ML18347A581
| ML18347A581 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 04/04/1975 |
| From: | Sewell R Consumers Power Co |
| To: | Purple R Office of Nuclear Reactor Regulation |
| References | |
| Download: ML18347A581 (20) | |
Text
/
Division of Reactor Licensing USNRC Att:
Mr. R. A. Purple Washington, DC 20555 Gentlemen:
Re:
consumers
- 1. Docket 50-255, License DPR-20 Palisades Plant
- 2. Letters to DRL From RBSewell Datedl2-29-74, 1-27-75 and 2-24-75 By letter dated November 26, 1974, the Atomic Energy Commission requested that Consumers Power Company review the Palisades Plant to de-termine whether the failure of any non-Category I (seismic) equipment, particularly in the circulating water system and fire protection system, could result in a condition, such as flooding or the release of chemicals, that might potentially adversely affect the performance of safety-related equipment required for safe shutdown of the facility or to limit the cop-sequences of an accident. It was noted that a previous review had been performed but in the intervening period the cooling towers had been com-pleted and a reanalysis should be conducted.
Consumers Power Company, in its letter of October 26, 1972, con-veyed its analysis and conclusion to AEC that a potential of flooding or chemical release, that would adversely affect safety-related equipment, does not exist at the Palisades Plant.
However, in light of the modifications to the circulation water system and the addition of cooling towers, an investigation of flood po-tential, that may have resulted from the modifications, was conducted.
1.0 DESCRIPTION
OF RELEVANT MODIFICATIONS Following is a brief description of the changes made in the circu-lating water system which have a bearing on the flooding potential:
- 1.
Removal of circulating water pumps from the intake structure.
- 2.
Addition of cooling towers.
- 3.
Layout of two 90" return pipes leading water from the cooling tower basins to the condenser:
This resulted in both the pipes travelling vertically downward through the intake structure.
,,I.)
i -.
Division of Reactor Licensing Att:
Mr. R. A. Purple 2
Docket 50-255, Letters to DRL April 4, 1975
- 4. Addition of two dilution pumps and associated piping in the intake structure.
- 5.
Addition of expansion joints and butterfly valves in the inlet piping to the condenser.
- 6.
Addition of expansion joints in the discharge piping from the condenser water boxes.
2.0 DESCRIPTION
OF ANALYSIS According to Attachment B of AEC - Branch Technical Position -
MEB #1, (Attachment 1), circulating water system is classified as a Moderate Energy Fluid System.
Paragraph C,Section II of AEC - Branch Technical Position -
MEB #1, implies that no break need be postulated.if the maximum stress in the nonnuclear pipi_ng is.less than 0.4 (1.25 Sh+ SA).
Stress analysis of the modified circulating water piping in the intake structure was carried out for various loads.
Maximum stress encoun-tered was found out to be much less than the permissible value re-ferred to above.
Therefore, no break in the circulating water system piping was postu-lated and no protective measures against flooding are required in the intake structure building (former screenhouse).
3.0
SUMMARY
4.o Circulating water system with its modifications falls under the cate-gory of Moderate Energy Fluid Systems {Attachment 1).
The actual stresses including seismic in the modified piping of the circulating water system in the intake structure building are much less than the allowable for a nonnuclear piping.
The stresses as calculated are l'.042 ksi as compared with an allowable value of 16.2 ksi.
Therefore, the postulation of any break in the circulating water piping in the intake structure building is not warranted and, as such, no protective measures are needed.
- . The addition of expansion joints and butterfly valves in the circu-lating water piping near the condenser has not altered the basis under which the previous analysis was made (10-26-72 letter to AEC).
CONCLUSIONS From the analysis above, it is concluded that modifications to the circulating water piping have not changed flooding potential in the intake structure (former screenhouse).
Therefore, no additional measures are required.
Note there is only about 22 feet of water static head (9.6 psi) in this part of the system.
Division of Reactor Licensing Att:
Mr. R. A. Purple Docket 50-255, Letters to DRL
. April 4, 1975 5.0 ADDITIONAL CONSIDERATION 3
In view of the Commission's concern regarding the expansion joints, an analysis was made assuming the rupture of only one expansion joint at a time, and limiting the size of rupture to half the cir-cumference of the expansion joint and a height *of four inches.
From this analysis, it was estimated that the minimum time taken by the*
leaking water to overflow onto the turbine building floor El 590'-0",
after filling the condensate.pump area El 571'-0" and condenser area El 580 1-0 11 is about 2-1/2 minutes.
To relieve this extremely unlikely discharge, we have decided to install two (2) level alarms in the condensate pump area (El 571'-0")
to detect rising water level.
These level sensors will provide sufficient warning to permit appropriate administrative action to be taken.
This action will include opening of the roll-up door at the turbine building floor area (El 590'-0") which by itself would limit the water buildup to a maximum of several inches (above the 590' floor).
This water level is considerably below the 593'-6" elevation which would result in flooding of the service water pump motor.
We expect to complete the installation of the level alarm by about October 1, 1975.
RBS/map CC:
JGKeppler, USNRC Yours very truly, Ralph B. Sewell Nuclear Licensing Administrator
From Draft 8 of Reg. Guide l.xx BRANCH TECHNICAL POSITION - MEB No. 1 POSTULATED BREAK AND LEAKAGE LOCATIONS IN FLUID SYSTEM PIPING.OUTSIDE.CONTAINMENT The following criteria are the review responsibility of the Mechanical En-gineering Branch with the exception of I.A. t II.A., and IJ.D. which are the responsibility of the Auxiliary Power and Conversion Systems Branch.
