ML19340C417
| ML19340C417 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/07/1980 |
| From: | WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP., WESTINGHOUSE ELECTRIC CORP. |
| To: | |
| Shared Package | |
| ML19260G402 | List: |
| References | |
| NUDOCS 8011170237 | |
| Download: ML19340C417 (17) | |
Text
{{#Wiki_filter:' WlESTINGiOUSE 3ROPEARy CLASS lll O INADVERTENT BORON DILUTION HISTORY: REGULATORY GUIDE 1.70 REV.1 (PRE-9/75) REQUIRED INVESTIGATION OF ONLY OPERATING MODES 1, 2 AND 6 (REACTOR CRITICAL AND REFUELING). ISSUANCE OF REG. GUIDE 1.70 REV. 2 REQUIRED THE INVESTIGATION OF ALL MODES OF OPERATION - POWER OPERATION , STARTUP HOT STANDBY s HOT SHUTDOWN COLD SHUTDOWN REFUELING
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l ES~!NGJOUSE PRO?RlETARY Cl. ASS Ill TABLE 1.1 OPERATIONAL MODES REACTIVITY % RATED AVERAGE COOLANT CONDITION, K THERMAL POWER" TEMPERATURE MODE ff
> 0.99 > 5% ),350*F
- 1. POWER OPERATION
- 2. STARTUP > 0.99 1 5% ~ > 350*F
- 3. HOT STANDBY < 0.99 0 > 350*F
- 4. HOT SHUTDOWN < 0.99 0 350*F > T avg
> 200*F
- 5. COLDSHUTbOWN < 0.99 0 1 200*F
- 6. REFUELING ** 1 0.95 0 1 140*F
^ Excluding decay heat. ,
Reactor vessel head unbolted or removed and fuel in the vessel.
#2 l
l l l t - w 007 1 1975
WEST NGHOUSE ?ROPR'ETARy CLASS Lil REQUIREMENTS OF EVALUATION: PRIOR TO R.G. 1.70 REV. 2 - TIME FOR OPERATOR RESPONSE FROM INITIATION OF DILUTION EVENT: MODE 1 15 MINUTES 2 *15 MINUTES 6 30 MINUTES POST R.G.1.70 REV. 2 - TIME FOR OPERATOR RESPONSE FROM INDICATION / ALARM THAT DILUTION EVENT IS IN PR0' , MODE 1 15 MINUTES 2 15 MINUTES 3 15 MINUTES 4 15 MINUTES
~ ;
5 15 MINUTES 6 30 MINUTES ,. 7 l' 1
. MS~TG:10USi MOPRiTARY C'_ ASS Lll l
i i 1 POTENTIAL CONCERNS ARE:
- 1. WHEN ON RHR - MODES 4, 5, AND
- 2. WHEN HAVE RCP FORCED FLOW BUT REACTOR IS SUBCRITICAL O
i 4
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WES~TGTOUSE ?R0PEARy CLASS III J
~
V NOT CONCERNED WHEN:
- 1. IN MODE 6 - REFUELING DUE TO LOCK OUT OF FLOWPATHS
- 2. REACTOR IS CRITICAL
- 3. ' REACTOR IS INTENTIONALLY APPROACHING CRITICALITY AND UNDER
- , CLOSE OPERATOR CONTROL FOR 2 AND 3 NOT CONCERNED BECAUSE:
i A. RODS WITHDRAWN - HAVE A MEANS FOR QUICK SHUTDOWN B. MANY ALARMS FOR OPERATOR NOTIFICATION WITH SUFFICIENT TIME TO RESPOND , C. CONDITIONSBOUNDEDBYOTHERANALhSES - W i
WiS~KGH0JSE PRO?R'ETARY CLASS L' CONCERNS ARE POTENTIALLY WORSE WHEN ON RHR BECAUSE:
- 1. , SMALLER ACTIVE RCS VOLUME (* 2500-5000 FT3 )
- 2. RHR FLOW RATES SMALL (3500-4000 GPM)
- 3. HIGHER INJECTION RATES FROM CENTRIFUGAL CHARGING PUMPS DUE TO' LOW RCS PRESSURE (* 300-500 GPM @ 15 PSIA) i 4. SMALLER SHUTDOWN MARGIN - 1% AK/K AT 200*F e
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WiS~lNGH0JSE M0PRUARY C_' ASS Ill 4 1 i BORON DILUTION EVENT ADDRESSED BY: MODES 1, 2 - BOUNDING ANALYSES IS UNCONTROLIED ROD WITHDRAWAL i MODE 6 - ADMINISTRATIVE CONTROL OF POSSIBLE DILUTION FLOWPATHS BY LOCKING VALVIS CLOSED IN FLOWPATHS MODES 3, 4, 5 - DETECTION OF DOUBLING 0F SOURCE RANGE NEUTRON , FLUX; RESTRICTIONS ON MAKE-UP FLOW RATES, AND , i INCREASES IN SHUTDOWN MARGIN AS REQUIRED i l THUS FOR A SUBCRITICAL SYSTEM, THE BORON DILUTION DETECTION / MITIGATION , , SYSTEM PREVENTS INADVERTENT CRITICALITY l 1 l i e
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W87 \GN0USE PRO 3RlHARy C.. ASS lli I APPROACH METHODOLOGY 4
- 1. DETERMINED RANGE OF CRITICAL CB TO BE COVERED
- 2. VERIFIED EXPECTED SOURCE RANGE COUNT RATES AFTER REACTOR TRIPS
' 3. USED DOUBLING 0F SOURCE RANGE NEUTRON FLUX TO DETECT TRANSIENT AS EARLY AS POSSIBLE
- 4. DETERMINED DILUTION RATE / SHUTDOWN MARGIN COMBINATIONS THAT SATISFY TIME CRITERIA ,
S. DETERMINED APPROPRIATE OPERATOR / SYSTEM RESPONSE
- 6. DEVISED MEANS OF DETECTING D0'sBLING OF SOURCE RANGE NEUTRON FLUX e
f 1
WES~lNGHOUSE 3ROPRIE"AiY C_ ASS I PERFORMED SEVERAL EVALUATIONS AS PART OF PROCESS: ,
- 1. LOOKED AT DATA ON:
A) MAKE-UP PUMP CAPABILITY B) CHARGING PUMP CAPABILITY C) NUMBER OF PUMPS OPERABLE WHEN ON RHR D) SHUTDOWN MARGINS E) [ ] +c
- 2. DETERMINED THAT POTENTIAL EXISTS FOR INJECTION OF UP TO 400-500 GPM 0F CLEAN WATER FROM PFWS TO THE CORE
+c
- 3. DETERMINED THAT[ ]PREDICTSAMORECONSERVATIVE ,
+c c JIME FOR FLUX. DOUBLING, I.E. 3 LATER IN TRANSIENT, THAN[ ,
/
4
WEST NGNOUSE PROPRlETARy CLASS 'll USING[ ] APPROACH TO CRITICALITY:
+c
),
- 2. [ ]
, 3. VERIFIED FROM PLOTS THAT ALARM ON FLUX DOUBLING COULD MEET TIME CRITERIA. CRITICAL PARAMETERS ARE BORON WORTH AND SHUTDOWN MARGIN.
