Text

Proposed Tech Specs,Changing Incore Analysis Program
	ML18057A423
Person / Time
Site:	Palisades
Issue date:	08/24/1990
From:	; CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	;
Shared Package
ML18057A421	List: ML18057A420; ML18057A422; ML18057A423;
References
	NUDOCS 9008310082
	Download: ML18057A423 (39)
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ATTACHMENT 1 Consumers Power Company Palisades Plant Docket 50-255 PROPOSED TECHNICAL SPECIFICATION PAGE CHANGES August 24, 1990 9008310082 900024 I I PDR ADOCK o50002ss f 7 Pages p '

-PNU-L_.J - - - _./

TSP-0890-0399-NL02

3 .11 POWER DISTRIBUTION INSTRUMENTATION 3.11.1 INCORE DETECTORS LIMITING CONDITION FOR OPERATION The incore detection system shall be operable:

a. With at least 160 of the 215 possible incore detectors and I 2 incores per axial level per core quadrant.

b. With the incore alarming function of the datalogger operable and alarm set points entered into the datalogger.

APPLICABILITY (1)' Item a. above is applicable when the incore detection system is used for:

Measuring quadrant power tilt, Measuring radial peaking factors, Measuring linear heat rate (LHR), or Determining target Axial Off set (AO) and excore monitoring allowable power level.

(2) Items a. and b. above are applicable when the incore detection system is used for monitoring LHR with automatic alarms. (Incore Alarm System).

ACTION 1:

With less than the required number of incore detectors, do not use the system for the measuring and calibration functions under (1) above.

ACTION 2:

With the alarming function of the datalogger inoperable, do not use the system for automatic monitoring of LHR (Inoperable Incore Alarm System).

3-65 Amendment No i0, ~~.

TSP-0890-0399-NL02

POWER DISTRIBUTION LIMITS 3.23.1 LINEAR HEAT RATE (LHR)

LIMITING CONDITION FOR OPERATION ACTION 3:

If the incore alarm system is inoperable and the excore monitoring system is not being used to monitor LHR, operation at less than or equal to 85% of rated power may continue provided that incore readings are recorded manually. Readings shall be taken on a minimum of 10 individual detectors per quadrant (to *include a total number of 160 detectors in a I 10-hour period) within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months and at least every 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months thereafter. If readings indicate a local power level equal to or greater than the alarm setpoints, the action specified in ACTION 1 above shall be taken.

Basis The limitation of LHR ensures that, in the event of a LOCA, 1

the peak temperature of the cladding will not exceed 2200°F.C)

Either of the two core power distribution monitoring systems (the incore alarm system or the excore monitoring system) provides adequate monitoring of the core power distribution and is capable of verifying that the LHR does not exceed its limits. The incore alarm system performs this function by continuously monitoring the local power at many points throughout the core and comparing the measurements to predetermined setpoints above which the limit on LHR could be exceeded. The excore monitoring system performs this function by providing comparison of the measured core AO with predetermined AO limits based on incore measurements. An Excore Monitoring Allowable Power Level (APL), which may be less than rated power, is applied when using the excore monitoring system to ensure that the AO limits adequately restrict the LHR to less than the limiting values. C4 )

If the incore alarm system and the excore monitoring system are both inoperable, power will be reduced to provide margin between the actual peak LHR and the LHR limits and the incore readings

-*-will be manually collected at the terminal blocks in the control room utilizing a suitable signal detector. If this is not feasible with the manpower available, the reactor power will be reduced to a point below which it is improbable that the LHR limits could be exceeded.

3-104 Amendment No. ~S, St, ttS, TSP-0890-0399-NL02

POWER DISTRIBUTION LIMITS 3.23.1 LINEAR HEAT RATE (LHR)

LIMITING CONDITION FOR OPERATION Basis (Contd)

The time interval of 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and the minimum of 10 detectors per quadrant are sufficient to maintain adequate surveillance of the core power distribution to detect significant changes until the monitoring systems are returned to service.

To ensure that the design margin of safety is maintained, the determination of both the incore alarm setpoints and the APL ( )

5 takes into account the local LHGR measurement uncertainty factors I given in Table 3.23-3, an engineering uncertainty factor of 1.03, I and a thermal power measurement uncertainty factor of 1.02. I References (1) ANF-88-107 (2) (Deleted)

(3) (Deleted)

(4) XN-NF-80-4 7 (5) FSAR Section 3.3.2.5 I (6) FSAR Section 7.6.2.4 I 3-105 Amendment No. ~S. ttS, (next page is 3-107)

TSP-0890~0399-NL02

. ;. .

TABLE 3.23-1 LINEAR HEAT RATE LIMITS No. of Fuel Rods in Ass'em5ly 208 216 Peak Rod 15.28 kW/ft 15.28 kW/ft TABLE 3.23-2 RADIAL PEAKING FACTOR LIMITS,FL Peaking Factor No. of Fuel Rods in Assembly 208 216 Assembly FA 1.48 1.50 r

Interior Rod F~H r 1. 70 1. 73 ~.. \.....

