electrical and i&c codes and inspectionilti di ( til iltt t) numark associates, inc. 37 -...

ELECTRICAL AND I&CCODES AND INSPECTION

1Numark Associates, Inc.

Day 4

7. I&C Structures, Systems and Components (SSCs) - Introduction

Structure of the I&C sessions is similar to structure of the electrical sessions.

IEEE Std 603 is a common starting point for


IEEE Std 603 is a common starting point for the hierarchy of standards.

Other applicable standards common to both I&C and electrical SSCs include IEEE Std 323, 336, 338, 344, 379, 384, 420, 497, 498, and 572.

7. I&C SSCs - Introduction

Differences (compared to electrical SSCs):

“Half-life”: I&C technologies change more rapidly

Low signal levels (e.g., 10-9 A, mA, mV); potential for


Low signal levels (e.g., 10 A, mA, mV); potential for hardware common cause failure (CCF) from electromagnetic interference (EMI)

Use of real-time software to perform safety and control functions (new failure modes & effects; potential for CCF from software bug)

More dependencies on process systems


Therefore, there is more emphasis on:

Rigorous control of the software life cycle process for digital systems


Use of diversity for defense-in-depth

Electromagnetic compatibility (EMC)

Process system characteristics


Additional standards for digital systems are used, beginning with IEEE Std 7-4.3.2,


used, beginning with IEEE Std 7 4.3.2, which supplements IEEE Std 603.


IEEE Std 7-4.3.2, IEEE Standard Criteria for Digital Computers in Safety Systems of Nuclear Power Generating Stations

Additional computer specific requirements to supplement the criteria and requirements of IEEE Std 603 are specified in IEEE Std 7-4.3.2.

Within the context of IEEE Std 7 4 3 2 the term “computer” is a


Within the context of IEEE Std 7-4.3.2, the term computer is a system that includes computer hardware, software, firmware, and interfaces.

Criteria contained in IEEE Std 7-4.3.2, in conjunction with criteria in IEEE Std 603, establish minimum functional and design requirements for computers used as components of a safety system.

IEEE Std 7-4.3.2 and subtier standards will be covered in Session 15.


Analog Systems

“Real” real-time: continuous signal flow


Can test more exhaustively

Not many surprises – failure modes and effects are usually well known


Digital Systems

Serial data processing

Cannot test exhaustively


Can have surprises; different failure modes and effects

Must use a life cycle process for software that results in sufficiently low probability of undetected, unacceptable errors

Independent verification and validation (IV&V)

Use diversity selectively to manage risk

7. I&C SSCs - Objectives

Identify the major I&C structures, systems, and typical components

P id l i f th


Provide a general overview of the purpose of these SSCs

Discuss how these SSCs relate to new reactor inspection

7. I&C SSCs

I&C Structures


I&C Systems

I&C Components

I&C Structures

Main Control Room

Instrument Rack / Cable Spread Rooms


Remote Shutdown Panel Room

Various Structures Containing Field Instruments (Containment, reactor auxiliary building, etc.)

Main Control Room: Old vs. New

Analog TechnologySwitches, meters, status lights, alarm windows

Hardwired circuits: many cables


Digital (Computer) TechnologyInteractive graphic displays: fewer devices

Smart alarms: fewer windows

Serial data processing: fewer cables

Main Control Room - Analog


Main Control Room - Digital

[From US-APWR DCD Figure 7.1-3]


Main Control Room - Digital


Main Control Room Attributes

Seismic Category I Structure

No interaction of Seismic Cat II with Cat I (“2 over 1”)

Controlled ambient temperature & humidity


Independence maintained among redundant channels / trains (IEEE Std 603, IEEE Std 379, IEEE Std 384)

No sources of high energy – relaxed separation criteria

Human Factors

Instrument Rack / Cable Spread Room Attributes

Seismic Category I Structures

No interaction of Cat II with Cat I (“2 over 1”)




Independence maintained among redundant channels / trains (IEEE Std 603, IEEE Std 379, IEEE Std 384)

No sources of high energy – relaxed separation criteria

Remote Shutdown

A remote shutdown panel is provided outside the control room as a means of achieving and


as a means of achieving and maintaining safe shutdown independent of the control room / control complex

Remote Shutdown Panel (RSP)


RSP Attributes

RSP is normally inactive and electrically isolated from the control room

RSP status is continuously monitored


RSP transfers control of circuits required for safe shutdown, and

RSP isolates the control room circuits

Remote Shutdown Panel (RSP)