These items are included in this Branch Technical Position to provide clarity and continuity.
I.
High-Energy Fluid System Piping
-A.
B.
Fluid Systems Separated from Essential Systems and Components For the purpose of satisfying the separation. *provisions of plant arrangement as specified in C.1.a of the Regulatory Position,* a review of the piping layout and plant arrangement drawings should clearly show that the effects of postulated piping breaks at any location are isolated or physically remote from essential systems and components.
At the designer's option, break locations as determined from I.C and I.D of this Branch Technical Position may be assumed for this purpose.
Fluid System Piping Between Containment Isolation Valves.
Breaks need not be postulated in those portions of piping iden-tified in C.2.c. of the Regulatory Position* provided they meet the requirements of the *.ASME Code,Section III, Subarticle
- NE-1120 and the *following additional design requirements:
- 1.
The following design stress and fatigue limits should not be exceeded:
For ABME Code,Section III,.Class 1 Piping (a)
The maximum stress range should not exceed 2.4Sm (b)
The maximum stress range bet~een* any two load sets (including the zero load set) should be calculated by Eq. (10) in Paragraph NB-3653, ASME Code,Section III, for upset plant conditions and an operating basis earthquake (OBE) eve~t transient *
"\\
If the calcuL:itec! m:i:dmum stress range of Eq. (10)
-~ exceeds the li~it of I.B.l(:i) tut is hot greater than 3Sm' the limit o_f I.B.l(c) should.. be met.
If the calcul~{ted maximum stress range of Eq. (10) exceeds 3S_,_the stress ran~cs calculated bv both Eq. (12) a':la.Eq. (13) in Pa:-a6raph trE-J65J ~hould meet the limit of Lil.l(a) and the limit of I.B.l(c).
(c)
The cur::ulative usa;e factor should be less than 0.1 if consideration of fati~~e limits is required a.ccordin,; to I. I3.1 (b).
(d)
The oa:<inur:i stress, as calculated by Eq. (9) in.
Paragraph NB~3652 under the loadings resulting from a postul~ted piping failure beyond these portions of piping should not exceed 2.2~3.
m For-ASHE *code. Secticn III' "ClilSS 2 Pieing (a): The maximum stress ran~es as calculated by Eq. (9) and (10) in ~aragraph NC-3652~ AS~IB tode,Section III, considering upsat pZc:nt conditions. (i.e., sustair.ed loads, occasional loads, and thermal expansion) and an OBE event s_hould* not exceed 0.8(1.2Sh + SA)*
(b)
The maximum stress, as calculated by Eq. (9) in.
Paragraph NC-3652 under ~h~ loadinis resulting from a postulated piping failure of fluid system piping beyond these portions of piping should not exceed 1.BSh.
- 2.
Welded attachments, for pipe supports or other purposes, to *these portions of piping should be av0ided except where detail~d stress analyses, or tests, are performed
.to demonstrate compliance with the limits-of I.B.l.
- 3.. The nu6ber of ~ircumferential and longitudinal piping welds and branch connections should be minimized.* Where guard
. pipes are u~ed, the enc-lcsed. portion of fluid :;y:;te."':1 piping should be seamless construction unless specific access provisions are made to permit inservice volumetric examina-tion of the longitudinal ~elds.
- ... ~
- 4.
The le~~th of Ches~ portions of pipi~_*should ~ri reduced to the mlnimwn len&th practical.
- 5.
The design of pipe anchors or restraints (e.g., connections to containo:r.cnt pcnctr.1tions and pipe \\Vhip re:.traints) should not require weldiq;: directly to the outer surf.:ice of the piping (e.g., flucd integrally for~cd pipe fittings ~av be used) c:-ccept t.:hcre such -:.relcis -are loo* percent: voluonct:-ic<llly cxa~inablc in service and a detailed -stress analysis is pcrf orned to decons tr ate comp Hance with the limits of I. B.1.
- 6.
Guard* pipes provided for t~ose portions of piping ideQti:icd
- in C.2.c.(2)* of the Re?ulaiory Position* should be constructed in accordance with rules of Class NC, Subsection NE of the AS~IB Code,Section III, where the guard pipe is part of the*
containment boundary.
In addition, the entire guard pipe
- should be designed to meet t,he fo_llowing requirements and tests:
(a)
The design pressure anci temperature should not be less than the t:i.a:dmum operating pressure and ter.:iperature of.
the enclosed pipe under normal pla:nt*cor.ditions *
(b). 1'he design stress -limits of Paragraph NE-313l(c) should not be exceeded under the loading associated with design pressure and tet:lperature in coI!lbination with the safe shutdown earthquake.
(c)
Guard pipe assemblies should be subjected to a sin6le
.pressure test at a pressure* not in excess of design pressure.
C.
FZuid Systems Enclosed Within Prot:ective Structures i~
With the exception of "those portions of piping identified in I.B., breaks in Cl:J.ss 2 and 3 piping (ASHE Code,Section III) should be postulated.:it the following locations in chose
~ortions of each piping and branch run within a protective structure or co!i'lpartmcnt dc:signed. to s:J.tisfy the plant arrangement provisions of C.l.b. or C.l.c. of the Regula-tory Position:*
- See Attac~ent A
........ *~*................... ~-
- . *.. *.............,..._. ~~
Ll. At terminal. ewi:; of the run if located within the protective st~ucture.
bo At intermediate locations selected by_one of the following criteria:
(i)
(ii)
At each pipe *fitting. (e.g., elbo~, tee, cross, flancc, and non-standard fitting), ~elded attach-ment, and valve.
.i~*hcre the piping contains no fittings 7 welded attachLlc~ts~ or valves, at one location at each extreoe of the piping within the protective structure.
