Regulatory Guide 1.35

Inservice Surveillance of Ungrouted Tendons in Prestressed Concrete Containment Structures.

ML12305A260
Person / Time
Issue date:	02/05/1973
From:	Office of Nuclear Regulatory Research
To:
References
RG-1.035
Download: ML12305A260 (3)

2/5/73 U.S. ATOMIC ENERGY COMMISSION

REGULATORY

DIRECTORATE OF REGULATORY

GI JIDE

STANDARDS

REGULATORY GUIDE 1.35 INSERVICE SURVEILLANCE OF UNGROUTED TENDONS

IN PRESTRESSED CONCRETE CONTAINMENT STRUCTURES

A. INTRODUCTION

preventing filler (grease). To the fullest extent practical, it should also cover the ducts that contain the tendons.

General Design Criterion 53, "Provisions for Such a surveillance program is necessary because Containment Testing and Inspection" of Appendix A generally there is no permanent instrumentation to 10 CFR Part 50, "General Design Criteria for installed in the containment that could continuously Nuclear Power Plants," requires, in part, that the monitor its structural behavior.

reactor containment be designed to permit (1) periodic inspection of all important areas and (2) 'an When developing a surveillance program, the total appropriate surveillance program. This guide describes containment tendon population should be divided into an acceptable basis for developing an appropriate homogeneous subgroups, i.e., tendons having surveillance program for ungrouted tendons in approximately the same probability of corrosion and a prestressed concrete containment structures of similar function in the overall structural capabilities and light-water-cooled reactors. The Advisory Committee properties of the structure. Thus, for each structure the on Reactor Safeguards has been consulted concerning surveillance program. should consider separately the this guide and has concurred in the regulatory position. groups of vertical, hoop, and dome tendons.

B. DISCUSSION

Consideration of homogeneous tendon subgroups (i.e., vertical, hoop, and dome) establishes a sampling This guide is applicable to "typical" prestressed base for determining loss of prestress, the main concrete containments with ungrouted tendons only, for characteristic checked by the surveillance program.

which the number of tendons does not exceed: 200 in the dome (either three families of tendons 600 apart or If some tendons are expected to be subject to two families of tendons 900 apart), 200 vertical (in greater prestress losses than the rest, this should be taken wall), and 500 complete hoops (in wall). into account in selecting samples..

For containments that differ from the "typical" The prestressing force in a tendon may :be 'checked containment described above, the model program by a liftoff or other equivalent test., One of the main presented in this guide should serve as the basis for objectives of the test is to discover any brittle, damaged, development of a comparable surveillance program. or broken wires. Any eventual decrease in the prestressing force is due to the simultaneous interaction Surveillance of ungrouted wire and strand tendons of several time-dependent factors such as:

of all sizes (up to an ultimate strength of approximately

1300 tons) and types should be considered (e.g., tendons a. Stress relaxation in the wire;

with parallel wires, with one or several strands, and with b. Temperature variation of the wire;

different systems of anchors). Materials for all c. Shrinkage, creep, and temperature stresses in components should satisfy the requirements of concrete;

applicable American Society for Testing and Materials d. Differential thermal expansion ' or contraction (ASTM) material standards. The surveillance program between the concrete and the tendon; and should cover the anchor hardware and the corrosion- e. -Eventual deterioration of the wires (corrosion).

USAEC REGULATORY GUIDES Copies of published guides may be obtained by request indicating the divisions desired to the US. Atomic Energy Commission, Washington, D.C. 20545, Regulatory Guides are issued to describe and make available to the public Attention: Director of Regulatory Standards. Comments and suggestions for methods acceptable to the AEC Regulatory staff of implementing specific parts of improvements in these guides are encouraged and should be sent to the Secretary the Commission's regulations, to delineate techniques used by the staff in of the Commission, U.S. Atomic Energy Commission, Washington, D.C. 20545, evaluating specific 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 ten 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. 1,. Power Reactors

6. Products

2. Research and Test Reactors

7. Transportation

3. Fuels and Materials Facilities 8. Occupational Health Published guides will be revised periodically, as apprupriate, to accommodate 4. Environmental and Siting 9. Antitrust Review comments and to reflect new information or experience. 5. Materials and Plant Protection 1

0. General

A liftoff test does not separate the effects of these accordance with this guide independently from factors, and corrosion, the factor of greatest concern, containments at any other site. Where identical cannot be isolated. Therefore, tolerance limits for the containment structures are located on one site, where no loss of prestressing force, including the effects of environmental or other differences are apparent, and possible corrosion, should be established, and the where they were constructed by the same contractor in surveillance procedure oriented toward verifying that the same manner at the same time (continuous these limits are not exceeded. However, it should be construction), then every second containment structure noted that only gross deterioration of the prestressing need only be visually inspected in accordance with C.7.

system can be detected.