[US-APWR DCD Figure 7.4-2: Cable routing to the Remote Shutdown Room]


MCR Isolation - Testing


I&C Field Areas (Typical)

Containment – 10 CFR 50.49 EQ for LOCA / MSLB

Containment electrical penetration area – Nuclear instrumentation preamplifiers

Reactor Aux Bldg – 10 CFR 50.49 EQ for HELB and dose from post-LOCA recirculating fluids; “shine” from penetrations; also consider effects of airborne particulate


penetrations; also consider effects of airborne particulatespurious actuation of sensitive process radiation monitor)

Main steam isolation valve and main steam line areas

Remote I/O areas (switchgear, various process areas, etc., where data is acquired or outputs provided)

Student ActivityCritical Attributes Matrix


I&C Structures: Critical Attributes

Structure Critical Attribute(s)

Main Control Room


Instrument Rack / Cable Spread Room

Remote Shutdown Panel

Various Field Areas

I&C Systems


I&C Systems

Safety (Protection) Systems (Class 1E): Reactor Trip and ESF Actuation

Safe Shutdown Systems (remote shutdown capability using safe shutdown systems was previously discussed)

Information and Control Systems:


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- Information Systems Important to Safety (e.g., RGs 1.97, 1.47)

- Interlock Systems Important to Safety (e.g., Accum. MOVs)

- Control Systems (non-Class 1E) & Potential for Interaction with Safety System

I&C Systems

Diverse Systems

- ATWS (non-Class 1E reactor trip for AOOs using diverse variables and hardware)


using diverse variables and hardware)

- Diverse actuation system as defense-in-depth, in the event there is a CCF of the I&C Safety Systems software; reactor trip and selected ESF functions

I&C Systems

Data Communication Systems (DCS)

Supports communication for safety and


- Supports communication for safety and non-safety systems

I&C Systems: Safety Systems

Reactor Trip System


Engineered Safety Features Actuation System (ESFAS)

Reactor Trip System - Functions

Sense: Sense / measure variables used for reactor trip, such as neutron flux; rod position; RCS, main steam, / and feedwater thermal/hydraulic variables


Condition/Compute: Condition/process the sensed variables; calculate derived values such as DNB, kW/ft, etc.

Command: Compare value to setpoints, apply decision and voting logic

Execute: Trip/scram reactor

Reactor Trip System - Example


Reactor Trip System - Attributes

Single Failure Criterion (IEEE Std 379):

The safety systems shall perform all required safety functions for a design basis event in the presence of the following:

a) Any single detectable failure within the safety systems concurrent with all identifiable, but non-detectable failures


b) All failures caused by the single failure

c) All failures and spurious system actions that cause, or are caused by, the design basis event requiring the safety function

The single failure could occur prior to, or at any time during, the design basis event for which the safety system is required to function.


Single Failure Criterion (IEEE Std 379 –nondetectable failures):

Detectable failures: Failures that can be identified through periodic testing or that can be revealed by alarm or anomalous indication. Component failures that are detected

t th h l di i i t l l d t t bl


at the channel, division, or system level are detectable failures.

NOTE: Identifiable, but nondetectable failures are failures identified by analysis that cannot be detected through periodic testing or revealed by alarm or anomalous indication.


Single Failure Criterion (IEEE Std 379 –nondetectable failures):

When nondetectable failures are identified, one of the following courses of action shall be taken:


Preferred course: The system or the test scheme shall be redesigned to make the failure detectable.

Alternative course: When analyzing the effect of each single failure, all identified nondetectable failures shall be assumed to have occurred.


Independence (IEEE Stds 603, 384, 7-4.3.2)

- Separation (IEEE Std 384)

- Electrical Isolation (IEEE Std 384)

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- Isolation Devices (optical, coil-contact, etc.)are considered part of the Class 1E system and must be qualified, usually by laboratory test

- Input (Class 1E) and output (non-1E) wiring to the isolation device must be separated IAW IEEE Std 384

- Data Isolation - IEEE Std 7-4.3.2


Testing and Calibration (IEEE Std 603 / IEEE Std 338)

Capability for testing and calibration of safety system equipment shall be provided while retaining the capability of the safety systems to accomplish their safety functions.

The capability for testing and calibration of safety system


The capability for testing and calibration of safety system equipment shall be provided during power operation and shall duplicate, as closely as practicable, performance of the safety function.

Testing of Class 1E systems shall be in accordance with the requirements of IEEE Std 338-1987.


