ML20087M142
| ML20087M142 | |
| Person / Time | |
|---|---|
| Site: | Point Beach, 05000000 |
| Issue date: | 03/01/1973 |
| From: | Reed G WISCONSIN ELECTRIC POWER CO. |
| To: | Arlotto G US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20087M093 | List: |
| References | |
| FOIA-83-728 NUDOCS 8403290049 | |
| Download: ML20087M142 (40) | |
Text
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- WISCONSIN MICHIGAN POWER COMPANY i
- WISCoNSlN ELECTRIC POWER COMPANY l- A 9 '.
; POINT BEACH nuclear plant posrat noure s%,veh'isconsin saa?%
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} TWo C AEEKS. WIS. Q N
i ~ _ R5 w-i Mr. Guy Arlotto 6-' 1973 Directorate of Regulatory Standanis u,T, E.i@
- p (Bethesda-010) g a[jj?," s U. S. Atomic Energy Comission g Washington, D. C. 20545 N o
Dear ! . . Arlotto:
As follow up to our telecen of Febmary 26, 1973, please find attached information which describes our reactor coolant system leakage monitoring as follows:
- 1. PSNP 3.27, Reactor Coolant System Leakage Detemination
- 2. Two six curve plots chosen at random showing trends for evaluation by operating people.
3 A March 1,1972, l'etter to J. W. Stacey of the ANS subcommittee which describes our reactor coolant system leakage monitoring further. If you have any further Iquestions on our leakage monitoring, Mr. T. J. Rodgers or I would be most happy to oblige. In fact, since Mr. Stacey's ANS subcommittee is being phased out and Mr. Rodgers has been released as a member, he would be willing to expend some effort to orally transfer to you what he would have provided to the ANS subcommittee. Mr. Rodgers can be reached more easily in Milwaukee at 41L-273-1234, Extension 2946, than,at the Point Beach Nuclear Plant. Very truly yours, WISCDNSIN MICHIGAN POWER COMPANY 9
. O' CA$tl Glenn A. Reed Manager - Nuclear Power Division i ktw i
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j PBNP 3.27 Revision 1 .
.7-10-72 t 'l*
REACTOR C00I. ANT SYSTEM LEAKACE DETERMINATION
.J -i 1.0 PURPOSE The purpose of this instruction is to detail the method for following j trends of reactor coolant system leakage and to determine
- quantities, in conformance with Technical Specifications cormitments, Section 15.3.1.D.
;) of first importance is the need to ascertain that there is no " exterior
; wall" leakage from the reactor vessel, reactor system piping, reactor system valve bodies, pressurizer, reactor coola*nt pump bodies, or the
'. reactor coolant system side of the steam generators. Of second.importance is to ascertain that if any leaks occur in gasketed closures or packings cf the reactor coolant system they are well under control with quantities according to Technical Specifications commitments.
It is not the purpose of this instruction to quantitively determine reactor coolant system to other system cross-leakage or flow, such as primary-to-secondary steam genefator tdbe ' leakage (evaluated by Chemistry and Health Physics), or reactor coolant system to component cooling leakage
, (under continuous evaluation by the component cooling radiation monitor) ,
( or reactor coolant system leakage to cennecting systems such as reactor coolant drain or pressurizer bicwdown or charging and volume control. Such uncontrolled leakages as these noted above must remain so small in quantity for reasons of other limits that the leakages are not significant in the first evaluation limit of the , Technical Specifications at 1 gpm. 2.0 METHOD AND RESPONSIBILITY 2.1 As shown in the Technical Specifications Section 15.3.1.D, there are six methods of discovering or evaluating reactor coolant system leakage into the containment. They are as fo11cws: 3 2.1.1 Air particle monitor 2.1.2 Radiogas monitor .
,. 2.1.3 Relative humidity 2.1.4 Sump A drainage
. 2.1.5 Chemistry and Health Physics water balance 2.1.6 In-containment physical inspection
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" .) 2.2 In order to maintain evaluation type surveillance of reactor coolant ,I system leakage, the following observations and actions shall take r c.I place: 1 .
; 2.2.1 During hot pressuri:ed operation, the Control operator ft . shall periodically observe the air particle monitor ,
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reading, the radiogas monitor reading and the relative humidity reading. ,, } 2.2.2 During hot pressurized operation, the " eye ball" average readings or values of the following shall be plotted, if l l available, on a graph once per days 2.2.2.1 Air particle monitor i 2.2.2.2 Radiogas monitor 1 2.2.2.3 Relative humidity l 2.2.2.4 Sump A drainage ] i 2.2.2.5 Chemistry and Health Physics water balance l leakage nue.ber j (, . 2.2.2.6 Service wa'ter temperature .
- 2.2.3 The six line graph shall be reviewed once per day by the i Duty Shift Supervisor '
for Technical Specifications com-p11ance. 1- . 2.2.4 The six line graph shall be reviewed once per week by ,the. j, Duty and Call Superintendent and the 0%ations Superinten-
!. dent.
2.2.5 - A physical inspection inside co#ntainment for leakage eval-uation reasons may be ordered by the Duty Shift Supervisor,
- the Duty and call Superintendent, or the operations Super-intendent, at any time felt necessary.
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- [, 2.2.6 During hot pressurized operation, a physical inspection
/! inside containment shall be made at intervals not greater
, ji than once every two weeks, with time and results noted in
- j the station log.
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- The operations Superintandent shall periodically review the i 2.2.7
- -i primary-to-secondary leakage and determine that when added - '
1 4 to Sump A leakage, the 1 gym figure is not exceeded or that
I additional Technical Specifications evaluations occur as ., ( required. .
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j 3.0 EVAI.UATION
,'ei Scme keys to evaluating in-containment leakage as itemized above are as t j
.,1 follows:
)-j 3.1 A rising air particulate monitoi reading (under steady-state con-
< ditions) can mean an increasing,, leak in the reactor coolant system,. y i1 and, if it is the single lea' ding indicator, may mean the leak is in the liquid phase of the reactor coolant system.
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.i 3.2 A rising radiogas monitor reading (under steady-state conditions) l' can mean an increasing leak in the reactor coolant system, and if it i, i is the single leading indicator may mean the leak is in the gaseous '
;
- phase of clie reactor coolant system such as pressurizar steam space levels.
3.3 A rising relative humidity reading, under steady-state conditions, as the single leading indicator can mean an in-containment leak from . j systems other than the reactor coolant syste=, a reactor coolant
~
system liquid leak, or can zeen an increasing service water system temperature. Relative humidity re.adings shculd not exceed 50% if all in-containment systems are reasonably leaktight.
.3.4 The gallons discharged from Surp A (under steady-state conditiens) i is the principal quantitative indicator and if rising in quantity can mean a leak from in-containment systems er the reactor coolant system.
3.S The water balance calculation by Chemistry and Health Physics and Item 3.4 above, Sump A. drainage, are the bases for correlating
.s quantitively the readings of 3.1, 3.2 and 3.3 above to approximate
- j. gallons per minute. The ccrrelations are important since iters 3.1, 3.2 and 3.3 above are fast indicaters cf a change in leakage.
! 3.6 The service water system tarpcrature is im;crtant to evaluating corrections to trends of Surp A drainage and relative humidity, and
' d a decreasing service uater emperatura can cause a decreasing
- humidity and increasing Surp A drainage.
- Tor cenvenience to the evaluation, Technical specifications Section 14.3.1.D is attached to this instruction ar.d follows.
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Sl y ; Specification:
;l' t 1 1. If leakage of reactor coolant is indicato: to exceed 1 GP:t by the 2
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r,: J neans available such as water inventory balances, monitoring equip-
- t o ment or direct observation, a follov-up evaluation of the safety 6
,i implications shall be initiate'd c's soon as practicable but no later I than vie.hin 4 hours. Any indicated leak shall be considered to be
' a real leak unti.1 it is determined that either (1) : safety problem does not exis't or (2) that the indiented leak cannot be substantiated I by direct observation or otl.er indiention.
- 2. If the indicated leakage is substantiated and is not evaluated as safe or is deternined to exceed 10 GP::, reactor shutdown shall be initiated as soon an practicchie but no Inter than within 216 hours after the lenii was first detected.
- 3. The nature of the leak as voll as the e.asnitude of the leak shall ha considered in the safety [eiraluatien. If plant shutdown is necessary por specification 2 above, the rate of shutdown and the conditions of shutdown shall he determined by the safety evaluation for each case and ,just.ified in vritin; as scan therenfler as practienble. The nafety evaluation shall assure that the exposure of off-sito personnel to radiation fro:s the prinary systen coolant activity is uithin the guidelines of 10CFR20.
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- k. If any ree.ctor coolant leakase exists throu6h a non-isolable fault t. .
1 I ( in a reactor coolant system component (ext' e rior vall of the reactor 2 7 vessel, piping, valve body, pressuri:ct or steca generator head), , the reactor shall be shut down, and cooldovn to the cold shutdown e condition shall be initiated within 2k hours of detection. 1
- 5. The reactor shall not be restarted until the leak is repaired or until the probles is otherwise corrected.