TABLE 3.23-3 I POWER DISTRIBUTION MEASUREMENT UNCERTAINTY FACTORS I I

I LHR/Peaking Factor Measurement ) Measuremenfb) Measurement( ) I P9-rameter Uncertainty a Uncertainty Uncertainty c I I

I LHR 0.0623 0.0664 0.0795 I I

FA 0.0401 0.0490 0.0695 I r I F~h 0.0455 0.0526 0.-0722 I r

I I

(a) Measurement uncertainty for reload cores using all fresh I incore detectors. I (b) Measurement uncertainty for reload cores using a mixture I of fresh and once-burned incore detectors. I (c) Measurement uncertainty when quadrant power tilt, as determined I using i~g~re measurements and an incore analysis computer I program , exceeds 2.8% but is less than or equal to 5%. I 3-107 Amendment No. ~S, tis, TSP-0890-0399-NL02

POWER DISTRIBUTION LIMITS 3.23.2 RADIAL PEAKING FACTORS LIMITING CONDITION FOR OPERATION The radial peaking factors ~, and F.t:.H shall be less than or equal :.it(,t r r the value. in Table 3. 23-2 -times the following quantity. The quantity is [1.0 + 0.3 (1 - P)] for P ~ .5 and the quantity is 1.15 for P <~.§~

P is the core thermal power in fraction of rated power.

APPLICABILITY: Power operation above 25% of rated power.

ACTION:

1. For P < 50% of rated with any radial peaking factor exceeding._;:fct~ limit, be in at least hot shutdown within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

2. For P > 50% of rated with any radial peaking factor exceeding:::1iS~ limit, reduce-thermal power within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months to less than the lowest value of:

F

[1 - 3.33 ..L.!_ - 1) ] x Rated Power FL Where F is the measured value of either ~ or F.t:.H and FL is the _._..._, c:

r r' r corresponding limit from Table 3.23-2.

Basis The limitations on~. and F.t:.H are provided to ensure that assemptic:ins used r r in the analysis for establishing DNB margin, LHR and the thermal margin/low-pressure and variable high-power trip set points remain valid during operation. Data from the incore detectors are used for determining the -

measured radial peaking factors. The periodic surveillance requirements for determining the measured radial peaking factors provide assurance that they remain within prescribed limits. Determining the measured radial peaking factors after each fuel loading prior to exceeding 50% of rated power provides additional assurance that the core is properly loaded.

To ensure that the design margin of safety is maintained, the determination I of radial peaking ft!yors takes into account the appropriate measurement I uncertainty factors given in Table 3.23-3. I References I (1) FSAR Section 3.3.2.5 I 3-111 Amendment No. ~S. ttS, TSP-0890-0399-NL02

POWER DISTRIBUTION LIMITS 3.23.3 QUADRANT POWER TILT - T LIMITING CONDITION FOR OPERATION The quadrant power tilt (T) shall not exceed 5% ..

q APPLICABILITY: Power operation above 25% of rated power.

ACTION:

1. With quadrant power tilt determined to exceed 5% but less than or equal to 10%.

a. Correct the quadrant power tilt within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months after exceeding the limit, or

b. Determine within the next 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months s* and, at least once every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter, that the radial peaking factors are within the limits of Section 3.23.2, or

c. Reduce power, at the normal shutdown rate, to less than 85% of rated power and determine that the radial peaking factors are within the limits of Section 3.23.2. At reduced power, determine at least once every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months that the radial peaking factors are within the limits of Section 3.23.2.

2. With quadrant power tilt determined to exceed 10%:

a. Correct the quadrant power tilt within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months after exceeding the limit, or

b. Reduce power to less than 50% of rated power within the next 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and determine that the radial peaking factors are within the limits of Section 3.23.2. At reduced power, determine at least once every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months that the radial peaking factors are within the limits of Section 3.23.2.

3. With the quadrant power tilt determined to exceed 15%, be in at least hot standby within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

Basis Limitations on quadrant power tilt are provided to ensure that design safety margins are maintained. Q~adrant_power tilt is determined from excore (l) detector r*eadings which are calibrated using incore detector measurements.

I measurements and an incore analysis computer program. 2 Quadrant power tilt calibration factors are determine~ ysing incore I

3-112 Amendment No. ~$, ll$,

TSP-0890-0399-NL02

e POWER DISTRIBUTION LIMITS 3.23.3 QUADRANT POWER TILT - T LIMITING CONDITION FOR OPERATION References (1) FSAR, Section 7.4.2.2 (2) FSAR Section 7.6.2.4 I 3-113 Amendment No. ~~.

TSP-0890-0399-NL02

ATTACHMENT 2 Consumers Power Company Palisades Plant Docket 50-255 MARKED-UP TECHNICAL SPECIFICATION PAGES August 24, 1990 7 Pages TSP-0890-0399-NL02

f' ~I 3.11 POW'SR-DISTRIBUTION INSTRUMENTATION 3 . 11 . 1 INCORE DETECTORS LIMITING CONDITION FOR OPERATION The incore detection system shall be operable:

j(,b ~1S"po5~16le.

a. With at least .a. of the'i incore. detectors and 2 incores per axial level per core quadrant.

b. With the incore alarming function of the datalogger operable and alarm set points entered into the datalogger.