Indication of Bypasses (IEEE Std 603; see also RG 1.47))

If the protective actions of some part of a safety system have been bypassed or deliberately rendered inoperative for any purpose other than an operating bypass, continued indication of this fact for each affected safety group shall be provided in the control room.

(a) This display instrumentation need not be part of the safety systems.


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(b) This indication shall be automatically actuated if the bypass or inoperative condition is expected to occur more frequently than once a year, and is expected to occur when the affected system is required to be operable.

(c) The capability shall exist in the control room to manually activate this display indication.


Reliability (IEEE Stds 603, 352, 577, 7-4.3.2)

For those systems for which either quantitative or qualitative reliability goals have been established, appropriate analysis of the design shall be performed in order to confirm that such goals have been achieved [IEEE Std 603]


have been achieved [IEEE Std 603].

IEEE Std 352 and IEEE Std 577 provide guidance for reliability analysis.

IEEE Std 7-4.3.2 provides guidance on the application of these criteria for safety system equipment employing digital computers and programs or firmware.

ESFAS - Functions

Sense: RCS and Steam/feedwater T/H variables, et al

Condition/Compute: Condition/process the sensed variables; calculate derived values


sensed variables; calculate derived values

Command: Compare to setpoints, perform ESF initiation and voting logic

Execute: Initiate ESF systems/components such as ECCS, EFW, containment isolation, et al

ESFAS - Attributes

ESFAS attributes are similar to reactor trip system attributes

However, there are some additional


considerations:

- Safety consequences of unintended initiation

ESFAS - Attributes

Potential for system actuation due to single failure (IEEE Std 379):

The potential for system actuation due to single failure shall be examined to determine whether such actuation will constitute an event with unacceptable safety consequences


event with unacceptable safety consequences.

For any such actuation thus identified as being unacceptable, the single-failure criterion shall be met (i.e., the safety systems must not initiate the actuation as a result of any single detectable failure in addition to all nondetectable failures in the systems).

I&C Systems -Information and Control

Information Systems Important to Safety

Interlock Systems Important to Safety



Control Systems not Required for Safety

Control / Protection Interaction

I&C Systems -Communication and Diversity

Data Communication Systems


Use of Diversity to Preclude CCF


Bypass and Inoperable Status Indication (RG 1.47)


Accident Monitoring Instrumentation

(RG 1.97/IEEE-497)

Information Systems Important to Safety – RG 1.47

Selected RG 1.47 Guidance:

Provide indication system that automatically indicates, for each affected safety system or subsystem, the bypass or deliberately induced inoperability of a safety function and the systems actuated or controlled by the safety function.


The indicating system should be activated automatically by the bypassing or the deliberately induced inoperability of any auxiliary or supporting system that effectively bypasses or renders inoperable a safety function and the systems actuated or controlled by the safety function.


Bypass and inoperable status indicators should be designed and installed in a manner that precludes the possibility of adverse effects on plant safety systems.


The indication system should not be used to perform functions that are essential to safety, unless it is designed in conformance with criteria established for safety systems.


Operating bypass*: Inhibition of the capability to accomplish a safety function that could otherwise occur in response to a particular set of generating conditions.


Different modes of plant operation may necessitate an automatic or manual bypass of a safety function. Operating bypasses are used to permit mode changes (e.g., prevention of initiation of ECCS during cold shutdown mode). *IEEE Std 603


Maintenance bypass*: Removal of the capability of a channel, component, or piece of equipment to perform a protective action due to a requirement for replacement, repair, test, or calibration.


Not the same as an operating bypass. A maintenance bypass may reduce the degree of redundancy of equipment, but it does not result in the loss of a safety function.

*IEEE Std 603


Accident Monitoring Instrumentation (RG 1.97 / IEEE Std 497)

Design and qualification requirements for accident


gmonitoring instrumentation depend on the use of the instrument for accident monitoring (RG 1.97 Type A, B, C, D, and/or E)

The design and qualification can range from Class 1E to commercial grade.