- 6. Uhen the reactor is critical and above 2.5 pover, two reactor coolcat leak detection systems of different operating principles shall be in
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2 operation, wit'h one of the two syste=s sensitive to radioactivity. Che systens sensitive to rsdiocetivity may be out-of-service for k8 hours provided two other ucans cre available to dctcet leakcge. Scsis: Unter inventory balances, =cnitoring equi;=ent, radioactive tracing, boric acid crystalline deposite, and physice,1 inspections can disclose reactor coolant leaks. Any leak of radioackive fluid, whether frem the reacter
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coo 3 snt systc= pri:.ary bounde.ry or not can be a serie.:s problem with respect to in-pla. t rr. dict.etivity conteninttien end cle.t.up or it eculd develop into a still note serious probics; and therefors, first indications of such leakece Uill be followed up as soon es practicable. 1 Every reasonable effort vill be made to reduce reactor coolant lenhage to
.! 2 the lovest possible rate and at least belov 1 gym in order to prevent a large
- lenk from nasking the presence of a snaller Acak. ,dthoush conc leak rates
- 4) :
Tb 15.3.1-12 T/71 k:endraent 2 ,
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-). i . . l . I on the order of I cpm may be tolerub'le frca a dose point of view, espe- ., I j cially if they are to closed syste=s, it must be recccnized that leap.s 1 7 j in the order of dro;:n per =inute through any of the valls of the primary 14 systes could be indicative of :sterials failure such as by stress corrosion h cracking. If depressurization, isolation and/or other safety measures are not taken promptly, these small leaks could develop into much larger leaks, i possibly into a gross pipe rupture. Therefore, the nature of the leak, as
.t vell as the nagnitude of the leakage, must be considered in the safety eval-
. uation. The provision pertaining to a non-isolable fault in a reactor coolant
, system component is not intended to cover steas generator tube Icakages, valve bonnets or packings, instrument fittings or similar primary system boundaries not indicative of najor ec=ponent exterior vall leakage.
1.' hen the source and location of leakage has been identified, the situation can be evaluated to deter =in- if operation can safely continue. This evalu-ation vill be perfo:med by the 'hnaccr's Supervicory Staff
- according to routine established in Section 15.6. finder these conditions, an allovable leakage rate of 10 gyn has been establishtd. This explained leakago rate of 10 gpm is also vell within the capscity of one char-inq pump,and nakeup would be available eve 7 unict the loss of off-cite pavcr condition.
If leahnge is to the contain ent, it =sy be identified by one.or note of the following nethods:
- a. The containment cir particulate monitor is sensitive to leu leak raten.
I The rnte of lenk25c to which the instrument is sensitive is 0.013 gpa uithin twenty .-inutes, ase: e .ing the presence of corrosion product activ-n
, ity.
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'b i . The containment radiegas monitor is less sensitive but can be used as a backup to the air particulate conitor.
- The sensit,1v,ity range of the - l l i instrunent is approxi..stely 2 gps to greater than 1C gp=. 7 i
- c. The hu=idity detector provides a backup to a. and b. The sensitivity range of the instrc=entation is frc approximately 2 gps to 10 gps.
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- 1 d. A leakage detcetion systes which deter:ines leakage losces from vater
'. and steu: syste=s within the contain=ent collects and ce'a sures =oisture , condensed frem the containment at=osphere by cooling coils of the nain .
recirculation units. This syste: provides a dependable and accurate , means of measuring total leakage, including leaks fr=n the cooling coils themselves which are part of the contain=ent boun[ary. Cendensate flows frca approxi=ately 1/2 gp= to 10 gp: can be re sured by this cyste=,
- e. Indication of lechtge frr.: the above sources chall be cause to require a containment entry a ' 'i- '~ct 'n:p::: ion at p: rer Of the reactor coolant'systes. Visual inspection neans, i.e., looking for steam, floor vetnessorboricacidcrystall,{heforations,villbeused. Periodic inspecticns for indications of leakage vithin the containment vill be
. )
ccnducted to enhance etrly detecti:c of probless and to n: cure best on-li.nc re.liabilit.. . If leakage is to another systes, it vill be detected by the plant radiation
.onitors and/or water inventory control.
t References NsCNC Sectica 6.5, 11.2.3 . 15.3.1-lL
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- WISCCNSM MICHIGAN POWEA COLIPANY
. Wl3 CONS:N E'.ECTAIC PCWER COf.19AMY
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POINT. ' a -8EACH nuclear plant gosruovre 3. rwo mess. wiscousiu s.
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! March 1, 1972 ,
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Mr. J. W. Stacey, Section Head
' 1]i Mechanical Engineering Section Yankee Atomic Electric Co.pany '
.; 20 Turnpike Road j Wsatboro, Massachusetts 01501 Dear Jim
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V -- pg g 7 In reply to your letter of February IS,1972, on Reactor Coolant Pressure Boundary Leakage Monitoring, the Point Beach Muclear Plant reactors are two-lcop, PWR, 500 MWe units with Westinghouse as the nuclear steam supply turnkey scpplier and Bechtal Corporation as the architect-engineer for Westinghouse. Unit 1 began cor=ercial service on ::ecember 21, 1970, and has genera ed about 4,300,000,000 k;<h. Uni: : '<as completed and the core loaded in late 1971, but has not pro-d . r! pcwer because of a public interventien. The Point Beach Nuclear Plant units use fiva techniques for primary boundary leakage into contain . ant r.cnitoring. They are as follcust
.t f 1. Containment Relative Humiditv This acnitoring is censidered quite accurate and j capable of detecting leakace from the pri=ary boundary at ratu of ena ep= or loss. Some eval-uation and folicy cf centair_ar.: cooling equip ent i
is nactssary since hun:idity varies wi:h deht idi-ficatica effcets of this squip= ant.
- 2. Contain=ent su=p A Drainaae
; This monitoring is by small calibrated su=p (12 gallons) located at the lowest point inside contain-ment. All floor drains and recirculation cooler drain pan.$ funnel to sump A, and theracy all system leakage or cooler drainage from dehumidification action is quickly collected and accurately measured and discharged to the primary auxiliary building at
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intervals. This monitoring technique is able to detect leakage at rates of 0.1 gym or less, and detection is possible w!. thin a few r.inutes. . , .i
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'I .'< ,qi 7 6a 3. Containment Air Particia Monitor 14 Of This traveling filter paper radioactivity monitoring ?]
unit responds very quickly to .*.eakage but correlation fi to gpm quantity requires comparison to sump A drain-q aga conitoring. Increasing air particle monitor y reading without a corresponding gas monitor reading T' . normally indicates a leak from the liquid phase of the reactor coolant systa=.
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- 4. C'ontainment Gas Monitor
; This' radioactivity monitoring unit responds very
. quickly but correlation to gpm quantity requires com-parison to sump A drainage. Increasing gas monitor
?' readings without a corresponding increase in the air
- particle monitor readings nor= ally indicates a reactor coolant system gaseous phase leak, such as the top of the pressuri:er.
- 5. Watar 3alance Oetartination tiatar balance decerminations are mada by chemistry percennel on a daily basis at : resent. As you can ,
appreciate, the water balance metned is not the cost desirable due to tha cultiplicity of very large tanks and inherent limits on instrumentation accuracy. The water balance cathod becomes very complicated in a large plant sucifKs Point Beach, and will become even ' i
] core complicated when both units are operating. In addition, this method does not distinguish between
" controlled leakage" (chsrein; m.=p seals , sa=,711ng, ote.) .nd "uncontrollad laskage* (valva packings,
'l cracks, ate.). Since the "u . controlled Icakaqs is really tea desired answar une vator balance is o!
ll liedtad value only, t .
; The use of the five techniques or systems above in an appro-d priato fashion allows one to predict what. system in-containment leakage
.]vi is coming from, such as steam, component cooling, etc., and forms the basis for scheduling in-containment inspections at power. Without any Ii unusual indications on leakage, we normally schedule two in-containment -
1 inspections per week. It 'should be noted that for *he most part the ii above techniques are dependent upon the principle d ' closed" . contain-ment operation, which is the basis of operation at Point Beach Nuclear
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[.. Mr. J. U. Stacey March 1, 1972 .. 4 . h The Point Beach Nuclear Plant unita have three techniques for d renitoring prinary-to-secondary steam generator leakage. They are as i-l follows: Q q? Blowdown Radioactivity Monitor 3 1.
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t steam ganarator liquid is continuously renitored for radioactivity in a cor.posite radiation ronitor. In k the event of an increase in activity either steam
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generator sample can be isolated from the monitor.
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3 This monitor is more of a trend indicator than an ab-it solute leakage rate indication since, for the same d leak rate, the activity will change with blowdown rate, primary ecolant activity, etc. aJ.
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.7 2. Air Ziector Monitor The air ejector monitor is prchably the best indicator of prir2ry-to-secondary laak rata although it cannot distinguish bet.ioon steam generators. i11th a knowledge of prirary ecolant qssoons sceivit/ the total 1 rate c:n be calculated. .e find that we can get con-sistant and bel;cvable data a- levels as icw as 10 gallens par day.
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- 3. Sample Radiochemical Analvsis The laboratory analysis of steam generator blowdown samples yields isotopic data which can be used to cal-
, culate leak rates over a certain period of time. In general, however, we rely en the air ejector monitor data and only periodically do we esiculate le:sk rates usin; atesta generator bic dow . analysis rasults. We fin:1 fairly goed correlation between the two.
