ML20042C681

Forwards Response to NRC Accident Monitoring Sys Cessar Questions.Info Transmitted for Review of CESSAR-F & Intended to Close Out Open Item 4 Identified in SER Section 1.7

ML20042C681
Person / Time
Site:	05000470
Issue date:	05/04/1982
From:	Scherer A ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
TASK-2.F.2, TASK-TM LD-82-051, LD-82-51, NUDOCS 8205100232
Download: ML20042C681 (30)

Text

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C4 Pamettyeesem Te' 20 u 68F o Cor'euston Engineer $rs 'ne Me= = M24 '

8000 Pvospect Hill Reed Winosor Connect' cut o60%

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u Docket No.: STN-50-410F May 4, 3' ?

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Mr. Darrell G. Eisenhut, Of rector - '. ? 4. >Hr I 01visten of Licensing $ 3 / C

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U. S. Reclear Regulatory Commission Meshington, O. C. 20555 \! N,#

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Subject:

CESSAR SER Open Item 4 E, ,

Reference:

Letter R. L. Tedesco to A. E. Scherer, dated January 19, 1982

Dear Mr. Eisenhut:

l y . A description of the Coeustion Engineering (C-E) Accident Monitoring System was added to Appeedix 8 of the CESSAR Final Safety Analysis Report (CESSAR-F) 2 in Amenenent Subsequently, as part of the NRC review of CESSAR-F, the Staff req,Nuuber 6.

uested additional information per the reference, i TransmittedherewithareC-Eresponsestoeachoftherequestedsixteen

. questions he enclosed information is transmitted for the Staff's review of CES F and is intended to close out open item 4 identified in Section 1.7 of the Safety Evaluation Report.

If I can be of asty additional assistance in this matter, please contact me or Mr. G. A. Davis of my staff at (203)688-1911 Extension 2803.

Very truly yours,

. . COM90ST!0M E r:!N ING, INC.

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.E herer Director Nuclear Licensing AES:ctk Enclosure sc: C. 1. Grimes 3

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Page '. c ' 29

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AESPWe$ES TO NRC AMS/CESSAR QUESTIONS O EST10s 1.

The stem w(11 edget the generic responses provided by the C-E C.<ners' Gr:;u:. in

f. CR=181 Qugstions 1 m 13 as CEsSAR's position. Describe the reistunsnu ,

, teeman us and CESEN I.

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t des the C-f %' Group documentation of the generic portion of f;.

) us @ tlN, efqENS-0737, Section !!.F.2 for the description of instrurnentat'on hr

-Capling.(!E). It provided a generic description of the ICC y

[ seng,er /presagstep requirements. System design detatis, including 4 . Si 1 Ing, and display were not addressed. The overall E , 9' . including the system approach to be utilized in

' , was. left to each utility. The CESSAR response l

i n S.'f!SS1 and teseguently' as CESSAR. Amendment Number 6, dated lQ is C-E's generic Accident g/ ,$ Appendix S, i

p. ) approach to address II.F.,2 requirements, as well as other g ,'. sing'and display. The information in CESSAR is e

GR-15 except that CESSAR also addresses the overail

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'figluded in CER-185. The AMS ivi CESSAR does not rgensent'any Individual utility response to the TMI requirements by the utility.

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MIELI Ca p. 4.1 and 4.3 of Ctb1N. statements are made referring to generic analyses. Please guete spectfic references.

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A. Generic Analyses teferred to en Page 4.1 of Ctb 185  !

The generte aselyses reforfed to en page 4.1 of CEb185 consist of an eyelection of Rfts for potential use as -an ICC instrument. Speci fically , thi s 2.4841psis evaluates t8e egege, escaracy and time response of RTDs and discusses

'their setential for use as an ICC instrument. N analysis is presented below.

9 i

e EVALUATION OF THE USE OF RfDs.FOR IWilf9EIRS TRADE 0uAft CORE C00LINr.

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,i.0 E M ftY A80 L W 11 El i j

'The teststence Temperature Setesters (AfD) in CI reactors are located in the

{ 'het leg and cold los pipe alls. - A mell protrudes 2-1/2 inches from the inner l

• mell ed serves as part of the primary pressure toenaary. The RTD is inserted

[icts the all frem seaside. ftport en the inner surface of the well and on the

'Rf8 help to assure good theruel cantact. Figure 1 shows a schematic of the RTO

'1w.etiens in a het leg.

