Regulatory Guide 1.125

Rev 1,Physical Models for Design and Operation of Hydraulic Structures and Systems for Nuclear Power Plants

ML003739388
Person / Time
Issue date:	10/31/1978
From:	Office of Nuclear Regulatory Research
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RG-1.125, Rev 1
Download: ML003739388 (3)

U.S. NUCLEAR REGULATORY COMMISSION

Revision I

October 1978 REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.125 PHYSICAL MODELS FOR DESIGN AND OPERATION

OF HYDRAULIC STRUCTURES AND SYSTEMS FOR NUCLEAR

POWER PLANTS

A. INTRODUCTION

Paragraph (a) (3) (ii) of §50.34, "Contents of Applications; Technical Information," of 10 CFR

Part 50, "Domestic Licensing of Production and Utilization Facilities," requires that the Preliminary Safety Analysis Report (PSAR) include information on the design bases of the facility and the relation of the design bases to the principal design criteria.

Paragraph (a) (4) of §50.34 requires, in part, a preliminary analysis of the adequacy of structures, systems, and components provided for the prevention of accidents and the mitigation of the consequences of accidents.

This guide describes the desired coordination of an applicant with the NRC staff and the detail and documentation of data and studies that an applicant should include in the PSAR to support the use of physical hydraulic model testing for predicting per S

formance of safety-related hydraulic structures and systems for nuclear power plants. The regulatory position of this guide is applicable only to physical models used to predict the action or interaction of surface waters with features located outside of con tainment. The recommendations of this guide are not applicable to internal plant systems or structures.

The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position.

B. DISCUSSION

Physical hydraulic models are often used to predict prototype performance. They are particularly useful where hydraulic structures and systems are of unusual

• Lines indicate substantive changes from previous issue.

design or configuration and hydraulic parameters cannot be adequately evaluated by state-of-the-art analytical methods. Hydraulic models may also be used to establish conservative and reasonable design or operating bases for sites, structures, or systems involving thermal and erosional problems.

Examples of types of physical modeling studies include, but are not confined to, the following:

1. Intake structures.

2. Discharge structures.

3. Energy dissipation structures.

4. Spillway and tailwater ratings for dams (waterlevel discharge relations).

5. Release of water resulting from dam failures..

6. Wave runup, including tsunami effects.

7. Stability of structure when exposed to waves and protection therefrom.

8. Erosion and deposition in streams and other water bodies and protection therefrom.

9. Flow patterns and dispersion of heated or'

contaminated effluents in receiving water bodies.

10. Heat dissipation in receiving water bodies.

11. Response of moored floating bodies to incident wave systems.

12. Response of harbors to waves.

It has been the experience of the NRC staff that some applicants have not furnished sufficiently de tailed information on physical hydraulic model studies for.the staff to perform an adequate review. In some instances, staff involvement in the early plan ning of a model study would have resulted in savings.

of both NRC and applicant'funds and time in the review and acceptance of the results.

Accordingly, the regulatory position describes the USNRC REGULATORY GUIDES

Comments abould be sent to the Secreta*y of the Commison, U.S Nuc USNC

RGUATOY

GIDS

Rguatoy Cmrssan.Washington. D.C. 205 Attention: Dockein and Regulatory Guides are issued to describe and make available to -te public Servic Zranc

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methods acceptable to the NRC staff of implementing specific peats of the"

Commission's regulations, to delineate techniques usd by the staff in evalu- The guides are issued In the following ten broad divisions:

st specific Woblems oF postulated accidents, of to provide guidance to appelcantL Regulatmy Guides are not substitutes for regulations, and cor-

1. Power

. Products plieance with them Is not required. Methods arnd solutions differntfro ths

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atitn set out in the guides will be accepta"l if they provide a basis for the findinrs

3. Fuels and Materials Facilities

8 requisite to the issuance or cotnuance of a permit or licens by the

4. Environmental and Siting

9. Antitrust and Financial Review Commistion.

5.

& Materals Plant Protoctlot

10. Gnerwal Requests for single copie of Issued guides (which may be repoduced) or for Comments and suggestions for improvements in theae guides eae encouraged at placement on an automatic distribution list for single copias of future guides all times, and guides will be revised, as appropriate, to accommodate comrnents in specific divisions should be made in writing to the US. Nucla egulamry and to reflect new information or exaperience. This guide was revisd as a result Commission, Washington, D.C.

201.

Attention: Director, Division of of substantive comments received from the public and additional staff review.

Technical Information and Document Control.

I

documentation that should be furnished and the type of coordination bfveen the staff and the applicant that should minimize the time necessary for accept ance of the results of model studies.

The information described in the regulatory posi tion should be incorporated in the PSAR. However, the staff recognizes that it will not always be possible to incorporate such information in the initial applica tion for a construction permit since studies of this type may not be undertaken until after the PSAR is submitted. Such information may, therefore, be added to the PSAR by amendment, either by refer ence to separate reports or by insertion into the PSAR.

