ML20151V899

Reg Guide 1.151, Instrument Sensing Lines

ML20151V899
Person / Time
Issue date:	07/31/1983
From:	NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:
References
TASK-IC-126-5, TASK-RE REGGD-01.151, REGGD-1.151, NUDOCS 8808230051
Download: ML20151V899 (4)

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[pKfo U.S. NUCLEAR REGULATORY COMMISSION July 1983 j@ REGULATORY GUIDE

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OFFICE OF NUCLEAR REGULATORY RESEARCH

'v REGULATORY GUIDE 1.151 (Task IC 126-5)

INSTRUMENT SENSING LINES A. INTRODUCTION Any guidance in this document related to information activities has been cleared under OMB Clearance No. 3150-Section 50.34, "Contents of Applications; Technical 0011.

Information," of 10 CFR Part 50, "Domestic Licensing of Production and Utilization Facilities," requires, in part, B. DISCUSSION that design criteria be established for structures, systen.s, and components important to safety that will provide ISA 567.02, "Nuclear Safety Related Instrument Sens-reasonable assurance that the facility can be operated ing line Piping and Tubing Standards for Use in Nuclear without undue risk to the health and safety of the public.

Power "ants,"' was prepared by Committee SP67-02 of Criterion 1, "Quality Standards and Records," of Appen-the Instrument Society of America (ISA). It was approved dix A, "General Design Criteria for Nuclear Power Plants,"

by the ISA Neclear Power Plant Standards Committee on to 10 CFR Part 50 requires,in part, that structures, systems.

October 19,1978, and subsequently by the ISA Standards and components be erected (installed) to quality standards and Practices Board in June 1980. The standard provides commensurate with the importance of the safety functions design, pbysical protection, and installation requirements to be performed. Criterion 13, "Instrumentation and for instrument sensing line piping ad tubing for nuclear Control," of Appendix A to 10 CFR Part 50 requires, in poler plant applications, it est, olishes the applicable part, that instrumentation be provided to ensure adequate ASME code requirements and boundaries for the design and G safety. Criterion 24, "Separation of Protection and Control installation of instrument sensing lines that interconnect i Systems," of Appendix A to 10 CFR Part 50 and Section safety-related piping and vessels with safety-related instru-4.7.3, "Single Random Failure," of IEEE Std 279 1971 mentation and non safety-related instrumentation.

require,in part, that the interconnection of the protection and control systems be limited so as to ensure that safety is C. REGULATORY POSITION not significantly impaired, ne requirements of ISA-S67.02, "Nuclear Safety.

This regulatory guide describes a method acceptable to Related Instrument Sensing Une Piping and Tubing Stan-the NRC staff for complying with the Commission's regu-dards for Use in Nuclear Power Plants," 1980, provide lations with regard to the design and installation of safety-a basis acceptable to the NRC staff for the design and related instrument sensing lines in nuclear power plants.

Installation of safety-related instrument sensing lines in ne term "safety-related" refers to those structures, nuclear power plants sub.iect to the following:

systems, and components necessary to ensure (1)the integrity of the reactor coolant pressure boundary,(2) the

1. De requirements for instrument sensing lines in capability to shut down the reactor and maintain it in a safe Section 4.1 of ISA S67.02 should be supplemented with shutdown condition, or (3) the capability to prevent or the following:

mitigate the consequences of accidents that could result in potential offsite exposures comparable to the guideline A single instrument sensing line should not be used to exposures of 10 CFR Part 100, perform both a safety-related function and a non-safety-related function unless it can be shown that:

De Aavisory Committee on Reactor Safeguards has e

been consulted concerning this guide and has concurred in g fg,',*g g,a%eg m segumen gergot meg he the regulatory position.

North Carohna 27709.

USNRC REGULATORY GUIDES Comments should be sent to the secretary of the Commission, U.S.

Nuclear R e gulat ory Commission D.C. 20 s s S.

Attentioni Docket 6mg and Servlce E4 ranch, Washington, Regulatory Gu6 des are Issued to describe and make available to the pu bitc methods ec cept able to the N RC staff of 6m plemen ting specif 6C Parts of the Commiss6on's regulations, to defineate tech-The guides are issued in the following ten broad divisions:

'_N nt*ues used b / the staf f in evaluating specific problems or postu.

s t ted acc6 dents, or to provide guidance to appancants. Regulatory

1. Power Reactors

6. Products

} Cuides are not tut >stttutes for regulations. and compliance with

2. Research and Test Reactors

7. Transportation

/ thsm is not required. Methods and solutions dif ferent from thout set

3. Fuess and Mater 6als Facitelles

8. Occupat6onal Health s'

out in the guides will be acceptable if they provide a basis for the

4. Envaronmental and $ sting

9. Antitrust and F6nanclel Review finangs requisite to the issuance or continuance of a permit or

s. Mater 6als and Plant Protection IQ. General license by the Commission.

