ML20141D893

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Proposed Tech Specs 3.1/4.1 Removing Run Mode IRM High Flux/ Inoperative W/Associated APRM Downscale Scram Trip Function (IRM Run Mode Scram)
ML20141D893
Person / Time
Site: Millstone Dominion icon.png
Issue date: 05/15/1997
From:
NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20141D880 List:
References
NUDOCS 9705200231
Download: ML20141D893 (13)
v • d • e


Text

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  • JAN 2 9.1987 l

TA8tt 3.1.1 ..

REACTOR PROTECTION SYSTEM (5CRM) INSTRUMENTATION REQUIREMENTS 7

01nteseihm6er j cf Operable Medes in which Function I:st. Channels Trip Fenetton Trly level Setting Most to Operable Action

  • per felp (1) REFUEL / STARTUP/ MOT Systee $NUTOUWN (8.11) STANotY ' Il0N I Mode Swttelt in SitR00Wil I t 's A i 1 Ileneel Scree u X -t A 1EM:

. . 3 Migh Flen $120/125 et full scale R R M A 3 Insporettve A. Mt Voltage <te weit DC I X  :: "1C) .A i S. IllN Module Unplugged  ;

C. Selector Swltch not in ,

Operate Positten apish

  • r 1 2 Flow 91esed Nigh Flen See Section 2.1.24 --R-- -t- X A er 9
  • 2 Reduced Nigh Fles See Section 2.1.24 X X + Ah '

2 Insperable A. > 5OE LPM Inputs ** R X X A er 9 l 3. Circett Seerd Demoved C. Selector Switch not in t Operate Positten 2 Nielt Reacter Pressere $1085 pste N y W A.

t - Nieh Deveell Pressere $2 pste X (9)

X (7) I (7) A

! Reacter Lev. Water _ Level 21.0 Inch *** I I X A.

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2 Scres 90scharge vel. s2s inches ebewesthe center- X (2) X X A Nigh Level line of the 1 ewer end cop  :

Le 50tv pipe weld  !

3/4 1-3 Amendment No. 1 .

Mllistene 'init 1 otn l

9705200231 970515 PDR ADOCK 05000245 -

P PDR

-_ __m+ _ g +_- ie + -yw --w.-% -e -we --

  • m 9- =-w e-- i-ee- r ---e ---+we- -=9%-9 wi 9?M* - - A +Hm- e----- _ _ - _ _ _ _ -

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TABLE 3.1.1(Continued)

Reactor Protection System (Scram / Instrumentation Requirements 9/29/93 l

tcs: g,7 y,y.D -

5. Ms-are Li ves W Ja . c4e switch-4s-p1&cM is . _... The A tector fer ;; d ;;. 41e I N Jully * :;. ted etil it.e assectated-AG ch;.. .;1 is ;;_. Als er.4-indic.tii.9 et le;st 3/125 511 stele . .
6. ' The design pemits closure of any one valve without a scram being iritiated.  !
7. May be bypassed when necessary by closing the manual instrument isolation valve for scram of PS-1621 A l through D during purging for containment inerting or deinerting.
8. When the reactor is subcritical and the reactor water temperature is less than 212*F, only the following trip functions need to be operable:

t

a. Mode Switch in SHUTDOWN
b. Manual Scram '
c. High Flux IRM  ;

- d. Scram Discharge Volume High Level

e. APRM Reduced High Flux '
9. Not required to be operable when primary containment integrity is not required. ,

Nor' uit b -

10. 4Mth the ::f; swild in-RUN Msith en 1.:;;att : trip T_...i.ivn also reqstres an as>=,iuted APRM j l' "f;r. scale alarm "

' 11. Trip funct'ons are not required to be operable if all control rods are fully . inserted, and either.

electriedly or hydraulically disarmed in accordance with Specification 4.1.D.

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2 Millstone Unit 1 3/41-5 AmendmentNo.J.JJ,49,JJg  !

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' TABLE 4.1.2 sm. 4, m3?

SCRAM INSTRtMENTATION CALIBRATION MINIMUM CALIBRATION FREQUENCIES FOR REACTOR PROTECTION'INSTRtMENT CHANNELS .

Calibration Minimum Calibration

  • Instrument Channel Group (1) Method Frecuency (2)

APRM Output Signal (4) 8. Heat Balance Once every 7 days .

