IAEA CRP PROJECT Applica'on of Wireless Technologies in Nuclear - - PowerPoint PPT Presentation

IAEA CRP PROJECT

Applica'on of Wireless Technologies in Nuclear Power Plant Instrumenta'on and Control Systems

Evalua'on of electromagne'c fields from wireless technologies in a nuclear plant

Mauro CAPPELLI (CSI), Vanni LOPRESTO (Secondary CSI), Silvio CECCUZZI ENEA Riccardo CECCHI, Stefano DI GENNARO University of L’Aquila Gaetano MARROCCO University of Rome Tor Vergata

IAEA CRP PROJECT

PROJECT MOTIVATION Ø Complex geometries packed with equipment and concrete or concrete/steel barriers à effect on QoS? Ø Harsh environment à effect on physical/logical channel? Effect on I&C systems ?

Inves'ga'ng individual and combined effects of wireless technologies within a nuclear environment and their feasibility of implementa'on.

Research Objec3ves:

Ø Performing a preliminary invesFgaFon on the propagaFon of electromagneFc fields from wireless technologies within a nuclear facility by numerical modelling and simulaFon. Ø For selected scenarios, analyzing possible issues related to the propagaFon of electromagneFc fields in presence of simplified barriers mimicking the real environment of a nuclear plant. Ø Providing indicaFons on how to deploy potenFal benefits of wireless technologies in a nuclear environment, evaluaFng pros/ cons and the feasibility of implementaFon.

IAEA CRP: PROJECT SCOPE

Ø Project develops over three years Ø Study addresses propagaFon issues of wireless signals from sensors deployed in a nuclear facility for monitoring process and environmental parameters (e.g. temperature, pressure, humidity, radiaFon,…) Ø Numerical modelling and electromagneFc simulaFon of the nuclear environment through a boQom-up approach § propagaFon in line of sight § propagaFon in presence of engineered barriers § propagaFon in realisFc environment (TRIGA plant) § propagaFon in presence of radioacFve environment

IAEA CRP: PROJECT OVERVIEW

IAEA CRP: PROJECT RATIONALE

The simulaFon approach

Ø Pros of simulaFon approach Ø DifficulFes in performing experimental acFviFes inside a reactor Ø Feasibility studies Ø PredicFve models Ø Modular approach Ø Readiness of results Ø Availability of realisFc CAD models Ø Possibility of customized models Ø Time and costs Ø Issues of simulaFon approach Ø Need of a correct V&V on real cases Ø ComputaFonal limitaFons Ø Choice of the best simulaFon code for the problem under invesFgaFon

Ø Need of a correct V&V on real cases Ø ComputaFonal limitaFons Ø Choice of the best simulaFon code for the problem under invesFgaFon

IAEA CRP: PROJECT RATIONALE

Issues of the simulaFon approach

IAEA CRP: PROJECT DESCRIPTION

Ø State-of-the-art review of wireless technologies and applicaFon to nuclear faciliFes and plants. Ø SelecFon of appropriate electromagneFc simulaFon tools Ø Preliminary modeling and simulaFon of wireless signals propagaFon in simplified scenarios of a nuclear environment:

§ propagaFon in line of sight § propagaFon in presence of simplified engineered barriers

1st YEAR

IAEA CRP: PROJECT DESCRIPTION

Ø Modelling of a realisFc nuclear environment (case study: ENEA TRIGA plant) Ø ElectromagneFc simulaFon in presence of complex engineered barriers and/or mulFple signals from selected wireless technologies Ø Preliminary analysis of possible issues from propagaFon of wireless signals and electromagneFc interference 2nd YEAR

IAEA CRP: PROJECT DESCRIPTION

3rd YEAR Ø Modelling and simulaFon of wireless propagaFon in presence of radioacFve environment (ionized medium) Ø Final results and criFcal analysis of proposed approach (pros/cons evaluaFon) Ø Proposal of possible soluFons and/or alternaFve approaches for future studies

IAEA CRP: PROJECT DESCRIPTION

Expected Outputs Ø Feasibility assessment on the implementaFon of wireless technologies at nuclear faciliFes for selected scenarios Ø IndicaFons for deploying potenFal benefits of wireless technologies and highlighFng potenFal snags

DONE

IAEA CRP: ROADMAP…WHERE ARE WE NOW?