Accident Monitoring Instrumentation

Type A - Necessary manual actions

Type B - Accomplishment of safety functions


Type B Accomplishment of safety functions

Type C - Potential for breach of barrier

Type D - Operation of individual safety systems

Type E - Release of radioactive materials

Interlock Systems Important to Safety - Examples

Valve Interlocks:

- ECCS accumulator outlet MOVs


- RCS / RHR isolation MOVs

Nuclear Instrumentation: Operating Bypass

Control Systems Not Required for Safety

Accident analysis does not take credit for control system actions

Examples:- Pressurizer pressure control


- Steam generator level control- Rod control

Potential for unacceptable interaction of control system with protection system must be analyzed (IEEE Std 603)


IEEE Std 603, Section 6.3.1

Where a single credible event can cause a non-safety system action that results in a condition requiring protective action, andcan concurrently prevent the protective action designated to provide principal protection against the condition, one of the following requirements shall be met:


following requirements shall be met:

(a) Alternate channels satisfying certain IEEE Std 603 requirements [explained later] can be provided, or:

(b) Equipment not subject to failure caused by the same single credible event shall be provided to detect the event and limit the consequences to a value specified by the design bases. Such equipment is considered a part of the safety system.


IEEE Std 603, Section 6.3.1: Requirements for “Alternate channels”:

Alternate channels not subject to failure resulting from the same single event shall be provided to limit the consequences of this event to a value specified by the design basis. Alternate channels shall be selected from the following:


channels shall be selected from the following:

- Channels that sense a set of variables different from the principal channels

- Channels that use equipment different from that of the principal channels to sense the same variable

- Channels that sense a set of variables different from those of the principal channels using equipment different from that of the principal channels


Data Communication:

A method of sharing information between devices that involves a set of rules,


,formats, encodings, specifications, and conventions for transmitting data over a communication path, known as a protocol.


Computer-based safety systems use DCS to communicate:

Divisionally, with input and output devices in each division (Remote I/O)


Across and among redundant divisions, for voting logic (isolated)To control systems (isolated)To display and information systems (isolated for non-safety displays / info systems)

Data Communication Systems (DCS) Attributes

Where safety related, the DCS must satisfy the same criteria as for an analog system:

- Quality / Qualification


- Single Failure Criterion- Independence- Reliability- Testability- Diversity- etc.

Data Communication Systems (DCS) Attributes

However, the DCS has additional considerations relative to analog communication:

EMI

Time coherency of data (sequence of data packets)


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Error detection and recovery

Safety system timing must be deterministic or bounded

Data isolation (e.g., data from safety system is read-only to control system)

Protocols: minimize unneeded functions and complication


Typical DCS Configurations: Remote I/O

Analog instruments provide signals (4-20 mA, 1-5 Vdc, contact closure, etc.) to data acquisition units (remote I/O) in plant process areas


A/D conversion of signals in remote I/O unit

Digital data is then multiplexed (signals shared over wire or fiber-optic cable) to protection or control systems

Protection or control systems can provide outputs to remote I/O units to open valves, start / stop pumps, etc., as prescribed by the control logic


Following is a typical example of a plant wide DCS (US EPR) and


plant-wide DCS (US-EPR) and Protection System

DCS Symbols (Typical)


Defense-in-Depth: Example


DCS Independence


DCS and Safety System Diversity



I&C Systems


I&C Systems

I&C Systems Critical Attributes

I&C System Critical Attribute(s)

Reactor Trip

ESFAS

Remote Shutdown


Remote Shutdown

Information (Safety)

Interlocks (Safety)

Control (Non Safety)

Data Communication

Diversity

I&C Components


I&C Components

Sensors and Signal Conditioners

A l / Di i l C (ADC )


Analog / Digital Converters (ADCs)

Bistables (analog comparators)

I&C Components

Displays and Alarms

- Video screen displaysDedicated meters bargraphs etc


- Dedicated meters, bargraphs, etc.- Dedicated status lights- Alarm panels / alarm conditioning

I&C Components: Sensors

Nuclear instruments

Process instruments- Temperature


- Pressure- Flow- Level

- Position

Nuclear Instruments

Excore Neutron Flux DetectorsSource range

Intermediate range


Intermediate range

Power range

Incore DetectorsMovableFixed

Nuclear Instrumentation - Excore


Fission Chamber (W)


Excore Detector (Gamma-Metrics)


Incore Detector System - W Moveable


Incore Detector System – Fixed

Self-Powered Neutron Detectors (SPNDs)

• Platinum emitter produces current proportional to neutron flux

• Need no power supply• Simple and robust structure


• Simple and robust structure• Relatively small size for in-core installation• Good temperature/pressure stability • Compensation for background noise required (for some

emitters)• Delayed signal response (for some emitters)

Nuclear Instrumentation - Excore: Attributes

IEEE Std 603 and supporting standards, including IEEE Stds 323, 336, 338, 344, 379, 384, 420, 497, 498, 572, etc.


