ML20154N684

Forwards Checklist for plant-specific Review of Inadequate Core Cooling Instrumentation Sys,Per Generic Ltr 82-28 & NUREG-0737,Item II.F.2.Instrumentation Supplied by C-E Includes Subcooling Margin & core-exit Temp Monitors

ML20154N684
Person / Time
Site:	Farley
Issue date:	09/20/1988
From:	Hairston W ALABAMA POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM GL-82-28, TAC-45132, TAC-45133, NUDOCS 8809290375
Download: ML20154N684 (78)

Text

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A!abama Pc4ef Cottpany 600 N xtn 18th Street Post 0",ce Box 2641 8.rm ngham. A!stama 352914400 Tetephone 205 25o4837 W. G. Hairston, m Senior Vice Pres'dert Alabamalbwer cesen wnewrcs,wm September 20, 1988 Docket Nos. 50-348 50-364 U. S. Nuclear Regulatory Commission ATTib Document Control Desk Vashington, DC 20555 Gentlemen:

Joseph M. Farley Nuclear Plant - Units 1 and 2 Inadequate Core Cooling Instrumentation System Generic Letter 82-28 and NUREG-0737. Item II.F.2 TAC Nos. 45132 and 45133 By letter dated December 10, 1982 the NRC issued Generic Letter 82-28 "Inadequate Core Cooling Instrumentation System". In this letter the NRC requested that Alabama Power Company take the necessary actions to complete the installation of an Inadequate Core Cooling (ICC) instrumentation system in accordance with Item II.F.2 of NUREG-0737. Alabama Power Company has submitted several responses to NUREG-0737 and Regulatory Guide 1.97 in the past that addrens core-exit temperature, subcooling margin, and reactor vessel vater level. In letter dated April 2, 1984 the NRC Staff stated that the core-exit temperature system vas evaluated and accepted based on the licensee's commitment to upgrade to meet environmental qualification requirements. The subcooling margin monitor design was approved in Supplement 5 of the Farley Safety Evaluation Report. This letter provides a description of the latest modifications to the ICC instrumentation and supersedes previous submittals to the NRC related to system description.

Alabama Power Company hereby requests plant-specific approval of the reactor coolant inventory tracking system (RCITS) installed at Farley Nuclear Plant.

The ICC instrumentation supplied by Combustion Engineering includes a RCITS, a subcooling margin monitor, and core-exit temperature monitors. Alabama Pover Company completed the installation, functional testing, and calibration of the RCITS during the Unit 1 seventh and Unit 2 fourth refueling outages. Final installation of the upgraded subcooling margin monitor and core-exit temperature monitor vas completed during the Unit 2 fifth and Unit 1 eighth refueling outages. The subcooling monitor modification vas not requited as a result of the R.G. 1.97 revievi however, this function is being included in the ICC cabinet for convenience, pDR809290375 880920 p ADOCK 05000348 PNV

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U. S. Nuclear Regulatory Commission September 20, 1988 i

Page 2 l

l Alabama Power Company has completed all of the equipment upgrades needed f to satisfy the requirements of Generic Letter 82-28 and NUREG-0737 Item l

i II.P.2. Both the Units 1 and 2 RCITS are in use and available to the  ;

l operators for familiarization and operator trainings however, the RCITS i

, vill not be declared operable until plant-specific approval is obtained [

from the NRC. Revisions to the plant emergency operating procedures to i incorporate the RCITS instrumentation vill be prepared, and a task analysis vill be performed using the plant simulator to validate these

proi.edures. These revised procedures vill be implemented upon receipt

of plant-specific design and installation approval from the NRC. [

l Existing plant emergency operating procedures include the use of i i core-exit temperature and the subcooling margin monitor. This sequence [

i of isolementation is consistent with the milestones stated in NRC letter i j dated' April 2, 1984. [

9 The technical guidelines for incorporating the RCITS into the plant-specific f emergency operating procedures is provided by the Vestinghouse Ovner's l Group generic emergency operating guidelines as modified by Vestinghouse l t to reflect the Combustion Engineering heated junction thermocouple  !

I system. These technical guidelines are provided as Enclosure 2 of this j i letter. Alabama Pover Company requests NRC approval of these guidelines  ;

for developing plant-specific emergency operating procedures.  ;

j A request for a change to the technical specification to incorporate the t

RCITS vill be made by a separate letter in accordance with a schedule  ;

j agreed to by the NRC project manager. Alabama Pover Company vill  !

request in 'his submittal that implementation of the technica) l j specification be deferred until

1) resolution of a varranty claim with Combustion Engineering regarding three installed probes that have 7

i inoperable sensors is completed (currently scheduled for the Unit 1 9th ,

and Unit 2 6th refueling outages): 2) procedure guidance provided as  ;

Enclosure 2 to this letter is approved by the NRC 3) plant-specific t

. approval of the RCITS is received from the NRC. Alabama Power Company T i vill use the RCITS with prudence in relation to operator action until f plant-specific approval has been obtained from the NRC. The three  !

. installed probes with inoperable sensors are the only known deviations  !

from design expectations. The information provided herein is based on the current designs however, the ICC instrumentation may be modified in the future.  ;

f I Provided as Attachment 1 to this letter is Alabama Power Company's response

to the Appendix to Generic Letter 82-28. Attachment 2 responds to Enclosure I j 2 of the NRC letter dated April 2, 1984 vhich outlines the milestones (

j for implementation of the RCITS.  ;

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U. S. Nuclear Regulatory Commission September 20. 1938 Page 3 If there are any questions, please advise.

Respectfully submitted, ALABAMA POVER COMPANY 0 "

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V. G. Hairston, III VGH.III/BHVidst-TS7 Attachments cc: Mr. L. B. Long Dr. J. N. Grace Hr. E. A. Reeves Mr. G. F. Maxvell 4

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ATTACHMENT 1 Cheellist for 31aat.5pecific,Restav et, Tsadeguate Core Coelt.ng (ICC) Eastnmaataties syst,as ,

50-348 l yer J. M. Farley Nuclear Plant - Units 1 & 2 Decket Be. 50-364 l eyerate'd by: [AYabamspowerCompany l

4 l

I . The fe11eving itema for review are taken frem WREM737, pp T!.F.1-

3. and d. Responses eheuld be made to full reguirements ta tr3EH737, c:;t a%reviated for=.s telev. Applicants should provide referassa to i Cither the applicaat's subsittal er the generic descripties under the 4

C01mm labled "Referente." These items are reguired to le reviewed sa a plant specific basis by N313-0737 for all plants. Differences from the t

generic descriptions providad by Vestinghouse, the Westizabeusa Ovsar's Creup. Combusties Engineering, or Ce=busties Engf.neering Owner's troup

. must la indicated by "yes er me" da the celu=n labled deviattens av.4 f must.% justified. Under the celu=n labeled schedule, either indisate - f

, that your docunectatien of the ites is eenplate er provide a proposed sahadule for your sub=ittal. -

• l Referente Deviations *' gehedule l 4 1. Descripties of the protesed final  !

l systaa ine.ludfast i a. a fimal design descripties of  !

, additional Lastrummataties as.d i

) displays: _ Enclosure 1 No Cteelete i n. detailed descripties of esistlag i

! 1astrumentativa systana. _ Enclosure 1 No Complet e i s. descr(pties of eenpleted er ,  !