5 He '.'. ave h:d discussionJ with the AdC about cur in-contairmant leakage conitoring, and these were favorable. The AEC had no suggestions
.. for improvement, and we believe,were surprised at the ability to quickly and accurately monitor in-containment leakage.
-1 1 We have considered the subject of moisture sensitive tape j sonitoring of leakage and find it cannot be as accurate or as quickly
; responsive as combinations of relative humidity, sump drainage, air 1 particle monitor, and gas monitor. Tape also suffers disadvantages in y' reliability, interference with in-service pipe and weld inspections,
. and the impossibility of locating tape at all the places required to de-J.j tact a leak.
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March 1, 1972 .i Mr. J. II. Stacey _..
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.4' All Point Beach Nuclear Plant in-containment leaks thus far 'j have occurred at valve packings and valve body-to-bonnet gasketed 'j flanges.
4 Very truly yours,
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i A FISCONSIN MICHICAN ?OhT.P. COMPANY
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~i Glonn A. Reed Manager - Nuclear Power Division fat .
bec: Mr. Sol Burstein Mr. C. W. Fay Mr. G. A. Reed - Plant: 1.26.1, 1.1.1 9 9 9 4 e 9 4 i.3
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.L am a : . . .m .. . . . .se. .A 5 . . _ _ _ _ _ . _ . _ ._ _ . .. 1_. . 4 .- _._ . . . _ - .y....__ . . _ _ _ . . . _ _ . __ _. .__ . ._ a.. - W, ,,4M , ,'n.- .,A e . Dra,ft %,$ V ?. 4% . a/'4 j ~/q- f3' - ~ ..] __CAF TY GUTM - N - ./. h' .j - REACTOR COOLANT PRESSURE BOUNDARY . LEAKAGE DETECTION SYSTEMS A .- In troduction General Design Criterion 30, " Quality of Reactor Coolant Pressure Boundary," of Appendix A to 10 CFR Fart 50, " General Design Criteria for Nuclear Power Plants ," requires that means be provided for detect-ing and, to the extent practical, identifying the location of the ~ source of reactor coolant leakage. This y guide describes acceptable methods of implementing this requirement with regard to the selection of leakage detection systers for the reactor coolant I .3 I' 3hM/ d ' pressure boundary. [7, B. Discussion ,- The safety significance of leaks from the reactor coolant pressure boundary (RCPB) can vary widely depending on the [nsture) source of the leak as well as the leakage rate and duration. Therefore, the detection and tonitoring of (untintiespeeed] leakage of reactor cool- .h. - . , ant into the containment area is (importsne] necessarv. In most cases , methods for separating the [espected] leakage from (unentie- . , l-i ) @Yl . ,I spated] an identified source from the leakage from an unidentified i a' t, source are necessary to provide prompt and quantitative information .. *u to the operators to permit them to take immediate corrective action s y: - ' r, . a ' ,- .$ , } 'p l* I ;;' "# '*y.'. l W ;n. mk) . ...s.e, .- i. J.4 - a% ~ -r:
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- f. ! should a leak be detrimental to the safety of the facility. Identi-
.'.t .. . . , K--j fied leaksee is - (1) leakane into closed systers , such as num seal aq ;i- -l. ; or valve packine leaks that are captured, flow metered and conducted , ' , ~ ,. ., f ..: T to a sumo or collectine tank, or (2) leakare into the containment l . atmose.her'e from sources that are both sn_ ecifically located and known not to either interfere with the coeration of unidentified leakage r.onitoring systers nor to be from a flaw in the RCPB. Unidentified 1 leakage is all other leakaces. l l i Leakare Seoaration l l A limited amount of leakage is expected from the RCPB and front auxiliary systers within the containment such as from valve stem packing glands, cf.rculating pump shaf t seals , and other equip =ent that cannot practically be made 100% leaktight. The reactor vessel closure seals and safety and: relief valves [neet=eily] should not . :, .I . A)& leak: hah .. .a g. however, if leakage occurs via these paths or via pump [e] and , valve seals , it should be detectable and collectable and,., to the extent [penetteebie] oractical, isolated from the contain=ent atmosphere so as ~ not to mask any potentially serious leak should it occur. Thes e . ,6 leakages are known as " identified leakage' and should be piped to n tanks or sumps so that the [neeme1] flow rate can be established ..q u:; .g p y . . ' T."- .] and monitored during plant operation. . .h.3,3s - 9 e.% .'l f@. e4.4 \ ': s c.j', -
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? C;'.$Nhd , .hr ' =, ?N&.3e. * : t ;. .. . . ~ h - SU-[,h, ..,! . E c i-;?; i) : e , , - s.o . - .m *r'., y Q - '{; :' , l N.C , atmr-cc.LLeaeed leakage to the containment [eree] atmosphere from IF c. -@. i m 5 < " N. . . sources such as valve [s] [er-leskage-from-ebner-e1-eenses-seeh-es y- fe.Q j [ : , .] ehreegh-flaws-in-the-REpB-et-ocher-system-bemdeeses] and stem pack-B .- P .4 g N r' ing glands and other sources that are not collected increases the g 3 I , humidity 'of the containment. [ en d-co nd e ns es-e et-en-cel d-co mp o ne n ts F : n end-in-the-eenesine.ene-air-eeelees r ] The mois ture removed f rom the it atmosphere by air coolers together with any associated liquid leakage ! to the containmen is known as " unidentified leakage" and should be e E collected in tanks or su=ps where the [ner-e-1] flow rate can be b established and monitored during plant operation. A small amount E $ of unidentified leakage. nav be impractical to eliminate , but it I = should [Ee-is-4=peteent-thee-the-nereal-enidentified-leshese] be Er reduced to a small flow rate, preferably less than one gallon per minute (gpm), to permit the [unideneffied] leakage detection systems ~ h; k to detect positively and rapidly a small increase in flow rate. Thus ir-g g a small unidentified leakage rate that is of concern will not be , = t = masked by a [lerge-neeme4] larner accentable identified leakage rate. E ' E E -i
- Substantial _intersystem leakage from the RCPB to other systers across
~ i passive barriers or valves is [ner-eHy] not expected. However, g m . = should such leakage occur, it may not be detectable through the E - . ..~i :- above-mentioned [eeHecting] detection systems , and other alarm and M ,. . i .; ~ ., , : j detection cethods snould be ecployed. For exarole, steam generator ,i E" _ , i 'l g td f +. . --E y "A . ,Y'.'.,' y L , ., 2,. E* .. . . ~ .
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f IT,d . r N..%~..>2.,n 1 jen j_l .m c ~ i-Q*.7 , . . . gc . 4._j t , . ' .- :;f 1 -- a u ..r-. '6 -Q 1eakage in pressurized water reactors (Pt&.'s) should be conitored to n ;;n.,;., n,. ) d.' L'fr@.3 .. detect tube or tube sheet leaks. , __ ;< :r, s 7 ; 5j]
- i -Z'II Acceptable Detection Methods
, ' .n..) . t..,;f, < 9 .' Q Although monitoring of both identified and unidentified leakage is 9:)- dh, impo rtan t, the following descriptions and requirements are intended .. ;,[ (pdmadly] for systems to detect and aid in locating unidentified leakage. > In addition to monitoring flow rate changes to tanks and su=ps, for liquid collection, other methods should be included to indicate when coolant is released to the containment atmosphere. For examole, such-additional detection methods would indicate and/or monitor changes in:
- a. airborne particulate radioactivity,
- b. airborne gaseous radioaci:1vity,
- c. containment atmosphere humidity, ,
r
- d. containment atmosphere pressure and temperature,
- e. condensate flow rate from air coolers.
Since intersystem leakage does not release reactor coolant to the containment atmosphere, detection methods should include monitoring ._y of water radioactivity in the connected syst'eus where the system , flows through the containment boundarv, and airborne radioactivity t . _.f. g where such systems are vented outside the containment boundarv.
- P Another important method of obtaining indications of' uncontrolled 4
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.- . ~ * <4,., .: 3. , o.. y'~.r i -.. -e -+' , . . y a.' 'y. . _ - s; ,3- ;. , , ) ' - r a **T + a *s,t, Q 4 . ...pw - , m W +ww , % .h a,- ...as" % e 4 e j d.^ :;QQ.;\lll l$,f-h'.&&hhyh-jffgh,0 fh'QFj.k['QY'.h.;[y,* glf-h'lfh&?.8I .-_. y.- , , . t .m y . u ne.dg3 . e+2.Weil ' ,; ?.-] . .n . a : O .n . , l ,n. t: .~ a: - 5- - , .l. . , e.fl ,3' .i , 'es j4 .1 or undesirable intersystem flow would be the use of a water inventory . .b -jj .1 balance, designed to provide appropriate information such as abnormal N?T i. - 4 water levels in tanks andAwater flow rates. MN , c ;e.c'm. 7~./ -r... . 'y.s9 .'.].4 Potential discharges from closed safety and relief valves [sheeld ^ . e '::~* . . l,*) Vf'^JJ neraal-ly-be] are usually piped to tanks or water pools and considered * ,z 2 . 1. .< A m) pe.rt of (ehe-petentisi) identified leakage. Temperature sensors in .j . the discharge path of sr.fety and relief valves or flow caters in the leak-off lines would provide an acceptable method of signaling stall leakage from these valves. I. While the above-mentioned leakage detection systems [ere-eresene-ly acceptseie] reflect the nresent state of technoloev, it is recognized _ } th'at other detection methods may be developed and used in order to obtain operating experience with them. Among such methods are sonic ~l indicators @ " k ...J -h-- . . ; and moisture sensitive tapes 'q applied to RCPB component parts. The development and use of improved . . , methods o.f leak detection [is] are encouraged. ' 29 . ; It is not required that all of the above-mentioned leakage detection ~i , methods or systems b3 employed in a specific nuclear power plant. t ..,g-l , However, since the nethods differ in sensitivity and response time, ,; 'W :.g; r prudent selection of detection methods should include sufficient i v,.f. -. '. i , . . ~ , ,- systees to assure effective monitoring during periods when some , -'. O -3 detection systems may be ineffective - or inoperable. Some of these p/ S t o I - s a e .e . - ee m ereen ew . ._ 9 N epeem 2 e* **** ; gen e r , p ,,aisepow w .pe us4, gggge e t * ** g ge,e.e. A.+. er e* * * * , * ***EP* 9, ** ** $ ** *** e {
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- jgt .