(A teIT.linal end, as determined by C. La, may be considered as one of these extremes.)
11*
At each location where the stresses-exceed 0.8(1.25iz + S 1) but at not less than two separated locations cho~en on the basis of highest stress."!:./
Where the pip~ng consists of a straight run without fit~ings, welded actachaen~, and valves, and all stresses are belov 0.8(1.25~ + SA), a QiniQum of.
one locat~on chosen on the basis of highest stress.
~reai:s in non-nuclear class piping should be postulated at the following locaticns in each piping or branch ru.*:
ao At temrina.Z ends of the run if located within the protective structure.
- b.
At each intermediate pipe fittingp welded a~tachment, and*valve.
l/ Stresses under r:orrr.c.l and l(OSet vlant condi-tion!J, and-an OBE event as calculated by Eq. (9) a.nd (10), Parag. ~C-3652 of the ASHE Code 1 Section III.
!/Select t"Wo locations with at.least 10% difference in st*ress,* or, if stresses di ff er by l~ss th.:m 10:~, two locations separated py a change of direction of the pipe run.
.*.*.~..........._ *.. *""'.**
4'***.*i.**........... -*****-*.... ?":i11-._....,,:. ** *,
s -
-~*
D.
Flu.id Sy:rt.tr.;:; !iot Enclpsed \\.lithin Protective Structures
- 1.
With the e::-:ceptions of those portions of pipinr, identified I
in I.B., breaks in Class 2.Jnd J pipin; (AS~IB Code,Section III) should be postul.Jtcd.Jt the f ollowinr, locations in those
- portions of each piping and br.:inch run rou.ted ouq;icJc of, but alon~sidc, above, ar bclo~. a protective struccur~ or comp.:irtncnt cont.::iinin; c~:::.::m;ial :;y:;t,.;;.::; *01d ccm;ior:cnts and designed to satisf~ the pl~nt arr~n~c~cnt provisions of C.l.b or C.l.c. of the Rcculacory-Position.*
Su~h _piping should b~ considered as loc~ted adjacent to a protective structure if the distance bet.,:ecn the piping and structure is ir.sufficient to. preclude iDpairr.:cnt of* the
_integrity of the structure fro::l the effects of a postulating pi~ing failure assuming th~ piping i~ unrestrained.
- a.
At terminal ends of the run if located adjacent to the.
protective structure.
- b.
At intermediate locations selected by one of the following criteria:
(i). At each pipe fitting (e.g., e1bo...,. tee,. cross,
- (ii)
- flange, and non-stC1I1dard fitting), welded Littac:i-ment, and v.Jlve.
\\~"here the piping COT1tains no fittings, welded attac~6e~ts, or valves, at one location at each extreme of the piping run adjacent to the protective structure.
1/.
At each location where the stresses-e:.;ceed 0.8(1.25h + S;,) but at not less than ti;,*o separL1tcd locations chosen on the basis of highest stress.~/
Where. the piping consists *of a straight run witryout fittings, weldad attach~ents, or valves, and all
- stresses are below O.S*(l.2Sh + SA)~ a minimum of one location_chos~n on.the basis of highest stress.
- 2.
Breaks in non-nuclear class pipim; should be pO"stul.1ted ac*
the*. fallowing locations in cpch piping or branch run:
- a.
At terminal ends of the run if-located adjacent to
. the protective structure.
b
- At each intermediate pipe fitting, ~elqed attachment,
. and valve.
- Sec Att~chmcnt A
- _,,;.\\.. -.
A
- Fluid Systc.-:-:s Separ.'.ltcd from E::;:;cntial Systc_r::s and Ccn;poncnts For the purpose of satizfying the separation provisions of plant arran~crnent as specified in C.l.a. of the Regulatory Position,* a review of the piping layout rind plant arrancc~ent drawinris*should clearly sho~ that the effects. of through-wall leakace cracks at any location are isolated or physically remote from e::;se;ztiaZ 3y:; t.;::.1:;. and componcnt3.
Bo Fluid S~stcm Piping Between Conta:!.nment Isolation Valves
- c.
D.
Leakacc cracks need not be postulated in th6se portions of piping idcritified in C.2.c. of the Regulatory ~osition* pro-vided thcv ~cet the rcouirc.:ilcnts of AS:-:::: Code,* Section III, Subarticlc ~E-1120, and arc dcsi~1ed such that the-~axirau~
stress range docs not exceed 0.4(1.25. +SA) *for ASZ*LE Code, Section III~ Class 2 piping.
n Fluid Syst(:;,;-.s Within>> or Outside and Adjacent to, P~otective Structure Through-wall leakage cracks should be pustulatcd in fluid syste~ piping located within, or outside and adjacent to, protective structures designed to satisfy the plant arrang~
ment provisions of C~l.h. o~ C.l.c of th~ Regulatory Position,*
' cxcepi (1) ~here exempted b~ II.B and II.D, ~r (2) where the maximum stress r~ngc in these portions of Class 2 or 3 pi~ing (ASNE Code,Section III), or non-nuclear piping is less than 0.4(l.2Sh + SA).
The cracks should be postulated to occur individually at locations that result in the Llaximum effects from fluid spraying and flooding, * *. :ith the consequent.hazards or environmental conditions developed.
Noderate-E-..iergy Flu.id Systems in Prcixir.ri ty to High-Energy FZ7:J-i~ Systems Cracks need not be.postulated in mcderatP--Cn(1I'~'J flz!id s1::*=tcm piping located in an area in which a break in fiqii-e~~rgy fZuid system pipinB is postula~ed, provided such cracks would not result in ::iore limiti_nc en**1ironi;.cntal con~itions th.Jn the hi:;h enercy piping brc.:Jk.