! planned modifications. Enclosure 1 No Ctrolete j J

3,. A design analysis and evaluaties of ' CEN-185 l;. laventory tread tastrussstaties, and Supplements  !

test data to support design la 1. 2. and 3*

J stas 1. No C rolete l 7

i 3. Descripties of tests planned and l l results of tests te=p1sted for CEN-185.

eva.lnaties, qvalificaties, and Supplements .  ;

i 1. 2. and 3

• No Complete i salibrativa of additienti tastre- i l

4 maataties. ,

1 J

i *CEN-185 with Supplements 1, 2, and 3 were transmitted to the NRC by i

! Combustion Engineering owner's group letters dated September 15, 1981; j November 25, 1981; and September 30, 1982. -

3

4. Frrrtie o taite er deserf; ties coverbs the.avalestie:r of evn-for:Ance with WIM-C737: II.F.2 Attach =est 1, and A;;endt.: 3 (to e be revieved es a plast s;et.ific CEN-ISS b aa f.a)

• Rection 8) No Complete

3. Describe tes; uter, softvare and di s;1 a y fe,= e tin.a sa s o cia t a.! wit.h 2CC n=1torhs la the pla=t. Enclosure 1 No Cc 01ete

4. Fredde a pts;osed sc.hedde for

. in s talla tice, t e s tf= g an d sali- Safety Para eter See Alabara Power 1

bratic a:d hyle =estat,te: of a=7 Display System Cc pany letter to p r e;c e e d nev 1:s tn:=a.:t.a tion er (SPDS) No NSC di ted Dece-ber inforu tie displays.  ! .1C

7. teserite raideltzes for use of reactor coolast investory trackt:g Enclosure 2 &

systes, a t a alyses used to develey Attactrent 2 proepfures. Ite- 2 No Co plete

8. C7 rator instructi ns is e=argesey e;erating ;rocetures for ICC and hev these precedures vf.11 he zodt!!ad when f t:a1 s.::.iterbs systen is i=;1e=estaf. See Cover Letter

9. prwitc a s ), fde fs; aflitter.a1 svh:.ittala requitad** 'e M c a W eification U" * )

l II.F.2 Attad rat 1 (for Ce'ra Ertt Ther=: couples) i 7: response to ite= 4 1 t h e al ev e cl e dli s t , ti e f =11 r.'. s u t e ri als should be heluded to at:v that the ;re;: sed syste: teats the dents: a4 gualificatin criteria for the core c:r.it t.hans:ev;1e system.

1. Previte diagrr.: of core erit theruce ;1e locatte:s er refers ce the gn=stiu desert; ties i.f a;;te;riate. (See Enclosure 3) 4

2. Fr wide a descri; tic of the tr bary e; erat.or dis;1ays i=cluths: (See Enc 1csure 3

(

a. A diag a= et the display ;asel layest for tt. core m; a:d descrip-tic ef h:v it is i=;1e=e:ted, e.g., harivara er c2 diay147 l n. Frevite the ra:ge of the reade:ts.

e. 34 s crite th e alar = sys tas.

d. Describe hev the ICC fastrw.a:tatics res!:uts are arra:get with r es p e ct t o a.a ch o ther.

3. Describa the i=;1ezentattes of the is

kup dis;1sy(s) (f.neluths the suits:1hg urgt: 4,r.: for

! tors), h:v theathe==:ru;1es bsv they are shed eteratiltt'y, 4 tia ra ge ofare thesaletted, display. pee Enclosure 3)

4. Destribe the use of the yrbary a:4 is:kv; displays. W at tra*-' g vi.h1 the operators 1.sve f.: ushg the ::re att ther:stn:;1 1:stru-1: s t t a t ic.! Irv vill the eierater k=:v st.e: to use the care a=1r.

l th e r=:c og;1e s a:t st e: ::t to w e thest F.aferes:s appropriate a=arge=,7 c7 rati:3 raf f elizes v'.are a;;1icatie. (See Enclosure 3) i

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3. Cesfire avspleties of sentrol reen desigs, task analysis apptitable to ICC instrusestaties. Cesfirm that the aere amit tharsecouples meet the ariteria of Wus-9737, Attachseat.1.and Appandia 3 er identif and

4. justify deMatteam.

Describe what (gee parts eNe systema are Egogeg'p.

5 pwar everad free the 1E andeeurses Alabama Power seed,.and hw isolaties frem mes-12 oguipsaat is previded. Describe the ywar evpply for the primary display. Clearly delianate da two eategories which hardware is daalsdad up to the imelatisa devise and which ta ast.(See Enclosures 3 ,

7. Cesfirm the envireanestal qualificaties of the sore azit,thersecewpla tastrweatattom up to the isolaties devisa. (See Cnclosure 3)

APyendia 3 (e( R:2 >4737. 12.7.2)

Cesfire ewplicitly the easformaase to the Appendix 3 spesa listed belev for -

the ICC instrumentattes, i.e., the SF.M. the reanter evolaat laventory track.ing system, the sore exit therseceuples and the display systems.

Refereste Devistie E

1. Eaviressestal qualificatisa See Enclosure 5 None

3. Single failure analysis See Enclosure 5 None

3. , Class 1E Fwer segres See Enclosure 5 None

4. Ava11abi.11ty prior to an accident - ca e Enclosure 5 None*

3. (tuality Assurases See Enclosure 5 None 4.' Cesttaveus indications See Enclosure 5 None

,7. Ras *erding of instrument eutysts See Enclosure 5 None S. Ideatificaties of fastnaments See Enclosure 5 None

p. Isolatten See Enclosure 5 None ll i

8

1

• • Tor the users of either Cathusties Engineering daated function thermocouple (RJtc) Systga et Vescinghouse Differtatial Pressure (dy) systes a detailed ,

reopense to tha plast specific stama stated belov should be provided. * '

Referosea Deviations A. Westinghouse dp system -

1. Describe the affect of tastranaat uncertalatias en the maarurssant of level. N/A

2. Are the differential pressure transducers located outside centstamaat? N/A

3. Are hydraulie iselsters and sensors taeluded la the impulse-limest tuA

3. CE EJTC system

1. Discuss the spacfag of the ser. sors frez the core align-sent plate to the top of the reactor vessel head. Rev vould the decressa in rest,1uttes due to the loss of a single sensor affect the ability of the rystem to detect'an approach to ICCt See Enclosure 6 None i

l

ATTACHMENT 2 Provided belov are Alabama Power Company's responses to the milestones for implementation of ICC instrumentation as outlined in Enclosure 2 of NRC letter dated April 2, 1984:

Item 1 Submit final design description (by licensee) (complete the documentation requirements of NUREG-0737. Item II.F.2, including all plant-specific information items identified in applicable NRC evaluation reports for generic approved systems).

Response

A complete description of the final design of the ICC instrumentation system, along with the complete documentation of NUREG-0737. Item II.F.2, is being provided in Enclosure 1 of this letter.

Iten 2 Approval of emergency operating procedure (E0P) technical guidelines (by NRC). -

Response

The Farley-specific emerFency operating procedures for the RCITS vill be based upon the generic emergency operating guidelines that vere submitted to

! the NRC by the Vestinghouse Ovner's Group (V0G) and subsequently approved for implementation. However, the V0G generic guidelines reflect the Vestinghouse differential pressure level indication system. Alabama Pover Company requested Vestinghouse to prepare emergency operating procedere guidelines for the Combustion Engineering heated junction thermocouple

system that is installed at Farley. These technical guidelines were prepared and reviewed by the ssme persons within Vestinghouse that participated in the preparation of the Vestinghouse Ovner's Group generic guidelines. Alabama Power Company requests approval from the NRC to use the technical guidelines included as Enclosure 2 for developing plant-specific emergency operating procedures that reflect the heated junction thermocouple systea. Tarley-specific emergency operating procedures for the RCITS vill be prepared, validated on the plant simulator, and implemented upon receipt of plant-specific design and installation approval from the NRC.

1 ,

i Item 3 ,

Inventory Tracking Systems (ITS) installation complete (by licensee).

Response

The RCITS vas installed in Farley Unit 1 during the seventh refueling outage  !

and in Unit 2 during the fourth refueling outage.

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l Attcch::nt 2 Page 2 l Item 4 i l ITS functional testing and calibratim complete (by licensee).

Response

The RCITS vas functionally tested and calibrat,3J at the factory before shipmint to the site and again af ter installaU - for both units.

Ites 5 Prepare revisions to plant operating procedures and emergency procedures based on approved E0P guidelines (by licensee).

Response  !

l The plant emergency operating procedures vill be revised to incorporate the l RCITS based upon the Vestinghouse technical guidelines (Enclosure 2), if approved by the t E . (0ee response to Item 2.)

Item 6  !

i Implementation letter report 'o imC (by licensee).

Response

The cover letter addresses the issues specified in the NRC April 2. If-A letter for Implementation Letter Report Content. (See Item 2 above for E0P technical guidelines.) Test esults are available on site for imC review.

Ree 7 Perform procedure valk-through to complete task analysis portion of ICC system design (by licensee).

Response

A task analysis vill be performed on the RCITS utilizing the revised emergency operating procedures. These procedures vill be validated on the plant simulator which reflects the plant control room configuration, l

T Attechtsnt 2 Page 3 Ites 8

~t.rn on system for operator training and familiarlzation.