APPLICABILITY (1) Item a. above is applicable when the incore detection system is used for:

Measuring quadrant power tilt, Measuring radial peaking factors, Measuring linear heat rate (I.HR), or Determining target Axial Offset (AO) and excore monitoring allowable power level.

(2) Items a. and b. above are applicable when the incore detection system is used for monitoring I.HR with automatic alarms.

(Incore Alarm System.)

ACTION 1:

With less than the required number of incore detectors, do not use the system for the measuring and calibration functions under (1) abov~.

ACTION 2: With the alarming function of the datalogger inoperable, do not use the system for automatic monitoring of I.HR (Inoperable Incore Alarm System).

Amendment No .Jg, r/~

nul281*0445a*43*71 3*65 ..Seeemee~ 8 1 1981

.:.-:;.;~;..: -.._. _

t

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POWER DISTRIBUTION LIMITS 3.23.1 LINEAR HEAT RATE (LHR)

LIMITING CONDITION FOR OPERATION ACTION 3:

If the incore alarm system is inoperable and the excore monitoring system is not being used to monitor LHR, operation at less than or equal to 85% of rated power may continue provided that incore readings are recorded manually. Readings shall be taken on a minimum of 10 individual deJ;!_ctorscper.

quadrant (to include-.:t-d "tl:l:B~otal number oelf!'etectors* in a I 10-hour period) within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months 1nd at least ev~y i hours * .

thereafter. If readings indicate a local power level equal to or greater than the alarm setpoints., the action specified* in.

ACTION 1 above shall be taken. ** **

Basis i.: '.

The limitation of LHR ensures that, in the event of a LOCA, *the peak temperature of the cladding will not exceed 2200°F. (1)

Either of the two core power distribution monitoring systems (the incore alarm system or the excore monitoring system) provides adequate monitoring of the core power distribution and is capable of verifying that the LHR does not exceed its limits. The incore alarm system performs this function by continuously monitoring the local power at many points throughout the core and comparing the measurements to predetermined setpoints above which the limit on LHR could be exceeded. The excore monitoring system performs this function by providing comparison of the measured core AO with predetermined AO limits based on incore measurements. An Excore Monitoring Allowable Power Level (APL), which may be less than rated power, is applied when using the excore monitoring system to ensure that the AO limits adequately restrict the LHR to less 4

thazf: the limiting values. < >

If the incore alarm system and the excore monitoring system are both inoperable, power will be reduced to provide.margin between the actual peak LHR and the LHR limits and the incore readings will be manually collected at the terminal blocks in the control room utilizing a suitable signal detector. If this is not feasible with the manpower available, the reactor power will be reduced to a point be~ow which it is improbable that the LHR limits could be ex~eeded.

3-104 Amendment No. ' ' ' 8Z,° ~j!

Hooambez 13, 198&

TSP1088-0181-NL04

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POWER DISTRIBUTION LIMITS 3.23. l **-t:fNEAR HEAT RATE (LHR)

LIMITING CONDITION FOR OPERATION Basis (Contd)

The time interval of 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and the minimum of 10 detectors per quadrant are sufficient to maintain adequate surveillance of the core power distribution to detect significant changes until the monitoring systems are returned to service.

To ensure that the design margin of safety is maintained, the determination of ~~F-h !~&: 1 ip~f13 alarm setpoj°fr;"-~1 J}]!~A?..x 7'..6/e 3..13-3..I takes into accountl\:ifmeas\n:4~!i~ uncer~Jn.t91~ ,...,. &iltO, an engineering uncertainty factor of 1.03, a thermal power measurement uncertainty factor of 1. 02,\aci aUeltilartce hll' q1:1 hat

~.

References (1) ANF-88-107 (2) (Deleted)

(3) (Deleted)

(4) XN-NF-80-47 (s~ PsA~ Sed-1t>Y\ ~ 3 ..J. s

[l,.') f5A'2- ~c.im~ /. lc,.~.4 3-lOS Amendment No. '8, tJ.t

-He?emher lS, 1988 (next page is 3-107)

TSP1088-0181-NL04

TABLE 3. 23-J;.

LINEAR HEAT RATE LIMITS No. of Fuel Rods in Assembly I 208 216 Peak Rod 15.28 kW/ft 15.28 kW/ft TABLE 3.23-2 RADIAL PEAKING FACTOR LIMITS,FL Peaking Factor No. of Fuel Rods in Assembly .

208 21~

Assembly pA 1.48 1.50 r

Interior Rod ~B 1. 70 1. 73 r

TA ell. 3. :J.3.-~

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-A" r Y' 0 .~ss 3-107 C).OS.:lb t>. 01~.i

.,_J Amendment no. H, 1ff

'- ~e uambaz 3:5 ; l~ &.