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p Reec)SP eselant system temperature in both the hot legs and the cold legs are i

f,ettahegw'iththeRfD. Three ranges of temperature inoication existed in tne i

ertpkf M plants. The safety channel RTDs nave a smaller range of  !

k*11edt.sk{heignof' temperatore for a more accurate input to the Plant Protection

%[' ten Mand 1he control channel RTO provides The wide rangeinput for the Rea!

other centrol and senitoring systems. Rr0 prov.ces f indication for plant startup and shutdown.

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i tally, the het leg.RfD have a range from 5159 to 665 F. The cold leg 8

M Ipve ranges from q8Fto400'Fand$15Fto615?F.III As a

( lt of 'TWI-2 actions, additional wider range temperature indication nas been f

f , ,, to Sese plants and the temperature sensing equipment has been modi fied to E ide Subcooled Msrgin Monitor (Spel) input. The additional temperature  :

& destsetions range to a maximum of 705'F to 750 F. The accuracy of the 0

F.Mture indications are typically

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3.0 MlCIENT PERF0W4ANCE OF RTD

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[ The RfD have two functions during events that may progress to Inacequate Core g Coeltag-(ICC). They are used to detect the initial occurrence of saturation in l N ACS 45elant. ,Their range is adequate to do this for initiation from acwer p eperetted in which case the hot leg RTD will see saturation temperature 2

! first. $er initiation from the hot standby coolant temperature or from lower p hutdesats temperatures, the start-up range RTD located in the cold leg can be

[ esed to detect saturation because their range extends to lower temperature.

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The sesent function of the RfD during ICC events may involve tne tnitial p foefeation of superheet as the core uncovers. From the time of initial hsaturattenuntilthecoreuncovers,theRTDwillesperiencesaturaton

{ temperature - either of liquid, if the level is above tne '1ot leg, y of i Saturated steam, if the level'is below the hot leg. Fol1owing core ;nc:veg ,

f 1 the RfD may see the temperature of the superheated steam.

3 For the ive and ontrol tems, Syste9 30 plants uti' re net e: * .r. ,~

', reages o to 95'F and 80 to 6500F, an@-

m ses Above the range of the RTD. Furthermore, the temperature at niet 8

s'[.'N f starts for the'1oss of heat sink event is 668 F which is at the

.,5 b ifepper liiti,t, twen'the extended range to 750 F 8does act provide much

. M.caties of the uncevery interval.

? S.0 Y M RE3PONSE OF THE RTO i k) ' ihe r4sponse time of the RTD during normal operation is typically 5 to 10 y!( secottss. This response time as used here is the time interval for the signal g  :. '

te change by the factor (1 - 1/e), or 635, of the total change following a step if ' change

• in the fluid. tanperature. For. a linear differential system this 6

response time is the usual time constant. This response time includes effects

( -[ef the film coefficient between the RTD well and the coolant flowing at typical l ..so (velocities in encess of '44 ft/sec. It also includ2s the internal themal

' ,,'rist' stance of the mell, the RfD and the gap between the two which t s sometimes

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• fill'ed with a heat transfer enhancing material. During an accident, tne vel nity may be much louer if the punps are off. However, as long as there is f i l

j 11guld or two phase mixture over the RTD, the time response is not f significantly reked. l f

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1he time response of the RTD is examined for the interval when che core starts to' uncover and superheated steen, flows into the hot leg. There are two contributions to the delay - the cooling of the steam by the cooler upper

'p1'enum metal and the reduced steam film coefficient on the surface of the RTD

! uell. Figures 2 shows the steam temperature exiting the core for a .05 ft2 LOCA event, and also shows the temperature of the steam entering the hot leg.

Calculations are based on Appendix K. assumptions. There is a maximum lag in the het leg steam temperature of about: 200 sec. at the time of maximum temperature. At the time *he steam temperature exceeds the RTD range the celay is about 80 sec, mote that this lag is very dependent upon the particular scenario analyud, and especially upon the temperature which exists in the upper plenum just prior to core uncovery.

