Regulatory Guide 1.90

Inservice Inspection of Prestressed Concrete Containment Structures with Grouted Tendons

ML003740281
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Issue date:	08/31/1977
From:	Office of Nuclear Regulatory Research
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RG-1.90, Rev 1
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Revision i *

U.S. NUCLEAR REGULATORY COMMISSION August 1977 REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.90

INSERVICE INSPECTION OF PRESTRESSED CONCRETE

CONTAINMENT STRUCTURES WITH GROUTED TENDONSt

A. INTRODUCTION

deleterious environment, (3) the extent of temperature variations, and (4) the quality of the General Design Criterion 53, "Provisions for Con grout and its installation. Following the recommen tainment Testing and. Inspection," of Appendix A, dations of Regulatory Guide 1.107, "Qualifications

"General Design Criteria for Nuclear Power Plants," for Cement Grouting for Prestressing Tendons in to 10 CFR Part 50, "Licensing of Production and Containment Structures," could significantly reduce Utilization Facilities," requires, in part, that the con the danger of widespread corrosion. However, the tainment be designed to permit (1) appropriate mechanism of corrosion in all conditions and situa periodic inspection of all important areas and (2) an tions is not fully understood. Because many appropriate surveillance program. This guide parameters can influence the development of corro describes bases acceptable to the NRC staff for sion or stress corrosion, there is always an area of un developing an appropriate surveillance program for certainty with regard to the corrosion of tendon steel, prestressed concrete containment structures with and it is necessary to monitor the structure in a man grouted tendons. The Advisory Committee on Reac ner that would reveal the existence of widespread cor tor Safeguards has been consulted concerning this rosion.

guide and has concurred in the regulatory position This guide outlines the recommendations for inser

B. DISCUSSION

vice inspection of containments having grouted Inservice inspection of prestressed concrete con tendons of sizes up to an ultimate strength of approx tainment structures with grouted tendons is needed to imately 1300 tons (11,000 kN) and consisting either verify at specific intervals that the safety margins of parallel wires or of one or several strands. The provided in the design of containment structures have detailed recommendations of the guide are not direct not been reduced as a result of operating and en ly applicable to grouted tendon containments having vironmental conditions. Grouting of tendons to bar tendons. However, the inservice inspection protect them against corrosion is a proven program for grouted tendon containments with bar technology in other types of structures. However, tendons may be developed using the principles in this there is as yet no real experience to adequately define guide and will be reviewed by the NRC staff on a the long-term characteristics of containment struc case-by-case basis. This guide does not address the in tures with grouted tendons. The major concern in service inspection of prestressing foundation anchors.

containment structures with grouted tendons is the If they are used, the inservice inspection program will possibility that widespread corrosion of the. tendon be reviewed by the NRC staff on a case-by-case basis.

steel may occur and remain undetected. The major Inservice inspection of the containment liner and factors influencing the occurrence of corrosion are (1) penetrations is also not addressed in this guide.

the susceptibility of the tendon steel to corrosion, (2)

the degree of exposure of the tendon steel to a The simplest means of monitoring these prestres sed concrete structures would be to ascertain the

• The substantial number of changes in this revision has made it amount of prestress at certain strategically located impractical to indicate the changes with lines in the margin. sections in the structure. However, it is generally felt t For the purpose of this guide, a tendon is defined as a tensioned that available instrumentation for concrete, i.e.,

steel element consisting of wires, strands, or bars anchored at each strain gages, stress meters, and strain meters, is not end to an end anchorage assembly. reliable enough to provide such information. When USNRC REGULATORY GUIDES Comments should be sent to the Secretary of the Commission, US. Nuclear Regu Regulatory Guides are issued to describe and make available to the public methods latory Commission, Washington, D.C. 20555, Attention: Docketing and Service Branch.

acceptable to the NRC staff of implementing specific parts of the Commission's regulations, to delineate techniques used by the staff in evaluating specific problems The guides are issued in the following ten broad divisions:

or postulated accidents, or to provide guidance to applicants. Regulatory Guides are not substitutes for regulations, and compliance with them is not required.

t. Power Reactors 6. Products Methods and solutions different from those set out in the guides will be accept

