Regulatory Guide 1.141
| ML003740194 | |
| Person / Time | |
|---|---|
| Issue date: | 04/30/1978 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| References | |
| RG-1.141 | |
| Download: ML003740194 (2) | |
U.S. NUCLEAR REGULATORY COMMISSION
REGULATORY GUIDE
OFFICE OF STANDARDS DEVELOPMENT
REGULATORY GUIDE 1.141 CONTAINMENT ISOLATION PROVISIONS
FOR FLUID SYSTEMS
A. INTRODUCTION
General Design Criteria 54, 55, 56, and 57 of Ap pendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50, "Licensing of Production and Utilization Facilities," require that piping systems penetrating primary reactor contain ment be provided with isolation capabilities that re flect the importance to safety of isolating these piping systems. This guide describes a method acceptable to the NRC staff for complying with the Commission's requirements with respect to containment isolation of fluid systems.
B. DISCUSSION
Working Group ANS-56.2 of the American Nu clear Society Standards Committee ANS-50, Nuclear Power Plant Systems Engineering, has prepared a standard which specifies the minimum design re quirements for containment isolation of fluid systems that penetrate the primary containment boundary of light-water-cooled reactors. This standard was ap proved by the American National Standards Institute (ANSI) Committee N 18, Design Criteria for Nuclear Power Plants, and designated ANSI N271-1976,
"Containment Isolation Provisions for Fluid Systems. '*
The provisions of ANSI N271-1976 include minimum design, testing, and maintenance' require ments for the isolation of fluid systems that penetrate the primary containment of light-water-cooled reac tors. Requirements for the design and testing of power supplies, qualifying of Class IE equipment, and the design and testing of protection systems are outside the scope of this standard. These areas are not completely covered by the references given in ANSI
N271-1976.
Copies may be obtained from the American Nuclear Society,
555 North Kensington Avenue, La Grange Park, Illinois 60525.
This standard contains requirements indicated by the verb "shall"
and recommendations indicated by the verb "should." The recommendations as well as the requirements of the standard were evaluated with respect to importance to safety. All recommendations are considered to be of sufficient importance to safety to be endorsed along with the requirements given in the standard.
C. REGULATORY POSITION
The requirements and recommendations for con tainment isolation of fluid systems that penetrate the primary containment of light-water-cooled reactors as specified in ANSI N271-1976, "Containment Isola tion Provisions for Fluid Systems," are generally ac ceptable and provide an adequate basis for complying with the pertinent containment isolation requirements of Appendix A to 10 CFR Part 50, subject to the following:
1. Section 3.6.4 of ANSI N271-1976 states: "The closed system shall be leak tested in accordance with
5.3 of this standard unless it can be shown by inspec tion that system integrity is being maintained for those systems operating at a pressure equal to or above the containment design pressure." This excep tion to system leak testing is also applicable to closed systems inside the containment.
2. Section 4.2.3 of ANSI N271-1976 states:
"Sealed closed isolation valves are under administra tive controls and do not require position indication in the control room for valve status." Since the con tainment isolation valves are components of the con tainment isolation system, which is an engineered safety-feature system, all power-operated valves should have position indication in the control room.
USNRC REGULATORY GUIDES
Comments should be sent to the Secretary of the Commission. US Nuclear Regu Regulatory Guides are issued to describe and make aveilable to the public methods latory Commission, Washington, D.C.
20555, Attention Docketing and Service acceptable to the NRC staff of implementing specific parts of the Commission's Branch.
regulations, to delineate techniques used by the staff in evaluating specific problems or postulated accidents, or to Provide guidance to applicants. Regulatory Guides The guides ae issued i the following ten broad divisions are not substitutes for regulations, and compliance with them is not required.
1. Power Reactors
6 Products Methods and solutions different from those set out in the guides will be accept-
2. Research arid Test Reactors
7. Transportation able if they provide a basis for the findings requisite to the issuance or continuance
3. Fuels and Materials Facilities
8. Occupational Health of a permit or license by the Commission.
4. Environmental and Siting
9. Antitrust Review
5. Materialsand Plant Protection
10. General Comments and suggestions for improvements in these guides are encouraged at all times, and guides will be revised, as appropriate, to accommodate comments and Requests for single copies of issued guides lwhich may be reproduced) or for place to reflect new information or experience.
However, comments on thisguide,if ment on an automatic distribution list for single copies of future guides in specific received within about two months after its issuance. will be particularly useful in divisions should be made in writing to the US- Nuclear Regulatory Commission.
evaluating the need for an early revision.
Washington D.C
20555. Attention Director, Division of Document Control April 1978
3. Section 4.2.5 of ANSI N271-1976 states: "Di versity in means of actuation of automatic isolation valves in series should be considered to preclude common mode failure.
The NRC staff's position is that there should be diversity in the parameters sensed (i.e., types of isolation signals) for the initia tion of containment isolation.
4. Section 4.4.8 of ANSI N271-1976 gives general design requirements for closed systems. In addition, all branch lines and their isolation valves in closed systems both inside and outside the containment should meet the design criteria of Section 3.5 or Sec tion 3.6.7 if the branch lines constitute one of the containment isolation barriers.
5. In Section 4.6.3 of ANSI N271-1976, reference is made to Regulatory Guide 1.7, "Control of Com bustible Gas Concentrations in Containment Follow ing a Loss-of-Coolant Accident," for guidance in de termining radiation exposures for a loss-of-coolant accident. More appropriate guidance is given in Reg ulatory Guide 1.89, "Qualification of Class 1E
Equipment for Nuclear Power Plants."
6. Section 4.14 of ANSI N271-1976 states: "The piping between isolation barriers or piping which forms part of isolation barriers shall meet the re- quirements of 3.7 and applicable requirements for isolation barriers." Piping between isolation barriers should meet the applicable requirements of Section
3.5 or Section 3.7.
D. IMPLEMENTATION
The purpose of this section is to provide informa tion to applicants regarding the NRC staff's plans for using this regulatory guide.
This guide reflects current NRC staff practice.
Therefore, except in those cases in which the appli cant proposes an acceptable alternative method for complying with specified portions of the Commis sion's regulations, the method described herein is being and will continue to be used in the evaluation of submittals for construction permit applications until this guidance is revised as a result of sugges tions from the public or additional staff review.
For those plants for which the second round of questions (Q2) on the construction permit application has been received by the date of issuance of this guide, the recommendations of this guide will be considered by the staff on a case-by-case basis pur suant to §50.109 of 10 CFR Part 50.