Where.a postulatec! leak.:i;;e crack in the moderate-energy fl~lid system piping results in more limiting Environmental conditiohs than the.break in proximale high-cnel'!J!F fluid c.y:;te_m pipings. the provisions of II. C should be applied.
- sec Attachment A
E.
i'Zi.dd Sys t-cm~ Qu:llHy~ng as High:-Enorgy or Moderate-Energy
§yste.-:-;:3 1h~~uch~~all leaka~e cr~~ks instead of breaks may be pcstula.tcd in ~he piping of tho.sc
- fZ:dd. syst~ms that qualify as izigh-~r.crgy fluid f"~:G :.;:-:':3 for only sher t opera ciona.l periods~./ buc qualify e!> m9detc:.te:::eni?rgy flu.id sys~ems ~or the major opera t~onal period.
~
?-!~* 'l"vn2 of BrC':1ks
~11d Lc;ik.:?r.c Cracks in FZ~d.d S11.~t-~m Pinin~
A.*
~~r~u;nfrrc*n t fol Pipe Er.e2ks
~*'1c follo*~*int: circu::1fcrcnti.:il breaks should be postulated in 1~~gh~enc!'G£i ffoid :;:1s~~m piping at the locations specified in Section I of this Branch Technical Position.
~~~cumfcrcntial breaks should be postulated iri fZuid_systam p~p~ng and branch runs exceeding a no~inal ~ipq size of l inch, except where the r.ta:dmum str~ss ranee.. !/ e:,ceecs the*
~!~J~s specified in* I. C. l. b*. (ii) and L D. l.b. (ii) ~~*:the*
f~F~u;f~rential stress range is ac lease 1~5 times the a~ial
!>~F~~s ~angc..
Ins~rurilcnc lines, one inch and less nominal p~pe 9r ~~b~ng size ~~9~~~ ~~~~ ~h~ p~9v~~~~ns of ~~g~~?~piy G~f8! J.* !J.
- Fhere b;.eak loc;itions at"c selected without the benc~it of
~~~~~s - ~~icul~ci~c~~, br~~ks * ~hould be pas tu la tcd a c each p!p~pg we~d jo~nt to fitting, valve. or we~ded attachmenc.
. AH~n:~~~vely, a single break location.ci*t the sect.ion of.
maximum stress range rnav be selected as dcter~incd by
- ~~~~~ied-~tress~a~~lyse~ ~e.g.~-finite ~~~~~nc ?n~~Y~~s)
~F ~g~~'.~n ? p~pe t~~~~ng.
~!~~~mfer~nt~al breaks should be assu~cd to result in pipe
!~Y~r?n~e and separation a~ount~ng to ~t.least a on~=dia~eter*
i!~~~~~ ~~~placemen~ of the ruptured pip~ng se~tio~s unle~s PhY~!~~!~Y ~imite~ by pip~ng res~rain~s, structural members, e~* p~p~ng stiffness as may be d~rr.onstrated by. inelastic
!!~~~ ?~a~ysis (e.g., a p~a~~~c h~nge ~n ~~~ p~p~ng ~s noc
~~Y~~9P~~ ~nd~r ~9~~~ng).
- ~-'.~~ ~P~ra~~onal period ~s cons;_dcred '"sho~t" +f th2 r!="action of time ~hat the system opcrat~s within ~l1e pressurc=t~moeraturc c6nditions specified.
~~~ ~j~~~energy fluid.systam3*~~ less than~ percent 6f the time that th~
~y~~g~ ppe~a~es as a ~oderate=ene1~y fluid system (e.~., systems such as t~~ ;-~~i;:~o~ decay h~at rer.:oval sys¢ems qua!~fy as.moaerate=-e11ergy fluid
~yptem~; ho~ever, syst~ms such ~s a~~i~~~~y feedw~ter systems operaced p'µ~~ng PWR rc.:ictor startup, ho~ standby, or shuc;do~*n qualify as high-:-
. ~n~r~µ f?uicj. ell~ tcm~)
r
~-** -* ---.... ':'..
~.
.e
<> 8 -
111e dy11.:?r.iic force C'f the jet disch.'.lrr.e at,ti1c break loc.:itioo should be b.:iscd on the effective cross-scction.:il flo~ are.:i of the pipe.:ind on n c.:ilc* *..:itcd fluid prcss1:re c'.lS mociificd by an an.:ilytic.:illy or c::-:pcr.ir.icn.t.:illy cictcrnincc..l thrust co-efficient.
Limited pipe displ.:iccment.:it the bre.:ik location, line restrictions, flow li~itcrs, positive pu~p-controlled floi..* 9 and the cibscncc of encrr,y reservoirs r.::;y be *t.:ikcn into account, as ap*?lic.:ible, in the reduction of jct ciischaq~c.
So Pipe whipping should be assu=cd to occur in the plnne defined by the pipin~ sec~ctry and confi~uration,.:ind to cause pipe movement in the direction of-~he jet reaction.
B.
Longitudin.:il Pipe Breaks The folloh*ing lont,itudin.:il breaks should be postulated in t!~*q;,_
enei*gy jluicl. s;,;s ':Cr.1 pi pin£ <it the locations of each circu:::if er-eotial break specified in III.A:
- 1.