2. Research and Test Reactors 7. Transportation able if they provide ovidens a ba basis for the fidings requisite to the issuance or continuance the findin. 3. Fuels and Materials Facilities

8. Occupational Health

4. Environmental and Siting

9. Antitrust Review

5. Materials and Plant Protection

10. General Comments and suggestions for improvements in these guides are encouraged at all Request for single copies of issued guides which may by reproduced; or for place times, and guides will be revised, as appropriate, to accommodate comments and mest onsan automatic distribution list for single copies of future guides iii specific to reflect new information or experience. This guide was revised as a result of divisions should be made in writing to the US. Nuclear Regulatory Commission, substantive comments received from the public and additional staff review.

Washington, D.C. 20555, Attention Director, Division of Document Control.

instrumentation that either can be recalibrated or concrete creep and shrinkage and relaxation of the replaced in case of a malfunction or is proven to be tendon steel.

sufficiently reliable is developed, monitoring the The measurement of forces in ungrouted test prestress level would be a desirable means of assess ing the continuing integrity of prestressed concrete tendons would provide a quantitative means of structures with grouted tendons. verifying the design assumptions regarding the volumetric changes in concrete and the relaxation of Another means of monitoring the functionality of prestressing steel. If some lift-off readings (or load the containment structure would be to subject it to a cell readings) indicate values lower than the expected pressure test and measure its behavior under pres low values, checks should be made to determine if sure. Industry comments indicate that an inservice in such values are due to corrosion of wires of un spection program based on the test of overall func grouted tendons or to underestimation of prestress tionality is preferable. ing losses. The plant need not be shut down or main tained in a shutdown condition during such an This regulatory guide provides two acceptable evaluation period. These tendons may also serve as alternative methods of inspecting containment struc an investigative tool for assessing the structural con tures with grouted tendons: (1) an inservice inspec dition after certain incidents that could affect the tion program based on monitoring the prestress level containment.

by means of instrumentation, and (2) an inservice in 2. MONITORING ALTERNATIVES FOR

spection program based on pressure-testing the con GROUTED TENDONS

tainment structure. a. Monitoring of Prestress Level (Alternative A)

The detailed inspection program outlined in this After the application of prestress, the prestressing guide is applicable to a sphere-torus dome contain force in a tendon decreases owing to the interaction ment having cylindrical walls about 130 feet (40 m) in of such factors as:

diameter and an overall height of about 200 feet (61 m) with three groups of tendons, i.e., hoop, vertical, (1) Stress relaxation of the prestressing steel;

and dome. For the purpose of this guide, such a con tainment is termed the "reference containment." The (2) Volumetric changes in concrete;

recommendations in the guide may be used for similar containments with cylindrical walls up to 140 (3) Differential thermal expansion or contraction feet (43 m) in diameter and an overall height up to between the tendon, grout, and concrete; and

210 feet (64 m).

(4) Possible reduction in cross section of the wires For containments that differ from the reference due to corrosion, including possible fracture of the containment or are under a controlled environment, wires.

the inservice inspection program may be developed using the concepts evolved in this guide and the In this alternative, the prestress level is monitored guidelines in Appendix A. at certain strategically located sections in the contain ment. Thus it is a sampling procedure in which degradation in the vicinity of the instrumented sec The inservice inspection program recommended in tion will be detected by evaluation of the instrumen this guide consists of: tation readings. However, if corrosion occurs at loca

1. Force monitoring of ungrouted test tendons; tions away from the instrumented sections, it would

2. Monitoring performance of grouted tendons by have to produce gross degradation before the in strumentation readings would be affected.

a. Monitoring of prestress level, or b. Monitoring of deformation under pressure; The prestressing force imparted to the structure by and a grouted tendon system could be monitored by an appropriate combination of the following methods:

3. Visual examination.

1. FORCE MONITORING OF UNGROUTED (1) Monitoring the tensile strains in the wires of a TEST TENDONS tendon;

Some tendons (otherwise identical) are left un (2) Evaluating the prestress level at a section in the grouted and are protected from corrosion with structure from readings of appropriately located grease. The changes observed in these tendons are not strain gages or strain or stress meters at the section intended to represent the changes due to environmen (see Refs. 1 through 7).

tal or physical effects (with respect to corrosion) in the grouted tendons. Instead, these test tendons will Method (1) above is useful for direct monitoring of be used as reference tendons to evaluate the extent of prestressing force in a tendon. However, the installa-

1.90-2

tion of the instrumentation required for this method anchorage takeup, and friction. The 8% bandwidth needs careful attention during installation and grouting of the tendons. Moreover, strain gages in would amount to between 40% and 70% of the total time-dependent losses.