1
- 4. DETERMINED THAT BORON WORTH OF[ ]PCM/ PPM IS USED CONSERVATIVE.
TO DEFINE SHUTDOWN MARGINS.
- 5. ASSUMING DIFFERENT SHUTDOWN MARGINS, TIME FROM DOUBLING OF FLUX TO CRITICALITY WAS DETERMINED AND COMPARED TO NRC CRITERIA FOR EACH DILUTION RATE.
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.- -m - - - _ a . m WE.STi\GLOUSE 'RO?RlUARy CLASS 'l AS A RESULT OF COMPARISONS, THE FOLLOWING LIMITS ARE NECESSARY:
MODES 3, 4 - SHUTDOWN , MARGIN 1 1 6% aK/K DILUTION RATE 1 20.0 PPM / MIN MODE 5 - SHUTDOWN MARGIN 1 1 0% AK/K DILUTION RATE 1 10.0 PPM / MIN THE DILUTION RATES RESULT IN INITIATING SYSTEM RESPONSE S 2-3 MINUTES PRIOR TO CRITICALITY. THIS IS SUFFICIENT TIME FOR VALVE ACTUATION TO CLOSE OFF THE CVCS AND TAKE SUCTION FROM THE RWST, AND PURGE THE LINES OF CLEAN WATER TO THE RCS COLD LEG. l l 5 l
W.ESTl\GFOUSE ?ROPR!E7Agy CLASS m i l DOUBLING OF FLUX DETECTED BY: i
- 1. SOURCE RANGE NEUTRON FLUK MONITORED WITH MICROF?0CESSOR
- 2. [ ] +c
,- +C 3.
+c 4.,
- 5. UPON DETERMINING FLUX HAS DOUBLED - ALARM SOUNDED, VALVE MOVEMENT INITIATED c'
i r . _ , . , - - - - . . .- - - - - - , . ---y.- ,m , n._
WES"l\GF00SE ?ROPRLETARY CLASS lll ADVANTAGES OF USE OF MICROPROCESSOR:
- 1. ALLOWSDETECTIONOFALONGTIMECONSTANTEVENT,{ANDETECTPOWER ESCALATIONWITHREACTORPERIODASLONGAS[ ] SECONDS
- 2. ELIMINATES DIFFICULTIES ASSOCIATED WITH DETECTING A SMALL SLOPE CHANGE OVER LONG PERIODS OF TIME IN A LOG SIGNAL
- 3. NOT AS SUSCEPTIBLE TO NOISE AND LOW COUNT RATE STATISTICS e *
[ l l t i
. WES7GHOUSE ?ROPi E"ARY CLASS i RESULTS:
- 1. USE MICROPROCESSOR TO DETECT DOUBLING 0F SOURCE RANGE NEUTRON FLUX AND TRIGGER ALARM / SYSTEM RESPONSE e 2. COMANCHE PEAK WILL AUTOMATICALLY OPEN RWST ISOLATION VALVES AND CLOSE VCT/CVCS ISOLATION VALVES
- 3. REACTOR MAKEUP WATER FLOW RATES INTO CVCS RESTRICTED AS NECESSARY TO ALLOW TIME FOR DETECTION / RESPONSE
~
9 C I e
.' WESTGGHOUSE PRQPRIETMy CLASS
\ l 8 IMPACT ON PLANT: i i
- A. HARDWARE CHANGES
) l
- 1. ADDITION OF FLUX 00U3 LING CIRCUIT TO SOURCE RANGE
- 2. MODIFICATION OF PROTECTION SYSTEM TO INITIATE VALVE MOVEMENT
- 3. ADDITION OF ALARM
- 4. RESTRICTION OF RMWS TO CVCS BY ORIFICES OR THROTTLE VALVES B. OTHER CHANGES
- 1. RESTRICTION ON RMWS FLOW CAN INCREASE DILUTION TIMES FOR PLANNED CRITICALITY
- 2. ADDITIONAL REQUIREMENTS ON SOURCE RANGE OPERABILITY IN MODES 3, 4, AND 5 ,-
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