Rerponse The RCITS has been installed in the control room for the past cycle for both units. The system vill be used with prudence by the operators until plant-specific design and installation approval is obtained from the NRC.

Ites 9 ,

Approval of plant-specific installation (by NRC).

Response

Alabama Pover Company requests plant-specific approval of the RCITS installed at Farley Nuclear Plant.

Iles 10 Implement modified operating procedures and emergency procedures (by licensee).

Response

The revised plant-specf.fic emergency operating procedures vill be implemented upon receipt of plant-specific design and installation approval ftom the NRC. Alabama Pover Company requests approval of the Vestirighouse technical guidelines for developing emergency operating procedures that reflect the heated junction thermocouple system (Enclosure 2).

1

v/

ENCLOSURE 1 Inadequate Core Cooling System Description I. Introduction The Inadequate Core Cooling (ICC) Honitoring System is a safet/ grade processing and display system which meets the NRC requirements to provide i the capability to monitor the approach to, existence of, and recovery from i potential reactor core inadequate cooling situations. The requirements addressed by the ICC Honitoring System are defined in Paragraph II.F.2 of I

NUREG 0737 "Clarification of THI Action Plan" and Generic Letter 82-28.'

Inadequate core cooling monitoring requirements are met by measuring and displaying margin to saturation, reactor vessel vater level above the core, ,

and core exit temperatures.

The objectives of the ICC Honitoring System include:

Inadequate reactor core cooling instrumentation signal processing and i cisplav.

Class lE control room display of inadequate reactor core cooling

instrument signals.

Isolation and data linking of IE signals to the Safety Parameter Display }

t System.

1 Upgrading the existing core exit thermocouple system to meet Class lE requirements. [

i Instrumentation to provide the capability for direct monitoring of the .

j reactor coolant inventory inside the reactor vessel.

I  ;

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Encicsura 1-Inadequate Core Cooling System Description Page 2 II. Description of RCITS A. Design Features of RCITS l

The Heated Junction Thermocouple System (HJTCS) is designed as a simple, reliable, accident monitoring instrumentation system with the intent of providing information to the plant operator concerning reactor coolant inventory in the reactor vessel. Major design features are as follows:

' Designed to Safety Grade Class lE requirements.

Installed in the reactor vessel to provide the capability of measuring coolant inventory in the reactor vessel.

! Designed to minimize handling during refueling operations.

l Designed with no noving parts.

Designed with no in-containtent electronic components.

Designed to allov testing of system availability during plant operation. ,

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~ Enclosure 1 Inadequate Core Cooling System Description Page 3

B. System Configuration The overall system functional configuration is shown in Figure 1. As indicated in the figure, the system consists of two (2) independent safety channels. Each channel consists of one probe assembly, cabling, signal process!ng equipment, and an operator interface (display). Probe

, assemblies are located in the upper guide structure of the reactor i vessel. Signal processing equipment and operator interfaces are located.

i outside of containment. The cabling connects the HJTC probes to the signal processing equipment.

a. Probe Assemblies The HJTCS measures reactor coolant liquid inventory with discrete HJTC sensors located at different levels within a separator tube runnirg from the top of the core to the reactor vessel head. The basic principle of system operation is the detection of a temperature difference between adjacent heated and unheated thermocouples.

As pictured in Figures 2 and 3, the HJTC sensor consists of a Chromel-Alumel thermocouple near a heater (or heated junction) and another Chromel-Alumel thermocouple positioned away from the heater (or unheated junction). In a fluid with relatively good heat transfer properties, the temperature difference between the thermocouple is large.

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Inadequate Core Cooling System Description Page 4 Two design features are provided to improve operation of the HJTC System. First, each HJTC is shielded to avoid overcooling due to direct water contact during two phase fluid conditions. The HJTC vith the splash shield is referred to as the HJTC sensor (see Figure 3).

Second, a string of HJTC sensors is enclosed in a tube that separates the liquid and gas phases that surround it.

The separator tube creates a collapsed liquid level that the HJTC sensors measure. The collapsed liquid level can be related to the average liquid fraction of the fluid in the reactor head volume above '

the upper fuel alignment plate. This mode of direct in-vessel sensing reduces spurious effects due to pressure, fluid properties, and .

non-homogeneities of the fluid medium. The string of HJTC sensors and ,

the separator tube are referred to as the HJTC probe assembly. <

b. Signal Processing The heated and unheated thermocouples in the IIJTC are connected in such a way that absolute and differential temperature signals are available. This is shown in Figure 4. When water surrounds the heated and unheated thermocouples, their temperature and voltage outputs are approximately equal. V,,,e, on Figure 4 is, therefore, approximately zero. In the absence of liquid, the heated and unheated thermocouple temperatures and output voltages become unequal, causing V,3_e, to rise.

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E POWER SYSTEMS CCv841cN (%Ntt=No 04 ELECTRICAL DIAGRAM OF HJTC 4 Inadequate Core Cooling System Description Page 5 The voltage output for each HJTC is processed by a microprocessor based system performing the following signal processing, surveillance, and heater power control functions:

Provides indication of the collapsed liquid level above the core alignment plate.

Provides a level output signal for trend recording to the operator via the SPDS (or pen recorder if desired).

Provides temperature indications of coolant in the upper plenum.

Provides test features for performing HJTCS operability and diagnostics.

Provides on-line surveillance of HJTCS to access operability.

Provides control of heater voltage to minimize HJTC internal heating after uncovery.

c. Operator Interface The HJTCS operator interface consists of an output indicator mounted on the cabinet, one 2 channel MCB vessel mimic, an output to a trend recorder, and an alarm output to the plant annunciator system. The level indication consists of a panel insert for a digital panel meter and an LED mimic that is capable of displaying the percent level of the steam-vater interface above the upper core alignment plate as indicated by the HJTC Probe assembly. The plant annunciator system alerts the operator that an ICC instrumentation channel has failed.

Fiber-optic data links are also provided for transmission of HJTCS data to the SPDS.

Enclosure 1 Inadequate Core Cooling System Description Page 6 C. RCITS Hardware Description.

A diagram showing the HJTCS hardware configuration for two channels is provided in Figure 1. Additionally, a functional block diagram for the HJTCS is shown in Figure 5. The hardware consists of the following major components: (1) sensing equipment, (2) signal processing equipment, (3) heater power controllers, (4) indicators and controllers, (5) serial fiber-optic data links, and (6) in-containment cable.

1. Sensing Equipment The HJTCS is composed of two channels of HJTC instruments. Each HJTC instrument channel is manufactured into a probe assembly consisting of eight (8) HJTC sensors, a seal plug, and electrical connectors (Figure

! 6). The eight (8) HJTC sensors are physically independent. They are located at eight levels extending from the reactor vessel head to the upper core alignment plate. The probe pressure retaining parts are designed using ASME Boiler and Pressure Vessel Code (BPVC) techniques.

However, the probe is not a Code stamped item since the code excludes instruments and small diameter fittings from the rules of the Code.

The probe assembly is housed in a stainless steel probe holder support tube that protects the sensors from flov loads and serves as the guide path for the sensors.

I 2. Signal Processing Equipment 1

Signal processing is performed by a microprocessor system. The system also controls heater power and performs on-line surveillance to determine open thermocouples and heater operability. The signal processor receives millivolt inputs from each of the eight (8) HJTC sensors. The device then processes these inputs and

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Enclosuro 1 ,

Inadequate Core Cooling System Description ,

Page 7 provides the following outputs: (a) level and temperature signals to the panel insert (display), (b) a level signal output for trend recording via the SPDS, (c) a signal to the plant annunciator system, (d) a signal to the heater controllers to modulate heater voltage l after uncovery, and (e) output signals to APCo's SPDS via fiber-optic data links (Described in Paragraph 5 below).

- i The signal processing equipment is qualified to mild environment [

conditions and is installed in the control room. ,

2 3. Heater Power Control f

In each channel, two heater controllers supply power to the HJTC heaters. Each heater controller serves a series group of four l J heaters. l 4

4. Indicators and Recorders I

The output of the signal processor is sent to a Class 1E seismically

(

qualified panel mounted insert and MCB mimic. A signal processor output is provided for trend recording via the SPDS. The panel j mounted insert (Figure 7) vill display percent level (above the core), l l provide for a arm indication, and, upon operator request, can display i

l the temperatures of each individual thermocouple. The digital display

{ vill be mounted on the microprocessor cabinet. A mimic display (LED  !