APRM Flow Blas Trip B Standard Current Source Once every 3 months APRM Reduced High Flux Trip (5) B Standard Current Source Once every 3 months IRM6d B StandarbCurrentSource Refueling High Reactor Pressure A Pressure Standard Every 3 months High Drywell Pressure A Pressure Standard Every 3 months -

Low Reactor Water A Delta Pressure Standard Every 3 months -

Condenser low Vacuum A Vacuum Pump Every refueling Generator Load Rejection A Pressure Standard Every refueling High Water Level in Scram Discharge A Water Level. Every 3 months Notes: 1. A description of the three groups is included in the bases of this Specification.

2. Calibration tests are not required when the systems are not required to be operable or are tripped. If tests are missed, they shall be performed prior to returning the systems to an operable status.
3. Maximum calibration frequency required is once per week.
4. The heat balance method serves the calibration of the normal APRM high flux trip and the reduced APRM high flux trip. '
5. N 2.c.M ., t st.n c u,, ts 3k.il h. 4 + --,:,eA 4,,

ceap avd,3 wh Sw +ve af w w h i,3 N mTwhT mony Md. -s4 A m ud m, a .,,.t3 as.ti t...k w ,.,J * - t,, a- % m t , o,sik4 MJ~%

p a + p < w -, A -.n
, W p<.d.a r A qs.

Millstone Unit 1 3/4 1-8 Amendment No.64 44+4 tc(

3.1 REACTOR PROTECTION SYSTEM BASES.

I:

The reactor protection system automatically initiates a reactor scram to:

1. preserve the integrity of the fuel cladding;
2. preserve the integrity of the primary system barrier;' and
3. minimize the energy which must be absorbed, and prevent criticality following a loss of coolant accident.

These specifications provide the limiting conditions for operation necessary to preserve the ability of the system to tolerate single failures and still perform its intended function even during perilodsWhen when instrument necessary, one channels may be out of service because of maintenance.

channel may be made inoperable for brief intervals to conduct required functional tests and calibrations.

The reactor protection system is of the dual channel type. Ref.

Section 7.2 of the UFSAR. The system is made up of two independentEach logic subchannel channels, each having two subchannels of tripping devices.

has an input from at least one independent sensor monitoring each of the critical parameters.

The outputs of the subchannels are combined in a 1 out of 2 logic; i.e.,

an input signal on either one or both of the subchannels will cause a trip system trip. The outputs of the trip systems are arranged so that a trip on  ;

both channels is required to produce a reactar st.nm.

This system meets the requirements of the proposed IEEE Standard for Nuclear Power Plant Protection Systems issued September 13, 1966. The system has a reliability greater than that of a 2 out of 3 system and somewhat less than that of a 1 out of 2 system.

With the exception of the Average Power Range Monitor (APRM), Intermediate Range Monitor (IRM) channels, Main Steam Isolation Valve Closure, and Turbine Stop Valve Closure, each subchannel has one instrument channel. When the i

l '

minimum condition for operation on the number of operable instrument channels per untripped protection logic channel is met or if it cannot be met and the affected protection trip system is placed in a tripped condition, the effectiveness of the protection system is preserved; i.e., the system can tolerate a single failure and still perform its intended function of scramming the reactor. Three APRM instrument channels are provided for each protection trip system.

APRMs #1 and #3 operate contacts in a logic subchannel and APRMs #2 and

  1. 3 operate contacts in the other logic subchannel.

-a 5 .J e to y%v JM # 6 ~14 +

APRMs-#+r-d5--and-M are arranged similarly in the other protection trip system. Each protection trip system has one more APRM than is necessary to meet the minimum number required per channel. This allows the bypassing of one APRM per protection trip system for maintenance, testing or calibration.

I' B 3/4 1-2 Amendment No gstoneUnit1 l

e 4,1 REACTOR PROTECTION SYSTEM 007 3y g BASES Group (C) devices are active only during a given portion of the operational cycle. For example, the IRM is active during startup and inactive during Thus, the only test that is meaningful is the one full-power operation.

performed just prior to shutdown or startup; i.e. , the tests that areWhile included in Group '

performed just prior to use of the instrument. '

the Condenser Low Vacuum trip is treated differently. This is because l

the condenser low vacuum trip sensor can only be tested during shutdown.