Triax cable / connectors for EMC purposes

Baseline Time Domain Reflectometry (TDR) for NI cables

Temperature Sensors

Resistive Temperature Detectors (RTDs)

Process and component temperatures


Thermocouples

Core exit temperatures

Temperature Sensors: RTD

RTD probe & head (Conax)



RTD (resistive temperature detector)

Resistance varies with temperature

Typically mounted in thermowell


Typically mounted in thermowell

Resistance can be measured with a bridge circuit, which produces a voltage signal

Temperature Sensors: RTD – 2 Wire


Temperature Sensors: RCS RTDs


Temperature Sensors:

RTDs – Potential Problems

Process temperature stratification / “swirling”Cracked thermowellIntrusion of chemicals from connection head into thermowell Cracked or open sensing element Thi i f th RTD l ti i f h i l ti


Thinning of the RTD platinum wire from chemical reactionWrong calibration tables (configuration control)Inadequate dynamic response Failure of extension lead wires Low insulation resistance between RTD lead and groundLoose or bad connections.Imbalance in lead wire resistance.

Temperature Sensors: T/Cs


Temperature Sensors: T/Cs – Potential Problems

Cable/connector problems

EMI from incorrect grounding / multiple grounds / routing


Reverse connection

Long-term degradation of response time from aging

Temperature Sensors: Attributes

RTDs

IEEE Std 603 and supporting standards, including IEEE Stds 323, 336, 338, 344, 379, 384, 420, 497, 498, 572, etc., if safety related


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Shielded / twisted quad wiring

Single point ground

Loop current step response (LCSR) test


For RTDs used as protection system inputs (e.g., Thot, Tcold), the installation of a calibrated RTD should include a test procedure to demonstrate the response time applicability of the laboratory test results.

Loop current step response (LCSR) testing is an acceptable way to


Loop current step response (LCSR) testing is an acceptable way to verify that the conditions of the installed RTD are adequately correlated to the laboratory test data.

Response time testing of the installed RTDs using LCSR should use an analytical technique such as the LCSR transformation identified in NUREG-0809, “Review of Resistance Temperature Detector Time Response Characteristics,” to correlate the in-situ results with the results of a laboratory-type temperature test.


Core Exit Thermocouples

IEEE Std 603 and supporting standards, including IEEE Std 323, 336, 338, 344, 379, 384, 420, 497, 498, 572, etc.


Type K (Chromel-Alumel) is typical for core exit temperatures

Shielded / twisted pair, single point ground

Mineral insulated (MI) cable for harsh environment

Pressure Sensors


Pressure Sensors: Attributes

Proper slope and configuration of sensing (impulse) line


Static head correction

Pulsation dampeners

Freeze protection

Flow Sensors – DP Type

A Orifice

B Venturi

C Flow nozzle


D Pitot Tube (velocity head)

E Elbow Taps

Flow Measurement Regimes


Flow Sensors – Orifice


Flow Sensors – Pitot Taps

Pitot tubeVelocity head

Impact port (upstream)

Static (stagnant) port (downstream)


Static (stagnant) port (downstream)

Commonly used for airflow

Annubar™ uses Pitot principle, reconfigured using multiple impact ports

Sometimes used for raw service water

Like Pitot tube, can plug up

Flow Sensors – DP Sensing Line Issues / Features

Leaks

Trapped gas in liquid lines

Liquid in gas lines

Diff i l / d i i


Differential temperatures / densities

Tube track / seismic supports

Thermal expansion loops

Flow Sensors – DP Sensing Line Installation


Flow Sensors – DP Sensing Line Issues

For liquid, slope sensing (impulse) lines at least 1 inch per foot upward from the transmitter toward the process connection

For gas / steam, slope sensing lines downward from the transmitter toward the process connection


p

Avoid high points in liquid lines and low points in gas lines

Both sensing legs should be at the same temperature

Vent all gas from liquid sensing lines

Flow Sensors – DP Sensing Line Issues

When using a sealing fluid (e.g., steam service), fill both legs to the same level.Corrosive or hot process material should not make direct contact with the sensor module and flanges.Prevent sediment deposits in the impulse piping (tap li id f th id f th i t / t f th


liquids from the side of the pipe; tap gas / steam from the top or side of the pipe).Plug and seal unused conduit connections on the transmitter housing to avoid moisture accumulation in the terminal side.For harsh EQ environments, qualified environmental seals are required.