%talledon the prestressing wires of a tendon will not detect the loss of force due to relaxation of prestress Alternative A is based on the use of instrumenta ing steel. Allowance for this can be based on relaxa tion. Many of these instruments have to be built into tion data for the prestressing steel used. the structure in such a manner that they can be neither replaced nor recalibrated. It is quite likely Evaluation of strain gage and stress meter readings requires a full understanding of what makes up the that such built-in instrumentation may not remain readings, e.g., elastic, creep, and thermal strain or reliably operable throughout the life of the structure.

stress components. Strain gage readings will consist Recognizing such a possibility, the guide provides for an alternative of pressure testing (Alternative B)

of elastic strains corresponding to the prestressing stress in concrete and strains due to creep and when the data obtained from instrumentation readings are found to be questionable.

shrinkage of concrete. Strains from creep and shrinkage of concrete can vary between 1.5 and 2.5 b. Monitoring of Deformation Under Pressure times the elastic strains in concrete. However, there (Alternative B)

are methods that can be used to isolate these effects.

Testing the containment under pressure and Three such methods are: evaluating its elastic response has been proposed as a

(1) Calculate average creep and shrinkage strains means of assessing the integrity of the containment.

The elastic response under pressure testing is primari from the time-dependent losses measured on the un ly a function of the stiffness of the structure. Any grouted tendons.

significant decrease in the stiffness of the structure

(2) Use stress meters at sections where strain gages due to loss of prestress would be the result of crack are used. ing of the structure. Because of the insensitive and in direct relationship between the prestressing force and

(3) Use special strain meters that respond only to the elastic response of the structure, such a method volumetric and temperature changes in concrete cannot be used to establish the existing prestress level (Ref. 7). at various sections. However, comparison of the con dition and deformation of the structure during the A sufficient number of temperature sensors instal ISI (Inservice Inspection) pressure testing with those led at the sections where instrumentation is located during the ISIT (Initial Structural Integrity Testing)

can be useful in isolating the thermal effects. It is pressure testing could provide a basis for evaluating recognized that the raw instrumentation readings can the functionality of the structure. This method has be deceptive, and adjustments may be necessary to been accepted* previously by the NRC staff on the account for the calibration constants and condition that the containment be designed conser temperature effects. The interpretation and evalua vatively so that there will be no cracking (or only tion of the results will be simplified if the instrumen slight cracking at the discontinuities) under the peak tation is provided at sections away from structural test pressure.Section III, Division 2, of the ASME

discontinuities. The applicant should provide suf Code (Ref. 8) allows a 33-1/3% increase in the al ficient redundancy in the instrumentation to permit lowable stress in tensile reinforcement under a test the evaluation of anomalous readings and the isola condition. The NRC staff has accepted this al tion of a malfunctioning gage. One such combination lowance on the assumption that it is only a one-time would be two strain gages and one stress meter at loading (i.e., during the ISIT). However, if such each face of a section. testing is to be performed a number of times during the life of the containment structure, it is prudent not After appropriate use has been made of the to use this allowance in order to avoid or minimize methods and instruments available, an average stress gradual propagation of cracking during subsequent and an average prestressing force at a section can be pressure tests.

evaluated. Even though the predicted prestressing force corresponding to a specific time may include The locations for measuring the deformations un adequate consideration for creep of concrete and der pressure should be based on the recommenda relaxation of prestressing steel, the chance that the tions of this guide. For a meaningful comparison of value based on measurements will compare well with the deformations, it is recommended that the loca the predicted value is small. Hence it is recommended tions where the deformations are to be recorded have that an applicant establish a band of acceptable deformations larger than 0.06 inch (1.5mm) under the prestress level similar to that illustrated in Figure 1. It calculated peak containment internal pressure as is also recommended that the bandwidth not exceed sociated with the design basis accident and that these

8% of the initial prestressing force at a section after considering the loss due to elastic shortening,

• Three Mile Island Nuclear Power Station Unit 2 and Forked River Nuclear Power Station.