TSP D888-0105-HL04.

. -* . .'* J.~ **

POWER DISTRIBUTION LIMITS 3.23.2 RADIAL PEAKING FACTORS LIMITING CONDITION FOR OPERATION The radial peaking factors rA,r and F~H shall be less than or equal to r

the value in Table 3.23-2 times the following quantity. The quantity is [l.O + 0.3 (1 - P)] for P > .5 and the quantity is 1.15 for P < .5. P is the core thermal power in fraction of rated power.

APPLICABILITY: Power operation above 25% of rated power.

ACTION*:

1. For P < 50% of rated with any radial peaking factor exceeding its limit, be in at least hot shutdown within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

2. For P > 50% of rated with any radial peaking factor exceeding its limit, reduce thermal power within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months to less than the lowest value of:

F

[l - 3.33 ( .r - 1) ] x Rated Power FL Where Fr is the measured value of either r!* or F~H and FL is the corresponding limit from Table 3.23-2.

Basis

~ ~ . .

The limitations on F""~, and Fr are provided to ensure that assumptions used in the analysis for establishing DNB margin, LHR and the thermal margin/low-pressure and variable high-power trip set points remain valid during operation. Data from the incore detectors are used for determining the measured radial peaking factors. The periodic surveillance requirements for determining the measured radial peaking factors provide assurance that they remain within prescribed limits. Determining the measured radial peaking factors after each fuel loading prior to exceeding 50% of rated power provides additional assurance that the core is properly loaded. **

To e~~u...-e ia.+ .fk des~V\ M~~1Y°l 1 ~£~~ t6 ~;....b~~ +-le. Jek~*~<<-~~"r\

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wr,cel/'\cS~'-'1 ~ ~r _s (t) Jll)ell\ LVI la.blc. ~ .~ *3 * *

~e~e~<eS (1) fs1-1~ ~ci10" 3J..;<. =r 3-111 Amendment No. '8, /.A, N"i;"aml:Ui is, uee TSP1088-0181-NL04

POWER DISTRIBUTION LIMITS 3.23.3 Q~NT POWER TILT - T -

LIMITING CONDITION FOR OPERATION The quadrant power tilt (T ) shall not exceed 5%.

q APPLICABILITY: Power operation above 25% of rated power.

ACTION:

1. With quadrant power tilt determined to exceed S%*but less than or

, equal to 10%.

a. Correct the quadrant power tilt within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months after exceeding the limit, or

b. Determine within the next 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and, at least once every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter, that the radial peaking factors are within the limits of Section 3.23.2, or

c. Reduce power, at the normal shutdown rate, to less than 85%

of rated power and determine that the radial peaking factors :i1 are within the limits of Section 3.23.2. At reduced power, 0'.,:

dete~ine at least once every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months that the radial peaking factors are within the limits of Section 3.23.2.

2. With quadrant power tilt determined to exceed 10%:

a. Correct the quadrant power tilt within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months after exceeding the limit, or

b. Reduce power to less than 50% of rated power within the next 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and determine that the radial peaking factors are within the limits of Section 3.23.2. At reduced power, determine at least once every 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months that the radial peaking factors are within the limits of Section 3.23.2.

3. With the quadrant power tilt determined to exceed 15%, be in at least hot standby within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

