Regulatory Guide 1.103

Post-Tensioned Prestressing Systems for Concrete Reactor Vessels and Containments.

ML13350A289
Person / Time
Issue date:	11/30/1975
From:	NRC/OSD
To:
References
RG-1.103
Download: ML13350A289 (4)

U.S. NUCLEAR REGULATO COMMISSION.

REGULkizORY

GUIDE OFFICE OF STANDARDS

DEVELOPMENT

REGULATORY

GUIDE 1.103 POST-TENSIONED

PRESTRESSING

SYSTEMS FOR CONCRETE REACTOR VESSELS AND CONTAINMENTS

November 1975

A. INTRODUCTION

(;General Design C(riteriun I. "Quality Standards and Records" of Appendix A. "'General Design Criteria for Nuclear I(oiver PlanIs." to 10 C(FR Part 50. *'Licensing if Prodlucion.

and Utilization Facilities.'- ,equires.

in part. that structures.

systems. and components im-lporlani to safety be designed.

fabricated, and erected to (tllality standards commensurate with the importance of Ihe saflcy luncliotins to be performed.

This guide identi-ties Ithe post-tensioned pcstressing systems Iltat hiave been reviewed and ai.rovcd by the NRC staff for use in concrete reactor vessels and containmnents and also describes qualifications acceptable to the NRC slafr for new post-tcnsioned prestressing systems.

B. DISCUSSION

A oims-tensioned prestressing system is composed ofa'prestressing tendon combined with a method of sira.sing and anchoring the tendon to thie hatrdened coz.crete.Th.e word "symeste is commonly associated ith the. dif-" fercn i proprietary post-tensioned prestrcssing.systenl oil Ihe market and is understood to include .the. type of tendon, anchorage device, and stressing equlipment associated with a given systemi.-.

It is not practical ito discussthe details or all of the many post-tensioned:.irestressilng sysiems available in the United States. Nlore)ver.'"inw pidit-tensioned prestressing systems are being: devclopod, and existing ones are being modified.

F-6r "te nsreas. the descriptions in this guide are to -systnis listed in Table A. all of which havbeel used or proposed for use.Some examples of use are presented in order to identify iiore specifically thie system being discussed and to provide a rel'erctice io some plants for %,'hich tile sysvetns in Table A have been proposed o, approved.

The ex:amples cited are not intended to *indicote any testriction or prel'evence in size of the tendot for a given system. Nor is this -uide intended 'to discourage the developmtent of refinements of curr.ent systems or the development of new prestressing systems or concep)ts."hte quatliflcat ions dhat a post-tensioied piestnessitig s'.stem should meet in order td ibe acceptable to tie NRC st-a Tare iden~ified in tlicaiegulatowv positioti.

Rock anchorage systems are..not covered by this guide.Types of Systems STlhie type tof tendon selected usually diclates the choice of stressing eqluipment and also affects the choice ,of end .atchorages.

Basically.

post-tensioued prestressing systenis can be separated into Ihree general categories by Ihe types oh terndon in use: wire, strand. and bar systems. lEtnd anchorages for these tendons are based ott either wedge or direct-bearing p.inciples:

sometimes a combination of ihe two is used. A description is presented below ot post-tensioned prestressing systems in ternis or types tit tendons and end anchorages.

Wire Systems. Wire systents employ a tumber ot parallel wires grouped to form a tetndon. Wires manufactured in the United States conforni to ASTMt Specification A-421. "Uncoated Stress.Relieved Wire for FPrestressed Concrete." This specification provides for wires of two types (BA or WA). depending on w\hetite tltey are to be used with buttons or wedge.type anchorages.

USNRC REGULATORY

GUIDES C,,,nierr-ns should be sent to the Secretarv of the U S Nuclear AreqUlallor Conui'I*,Ison.

Wasin~l~gtoni.

D C M56 Alttention Docketing ando Regulatory ire to and otike to Ihe Iyith. Seulit SeCtion .A methods acceptatle" o thtf NRC ftill tot rmpim enmrting specific par the rf Se Coninti.,5on I reguajutions.