The primary function of this trip is to protect the turbine and condenser, i although it is connected into the reactor protection system; thus testing the sensor at each refueling outage is adequate. l Calibration frequency of the instrument channels is divided into two groups. '

These are as follows:

~

a. Passive type indicating devices that can be compared with like units .

on a continuous basis.

b. Vacuum tube or semiconductor devices and detectors that drift or lose sensitivity.

Experience with passive type instruments in generating stations and For substations indicates that the specified calibrations are adequate.

those devices which employ amplifiers, etc., drift specifications call for drif t to be less than 0.4%/ month; i.e. , in the period of a month a drift For the APRM of 0.4% would occur thus providing for adequate margin.

system, drift of electronic apparatus.is not the only consideration in ]

determining a calibration frequency. Change in power distribution and loss of chamber sensitivity dictate a calibration every seven days.

Calibration on this freque.ncy assures plant operation at or below thermal limits.

'3hl3 F RT A B. The peak heat flux shall be checked once per day to determine if theThis w APRM scram requires adjustment.

the LPRM readings. Only a small number of control rods are moved daily, l thus the peaking factors are not expected to change significantly and a  ;

daily check of the peak heat flux is adequate. )

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Millstone Unit 1 B 3/4 1-9

l 4

INSERT A [4.1 REACTOR PROTECTION BASES PAGE B3/4 1-9]

i SRM/IRM/APRM overlap Surveillances are established to ensure ,

that no gaps in neutron flux indication exist from subcritical to power operation for monitoring core {

reactivity status. j The overlap between SMis and IRMs is required to be i demonstrated to ensure that reactor power will not- be increased into a neutron flux region without adequate  :

indication. This is required prior to withdrawing SRMs from i the fully inserted position since indication is being transitioned from the SRMs to the IRMs. 4 The overlap between IRM's and APRMs is of concern when l reducing power into the IRM range. On power increases, the system design will prevent further increases (by initiating  ;

a rod block) if adequate overlap is not maintained. Overlap between IRMs and APRMs exists when sufficient IRMs and APRMs concurrently have onscale readings such that the transition  ;

between the RUN and STARTUP/ HOT STANDBY Modes can be made i without either APRM downscale rod block, or IRM upscale rod ]

block, overlap between SRMs and IRMs similarly exists when, ,

prior to withdrawing the SRMs from the fully inserted )

~

position, IRMs are above mid-scale on range 1 before SRMs l have reached the upscale rod block. i As noted,IRM/APRM overlap is n.11y required to be met during entry into STARTUP/ HOT STANDBY Mode from the Run Mode. That 4

is, after the overlap requirement has been met and indication has transitioned to the IRMs, maintaining overlap in not required (APRMs may be reading downscale once in the STARTUP/ HOT STANDBY Mode).

If overlap for a group of channels is not demonstrated )

(e.g., IRM/APRM overlap), the reason for the failure of the l Surveillance should be determined and the appropriate l channelle) declared inoperable. Only those appropriate '

channela that are required in the current condition should .

be declared inoperable.

l

- - .. ~ .- - - .- - -. -

o, Docket No. 50-245 >

B16407 B

4 Attachment 4 Millstone Nuclear Power Station, Unit No.1 Proposed Technical Specification Revision Neutron Monitoring Retyped Technical Specifications and Bases W

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May 1997 l

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"1 TABLE 3.1.1 REACTOR PROTECTION SYSTEM (SCRAM) INSTRUMENTATION REQUIREMENTS e

minimas thaber of aparebte Icedes in did Fametten

.- Inst. Onesenets Trip Fametion Trip Lowel Settire mast to Etaorable Actlan*

per Trip (1) system RERdEL/ STARTW/WUF Semitteal (8,11) STAABST Mai 1 Isode switch in suutDonal X X X A 1 leanual scrum X X X A IRM:

3 Nigh FLun <120/125 of futt scale X X A 3 Inoperatin A. NI Voltage <80 volt DC X X A

s. Inst Isodule unplugged C. selector switch not in g operate Position AMtet:

7 44 2

2 Flow stased alsh Flun Red xed Nigh Ftun see section 2.1.2A see section 2.1.2A X X X A or B A

2 Inoperable A. >50% LPRIE Iguts" X X X A or 8

5. Circuit Doord Removed C. selector switch not in Operate Position.

2 Wigh teactor Pressure <1085 psig X X X A 2 High crywett Pressure <2 psig I (9) X (7) X (7) A 2 Reactor Low unter Levet >1.0 inch "

  • X X X A 2 scram Discharge Vet. <26 inches above the center-Line X (2) X X A Nigh Level of the lower and cap to SDIV pipe weld t

d s- _.. m

23 TABLE 3.1.1 (Continued) 2 -; Reactor Protection System (Scram) Instrumentation Requirements v.

o E Notes; e

h 5. NOT USED l

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6. The design permits closure of any one valve without a scram being initiated.
7. May be bypassed when necessary by closing the manual instrument isolation valve for scram of PS-1621 A through D during purging for containment inerting or deinerting.