C. REGULATORY POSITION

Because not all hydraulic design problems can be resolved by the mechanics of similitude and because there are limitations to hydraulic modeling, the NRC

staff should be furnished. With certain documentation for any structural, thermal, erosional, or other physi cal hydraulic models used by the applicant to estab lish design or operating bases. The regulatory position contained in this guide *applies only to physical models used to predict the action or interaction of surface waters with safety-related features located outside of containment.

Generally, regulatory positions 1 and 3 describe information that should be furnished prior to actual model testing, and regulatory positions 4 through 6 describe information needed after testing' is com pleted. Additionally, partial test results should be provided for staff review and acceptance during the course of testing to ensure reconsideration of parameters whose importance emerges after partial data collection. After completing the entire study, all the information should be consolidated either (1) as a separate report with appropriate reference added in the PSAR or (2) for insertion into the PSAR.

1. Prior to construction of the model, the applicant should submit information outlining (a) the problem to be resolved, (b) reasons for selecting the hydraulic model chosen to resolve the problem, (c) expected results to be obtained, (d) a detailed description of the model,' including a description of materials, methods used to measure parameters, scale relations, and other physical characteristics of the model, (e)

methods that will be used to analyze the data obtained from the model studies, and (f) a schedule of expected tests, proposed completion dates, and estimated dates for submittal of information for NRC

staff review.

2. It is desirable that staff views and recommenda tions be solicited prior to model construction and following ot coincident with the submittal of the information listed in regulatory position 1 and that arrangements also be made for appropriate members of the staff to be present periodically during model operation to observe the actual performance of the model.

'3. Furnish documentation on how the various con ditions of geometric, kinematic, dynamic, and ther modynamic similitude that take into account the physical properties and flow state of the fluid (i.e.,

Froude, Reynolds, Euler, Cauchy, Weber, and other related numbers) have been considered. Because certain forces may act differently in a model than in a prototype, documentation should be provided to jus tify the neglect of any forces by showing that these forces (a) are of negligible magnitude, (b) compen sate for other neglected forces in such a manner that the effects of both are negligible, or (c) are such that their neglect leads to conservative model results and establishment of conservative design or operating bases.

Documentation should be furnished on the methods used to satisfy the equations of similitude in the model. Also document the effects of scale distortions on data obtained from the model studies. Where applicable, model adjustment and verification proce dures should be described, and information should be furnished on the validity of the model over a range of likely flow conditions, heat regimes, atmospheric conditions, and other physical parameters. Where applicable, demonstrate that the model will simulate known flow conditions, and provide this verification when historical data are available.

4. Where full-scale structures or systems having characteristics similar to those being modeled exist and information relative to the observed or measured performance of the existing structures or systems is available, the physical model results should be com pared with the available information generated by the existing structures. If testing is or has been per formed on existing full-scale structures or systems, such tests and their results should be described.

Document the applicability of such tests to the prob lem in question, and discuss any conclusions derived from the tests. If the results of other model tests are used by the applicant, justify the use of these results and verify the ability of these other models to reproduce or predict prototype performance.

Detailed documentation of data obtained from existing full-scale structures and systems should be provided, including (a) instrumentation used, (b)

description of the data collection network, (c) fre quency of collection, (d) methods of collection, and (e) physical parameters existing at the time of collection, such as heat regimes, flow conditions, and atmospheric conditions.

5. Any changes to the original design of the prototypes as a result of the model test should be discussed. Document the designs that were modeled and the basis for modifying the desig

n. Undesirable

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flow characteristics or failure modes for the design tested, as well as any other problems, should be discussed.

6. The report covering the completed model tests should include (a) instrumentation used, (b) descrip tion of the data collection network, (c) frequency of collection, and (d) method of collection. Figures, drawings, photographs, and text submitted as documentation for regulatory positions 3, 4, and 5 should be provided in sufficient detail to allow the staff to evaluate independently the applicability of the model to the design problem in question. (A typical model investigation reportI as published by the U.S.

Army Waterways Experiment Station has been found acceptable in the past.) Provide bases for the 'in terpretation of model results and for any conclusions

'Further information may be obtained by writing to the Com mander and Director, U.S. Army Engineer Waterways Experi ment Station, Corps of Engineers, P.O. Box 631, Vicksburg, Mississippi 39180.

reached. In many instances, it may be advisable to provide partial test results for review. The models should not be dismantled 2 until the staff has re viewed the submittals.

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 practice. There fore, except in those cases in which the, applicant proposes an acceptable alternative method for :com plying with specified portions of the Commission's regulations, the method described herein will be used in the evaluation of submittals for construction permit applications until this guide is revised as a result 9f suggestions from the public or additional staff review.

2 Preserving the model for a maximum of one year will be acceptable in most cases.

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