ON GOING

Phase 1 | Intro

GOALS

ü IdenFfy current and emerging wireless technologies for nuclear faciliFes ü Assess and evaluate alternaFve site analysis approaches for RF planning ü Evaluate alternaFve commercial soluFons for ComputaFonal ElectromagneFcs

Wireless Sensor Applica'on Survey in Power Plants (EPRI, 2006)

“Wireless technology is ideally suited for replacement of wire and cable from instrument or control device to the data acquisi3on system, Programmable Logic Controller (PLC), Distributed Control System (DCS), or network node access

• point. With low power, small size, and

ease of circuit integraFon advantages, wireless process control signal transmission has applica3ons for installa3ons where it can reduce maintenance, and provide signaling where not previously possible or prac3cal."

Wireless technologies in nuclear faciliFes

Wireless technologies in nuclear faciliFes

Assessment of Wireless Technologies and Their Applica'on at Nuclear Facili'es, NUREG/CR-6882, 2006

“The locaFons of wireless transmiQers must be given adequate thought and planning. The desired coverage area needs to be defined and a site analysis developed. If possible, a propaga3on analysis should be conducted; at a minimum, field tests should be conducted once the wireless equipment is idenFfied.” “The wireless technology thought to be best suited to be applied in nuclear faciliFes is the digital wireless data network”

Current Wireless Deployments in NFs

ü CommunicaFon infrastructure for mobile compuFng, consisFng of redundant fiber opFc backbone connecFng wireless APs deployed throughout the facility and providing voice communicaFon using VoIP and LAN connecFvity for data applicaFons ü Wireless teledosimetry systems ü Wireless barcode scanning system for warehouse materials management ü ImplementaFons of condi'on-based maintenance (CBM) without installing costly, cable-intensive sensors. ü Wireless access to informaFon via wireless LANs for retrieval of manuals, drawings, and procedures ü RFID for tracking parts into and out of inventory.

Wireless technologies in nuclear faciliFes

“No applicaFons were found where wireless systems are being used in safety-related systems.”

Wireless standards

Wireless networks

InsFtute of Electrical and Electronics Engineers (IEEE) 802 family of standards:

IEEE 802.11 Wireless LAN (WLAN) & Mesh (Wi-Fi cerFficaFon)

802.11a, 802.11b, 802.11g, 802.11n, 802.11ac

IEEE 802.15 Wireless PAN 802.15.1 Bluetooth cerFficaFon 802.15.2 IEEE 802.15 and IEEE 802.11 coexistence 802.15.4 Low-Rate wireless PAN (e.g., ZigBee, WirelessHART, MiWi, etc.)

Maintained by the IEEE 802 LAN/MAN Standards CommiQee (LMSC) The services and protocols specified in IEEE 802 map to the Data Link and Physical layers of the ISO-OSI model.

IEEE 802 splits the Data Link Layer into two sub-layers named Logical Link Control (LLC) and Media Access Control (MAC)

802.11 Wireless LANs

Wireless LANs are covered by the IEEE 802.11 series of standards (802.11a, 802.11b

802.11g, 802.11n, 802.11ac): Wireless Fidelity (WiFi) standards.

802.11a

Band: 2.4GHz ISM band 1214 overlapping 22 MHz DSSS channels

Frequency delta: 5 MHz Throughputs: 5.9 Mbps (TCP) 7.1 Mbps (UDP) EIRP power limit: 18 dBm (63 mW)

802.11b

Wireless Sensor Networks

Vision

Wireless Low power Limited range → mulF-hop Self-organizing (Ad-hoc) Low cost

Standards: 802.15

802.15.4

802.15.4e Industrial applicaFons

802.15.1 (Bluetooth) Bluetooth LE 6LoWPAN

802.15.4 implements the lowest power consump3on protocol !!

802.15.4 PHY

Bands:

868 MHz: 1 channel, EU only 915 MHz ISM: 10 channels, US only 2.4 GHz ISM: 16 channels

Receiver sensiFvity

• 85 dBm @ 2.4 GHz
• 92 dBm @ 868/915 MHz

Typical TX power

1 mW 100 mW

AnalyFc approximaFon vs CEM

How to overcome the inability to derive closed- form soluFons of Maxwell's equaFons for complex problem?