I i lights) is provided on the control board that indicates the status of each of the eight ilJTC sensors in each channel (i.e., covered with liquid or uncovered). Figure 8 provides a schematic of the mimic  !

display. The mimic display dimensions are 7 1/2" x 10". f

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Enclosure 1 Inadequate Core Cooling System Description Page 8

5. Serial Data Link to the SPDS Computer System The HJTC includes a serial, asynchronous data link to the SPDS computer. The transmission between the HJTC and the receiving computer vill be via fiber-optic cable which provides qualified Class q lE isolation. Interface between the data link and the receiving computer vill be via a standard RS-232 modem.

The HJTC software can transmit the following datas heated, unheated, and differential temperatures; reactor vessel levels; representative upper head temperatures; heater control signals; and the status of the reactor vessel level at each level.

6. ICC Honitoring System Cabinet Assembly Two (2) pre-vired, single bay cabinets (one for each channel) are provided for the ICC Honitoring system to house the signal processing equipment, heuter power controllers, and serial data links. Each cabinet is 30" vide by 36" deep by 90" higt. The cabinets are designed for both top (removable top coverplates) and bottom cable entry. The cabinet front doors permit viewing of the cabinet mounted HJTC display module when closed. Figure 9 shows the ICC cabinet configuration. The cabinets contain the processing hardware and signal terminations for SMH and CET functions. The ICCHS power requirements are 115 VAC 3 10%, 60 Hz 1 10%, 12 amps maximum, and 6 amps nominal. The ICCS heat load is 7,000 BTU /HR.

7. HJTC Probe Holder Support Tube The probe holder support tubes provide the guidance and support for l

j the HJTC probe assemblies. They are located in two (2) guide path shrouds. The location of the guide path shroud is in a spare Rod I cluster control guide tube position. The probe holder support tubes I

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Enclosure 1 Inadequate Core Cooling System Description Page 9 are attached to the interior of the guide path shroud structure that is conceptually identical to an existing rod cluster control guide tube. The probe holder assembly (see Figure 10), consisting of the guide path shroud and the probe holder support tube, is installed in the upper core support structure by removing a cover plate from the upper core support plate and the currently installed rod control cluster guide tube from the upper core support structure and then installing the probe holder assembly in the position ravly made available. The installed probe holder assembly is held in place utilizing the bolting and locking arrangement employed in the original design of the upper core support structure. The probe holder assembly, in essence, simply replaces the rod cluster control guide tube and rod cluster control drive shaft.

The probe holder assemblies have been judiciously located in positions such that the normal and postulated accident loadings on the probe holder are acceptable. The probe holder assembly is defined as an internal structure in accordance with ASHE Boiler and Pressure Vessel Code Subsection NG requirements and was fabricated to these requirements. The structural analysis to verify conformance to the stress and deflection criteria vas completed for the vessel and head modifications and probe installation.

8. Reactor Pressure Boundary Hodifications l

l l

Modification of the reactor vessel head pressure boundary at two spare control element drive mechanism locations was required to form a penetration for each of the two HJTC probe assemblies. Figure 11 shows the required configuration.

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i Enclosure 1 Inadequate Core Cooling System Description

Page 10  !

j The Farley Units 1 and 2 HJiC nozzles are located near the periphery 1

of the array of head nozzles and are therefore accessible at a lov t

elevation. A capped latch housing extension, that mates to the  !

t j reactor head nozzle in the same fashion as the existing closure and i

! that extends upward, was velded to the quick disconnect Grayloc

• closure assembly. The quick disconnect Grayloc closure was velded to [

! the capped latch housing extension to form the HJTC pressure boundary assembly. The blind hub of the flange set is configured to accept the HJTC probe seal plug and packing rings. It also contains a vent plug to ensure proper venting of the nozzle. The thermal sleeve extends ,

dovnvard into the head area and overlaps the upper section of the  !

probe holder, thereby shadoving the probe from direct cross flov.

l The design of the Grayloc flange is such that the HJTC probe l assemblies can be removed or installed through the penetration without [

removing the reactor vessel head. f

9. HJTC Handling Hardware l

The length of the HJTC probes is approximately twenty-five feet. As a f result, outages in which the reactor vessel head is removed vill (

require that the probe be separated from the head. This is i accomplished by separating the Grayloc flange and by disconnecting the probe from the Grayloc blind hub. The probe electrical connectors are then covered with a leaktight bullet nose and the probes are left in [

the upper internals package during outages. Special handling i equipment, other than the watertight bullet noses, is not required for j the Farley Units because the probe assemblies are short enough to be [

i left in the upper internals package.

Enclosure 1  :

Inadequate Core Cooling System Description  !

Page 11 t

f

10. Accuracy The accuracy of the indicated temperature for the HJTCS is i 7.6*F (RSS method) from 70 F to 530*F and i 15*F at 1800*F. The accuracy 4

between 530*F and 1800*F is a linear ramp between the accuracies f defined above for these two temperatures. During and after design I basis event conditions, the temperature indication accuracy is i 23* F 1 from 70*F to 530*F and i 26.3*F at 1800*F.

l The measurement accuracy described above accounts for all f uncertainties within the instrument loop (i.e., the thermocouple and  !

4 its accuracy, HJTCS cabling, signal processing, and display l uncertainties).

j D. RCITS In-Containment MI Cable Description l The cable provided was designed to meet the criteria specified and tests i

imposed by IEEE Standards 323-1974, 383-1974, and 344-1975 and

! 10CFR50.49.

I f

l Mineral Insulated Cable (HI Cable) is a 1/4 inch, stainless steel l sheathed multi-conductor cable that is fully qualified to the

' post-accident environment at Farley Nuclear Plant. Copper vire is 18 gauge and Chromel-Alumel vire is 28 gauge. It is hermetically sealed through an all-velded construction technique and this, together with the l

j inorganic materials used, provides a very high tolerance for abnormal l temperatures and pressures and has crinimal susceptibility to radiation t

j damage. The cable has an inner copper liner used to reduce l electromagnetic interference and is factory terminated with qualified,

! quick-disconnect type multipin connectors. The outer jacket consists of fully annealed stainless steel that may be formed into bends as tight as a 2" bend radius to facilitate installation. Mounting of the cable utilizes means identical to those used in instrument sensing i lines.

l l

Enclo:urg 1 Inadequate Core Cooling System Description Page 12

1. Reactor Cavity Cable Each HJTC cable set is compriced of one cable section from the HJTC probe to the poolside disconnect panel. This set consists of sixteen (16) cables, one for each sensor in two (2) HJTC probes (See cable 1 of Figure 12). The cable is required to be supported every five (5) feet except at the connectors where a support within three (3) feet is required. For ease in routing the cable, all eight (8) cables of one train can be bundled together and routeo as one group.

2. Containment Cable Each cable is comprised of one section from the poolside disconnect panel to the containment penetration (refer to cable 2 of Figure 12).

Routing and handling is the same as the reactor cavity cable described above. Hating half connectors that can be installed in penetration assemblies for containment penetrations are also included.

E. RCITS Softvare Description The level logic is performed on each of the sensor reference junction and differential temperature signals in the channel. Vhen the magnitude of both the sensor's differential output and reference junction output is less than their respective setpoints, the output from the level logic vill indicate the presence of liquid at the respective sensor. If the hugnitude of a sensor's dif ferential output or reference junction output reaches or exceeds a high preset value, then the output signal from the level logie vill indicate that the liquid level has dropped to a level lover than the respective sensor, l

Connectors 3 I

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m Penetration Q CABLE SECTION 10Et4TIFICATI0tl

1. Cable to Pool-Side Disconnect

2. Cable to Penetration Notes

• Each cable section consists of 5 wire cabling

............ Refueling Disconnect Points l.