! 8. When the reactor is subcritical and the reactor water temperature is less than 212*F, only the following trip functions need to be operable:

a. Mode Switch in SHUTDOWN
b. Manual Scram
c. High Flux IRM w d. Scram Discharge Volume High Level 1 e. APRM Reduced High Flux
9. Not required to be operable when primary containment integrity is not required.
10. NOT USED l s

y 11. Trip functions are not required to be operable if all control rods are fully inserted, and either

! electrically or hydraulically disarmed in accordance with Specification 4.1.D.

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  • 5 TABLE 4.1.2 i

I-: SCRAM INSTRUMENTATION CALIBRATION

7. MINIMUM CALIBRATION FREQUENCIES FOR REACTOR PROTECTION INSTRUMENT CHANNELS Calibration Minimum Calibration y Instrument Channel Groun (1) Method Freauency (2)

[ APRM Output Signal (4) B Heat Balance Once every 7 days

APRM Flow Bias Trip B Standard Current Source Once every 3 months APRM Reduced High Flux Trip (5) B Standard Current Source Once every 3 months IRM (5) B Standard Current Source Refueling High Reactor Pressure A Pressure Standard Every 3 months I

High Drywell Pressure A Pressure Standard Every 3 months 7 Low Reactor Water A Delta Pressure Standard Every 3 months en

. Condenser Low Vacuum A Vacuus Pump Every refueling Generator Load Rejection A Pressure Standard Every refueling High Water Level in Scram Discharge A Water Level Every 3 months l

Notes: 'l. A description of the three groups is included in the bases of this Specification.

2. Calibration tests are not required when the systems are not required to be operable or are tripped. If tests are missed, they shall be performed prior to returning the systems to an operable status.
3. Maximum calibration frequency required is once per week.
  • . 4. The heat balance method serves the calibration of the normal APRM high flux trip i g and the reduced APRM high flux trip.
5. The IRM and SRM channels shall be determined to overlap during each startup after entering 3 - the STARTUP/ HOT STANDBY MODE and the IRM and APRM channels shall be determined to overlap

- during each controlled shutdown, if not performed within the previous 7 days.

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3.1 REACTOR PROTECTION SYSTEN BASE 1 .

The reactor protection system automatically initiates a reactor scram to:

1. preserve the integrity of the fuel cladding;
2. preserve the integrity of the primary system barrier; and  ;

-i

3. minimize the energy which must be absorbed, and prevent criticality j following a loss of coolant accident.  ;

These specifications provide the limiting conditions for operation l necessary to preserve the ability of the system to tolerate single failures and still perform its intended function even during periods when instrument channels may be out of service because of maintenance. When necessary, one channel may be made inoperable for brief intervals to conduct required functional tests and calibrations.

The reactor protection system is of the dual channel type. Ref.

Section 7.2 of the UFSAR. The system is made up of two independent logic channels, each having two subchannels of tripping devices. Each subchannel has an input from at least one independent sensor monitoring each of the critical parameters.

The outputs of the subchannels are combined in a 1 out of 2 logic; i.e.,

an input signal on either one or both of the subchannels will cause a trip system trip. The outputs of the trip systems are arranged so that a trip on both channels is required to produce a reactor scram.

This system meets the requirements of the proposed IEEE Standard for Nuclear Power Plant Protection Systems issued September 13, 1966. The system has a reliability greater than that of a 2 out of 3 system and somewhat less than that of a 1 out of 2 system.

With the exception of the Average Power Range Monitor (APRM), Intermediate Range Monitor (IRM) channels, Main Steam Isolation Valve Closure, and Turbine Stop Valve Closure, each subchannel has one instrument channel. When the minimum condition for operation on the number of operable instrument channels per untripped protection logic channel is met or if it cannot be met and the affected protection trip system is placed in a tripped condition, the effectiveness of the protection system is preserved; 1.e., the system can tolerate a single failure and still perform its intended function of scramming the reactor. Three APRM instrument channels are provided for each protection trip system.