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) The second contributor to the RTD delay in sensing superheated steam is causec

by the decreased fluid film coefficient at the RTD well. It is estimated that tne steam flow in the hot leg causes an' increase in the sensor response time' from about 5 sec. up to about 30 sec.

i

6.0 CONCLUSION

i In conclusion, the RTD provides a good indication of tne approac'i to saturation and may yield some useful information during the initial portion of the uncovery interval of ICC events. During core uncovery there is a lag in the e r'esponse of the RTD which is not signficant when considering the 11mt ted range t' Cf the RTD and the comparatively long total duration of core v".covery.

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S. Generic Analyses Referred to on Page 4.3 of CEN-135 The generic analyses referred to on page 4.3 of CEN-185, #5 identifiec in the text, apply to CE top mounted thermocouples. In these cesigns the' (

thermocouples eet located inside the In-Core Instrumnt (ICI) support tube, 3: (

an elevation a few inches above the fuel alignment plate. The generic ana'yses l identified studied the response of a, representative top mounted CE core exit l

2 thermocouple to a 0.1 ft ses11 break LOCA (using Appendix K assumptions alth il all RCP's operating) and to a complete loss of feedwater event which is l analytically allowed to continue to core uncovery (see Figures 3 anc .1). The results of these analyses are presented in Figures 5 and 6.

, Core exit.thermocouples to be implemented in System 80 aca to me located below ;

the fuel alignment plate and are expected to have shorter response times than .

these indicated by Figures 5 and 6.  !

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i F QUESTION 3 4

What tests are planned for LOCA survivability?

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( MEEEE I

l CE does not plan to perform specific experiments for NTC survivaciltty af ter 3 i large break LOCA. As discussed in the response to question 4 of CEN-181, the MJTC support tube assembly is designed to survive a large break LOCA. The y design analysis is based on subsection NE and Appendix F of the ASNE So11er anc 4

Pressure vessel Code. As such, the stress limits for the core support

(,istructufts are adhered to 1'n the design analysis of the NTC support strecture. The deflection of the NJTC support structure i also limited to prevent damage to the NJTC instrumentation. As such, the stress anc

}. . deflectices are evaluated for a large break LOCA based on a blowdown ana'yst s Ek to assere stress and deflection limits are not exceeced, m,.

j In the WTC System 80 design, the probe and support tube will be furtner p protected from flew leads by being placed within an existing emoty CEA t1e tuce

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l RESPONSES TO NRC AMS/CESSAR QUESTIONS (continued:

i SESTIGI 4 l Ifnce the QSPDS and CFIts both utilize digital processing, what plans have tee, f unde to v611 data and test the reliability of C-E supplied software?

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" N,SPGtSE

, C-E will verify and validate the Accident Monitoring System (CFMS and QSPOS) ,

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~ softhsert through a systematic design and test process and a separate integrated temputer system Verification and Validation (VAV) audit. The AMS design and test

, precess consists of several stages, each of which is dccumented. These stages

" faclude:

Functional destp 1.

2. Hardware design (in parallel with software tasks)

3. Software design , l

4. Software taplementation l

5. Software implementation testing

6. System velfdstion. testing "As independent V8V team will review and audit each design stage. The V&V team

,will veri that the product at each design stage is documented properly and  ;

fulfills 1 the requirements imposed by the previous stage. The V&V team wa.1  !

vel 1deto thet tho' ted computer systan complies w1th the functional, perfomence, and inte de requirements. l

, Although the NES is not a protection system, the above approach adopted is an I

, eutgrowth of C-E's experiences with Class 1E software development (as a re: ult of I iC3 protection grade Corg Pr4tection Calculators reviewed and licensed by the NRC br Arkansas Nuclear One - Unit 2)and recent industry standards and practice..

In particular system ' design and V4V are consistent with draft standard SSR/  !

f AIIS 4.3.2/MEE . 'Spp11 cat < on Criteria for Prograsmable Digital Computer In addition. I t fysteme in Safety Systems of leuclear Power Generating Stations.

can independent outside censultant developed a V&V audit plan as input to the C-E var plans.

