ML20084M963

Proposed Tech Specs,Changing Calibr/Functional Test Frequency for Specific Instrumentation.Evaluation of Significant Hazards Consideration Encl

ML20084M963
Person / Time
Site:	Quad Cities
Issue date:	05/08/1984
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20084M956	List: ML20084M955 ML20084M963
References
NUDOCS 8405160231
Download: ML20084M963 (10)

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i QUAD-CITIES DPR-29 1

to an out-of-limits input. This type of failure for analog devices is a

! rare occurrence and is detectable by an ope ator who observes that one signal does not track the other three. For purposes of analysis, it is

{ assumed that this rare failure will be detected within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

i The bistable trip circuit which is a part of the Group 2 devices can sustain unsafe failures which are revealed only on test. Therefore, it is necessary to test thes periodically.

A study was conducted of the instrumentation channels included in the Group 2 devices to calculate their ' unsafe' failure rates. The analog devices (sensors and amplifiers) are predicted to have an unsafe failure i rate of less than 20 x 10" failures / hour. The bistable trip circuits are predicted to have an unsafe- failure rate of less than 2 r 10

failures / hour.

Considering the 2-hour monitoring interval for the analog devices as

assumed above and a weekly test interval for the histable trip circuits, the design reliability goal of 0.99999 is attained with suple margin The bistable devices are monitored during plant operation. to record their  !

i failure history and establish a test interval using the curve of Figure 4.1-1 l There are numerous identical bistable devices used throughout the plant instrtsmentation systaa Therefore, significant data on the failure rates for the histable devices should be accumulated rapidly, i

The frequency of calibration of the- APRM flow biasing network has been.

established. at each refueling outage.

, The- flow biasing networic is functionally i

tested at lease once per month and, in addition,. cross calibration checks

] of the flow input to the flow-biasing networic can be made during the J functional test by direct meter reading. (IEEg 279 Standard for Nuclear '

j Fower Plant. Frotection Systeme,. Section 4.9, September 13, 1966). There

are several instruments which. aust be calibrated, and it. will take several days to perfour. the calibratio z. of the entire network i

intile the. calibration

( la being perfossed, resulting s. saro in a. half scraa and flow rodsignal block will be sent to half of the AFRM's,.

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Thus, if thee calibration-1 were perfossed during operation,. finr shaping would noe be possihte

} Based on experience.at other generating stations, drift. of. instrumsat such; j as those in the flow biasing networic is noe significant;. therefore,. to avoid spurious scrams, a. calibration- frequency of eactL refueling ostage is established i

Reactor 1-263-583low unter level instruments 1-163-57A,1-263-573,1-263-58A, and have been modified to be as analog trip systaa The analog trip systes consists of an analog sensor (trarsaitter) and. a. master / slave: trip unit setup which ultimately drives a trip relay. The- frequency of calibration- l and functional testing for instrument loops of the analog trip systen,.

l including reacter lor water level, har been established in Licensing Topical Report NEDO-21617-A (December'1978),

logic, NEDO-11617-A states that each trip unit With. the one-out-of-two-taken-twice l

I be subjected .to.a.

calibration / functional test of one month. Am. adequate calibration / surveillance .

test interval for the transmitteris once. per operating cycle. l i

3.1/4.1-6 8405160231 840508 DRADOCK05000g

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. 1 QURD CITIES DDR-29 Group 3 devices are active only during a given portion of the operational cycle. For example, the IRM is active during startup and inactive during full-power operation. Thus, the only test that is meaningful is the one performed just prior to shutdown or startup, i.e., the tests that are i performed just prior to use of the instrument.

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Calibration frequency of the instrument channel is divided into two groups.

These are as follows: ,

1. passive type indicating devices that can be compared with like units on a continuous basis, and

2. vacuum tube or semiconductor. devices and detectors that drift or lose sensitivity.