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" _'J POWER HJTC M1 CABLE LAYOUT 12 SYSTEMS ca .veieniae m

Encicsuro 1 Inadequate Core Cooling System Description Page 13 l

l III. Description of CET System l

i A. Design Features of CET The Core Exit Thermocouple (CET) System provides the transmission of thermocouple signals, signal processing and display to allow the operator to monitor core exit temperature. The cabling used to transmit signals is similar to RCITS cabling and may be routed with RCITS cabling. The signal processing is performed in the processor cabinet that s'ao does the signal processing for RCITS. The digital display module is similar to that provided for RCITS.

B. Functional Description of CET The CET data is provided to indicate and trend the core heatup in the event of a core uncovery and to indicate and trend the cooldovn during subsequent core recovery. Fuel clad temperature is representative of core temperature. Due to thermal coupling between the cladding and liquid or steam temperature, it is sufficient to measure the temperature at the exit of the core to provide an indication of core temperature.

The CET system uses the existing thermocouples located in the upper guide structure just above the core.

CET inputs are divided between the two channels so that each channel sees a representative distribution of CET temperatures.

Out-of-range thermocouple values can be manually defeated by the operator. From among the valid CET temperature indications, the highest CET temperature is calculated for display and for input to the SMH calculation. All CET temperatures are available for display on command. All CET temperatures vill be data linked to the SPDS computer.

Enclcsuro 1 Inadequate Core Cooling System Description Page 14 C. CET Hardware Description The existing connectors of the individual thermocouples vill be replaced with qualified hermetic connectors for mating with the mineral insulated cable connectors. This CET connector upgrade consists of removing the existing thermo-electric connectors and installing C-E's qualified tvin pin connector. MI cable is used to carry the T/C signals from the reactor vessel head to the cont 'nment penetration.

Each LET cable set is comprised of 3 cable sections. The first cable section consists of a short transition cable which provides connectors for mating with the individual thermocouples. The leads from these connectors are combined into a single multi-connector cable, terminated at the top in a multipin connector (refer to cable 1 Figure 13). This cable section is designed to fit under the refueling bullet noses for the CET's so that during refueling operations only the multipin connector is disassembled leaving the tvin pin CET connectors untouched.

This results in reduced refueling time and man-rem exposure since only the multipin connectors need be disconnected instead of each CET tvin pin connector. It also further reduces the potential of damage to the individual CET connectors. The second cable section is routed within the head area cable support structure and interfaces with the transmission cable and containment cable (refer to cable 2, Figure 13).

This section is disconnected at both ends and removed from the head area cable support structure during refueling. A third, permanently installed, cable section vill be provided to run from the poolside disconnect to the containment penetration. (Refer to cable 3. Figure 13).

4 i

+

Enc 1csure 1 Inadequate Core Cooling System Description j Page 15

) '

< t i The CET Processor is comprised of two independent and redundant [

channels (A and B) which meet the isolation and qualification I standard for a Class 1E system. Each channel contains microcomputer-

! based electronics to process and display CET temperatures. The CET processor meets the seismic and environmental qualification criteria set forth in IEEE Standard 323-1974, IEEE Standard 344-1975, and  !

l i 10CFR50.49. The system employs both a continuous, on-line diagnostic routine and on-demand caiibration logic to ensure l software reliability and hardvarc maintainability. The data link shall provide the SPDS with all CET values in a timeframe compatible j vith SPDS operation. The following describes the major instrumentation comprising the CET Processor. l

[

q 1. Microprocessor chassis for processing all the Inputs / Outputs of the CET I l System, along with thermocouple reference junction temperatures for ,

s thermocouple compensation.  !

l

2. Fiber-optic RS232C data links (with fiber optic modems) for l

communications between the CET Processor and the SPDS. These data links  !

meet the isolation requirements of IEEE-279.

l l

3. Individual, dedicated digital panel meters, located on the main control  !

board, are used for displaying CET parameters conveniently to the

operator.

I

)

4. Class 1E contact alsrm outputs and Class 1E analog trend recorder I l

l outputs for alarming and recording the highest valid CET temperature. [

! (Analog outputs are not utilized since trcnding and alarms are indicated  !

on the SPDS display.)

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Encicsuro ?

Inadequate :: ore Cooling System Description i Page 16 l D. CET In-Containment HI Cable Description i

1. Reactor Cavity Cable 1

Mineral Insulated (MI) Cable for the CET signals which is similar in construction to MI cable for the RCITS vill be utilized.

I Each CET cable set vill carry signals from the thermocouples in sufficient quantity to monitor the number of core exit thermocouples as indicated l'elort b e. InJtrument Ports 4 l

No. of Thermocouples Per Port 12 & 13 Total No. of Thermocouples 51 l

Type of Cables 8 & 10 vire j

i

' Each reactor cavity CET cable 'et is comprised of 2 cable sections.

l Copper vire is 18 gauge and Chromel-Alumel vire is 28 gauge. The l

! first cable section consists of a short section which provides connectors for mating with the individual thermocouple connectors.

The leads from these cennectors are combined into a single l'

multi-cennector ca,ble, terminated at the top in a multipin connector (refer to cable 1 Figure 13). This cable section is designed to fit under the refueling CET bullet noses so that during refueling i

operations only the multipin c.onnector is disassembled leaving the I

twin-pin CET connectors untouched. Bullet nose assemblies used to protect tha "T c',nnectors during refueling vill be lengthened to f

! accommodate 'J.ie short first MI cable section. The second cable f section provides the transition from the refueling bullet nose l

disconnect along the reactor cavity to the poolside di9 connect (refer to cable 2 Figure 13). This section is disconnected at both ends during refueling and remains with the cable support structure.

L

Enclosuro 1 Inadequate Core Cooling System Description Page 17 Since the cable is semi-rigid, no external cable support structure is required for the short segment of this cable section which traverses the refueling cavity. A third section (beyond the reactor cavity) runs from the poolside disconnect to the containment penetration.

The existing connectors of the individual thermocouples vill be replaced with qualified hermetic connectors for mating with the mineral insulated cable connectors. This CET connector upgrade

consists of removing the existing Thermo-Electric type connectors and installing C-E's qualified tvin-pin connectors that have been tested to meet the applicabla post-accident containment environments.

I

2. Containment Cable Each Mineral Insulated cable is comprised of one section from the poolside disconnect panel to the containment penetrations (refer to cable 3 of Figure 13). Routing and mounting is the same as for the HJTC containment cables.

E. CET Softvare Description i

The CET software consists of calculating the highest and next highest CET temperatures per quadrant and the highest CET temperature overall.

IV. Description of SHM p I

A. Design Features of SHM The "ubcooled Margin Monitor (SMM) is an on-line microcomputer based

• system which uses reactor coolant process signals to provide a continuous indication of the margin from saturation conditions. The l

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CABLE SECTION IDENTIFICATION

@ Head Area Transition Cable

@ Head Area Cable

.@ Containment Cable THERMOCOUPLE LEAD IDENTIFICATION

@ Pressure Tube

@ Expoiod T/C Lead NOTES:

CABLE h GATHERS T/C LEADS FROM FOUR OR FivE INOlVIDUAL CET ASSEMBLIES EACH CABLE SECTION CONSISTS OF THE APPROPRIATE NUMBER OF 8 WIRE AND 10 WIRE CABLING REFUELING DISCONNECT POINTS l,

Figure SS S CET MI CABLE LAYOUT 13 ceuentcN Ect(=NG i<

Enclosuro 1 Inadequate Core Cooling System Description Page 18 SMM provides information for the operator to determine the loss of subcooled margin which is the first phase of an Inadequate Core Cooling scenario. In addition, active fuel uncovery is confirmed by the indication of superheated steam temperatures. The operator is provided continuous indication of either the pressure or temperature margin from saturation. The data-link vill transfer all RCS pressures used in the algorithm to the SPDS.

B. Functional Description of SMM The saturation temperature margin is the difference between the measured temperature of the reactor coolant and the sat. ration temperature. The saturtt

• n teaperature is calculated from the minimum primary system pressure input. A maximum or representative temperature input is used for the measured value.

Temperature saturation margin calculations are performed for two major locations: 1) the highest primary loop RTD temperature and 2)

I a core exit temperature.

! The operator can select (via a pushbutton) either RTD or CET saturation temperature margins for display at the operators display j panel. All input temperatures and pressures vill be available on operator command.

l

Enclosuro 1 Inadequate Core Cooling System Description Page 19 C. SHH Hardware Description The Subcooled Margin Monitor consists of a digital display module, a microprocessor, plus the interconnecting cabling between the digital display and microprocessor. The panel display module face measures five inches vide by four and one quarter inchas high. The microprocenor function is integrated into the ICrHS microprocessor.