1.90-3

Fi - Initial prestressing force at a section considering the losses due to elastic shortening, anchorage takeup, and friction.

PREDICTED PRESTRESS FORCE

(CONSIDERING HIGH TIME-DEPENDENT LOSSES)

4*

PREDICTED PRESTRESS FORCE

(CONSIDERING LOW TIME-DEPENDENT LOSSES)

w

0.9Fi

0

LIb a,M

I-

C,,J

U0

K O.8F1

0.7Fi

5 10 15 20 25 30 35 40

1 3 TIME IN YEARS

Figure 1. Typical Band of Acceptable Prestress Level

locations be approximately the same during the ISIT 3. The inservice inspection program should consist and the subsequent ISIs. This will require these loca of:

tions to be away from the areas of structural discon tinuities. Thus the number of locations for measure a. Force monitoring of ungrouted test tendons;

ment of deformations in typical cylinder and dome b. Periodic reading of instrumentation for deter areas wili be in excess of those recommended in mining prestress level (Alternative A) or deforma Regulatory Guide 1.18, "Structural Acceptance Test for Concrete Primary Reactor Containments." tions under pressure (Alternative B) at preestablished sections; and If an analysis of the effects of such parameters as normal losses in prestressing force, increase in c. Visual examination.

modulus of elasticity of concrete with age, and dif ferences in temperatures during various pressure tests 4. The inservice inspection should be performed at indicates that they could affect the deformations of approximately 1, 3, and 5 years after the initial struc the selected points, these parameters should be con tural integrity test and every 5 years thereafter.

sidered in comparing the deformations during However, when an applicant chooses pressure testing various pressure tests. (Alternative B) as a part of the inspection, the fre quency of inspections should be as indicated in

3. VISUAL EXAMINATION Figure 2.

Visual examination of structurally critical areas consisting of the areas of structural discontinuities 5. Alternative B may be substituted for Alternative and the areas of heavy stress concentration is recom A by the applicant if, at some time during the life of mended. Reference 9 provides excellent guidance for the structure, the inspection based on Alternative A

reporting the condition of concrete and should be does not provide satisfactory data. The details of used whenever applicable for reporting the condition such a substitution will be reviewed by the NRC staff of examined areas. on a case-by-case basis.

There are numerous examples of the use of pulse velocity technique to obtain information concerning 6. If the containment base mat is prestressed, its the general quality level of concrete. Based on ex proposed inspection program will be evaluated by the perience and experimental data (Refs. 10, 11, 12), a NRC staff on a case-by-case basis.

pulse velocity of 14,000 ft/sec (4300 m/sec) or higher indicates a good to excellent quality of concrete. For normal weight concrete, a pulse velocity of 11,000 2. UNGROUTED TEST TENDONS

ft/sec (3400 m/sec) or lower indicates concrete of questionable quality. Thus the technique can be used 1. The following ungrouted test tendons should be as part of the inspection of concrete containments installed in a representative manner:

when the visual examination reveals a high density of wide (>0.01 in. or 0.25 mm) cracks or otherwise a. Three vertical tendons, heavy degradation. The detailed procedure and b. Three hoop tendons, and limitations of the techniques are described in Reference 13. c. Three dome tendons for the design utilizing three 600 families of tendons.

C. REGULATORY POSITION

2. The ungrouted test tendons need not be in addi

1. GENERAL

tion to the design requirements.

1. All prestressed concrete containment structures with grouted tendons should be subjected to an inser 3. The ungrouted test tendons and their vice inspection (ISI) program. The specific guidelines anchorage hardware should be identical to the provided herein are for the reference containment grouted tendons and their hardware.

described in Section B.