Copies of issued guides may be purchased at the current Government This gu6de was issued af ter consideration of comments received f rom Printing Of fice pr6ce. A suDscription serv 6ce for future qu6 des in spe-the pubeK. Comments and suecost6ons for emprovements in these c6f 6c divisions is available througn the Government Printing Of f 6ce.

gu6 des are encouraged at all t6mes, and guides will be revised, as informat6on on the subscriptlon serv 6ce and current GPO pelces may appropriate, to accommodate comments and to reflect new enforma-be obtained by wr6 ting the U.S. Nucsear Regulator Commission, 8808230055'830731 uon or e perience.

PDR REGGD

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a. The failure of the common sensingline would not of ISA S67.02 that sensing lines should be able to with-simultaneously (1) cause an action in a non-safety-stand.nd continue to perform their function.

related system that results in a plant condition requiring protective action and (2) also prevent

5. The special considerations in Section 5.2.2 of proper action of a protection system channel ISA S67.02 that should be addressed in the design and designed to protect against the condition. or installation of instrument sensing lines should be supple-mented with the following:

b. If the failure of the common sensing hne can cause an action in a non-safety-related system that

a. Instrument sensing lines that can be exposed to results in a plant condition requiring protective freeting temperatures and that contain or can be action and can also prevent proper action of a expected to contain a condensable mixture or protection system channel designed to protect fluid that can freeze should be provided an against the condition, the remaining redundant environmental control system (heating and venti-protection channels are capable of providing the lation or heat tracing) to protect the lines from protective action even when degraded by a second freezing during extremtly colu weather, random failure. The rupture of a scand instru-ment sensing line need not be considered as a

b. The environment associated with those instrument second random failure, sensing lines it. a that are safety related should be monitored and alarmed so that appropriate correc-Provisions should be included so that this requirement tive action can be tak:n to prevent loss of or can still be met if a channel is bypassed or removed from damage to the lines from freezing in the event of service for test or maintenance purposes. Acceptable loss of the environmental control system.

provisions include reducing the required coincidence, defeating the signals taken from the same sensing line in

c. The environmental control system recommended non-safety-related systems, or initiating a protective action in a., and for which b applies, should be electri-from the bypassed channel, cally independent of the monitoring and alarm system so that a sing'ca failure in either system,

2. The mechanical design requirements in Tables I and 2 including their power sources, does not affect the and Figures 1. 2, 3, 4, 7, and 8 of ISA-567.02 for instru-capability of the other system, ment sensing lines connected to AShlE Class 1 and 2 process piping and vessels should be supplemented with the

d. The environmental control and monitoring following:

systems of a. and b, should be designed to stan-dards commensurate with their importance to

a. Instrument sensing lines that are connected to safety and with administrative controls that are AShlE Class 1 or 2 process piping or vessels should implemented to address events or conditions that not be less than ash!E Class 2 Seismic Category I could render the systems inoperable, from their connections to the process piping or vessel to and including the accessible isolation

6. The Summer 1981 Addenda to Section ill of the valve.

AShlE Boiler and Pressure Vessel Code deleted Paragraphs NB 3676, NC-3676, and ND-3670 in their entirety. Refer-

b. Instrument sensing lines that are connected to ences to these paragraphs in Section 4.2.1, Section 6.2, AShlE Class I or 2 process piping or vessels and and Section 7 of ISA-S67.02 should be disregarded, that are used to actuate or monitor safety related systems should not be less than AShlE Cass 2 D. IMPLEMENTATION Seismic Category I from their connections to the process piping or vessel to the sensing instrumenta-The purpose of this section is to provide information to tion.

applicants and licensees regarding the NRC staff's plans for using this regulatory guide.

3. The mechanical design requirements in Tables 1 and 2

- and Figures 5, 6, and 9 of ISA 567.02 for instrument Except in those cases in which an applicant or licensee sensing lines connected to AShlE Class 3 process piping and proposes an acceptable alternative method for complying vessels should be supplemented with the following:

with specified portions of the Commission's regulations, the method described in this guide will be used by the NRC Instrument sensing lines that are connected to AShlE staff in its evaluation of the design and installation of dass 3 process piping and vessels and that are used to safety-related instrument sensing lines for all construction actuate or monitor safety-related systems should not permit applications issued after September 1,1983. Licensees be less than AShlE Gass 3 Seismic Category I from or other applicants may use this guide in discussions with their connection to the process piping or vessel to the the staff as it.stification for the adequacy of sensing line sensing instrumentation.

design and installation or for modifications to sensing line design and installation, flowever, the staff does not intend

4. Freezing temperatures should be added to the environ-to recommend the systematic application of every aspect of mental and installation conditions listed in Section 5.2.l(5) this guide to plants currently operating or under review.