Basis Limitations o.P-quadrant power tilt are provided to ensure that design safety margins are maintained. Quadr11nt power tilt is determined from excore detector-readings which are calibrated using incore detector (l,).Cli~~- ~~a~ea~~~~

~~~~& uadr~

r. m measurements. y fo g w d e n , fu -c re s f e i o i n t e n a r a n t o e c nc ~ ~ gs *

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\IA.e4..c;,~~-fi %0 Ct.4'\, l ... c.ore. J-U2 lleVW6ife_ U, 1988 -

TSP1088-0181-NL04

POWER DISTRIBUTION LntITS 3.23.3 QUADRANT POw'ER TILT

Tq LIMITING CONDITION* FOR OPERATION References

.I (1) FSAR," Section.7.4.2.2 nul281.*0445a*43*71 ,

Amendment No U 3-113 Heccmbei W; llik

"I)

ATTACHMENT 3 Consumers Power Company Palisades Plant Docket 50-255 PALISADES INCORE ALGORITHM (PIDAL)

ANALYSIS OF QUADRANT POWER TILT UNCERTAINTIES August 24, 1990 15 Pages TSP-0890-0399-NL02

PALISADES INCORE DETECTOR ALGORITHM (PIDAL)

ANALYSIS OF QUADRANT POWER TILT UNCERTAINTIES G.A. Baustian Consumers Power Company August 14,1990 1

CONTENTS 1: Objective 2: Summary of Results 3: Assumptions 4: Analysis Methodology 5: Analysis Results 6: Palisades Core Map 2

Objective The purpose of the work described by this analysis was to determine the accuracy of the full core PIDAL power distribution calculations when the true core power distribution is radially tilted. This is in response to comments made by the USNRC while reviewing the PIDAL methodology and uncertainty analysis.

In particular, the NRC requested the following_:

1- A comparison of the tilt measured by PIDAL with the true or theoretical tilt.

2- Verification that the PIDAL code programming was correct by supplying theoretical detector input and comparing the resulting PIDAL solution with . the original theoretical power distribution solution.

3- Determination of the SF(s) uncertainty component for radially perturbed or tilted power distributions up to the full power Technical Specification limit of 5% quadrant power tilt.

4- An explanation of what assumptions are made in the Palisades Safety Analysis to cover radial peaking factor increases caused by quadrant power tilts.*

3

Summary and Conclusions Comparisons between the quadrant power tilts determined by the PIDAL model were made to corresponding theoretical values. It was found that in all cases PIDAL either accurately measured the quadrant power tilt, or in some instances conservatively measured the tilts to be greater than truth.

The SF(s) uncertainty component as defined in the PIDAL uncertainty analysis was recalculated for radially tilted cores. It was found that in all cases the SF(s) value for tilted cores was bounded by the value used in the PIDAL uncertainty analysis for cores with quadrant power tilts up to 2.8%. It was also found that the value of the SF(s) uncertainty component depended strongly on the direction and magnitude of the oscillation causing the power tilt. For cores oscillating about the diagonal core axis, the assumed PIDAL measurement uncertainty is valid for tilts up to 5%.

For the oscillation about the core major axis, the SF(s) uncertainty component ceases to be bounded by the value assumed in the PIDAL uncertainty analysis for quadrant power tilts greater than 2.8%. Since the Palisades Technical Specifications allow for full power operation with quadrant power tilts of up to 5%, and it was clear that the current PIDAL uncertainties were only valid for tilts up to 2.8%, it was necessary to derive new uncertainties to allow use of PIDAL for tilts above 2.8%. An analysis was performed, as described in Sections 3 ahd 4 of this report in order to determine the uncertainties in Fl,

~hand F~ at the 5% quadrant powe.r tilt threshold. These uncertainties may be found in Table #3 of Section 5 of this report.

It was shown that the coding in the PIDAL program is correct by reproducing a theoretically flat power distribution when given the appropriate theoretical incore detector values. This is in agreement with results previously obtained as part of the PIDAL Uncertainty Analysis.

Finally, it was found that quadrant power tilt is not an input to the Safety Analysis and that the increase in local or radial peaking resulting from a tilted core scenario is implied by the peaking factor or LHGR used in the analysis. There is no tilt multiplication factor applied to the peaking factors. - -

4

Assumptions The Palisades FSAR specifically talks about three types of instabilities within the

. reactor core: radial, azimuthal and axial. This analysis is .only concerned with the first two modes. It is assumed that the use of the word "radial" in the FSAR refers to an oscillation which moves from the center of the core outward to the periphery and then back. An oscillation of this type could be depicted by the top of a single spired circus tent being raised and lowered. It is assumed that the word "azimuthal" refers to an oscillation which traverses the entire width or the core before returning back to the point of origination. In the rigorous sense of the word, this type of oscillation could hypothetically traverse circumferentially around the core as weli, much like a pie tin would rotate if it were not perfectly balanced on a central point.

The Palisades FSAR states that a radial oscillation in the reactor is highly unlikely and stable if it does occur. To this end, there are times when the word "radial" is used loosely, meaning either a truly radial oscillation, or sometimes meaning "about the radial plane". It is hoped that the context of the usage will clearly dictate the meaning.

There is one fundamental difference between the uncertainties derived from this analysis and the original va.lues derived in the PIDAL Uncertainty Analysis which was brought on by the nature in which this analysis had to be performed. In the original PIDAL uncertainty analysis, it was assumed that the SF(s) uncertainty components contained both the measured and inferred components of the box power synthesis uncertainty. For this analysis, the SF(s) uncertainties calculated do not contain the same component because the detector powers supplied to PIDAL are based on theory. Since no data for significantly tilted cores exists for the Palisades reactor, it must be assumed that recalculating the uncertainty components based purely on theoretical detector powers is valid.