APRMs #1 and #3 operate contacts in a logic subchannel and APRMs #2 and

  1. 3 operate contacts in the other logic subchannel.

APRMs #5 and #4 together with #6 and #4 are arranged similarly in the other l protection trip system. Each protection trip system has one more APRM than is necessary to meet the minimum number required per channel. This allows the bypassing of one APRM per protection trip system for maintenance, testing or calibration.

MILLSTONE INIIT 1 8 3/4 1-2 Amendment No. 7) em

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4.1 REACTOR PROTECTION SYSTEM BASES  ;

Group (C) devices are active only during a given portion of the operational cycle. For example, the IM is active during startup and l inactive during full-power operation. Thus, the only test that is l

~

meaningful is the one performed just prior to shutdown or startup; i.e., ,

the tests that are performed just prior to use of the instrument. While  ;

included in Group (C), the Condenser Low Vacuum trip is treated differently. This is because the condenser low vacuum trip sensor can only be tested during shutdown. The primary function of this trip is to protect the turbina and condenser, although it is connected into the l reactor protection system; thus testing the sensor at each refueling outage is-adequate.

t- Calibration frequency of the instrument channels is divided into two )'

groups. These are as follows:

a. Passive type indicating devices that can be compared with like units i on a continuous basis.  ;
b. Vacuum tube or semiconductor devices and detectors that drift or

' lose sensitivity.

k Exberiencewithpassivetypeinstrumentsingeneratingstationsand su stations indicates that the specified calibrations are adequate. For  ;

those devices which employ amplifiers, etc., drift specifications call for drift to be less than 0.4%/ month; i.e., in the period of a month a drift  !

of 0.4% would occur thus providing for adequate margin. For the APRM ,

system, drift of electronic apparatus is not the only consideration in i

< determining a calibration frequency. Change in power distribution, and loss of chamber sensitivity dictate a calibration every seven days.  :

Calibration on this frequency assures plant operation at or below thermal l limits.  :

SRM/IRM/APRM overlap surveillances are established to ensure that no gaps i in neutron flux indication exist from subcritical to power operation for t monitoring core reactivity status. l The overlap between SRMs and IRMs is required to be demonstrated to ensure '

, that reactor power will not be increased into a neutron flux region without adequate indication. This is required prior to withdrawing SRMs  !

from the fully inserted position since indication is being transitioned  !

from the SRMs to the IRMs.

The overlap' between IRMs and APRMs is of concern when reducing power into l the IRM range. On power increases, the system design will prevent further l

. increases (by initiating a rod block) if adequate overlap is not  ;

maintained. Overlap between IRMs and APRMs exists when sufficient IRMs  ;

l  !

t MILLSTONE UNIT 1 8 3/4 1-9 Amendment No.  ;

ON7 P

l'.

9 3.1 REACTOR PROTECTION SYSTEM BASES (continued) and APRMs concurrently have onscale readings such that the transition between the RUN and STARTUP/ HOT STANDBY Modes can be made without either APRM downscale rod block, or IRM upscale rod block. Overlap between SRMs and IRMs similarly exists when, prior to withdrawing the SRMs from the fully inserted position, IRMs are above mid-scale on range 1 before SRMs have reached the upscale rod block.

As noted, IRM/APRM overlap is only required to be met during entry into STARTUP/ HOT STANDBY Mode from the Run Mode. That is, after the overlap requirement has been met and indication has transitioned to the IRMs, maintaining overlap is not required (APRMs may be reading downscale once in the STARTUP/ HOT STANDBY Mode).

If overlap for a group of channels is not demonstrated (e.g., IRM/APRM overlap), the reason for the failure of the surveillance should be determined and the appropriate channel (s) declared inoperable. Only those appropriate channels that are required in the current condition should be declared inoperable.

B. The peak heat flux shall be checked once per day to determine if the APRM scram requires adjustment. This will normally be done by checking the LPRM readings. Only a small number of control rods are moved daily, thus the peaking factors are not expected to change significantly and a daily check of the peak heat flux is adequate.

MILLSTONE UNIT 1 B 3/4 1-10 Amendment No.

0267 m v e-v --- r-

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