The SHH provides outputs to alarms and trend recorders as well as data links to the SPDS. (Analog outputs are not utilized since trending and alarms are indicated on the SPDS display.)

V. Integration of RCITS, CET and SMH into a Total ICCM System A. Introduction Inadequate Core Cooling (ICC) Honitoring System is a safety grade processing and display system which is qualified to Class lE standards. The ICC Monitoring System addresses the NUREG-0737 ICC instrumentation processing and display requirements. The ICC Monitoring System design has been verified and tested to Class lE criteria to ensure that the required standards of hardware and software reliability are achieved.

The main objectives of the ICC Honitoring System include:

C1. ass 1E inadequate reactor core cooling instrumentation signal processing Class 1E display of inadequate reactor core cooling instrument signals Isolation and data liaking of Class 1E signals to Alabarna Pover Company's SPDS computers

Enclcsuro 1 Inadequate Core Cooling System Description Page 20 The ICC Monitoring System processes Class lE signals including those from the SHM, the HJTCS, and CET's. The ICC Monitoring System vill accommodate the t; pes of thermocouple and RTD instrumentation used at Farley Nuclear Plant for ICC monitoring.

The ICC Honitoring System integrates the subcooled/superheat margin, reactor coolant inventory, and core exit temperature processing and  ;

display into one system. Figure 14 depicts the locations of the ICC sensor locations. Additionally, Table 1 provides the function, range, number of channels, and outputs for each ICO sensor.

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TABLE 1 INADEQUATE CORE COOLING MONITORING SYSTEM PROCESSING AND DISPLAY PROCESSING g FUNCTION SENSORS RANGE #/ CHANNEL OUTPUTS Maximum HJTC HJTC Unheated Junction CRJ'-2300*F 1 1) Maximum Temper-Temperature Temperature ature.

Maximum Individual CRJ*-2300*F 1 1) Maximum CET Temperature CET Temperatures Temperature Reactor Yessel HJTC Probe including: CRJ*-2300*F 16 1) Liesid level (Top Liquid Level (Top Heated Junction T/C Temp., of core to top of of core to top of Unheated Junction T/C head) head) Temperature; Differential Temp. (Level) 2) HJTC Sensor Temperature

3) Maximum HJTC unheated junc. tion temperature.

Core Exit Core Exit Thermocouples CRJ*-2300*F 32 (maximum) 1) Individual CETC Temperatures (CETC) Temperatures Temperatures

2) Maximum CETC Temperature Saturation Margin Hot Leg RTD Temp. 0-750 *F 3 1) RCS Loop Temperature Cold Leg RTD Temp. 0-750 *F 3 margin (subcooled Max HJTC Unheated to superheat)

Junct. Temp. CRJ'-2300*F 1 Maximum CET Temp. CRJ*-2300*F I 2) Core Exit Tempera-Pressurizer Pressure 1700-2500 psig 1 ture Margin RCS Pressure 0-3000 psig 2

3) RCS Pressures (data link only)

• CRJ - Cold Reference Junction Thermocouple (Ambient Poom Temperature of the Cabinet)

L l

t arrivants 2 Ilmergency nesponse Guidelines and Procedure Setpoints for the Heated Junction hervoccuple System at Parley Nuclear Plant ,

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Guideline ES-0.3 l 1

1. Try to Restart an RCP

4. Check BOTH of the following a. Perform the following:

HJTCS indications: ,

1. UpperHead-(8)% 1. Increase PR2R level ta (1)% i using charging and letdown

. 2. Upper Plenum - (9)% 2. Establish subcooling greater than (2)'F using steun dump

5. Check HJTCS Upper Plenum Repressurize RCS to maintain HJTCS i

Indication - GREATER THAN (5)% upper plenum indication greater than (5)%. Return to Step 3.

11. Continue Cooldown of Inactive Portion of RCS a.

b.

c. BOTH of the following HJTCS 1

indications: ,

i

1. Upper Head - (8)%

2. Upper Plenum - (9)%

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Grideline E-3

35. Check RCP Status:

a. RCPs - AT LEAST ONE RUNNING a. Try to start one RCP:

1

1. IF ANY one of the following HJTCS indications is observed:

o Upper Heed - LESS THAN (26)%

o Upper Plenum - LESS THAN (32)%

i THEN perform the following:

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Guideline ECA-1.1

13. Verify Adequate SI Flow:

a. HJTCS upper plenum a. Increase S! flow to maintain indication - GREATER HJTCS upper plenum indication 3 THAN(10)% greater than (10)%

18. Depressurize all Intact SGs to Inject Accumulators as Necessary:

a. Dump steam to condenser as a. Manually or locally dump steam from necessary to maintain HJTCS intactSG(s)asnecessaryto upper plenum indication at maintain HJTCS upper plenum (10)% indicationat(10)%:

o Use PORY

- or -

o (Enter plant specific means)

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. Guideline ECA-3.2

16. Control Charging Flow to Waintain Reactor Coolant Inventory by Naintaining HJTCS Upper Plenum Indication:

3

. o One RCP running - GREATER THAN (32)%

o NoRCPsrunning-GREATERTHAN(33)%

20. Verify SI Flow Not Required

a. a. ,

b. Che:k HJTCS upper plenum b.

indication: '

o One RCP running - GREATER THAN (32)%

o No RCPs running - GREATER THAN (33)%

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0273v.10422686 ,

1

Foldout for Guideline ECA-3.2

1. 51 REINITIATION CRITERIA Manually operate $1 pumps as necessary if EITHER condition listed below occurs: -

o Core exit TCs - INCREASING o HJTCS upper plenum indication:

o One RCP running - GREATER THAN (32)%

o No RCPs running - GREATER THAN (33)%

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1. 51 REINITIATION CRITERIA Manually operate SI pumps as necessary if EITHER condition listed below occurs:

o RCS subcooling based on core exit TCs - LESS THAN (10)*F [(11)'F FOR ADVERSE CONTAINMENT)

, o HJTCS upper plenum indication - LESS THAN (12)%

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. HJTCS LEVEL VALUES .

HJTts Upper Head Values

1. Value indicating upper head region full: 100%; ccrresponds to RVLIS Upper Range Value for indicating upper head full.

H]TCS Voper Plenum Values l 1. Value indicating upper plenum region full: 100%; corresponds to RVLIS j Upper Range Value for indicating upper head full.

2. Value which ensures that RCS void fraction is less than 25'; with 1 RCP running: 12J;correspondstoRVLISDynamicRangeValueforindicating level of top of hot legs with RCP(s) running.

3. Value which is top of het legs, plus uncertiinties: 4.,4j;correspondsto RVLIS Full Range Value for indicating top cf hot le;s during natural circulation.

4. Value which is top of core, plus uncertainties: Oj;correspondstoRVLIS i Full Range Value for incicating top of core.

1

5. Value which ccrresponds to 3.5 feet above bottom of active fuel in core

! with zero void fraction plus uncertainties: OJ;correspondstoRVLIS j Full Range Value for level 3.5 feet above active fuel region (for use in l

FR-C.1 and FR C.2 only).

6. Value which is above the top of active fuel in core with zero void

! fraction plus uncertainties: g;correspondstoRVLISFullRangeValue

) for tcp of active fuel on core with zero void fraction plus uncertainties.

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D4 CLOSURE 3 RESPONSE TO NUREG-0737, ITEM II.F.2, ATTACHMENT 1

1. NRC Request Provide diagram of core-exit thermocouple locations or reference the generic description if appropriate.

APCo Response The actual core-exit thermocouples have not been replaced. The thermocouples are the same type, have the same functional characteristics, and are in place at the same core locations as previously described to the NRC in Alabama Pover Company letter dated July 17, 1980. The inside containment cabling, electrical penetrations, outside containment cabling, processor, and displays have all been upgraded. The transition cables which connect the thermocouple leads to the nev qualified inside containment cabling vere installed during the Unit 2 fifth and Unit 1 eighth refueling outages.