5

Analysis Methodology In order to answer the questions posed by the NRC, it was necessary to supply PIDAL with incore detector signals from a variety of radially tilted configurations. It was desired to investigate the effects of quadrant power tilts on the order of 0% to 5%, as well as more severely tilted cases on the order of 10%.

The 0% to 5% tilt range was chosen because this covered the range over which the Palisades reactor can operate at greater than 25% power while remaining within the quadrant power tilt guidelines set forth in Palisades Technical Specification 3.23.3. At the present time, power operation with quadrant power tilts greater than 5% is not anticipated since tilts of this magnitude are highly unlikely unless a dropped control rod or otherwise severe localized power anomaly occ:urs. Nevertheless, it was deemed necessary to investigate how well PIDAL performed when more severe tilts were present.

Since Palisades rarely operates with measured quadrant power tilts greater than 1%,

and measured incore detector signals for radially tilted cores were not available, it was necessary to find an alternate method for providing PIDAL wit~ the required tilted incore detector data. It was decided to use detector powers derived from full core XTG solutions as input to PIDAL. This required that XTG cases be run which modelled radial or azimuthal imbalances in the reactor core.

A total of four XTG cases were run in order to model a variety of azimuthal and radial Xenon oscillation scenarios. Three of the four XTG runs started from a restart corresponding to roughly 3 / 4 total cycle length. The fourth case was run at BOC. These four cases all started the transient by dropping a single control rod into the core and then leaving the rod fully inserted for a period of 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months after which time the rod was rapidly pulled out. The ensuing transient was then followed for a period of 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months . The only differences between the four transient cases run were which control rod was dropped and therefore

.which direction the oscillation took across the core.

The first two of the transient cases were run by dropping group 3 control rods into the core. The first case dropped in a group 3-outer rod (rod 3-34) while the second case dropped in the central control rod (rod 3-33). The object of the case which dropped in the 3-outer rod was to induce an azimuthal oscillation. The object of dropping the central rod was to see if a i:adial oscillation could be induced.

The second two cases run both used a group 4 control rod as the transient initiator.

The object of these two cases was to initiate an azimuthal oscillation which started off of the major axis (on a diagonal). Both of the two cases which used a dropped group 4 control rod as transient initiator were identical with the exception being that the first case was run at 3/ 4 cycle length while the second case was run at BOC.

6 J*

Analysis Methodology After the XTG cases were run, it was necessary to infer theoretical incore detector powers from the resultant three-dimensional XTG power distributions. This was accomplished by writing a small utility program, XTGDET, which used tl).e power distribution from the XTG punch file as input.

The purpose of the XTGDET program was to read in a 3-D power distribution punch file created by XTG and convert the nodal powers into equivalent incore detector powers. Subroutine EXPAND is the meat of the XTGDET program. Based on the 3-D

nodal power distribution determined by XTG, it calculates the theoretical detector powers.

EXPAND uses the same methodology as subroutine EXPAND of PIDAL and Section 2.2.1 of the PIDAL Methodology Report should be consulted _if further reference is required.

The XTGDET program was compiled and link edited four times. The program was identical for each compilation except for the incore detector location array, DETLOC. For.

the first compile DETLOC defined the actual locations of the detector strings in the reactor core (i.e. DETLOC was defined just like it was in the PIDAL block data section). For the second compilation the incore detectors spatial orientation to each other was not changed, but the entire core was rotated 90° clockwise underneath them. The third and fourth compiles rotated the core 180° and 270° clockwise respectively from its true orientation to the* incore detector strings. The reason for wanting to rotate the core about the incore detector locations will be discussed shortly.

Once the theoretical detector powers were obtained for the radially tilted conditions, they were input to PIDAL. The core power distributions calculated by PIDAL were then compared back to the original XTG solution. For each of the PIDAL cases run, the statistical analysis option was chosen in order to determine the uncertainties associated with the PIDAL calculations for the tilted conditions.

Prior to discussing the actual PIDAL cases which were run, it is appropriate to describe the temporary modifications which were made to the cycle 7 PIDAL model in order to overlay the measured incore detector signals with the full core theoretical values supplied by XTG via XTGDET. In the m,ain program,. immediately after the call to Subroutine BXPWR (which calculates the detector powers based on measured millivolt signals and the Wprimes), temporary coding was added which reads in the theoretical detector powers and detector level normalization factors produced by XTGDET. This read was activated by the IXPOW flag which is normally used to tell PIDAL to use theoretical detector powers from the 1/4 core XTG model that runs concurrently with each PIDAL case. Following the input of the full core theoretical detector powers, the IXPOW flag was turned off so that the normal 1/4 core theoretical detector power logic in PIDAL would not take effect. Note that the measured detector powers are actually overlaid by the new coding and that PIDAL assumes the full core theoretical values to be measured from this point on.