Experience with passive type instruments in Commonwealth Edison generating stations and substations indicates that the specified :alibrations are adequate. For those devices which employ amplifiers, ate. drif t specifications call for drif t to be less than 0.4%/ month i.e., in the period of a month a drif t of 0.4% would occur, thus providing for adequate margin.

The sensitivity of LPRM detectors decreases with exposure to neutron flux i at a elow and approximately constant rate. Changes is power distribution and electronic drif t also require compensation. This compensation is acccuplished by calibrating the APRM systen every 7 days insing heat balance j data and by calibrating individual LFRM's at least every 1000 equivalent i full-power hours using TIP traverse data. Calibration o.: this frequency

assures plant operation at or below thermal limits.

A ccuparison of Tables 4.1-1 and 4.1-2 indicates that some instrsseent i channels have not be included in the latter table. These are mode switch j in alustdown, manual scran, high water level in scran dise..arge volme, i main stealine isolation valve closure, turbine control valve fast closure, and turbine stop valve closure. All of the d6 vices or sensors sesociated with these scram functions are simple on-off switches, hence calibration is not applicable, i.e., the switch is either on or off. Based on the above, no calibration is required for these instruasnt channels.

5. The MFLPD shall be checked once per day to detensine if the AFRM se.rm requires adjustment. This may normally be done by checking the LFRM

! readings, TIP traces, or process camputer calculations. Only a small 4

nusber of control rods are moved daily, thus the peaking factors are not espee.ted to change significantly and a daily check of the MFLPD is adequate.

References

1. I. M. Jacobs, " Reliability of Engineered Safety Features as a Function of Testing Frequency", Nuclear Safety, Vol. 9, No. 4, pp. 310-312, July-August 1968.

2. Licensing Topical Report NEDO-21617-A (Deceber 1978).

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)! DPR-29 i

1 TABLE 4.1-1 j SCRAM INSTRUMENTATION AND IDGIC SYSTEMS PUNCTIONAL TESTS i

j MINIMUM FUNCTIONAL TEST FREQUENCIES FOR SAFETT ,

INSTRUMENTATION, IC SYSTEMS, AND C0tfr CIRCUITS )

l Functional Test Minimum Frequencv(4) l 3

Instrument Channel Group 4

Mode switch in shutdown A Place mode switch in Each refueling outage j

4

sh tdown Manual scram A Trip channel and alarm Every 3 months i j

IRM High flux C Trip channel and alam(5) Before each startup

< andweekiguring refueling j

j Inoperative C Trip channel and alarm Before each startup l , and week 1I6i"'188 refueling j!

l APRM High flux B Trip outtet relsys(5) once each week t Inoperative 5 Trip output rejays Once each week j Downscale B Trip output relays Once each week j Eigh flux 15%  ? Trip output reltys Before each startup ,

i andweekiguring re fueling

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! Eigh reactor pressure A Trip channel and alarm (1)

Righ drywell pressure A Trip channel and alam (1)

Reactor low water level (2) , gg) gg) f

.Righ enter level in seem 'A Trip channel and ala m Every 3 monthe

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discharge volume t

4 Turbine condenser low vacum A Trip channel and alarm (1) s Main ste ne high B Trip channel and alarm (5) Once each week i radiation Main stealine isolation valve A Trip channel and slasm (1)

closure

! Turbine control valve fast A Trip chassel and alans ,

(1) closure . .

hubine stop valve. closure A Trip channel and alaan (1) l .

Turbine SEC control fluid law A, Trip channel and alarm (1)

pressare ,

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QUAD-CITIES DPR-29 TABI.E 4.1-1 (Cont'd)

Notes -

1. Initially once par pnth until exposure hours (M as defined on Figure i

4.1-1) are 2.0 X 10 ; thereaf ter. according to Figure 4.1-1 with an interval not less than 1 month nor more than 3 months. The campilation of instruent i failure rate data may include data obtained fra other boiling veter i reactors for which the see design instrument operates in an environment similar to that of Quad-Cities Units 1 and 2.