that (a-need-fer] closer exacination of other detection syste=s is g-.Mt
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't, ',% necessary to determine the extent of any corrective action that may l ai4;il be required. l , *1 . I - 5 :; , . ,1 -c) Detector Sensitivity A basic requirement of leakage detection systems is an ability to detect significant RCPB degradation as soon af ter cccurrence as (practiesble] oractical to minimize the potential for a gross bound- , ary failure. It is possible that some cracks might develop and pene-e . trate the RCPB wall, exhibit very slow growth --O: " ,. ....__'J; ~ n d.s '^^-- ' -- -4 afford ample time for a safe and orderly plant shutdown after a leak is detected. On the other hand, leakage such . as that resulting from (tmidentified-leskege-such-se-eenid-be-eaused , ~. + w .. ,' .i by] stress-assisted corrosion in stainless steel or from a flaw at a W <;. + "'--'q high fatigue point in the RCPB would demand rapid detection and
- l. ' probable plant shutdown. (as-seen-es pessfeie] Therefore, an early
,T ;, , ' warning signal.is necessary to permit proper evaluation of all M taidentified leakage. .4. ,rv._ Industry practice has shown that water flow rate changes of from 0.5 ' -/. 4. ] . . ;};g .] to 1.0 gpm 'can readily be detected in containment sumps by monitoring
- r.;;.VM
, . ..; s '-ne::,. .q changes in sumo water level, in fl.ow rate (e], or in the operating - ~ . + : . frequency of punps. Sumps and tanks used to collect taidentified ,y. Ra.:' # ,1;. - , (.,:f.*. f. '.?: -ws*.. e. : . ',*i ;t ..,'u. + . t a* c - M , 4 ' :t.' 4 s 4 '.s ' g a l;;};'; .l;,' l,,y ~~~<._;~*7-~- -~.ra. _ - r ---~ .,-- :- ' L. ' ' ~ Y '. ~2 ~' y? *73_.'*:= ' K. }Q~5;.~~ Q z. , "?1 'l~5';l Q & *' ' ' ;a; 4 '4. . / ;- r- . __ ; ' -g- ,'; ~ ' %. L : ,. ^ W.-' h * . >; ~ g.: _- - , '<. '- _ y.i ' s 'W - 4 - t. , ~ -. .: ,.=.- b Y5. SY5
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'9:';rr::y' ..L, .. . .. Dt J;~., x:V U' ! . ) M. c: ;4;,,>/M.d 7 MN .w n n - ).miy,N leakage and air cooler condensate should be instrumented to alarm 4,tfi.? ew
- - :y4
'd. nA W .p:Wl/,j for increases of from 0.5 to 1.0 gpet in the normal flow rates. This . v, q?j.c.mA 39 :yrg4 sensitivity would provide an acegptable performance for detecting i 1A.fJ.9 ID A W% Ng increases in unidentified liquid leakage by this method. Wit d' 'S .':~ f%s An increase in humiditv of the [nerma1] containment atmosphere Cidvdy 9,. ; . , . . . . .. . .].ji[ .O.j [ humidity] would indicate release of water vapor to the containment.
- 2. ; . .s. .. g
+- .d.g. @ ~ 4M. . Dew point temperature n:easurements can be used to conitor humidity levels of the containment atmeschere [ ate]. A l' increase in dew point is well within the sensitivity range capability of available L_' ~ : n. ; .- - ' instruments. Since the humidity level is influenced by several fac- .y 3 "- tors, a quantitative evaluation of an indicated leakage rate may be -o . .
- auestionable and should be compared to observed increases in liquid
, flow [ee] from suups and condensate flow from air coolers. Humidity L . .: .. , '[ level monitoring is considered most useful as an alarm or indirect m . .? ' d , m. indicating device to alert the coerator to a ootential orablem. 'j.w 4 ~ . . < , Reactor coolant normally contains sources of radiation which, when
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,jy '; . released to the' containment (eves], .can be detected by the monitoring 7,,/C.. ., ..: sys tems . However, reactor coolant radioactivity should be low during " *N, [%1 gj,gg tuitial reactor startup and for a few weeks thereaf ter until activated @aFy,;l5 de. corrosion products have been formed and fission products may be .,p.w ~j ..W .'.}.j cg$.], available from failed fuel elements : during this period, [redteesen] .wJ fjti. '.c; -- radioactivity monitoring instruments may be of limited value in v%,wx... . .. ,c:.;cis . QN$Qj} a&>j'M LQ , v* e.g~ . j
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k u, i {c hW[Q % . _ . , . . . . . , . . - -. - . . .-........u. ' ... ,,-.- _ ,;3[f. ", t, * '* $. Y- ' * . .. - "' $ +*' 'th . .. $[ ' $ b',. ..h'", 3 f.".'.'.Ni, y *V, c'c ; - T .;> . ^ P k % ' *, ; . ' & ,- ).hkM~ -. hh. .@.Mur{.M4t* M$;,.(x,E IM.'g* ~ ' ~ ' ' Md1.[ Y ^N ' ' ?N NN hh'ifthikk-p)] 5' fj $$h..$I,ff.h hhhhhhbk'2fhkk &@h . i .m -Nkdkh ' :.,w , ". .?4 .,d. . ..;*i'2..4 , c ***p .,, ,;f *r g . h) . - ,- ~@g>%,:. Ui y providing an early warning for very small leaks in the RCPB. Ins tru-m;9e. h -9 uCi/co (setivity] radioactivity for air BN>M.m =ent sensitivic[y]ies of 10 ~ S.9.pd #IW!ih particulate monitoring and of 10N pCi/cc (eetivity] radioactivity ' *? @ sa
- . > r:d for radiogas monitoring are practical for these leakage detection M.wh eq -,--
. *: -lf f., systems. Radioactivity monitoring systems should be included for '..- X. " i. e . ; ;Q;, every plant (especially particulate activity monitoring) because of a Y [the] their sensitivity and rapid response [and-ability-te-preteren-d eis11y-indsestel t_o leaks from the RCP3. Air tecperature and pressure monitoring methods may also be used to ', infer RCPB leakage to the containment. Containment temperature and pressure fluctuate slightly during plant operation, but a rise above the nor= ally indicated range of values may indicate RCPB leakage into , the containment. The (sensiesvity] accuracy and relevance of tempera-f' ture and pressure measuremdnts is a function of containment free ; volume and detector location. Alarm signals from these instruments <,'1 . [are-primarily] can be valuable in recognizing rapid and sizable energy releases to the containment. 9 ; .l,-j While the concern about instrument sensitivity apolies to the lower X , ' ~ 7 l' range of service for which the instruments are selected, the uoper '*7 r . ..i U instrument range limits should be established to prevent exceeding c3'. p;~r;nw w@{m * - ' / S .e;s. ws ., the saturation limits o f instruments . thus makine them useless as J%;avM . s.s.~ MSf$2 indicators of containment conditions. '?~9.%by; .> n .t L 05M,[! s .pse . ,,. Ac. ,1~. ' Wc .S.. ,/.1 Q. . - 4 s ';a &. gd %h= . .,, . . . s... -, .. '. ' . . . . . , , ,~ . h-ldi(.'- ac-h*% . %n . % 14 $<l.4,1g'~ % Q .m y w. . e 4 % - .; 3;-%~;p. }}Q5*l*yj(t?Q%).pllp$y?,sugg,.W/.k.Qp .fg fy#C[@fgy{.Q;q ' O .f Q#;* J ';.g. ,%p@e v@.m , ,N . . .g q. _ ,_ , . - < . x, - *b * . _ . _ . _ , - , - . - . . - ;v.- .. ,: :'- - . : - :. r.s -e 4 . .pl #, 4 " .'m,,. : v r: G+$i.- %'* .u.d% , g*"*- 2.::.- ,O . *
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~ ~.,,,t , .. .,. -p- ~ : 1 .g \ .r l .e[M9F Detector I'esnonse Tine < . l. , '~ . 4: . Edh The need to evaluate the severity of an alarm or indication .is d M$d. p 4.,i h' * ,. important to the operators, and the, ability to compare with indica- , 7;g - ' , j '_ Y. } tions from other systens is necessary. The system response time , .; . -1 ,. .g should therefore be included in the functienal requirements for ,1 ; leakage detection systems. Except for the limitations during the i - initial few weeks of plant operationh-when-the-reseter-eeetent-eay not-centain-setiarated-terresten preducts-ee-fissien producis-from failed-fuel ' lements-] as discussed ereviouslv , all detector systec:s should respond to a one gpm, or its equivalent, leakage increase in one hour or less. Multiple instrument locations in monitored areas should be utilized if necessary to assure that the transport delay time of the leakage effluent from its source to the detector or instrument location will yield an acceptable overall response time. ~ [ Multiple-senser-leestiens-ss-sise] A useful technique in identi- _:/ 1 fying the general location of a leakage area [and-this] is the placing of several sensors within the containment area and observeh4 J j differences in rescoase from the sensors , and this technique should