7

c r ..

"" ( ..

Analysis Methodology A total of 19 PIDAL cases were run for this analysis. The first case was a non-tilted base case which corresponds to the core conditions at 3/ 4 EOC. The XTG case used to supply the full core theoretical detector powers was the second step of the 3/4 EOC group 4 rod drop scenario. The base case is important because it serves to verify that the entire system is working as designed for this analysis. The following checks were made: '

- Verification that the full core XTG model for cycle 7 is working properly by comparing the full core XTG run with the 1/4 core XTG power distribution of PIDAL.

- Verification that the XTGDET program is working properly by comparing the full core XTG power distribution with the XTGDET collapsed 2-D radial power distribution.

- Verification that the XTGDET program is working properly by comparing the XTGDET theoretical detector powers with those previously calculated by the 1/4 XTG which is part of PIDAL.

- Verification that the full core .detector signals are getting input to PIDAL correctly from XTGDET and that the PIDAL solution is correct by comparing the PIDAL solution with the original XTG solutfon.

With description of the base case out of the way, discussion on the remaining 18 PIDAL cases is appropriate. The PIDAL cases run used theoretical detector powers from two of the XTG dropped rod induced transient scenarios. The first 6 PIDAL cases used powers from the 3/4 EOC group 4 rod induced transient while the second 6 used powers from the group 3-outer rod induced XTG case.

The first six PIDAL cases run corresponded to peak quadrant power tilts of i0%,

7.6%, 5.6%, 2.9%, 1.6% and 03% respectively. These~cases were selected because they covered the spectrum of tilted cores for a tilt range of no tilt up to 10% tilt. Concentration on tilts between 0% and -5% was greater because it is over this range that the reactor may be operated without reducing power or correcting the tilt. The second six PIDAL cases all lie within the no tilt and -5% quadrant power tilt range.

-s

Analysis Methodology There were two reasons for using the two different transient scenarios as suppliers of the theoretical detector powers. First, the dropped group 3-outer rod scenario did not result in quadrant power tilts greater than 5% during the oscillatory period. Therefore, it was necessary to use cases from the dropped group 4 rod scenario in order to get results on tilts up to 10%. Secondly, the oscillations between the two scenarios were quite different.

The dropped group 3-outer rod oscillated about the major symmetric axis while the dropped group 4 rod scenario oscillated about the diagonal axis. Consideration of both. is important because the majority of the symmetric incore detector locations are rotationally symmetric (and not generally symmetric about either major axis or diagonal) and therefore oscillations about differing axis' could have differing effects on the accuracy of the PIDAL quadrant power tilt algorithm.

Expanding on this last statement, it was decided to further investigate the effects of tilt location on .the PIDAL solution. In the case of the dropped group 4 rod induced

.transient, the power peak used for the PIDAL cases 1 through 6 occurred in quadrant 2.

What if the power peak was in one of the other three quadrants? In other words, what if the power distribution was the same, just rotated 90°, 180° or 270°? Since the. incore detectors are not equally distributed over the quadrants,, it is not expected that. the power distributions as measured by PIDAL would be the same for the rotated cases. The same questions can be asked for the group 3-outer rod induced transient as well.

The XTGDET program allowed for use of the same XTG case for each of the four

possible symmetric oscillations induced by individually dropped group 4 rods. In a similar fashion, the existing group-3 outer dropped rod XTG case could be used for three additiOnal symmetric transient* scenarios.

Six additional PIDAL cases were then run. Three of the cases were for the 5% tilted group 4 rod induced oscillation at rotations of 90°, 180° and 270° clockwise from the original power distribution. The other three cases were for the 5% tilted group 3-outer rod induced transient at rotations of 90°, 180° and 270°.

9

": r

Analysis Results The results of the three transient cases which caused azimuthal xenon transients are summarized in Table #1. From this table it is apparent that the core is less stable at beginning of cycle than at EOC azimuthally. This is in agreement of Section 3.3.2.8 of the .

Palisades FSAR which states that it appears that the azimuthal mode is the most easily excited at beginning of life even though the axial mode becomes the most unstable later.

From Table #1 it is also clear that the oscillation resulting from the group 4 rod drop is more severe from a quadrant power tilt standpoint than for the group* 3-outer rod drop.

The reason for this is that in the group 3-outer induced transient, the power peaking is symmetric along the quadrant lines, and therefore the peak tilt is actually distributed over two adjacent quadrants. In the case of the dropped group 4 *rod transient, the power peaking is symmetric about the diagonal which lies within a single quadrant.

Table #2 presents the results of the PIDAL cases which were run and it is this data that will be used to answer the questions asked by the NRC. The first NRC request was for comparison of the tilt measured by PIDAL with the true or theoretical tilt. For the dropped group 4 rod case, the agreement between the PIDAL solution and the original XTG quadrant power tilt was very good: For the true tilts between 0% and 10%, the error was on the order of 0.72% or less. -