2. An instrument check shall be perfomed on low reactor water level once per l

day and on high steam 13ne radiation once per shif t.  ;

3. A description of the three groups is included in the bases of this specification.

, 4 Functional tests are not required when the systems are not required to be operable or are tripped. If tests are missed. they shall be perfomed prior to returning the systems to an operable status.

5. This instrumentation is exempted fra the instrument functional test definition (1.0 Definition F)g This instrument functional test will I consist of injecting a simulated electrical signal into the measurement

! channels. ,

6. Frequency need act. exceed weekly.

l 7. A functional test of the logic of each channel is perfomed as indicated.

] This coupled with placing the mode switch in shutdown each refueling i outage constitutes a logic sistem functional test of the scram system.

8. A functional test of the asster and slave trip units is required monthly.

A calibration of the trip unit is to be perfomed concurrent with the j - functional testing.

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QUAD-CITIES

! D PR-29 TABLE 4.1-2 SCRAM INSTRUMENT CALIBRATION i

MINIMUM CALIBRATION FREQUENCIES FOR REACTOR PROTECTION INSTRUMENT CHANNELS Instrument Channel Croup Calibration Standard (5) Minimum Freauency }

High flux IRM C Comparison to APRM af ter Every cogolled heat balance sh'utdown High flux APRM Output signal B Heat balance Once every 7 days Flow bias B Standard pressure and Refueling outage voltage source -

LPRM B(6) Using TIP systen Every 1000 equivalent full power hours j High reactor pressure A Standard pressure source Every 3 months High dryvell pressure A Standard pressure source Every 3 months Reactor low water level B Water level (7)

J Turbine condenser low vacum A Standard vacum source Every 3 months Main stealine high radiation B Refueling outage Appropgte source radiation l Turbine EHC control fluid A Pressure source Every 3 months Iow pressure Notes:

1. A description- of the three groups is included in the bases of this specification, t 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 A current source provides an instruent channel alisment everr 3" months.

4 Maxima calibration frequency need not exceed once per week.

5. Response time is not part of the routine instruent check and calibration but will be checked every refueling outage.

6 Does not provide scram function.

7. Trip units are calibrated monthly concurrently with functional testing.

6 Transmitters are calibrated once per operating cycle.

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QUAD-CITIES DPR-29 l Optimizing each channel independently may not truly optimize the systen considering the overall rules of systen operation. However, true system optimization is a complex problem. The optimums are broad, not sharp, and optimizing the individual channels is generally adequate for the system.

The fonsula given above minfaizes the unavailability of a single channel which must be bypassed during testing. The minimization of the unavailability is illustrated by curve 1 o Figure 4.2-2, which assumes that a channel has a failure rate of 0.1 x 10g/ hour and 0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> is required to test it. The unavailability is a minimum at a test interval 1, of 3.6 X 103 hours0.00119 days <br />0.0286 hours <br />1.703042e-4 weeks <br />3.91915e-5 months <br />.

j If two similar channels are used in a one-out-of-two configuration, the test 4

interval for minimum availability changes as a function of the rules for testing.. The simplest case is to test each one independent of the~other. In this case, there is assumed to be a finite probability that both may be bypassed j at one time. This case is shown by curve 2. Note that the unavailability is

lower, as expected for a redundant systen, and the minimum occurs at the see test interval. Thus, if the two channels are tested independently, the equation above yields the test interval for minimum unavailability.

A more usual case is that the testing is not done independently. If both channels are bypassed and tested at the see time, the result is shown in curve 3. Note that the minimum occurs at about 40,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, much longer than for Cases 1 and 2. Also, the minimum is not nearly as low as Case 2, which indicates that this method of testing does not taka full advantage of the redund:nt channel. Bypassing both channels for simultaneous testing should be avoider' .

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The most likely case would be to stipulate that one channel be bypassed, tested, and rectored, and then immediately following the second channel be bypassed, tested, and restored. This is shown by curve 4. Note that there is not true minimum. The curve does have a definite knee, and very little reduction in syst en unavailability is achieved by testing 'at a shorter interval than computed by the equation for a single channel.