- iI be used {es-necessary] to satisfy this requirement of General Design i
Criterion 30. t '$ Qf.d M; (MQ..q u ,g , In analv:ing the sensitivity of leak detection systems using airborne ' LW spr *. u..C,t particulate or esseous r'adioactivit4, a realistic orimarv coolant . a ..s:w I M , s ,: r,y *f g , *. I
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-bw :: , c ': , " ,- - m ...~N .- w.*- ".~ . 1 ,$k l.@:g* s ' $'. . N$$'NY0 YY hkY$sY$.YNY$$hYhhi,,:.,.l$:=$55;Ehy' $$r hhkkh ' u \ ..vv '.c .c. , . . . . : 1 ' .L; . - + <. . ,pn. .y :. . . rp. :ic i G. <<y m,I * ;.c. . ;;s , .. - ..;~2,~ * .. ....: r. .". s , 9:PN.".1- radioactiviev concentration assumstion should be used. The exoected il:.lQ '.^ ;;1,4."64 values used in the olant environmental recort would be accentable. ew ' m,. g :) e .s ;:- ;i. q . ..g. n 'g'1lw; 1 Signal Correla' tion and Calibration A '*U It is irportant to be able to associate a signal or indication of a 2 change in the normal operating conditions with a quantitative leakage '. flow (in spe] rate. Except for flow rate or level change measure-t ments fr a tanks, sumps or pumps , signals from other leakage detec-tion systems do not provide information readily convertible to a coeren denominator. Approximate relationships converting these . signals to units of water flow should be formulated to assist -the operator in interpreting signals . Since operating conditions may .1 influence some of the [cenveresng] conversion procedures , [these] o - .': d L ~ ,] the procedures should be ch:::dgd g;.;d;d during such periods. . To assure the continued reliability of the leakage detection systems, -"~' the equipment should comply with paragraph 4.10 of IEEE Std. 279-1971,1/ for tests and calibration. ggggg, Seismic Oualification g j Since nuclear power plants, - 4 ---d-! - E ' **a"- i;. e md gggq' '+3 af,ter h earthquakes , it is prudent to require the N OM% $ : 5Y d.,5.$. s. . [- Copies of IEEE Std. 279-1971, "IEEE S tandard: Criteria fo 4:;;pj Pro tection S: s ters for Nuclear ' Potter Generating S tations ,".rmay F' Y t . be obtained from the Institute of Electrical and Electronics l " $[5V ,t -'E Engineers ,1.'nited Engineering Center, 345 East 47th S treet , New York, N. Y. 10017. l . 'N , t . . I ..e : g q . hl .et.m;]- ]=7 , Y$5C: . . w :r. :.QWSN.':b1g . ; ;me.. .,:..)h.%n&... +3 9 .k.v.m g:n M*W2G %.f.'%.fid.qh%f.g%y;n;,Mh{.&x;i??q&..w mp . k3 %.g $'T?~ - 5 .w -.7. > .;c.y+3gggm;,.,.:..p;. .ggpgg.z::.g::;.. g .. , $ ni phh.h.{fffjf{3g{ *y.+=., .m,...,e._, . ,, , b, h Nbs'hNS,,.,,hhblMNkfhhf f k$k E l 2nt;.3 ' . ll.iy . . .+ g . v 4 m : st - V. j 'q.pG:.1 l, 1 i. .. .$. . . .s. j . l' . 11 - I.
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If I M M. . > ~.;I.3 leakage detection systets to function under the sare conditions. 'I?fh5I a seismic event (equal] cocoarable to' a safe shutdown earthquake (SSE) '/,i@;r.f'f i ..r 9 . .. ..4 -.V'1 occurs, it would be important for the operator to assess the condition ~.' '- ~! ~.3 within the containment (merel quickly. The proper functioning of at ' 7 _ ?.) ' " least one leakage detection system would assist in evaluating the ! a seriousness of the ccndition within the containment in the event a leakage has developed in the RCF3. 'Ihe airborne particulate radio-activity monitoring equipment E*: rasuLeed=for--a.11' 9&_44 has the : *: y, . .g . yu - .a w.p .r . n - / ', L . desirable sensitivity to ind'i'idts'R'CPB 'leaGee'.M ib dorp'onents w y .. . -... :.! u u.. ..~. . . . . , V. v ..:- . _ ,should be qualified (as-seismie-Einss-E-equipeene] to function throuch a SSE. C. Regulatorv Position
- The source of reactor coolant leakare should be identifiable to the
$ extent oractical. Reactor colant pressure boundary leakage detec-tion and (centre 1] collection systens should be selseted and designed ) to include the following:
- 1. Leakage to 'the primary reactor containment from (espected-leaksige c pathe-that-havee' een-entiespeted-end-4dentified] identified
'A sources should be collected or otherwise isolated so that: . :, , .. z, '$'[.$k.djl (a) [it-is-separated-free-wtidentified-leekages--sad] the flow -;m.3: .;a rates are monitored senaratelv from unidentified leakare, . _. _.C y .s.i . . u.a... .y ,; -t' .1 and .g .3 h D. ., yd (b ) ' the total flow rate (s] can be established and ronitored. . f c , .: .i "dl 1 + .r;:n r r ..e... .a.s , . > 1 . . d * " ' fg _q p ? * .
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.Km;-:) - e air.S - - - - - - .. h.. Jg%pwy g 2* [Efquid] pakage to the primary reactor containment from [leakaze . m- w9 '4r, 4 paths] unf dentified sources [that-have-nee-been-entiespated-er $hMI] scW identified] should be collec.ted. [te] and the [eseent-practiesMe g,-g,y gs and-its] flow rate [esesMished-end] conitored with an accuracy ,:-h.c. '.a. .Q.
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~,w .e. , of one gallon per minute (gpm) or [less] better.
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-J- . .:1 . . ,Q. ".. 3. (:Ehe-eenditsens-ef-the-containment-stmesphere should-be-eenstered ,'.Jr. - ;-...?l iI for-ehanges-in-sp.* tepriate parsmecers-seieeted-free-the-felle 'ing 3 i b}-steberne-partteniace-esdiesetivity r ' s (b}--sieberne gsseous-radiesetsvityy " 'j fe}--humsdityy ~ y fd}--pressure-and-temperaturev } f e}-eendens at e-fiew-rate-free-air-ceekers r ] , .- i At least three secarate detection methods should be emeloved and two of these methods should be 1) sume level and flow conitoring YET , ,1 and 2) airborne particulate radioactivity monitorine. The third ,.s *? o .: method may be selected from the followine: ,~ (a) monitorine of condensate flow rate from air coolers, 4 + . . . (b) monitorine of airborne easeous ' radioactivitv. T:1. 4
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w.:,w .* . g ,.1 w i ;;.> Humiditv, teceerature or oressure monitoring of the containment 4 9 ,t g:: % .g:f:j _ atmos phera should be considered as alar-s or indirect indication n-Sh..s. e ,? of leakage to the containment. ayA~r: . .]h,$,y15.$ . l , = Q.'.$ ,;} ; i ,N, .*iCf' ; ~.'w,- , " !. .h] l .s.m ,. l .F y , 1 t y,y,5 , ' %}llj - .~ Q U r ? 3.'3 6' *A% . . ', i I .'.-*~~"~...y' ; t , ; f. , - ,":7.'[,' ' E((.~ 3. :I.' *'%..!ae) .,. 5, Sf.'. .~. ... .- -. " ' e, , '. . , . i + a ;j; *,e ,Y, , ' g* . . .*** , *. .- lN .* f- *. k$ r, *; .? '.h - .', ( ' f?, , - .an.-...-....- . T _ - - ~ ~
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.,. : u n .C og y'., :,.$ . .~4 s , f.:c . '. . - . ~,.w : n . ; qp :.; .. sf-A+'.* v ..'3 Provisions should be made to monitor systers connected to the T .n;.:r OR.