RG 1.151 / ISA 62.02.01 – Sensing Lines

RG 1.151 accepts the recommendations of ISA 62.01.02, Nuclear Safety-Related Instrument Sensing Line Piping and Tubing Standard for Use in Nuclear Power Plants with exceptions and clarifications;


Plants, with exceptions and clarifications; sampling lines are not included in the RG basis.

Selected (highlights) guidance follows


A single process pipe tap to connect process signals to redundant instruments should not be used.

If a single process connection cannot be avoided, justification shall be provided to permit its use. J tifi ti h ll dd th d ff t f


Justification shall address the common mode effects of both plugging and breakage.

Instrument-sensing lines shall be routed such that no single failure can cause the failure of more than one redundant sensing line unless it can be demonstrated that the protective function is still accomplished.


In hostile areas subject to high-energy jet stream, missiles, and pipe whip, the routing of redundant sensing lines shall be documented with analysis or calculations as necessary to prove that the routing protects the redundant sensing lines from failure due to


a common cause.

Instrument-sensing lines shall be run along walls, columns, or ceilings whenever practical, avoiding open or exposed areas, to decrease the likelihood of persons supporting themselves on the lines or of damage to the sensing lines by pipe whip, missiles, jet forces, or falling objects.


Routing of the nuclear safety-related sensing lines, except capillary lines, shall ensure that the function of these lines is not affected by the entrapment of gas (liquid-sensing lines) or liquid (gas-sensing lines).


( q g ) q (g g )New designs and redesigns should consider instrument location early in the design process to eliminate the need for high point vents or low point drains while maintaining sensing line slope.


Where adequate slope requirements cannot be maintained and it is not feasible to relocate the instrument so that adequate slope can be maintained, a high point vent for liquid measurement or a low point drain for gas measurement should be provided to ensure that all trapped gas or liquid can be purged from the sensing line.


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Potential inaccuracies in water level indication during and after rapid depressurization events have been identified as industry concerns and shall be considered. Inaccuracies result from noncondensable gases collecting in the condensate pot (chamber) of instrument reference legs and migrating down the reference leg.

Differential Pressure (DP) Cell


Flow Sensors – Other Types

Ultrasonic (clamp-on for testing)

Magnetic (boric acid)


Flow Sensors – Ultrasonic (Panametrics)


Flow Sensors – Magnetic


Flow Measurement: Attributes

Sufficient upstream and downstream unobstructed straight run for repeatable flow conditions (head type and ultrasonic)

Primary element accuracy


Proper configuration / slope of impulse lines

Temperature (density) correction for operation at substantially higher temperature (e.g., measured RHR flow used for acceptance test )

Pulsation dampeners – possible effect on measurement

Flow Measurement: References*

ASME Fluid Meters

Liptak, Bela G., Instrument Engineers Handbook, Chilton Book Co.


ISA 67.04 Part 2

* These can be useful technical references, but they do not necessarily represent NRC regulatory requirements or guidance, or licensing commitments.

Level Instrumentation


Level Instrumentation (dp) – Vented Vessel


Level Instrumentation (dp) – Closed Vessel


Level Instrumentation (dp) – Closed Vessel – Steam


Level Measurement: Attributes

Closed vs. vented vessel

Effect of reference leg heatup

Configuration of condensing chambers (“pots”)

Effect of vortexing


Effect of velocity head at dp tap in pipe (rather than vessel tap)

Heat tracing

Non-condensable gases in reference leg (e.g., VCT level)

Position Indication

Valve position (open/close)Stem actuated limit switch

Typical for air operated valves


Gear actuated limit switchTypical for motor operated valves

Used for status lights and interlocks

A/D Converter


A/D Converter (ADC)


A/D Converter


A/D Converter - Attributes

Relative accuracy

Conversion time

Linearity


Power supply sensitivity

Temperature coefficients

Sampling rate



I&C Components

I&C Components Critical Attributes

Component Critical Attribute(s)

Sensors


Signal Conditioning

A/D Converters

Bistables / Comparators

Displays and Alarms

I&C Components: Sensors

Nuclear instruments

Process instruments- Temperature


- Pressure- Flow- Level

- Position

7. I&C Structures, Systems and Components Objectives Review

Identified the major I&C structures, systems, and components


Provided a general overview of the purpose of these SSCs

Discussed how these SSCs relate to new reactor inspection

QUESTIONS ?


electrical and i&c codes and inspectionilti di ( til iltt t) numark associates, inc. 37 -...

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