ML20125B291

Transient W/Failure to Scram

ML20125B291
Person / Time
Site:	LaSalle
Issue date:	10/10/1979
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20125B289	List: ML20125B285 ML20125B291
References
LGA-18, PROC-791010, NUDOCS 7910290292
Download: ML20125B291 (9)

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,, 1 TR AfJS IENT WITH FAILUuE TO SCRAM i

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1. The followini true signal (s) due to o Reactor transient are i ntl i c a ted ny a l a r rn o r i ncl i c a t i on and the required full scram does not insert con t r ol rods i

.ns indicated on the full core display, rod posi tion printout on the c oinpu te r , or four rod display:

. a. Reactor Low Water Level 3 (t2.5"). l 1

0. High Orywell Pressure L.69 psig.

l c. Sc ram Di scharele Vo lu me H i gh Water Level (Scr am Alarm).

d. Main Steam Line High Radi3 tion (lster0).

e. Tur9ine Stop Valve Closure.

t. Control Valve Closure (Turoine Generator Load Reject).

g. Hiyh Power Thermal Trip (f Iow biased APRM).

n. High iteutron Flux ( L 20 5, in RU'4, 15% in Startuo).

i. MSIV Closure (less th in 90% open in Run).

j. High deactor Pressure aoove 194 3 p s i g .

I 2. Reactor pressure and/or neutron flux indication increases abruptly, a n't may go of f-sc ale on recorders an<l meters. Tnis is tne key i nd i ca t i ori to recognizing an ATWS event.

3. Satety-Peliet Valvus miy Litt.

4. Other Indications:

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, a. Increising drywell Pressure and Temuerature.

l b. Increasino Suppression Pool T e mpe r a t.u r e .

c. PossiOlu incruo'.e i tt conteinment r a rl i .i t i on levols.

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d. Possiule High Stack snd s Off-Gas release ratos.

e. R r'C i FC u l d t i of) P tl440 s trip dith jet pum0 anti core i l o vd :.10C r U d s i n() e B. eUI2"Allt_6CIl021

1. ucctor H eci rculation Du nos trip orf at 1135 asig  !

Reactor Preissure or Keoctor iater Level 2 (->0"). .  ;

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2. The fpilowing auto'natic ictions are possible:

,s . HPC$ Auto Initiation.

O. RLIC Auto Initiation.

c. LPCS Auto Initiation.

cl . LPCI Auto In i t i,iti on.

o. Ar,5 Auto Ini t i a t i on.

l f. Division I, II, III Diesel Generators Auto i

Start.

I

q. ?rimary Contannu.ent and Reactor Vessel Isolition.

n. Stanony Gas Tre.itment System Auto Start ona Ruactor Building ventil.3 tion I s o l,,i t i on .

i. Off Gas System Isolation.

C. IMMEDIATb OPERATUe4 ACT10M5

1. MANUAll.Y SCRAM tne RedCtor ds follows:

a. ARM and OdPRESS Manual Scram .Pushbuttons.

l b. PLACE Reactor Moda Switch to Shutdown.

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c. CHECK that d eactor P o ,. st r is decre.jsing with no r m,s l neutron a ec. .s y and .s i l roos are tully instrtod.

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2. If the Reector Scrams, REFER to LGP 3-2, Heactor Scram. It the R06ctor Scrdms, DU 10T CONTIt40E tnis Proceaurv.-

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- 3. VERIFY the following automatic actions:

a. Reactor Recirculation P urrp s trio.

O. Safety-Relief valves open to mai ntai n Reac tor pressure nelow 1250 psig.

4. CHECK w h e t n r. r the Backup Scram V.)Ivei cause the Reactor to sc r ain. If a s c r a.n still is not indicited:

a. ' START tne Standay Liquia Control System, usin) both pumps to achjeve a flow of 86 'jpm w i thi n ONE MINUTE of the start of the event.

o. VERIF* isolation of the Reactor Water Cleinup System.

S. MAINTAIN Feedaater fIow to the Reactor vessel, if possible, to maint:iin normal Reactor level as tollows:

a. OPERATE Turbine Oriven Reactor Feed Pumps it

. the MSIV's are JPEN.

D. CPER ATE the Motor Dr i ven Reactor Feed Pump it the MSIV's are CLdSED.

c. OP ER A f F. tne Reettor Level Control System per LOP-RL-01 to 'nai ntai n normal Reactor level.

6. VERIFY tne following if P.edc tor Water Level 2 (-50")

is exceeded:

a. HPCS Auto Start Sequence.

o. RCIC Auto Start Sequence.

7. VERIFY the tolIowing it 1 69 psiq in Urywel1 i5 exceeded or Reactor level decreases to Level 1 (-

L30"):

a. HPCS Auto Start Sequence.

D. LPCS Auto Start Sequence.

c. LPCI auto Start Soyuente.