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.f cq 7,a . . h usa 5 j' , .j 'i.M. r :v;ii radioactivity monitoring and* indicators to show abnornal water .. .t f.::a. % '.' q1 levels or flow in the affected area. #. y .I ,".1 ( S v-A-tet st-o f-se-less e--3-s e p sente- det e ctie n-me t he ds-f a r-unid enti fie d '[ 1eakage-sh e uld-b e-e mplo y ed-end-e ne-e f-th es e- me tho ds-s h ould-b e-fp t redie setive-particulate-eenit ers**.tv ] [6v]5. The sensitivity and response ti=e of each leakage detection system in regulatorv cosition 3.0 above employed for unidentified leakage should be adequate to detect a leakage rate, or its equivalent, of one gpm in less than one hour. [h ] 6_., 'Ihe leakage detection systems should be capable of perfor=ing ~ ' their functions following seismic events that do not require plan't shutdown. [Eeepenents-feel _The airborne particulate radioactivity monitoring system should {be-seiseie-Gete;ety-irl remain functier.al when subjected to a SSE. (Gr]L Indicators [ee] and alarms for each leaka'ge detection system .-- ] :j should be provided in the main control room. Procedures for $..' converting.various indications to a common leakage equivalent (s] }* ?"1 !*]1 [in- -m] should be available to the operators e & & & f' ,)- y l 5$'! -v : ,1%f .5 :lJ. 4& .u . ---- - m. - l s.nould account fo r .4%-inde Aten & n endent .'r. .... w. . ; < . y
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varin a les. ---M~m. . ;;'", %pt-nT 2,.g,,i 4 2M'.} ... W w.w ' 3 8 M 9. 1: 'O!,'f'^ *. l'$ C . 't .A&'?,~ $ .l ,.[.. *f.V . .y . ..ws".M .; s. - ' .. ' . -Q. .,3. .'- c .+. . ...v. . ..: s 4 . . " 7' < 'W"' 4 ]~"7 5.i . f*x, ,s:. . .g +&F%.P. . ..5 . . . - 4 ;_ ,;fd..f.N.4y 'M ,.. y.c,,-. * . 3,f;, .. ( s - ;.s _. . ;. . yo ^ ..r ,,.- " - y# -Q,/.E4-M /-? . . ' 'f.i ymf.2 ' - **- . a %'., e. :t . : ' .s . . ' y * -( ,,, s a .4 y ,,. .. i.* ,, . . 4. - - ~ . . . . . . . , u..-_. .. .,7_.,,. . _ _ _ . , , _ _ , P, -.A - ~ * *C $. '. . , - Ef'.*7 M . --m---====-r*--- g . - "[+* ...*8 #. g , . . g.. . $5?$$$$55k"IM ,$. $$!h" ,.p .$$h.$f$.h. h ~ -. .. .\ -}Q'hhh fi{g .. - f'"*%.Y,!'j*0$!$$NE$'$. $5 . .. y .. . . e w.. . es.,.u. 2 - - ,: - u- . . . . s u .. 2 . . ,, .*4 > *. v~ ,. _ u . . * . 14 .%.s a ' .,. > .. / :* b. < .e , . o.m .N.'. [97Q. The leakage detection syste:rs should be equipped with provisions , w.s..v]o.T {'} ~. ! to readily permit testing for operability and calibration during l ,,'. ?; }%.3 .J-Pl ant operation. . F:r.'t <. ,.J ' ~e. .,. . ,s n.v.: %, r. :. 11fj I-197 l9.. The technical specifications should include the [14mitatien-te] .Z ;" -! limiting conditions for identified and unidentified leakage and ; address the availability of various types of instruments to assure . adequate coverage at all times. ~ -- - - - . ____ *~ s4 O + LL ;; . , * ; r ,. .. , ,/ v b. 4.Z. .x.'& ~. I
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^((YEk . .a fWtteb/ to. Ch<~ W b , 3) } -- ..;f f* !j-ji . . j . ] & kkj ${ , OU,, ; Q (C .'.**. % :- . y l $:u b . ' ' E ,.1 l. N ' S,s, .3i - o REGULATORY GUIDE t-IB5 . ' y. 4 - < ~.;; i }) , $ REACTOR COOLANT PRESSURE BOUNDARY . . . 3 1_k3j . Mt ' LEAKAGE DETECTION SYSTEMS .- -i 4 3. d .).,. A. Introduction .~ <- General Design Criterion 30, " Quality of Reactor Coolant Pressure Boundary," of Appendix A to 10 CFR Part 50, " General Design Criteria for Nuclear Power Plants," requires that means be provided for detect-ing and, to the extent practical, identifying the location of the , source of reactor coolant leakage. This guida describes acceptable methods of implementing this requirement with regard to the selec-tion of leakage detection systems for the reactor coolant pressure -: 4ethe(, boundary. This guide applies to light water greactors. B. Discussion i ~ ,^' The safety significance of leaks from the reactor coolant pressure ..'." bomdary (RCPB) can vary widely depending on the source of the leak V as well as the. leakage rate and duration. 'Iherefore, the detection ,j and monitoring of leakage of reactor coolant into the containment area is necessary. In acet cases, methods for separating the < .',# c- ,' j 4, ;; leakage from an identified source from the leakage from an miden- . .g. > a a L;;6.'{;a yy tified source are necessary to provide prompt and quantitative , M.. i.i.m? . , 7.-p..*a .; jf . information to the operators to permit them to taka i===diate ! M.2.i.i1 1?;y[1.'.,a corrective action should a leak be detrimental to the safety of
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. l. . ..$.,p:.~.f.,X. , a $. ,- M.g-Q t 5.u , + f.,b; b d M',.5!?. O'. ;. C+ .4 g - . e. a. .q -- a,A. ey, a .r.,.f' :W: g ,e ^ the facility. Identified leakage ist (1) leakage into closed ,- l ' ! ~ . a . ; ,t systems, such as pump seal or valve, packing leaks that are captured,
- u.y . . s
,ws ~ .97:' flow metered and conducted to a, sump or collecting tank, or (2) leak- ...9 5: a age into the containment atmosphere from sources that are both N,, til4s,4 mef Iv V b(I specifically located and known --- t- "'-- interfere with the et .uof " !. operation of midentified leakage monitoring systems mer to be from a flaw in the RCPB. Unidentified leakage is all other leakages. Leakage Separation A limited amount of leakage is expected from the RCPB and from 1 auxiliary systems within the containment such as from valve stem l packing glands, circulating pump shaf t seals, and other equipment that cannot practically be made 100% leaktight. The reactor vessel closure seals and safety and relief valves should not leak signif-icantly; however, if leakaiga occurs via these paths or via pump and ] valve seals , it should be detectable and collectable and, to the ' .) extent practical, isolated from the containment atmosphere so as
- z. , :.
** not to mask any potentially serious leak should it occur. These f ~ ." [ . J 1eakages are known as " identified leakage" and should be piped to c, tanks or sumps so that the flow rate can be established and monitored .. , during pint operation. ,, n2 . ' J., M.S .
- 3. .e . '. .4 Uncollected leakage to the containment atmosphere from sources such
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. , . ..;,%,- (?y: yg . ,r. 5.,lp . . 5.}. 9 qw . 12 ,b.%' ;.",t.NM./Nd '*c;* . .A ~*iT* ),'.ik +.,,,.. , ,.,k, 4f-hk ~ ', ik-h$. , .' f/d? , ..MhN '[N_.5;;[iiErhkb ..m - ! - $f$- - '}h_$h[^ i ;;ww.,N: . Ab : .]A m:a a . ^ ':sj.y ,j , x.;,.f; . l: 3 i .. , 3 ;-vd'i. V.! , collected increases the humidity of the containment. 'Ihe moisture 3.%f 1s .i , l ~' N g renoved from the atmosphere by air coolers together with any ; il U 5'l . associated liquid leakage to the- containment is known as "tmidentified q ,. [ 7j leakage" and should be collected in tanks or sungs where the flow . A rata can be established and monitored during plant operation. A , , small amount of smidentified leakage may be impractical to eliminate, but it should be reduced to a small flow rate, preferably less than one gallon per minute (gpm), to permit the leakage detection systems to detect positively and rapidly a small increase in flow rate. "Ih us a small unidentified leakage rate that is of concern will not be masked by a larger acceptable identified leakage race. . Substantial intersystem leakage from the RCPB to othe.r systems across passive barriers or valves is not expected. However, should such leakage occur, it may not be detectable through the above-mentioned -q' ? ^ , detection systems, and other alarm and detection methods should be employed. For example, steam generator leakage in pressurized water reactors (PWR's) should be monitored to detect tube or tube sheet I leaks. .g '.- Accaptable Detection Methods
- 1.
I .: ! a.; J ; Although monitoring of both identified ar.d smidentified leakage is ~* ,d , ,. ,: di important, t f:1 in f::r -i;:L c;;_L _ . . ... int re:d l ~ 1;j f;;ne n w J,.an =fr" h t~-c;2. h.:isie12 % . , .u^ M .,4- ' h Pj , y g, w.w. 4 % /mk M ]jkj m aapM4 de lu k ~ M - + :' .f... .'_ . ._ . v: - -~.;c .a. ;. ., = ,;; .. ..
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. u o f:Q* .?e ; 1 - 4- _ . :. c.5 ) .a ?Hi . : . 4.. . > In addition to monitoring flow race changes to tanks and sumps for V .%s ;:. pd [,hh;p liquid collection, other methods should be included to indicate when ad M
- u. ,s;:. .t Mug u W1 coolant is released to the containment atmosphere. For example, ed n.ryCC.
,.. m.! ..t M g additional detection methods would indicate and/or monitor changes in: -3. y & sfhjdj a.. airborne particulate radioactivity, - . a .9 ' b. airborne gaseous radioactivity, . . $,d ' .- c. contain==nt atmosphere humidity,
- d. containment atmosphere pressure and temperature,
- e. condensate flow race from air coolers.
Since intersystem leakage does not release reactor coolant to the containment atmosphere, detection methods should include monitoring of water radioactivity in the connected systems where the system V flows through the containment bomdary, and airborne radioactivity weiW$ $ A ', q where such systems are vented outside the containment boundary.