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i f ftt3PONSES TO amt AMS/CESSAR QuF.STIONS (continued) k r..

k. - WESTIGI 5.

(f Computer systems can be less relistle in industrial environments because of EM.

E 'telet, mesures will be taken to protect the RVLMS against EMI?

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k ' I,- iAestent filalitering Systes computers, in particular the Qualified Safety Mapley Mtes (05Pos) whi.n perforses the reactor vesset level

%'" stet functienti ape, required to be located eaternal to harsh environments.

by ' la ler, coaguter is se be located fn a control room type of b* en . W eatensive emperience with computer EMI site surveys Gesnee, and Beguns Ferry) and susceptibility testing as a l'Me.g.p' ir40ml .i Fede Core Protection Calculator system design efforts. As

>, e twelt of 4$erienges and 'use of similar desf gn technicues, C-E does not 6,,. espect neise . ..

The 05P05 spectfica11y includes:

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[j 4 1. ,Isoletteil' end Pfitering of therwocouple inputs,

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Filtering of high leel inputs, 0Ptical, isolation of digital inputs /gutputs.

S 4. 'Use of fiber optic data link outputs, and I!c 5. Use of shielded input cables.

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k RESM3tSES TO NRC AMS/CESSAR QUESTIONS (continued) 6

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i ) Util any signal isolation or protection circuits be used for the inputs to the

' i' @ system?

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': ? The 6 is i to meet Class 1E isolation requirements. Any non IE signal

y E input to the is isolated before it enten the QSPOS processor. In particular,

, -[,h; the W provides fbr digital signals to be optically isolated, thermocouples

, with th " flying capecitor" technique, and the high level analog signals

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asasures the collapsed water level (water inventory) in the

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. the Niel Alignment Plate (FAP). The volume above the FAP v-f vesse, . .

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'l ' $ %s$- golfelcanbepicturedasbeingtwoseparateregions les .v., the FAP and Upper Guide Structure Support Plate hl) a, t v:....4

. pled. The second regten, between the UGssP and th.e top 'of

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' p ,.. Sejsessel  ; Xthe ag head. During normal operation, the majority of the

. fkes' fr'out the'ckgees threhgh holes in the FAp into the upper plenum and out the i

[ f5Et.148. AM'en of the.fleu goes up tubes which extend Mross the upper plenum

~j.asf.fots' the uphr' head. Ihles in the UES$p allcw water in the upper head to flow i 'k,date theh.pieneniisd. set the het legs. f f .q,t < < . ,

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prete easedly for;.lystes 80 plants is designed to measure the collapsed i..spel?te/tiiis~epper med independently from the collapsed water level in the f

' I 10 pidseen. 'M.r 'fslacch_ isted by the use of a " split" probe assembly m

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! $ .. y,. )[ E!Isetiesellp { the probe is divijed into an upper separator tube hqat:i%gles) Idd..a lower seperator tube (in the uppe plenum region). l

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~,yM-o%K9e gDehe located at'the UG55P elevatij

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.jd $ i Jtiser tgees plically, Neles at the top and bottom of each separator tune M[{ u . n . . n.

8it cellepeed unter level in each region to be formed inside the separator I

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? . Sic p. 5fft sensors erg leested Asia 11y in the probe assantly so that the collapsed

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-tue prete'e,s'seelies are located so that they are equally spaced within l % ',y , each reglen. Fear sepeers are located in the upper head and four sensors are in p,7 ,,the opper plenus. One senser is placed at the top of each region as hign as

? possible. It provides the first indication of voiding in each region, y .. +

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L h sensor is placed at the bottom of each region as low as possibic. This g sensor indicates when the region becomes empty of water. In particular, tne i F -

le, sest sensor in the upper plenum indicates that little water inventory is e

, ,. IgPt above the feel alignment plate, and, thus, gives an advanced warning c,f h . ' M ing core uncovery.

V; -3 y _ The f.testning sensors are placed so that all sensors in a region are equelly r ,,, O W. The sensers .n the upper plenum are closer togetner since the uppe-1 Wenusisshorterthantheupperhead. A closer spacing in the uceer plenum v.

desirable to give the operator mo're infonnation when the collapsed =ater level

'ftlls closer to the core.