3. Containments should be designed so that the Many hoop tendons are anchored on buttresses prestressing anchor hardware is accessible for periodic partially located inside the auxiliary building adjacent to inspection.

the containment. Since these anchors are not easily accessible, especially during operation of the facility, 4. The surveillance measures identified in C.5., C.6.

they present a special problem for liftoff tests. The and C.7. should be performed 1, 2, and 3 years after the original layout of tendons should address itself initial containment structural integrity test and every 5 specifically to this problem. Any anchor architectural years thereafter.

treatment or environmental protection should be removable without damage to the anchor. 5. Selected tendons should be periodically subjected to liftoff or other equivalent tests to monitor loss of Defects that an inspector might uncover during prestress. These tests should include the following:

visual inspection of the anchorage assembly should be a. Properly calibrated jacks and the simultaneous separated into three groups: measurement of elongation and jacking force. Allowable elongations and jacking loads, allowable tolerances, and a. Defects that can be found when the tendon is in its the effects of influences such as temperature should be normally stressed condition; established prior to the tests.

b. Defects that can be found only after the tendon is b. A maximum test liftoff force greater than the tensioned to a higher value than the existing prestressing maximum inservice prestressing force. The liftoff test force; and should include an unloading cycle going down to c. Defects that can be found only after the tendon is essentially complete detensioning of the tendon to detensioned. identify broken or damaged wires or strands.

c. Selected numbers and types of tendons If the limits provided in C.5. and C.6. are exceeded periodically tested for loss of prestress:

or if abnormal material behavior is detected pursuant to (1) Six dome tendons; two located in each 600

inspection in accordance with C.7., then abnormal group (i.e.., three families of tendons) and distributed to degradation of the containment structure, a boundary provide representative, sampling, or three located in each designed to contain radioactive materials, is indicated. In 900 group (i.e., two families of tendons), *

such cases, the reporting provisions of Safety Guide 16, (2) Five vertical tendons, randomly but

"Reporting of Operating Information," should apply. representatively distributed, Included in the report should be a description of the (3) Ten hoop tendons (where more than one condition of the concrete (especially at tendon tendon comprises the total hoop, one tendon may anchorages), the surveillance procedure, the tolerances represent the hoop), randomly but representatively on cracking, and the measures to be used when distributed.

tolerances are exceeded.

d. A measurement of the prestress force for each

C. REGULATORY POSITION

tendon tested in C.5.c., with acceptable limits being defined as not less than the predicted lower bound nor

1. This guide should be applied to "typical" greater than the predicted upper bound forces at the prestressed concrete containments having a time of the test.

shallow-domed roof on cyclindrical walls about 150 feet in diameter, an overall height of about 200 feet, and for e. An allowable limit of not more than one defective tendon out of the total sample population. If which the number of tendons does not exceed: 200 in the dome (either three families of tendons 600 apart or one sample tendon is defective, an adjacent tendon on each side of the defective tendon should also be two families of tendons 90' apart), 200 vertical (in checked. If both of these tendons are acceptable as wall), and 500 complete hoops (in wall). For defined in C.5.d., then the surveillance program should containments that differ from the "typical"

proceed considering the single deficiency as unique and containment described above, this guide should serve as acceptable. However, if either adjacent tendon is the basis for development of a comparable surveillance defective or if more than one tendon out of the original program, which will be evaluated on a case-by-case basis.

sample population is defective, abnormal degradation of the containment structure is indicated, and the

2. Each containment structure should be inspected in Commission should be notified in accordance with C.8.

1.35-2

6. The physical condition of the tendon material inspected to the extent practical without dismantling should be checked as noted below. load-bearing components of the anchorage. The surrounding concrete should also be checked visually for a. Previously stressed tendon wires or strands indications of abnormal material behavior. If the entire from one dome tendon and two wall tendons (one from containment is pressurized for leak testing purposes, the a vertical tendon and one from a hoop tendon) should visual inspection should be scheduled, if possible, to be removed for testing and examination over the entire coincide with the leak test.

length to determine if evidence of corrosion or other deleterious effects are present. At each successive The method used for checking the presence of inspection the samples should be selected from different sheathing filler grease should account for: (1) the tendons.

minimum grease coverage needed for different parts of the anchorage system including, for example, b. Tensile tests should be made on at least three buttonheads; (2) the influence of temperature variations, samples cut from each removed wire or strand (one at especially the lowest temperature likely to occur each end and one at mid-length; the samples being of a between two successive inspections; (3) the procedure maximum length practical for testing). If frequent stress used to uncover possible voids in grease in the trumpet;

cycling is suspected, tests simulating his condition and (4) requirements imposed by grease specifications, should be conducted. Similarly, where as a result of the qualification tests, and acceptability tolera'nces. The surveillance program a potentially corrosive atmosphere method used for removing grease in order to permit is suspected, accelerated corrosion tests should be made. visual inspection of the stressing washers, shims, wedges, and bearing plates should neither increase the effects of c. Failure below the guaranteed ultimate strength corrosion nor damage the steel (for instance, scratch it)

of any one of the three tendon material sample tests and should be usable even under unfavorable conditions should be considered an indication of abnormal so as not to conflict with operational requirements.

degradation of the containment structure, and the Commission should be notified in accordance with C.8.

8. Any significant or critical deterioration of the

7. Tendon anchorage assembly hardware (such as containment revealed by the inservice surveillance bearing plates, stressing washers, shims, wedges, and program should be reported to the Commission as an buttonheads) of all tendons inspected pursuant to C.5. abnormal occurrence in accordance with Safety Guide and C.6. should be visually inspected. For those 16, "Reporting of Operating Information," except that containments for which only visual inspections need be the initial report may be made within 10 days of the performed, as noted in C.2., the same numbers and types completion of the tests, and the detailed report may of tendons as noted in C.5.c. should be visually follow within 90 days of the completion of the tests.

1.35-3