- Another important method of obtaining indications of tacontrolled
, or mdesirable intersystem flow would be the use of a water inventory balance, designed to provide appropriate information such as abnormal water levels in tanks and abnormal water flow rates. 1, .1. 4, r ~, Fotential dis:.harges from closed safety and relief valves are 9 . "pj usually piped to tanks or water pools and considered part of iden-n . c .! 3 *M .' . ., 1 tified laakage. Temperature sensor:. in the discharge path of safety and relief valves or- flow meters in the leak-off lines would provide .. : c. . . d an acceptable method of signaling small leakage from these valves.
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. < .hE , .,~. # . ~ ...-.,-.-...a-.~.___ . , , .. . _ - ._ :. . . . . . , [ - M f. W f ' j'. [ - . - ~.Sh'Thhg./h,hyM~ h..gfj9[;$aQ4 --~._.-_~u..u -y qft.$).yp f=yysy . '?.?' 9-(t3j - .,;.? :j - _ [gg, .. .y } L M* %l ~5- p ./jlu ~> ..? g.;; , i f f E ', L c.'; >* 'M j 1 Ed t h.- '.. ; 3. . p Q.,'T,d While the above-mentioned leakage detection systems reflect the re .r .- s ..; . present state of technology, it is recognized that other detection
- dd ; " ,;
! .$l ';f.I ! . . .d..pa! methods may be developed and used in order to obtain operating 1 f . _.. 9 y D.J. [, experience with them. Among such methods are sonic indicators and lL,1c m .4 a N C .i - I ! ',ik": moisture sensitive tapes ap 'fhe-parts.6 l'.s twe~.Nm zI s N pM d kpk ej .u. flied to RCPB luf component 4lubm ud /mko / - -deverlop=ane and usa _ of-. improved' methods- of leak. detection-are Ms'.3.< h,p % d.';w n h 6 balay . hen ~ kd"d? encouraged.} 4.'edd .k .W 4 f-F .. h 4 tl M aah
- p ,
It is not.re';uird that all of the above-mentioned leakage detection F; I methods or systems be employed in a specific nuclear power plant. , , However, since the methods differ in sensitivity and response time, ' ~ j - - prudent selection of detection methods should include sufficient [ }. systems to assure effective nonitoring during periods when some a h detection systems may be ineffective or inoperable. Some of these p- } systens should serve as early alarm systens signaling the operators r - [ , .x r that closer examination of other detection systems is necessary to h .5 determine the extent of any corrective action that may be required. ~ E 9 Detector Senshtivity g }}b sci:ja ::;_i. .ps.s.N0 .__ff. a;f f-leakage detecrion systemsp % nam lb a lb'h k '4*y *^ g, m I , detect significant RCP3 degradation as soon af ter occurrence as n I practical to minimize the potential for a gross boundary failure. w - s f . . , 1 It is possible that some cracks might develop and penetrate the [ RCPB wall, eshibit very slow growth and afford ample time for a a F . L E ., n > '- . w b g .. ,__ . .. - . . . , . . . - . - ,~ ., . ,p . : 3. . . ; . 7,7. y .. . . . . . c., . ..,-'.W",* ** . *, . - i ;;- .- .r. ' i;.i - .--'.7i.,,-
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'T. r s. *4,"- 6# 4* a$ 9, % IMAGE EVALUATION ///*gf 84*4, k//7p h~ ,yg f/ TEST TARGET (MT-3) yy ,, y , 9 /4*/[4'#, ' ,,,,,}$*4 . + % l.0 'd 2 m '( [j Nas i.i [i=EM 1.8 l l 1.25 i.4 i.6 1 4 150mm > 4 6" >
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/'4Mj>[d 4 %p +k+ h),;f;'p-j..]26@5NSQdt Mh.M$NNE5hhNhkih kh)$$kh,Nhik![![ffhh$$hk5h.k h. h h.. ~ l iWhwy . } -lanx1Gl. ,:1 .e , .g - 19J4 - . r% ys . ? :-n - . ,f . ?. :, (( , m;':K r e w.s .p ' 3.$$5 safe and orderly plant shutdown after a leak, is detected. On the .s .. : w x~w.. other hand, leakage such as that resulting from stress-assisted . f.%: .:::g;))i , d).M] -:s w , corrosion in stainless steel or from a flar at a high fatigue point ..w.s 5.$.; I in the RCPB would densnd rapid detection and probable plant shut- .f.j:M ,, N down. Therefore, an early warning signal is nacessary to' permit =$j,a.d ,k ~; ' -['.I.' proper evaluation of all unidentified leakage. u - ; g.* % ' . _ )
- k: -, Industry practice has shown that water flow rate changes of from 0.5 -
l _ c: to 1.0 gpm can readily be detected in containment sumps by monitoring . changes in sump water level, in flow race, or in the operating fre-v ~ g- quency of pumps. Sumps ' and tanks used to collect taidentified leak- , age and air cooler condensate should be instrumented to alarm for increases of from 0.5 to 1.0 gpm in the normal flow rates. This - ~ ^ * - sensitivity would provide an acceptable performance for detecting ~. increases in taidentified. liquid leakage by this method. } An increase in humidity of the containment atmosphere would indicate . release of water vapor to the containment. Dew point temperature
- 1. [- measurements E.an be used to monitor humidity levels of the contain-c.~
.$ ment atmosphere. A l' increase in dew point is well within the ~. k. . . .. p ;;. 4~.A. . . . G. . - sensitivity range capability of available instruments. Since the ,Ly . :m. /h,.,? humidity level is influenced by several factors, a quantitative m ; Q. 'f"'d' ~ evaluation of an indicated leakage rate may be questionable and J. y . should be compared to observed increases in liquid flow from sumps . .r. p .- ,k v.S v..~,; s f .* l b ' CE . i .W' wue 'Ok '? ',
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,2 M 3 . ,::c, z%.c .s. 5 . .2 cL .w'"x.~4 ' M. 5;2. .;.:v M l -Mic. $M \ ,%;i yy and condensate flow from air coolers. Humidity level monitoring is f< W"Q.h. K .gj -?d% considered most useful as an alarm or indirect indicating device to v y, mp p.,l . ~ . , alert tha operator to a potential problem. .S,p*1 r X.e nAt. s' i ~y~- Reactor coolant nornelly contains ' sources of radiation which, when .. . I, 4. j 7' Q.4 , released to the containment, can be detected by the monitoring sys- , :- 4 C However, reactor coolant radioactivity should be low during ' 2.] . tems.
- initial reactor startw and for a few weeks thereaf ter until activated
~ D . , Q y - corrosion products have been formed and fissic,n products may-be available from failed fuel elements; during this period, radioactivity monitoring instruments may be of limited value in providing an early J warning for very small leaks in the RCP3. Instrument sensitivities of 10 uC1/cc radioactivity for air particulate monitoring and of 10 uCi/cc radioactivity for radiogas monitoring are practical for these laakage detection systens. Radioactivity monitoring systems should be included for every plant (especially particulate activity e monitoring) because of their sensitivity and rapid response to leaks from the RCPB. u
- . h; .. . ,.; : '. Air temperature and pressure monitoring methods may also be used to t
l c';p>2i ] infer RCPB leakage to the containment. Containment temperature and . v. - r.: . 3 y pressure fluctuate slightly during plant operation, but a rise above
- GMfw lj
< ...s.c t h the normally indicate.d range of values may indicate RCPB leakage into The accuracy and relevance of temperature and pres- ,Wj*-li&,'fe*.y > the contain - t. ; n._ , 3. ~; 3 vaw. x 1 sure measurements is a ftsaction of containment free volume and ll '.9%,};d ?M9R !, T,ihi5$ ww. 3 h... a M A- . b o e 'scajB <m.,... . . _.c.@ l ',*.I'~f.ND[w- >:qgp Q.W, .u$ynD-$Wlm'WLp[*' . .w ,. : g W
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.- " y.. ? 7 Y .' EE'.~ ~ J.. ' ~ ~ ' ^ ~ ~ C5 - QQU-gji:: y.?.?:Gy(.~ ).mQ. gg- y;;;p f.l . - . - _ _ _ . ....s_ __ __. a ' ' *-~ a idh.is.N3N MOSE59]Ni1MpMM6$h$.m$NM~ -m ._('S._.;$..?iO((m.h.. .. ._ _ . .lk N Q. } _NSd,{d_ikN,m.N_$ m$.b.u ( Nm $e$;*g.-
- . n., .
+ m_ ::g<e,q e . .~de - d> . '; *.+ * "$'q .l ..m Q Q .=.n; g 3- 7 l 4 2Il@W'1 .?Wj p .o. . J:o.: s _7444ry, detector location. Alarm signals from these instruments can be . -4
- .w. ..w. c
.O35U. valuable in recognizing re.pid and sizable energy releases to the QS. ' n d.. M ,? containment. ~ 9 . ., n :l .._71. . .. . jy While the concern about instrument sensitivity applies to the lower range of service for which the instruments are selected, the upper instrument range limits should be established to prevent exceeding the saturation limits of instruments, thus making them useless as indicators of containment conditions. -- . - - - -. Detector Response Time - - - The need to evalusta the severity of an alarm or indication is' important to the operators, and the ability to conpare with indica-i tions from other systens is necessary. The system response time .. .~ . should therefore be included-in the ftmetional requirements for , ~. .%. 4, . f. v .Ci. leakage detection systems. Except for the limitations during the-init'ial few weeks of plant operation as discussed previously, all m . .. ~a ' ' detector systems should respond to a one gpa, or its equivalent, ~ leakage increase in one hour or less. Multiple instrument locations { ' .;. , j in monitored areas should be utilized if necessary to assure that # s the transport delay time of the leakage affluent from its source '.4_'4. ./. ' .! . =:M@:.3
- jRT.