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RESPGt3E5 TO MRC AMS/CESSAR QUESTIONS (continued) i r

I' f.,M!h'n. -(

ypher af core exit themocouples to be useo for detemining the tative core exit temperature been determined yet? If so, how .mny will

. .7 g . '. r, v*.

, n . .f . t 7.' " all salid core exit thermocouples (CETs) input to each Qualified Safety

'ti 91 splay System (MS) shannel will be used to detemine the 7 tive com estt thennecouple (MT) tagerature. The C-E System 80 t

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~81 . 4W08 Channel A hes 31 CETs and Channel 8 has 30 inputs.

en f5'sesh thet at least 6 CETs are distributed as onifomly 0@ in seghfef the core goedrents per C3POS charnel. T-E is in the

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evolueths the sufnfam mueer of valid CITs necessary for ICC

'"d .' The evolgstfee .fs intended 90'detemine the reduced conclement of will se$dtely 4tect initial sere uncouery and trend the ensuing The eveleftiens escount !c6re nonent fomities, including in-core of the 'redfel degey power dis 1on and'esMpore effects of te runktsk is the het legs and assunifom inlet temperatures. Based on F lisettoes. ly estiettige that adeguate ICC detection will be k.

$th tue we 1_ 'per quadrant Therefore, the full core copolament available in the 4 System W~ design are considered to be more than

., '4r use la Edetection, sed provide an additional degree of w tonal flamibilfty. Question 14 diteusses how the valid CETS are selected.

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RESPGtSES TO NRC AMS/CESSAR QUESTIGIS (continued)

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am te be used fbr the setpoints for the difference between the of the heated and unheeted junctions in the HJTC and.the unneated SSEpeft9Bre87 t <. . ,

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$ welue. fbr the d1Merential tempesture (AT) and the unheated junction

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(7g) Jewel setpefnts will be ~ based on test results (including Phase i;

3 ) and 'a setpetet' celculation. .[The AT setpoint is expected to be within 4 . .h sheeted junction (T );setpoint will be between the saturation

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at:M(EMPF tu M 'NE'F).s#ptp dive lift preesgm and a value based on The R:setpoint is selected to ensure covered tiene can' he distinguistesi from each other unambiguously.

tetpeint is used te ' ensure a continued indication of sensor uncovery in

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JWture sevirgneants when the appliad heated junction heater power is gygn ,M to prweet overteeting the NJTC.. .

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AtSPONSES 70 NRC AMS/CESSAR QUESTIONS (continued)

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!: tes compem inputs from the A and 8 crains of the QSPOS for I , yfo se, and an inconsistency is detected, describe the systet

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the tse QSPOS channels ,are displayed on the CFMS in a sonner the operator to easily perform: 1) cross channel checks of the and 2) Nrther validation of the readings using other

-outputsM1y, As automatic A to 8 channel comparisons are 5 meens.

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I RESPONSES TO MRC AMS/CESSAR QUESTIONS (continued) l

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l ~ that sensor failures occur in such a way that there are incomoietz sets  !

in teth Train A and Train 8 of the QSPOS; #or instance, for :ne l l -

'te the M. but if the signals from the surviving sensors could :e l

' 4 couplete set could be made effective. Does the CFN System na,e tne I

$111ty costine signals from different channels of ene OSP05 to prov4 :e a  ;

essSiets $1rerview is spite of individual sensor failures? l y: .2 , l l

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!4 ' , , poses the ability of the CFMS to provide a complete overview .<1:* I I 4 ,6 1Rput sensor 411 pres. The CPtS provides the primary display of CC l l

(R calcelated values. 8ecause it utilizes both QSPOS A and B Channel i P ft has the ability to provide irdependent display of all ICC carameten k

g s, including failed sensor indication. The CFN has the ata ! : :,

i ki both Land 3 Channel inputs for calculated parameters, and does sc

• f irgin calculations (this is, in effect, a third channel sa:arat on l

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t l-u 5 Describe hans me setpoint for the upper head or RC3 temperature saturatior J , '* sorgte 4111 he selected.