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d. Diesel Auto Start Sequence.

8. STARTUP Suppression Pool Cooling using both RH4 Hedt )

Exchangers within 10 minutes of the start of tne .

event as follows:  !

d. START HHR Service Water in accordance with LOP-

,, RH-05, RHR Service Water Operation.

D. PLACE A and B RHR Systems in the Suppression

. Pool Cooling 9ade and REFCR to LOP-RH-L3, Suporession Pool Cooling Jperation.

9. If Reactor level could not be controlled normal l y with Feedwater and HPCS or RCIC were initiated, when Reactor Level approaches Level 8 (55"):

a. CLOSE HPCS Injection valve.

b. CONTROL Reactor Water Level aoove Level 2 (-

50") manually, usinI RCIC.

10. VERIFY AUTO START of Stanony Gas Treatment System

if aoplicdDlu limits were reacned as follows:

a. Reactor level decreased to Level 2 (-50").

t' O. High Urywell pressure (1.09 psig).

c. High Reactor Building Ventilation Exhaust Radiation.

d. Hign Fuel Pool Ventilation Exhaust R ad i a ti on .

it. V ER IF Y Primary Containment Group Isolations occur if any applicaole limits are exceeded.

12. CHECK whetner the ' lain Condenser is available.

Control Reactor pressure with dypass valves if tne

• 4ain Condenser is available and Stack Gas activity l levels are normal.

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1. VERIFY the following indications:

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D. Reactor pressure is (Nlow 1076 usig.

c. Reactor level is above Level 2 (-50"). C'Jr4 T R d L R ea c t t> r level witn (CIC, HPCS, or Feedwater flow, it possible.

'- d. Core flow decreases to riutural circulation level, consistant wien operating map.

e. If containment pressure redches or e xc ee ds 30 osiy, USE wetwell s p r.s y to Cor4 TROL containment pressure.

t. Both S t.in d o y Liquin Control Pumas are running and St-inany Liquio Control Solution Tanx level is decreasiny. l CAUT104 l

4 1. De-energizing PPS ousses will result in a loss

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of neutron monitorinq instrumentation.

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, 2. The following att'impts to scram tne Reactor

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are to De porformed concurrently if manuoner i ,

is sutticient.

l 2. C HS C 4, Control Rod Position Indication. It the control rails have not fully inserted, P ROC t: ED to j scram the Reactor in tne foi lowing order:

a. DE-ENERGIZE RPS Subchannel Logic Dy openinq breakers from control room panels 1H13-P609 I and Iril 3-P 611 (2H13-P609 dna 2H13-P611).

o. TRIP RPS Scram Logic Breakers CB-2A an r1 CU-2B at the RPS Oistriuution Bus in the Auxiiinry Electric Room.

c. OPEN the followitrl RPS Power Supply breakers for 2 minutos 10cally at the RP5 Power Supply E>u s e s an d MG Set control uariel s asia trien R ECLtJSti:

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1) R P S '1C S e t "A" output breaker.

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2) RPS HG Set "B" output Dreaxer.  ;

3) CB-1, RPS Alternate Power Supply bre1ker from MCC 1328-1.

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d. INDIVIDUALLY SCRA:4 Con t r ol Rods at Local Hydraulic Control Units (HCU's) Or placing

,, Brancn Junction Module Switches to the Scram-Test oosition.

e. ISOLATE air from the scram air system by closiny I 1C11-F095 (2C22-F095); Scram Air Supply Valve.

f. MANUALLY INSERT Control Rods from Control Room Panel LH13-P603 (2Hl3-P603) using tne Reactor Manual Control System.

1

3. CHCCK Stacx Gas Release 4 ate and Off-Gas Release Rate. INITIATE GSEP if necessary.

4. AFTER the Reactor i s shutdown to the level where j the only source of power is decay heat, PROCEEU to a

stabilize Plant Condition in Hi]T SHUTOOWN as follows:

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Do not shutdown 5BLC injection once it has been

, started until the SBLC Solution Tank is veritivo to

, ce empty.

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a. SAMPLE Reactor Coolant frequently to VERIFY j Boron concentration is above the l evel determined to maintain the plant snutdown (acove 750 pum l witn all rods out).

n. PERFORM either step D.4.b.1 or D.9.o.2 as l follows:

l L) MAINTAIN Reactor at 1000 to 1050 psig uy

operatina a Relief Valve and removing neot from the containment using Suparossion Pool Coolinu.

2) MAINTAIN Peactor at 1000 to 1090 psig as Pollows:

a) VERIFY that Boron concentration in the Wedctor will De sutticient to maintain the Reactor shutdown ottor

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.lc c oun t i n t] for s no r mes ) Startup of tne Steim Condensing 't o.l e o f RHR.

b) S T A -( T U P tne Stesm C atul+f os i n.J Mode ut R et R in accordanco d i t n L O P-R H-0'# .