The best test procedhre of all those examined is to perfectly stagger- the tests. This is, if the test interval la 4 months, test one of the other i channels every 2 months. This is shown in curve 5. The difference between Cases 4 and 5 is negligible. There may be other arguments, however,' that more strongly support the perfectly staggered tests, including reductions in human error.

The conclusions to be drawn are these .

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s. A one-out-of-n system any be treated the see as a single channel in' terms of choosing a test interval.

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b. More than one channel should not be bypassed for testing at any one l ,

time.

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QUAD CITIES DPR-29 Reactor water level instrtments 1-263-73A & B, HPCI high staan flow instruments .

1-2389A-D, and RPCI stem line low pressure instruments 1-2352 & 2353 have been modified to be analog trip systems. The analog trip system consists of  !

an analog sensor (transmitter) and a master / slave trip unit setup which ultimately ,

drives a trip relay. The frequency of calib' r ation and functional testing for  ;

I instrument loops of the analog trip systaa has been established in Licensing Topical Report NEDO-21617-A (December 1978). With the one-out-of-bro-taken-twice logic, NEDO-21617-A states that each trip unit be subjected to a-calibration /

j functional test frequency of one month. An adequate calibration / surveillance test interval for the transmitter is once per operating cycle.

l The radiation monitors in the ventilation duct and on the refueling floor -

which initiate building isolation and standby gas treatment operation are arranged in two one-out-of-two logic systems. The bases given above for the rod blocks apply here also and were used to arrive at the functional testing frequency.

l Based on experience at Dresden Unit I with instruments of similar design, a

testing intersal of cuce every 3 months has been found to be adequate.

The automatic pressura relief instrumentation can be considered to be a one-out-of-two logic system, and the discussion above applies to it also.

The instrumentation which is required for the postaccident condition will be

] tested and calibrat:d at regularly scheduled intervals. The basis for the t calibration and testing of this instrumentation is the same as uns discussed

above for :he reactor protection systen and the emergency core cooling systems.

Refarences

! 1. B. Epstein and A. Shiff, " Improving Availability and Readiness of Field i Equipment Through Periodic Inspection", UCRL-50451, Iaurence Radiation labore tory, p. IC, Equation (24), July 16,1968 i

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DPR-29 TABLE 4.2-1 MINIMUM TEST AND CALIBRATION FREQUENCY FOR CORE AND CONTAINMENT COOLING SYSTl!MS INSTRUMENTATION, ROD BLOCKS, AND ISOIATIONS(7)

Instrument Instrument Channel Functgal Test Ins t Checkg nt Calibration (2)

ECCS Instrumentation

1. Reactor low-low water level (1) Once/3 months

2. Once/ day Drywell high pressure (1) Once/3 months None

3. Reator low pressure (1) Once/3 months None

4. Containment spray interlock

a. 2/3 core ha.ight (1) (8) (8) None b .. Containment pressure (1) l

' Once/3 months None

5. Iow-pressure core cooling (1) Once/3 months None pump discharge l 6. Undervoltaga 4-hV essential Refueling outage Refueling outage None

Rod Blocks

1. APRM downscale (1) (3) Once/3 months

2. APRM flow varia.sle None (1) (3) Refueling outage Noea

3. IRM upscale (5) (3) (5) (3) None

4. IRM downscale (5) (3)

5. RBM upscale (5) (3) None

6. RBM downscale (1) (3) Refueling outage None (1) (3) Once/3 months None I 7. SRM specale (5) (3)

8. SRM latector not in startup (5) (3) None (5) (3) (6) None position

9. IRM detector not in startup i position (5)

10. SRM Jownscale (6) None

' (5) (3) (5) (3) None

11. High water level in scre Once/3 months Not applicable None

{ discharge volume (SDV)