2. NRC Request Provide a description of the primary operator displays including

a. A diagram of the display panel layout for the core map and a description of hov it is implemented, e.g., hardware or CRT display,

b. Provide the range of the readouts.

c. Describe the alarm system.

d. Describe hov the ICC intrumentation readouts are arranged with respect to each other.

APCo Response The core-exit thermocouple primary display is a CRT based display that consists of a two dimensional core map that presents thermocouples in their positions relative to core quadtants and core coordinates (see Figure 1). The range of thermocouple readouts is frop ambient temperature (reference junction temperature) to 2300 F. The core-exit thermocouple values are disp quality values less }han 700}ayed F, orange onfor thegood corequality map in cyangreater values for good than or equal to 700 F but less than,1200 F. and red for good quality values greater than or equal to 1200 F. Bad therrocouples have a value of "XXXX" displayed with a designator for bad quality. Vhen at leas) five thermocouples display a value of greater than or equal to 1200 F the SFDS status tree for Core Cooling outputs a "JEOPARDY" or red path visual alarm. When there are at least five thermocouples

Enclosuro 3 Fage 2 greater than or equal to 700*[ but less than five thermocouples greater than or equal to 1200 F the SPDS status tree for Core Cooling outputs a "SEVERE CHA1.LENGE" or orange path visual alarm when inadequate subco711ng margin exists. Vhen inadequate subcooling margin exists bv. thpre are not tive or more thermocouples greater than or equal to 700 F a "NOT SATISFIED" or yellow path visual alarm occurs. No audible alarm exists for the CRT based displayn.

In addition to the core map previously described, dislays exist that list all thermocouples on a per quadrant basis and also present their associated cere siap coordinates. Hard copy and trend capability exists for the primary display. There also exists a two page point detail display for each thermocouple that contains information intended principally for instrumentation maintenance purposes (e.g.,

calibration).

3. NRC Request Describe the implementation of the backup display (s) (including the subcooling margin monitors), hov the thermocouples are selected, hov they are checked for opersbility, and the range of the display.

APCrs Response The core-exit temperature backup displays are two (one per channel) four digit displays mounted on the main control board. The displays contain three push button svitches which are used to 1) display the highest core-exit temperature value, 2) enter submodes to query the system, and 3) acknowledge alarms. The range for the core-exit temperature display ls from ambient temperature (reference junction temperatute) to 2300 F. The processor vill pignal an alarm on the display if the highest CET value exceeds 700 F. The response time 'or displaying a selected CET value is no greater than two seconds. The subcooling margin monitor displays are also located on the main control board and exist on CRT based displays as well. There are two (one per channel) four digit digital displays that can display subcooling margin based on CET's or loop vide-range RTD's.

4. NRC Request Describe the use of the primary and backup displays. Vhat training vill the operators have in using the core-exit thermocouple instrumentation? Hov vill the operator knov vhen to use the core exit thermocouples and when not to use them? Reference apprentiate emergency operating guidelines where applicable, s _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - . _

Enclosuro 3 Page 3 APCo Response The displays for core-exit temperature are used to verify the highest core-exit therucouple value ist a) within a specified range, b)

! above or behov a specified value, or c) trending in a certain direction. Operations personnel are insnucted on the use of the

upgraded core-exit temperature monitoring instrumentation during I operator requalification training. The plant simulator has been modified to reflect the new system as well. The plant emergency t

operating procedure specifies to the operator when to monitor l core-exit temperature.

5. NRC Request

]

Confirm completion of contrc,1 room design task analynis applicable to

! ICC instrumentation. Confirm that the core-exit thermocouples meet the criteria of NUREG-0737, Attachment 1 and Appendix B, or identify

and justify deviations.

[

APCo Response Alabama Power Company vill complete the control room design reviev i task analysis for the RCIT.i prior to implementing revised emergency operating procedures, which vill be upon receipt of plant-specific 5

approval from the NRC. The procedures and equipment vill be validated i using the plant simulator. The criteria of NUREG-0737, Attachment 1

, and Appendix B, are satiefied. The specific responses to NUREG.0737, l Attachment 1 and Appendix B, are included in Enclosures 4 and 5 of this letter, respectiva1y.

l i

i l 6. NRC Request

! Describe what parts of the system are povered from 1E power sources, j and how isolation from non-1E equipment is p.0vided. Describe the

power supply for the primary display. Cleatly delinerte into tvo categories which hardware is included up to the isolation device and which is not.

APCo Response The enre-exit temperature instrumentation is povered by clo. 1E pover sources. The cabling, processor and backup displays are all class lE. The primary display is not povered by a class 1E source. The isolation between the class IE and non-class 1E supplied equipment is performed by a fiber-optic data link batveen the ICC instrumentation processor and the Safety Parameter Du play System processor which generates the primary display. A description of the requirements met for isolation and class lE power sources is provided in Enclosure 5.

Enclosure 3 Page 4

7. NRC Request Confirm the environmental qualification of the core-exit thermocouple instrumentation up to the isolation device.

APCo Response The upgraded core-e;.it temperature instrumentation is environmentally qualified from the *.rcnsition cables that connect to the theraccouple leads at the reactor vessel instrument ports to the processor cabinet in the main control roos. This system includes the cabling inside containment, the electrical penetrations, and the cabling from the electrical penetrations to the processor cabinet. A description of the environmental qualification requirements that were met is provided in Enclosure 5.

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ENCLOSURE 4 The criteria of NUREG-0737, Attachment 1, are satisfied for the upgraded core-exit temperature instrumentation. The specific items of NUREG-0737, Attachment 1, are addressed below:

Ites 1 l Thermocouples located at the core exit for each core quadrant, in conjunction with core inlet temperature data, shall be of sufficient number to provide indication of radial distribution of the coolant enthalpy (temperature) rise across representative regions of the core. Power distribution symmetry should be considered when determining the specific number and location of thermocouples to be provided for diagnosis of local core problems.

Response

A thorough description of the core-exit thermocouples was provided by Alabama Power Company in letter dated July 17, 1980. The upgrades to the core-exit temperature instrumentation have no effect on the locations of the thermecouples. See the response to NRC Request No. 1 of Enclosure 3.

Item 2 There should be a primary operator display (or displays) having the capabilities which follov (a) A partially oriented core map available on demand indicating the temperature or temperature difference cross the core at each core exit thermocouple location.

(b) A selective reading of cor, exit temperature, continuous on demand, which is consistent with parameters pertinent to operator actions in I connecting with plant-specific inadequate core cooling procedures.

For example, the action requirement and the displayed temperature might be either the highest of all operable thermocouples or the average of five highest thermocouples.

(c) Direct readout and hard-copy capability should be available for all thermocouple Jemperatures. The rang

• should extend from 200 F (or less) to 1800 F (or more).

(d) Trend capability showing the temperature-time history of representative core exit temperature values should be available on demand.

(e) Appropriate alarm capability should be provided consistent with ,

operator procedure requirements.

(f) The operator-display device interface shall be human-factor designed to provide rapid access to requested displays.

=

Enclosuro 4 4

Page 2

Response

See the response to NRC Request No. 2, 3, 4, and 5 of Enclosure 3 for a description of the primary operator display. See response to Item 4 belov for description of human-factor design considerations.

Item 3 A backup display (or displays) should be provided with the capability for selective reading of a minimum of 16 operable thermocouples, 4 fiom each core quadrant, all within a Jime interval no grepter than 6 minutes. The range should extend from 200 F (or less) to 2300 F (or more).

i l

! Response See the response to NRC request No. 3 of Enclosure 3 for a description of ,

the backup displays.  :

Ites 4 [

The types and locations of displays and alarms should be determined by performing a human-factors analysis taking into considerations (a) the use of this information by an operator during both normal and abnormal plant conditions.

J (b) integration into emergency procedures, 1

(c) integration into operator training, and l (d) other alarms during emergency and need for prioritization of alarms.

Response

The displays were designed with human-factors engineering practices applied.

The NUTAC document for Control Room Design Review provided guidance for these practices. The design of the displays and alarms, as well as the physical arrangement on the main control board, was reviewed by Alabama  ;

Power Company's human-factors engineering consultant. The integration of the system into the emergency procedures vill be validated by a task analysis of the system. Operator instruction vill incorporate the nev ICC instrumentation into requalification training for licensed reactor I operators.