Longitudinal l;>real:s in fluid system "piping and branch runs should be postulated in nominal pi~~ sizes 4-inch and larger, except ~*here the u:;:i:-:ir.ium stress ran£ cl:/ exce.cd~ the liT!li ts spcc;ified in LC.Lb. (ii) and I.D.l.b. (ii) h-l~-the a:*:ial stres::; range is at least LS times the c.ircur:iferential stress range
- Longitudinal breaks need not be postulated at:*
(a) terminal. ends provided the piping at the tc!'minal e.nds contains no longitudinal pipe '"~elds (if longitudinal welds are used, the requir~ments of IILB. l apply).
(b) at i~tcn:iediate locations ~here the criterion for a*minimum number of break locations niust be satisfied.
3.*
Longitudinal breaks should be assumed to result in an axial
~plit without pipe s~verance. Splits shbuld be oriented (but not concurr~ntly) at two di;:inctric~ily-opposed points on the pipin£ circu"mference such. that the jet re.i.cticn causes ciut~of-gl.::i.:i.e i.>.:nuing of the ?ipini; ccufigur.:itior:..
Alternatively, a sin~le split may'bc assuMed ac the $ectiun of highest tensile stress as det~rmined by dcta~lcd stress
.analysis (e.g., finite element analysis).
The dynamic force of the f 1-uid jet discharge should be based on a circul.:ir or cll;l.ptical (2D x 1/:20) break area eqtial to the effective cross-sectional flow area of the
- 5.
pipe at the brc.:i.k lrication and on a c.:ilcul.,tcd fluicl pressure moc.l if iccl I'.; ;in..:in.:i.lytically or c:-:pe rir.1cn tail:;
dctr,..rained thr.~st coefficient 01s determined for a ciri...J*rnfcrcntial break.:i.t the snmc location.
Linc restrictions, flow limiters, po~itivc pump-controlled flow, and the absence of cncr(!y reservoirs may be taken into <iccount>> as.Jpp1icablc, in the reduction of jet disch.'.lq;c.
Pipinr, r.mvcmcnt should be a.ssuned to occ11r in the direction of the jct re<1ctio;1 unless li:-Jitccl by suuctt:ral ticr::bcrs, pipinc res train ts, or p::..p1ng *s tJ.t rncss i!.S dcrwns tr.'.l t.cd by incla~tic limit analysis.
C~
Throur;h-t'.'.lll Lc.:!~age Cracks The f ollmdn;; throur,h-*,,*all leakage cracks should be postulated in mC1dcrate-c1:.z1*1;;:.1 fl.:.i.iC.
G~;:;t2r:i pipinr, at. the locations specified in Section II of this Branch Technical Position.
- 1.
Cracks should bi postulated in moderate~energy.fluid Gyst~m piping and branch runs exceedin~ a nominal pipe size of 2 *
- 3.
1 inch
- Fluid flow. from a crack should be based on a ci~cular opening of area equal to that of a rectangle one-half pipe-dir..meter in leugth.and one-half pipe wall thickness fn width.
The flow from the crack should be assu~ed to result in an environnent that ~.,;ets all unprotected cor.iponents wi :::hin the compartment, with cons~quent flooding in *che conµ2rtment and communicating compart!ilents.
flooding eff cc ts sho1Jld be determined on the b~sis of a conservatively esti~ated time period required to effect corrective actions *
- ATTACU:-:ErtT A Rcgulat0rv Position C.1..'.l Plant <lrrangc:::cnts should* sqi.'.lratc f"1:1id ayster.i piping fror.i ea:;cntic.l syst.7lS a>;ci cc:.;~-;cnc1:::::;.
Scpar.'.ltion should be achicvcci b:,* pl.'.lnt physic.'.ll layouts th.:>t pro*:icic suificicnt di~t:mccs bct*.. :ccn.;::;:;,-;r!~:.~~ s~1stc;-;;3 and ccr~;?or.c1::s ~nd fZ.1iiC.
- ~
- ::tcm p_ip:ing such th.'.lt the cffcct:-s of any post~~lat.::d pi?*~;:~; jc;ilii!.'t.: therein (i.e., pip~ \\o.'hjp, jet ir.rp:in~c:;.ent, and the. cnvironffiental *conditions resulting from tl1e escape of cdntaincd fluids as appropriate to ::igiz or r.:cC.er=:.:a-~ne?'(1:_,i flz1.id. s1_1st.:Jm piping) cannot i~?air the integrity or operability of esae1z~ial syst~ms and cQmponcm ts.
Re~ulatorv Po~ition C.l.b Fluid syst~m pipinc or portions thereof not satisfying the provisions of* C.l.a should be enclosed ~ichin structures or compartments dcs~gned to protect ne.J;:-by ess.::.r.tic.l S:,fstar.:s ar.d corr.ponen.ts.
AlterP-atively, essential S!IG't.;)r;;S LD!d COr.:DOl"!e1~tS may be enclosed within* structures or compartG1cnt~ designed. to ~*ithst.:md 'the effects of postulated piping failures in. nearby fluid. sys c;;;ms.
Rcgu:~torv Position C.l.c Plarit arrangem~nts or system.fcatur~s that do not *s3tisfy the provisions of either C.l.a or C.l.b. should be linitcd. to those for which th~ <ihcvc provisions.'.lre i~practical because of the stage of design or con£truction of the plant; bec~use the plant design is based upon that of an earlier plant accepted by the.staff ~s a base pl~nt undct' the Co;::;;iission 's st.1r:d-ardization and r~plication polic'; or for other subst3ntive reason~ such as particular cjcs ign features of the fl,;.1iC.. :J":J'S rer:::;.