AnalyFc approximaFon vs CEM

Analy3c Approxima3on Techniques Ease of manipulaFon Simplicity of interpretaFon Useful to infer approximate soluFons Low accuracy Computa3onal electromagne3cs (CEM) Far beQer accuracy ComputaFonally expensive Wide range of methods provides a tradeoff between accuracy and speed

Problem specificaFons

Ø 2.4 GHz single frequency signal Ø Indoor propagaFon Ø Electrically large environment

Ø About 2 orders of magnitude larger than the wavelength

Ø Different media (e.g. PEC, concrete, etc.) represenFng various structures present in the environment Ø MulFple TX antennas to be excited at the same Fme

Indoor propagaFon models vs CEM methods

1. ITU model: it esFmates the path loss inside a room or a closed area inside a building delimited by walls of any

• form. Suitable for appliances

designed for indoor use, this model approximates the total path loss an indoor link may experience: L= 20 log(f)+Nlog(d)+Pf(n)-28 2. Log-distance path loss model: radio propagaFon model predicFng the path loss a signal encounters inside a building or densely populated areas

• ver distance:

L= L0+10 γ log(d/d0)+N0 (γ and N0 must be experimentally characterized) This is not applicable to our problem because it usually refers to well-ordered indoor environment, not to a complex environment like a nuclear plant à CEM approach !!

Which CEM tool?

Full-wave techniques AsymptoFc high frequency techniques

FEKO: which solver?

Given the electrical size of the problem, asymptoFc methods seem to be the only feasible soluFon Physical OpFcs Geometrical OpFcs

Uniform Theory

• f DiffracFon

Physical OpFcs

The big picture

• PO starts with a known radiaFng current distribuFon, or the radiaFon

paQern of an antenna

• When a scaQerer is placed in the radiated field, PO uses a physical

approximaFon to compute the induced currents on the surface

• The scaQered field is obtained by numerical integraFon of the surface

currents Effects of diffracFons, mulFple bounces and creeping waves are neglected Easy to hybridize with MoM

Physical OpFcs

G= scalar free space Green’s funcFon

• Given the known incident field on a scatterer surface 𝑇
• 𝑇 is divided into lit regions and shadow regions depending on the visibility from

the incident wave direction

• High-frequency surface currents induced on 𝑇 are approximated by the so called

PO currents Ԧ 𝐾𝑄𝑃 = ቊ2ො 𝑜𝑡𝑑𝑏𝑢 × 𝐼𝑗𝑜𝑑 𝑚𝑗𝑢 𝑡ℎ𝑏𝑒𝑝𝑥

• Physical approximations:
• For lit regions Ԧ

𝐾𝑄𝑃 is an approximation of the MFIE (Magnetic Field Integral Equation), whose exact form is used by the MoM: 1 2 Ԧ 𝐾𝑇 Ԧ 𝑠 = ො 𝑜𝑡𝑑𝑏𝑢 × 𝐼𝑗𝑜𝑑 Ԧ 𝑠 + ො 𝑜× ර

𝑇

Ԧ 𝐾𝑇(Ԧ 𝑠′) × 𝛼′𝐻 Ԧ 𝑠, Ԧ 𝑠′ 𝑒𝑇 ∀Ԧ 𝑠, Ԧ 𝑠′∈𝑇

• The zero surface currents in the shadow regions neglect the creeping wave contribution

Physical OpFcs

• The scattered field 𝐹𝑡𝑑𝑏𝑢 from 𝑇 at a point Ԧ

𝑠 can be obtained explicitly by integrating the PO current: 𝐹𝑡𝑑𝑏𝑢 Ԧ 𝑠 = 𝑘𝑙𝑎0 4𝜌 ර

𝑇

෠ 𝑙 × ෠ 𝑙 × Ԧ 𝐾𝑄𝑃 𝐻 Ԧ 𝑠, Ԧ 𝑠′ 𝑒𝑇

• The numerical problems are
• Judge whether a particular part of 𝑇 is lit or shadowed
• Evaluate Ԧ

𝐾𝑄𝑃 on the meshed 𝑇

• Evaluate 𝐹𝑡𝑑𝑏𝑢 by integrating over the surface currents
• Effects of diffractions, multiple bounces and creeping waves are neglected
• PO is current based, unlike other asymptotic methods like UTD, which is

field based. This gives it enormous advantages in terms of hybridization with MoM