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(,g 1he bl$ test of' me taperatures from the top three unheated thernoccupies of the

(( , NJTC p fres EfD's le me het and cold legs will be used along with pressure to

, detsiglos the, degrees tasperature margin to saturation. The objective in selecting

{$, the' set,peist is to deterulee a minimum required margin whien. allows norrai power s

[C) operation without as alans. This value is comLined with the instrument d uncertainties to determine the Q$PDS saturation margin alarm setpoints.  ;

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t E 2.2.3: Gescribe how the representative core exit temperatare is to be t h_ es c .. god when the method has been selected. When will the method be selected:

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' MFuel E5 cosiditieges (saturation margin alam not active), non-valid core W (CETs)~will to detected with out-of-scale checks, tolerance gi

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Statistico1 analysts. CETs outside of a statistical band based on

.and,a ff talerance band will he flagged as failed sensors.

se t-$$perature will be selected fmn the upper end of W *df tutifte'.ef the remeising va!id CETs. While'a saturation F '

98 fadicatNug abnornel RCS conditions, the same method will

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tive core exit tsuperature from among the valid L 5ft, not.~ductag

'nomal operation. The out-of-scale failure checks

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4. 15. Table 3-3 Itas 1: The phrase "best available equipment" in ene la3 :

. . peregraph of page 1 of Table 3-3 is not sufficiently specific. Proviac sample purchase specifiestions for the HJTC sensors and CE~ sensors (e.g., ISA theressouple toleranca, insulation resistance tolerance,

- er appropriate RfD temperature standards). l, i' R.15. Rigid engineering / procurement specifications are invoked upon equio-  !

ment suppliers which dileneste requirements for manufacturing, perkmance, inspection and testing. Standards invoked irclude the following

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, {, ASTM E - 1(2 - htheds for Controlling Quality of Radiographic i MD l i

NIL-STD-271 - Rendestructive Testing Requirements, (wnere Q ,

applicable).

dEc NIL-STD-105 - Sampling Procedures and Tables for Inspection by Attr'butes.

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ANSI-STS-M45.2.2, " Packaging, Shipping, Raceiving, Storage e and Handling of Items for Nuclear Power Plants."

5 ASE Seiler and Pressure Vessel Code sections III and IX.

[ 25 Monograph 125 - Themocouple Reference Tables based on the IPf5-64. l i

, 15A Rp! 1 Thermoceuples and Thermocouple extension wires. l

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ASTM E-220-F2 - Standard Methods for Calibration of Thennoccuples

, ty Comparison Tecnniques.

(*, Thorneceuple televennes for the WTC's and CET's are specified in the pre l

. curtest specificettens as Wall.

For the HJTC's the TC calibration shal! !

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demandtrate coefseesses to standards within + 4'F from 700 F to 530 F an:

. withis + 3/41 of the actus1 tagerature from7300F to 7500F,

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, thee la eveh 20 MTC sensors is calibrated to la00'F. The procurement

". q' aggciffsetiest require that the NJTC insulation resistance be at least

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les seus at 19ger eng at least 1011:ohns at room temperature. The ex-vessel pertion et De NJTC probe desemblies i.e., the portion of the pNbe.'entending fNe the vessel flange surface to the electrical

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ceanectors and including connectors, will be qualified to seismic i

' ~ and cov1Nnmental standards set forth in IEEE standards 323-1974  :

ed 304-75.

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l afspoe5ES TO MC AM5/CESSAA QUESTIONS (continued) l t

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t Ghe b3. Itas 11: please previe description of servicing, tasting, and geTitretion p m grens as soon as availatie.

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hrvletag. testing. and calibration pescedures alace at monitoring the systee 111ty will to addressed en a plant specific tesis, besee on the specific

? erfengemente and hertnere tasm11atten, saintenance precedurws, and plant Infurteel agaciffections. The reopense provided in CEN-181-p to Question 12

,$ 5strides addittenal inforgetten relative to generic periodic testing. Included -

t -We altamations of the e111% of me aperater to test the system (sensor through

' C.ephy)et11etheplantisoperating. In additten, beyond these recut re-ents-act cepet111 ties. Ce 2111ty of me computer to perform automatic on line testing tes diesassed.

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