10 delineatei techniques used by th" tiltl an ttvalu lb. qutirmtesate issued in Ihar following ton brand divisionh Chirq it spi'ct c rutalems, or vustl.fle~d .Atc~dnlel.

or to Iriovad. g lsani.n I,, itpli cants ARguldiriao Guidesi at.e not subslitults fot regulations.

and I Powser Reactors 6 Products with them inot retjtlleii Miridb dint SnIu Illto- fIoent front lhose set (,,ii itt 2 flese'rch and Yost Reacit% 7 Transtproation th: wit: he it th v'y provide a t ht,,% fit tie fandings requisite to 3

8a Occuptilonl Heoalth the islsum Illo itlt!tte .ii1 rt tir the ICunmnmisiOn

4 Ern-tioninientl and Siting 9 Antitrust Reirew C(rrrriietlsfl1 trait+ Stiajleslilis

1,14111 IiiLVitullill11t5 ii ttlhlse ajiantaits itlt. rielt l later

i. rts aild PIrItM

tO Genet a lt ii tt11 , .J q wil" it t1i. l ,l a iI t aIaiiiI .t-1lu ,ict..ill.....l..late

oin, MGMlls rid,1 tIa iiltte,'.t -ew it..I-li.iiiiiii t..(uial r --ý c ...l..irvit. .i1rntt...1it.

ian C(i:;aie of tulAtished guides rtady ble olbtainld lIv written request aidacating the INis iju li1.. ii tem .itm (l artaila ,it Iii t 1a 1111m1la .Ilrer its O , as, i i.'. .,il tie iPa divisions desired to the U tS Nucltear Regultatuor Commission.

W a~shtng lor .0 C tImulai ly usef ll iii t h li llil lii ' niri. .t l .t ..i ..i.. y IV .,..a....

IOt2 5, Allen tion D lte .lol. Office of ,Slandaidi Develtopm ent The BBRV system, developed in Switzerland by Birkenmaier.

Brandestini.

Ros. and Vogt. is a wire system used in both concrete reactor vessels and containments built in the United States. The main feature of this svstenz is the. use of cold.lormed buttonheads for direct bearing at each end of the wire.Tie prestressed concrete reactor vcssel (PCRV) of the Fort St. Vrain station in Colorado employs the B3BRV system with 169-wire tendons developing approximately

2000 kips capacity each. A number of 2-ontainnienls utilizing the BBRV system with 90, 163. 16). 170. and 186 wires per tendon have been built in the United Slates. The wire diameter is 1/4 inch (6.35 imm) in all cases except fur the 1 63-wire tendon, which uses 7-mm (0.28 inch) wire.Strand Systems. Strand systems employ a number of"'strainds" that are bundled into a tendon. A strand is made tip tof a number of factory-twisted wires.Stress-relieved strand is made in two forms. The first is the seven-wire strand. which conforms to ASTM Specification A-416. *'Uncoated Seven-Wire Stress.Relieved Strand for Prestressed Concrete.-

The second forni consists of larger strands Iltat are made of larger individu al wires anid may consist of more thian seven wkires per strand. vhe larger strands are not covered hy ASTM spicifications and have not been used for the construction of nuclear power plants in lhe United Slates.Strand systems have been introduced in the construc-tion of nuclear power plants by Strand-Wrap, N'SL.(Vorspann System Losinger).

Stressteel.

Freyssinet.

and SEEE (Societe d'Ettides et diEqtiipments d'Enterprises).

The last two systems were considered but have not yet been used in the United States in nuclear power plants.Both the Freyssinet and SEEE systems have been used in Europe on concrete reactor vessels.The Strand-Wrap system has been reviewed and approved only for applying hoop prestressing

1o soine PCRVs in the Ltnited States. The basic principles of applying ltoop prestressing to the PCRV by the Sirand-Wrap system are the same as those for conventional prestressed concrete tanks and circular liquid containers ithat have been built using wire-winding machines.

Steel-lined circumferential precast concrete channels are anchored to the outer cylindrical surface of the vessel by reinforcing bars extending radially inward from the precast channels.

The strand is anchored at one end by means of a tapered wedge grip in the rib between adjacent channels and then wound around the vessel at ihe design tension for a number of turns and anchored in the next adjacent rib. Each band of circumferential prestressing consists of multiple layers of strand wound onto these channels.

Each layer consists of one contittuottis length of strand. A maximum hoop prestressing force of about 6600 kips per linear foot of vessel height is being used in the design of the PCRV head region of the Dehmarva Summit Power Station.The VSL strand system was.developed in Switzerland.