Such ca~es may arise for exa:;iple, (1) at interco-::nections between flw:d systems and 2::;s~n.r;ial systems G:'.ld co.~onci~t::;, or (2) in 'fluid s'ys'f;ems having dual functions (i.e.,. required to operate c!uring 1~01*1~az olan.t cor:ditic!1.2-o.s well a::; to shut dm.. 'Tl the.reactor).
In these cases,. ~ccundan t desi~n f ~a tc-;:-es that are separated cir other'Wi~e protected frorr. pcstulat~d pipi>7?, fa1:lia*cs, or additional p*otcction, should be pro*1iJed, so thLl't the cf f,"?i:ts of postulctcd piti.1::1 _;-*c-=.Z.w*cs are sho1..-n *by the analyses and ;:uiclclfocs of
- C.3 to be acceptable.
Additional protection may be provided by rcstrLtints and bar_riers or* by designing or testing essential s~1ster;;s and component:;
to withstand the effects associated with postul.a.tcd piping failures
- 1\\-Z Rcculatotv ro~ition C.2.c FZ.u.id G!1::;t,-:m pipinr. bett.:ecn cont<linmcnt isolation valves should meet the follo~ing design provisions:
- 1.
Portions of ffo~d :;y:;tcm piping between isol:ltion v.:ilves of. siri.gle barrier co~t~i~~~nt structures (including any ri~id connection to 2 *
- 3.
- the cont:1in::-:cnt renctr.:ition). th.:it connect, on a con.tinous or inter-mittent basis, to r;hc reactor coolant pressure boandary; *or the steam and fc*.:ti*.:~1ter systcr:is of Pt,"R plants, should b.c designed to the stress lir.1.lts specified in I.B.or II.n. of the Branch Technic<ll Positioi1.
These portions of ;1ir:!:-er.argy fZuid :;y:;te.m p1p1ng shou.ld be provided with pipe ~hip r~straints tl1at are capable of ie~~sting bending acd torsional ~o~ents productd by a postulated piping f~ilure c~ther upstrc.:ir.i or clmmslrca;;1 of the containr:icnt isolation vah*cs.
The restrain~s s'hould b.:?. located rcasonably.clo~c to the containment isolation valves and should be desiGned to withstrind the.loadings
. resulting from a pos:.uia-:;ad p:pi.ng fail;,1~C? beyond these *portions.
of piping so* that neither valve opera~ility nor the lcaktight iritegrity o{ the containaent will be impaired~
Portions of fluid.:;yatem*piping bet~een isolation valyes cif dual barrie~contain~ent structures should also meet the design provisions c! l
~~ove.
In ;tadition, those portions of piping that pass through the containQcnt annulus, and whose postulated f3!1urc ccul~ affc~t
- the' lcaktic;ht integrity of the containment St":'ucture or result* in pressurization of the containcent annulus beyond design limits should be provided with an enclosi_ng protective s tructurc.
For the purpose of establishing the desien paramaters '(i.e.,
pressure, temperature) of the enclosing*~rotcctive structure, a full flow area opening sho~ld bc*.:tssumad in that portion.of pi.ping yithin the enclosinc struct~re takinc into account vent creas, if
- provided,. in the enclosing* struc:ture.
t~11P.re gu<lrd *pipes for individual proccsi pipes a~c used as an enclosing p~o~~ctive structure, such gunrd pipes ~h~uld be desi~nccl to pcet the re-quireme~ts specified in I.B.6 of the Branch Technic.:il Position
- TerminaZ *~1~ds of the piping runs e:-:tendinb beyond these portions of high-energy fbi',i ::y:;:;t;.~ piping should be consiclcr~ci to orisinate at a point adjacent to these required pipe ~hip restraints located inside and. outsidC! containment..
ATTACl!.'IE:;T B DED "rT10:1S Essential S*1:;tt:"'::i '::'1d. CC'.:.;,m:.~1~t!1. Systems and components required to shut dotm the reactor ;:rnd mitis.:itc the consequences of a postulatad piping fai1.urcJ without off-site power.
Fluid S11G t.:':.--:-:.-:;.
H-:'.cJiz and moderate enargy fli.tid :;ystc~:s tba t are subject to the postul.:ition of piping f.'.lilures outside c6nt.:iinmcnc.:i~.:iinst whic~ pro-
- tcction of c:;scmtic.Z :;:..*st~.'71:; c.>:d ccr.roommts is needed.
~
Hir,h-F.ncJ'r.11 :"l:i;".-7 S-.*.-.t.~~:;. Fluid systc::is chat, during 1~01'.":';:::ZZ piant condition:;,
are either in operation or maint~incd prcsstirizcd under conditions where either or both of the following are met::
- a.
maximum operating temperature exceeds' 200°F, or
- b.
maximum operating pressure exceeds 275 psig.
Nodcrc.te-E1iert;11 F'Z1i?:d S:;st::T:is.
Fluid systems that, during nor~ai ;:>la.nt
.conditions, are either in opcraticm or maintained pressurized (abo~e atmospheric,.. pressure) under cond.itions where both of the f ollowinG are met:
- a.
ula."<ixr.U!:l operating temperature is 200°F or less,* and
- b.
- maximum operating pressure is 275 psig or l.ess Norr..al PZr:::!+,
Co1v;,"~t~'<::::::.
Pl.:int operating ccnditions during reactor st~rti;p, operation. at power, hot standby, or r.eactor coo.;I.down to cold shutdown condition.
Upset Plcr:t. Cc1y-?{1;{c1:.;:.
Plant operation conditions during. sys te;;'l transients that may occur with r.icdcrate frequency during* plant service life C1.nd are s.nticipated operational oc~urrcnces, but not during system te$tin~.
Postz~!atcd Fh::7'.11': ;;:'.'1.. *.?111*c!J.