4. The ungrouted test tendons should be subjected

2. For containments that differ from the reference to force measurement by lift-off testing or load cells containment, the program described herein should to assess the effects of concrete shrinkage and creep serve as the basis for developing a comparable inser and relaxation of the tendon steel. These data should vice inspection program. Guidelines for the develop be evaluated in conjunction with the overall struc ment of such a program are given in Appendix A to tural condition of the containment evident from the this guide. other examinations.

1.90-5

I LRT

SCHEDULE -A - - a -1

(10 CFR Part 50,

APP. J)

ISI SCH. - = --

1 5 D

PRESSURE PA PA

1 15 PA PA

LEVELS pN " PPD

30 35

20 25

10 15

0 1 5

• P -TIME AFTER ISIT - YEARS

KEY

PN - Normal Operating Pressure or Zero PD) - Containment Design Pressure PA - Calculated Peak Internal Pressure Associated with the Design Basis Accident ILRT - Integrated Leak Rate Testing ISIT - Initial Structural Integrity Testing ISI - Inservice Inspection Figure 2. Schedule for Inservice Inspections (Alternative B)

3. MONITORING ALTERNATIVES FOR c. Cyclic loading: 500 cycles of 600 psi (4.2 GROUTED TENDONS MPa) stress variation in compression.

3.1 Instrumentation for Monitoring the Prestress 2. The instruments should be protected against adverse effects of the expected environment in which Level (Alternative A) they will be located, e.g., electrolytic attack, including the effects of stray electric currents of a magnitude

3.1.1 Installation that may be encountered at the particular site and I. The prestressed cylindrical wall and dome structure. They should be protected against should be instrumented. This instrumentation may be temperature extremes to which they may be exposed either embedded in the concrete or inserted into the while the containment is under construction.

structure so that it can be maintained or replaced. 3. The sensitivity of strain gages should be Instrument types, locations, and quantities should be specified; the drift or stability under the conditions in selected to provide the best representation of I and 2 above should be accounted for in the prestress level in the structure. A sufficient number of specified limits, or the gages should be subject to temperature sensors should be installed to isolate and rec:libration in service.

evaluate the effects of variations in temperature gradients on the instrument readings and observa 4. The stress meters should be able to measure tions. Redundancy of the embedded instrumentation compressive stresses up to 2500 psi (17.2 MPa).

should be based on a conservative estimate of the 3.1.3 Monitoring Instrumentation Operability probability of malfunction of the instrumentation to be installed. After the installation of the instrumentation, all embedded strain gages and stress meters should be

2. The instrumentation in the concrete should be read every two months until the initial structural in arranged and distributed in such a manner as to per tegrity test (ISIT) is performed. The response of the mit evaluation of the prestressing levels and should instrumentation during prestressing and pressure be located: testing (ISIT) should be used to confirm their operability. After the ISIT, the monitoring of the in a. At six horizontal planes to measure the hoop strumentation should be continued every two months prestressing levels; to confirm operability of the instrumentation until the first inservice inspection. The monitoring fre b. Along three vertical tendons to measure ver quency may be reduced to once every six months tical prestress levels; thereafter unless local conditions or special circum stances dictate more frequent readouts. The c. Along three dome tendons for the design us operability of the instrumentation should also be ing three families of 600 tendons. confirmed during subsequent pressure tests. If anomalous readings are obtained, the reason for such

3. Sections through the structure should be readings should be determined. If it is determined selected- at a minimum of four locations in each that they result from defective gages, the basis for horizontal plane, three locations along each vertical such a determination should be justified.

tendon, and two locations along each dome tendon (see Figure 3). At these sections, the prestress level 3.2 Monitoring Deformation Under Pressure (Alter should be monitored by (a) a combination of stress native B)

meters or strain gages in concrete or on rebar at a minimum of two points through the section or (b) When it is planned to use this alternative as a part strain gages directly on tendon wires with a minimum of the total inservice inspection program, it is recom of 3% of the tendon wires instrumented. mended that the design of the containment structure include the following considerations:

3.1.2 Characteristics

1. Membrane compression should be maintained

1. Instrumentation provided for the determination under the peak pressure expected during the ISI tests.

of concrete prestress level should be capable of effec tive use over the life span of the containment struc 2. The maximum stress in the tensile reinforcing ture within specified operational limits under the fol under the peak pressure expected during the ISI test lowing conditions, unless otherwise defined by the should not exceed one-half the yield strength of the designer and approved by the NRC staff: reinforcing steel (0.5fy).

a. Humidity: 0% to 100%; 3.2.1 Pressurization b. Temperature: 0°F (-18°C) to 200 0 F (93 0 C); 1. During the first inspecticn, the containment and structure need not be pressurized.