DirecFon poinFng from S to r

BUT: FEKO implements a number of extensions to the PO:

• Fock currents to account for the effect of creeping waves over the shadow

boundary region into "unlit" areas;

• CorrecFon terms to achieve more accurate current representaFon close to

edges and wedges. à See FEKO PO simulaFons *

Geometrical OpFcs

• Postulates
• Wavefront are locally plane and waves are TEM
• Rays are normal to the equiphase planes
• Homogeneous medium
• No spatial variation of 𝜗𝑠→Rays travel in straight lines
• Refraction obeys Snell’s law
• sin 𝜄1

sin 𝜄2 = 𝑜2 𝑜1

• Reflection obeys the Law of reflecion
• Power in a flux tube (bundle of rays) is conserved
• ׭

𝐵𝑠𝑓𝑏 1 𝑋 ∙ 𝑒Ԧ

𝑡 = ׭

𝐵𝑠𝑓𝑏 2 𝑋 ∙ 𝑒Ԧ

𝑡

ni=refracFve index

Uniform Theory of DiffracFon

• GO is only valid in lit regions, because edge diffraction gives a nonzero field in
• shadows. Edge effects are not taken into account by GO.
• The total field at Ԧ

𝑠 can be decomposed into GO and diffracted components 𝐹 Ԧ 𝑠 = 𝐹𝐻𝑃 Ԧ 𝑠 + 𝐹𝑒 Ԧ 𝑠

• UTD is an extension of the Geometrical Theory of Diffraction (Keller, 1962)
• GTD is only valid in deep shadow regions since it exhibits singular behavior near

the shadow boundary

Uniform Theory of DiffracFon

• Geometrical Theory of Diffraction
• Case of an incident ray at the diffraction point

𝑅𝐹

• Diffracted rays lie on a cone of half angle 𝛾0

(Keller cone) GTD soluFons present discon'nui'es at the shadow boundaries To predict a conFnuous total field, in 1974 Kouyoumjian and Pathak introduced UTD, mulFplying by a canonical transiFon funcFon, which is unitary inside the deep-shadow region.

Phase 2 | Intro

GOAL: evaluate the three asymptoFc solvers available in FEKO in a NLOS (Non-Line-Of- Sight) condiFon 3 experimental condi3ons

Ø PEC room Ø PEC room without sidewalls

3 setups

Ø PEC room slice

6 setups

Phase 2 | LOS vs NLOS

LOS NLOS

TX TX

NB: TX is centered on the edge of the irradiaFon plane

PEC room

DescripFon

A TX dipole is located inside a PEC room, emiPng 1W of radiated power. A wall separates the room in two halfspaces, one of which contains the

• dipole. A near field computa'on is

requested in the other half space. The wall occludes the LOS but, its width and height being slightly smaller than the room, does not cover the en're room sec'on.

TX MoM

PEC room - Results

Room: LEPO, Wall: PO * Room: PO, Wall: PO * Room: PO, Wall: PO Room: GO, Wall: GO Room: GO, Wall (concrete): GO Room: UTD, Wall: UTD Wall (concrete): PO Wall: PO

* PO/MoM decoupled

E-field on the other side of the wall vs different methods

E-field E-field

Phase 2 - Summary

Ø Environment geometry has been designed such that both diffrac3on and reflec3on play an important role, the LOS being occluded by a PEC wall; Ø Asympto3c methods give results that are more or less accurate when compared with a full-wave method, the degree of accuracy depending on the parFcular method and varying along the computed near field; Ø It is of primary importance choosing the proper numerical method for the specific problem in order to come to reasonable, reliable conclusions.

Phase 2 - Summary

Ø PO generally over-esFmates the actual power; Ø UTD generally under-esFmates the actual power; Ø Near the surface of the PEC wall, PO seems to provide a beQer accuracy. It also models some interference figures due to rays that are reflected by the ceiling and reach the other side of the PEC wall. These effects are modeled with reasonable accuracy as far as 1.5 meters away from the PEC wall; Ø UTD is able to model mul3ple reflec3ons, edge and corner diffrac3on when applied to large polygonal plate, but it is not well suited to the analysis of complex objects with curved surfaces. Accordingly, as the distance from the PEC wall increases, UTD seems to model the effects of construcFve/destrucFve interference with much more accuracy. These interference figures are not modeled by PO, whereas GO seems to capture some of them;