Regulatory Guide 1.41

Preoperational Testing of Redundant on Site Electric Power Systems to Verify Proper Load Group Assignments

ML003740090
Person / Time
Issue date:	03/16/1973
From:	Office of Nuclear Regulatory Research
To:
References
RG-1.041
Download: ML003740090 (2)

,-"

U.S. ATOMIC ENERGY COMMISSION

REGULATORY

GUI

DIRECTORATE OF REGULATORY STANDARDS

REGULATORY GUIDE 1.41 PREOPERATIONAL TESTING OF REDUNDANT ON-SITE ELECTRIC POWER

SYSTEMS TO VERIFY PROPER LOAD GROUP ASSIGNMENTS

A. INTRODUCTION

General Design Criterion 1, "Quality Standards ai Records," of Appendix A to 10 CFR Part 50, "Genei Desigu' Criteria for Nuclear Power Plants," requires th structires, systems, and components important to safe be tested to quality standards commensurate with t]

importance of the safety functions to be performe Criterion Xl, "Test Control," of Appendix B to 10 CF

Part 50, "Quality Assurance Criteria for Nuclear Pow Plants and Fuel Reprocessing Plants," requires that a te program be established to assure that all testing requiri to demonstrate that structures, systems, aj components will perform satisfactorily in service identified and performed. For on-site emergency pow systems designed in accordance with Regulatory Guid

1.6 and

1.32 (Safety Guides 6 and 32) this gui4 describes an acceptable method of complying with tl Commission's regulations with respect to verifying tl proper assignments of redundant load groups to ti related on-site power sources. The Advisory Committ, on Reactor Safeguards has been consulted concernii this guide and has concurred in the Regulatory positio

B. DISCUSSION

An on-site electric power system designed accordance with Regulatory Guides 1.6 and 1.32 (Safei Guides 6 and 32) will consist of redundant pow sources and load groups that are independent of eac other. Such a design will conform to the provisions 4 Section 5.2.2(5) of IEEE Std 308-1971.'

Sectic

5.2.2(5) states: "Auxiliary devices that are required I

operate dependent equipment shall be supplied from related bus section to prevent the loss of electric powi I IEEE Std 308-1971, "Criteria for Class IE Electric Systei for Nuclear Power Generating Stations." Copies may be obtain from the Institute of Electrical and Electronics Enginee United Engineering Center, 345 East 47th Street, New Yoi N.Y. 10017.

in one load group from causing the loss of equipment in another load group."

The independence among Ad redundant on-site power sources and their load groups

.al should be such that the successful operation of any at power source and its load group is in no way affected by ty the partial or complete failure of any other power source he and its load group.

d.

'R

Since the reliability of an on-site power system of er the kind discussed in this guide is predicated on the

.st existence of this independence, a suitable preoperational

-d test to detect any lack of independence should be id performed. As a minimum, a suitable test should assure is that each redundant on-site power source and its load er group can function without any dependence upon any es other redundant load group or portion thereof.

de he lie

C. REGULATORY POSITION

he De As part of the initial preoperational testing program, nig and also after major modifications or repairs to a n.

facility, those on-site electric power systems designed in accordance with Regulatory Guides 1.6 and 1.32 (Safety Guides 6 and 32) should be tested as follows to verify the existence of independence among redundant on-site in power sources and their load groups.

ty

1. The plant electric power distribution system, er not necessarily including the switchyard and the startup

h and auxiliary transformers, should be isolated from the of off-site transmission network. Preferably, this isolation in should be effected by direct actuation of the

.0

undervoltage-sensing relays within the on-site system.

a

2.

Under the conditions of C.1. above, the on-site er electric power system should be functionally tested successively in the various possible combinations of ns power sources and load groups with all d-c and on-site ed a-c power sources for one load group at a time rs, completely disconnected.

Each test should include

• k, injection of simulated accident signals, startup of the USAEC REGULATORY GUIDES

Copies of published guides nmy be obtained by request indicating the divisions desired to the US. Atomic Energy Commission, Washington, D.C. 20645, Regulatory Guides ar issued to describe and make available to the public Attention: Director of Regulatory Stendards. Comments and sUggestions for methods amccptable to the AEC Regulatory staff of implementing specific parts of Improvements in thee guides "a encouraged end should be sent to the Secretary the Commission's regulations, to delineate techniques used by the staff in of the Commission. US. Atomic Energy Commission, Washington, D.C. 20645,

"evluating spedfic problems or postulated accidents, or to provide guidance to Attention: Chief, Public Proceedings Staff.

applicants. Regulatory Guides are not substitutes for regulations and compliance with them is not required. Methods and solutions different from those set out in The guides are issued in the following tan broad divisions:

the guides will be acceptable if they provide a basis for the findings requisite to the issuance or continuance of a permit or license by the Commission.

6. Products

2. Research and Test Reactors

7. Transportation

3. Fuels and Materials Facilities

8. Occupalional Health Pullo*ed guides will be revised periodically, as appropriate, to accommodate

4. Environmental and Siting

9. Antitrust Review coronst and to reflect new information or experience.

5. Materials and Plant Protection

1

0. General

3/16/73 DE

on-site power source(s) and load group(s) under test, sequencing of loads, and the functional performance of the loads. Each test should be of sufficient duration to achieve stable operating conditions and thus permit the onset and detection of adverse conditions which could result from improper assignment of loads, e.g., the lack of forced cooling of a vital device.

3.

During each test, the d-c and on-site a-c buses and related loads not under test should be monitored to verify absence of voltage at these buses and loads.

1.41-2