1.90-7

DT-1 DT-2 DI-2 L T-3 DOME TENDONS AT 600

00 VI-i VT-1 VI-2 VT-2 VI-3 VT-3KEY

HI-1i HT, VT, DT - HOOP, Vertical, Dome

_T-i Ungrouted Test Tendons.

J HI-2 ' _ HI - Horizontal Planes to be Selected

1- HI- I -I for Instrumentation.

T _I H__ VI & DI - Vertical & Dome Tendons

, I -1- HT-2 to be Identified for Instrumentation.

HI-4 IFour Sections Along HI Planes, Three

'I _11 Sections Along VI Tendons, Two Sections Along Dl Tendons to be Selected for HI-5 - -Monitoring Prestress Level.

- -I

-I HT-3 0- Shows Selection of Sections Along HI-6 One Horizontal Plane, One Vertical Tendon,

_- - and One Dome Tendon.

I

I I

I I

300 1500 2700

CONTAINMENT CYLINDER - DEVELOPED

Figure 3. Containment Diagram Showing Typical Locations of Test Tendonrr Instrumentation

2. During the second and third inspections, the 3. Local areas around penetrations that transfer containment structure should be subjected to a max high loads to the containment structure (e.g., around imum internal pressure of 1.15 times the containment high-energy fluid system lines).

design pressure.

4. Other areas where heavy loads are transferred

3. During the fourth and subsequent inspections, to the containment structure (crane supports, etc.).

the containment structure should be subjected to a maximum internal pressure equal to the calculated A visual examination of structurally critical areas peak internal pressure associated with the postulated should be scheduled during all pressure tests while design basis accident. the containment is at its maximum test pressure, even if visual examinations of these areas have been con ducted at other times.

3.2.2 Instrumentation and Deformations

4.2 Anchorage Assemblies

1. Instrumentation similar to that used during the ISIT should be installed prior to the pressure testing Exposed portions of the tendon anchorage as for measurement of overall deformations at the sembly hardware or the permanent protection selected points. thereon (whether it be concrete, grout, or steel cap)

should be visually examined by sampling in the fol

2. The limit of accuracy of readings of the instru lowing manner:

ments to be used should be specified by means of an error band so that a meaningful comparison of defor 1. A minimum of six dome tendons, two located in mations measured during the ISIT and ISI can be each 60* group (three families of tendons) and ran made. domly distributed to provide representative sampl ing,

3. The points to be instrumented for the measure ment of radial displacements should be determined in 2. A minimum of five vertical tendons, randomly six horizontal planes in the cylindrical portion of the but representatively distributed, shell, with a minimum of four points in each plane (see Figure 3). 3. A minimum of ten hoop tendons, randomly but representatively distributed.

4. The points to be instrumented for the measure ment of vertical (or radial) displacements should be For each succeeding examination, the tendon determined as follows: anchorage areas to be examined should be selected on a random but representative basis so that the sample a. At the top of the cylinder relative to the base, group will change each time.

at a minimum of four approximately equally spaced azimuths. The inservice inspection program should define the defects the inspector should look for during visual ex b. At the apex of the dome and one intermediate amination of the exposed anchor hardware and point between the apex and the springline, on at least protection medium and should establish the cor three equally spaced azimuths. responding limits and tolerances. Special attention should be given to the concrete supporting the anchor

5. The intermediate pressure levels at which the assemblies, and any crack patterns at these points deformations at the selected points are to be should be observed and analyzed.

measured should correspond to those for the ISIT.

5. REPORTABLE CONDITIONS

5.1 Inspection Using Alternative A

4. VISUAL EXAMINATION

If the average prestress force along any tendon falls

4.1 Structurally Critical Areas below the acceptable band (see Figure 1), the condi tion should be considered as reportable.