12. SDV high level trip Refueling outage Not applicable None bypassed Main Stealine Isolation

1. Stem tunnel high temperature Refueling outage- Refueling outage

2. Stealine high flow No'ne (1) Once/3 months once/ day

3. Stealine low pressure (1) Once/3 monthe None 4 Stealine high radiation (1) (4) Refueling outage

5. Reactor low low water level (1) (8) (8) once/

Once/ dayday l RCIC Isolation

! 1 Stealine high flow once/3 months once/3 monthe

' None 2 harbine area high tsaperature Refueling outage- Refueling outage None l 3. , Iow reactor pressure onca/3 months Once/3 months None 3.2/4.2-16

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I DPR-29 TA312 4.2 1 (Cont'd)

Instrument Ins truest

_C_h anr el Functgal Test Calibration (2) I"**'E"'

Cheek HPCI (solation

1. Stealine high flow (l') (S) (8) None

2. Stessite, ares high temperature Refueling outage Refueling outage None

3. tow reactus preemare (1) (8) (S) None Reactor Su11 ding ventilation Sysean Isolation and Standby Treatment Syste Ieltiation

1. Ventila tion exhaust duct (1) Once/3 months once/ day radiation apoltors

2. Refuellas floor radiation (1) Once/3 months once/ day monitors Stem Je t Air Ejector Of f-Cas Isolation

1. Of f-ass radiation monitors (1) (4) Refueling outage Once/dar Control Roca ventilation Systa 14alation

1. Reactor low water level , (1) Once/3 months once/d ay

2. Drywell high preemare (1) Once/3 months None

3. Main stealine high flow (1) once/3 months once/ day 4 ventilation emeest duct (1) Once/3 months onc e/ day radiation eenitors

• Notee

1. Initially once per ponth until exposure hours (M as defined on Figure 4.1-1) are 2.0 X 10' thereaf ter, according to Figure 4.1-1 with an interval not less than 1 month nor more than 3 months. The compliation of instrianent failure rate data may include data obtained fram other boiling weer .

reactors for which the see design instrtment operates in an enviroment siallar to that of @ad-Cities traits 1 and 2 .

2. Functional . tests. calibrations, and instrument checks are not required then these instruments are not required to be operable or are tripped.

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3. This insertamentation is excepted fram the fun tlonal teor definition. The functional test shall consist of injecting a simulated electrical signal into the naamarament channel.

4 This instrtment chsemel is excepted fra the functional test definitloes and shall be calibrated uslag sientated electrical signals c=cs every 3 asethe.

S. Functional tests shall be performed before each startup with a requirei frequency not to enceed oece per week. Calibrations shall be performed during each startup or during controlled staatdowns with a required frequency not to sareed once per week.

6 The positioning mechselm shall be calibrated every refueltog outase.

7. 14 sic syste functional tests are performed as specified la the applicable sectioe for these systems.

l 8. Trip units are fumationally tested monthly. A calibraties of the trip unit is to be performed concurrent with the flanctional testing..

Tr==M tters are calib.ated once per operating cycle.

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l ATTACHMENT 2 Evaluation of Significant Hazards Consideration J

Description of Amendment Request This amendment request revises the calibration / functional test requirements for certain-instrumentation which has been converted into analog / trip unit systems-.

Basis for Proposed No Significant~ Hazards Consideration Determination The use of analog / trip units and the acceptable intervals. for their calibration and testing h.as been reviewed and accepted by the NRC in their review of General Electric Topical Report NE00-21617-A. The calibration interval of the transmitter (channel calibration) is less stringent than the current requirements on the existing equipment but nevertheless falls within the requirements of the Standard Technical Specifications. Accordingly, with the NRC's approval of the referenced Topical Report we feel this amendment requests ~ falls within the example (vi) of the guidance provided by the NRC in 48 FR 14870.

Therefore, since the application for amendment involves a proposed change that is similar to an example for which no significant hazards consideration exists, Commonwealth Edison has made a proposed determination that the application involves no significant hazards consideration.

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