Lonr,itudinal c:nrl circur.1ferential breaks in high-cn*:J1'g~1 fZi,i.i. 3,'f*<;:em pipinr. and through-wall le.:ib1ge. cr.:icks in rr.od.:;pcz;;~
enBrgy ffoid sy:;tcm piping postulated according 'to the provisi.ons of the Branch ~echnic.:il ~ositicn.
Sh and*S11
- Allo*;able stresses at lil.'.lximum.(hot) temperature and allo\\..".:iblc
- stress Fange for thcnr.:il expansion, respectively, as defined in Article NC-3600 of the AS~IB Co<le, S~ction III
- 1-,
\\*...,
I*
- ! 11.. 2 S
- Desisn stress intensity as defined in Article ?IB*J600 of the ASnE Code, m
Section III...
Single 11ct:'.t*c Cc~r:*:f"'?°t Fc.~:zurt.!.
M.'llfunction or loss. of function of a component or. clc.:cLr ic:il or fluid systems.
The failure of.ln.lCtive com-ponent of a fluid system is c9nsidcred to be a l~sd of c~~poncnt function as a result of ccc!1~nical, hydrnulic, pn~u~ntic, br* elcctricul malfunction, but not the loss of compon~nt s~ructural intcGrity.
The direct consequences of a si>:!)~t'.? c~:;-!.vc cc.1po;;.,;nt {a~ Zure arc considered to b!! pilr t of the single failure.
Terminal E>:c3.
E~trcmitics of piping runs that connect to structures, components (e.r,., v.essels, pumps, valves) i-or pipe anchors that act.as rigid constraints to piping thermal expansion.
A branch.~onnection t6 a m3in *pipirig run is a tarr.rinc:.Z end of the brilnch run.
In piping runs which arc maintained pressurized during normal plant co11dition:; for only a portion of the run (i.e~, un to.the first normally closed valve) a te27ninal end of such.runs is the. piping connection to this closed valve.
- .*I*,"' - -*
I I U * ~. *.
An'1lyscs arc rc-qu.i red t.o nssure t li:lt p_ipc mot inn c.:iu!ieJ hy the dyn:lnic
- cf£ cc ts of po~LuL1~cJ cicsii;n. ha!'i:~ l1rcaks will noL ir.i~.ict or *ovcnares~
any st:.:ctures, *s~:~tc::1s l*r cor.ipon**ntr. i;':"lporr.:int to ~:iret'.,* to the extent:
that their s:ifcty flmction i*s imp.1i.rc11 or prccluucd*.
The an.ilysis r.icthods used fihould be adequate co dctcr~ine the rcsulcin~ lo.:i<li~gs in terns of:
- a.
the kinetic C'ncr;;y or ;.ior.ienlu::i inlluced by the impact of t?-:c 'Whippinr.
pipe, if unrestrained, on a protective b.:ir~icr or a co~ponent im?orcant to s.ifcty,
- b.
the dyna::lic 1*c::;po:1s~~ of the rer.tr.aints induc~d ~y the impact and rebound if.:iny, of tile ruptured pipe.
The basis used to determine the t;i.:ir,nitude:- of jet thrust force. as* required in dynaniic analysis should l.n! provid!.!d.
The methods o"f dvn.:ir.iic :rnalysis specified in II and III are acceptable provided the foliowing associated criteria arc met:
I.* Pipe ~1ip Dvn~~ic ~n~lvsis Criteri~
a *. An analysis of the pipe run or branc*h should be performed for each longitudinal' and circu~fercntial p6stulatcd *ruptur~ ~t the design basis break locations.
b *. The loading coridition of a pipe run or branch prior to postulated rupture..:.n t~.-r.*.s of :.rl_::crn.:il pressure, terapcrni:ure, and stress state should be those conditions associated with reactor operatint condition (normal and upset).
- c.
For a circumferential rupture, pipe whip dynamic analysis need only be per formed for t h.'.1 t end (or ends) of the pipe or branch which is connected to a cont.'.l.ineJ fluid energy reservoir havirig a sufficient capacity to develop a jet stream.~
- d.
Dynamic analysis methodi:; used for calc:ul.ltin~ the piping or piping/
restraint system response to the j~~ thrust developed followins *
~osculated rupture ~hould adequ~tel~ account for the effects of:
(1) mass inertia and stiffness properties of the system, (2) impatt and rebound* (if any eff~cts'as permitted by ~aps between piping and restraint)
(3) St.itic 1\\n:il_*~ls :*Incl cl -
- 1 he il't thrust fcir,.-- is rcprc~c11Ll*~I hy
- a conscrv:it
'ly,,mplificd SL.itiC: lo;1<linr;,.* cl. Lill'* r11pt11rcd systcm.i;. ;i11.1ly;:ctl st.:it1c:illy.
/\\n.:llllf>lltit.1tlnn f:1Clor nf J Cilll be usc<l Lo c:.L.il>l i.sh Llic r1.1g11 i Ludc of the (ore 1 nr, (unc ti nil i r tlic piping 01nd rc:-;tr;lint ~yst1:111 remain clnstlc *.
llow~vci, a C:ictor based on selection of :i Ct1nscrvotive v;lluc :is oht.1lncJ liy cu1:1-pari!".on... :ith the f..:tctors tier ivc<.I from rlcr..1 iJ c<l ;1,*namic-Ctn.:ilysis performed. on cornp.Jr.Jble sy:;Lcm:; is.ilso.icccpL.:ible.
111.
i\\cccpl.:1hlc ll*:n.1:nlc,\\n;ilvsis [1:-r 1:nrcstr.1incd ripe \\*.'hin
- a.