A visual examination should be performed on the following exposed structurally critical areas: If the prestress force determined at any section falls below the design prestress force, the condition should

1. Areas at structural discontinuities (e.g., junction be considered as reportable.

of dome and, cylindrical wall or wall and base mat).

5.2 Inspection Using Alternative B

2. Areas around large penetrations (e.g., equip ment hatch and air locks) or a cluster of small If the deformation measured under the maximum penetrations. test pressure at any location is found to have in-

1.90-9

creased by more than 5% of that measured during the 6. REPORTING TO THE COMMISSION

ISIT under the same pressure, the condition should be considered as reportable. The reportable conditions of Regulatory Position C.5 could be indicative of a possible abnormal de

5.3 Reportable Conditions for Visual Examinations gradation of the containment structure (a boundary designed to contain radioactive materials). Any such If the crack patterns observed at the structurally condition should be reported to the Commission.*

critical areas indicate a significant decrease in the spacing or an increase in the widths of cracks com

D. IMPLEMENTATION

pared to those observed during the ISIT at zero pres sure after depressurization, the condition should be The purpose of this section is to provide informa considered as reportable. tion to applicants and licensees regarding the NRC

staff's plans for using this regulatory guide.

If the visual examination of the anchor hardware indicates obvious movements or degradation of the Except in those cases in which the applicant anchor hardware, the condition should be considered proposes an acceptable alternative method for com as reportable. plying with specified portions of the Commission's regulations, the method described herein will be used If the anchor hardware is covered by permanent in the evaluation of submittals in connection with protection and the visual examination reveals a construction permit applications docketed after degradation (e.g., extensive cracks or corrosion October 1, 1977.

stains) that could bring into question the integrity and effectiveness of the protection medium, the con If an applicant wishes to use this regulatory guide dition should be considered-as reportable. in developing submittals for applications docketed on or before October 1, 1977, the pertinent portions of

5.4 Reportable Conditions for Ungrouted Test the application will be evaluated on the basis of this Tendons guide.

When the force monitoring (by liftoff or load cell)

• The report to the Commission should be made in accordance of ungrouted test tendons indicates a prestress force with the recommended reporting program of Regulatory Guide below the acceptable band (see Figure 1), the condi 1.16, "Reporting of Operating Information-Appendix A

tion should be considered as reportable. Technical Specifications."

1.90-10

APPENDIX A

GUIDELINES FOR DEVELOPING THE INSERVICE INSPECTION

CONTAINMENTS (OTHER THAN REFERENCE CONTAINMENT PROGRAM FOR

DISCUSSED IN

THE GUIDE) WITH GROUTED TENDONS

Ungrouted Tendons Monitoring Deformations Under Pressure (Alternative B)

Three ungrouted tendons should be provided in each group of tendons (e.g.,vertical, hoop, dome, in The number of locations (N) to be selected for verted U). measuring the deformations under pressure should be determined as follows:

Instrumentation (Alternative A)

For radial deformations of cylinder, The following criteria should be used to determine the number of sections (N) to be monitored for each Surface Area of Cylinder infsquare feet group of tendons: (square meters)I

N =

2700 (250)

N = Actual Area Prestressed by a Group of Tendons K x Area Monitored by a Set of Instruments but not less than 12.

at a Section (determined as SxL)

where For vertical deformations. of cylinder, S = spacing of tendons in feet (meters) N=4 L = length of a tendon monitored by a set of instruments- may be considered as 12 ft (3.66m) For radial or vertical deformations of dome, and K is determined as follows:

For containments under uncontrolled environment Surface Area of Dome in square feet and having continuous tendon curvature, N = (square meters)

2700 (250)

K !SlO0

but not less than 4 For containments under uncontrolled environment and having essentially straight tendons, K: 160

For containments under controlled environment and having either straight or curved tendons.

K.200

1.90-11

APPENDIX B

REFERENCES

1. Jones, K., "Calculation of Stress from Strain in 6. Carlson, R. W., "Manual for the Use of Stress Concrete," U.S. Department of Interior, Bureau of Meters, Strain Meters, and Joint Meters in Mass Reclamation, Oct. 1961. Copies may be obtained Concrete." Copies may be obtained from Ter from the Bureau of Reclamation, Denver Federal rametrics, A Teledyne Company, 16027 West 5th Center, Denver, Colorado. Avenue, Golden, Colorado 80401.