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VALUE/ IMPACT STATEMENT

1. BACKGROUND the line meets provisions equivalent to the provisions of Sections 4.7.3 and 4.7.4 of IEEE Std 279 1971.

The licensee of a nuclear power plant is required by the Commission's regulations to provide principal design 2.2.1 Value criteria for those structures, systems, and components that provide reasonable assurance that the facility can be Any design in which a single failure could cause an event t

operated without undue risk to the health and safety of the and at the same time prevent mitigating action should be public. General guidance for the design and installation of avoided or additional redundancy should be provided.

Instrument sensing lines is given in Regulatory Guide 1.26, "Quality Group Classifications and Standards for Water,

2.2.2 Impact Steam, and Radioactive Waste-Containing Components of Nuclear Power Plants." The Instrument Society of America The avoidance of common-mode failures is a general (ISA) has developed more definitive guidance on instru.

design objective and consequently there should be no ment sensing lines in ISA S67.02, "Nuclear Safety Related impact.

Instrument Sensing Line Piping and Tubing Standards for Use in Nuclear Power Plants." The action endorses this additional guidance, with appropriate supplementary 2.3 Mechanical Design material,in a regulatory guide.

Regulatory Positions 2 and 3 were included to modify the guidance to make it consistent with the guidance of

2. VALUE/ IMPACT ASSESSMENT Regulatory Guide 1.26, 3.1 General 2.3.1 Value p

The guidance for design and installation of instrument The regulations require that components of the reactor sensing lines in ISA 567.02 is endorsed by this regulatory coolant pressure boundary be designed and erected in

guide, accordance with the requirements of ASME Class 1. After reviewing a number of applications for construction permits 2.1.1 Value and operating licenses and after discussions with repre-sentatives of professional societies and industry, the NRC The action should result in morv effective design and staff developed the classifications and guidance given in installation of instrument sensing lines, thus providing more Regulatory Guide 1.26, thus providing the assurance that assurance that the sensing lines will perform their safety structures, systems, and compments were designed and function undet all service conditions. It establishes the NRC erected (installed) to quality standards commensurate with position on a national consensus standard and therefore the importance of the safety functions to be performed.

reduces uncertainty as to what the staff considers accept-i able in the area of sensing line design and installation.

2.3.2 Impact Thers should be no impact since no new requirements 2.1.2 Impact are imposed.

Most of the impact on industry has already occurred during development, review, and epproval of the consensus 2.4 Environmental Conditions standard. Additional impact associated with the NRC i

endorsement of the standard should be minimal.

Regulatory Position 4 was included to add freezing temperatures to the list of environmental conditions to be r

l considered in the design of instrument sensing lines, i

2.2 Common 3ensing Lines v

Regulatory Position I was included to ensure that a 2.4.1 Palue single sensing line would not be used to perform a non-safety-related function and a safety-related function if the Instrument sensing lines should remain functionalunder failure of the sensing line could cause a transient and at the all emitonmental conditions. In the past, there have been same time prevent the mitigation of that transient unless many occurrences of froren instrument 'ines because P

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extremely cold temperature was not given adequate consid-2.5.1 Value cration in the design. Consequently, special attention must be given to prevent such occurrences.

The guidance provided is consistent with a technical position of the Instrumentation and Control Systems Branch (NRR) that was developed after it became evident 2.4.2 /r"rn t that froren instrument lines had become a problem. It ensures that the concerns of IE Bulletin 79 24, "Frozen There is no impact sinse this is not a new requirement.

Lines," were adequately addressed.

IE Bulletin 79 24,"Frozen Lines," was issued requesting all licensees and construction permit holders to ensure that 2.5.2 Impact freezing temperatures are taken into the design considera-tions for instrument sensing lines.

There should be no impact since no new requirements are imposed.

2.5 Environmental Control and Monitoring

3. CONCLUSION Regulatory Position 5 was included to provide guidance A regulatory guide endorsing 1,SA-S67.02 has been devel-in the design and installation of instrument sensing lines to oped to provide guidance for the design and installation of account for extremely cold weather conditions, instrument sensing lines.

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