This system employs a wedge anchorage for strands.Each strand is drawn through the openings of both the bearing plate and the anchor head and is held by a two-piece split cone wedged tightly against the inner surface of the anchor head. As an example. the conttainmnent of the Rancho Seco Nuclear Generating Station* in California employs the VSL system with tendons consisting of 55 strands. each tendon developing

2250 kips capacity.The Stressicel S/Il multistrand systemi was developed in the United States during 1967-1968 by Stressicel Corporationi in cooperation with llovwlett Machine Works. The system is characterized by a three-piece slotted wedge cone that grips three strands in its serrated teeth, with a number of wedges in a single anchor plate making up a ittllistrand lendon of the desired size.As at, example. the conlainment of the Three Mile Island Nuclear Station Unit No. 2 in Pennsylvania employs the St resstecl S/Il multistrand system coisisLing of tendons with 54 1/2-inch.

Grade 270K. 7-wire strands per tendon, each tendon developing

2230 kips capacity.The Freyssinet systemn was naimted after (ie French engineer Eugene Freyssinet.

who itivented the anchorage device in I939. The original anchorage device was for a wire system only, This is a comn monly used commercial system. The anchorage consists of a male conical plug and a female conical recess. The plug. with the wires spaced evenly around ils perimeter, anchors tile wire by wedge action.As a result of market requiremenmts and subsequent developments.

the Freyssinet system now also has available anchorages for strand tendons and other shapes of anchorage devices different fron the original one. The swame wedge principle for the tendon is retained, however. Concrete reactor vessels have becn built in Europe using the Freyssinet strand system with a maximum tendon capacity of abouw 2000 kips.The SlEHk system was developed in France by Societe d'Etudes Ce d'Equipnments d'Enterprises.

The system features threaded anchorage fittings extruded onto the ends of a group of strands. An anchoring nut is then threaded onto the anchorage fitting and turned tightly against (lte bearing plate. A tendon is composed of one or several such anchorage fittings on a common bearing plate.Bar Systems. Bat systems employ a number of high-tensile-strength steel bars that are bundled into a*The Irey-yinet.

SI-l-, and VSL systemsl were formally prt.m-niled is allternatives to Ile previomstiy approved IItIRV system. Thme V'SL syteim was chosen by Mhe applicant.

Consequently.

the Freyssinel and SIE systems were not rnvicwed by the NRC starf w ith regard to their acceptability for use in nutclear power plant Containments.

1.103-2 M tendon. "l Ie bars are mnade front an alloy steel conformiug to ASTM Specifications A-322 and A-29.A-322 is a general specificalion that covers only the chemical composition of many grade dcsignatioi., of alloy steel bars. and A-29 is a specification for generl requirements for hot-rolled and cold-finislted cat bun and alloy sled bars. No ASTM specinication covers the ininimuni mechanical and physical requtirementlls for the prestrcssing bars after processing.

as in the case (if' wires (A-42I ajnd strands (A-416) and it is for this reason that a speciticati )i* was written by tre Prestressed Concrete Institute.

Bars are cold-stretched and also stress-relieved by heat treatmenu Ito produce the prescribed mechanical properlies.

Bolih defornied bars and smooth bars with threaded ends are available.

hut only sinooth bars have been used for unclear plower plant conStructioll in tihe United Slates.The Stressicel Corporation in the United States employs a bar system. The bars are stressed by mneans of an hydraulic jack that consists of a coupler and pulling bar. The normal commercial tech tiique for anchoring uses anchor nuits. During stressing.

t[le anchor nuts are continuously screwed down on washers and bearing plates. and the prestressing force is then transferred to tile anchorage assembly by releasing the force in tihe jack. Wedge atn' grip-nut anchorages are also available to anchor the bar; they possess tile advantage of being able to grip the bar at any point along its length.The containment structure of H1.B. Robinson Unit No. 2 in ilartsville.

Soutlh Carolina.

employs lie Stresstecl bar system anchored with Howlett Grip Nuts.The tendon. comuposed of six I -3/8-inch-diatnuter Stressleel bars,. develops a cap',:ity of 1428 Kips.Grouted and Ungrouted Tendons All of the concrete reactor vessels and containments designed and built in tie United Slates use ungroited tendons except for H.B. Robinson Unit 2 (bar tendons), Three Mile Island Unit 2 (strand tendons), and Forked River (strand tendons), all of which were designed for grouted tendons. On none of these, however. has desigin credit been Oven for any bond of the grouted tendons.Whether grouted or ungrouted tendons are used, a means of determining ile functional capability oif [lie structure during its lifetime should be available.