2. Irving, J., "Experience of In-service Surveillance 7. Raphael, J. M., Carlson, R. W., "Measurement and Monitoring of Prestressed Concrete Pressure of Structural Action in Dams," 1965. Copies may be Vessels for Nuclear Reactors," a paper presented at obtained from Terrametrics, A Teledyne Company, International Conference on Experience in the 16027 West 5th Avenue, Golden, Colorado 80401.

Design, Construction and Operation of Prestressed Concrete Pressure Vessels and Containments for 8. "Code for Concrete Reactor Vessels and Con Nuclear Reactors, University of York, England, tainments," American Concrete Institute Committee Sept. 1975. Copies may be obtained from J. C. 359 and American Society of Mechanical Engineers Mundy, Publication Liaison Officer, Mechanical Subcommittee on Nuclear Power, 1975. Copies may Engineering Publications Limited, P.O. Box 24, be obtained from the American Society of Northgate Avenue, Bury St. Edmunds, Suffolk, Mechanical Engineers, 345 E. 47th St., New York, IP326BW. N.Y. 10017 or from the American Concrete Institute, P.O. Box 19150, Redford Station, Detroit, Michigan

3. Hill, H. T., Durchen, N. B., Brittle, W. F., 48219.

"Structural Integrity Test of Prestressed Concrete Containments," a paper presented at International 9. "Guide for Making a Condition Survey of Conference on Experience in the Design, Construc Concrete in Service," Reported by ACI Committee tion and Operation of Prestressed Concrete Pressure 201. Copies may be obtained from the American Vessels and Containments, University of York, Concrete Institute, P.O. Box 19150, Redford Station, England, Sept. 1975. Copies may be obtained from J. Detroit, Michigan 48219.

C. Mundy, Publication Liaison Officer, Mechanical Engineering Publications Limited, P.O. Box 24, 10. Whitehurst, E. A., "Evaluation of Concrete Northgate Avenue, Bury St. Edmunds, Suffolk, Properties from Sonic Tests," ACI Monograph No.

IP326BW. 2. Copies may be obtained from the American Concrete Institute, P.O. Box 19150, Redford Station,

4. Browne, R. D., Bainforth, P. B., Welch, A. K., Detroit, Michigan 48219.

"The Value of Instrumentation in the Assessment of Vessel Performance During Construction and Ser 11. Leslie, J. R., Cheesman, W. J., "An Ultrasonic vice," a paper presented at International Conference Method of Studying Deterioration and Cracking in on Experience in the Design, Construction and Concrete Structures," ACI Journal, Proceedings V.

Operation of Prestressed Concrete Pressure Vessels 46, No. 1, Sept. 1949. Copies may be obtained from and Containments for Nuclear Reactors, University the American Concrete Institute, P;O. Box 19150,

of York, England, September 1975. Copies may be Redford Station, Detroit, Michigan 48219.

obtained from J. C. Mundy, Publication Liaison Of ficer, Mechanical Engineering Publications Limited, 12. Van Zelst, T. W., "Concrete Quality Control P.O. Box 24, Northgate Avenue, Bury St. Edmunds, Instruments," ACI Journal, June 1975. Copies may Suffolk, IP326BW. be obtained from the American Concrete Institute, P.O. Box 19150, Redford Station, Detroit, Michigan

5. Arthauari, S., Yu, C. W., "An Analysis of the 48219.

Creep and Shrinkage Effects Upon Prestressed Concrete Members Under Temperature Gradient 13. "Standard Method of Test for Pulse Velocity and Its Application," Magazine of Concrete Through Concrete," ASTM Designation C597-71.

Research, Volume 19, Number 60, Sept. 1967. Copies Copies may be obtained from the American Society may be obtained from the Cement and Concrete As for Testing and Materials, 1916 Race Street, sociation, Wexham Springs, SLOUGH SL 3 6 PL. Philadelphia, Pennsylvania 19103.

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