Ste.im condensins) 5tartuu and Uperation.

5. When t he P '.*ac to r is to be shutdown to COLD SHUTUUWN, PRUCLED u s i nt) the f ol l ow i n:J Corts i de r a ti on s *

a. Sufficient nmiative reactivity nas been inserted to the Re.sctor to account for the posit.ive reactivity effects temper a ture and oilution.

201E Carryover snould not significantly attect Reactor Boron concentration,

n. It the alant is not containinatud and the xerictor is not isolated. a normal shutdown and couldowri in accordance with LGP 2-l can oe perrormoa.

c. CAUTION it'uSt be taken that the uricorated notor in the dHR Shutdoun Coolinij lin.ts does not tersporar i 1 y di l u te the Boron in the core to allow criticality us follows:

,, 1) ESTABLISH an excess Boron ConcentrJtion to accomodate for tric e t t ec t of dHR qilution (30*. excess is required above ttie 75d-1000 I

DPM concentration).

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2) STARTUP the Reactor decirculation Pumps in SLOW speed in order to nomoqenize vessel doron concentration. If tne Primary j Containment is isolated, tne isolation signal must ou reset in order to supply RBCCW to the Pecirc. Pumus.

,3 ) START 4HQ Shutdown Cooling ilow to tne Reactor Vessol gradually Dy thr o t t l i tig OPEN the Snutclown Coolin i Injection valve l (The RHR Pumu tii n i mu n F I ow V-ilve must ce overridoen in the closed pos i t i ori to

.; r e v e n t tne loss of bo r ,s t e d water).

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d. Do not exceed a 100 F/hr couldown rate (TS).

e. When flooding the Reactor Vessel up to the steim oome, use a source of water borated to the same concentration as the water in the Reactor to urevent Redctor doron concentr.ition dilution. The SBLC Solution Tank can De used.

However, if using the 56LC Pu nps, Reoctor flooding will require one to two days. An alterncite pump cdn ce used.

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f. Concentration levels of Baron in the deactor Vessel will be 750-1000 pom. The mi ni mum o

solubili ty of Boron in water at 32 F is greater than 5000 ppm.

g. It a fuel element tailure is suspecte<s, refer

, to LGA-16, Fuel Elenent Failure.

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] An ATWS (Anticipated Transient without scram) is extremely

, unlikely but will require prompt oporjtor action to

. mitigate the consequences. Operator concerns are as

follows- 1) VERIFY that Recirculation pumps trip. 2) 3 Shutdown of Reactor. 3) L i .n i t Reactor oeak pressura 4)

Maintain the core covered. 5) Limit the temperature of the Suporession Chamber, and 6) Long-term couldown.

I The operator must attempt to scram the Qeactor with the

! most readily available means. Upon recogniz.ing that tne Reactor does not scram, tne operator snauld 1*jl((ATS SIAggj[ ({gg1Q CQg[ fig ( (h](C[ g(lHig [Mg j[gg((1 QF pfg gV,ggi to m i n i m i z e R eac to r power producti ori, wnich would heat-up the containment. HPCS or RCIC Operation is necessery to maintain the core covered if feed riow is

! stoppad. and should be initiated i f Level ?. (-50 inches) j is approoched. Sucoression Pool Cooling using two RHR Heat Exchanocrs <.,ust ne irii t i a ted to ensure tnat Suppression

, Chamber temperature limits are not exceeded.

4 Subsequentiy, the operator must insert enoulh neg sti ve reactivity into the Reactor ~ so that an uncontrolled restart will not occur. Thus, a cooldown must not ne

'nitiated until Control Rods are inserted or Boron concentration is determined sa ti s f ac tor y. The consequences of this accident to the containment end environment must be evaluoted. GSEP should .3 e initiated if necessary.

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Inna0 I - Assuming 1007 Reactor power and a two minute t i me <1e l ,iy to tne start of Boron injection, Suppression Poul temperature will peak at 177 F after 28 mi nutes wi th the M51V's c l osed or 105 F a f ter two mintites with Bypass Valve capabi1ity. Conteinment pressure wilI pe.ik at 3.5 psig with t'SIV closure or . *1 psi g wi th dyoess Valve capability. Hot shutcown should be achieved within 18 minotes of Boron injection. However, once Soron injection is stsrted, it tiiu s t be run to completion: 00 NOT SHUTOOWN 58LC UNTIL POSITIVE VERIFICATI01 THAT THE S3LC SOLUTION TANK IS EMPTY.

It must ce noted that E & l t,g i d Q E i j s S g a l 1 C_ E i d ' [ I*,! d Gy1 69 $U3915SL Id6211E21 EE2211El id61 EiiE12E BEELSEUkall2U EMtti BEtelu UEEdillus 19 HEE 1211E 59102 'd11199 Tne release limits of 10 CFW 100 apply to tne ATWS event.

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