. .z .. to the detector or instrument location will yield an acceptable
- 8. cw '-
~Q'U ~ . , w:..f;t,5,1 overall response time.- A useful technique in identifying the W 's,p : . .$ '- general location of a leakage area is the placing of several sen- ,:.:, V.:ai ~. .. a l@.g.gj sors within the containe: mat area and observing differences in .s.C,^V. .. ; 3l . L* v3 *nj '8 h'[ gi;iA9.0 .-y,1.t,y ....;,? l . S .. m**m... <if . . NI- j:?.flf . lf { , " ~ . .; . 9 _3 4_ -_9.~ y :e.y ;g m yfg.y y g g_ g wv: 4 - - %. . .u_ ._: _ . ~ . , . 5),$hE4.hh: NYIsYI.N$$.5kEhh:.._, $hN h_k.$NEhkkhh%Nf,Shhh['NIN!Mt$'kEk l g,>; 1 I %gm#::- . h%, ^ .'.Q)S)?. f'i - ...M' , _ '1 .g..:l.1 . : g . an
- 30 5 *Qq n :w.sa response from the sensors, and this technique should be used to
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ET.I Qt satisfy this requirement of General' Design Criterion 30. am.p_;e :5.) ' ., g.~ . 3 : ~ZD)) In analyzing the sensiti"ity of leak detection systems using airborne s., .. s . particulate or gaseous radioactivity, a realistic primary coolant radioactivity concentration assumption should be used. 1he expected values used in the platt environmental report would be acceptable. ) - --- Sianal Correlation and Calibration It is igortant to be able to associato a signal or 1r.dication of a change in the normal operating conditions with a quantitative leakage 1 .I flow race. Except for flow rate or level chstge measurements from 1 tanks, sumps or pumps, signals from other leakage detection systems ~ .a .3 _. do not provide information readily convertible to a common denomina- -_ : tor. Approximate relationships converting these signals to satics of ~~d water flow should be formulated to assist the operator in interpreting . 4 signals. Since operating conditions may influence some of the con- .' version procedures, the procedures should be revised during such ^ ~ periods. To assure the continued reliability of the leakage detec-cion systems, the equipment should cogly with paragraph 4.10 of .] 'I I 3 ,.c . . . '.,1 IEEE Std. 279-1971,1/ for tests and calibration.
- v. .
m . .+ ,, j 1 ' wp .,<::7 1j [g M al - Copies of IEEE Std.. 279-1971, "IZEE S tandard: Criteria for "?.??M Protection Systems for Nuclear Power Generating Stations," may ' M.. a[,Es. be obtained from the Institute of Electrical and Electronics _ N';NJ Engineers, thited Engineering Center, 345 East 47th Street, 27 .' ; i New York, N. T. 10017. . .s . ; s : i f..;.']:y, . w, *. ,a. n * ' ?j.d e **- y . p..' .*=.s.' - .,j ' , '+4 . n . . .~ .**, c:, - - 5&f. ~5 5 Y b f* * ? .u. . ;;,G h J . .-c . E * ' .f.%.. m'.m?:r .y ~~ ~ .l. %,; . p.' - ~;. , \ Y. ~, _ . m...v ..r,f', . g
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10 fy';)~5 .v?:m, l 6 X7t.yf, @Vp ;i xh, Seismic Qualification
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-$r$? rc s.:j Since nuclear power plants may be operating at the time an earthquake .m. <,C_.y.,39.W. ~ occurs and may continue to operate after earthquakes, it is prudent ,u , e ..;-s .'. : 'r to require the leakage detection systems to faction tzador the same l ,u.). conditions. If a seismic event comparable to a safe shutdown earth- , quaka (SSE) occurs, it would be igortant for the operator to assess e J 'I the condition within the containment quickly. 'Iha proper ftmetiening of at least one leakage detection system would assist in evaluating l l the seriousness of the condition within the containment in the event l l a leakage has developed ia 9- um N =4 rhnma particulate radio-l activity monitoring equipment has the desirable sensitivity to indi-cate RCP5 leakage, and it should be included for all plants. Components for the airbozue particulata radioactivity equipment should be qualified to ftstetion througit a SSE. ~. . C. Eag. ulatory Position h source of reactor coolant leakage should be identifiable to the extent practicai. Reactor coolant pressure botadary leakage detec-tion and collection systems should be selected and designed to ( include the following: ygg 1. Laakage to the primary reactor containannt from identified' . c:: : . .- i f q.1 sources should be collected or otherwise isolated so that: ; a.c:n ' .k.;2: ~r 1 1c;;;9 -i (a) the flair rates are monitored separately from tanidentified ~ .9 ~ ;q ],.p leakage, and ..g ** .r ,p.i*;
- .O.:n*.]
y: '~ , .. '- ( , ~ .s *r [. . . , 42, \ ,% , . 4 % . ,d', - . a. ; .;$y .,.; , ?*'-l.~ nY9W,lf.*0 ,f 9g;yq,..;.yy, [h $$f*5$$f5f5.?, y3g;rv. -(.y. ., f, ~ U- !3.g p: yp nm.f. i s v . ,, gi ,.mY.Q.' u;q ;.,a:. . '.e...?(i?.l.lGM, . .m. , y ' n*. ~ . j,h.(;s'k+Q.s& q. q Q} ':-j;i. , 77uj-l.L . f s-)?;;. _.3:. =. , j . hp.fhp[hhghdQ ! [h M h!E h M h F 'I Y ddihk0NNf h_hhkhy.hi f g .h-c' , - -t . .l . U$.,$. ^.M3?'N ..
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. :. ,.h.y;] ~~.v.... 1 . ,%: u.:.y-Q ?- ) M{$:W gMU Nh1 (b) the total flow rate can be established and monitored. i .9p-;W tr .w MIgd.; Leakage to the primary reactor contain= ant frca taidentified fft 2. , . .,m., :Q.~.y 3 . s* 7:)&Q - sources should be collected and the flow rate monitored with an ':'. iQX.d. ;.7.; , p.-j accuracy of one gallon per minute (gpm) or better. w;.. ; -- . ~ v' 3. At least three separata detection metho'ds should be employed and . . < 3-two of these methods should be 1) suse level and flow monitoring i k m. .N m-and 2) airborne particulate radioactivity monitoring. The third method may be selected from the following: .I (a) monitoring of condensate flow rate from air coolers, 3 (b) monitoring of airborne gaseous radioactivity. a *' Humidity, tenverature or pressure monitoring of the containment atmosphere should be considered as alarms or indirect indication , of leakage to the containment. .; 4. Provisions should be made to monitor systens connected to the .E RCPB for signs of fatarsystem leakage. Methods should include radioactivity monitoring and indicators to show abnormal vatar 4 levels or flow in the affected area. ,. - ,s , t I , j \ I' .. . 7f;:h.. . j 5. The sensitivity and response time of each leakage detection ;; .u.P / system in regulatory position 3. above employed for imidentified .iffid_.-7. y, ~-;y.: 8 93c.il leakage should be adequate to detect a leakage rate, or its l c*,.-. r . 3::. +. s equivalent, of one spa in less than one hour. l ~ 3-:;g: 0.f:.:; j -}1 \ I ;~ + _, ; . 4. :.-- : 3,', .s~W' wb .,W,.y . es:.. w : . '. ?:, *v1, . *,{' I['*. h ,. .,.' %) - .*;. h ,.'L '.i m.;p':n ,ya.g m & ,y: ~* $ ? t * ' . t . ; ,a ,- . ,- .. ;v v . .. u.. . % 7 ,? --:..>' t,- ; q 3- . : . y .91,,. 3 .. Q. . I
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- 6. 'Ihe leakage detection systems should be capable of performing r,q.gr.g
$m y36 their functions following seismic events that do not require ? .:. n, :-2 ]3n'91.r .t.t:.hE .; y}s plant shutdown. 'Iha airborna . particulate radioactivity moni- .w.- n L'y toring system should remain ftmetional when subjected to a SSE. . +
- c. ,,t ,
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- f ' ' ' . 7. Indicators ad alarms for each leakage detection system should
[ be provided in the main control, room. Proceduras for converting
- c. : various indications to a common leakage equivalent should be
. available to the operators. 'Ihe calibration of the indicators ... should account for needed independent variables. .
- 8. 'Ihe leakage detection systems should be equipped with provisions to readily permit testing for operability and calibration during plant operation.
- 9. The technical specifi~ cations should include the limiting
~ conditions for identified and unidentified leakage and address - the availability of various types of instruments to assure ade-quate coverage at all times. .I d n ..l7 . .* 3.y , . . v. : ' .ll 'g ' MI,y[. r ~, :=*i ' .c; : . ** (t * .W ri 0;p,:- .",
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