Regulatory Guide 3.11

Design Stability of Embankment Retention Systems for Uranium Mills

ML13350A256
Person / Time
Issue date:	06/30/1973
From:	US Atomic Energy Commission (AEC)
To:
References
RG-3.011
Download: ML13350A256 (2)

June 1973 U.S. ATOMIC ENERGY COMMISSION

REGULATORY

DIRECTORATE OF REGULATORY STANDARDS

GUIDE

REGULATORY GUIDE 3.11 DESIGN STABILITY OF EMBANKMENT RETENTION SYSTEMS FOR URANIUM MILLS

A. INTRODUCTION

Each licensee who piocesses or refines ore in a uranium mill is required to comply wiih the provisions of 10 CFR Part 20. "Standards for Protection Against Radiation."

Section

20.106.

"Concentrations in EIffluents to Unrestricted Areas." generally provides that licensees shall not possess. use.

or transfer licensed material s)

as to release to anl unrestricted area radioactive material in concentrations which exceed the limits. spccified in Appendix B. Tablc II of Part 20.

The milling ol' uranium ore results in the production of large volu nues of liquid and solid wastes. (tailings) both of which usually contain concentrations of radioactive material in excess of those specified in Table .11, Appendix B of Part 20. It is therefore necessary to confic such liquid and solid tailings and prevent their release to the environment. Conflnement is usually acconmplished by the construction of an embankment retention system.

This regulator),

guide specifies acceptable methods of analyzing the stability of embankments. minimum acceptable safety factors that are applicable during construction and use of embankment retention systems, and acceptable surveillance procedures.

B. DISCUSSION

'The design, construction. and size of embankment retention systems for uranium mill tailings will vary significantly from one milling location to another. The characteristics of these systems will depend on such diverse factors as the capacity of the mill. the type of ore processed.

the amount of waste produced. the amount of solution impounded, the type of milling process, the topography of the area in which thle mill is located, the amount of land thai is available for the retention systemn.

the perifeability of the soil on which tailings are deposited. and the materials with which the embanknments are constructed. It is imnportant that these embankment retention systems be designed and constructed in accordance with sound engineering principles to assure that they will maintain dtcir structural integrity.

Several analytical methods are available that may be used to determine the stability of emnbankments for various heights and slopes. seepage conditions, and soil strengtl" parameters. The results of such stability analyses should demonstrate an acceptable factor of safety against failure for all pertinent design conditions.

C. REGULATORY POSITION

I.

Basic Design Considerations Embankment retention systems for uranium mill tailings should be designed to assure structural integrity during the intended lifetime of the system. The stability of an embankment retention syslemn should be evaluated for construction and operating conditions utilizing the expected in situ engineering properties of the foundation and embankment materials and pertinent geologic information.

2.

Methods of Stability Analysis The acceptable methods of analyzing tihe stability of embanknients are the adaptations of lte circular arc method. Other proven methods of analyzing stability.

such as the sliding wedge method. may be used if they are more applicable to the particular situation being considered.

3.

Design Conditions for Analysis Stability analyses of embankments should be l.performed for the following design conditions:

a.

End of Construction (upstream and downstream slopes):

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ovaluating specific ptoblems or postulated accidents, or to provide guidance to Attention: ChlefPublic Proceedings Steff.

applicents. 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 itsued in the following ten broad divitions:

the guides will be acceptable If they provide a basis for the findings requitite to the issuance or continuance of a oermit or license by the Commistsion.

1. Power Reactors

8. Products permt by2.

Research and Trest Reactors

7. T'ransportation

3. Fuels and Matefiets Facilities

8. Occupational Health Published guides will be revised periodically. as appropriat

e. to accommodate

4. Environmental and Siting

9. Antitrust Review comments and to reflect new Information or eipetlence.

5. Materials and Plant Protection iO. General

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