This results in a need for reliable quality assurance procedures for t[le tendon installations and a need for a reliable structural inservice inspection program. To date, this has""(;uide Specification for Post-Tunsioning Materials," PCI Post-Tensioning Manual. Prestressed Concrete institute, 1972.been easier 1o acco inplish tltough lite use olftngrouted tendolns.C. REGULATORY

POSITION This regilatory

!!tuide the generic qualificatiors otf systenis lised in colnclete reactor vessels and conlainrlieits.

with Ilo) atlerlmi to extenid its scope to design aspecis. The accepiahility ol any posil-ellsiolled prestre.Nsirig syslelm ill conjunction with a specific structute design woitld lhave to bie evaluated on a case-by-case basis. Any proposed system submitted for NRC approval should consider tile following:

1. Post-tensiuned prestressitig systeirs that have beell approved in previous nuclear powcr plailt license applications are regarded as accepted systems. See Table A for idcntification.

When tie clain is nade by ail applicant that tile prestressing sysienr proposed is ail accepted systei., sufficient int' [rination shouttld be pro-vided with each iipplication to demonstrrtc that tile system proposed is the samne as tile that was approlJd iii !.ý'\vious muclear powel plant license ;ipplica iions. Pri:,-r approval of any system does Inol relieve tile applicanm of the responsibility for demonstrating that its svslenli leets all tle requirementIs of thle for Concrete Reactor Vessels and Containmenls.41

2. Changes in prestressiig element materials or in aichorage items of previously accepted systems that may require replieatig the., system peritrtnance tests are identified in Subsections

('11 and CC, Article 2406 of the Code for Concrete Reactor Vessels and Containmntetils.

3. Any new post-tensioned prestressing sysreiri should meet the requiremenls set fo7rth in tile Code to, Concrete Reactor Vessels and Containments.

4. The use of any prestressing system should permit the applicatio of ail iriservice inspection program that will verify the continued functional capability of tile structure.

Implemenlation of this program should not degrade the quality aid reliability of the post-tensiorled prestressing system.Regu.latory Guides 1.35. "'tisetvice Inspection ill UnIli.grouted Tendons iin Prestressed Concrete Containumen Strulctures.'

and I.90. "Inservice Inspection Pre-stressed Concrete Containnient Structures with (Grouted Tendons." should be consulted for recommiendations concerning the use of ungrouted and grouted concrete contlainrents, respectively."ASME Boiler and t'ressure Vessel ('ode. Section Itt. Division 2 (tile latest version, plus addenda, as endorsed by t(ie Nuclear Regutatory Commission).

This Code is currently under review f'or endorsement by the NRC staff.1.103-3 D. IMIVPLEMENTATION

porilons of't ile Ct ininlission'~s reglIluc ions. tile Ilethod dec~ribed hecrein %%ill be used inl tile evaluationt of suhbmittals for const ruction permit applicatiouns do cketed TheI. pur Ipos OfL 1 r iS isNC I io is ito provide ii tort u (on after J1 Liie 30, 1 976).(o alpp ic a mu s a utd li elscees regard in g tie staff's phlans for using~l this regullatory

-titl

e. I all applicant

%%ishles wo use this repuiit:Iory lideill.'hit lt lhoste cCases ill which theile aplicalt proposes aft;dernaltive metho)d fotr %%ith spec.ified developing submnittals tku applicat:ions docketed til or bel'ore JuIte 30. 1976. the pertinemn portlnuls oi tlie application

\Mi] lhe evailaied oin the basis ol" this puide.TABLE A STATUS OF SYSTEMS AS OF MAY 11975 1Por I. iccnlsh~ii Revi'it'.x IRr i e',s , i~ c iv i; iahl it A'RC staff use(/In US. A'tich'ar 1'oivvr I'lants 7',) Dim, 00, 1 w), 170.t,ý(. Wiles (1/4 ill. r0)163 W i 10s VS L.( 'sranlds)St re~sscel sti ra nuls)i st rall ()(5stratid)

strcssicel ( 6 1-.3X it.POW'R Strand.WVrap x x x N x x x x x x x x x I x X x x x x POSTAGE AND rccs PAID U.S. NUCLCEAR RCGULATORY

COMMISSION

UNITED STATES NUCLEAR REGULATORY

COMMISSION

WASHINGTON.

0. C. 20555 OFFICIAL BUSINESS PLNALTY FOR PRIVATE USE. S300 1.103-4