Enclosure 4 Page 3 Ites 5 The instrumentation must be evaluated for conformance to Appendix B, "Design and Qualification Criteria for Accident Monitoring Instrumentation", as modified by the provisions of items 6 though 9 which follow.

Response

The specific criteria of Appendix B to NUREG-0737, II.F.2, is addressed in Enclosure 5 to this letter.

Item 6 The primary and backup display channels should be electrically independent, energized from independent station class lE power sources, and physically separated in accordance with Regulatory Guide 1.75 up to and including any isolation device. The primary display and associated hardware beyond the isolation device need not be class lE, but should be energized from a high-reliability power source, battery-backed, where momentary interruption is not tolerable. The backup display and associated hardware should be class 1E.

Response

The two backup displays are electrically independent and physically separated from each other in accordance with Regulatory Guide 1.75. They are energized from class 1E power sources. The primary display is supplied by a highly reliable, battery-backed power supply and is completely independent from the backup displays.

Item 7 i The instrumentation should be environmentally qualified as described in Appendix B. Item 1, except that seismic qualification is not required for the primary display and associated hardvare beyond the isolator / input buffer at a location accessible for maintenance following an accident.

Response

The ICC instrumentation is environmentally qualified as stated in response

' to NRC Request No. 7 of Enclosure 3. Further reference to environmental qualificttion vill be made in Enclosure 5 (response to NUREG-0737, Appendix B). The ICC instrumentation system is seismically qualified except for the primary display and associated hardware beyond the isolator.

1 4

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Enclosure 4 Page 4 Item 8 The primary and backup display channels should be designed to provide 99%

availability for each channel with respect to functional capability to display a minimum of four thermocouples per core quadrant. The availability shall be addressed in technical specifications.

Response

The ICC instrumentation primary and backup displays were designed for an availability factor of at least 99 percent.

Item 9 The quality assurance provisions cited in Appendix B, item 5, should be applied except for the primary display and associated hardware beyond the isolation device.

Response

- The ICC instrumentation system was designed and fabricated under an approved j quality assurance program. The specific reference vill be provided in Enclosure 5.

4

I ENCLOSURE 5 Listed below are the specific responses to NUREG-0737, II.F.2, Appendix B:

1. Environmental Qualification The ICC instrumentation system is environs:entally qualified per the design requirements of R.G. 1.97 Category 1, IEEE-323-1974, R.G. 1.89, and 10CFR50.49. All equipment located inside containment or in areas of recirculated fluids is environmentally qualified for both normal and design basis accident conditions. There are no deviations from these requirements. ,

2. Single Failure Analysis Each of the two channels of the ICC instrumentation system constitutes a redundant division of this safety related system. Electrical independence of the two redundant divisions is achieved through several Leans: a) independent processor cabinets, b) independent power suppli u ,

c) independent sensors and displays, and d) independent interconnecting cables, c_ble trays, and penetrations.

The two channels are physically separated in accordance with the requirements of R.G. 1.75. Two separate routes which are protected from high energy line breaksi are used from reactor to the processor cabinets.

In addition, the ICC instrumentation system satisfies criteria set forth in NUREG-0696 regarding uninterrupted performance during and subsequent to events expected to occur during the life of the plant including ear tl.riakes .

Given the features of the design described above, it can be concluded that a single failure of any component (sensor, cable, penetration, cabinet, display) in one redundant channel vill not prevent the other redundant channel from properly performing its intended function.

j Similarly, failure of the power supply associated with one redundant channel vill not adversely impact the other channel.

Each of the redundant ICC insttumentation system processors has a continuous on-line diagnostic routine that checks both hardware and i software. The diagnostic system provides error and failure messages to the operators in the main control room. For example, a processor failure is annunciated by the plant annunciator. The on-line diagnostic allovs

the operator to deduce the actual plant conditions should a failure occur l

in one channel.

Reactor coolant system pressure and temperature inputs to the subcooling margin monitor portion of the ICC instrumentation system originate in the existing W 9ndant class 1E process instrumentation cabinets (train A and B). Ir, order a have the subcooling margin monitor of each train read the sr.me, analog temperature and pressure data from both trains are t

proviled as inputs to each train of the ICC instrumentation system.

Opposete train inputs are isolated as described in item 9, such that a single failure vill not prevent the ICC instrumentation system from performing its intended function.

t ,

Enclosure 5  ;

Page 2 l

3. Class IE Power Source i

The ICC instrumentation system is a class 1E processing and display l system, designed to provide two independent and redundant channels (A and B) of safety grade display instrumentation.

A single bay cabinet is provided for each channel which houses the signal and power terminations for the processing equipment and heater controllers for the HJTC. The processing equipment provides power to the digital displays and the heater controllers. The heaters use the same power source as the processing equipment.

The main power supply to each of the two channelized ICC instrumentation system cabinets is provided from separate class 1E train oriented 120 VAC distribution panels (see Figures 2 and 3 attached). Each distribution panel is supplied power from a separate train oriented class lE inverter.

During normal operation the inverter power is derived from a class IE AC source (600V class 1E MCC backed-up by a class 1E diesel generator). In the event of the source failing, a class 1E DC source (provided by a class 1E emergency battery) instantly feeds power to the inverter until the AC source returns, and as such, the inverter constitutes an uninterruptable source of AC pover.

It should be noted that the inputs to the subcooling margin monitor are generated in the class 1E process control cabinets. Power supplies to these cabinets are provided by the channelized 120V class 1E vital AC distribution panels, which have class IE battery and diesel back-up.

4. Availability Prior To An Accident The ICC instrumentation system was designed to have a 99 percent availability factor. The system can be easily checked at power without affecting plant operation.

S. Quality Assurance The Combustion Engineering quality assurance program incorporates the guidance endorsed by Regulatory Guide 1.97, Rev. 3.

6. Continuous Indications The ICC instrumentation system includes two independent class 1E backup displays and one non-class 1E primary display. The processor continuously updates the information and generates a new display every three seconds.

Enclosure 5 Page 3

7. Recording of Instrument Outpup The primary display has the capability to maintain a historical log of values, and display them to the operator either on the CRT screen or a printed copy. The ICC system processor also has the capability to output to a trend recorder if needed.

8. Identification of Instruments The ICC instrumentation system displays vill be located on the reactor panel of the main control boards. Each display is clearly labeled by function.

9. Isolation Signals that are transmitted from the ICC instrumentation system to non-class 1E equipment are isolated as follovst

1. Safety Parameter Display System (SPDS) Computer Isolation between the ICC instrumentation system and the SPDS computer is accomplished via a fiber-optic data cable.

i 2. The Plant Annunciator Isolation between the ICC instrunentation system and the plant annuraf ator is accomplished by a class 1E relay (coil to contact isolation). The class 2E telay is located in the ICC instrumentation system cabinet.

In addition to the isolators dir:ussed above, class 1E analog isolators are provided for the opposite train analog inputs provided to each train of the ICC instrumentation system. This isolation is accomplished as follows:

As indicated in response to item 2 above, reactor coolant system pressure and temperature data from both trains of process instrumentation are provided as inputs to each train of the ICC

' instrumentation system. The opposite train inputs are isolated by class 1E transformer modulation type isolators that are located in the process control caisinets. This isolation ensures that a fault in the process control cab' nets cannot affect both trains of the ICC Instrumentation system.

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ENCLOSURE 6 NRC Request Discuss the spacing of the sensors from the core alignment plate to the top of the reactor vessel head. How would the decrease in resolution due to the loss of a single sensor affect the ability of the system to detect an approach to ICC?

APCo Response The locations of the hr ed junction thermocouple sensors were choser.

to provide level indicat.on at important physical structures within the reactor vessel. The first sensor was located as close to the top of the vessel as possible in order to detect possible void formation in the head. The next two sensors vere placed just above and just below the upper support plate in order to detect differences in draining rates between the upper head and upper plenum regions. The next sensor was placed midway between the upper support plate and the top of the hot leg. The next three sensors vere located at the top, midplane, and bottom of the hot leg in order to detect possible void formation at the hot leg. The bottom sensor was placed as close as possible to the core. The loss of any one of these sensors vould not diminish the operators ability to detect or trend vater level since there are two independent channels of reactor vessel level available.

See Figure 4 f.or a depicticn of t'e sensor locations as displayed by the reactor vessel level mimic display.