3 ft.

Triax to BNC Adapter

PXI Instrument Layout

8 Slot PXI Chassis (standard 19 inch rack mount)

Control PCMxi-4

ZtecDig1

2 ch

ZtecDig2

2 ch

ZtecArborNI4022Amp

PXILogAmp

2 ch

MXI-4 Card

Fiber Optic Cable60 Meter PXI CHASSIS

Control ComputerPwr1

Pwr2

RS-232

2 ch

BlankorDig3

Keithley 6221 Current Source

RS232 DB-9 Null Modem Cable FromFront of PXI To Rear of Current Source

1U AIR GAP (PXI Draws Air From Bottom of Chassis)

NI4022Amp

DL- 1641(Internal Mount)

DL- 1641(Internal Mount)

Key Software Improvements

• Integrated System – Single application runs the system, processes the data,

views and manages data.– System calibration \ verification is built into the software

package.– Excel is used as a post analysis and printing tool. It is

not used for signal processing and calculation.– Predictive Calculations embedded in program.

•Source Code Control and Installation– System will be an executable program with an installation

package for recovery.– Algorithms will be “locked” with the executable. Can only be

changed with a new revision and release.

Software Flow Diagram

Welcome ScreenPDiag_WelcomeScreen.vi

Top Level ProgramProvides access to all functions

Pulse AcquisitionPDiag_Pulse Acquistion.vi

Arms System and Acquires Data for PulsesPerforms Analysis

Pulse Configuration andUser Entry

PDiag_PulseUserEntryScreen.viSet up Pulse and enter user fields

Steady State Configurationand User Entry

PDiag_SSUserEntryScreen.viSet up Steady State Run

Steady State AcquisitionPDiag_SteadyStateAcq.vi

Arms System and Acquires Data

Steady State Data ViewerPDiag_SteadyStateViewer.vi

View\Analyze Steady State Runs

Pulse Data ViewerPDiag_PulseViewer.vi

View\Analyze Pulse Runs

System ConfigurationPDiag_SystemConfig.vi

Set up instrument addresses,Cal Factors, Amplifier Config.

System CalibrationPDiag_SystemCal.vi

Performs a calibration \verification of all channels.

Data Processing Flow

Data ProcessingRoutine in ACRRPulse DiagnosticProgram and DataViewer Application

Raw Pulse.wfm

Excel Summary File

Export to CSV Files (Text)

Logic Flow for Data Processing

LabVIEW Results Screens\ Data Presentation Program

Processed.wfm

Export to Diadem

Processed.wfm

Data Viewing Methods

OPTIONAL????

Data Viewer ProgramRunning On Pulse Diag

Computer

LabVIEWRemotePanels

Data Viewing Methods

Internet ExplorerRunning on External

Computer

Use Pulse Diagnostic Machine or Network drive as a file server: The data viewerapplication can be installed on other machines and use the data files from the pulse

diagnostic computer. .

Pulse Diag Computeror Network Group Drive

Data Viewer ProgramRunning On Remote

ComputerData Files

Pulse DiagComputer

Main ProgramData Files

EMailServer

EMail Excel files to experimenters.

ExperimentersComputers

Software Design\Implementation

• Simple Architecture, Clean Program. Basic event driven interfaces with simple state machines.

• Object based data flow.• Modular programming. • Basic Documentation in

Code• Source Code Delivered to

ACRR• LabVIEW 7.1

Pulse Diagnostics System Upgrade

• Future Work– Allow for measurement in Transient Rod Withdraw

Submode.– Obtain better results for Steady-State operations

<5% Rx Power.– Procure new larger SPND, install, and configure.

End result: Pulse Diagnostics

Operational!!!

A job well done to all involved!!!

Questions???

How much did it cost?  $105K - significant cost savings in not immediately adding new larger volume SPNDs.  Plans to upgrade to a large Cad will occur after the fact and cost another $60K.How long did it take? - 4 months to become operational, testing and tweaking is still ongoing as we have time.How much regulator involvement was required? - Not much, since it's not a safety system it required little oversight. No control functions are dependant on pulse diagnostics. Our wide-range and PPS channels still control shutdowns & scrams. What is benefit to experimenters? - Dramatically improved resolution of pulse energy versus time, significantly more flexibility in processing data, and the ability to reprocess raw data from prior tests (of the new system).Data output and detector sharing flexibility? - Any detector can be aligned with any amplifier fairly easily.  Multiple choices for output, including standalone data viewer where an experimenter can reprocess the raw data from his desktop.Why is ‘pulse’ diagnostics used for ‘steady-state’ operations? - By using the same detectors we can achieve decent power trace resolution at ~5 % (120 kW) which allows for long-term plotting of SS data and associated parameters.  We expect significant improvement (i.e. able to trace power at much lower levels say 1.2 kW) with the new large Cad detector.How difficult is ‘power’ calibration for pulse detectors? - Calibration from the detector input to the PC is a simple process using a current source and the operating program.  The program controls the current source running through a prescribed routine.  Calibration of the actual pulse vs. the measured pulse is a ‘whole nother story’.  We have no idea what our pulses REALLY look like.  Input impedance is a large factor in trying to trace power from ≤ 1 kW to ~33 GW by measuring current. We "back calibrate" our pulse height based on dosimetry data of overall MJ based on theoretical pulse shapes.Can the ‘new’ system interpret ‘old’ system data? - YES.  It can also compare data over multiple runs.  We cannot reprocess old system data since the raw inputs were not saved. Are there unique features of the new system? The ability to integrate reactor energy during any part of the pulse is a built in flexibility of the new system compared to old system. Some experimenters only care about integral energy during portions of the pulse (say immediately after a circuit is energized). Are there any cost savings of the new system? The new system saves calibration costs (~$1200 per year) of old scopes.