Lurnped-rar;:i;;1ctcr An;:ilysis :*lodcl.ls stiltetl in 11.a(]) is acc:eptablc.
- b.
Encq:y-HJlancc An.1lysis ~*:odel
- ns stcited in IL a(2) is acceptnble.
The cnerr,y a;,~;,HbcJ by the pipe Jeformntion tnil)' be deducted from the tot.:il encq;y irnp.:irtcd to -tile system.
- c.
The assur.iptil')n!; used to guide the 1~chanism of pipe m*ovcmcnt should be justified to.b~ conservative.
- d.
The results of.:inalysis should be e:*:prcsscd in terms compatible with the approach uscJ for _vcrifyini:; the design adcquilcy of the imp<lcted structure.
IV.
Flow Thrust Force
- a.
The time function of the thrust force induced by jet flow at the desicn basis pipe bre~k location shoul~ considec:
(1) t~e initial pu°lse, (2) the thrust dip, *and (J) the transient function.*
- b.
A ste<lciy state forcing function can be usecl *... :1en conditions as specified in e below are met.
The fL1nction should have a magnitude not less than T IC KpA where p =system pressure prior to pip~ break.*
A = pipe brc.:ik area, ~nd K a thrust coefficient.
Acceptable K values should not be less Chan.the following:
(a) 1.26 for satu!'ated stc'c::im, ~ater apd steam/water mi:<ture (b).2.00 for subcooled water-nonflash{rig.*
- e c,
A pulse r i sc t not cxccc-*: ing one mill i sccor1... should be usc.d for the initi.11 puise, unless l-.*111*,er crdck 1*rop.1~:ition tir.ics or rupture
~pcninr. tin1l!s c.:in be substantiatcJ by cxperirncnt.'.ll <latn or.Jn<llytic<ll theory *
- d.
The tran:.icnt i\\:1{ *ion shoui.<l be provided ;ind jufiLific<l.
The sh.l[H.'
of the tr;insicnt iunctlon, lV a.()).1bovc, should he rnlnted to the capacity o[ the upstrca~ cn~rgy reservoir, includinG source p~essurc, fluid enthalpy, :rnd the c.:ip.:ibility o[ the tcr.crvoir to suprily high cnerr,y flo:; strc:im to the brc.'.lk nrc.:i for :i r.ic.nific.1nt interv.11.
The shape of the tr.1:isicnt function.;;;ay b.:?
- nocli[~cJ hy con~i.derin~ the break arc:i.1nd the system flo\\..' concJi.tioltS, tlic piiJtllJ:; friction ]ci!"'5CS 1 the flow directional ::b,rngc~, anJ the applic.Jtion of flow liraiting devices.
- c.
1'he jct tl1rust force r.::iy be represented by.'.l stc.1dy state fu!1ction, b above, provided the following conditions are met; (1) The tr~nsient function, IV ~. (3).:ibovc, is monotonically diminishing.
(2) The energy bal.Jnce model or the static: model is use.cl in the analysis.
In the former case, a step function ar.iplified to the
- magnitude as indicated in II.a(2) is acceptable.
(3) The energy approach is U$ed for the impact ~ff ccts of the unrestrained piping.
i I
- ~
(4) limiting'. boL
!ry conditfons.
- e.
The allow.,hlc clcsi~n ~tr:tin Umit for the rcstr:tint sh<"'ulcl not C?xcccu 0.5 ultim.:>.tc uniform r.t.r:tin of t!ic m.1tcrialr. o( the rC'straint,!;.
Thi..!
method of dyn.:imic.:in.1lysis used should be c.:1p.:i1*
.! of"dctenninin:; ti1c inelastic bch.:ivior of piping-rcstr.'.lint system response witi1in these dcsisn limits.
- f.
A 107. incre.:isc of minl.mum specif id design.Yield strringth (Sy)- may be useu in the an.:ilysis to account for str<iil'I rat~ effects.
- g.
Dyn.:imic nn.:ilysisi methods anJ proccLlurcs should consist of:
(1) a rcprcscnt.:itivc matllcm.'.ltic:tl 111odcI *or the pipinc, system or piping/rrstraint system, (2) the annlytical method of *solution selected, (3) solutions for the Most severe response amo?s the design ~asis breaks analyzed, (4) solutions with demonstrable <i~curacy-or justifiable conservatism.
- h.
The extent of mathematical: modeling* and analysis. should be governed by the method of an::ilysis selected among those specified* by these criteria.
II. Acceptable Dynamic Analysis for Restrained Pioincz Svsi::ems
- a.
Acceptable Models for Analysis for AS:1E Class 1, 2 and 3 pipini:; systeons are:
(1) Lumped-Parameter Analysis, Model; Lumped mass points are interconnected by springs to take into ac.count inertia and stiffness effects of the system, and time histories of respdnies arc conputed by numerical integration to account for gaps and inel'astic ef fee ts.
(2) Energy-Bal.:ince Analysis Model; Kinetic energy generated during the first qu.:irter cycle movement of the ruptured pipe as imparted to the piping/restraint system through it:1pact: is converted into equivalent ~train energy.
Deformations of the pipe and th~
restraint are compatible with the l~vel of absorbed energy.
For-applications where pipe rebound 6ay occur upon i~pact on the rest~nint an.:iddition.:il amplification f<ictor of_l.5 shduld be used to establish the m.:ignitude of tile forcing function in order to determine the maximum reaction force of the restr;iint af tcr the first quarter cycl~ of responac.
~mplification f~ctors other tl1an 1.5 ~~-be used if justified by more detailed dynclmic analysis...