For the dropped group 3-outer rod induced transient, the quadrant power tilt was not as accurately measured, however it was measured conservatively in each case. For true quadrant power tilts of -4% or less, the PIDAL tilt was still within 1% of the original XTG.

When the true tilt rose to greater than 5% the error in the PIDAL tilt calculation reached 1.23%. Again it should be noted that the PIDAL tilt for these cases was always higher than the true tilt and therefore conservative:

The second NRC comment asked that the PIDAL code programming be verified correct by supplying theoretical detector input and comparing the resulting PIDAL solution with the original theoretical power distribution solution. In actuality, this comment had already been addressed by the PIDAL Uncertainty Analysis. The SF(r) _uncertainty component represents the error in the PIDAL solution when PIDAL is given detector powers from a known power distribution solution. For the entire data base, the SF(r uncertainty component was 0.0022. This value is in excellent agreement with the individua~

case SF(r) uncertainty components found on the statistical summary edit following each of

_the PIDAL runs performed for this analysis.

10

..v**

Analysis Results

The third comment made by the NRC requested that a determination of the SF(s) uncertainty component for tilted cores be made. To this end, the PIDAL statistical analysis routines, which calculate the individual case uncertainty components, were activated for each

. of the eighteen tilted core PIDAL runs made. The individual results are presented in Table

2. When looking at .these values, the reader should keep in mind the overall SF(s) uncertainty component of 0.0277 for the entire data base arrived at in PIDAL Uncertainty Analysis. Based on the results presented in Table #2 it can be concluded that the uncertainty component SF(s) bounds core measurements up to quadrant power tilts of 2.8%

(linear interpolation between cases 9 and 10). Furthermore, depending on the direction of the oscillation, the PIDAL measurements are bounded to above the current 5% quadrant power tilt Technical Specification limit.

For the oscillation symmetric about the core diagonal, the PIDAL measurement uncertainty previously determined is valid for tilts up to 5%. For the oscillation about the core major axis, the SF(s) uncertainty component ceases to bound the value assumed in the PIDAL uncertainty analysis for quadrant power tilts greater than 2.8%. This means.that the uncertainties derived in the PIDAL Uncertainty Analysis are not valid for all cases when*

quarter core tilts are greater than 2.8%.

Because it was shown that the current uncertainties do not bound all tilted cases, it was necessary to find new uncertainties which take power distributions with tilts greater than 2.8% into account. This was done by utilizing the PIDAL statistical processor program, to combine the data from PIDAL cases 13 through 18. The PIDAL statistical program, which was developed and documented as recorded in the PIDAL Uncertainty Analysis, can take statistical data output by individual PIDAL cases and .combine it to represent an entire population. Cases 13 through 18 were used as the basis for the new tilted core uncertainty because they all were based on theoretical tilts of roughly 5% (actually 5.58% and 5.11%).

The 5% quadrant power tilt cut-off was specified because Technical Specification 3.23.3 allows for full power operation of the reactor for quadrant power tilts up to 5%, without any compensatory action.

The results of the statistical combination for the tilted cases may be found in Table

3. The non-tilted data presented is taken from the previous PIDAL Uncertainty Analysis.*

The Fl, ~h and F~ data presentedin Table #3 is the basis for the revised Technical Specification Table 3.23.3.

Iri response to the fourth NRC comment, a discussion on how quadrant power tilt

effected the Palisades Safety-Analysis took place with members of the Palisades Transient Analysis Group. It was learned that quadrant power tilt is not an input to the Safety Analysis and that the increase in local.or radial peaking resulting from a tilted core scenario is implied by the peaking factor or LHGR used in the analysis. There is no tilt multiplication factor applied to the peaking factors.

11

Analysis Results Table #1 Step Hours Group 3-0uter . Group 4 Group 4 from drop 3/4 EOC TILT 3/4 EOC TILT BOC TILT 1 0 1.0000 1.0000 1.0000 2 0 1.0627 1.0708 1.0708 3 72 1.0488 1.0542 1.0505 4 73 1.0191 1.0410 1.0458 5 74 1.0329 1.0697 1.0777.

6 75 1.0424 1.0892 1.1011 7 76 1.0483 1.1007 1.1162 8 77. 1.0510 1.1057 1.1238 9 78 1.0511 1.1054 1.1251 10 79 1.0495 1.1013 1.1212 11 80 1.0459 1.0941 1.1133 12 81 1.0416 1.0854 1.1025 13 82 1.0369 1.0757 1.0898 14 83 1.0318 1.0657 . 1.0761 15 84 1.0266 1.0558 1.0621

16. 85 1.0217 1.0463 1.0484 17 86 1.0171 L0374 . 1.0354*

18 87 1.0129 1.0294 1.0236 19 88 1.0092 1.0222 1.0132 20 89 1.0060 1.0160 1.0043 21 90 1.0033 1.0108 1.0104 22 91 1.0011 1.0065 1.0145 23 92 1.0006 1.0030 1.0173 24 . 93 1.0018 1.0036 1.0189 25 94 1.0027 1.0045 1.0194 26 95 1.0033 1.0051 1.0190 27 96 1.0036 1.0054 1.0177 28 97 1.0038 1.0054 1.0159 29 98 1.0037 1.0053 1.0136 Table # 1 - Peak quadrant power tilts for three scenarios each initiated by dropping a control rod, leaving it inserted for 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months and then rapidly withdrawing it. Values predicted by Palisades cycle 7 full core XTG model.

12

. f

~*

Analysis Results Table #2 Case Initiating XTG PIDAL % Tilt SF(s) SF(sa)

Rod Tilt Tilt Error BASE 1.0000 1.0000 0.0000 0.0010 0.0008 1 4 1.1013 1.0959 -0.54 0.0376 0.0321 2 4 . 1.0757 1.0721 -0.36 0.0280 0.0242 3 4 1.0558 1.0533 -0.25 0.0198 0.0180 4 4 1.0294 1.0284 -0.10 0.0101 0.0102 5 4 1.0160 1.0158 -0.02 0.0077 0.0066 6 4 l.0030 1.0037 0.07 0.0089 0.0044 7 3-0uter 1.0511 1.0634 1.23 0.0495 0.0445 8 3-0uter 1.0416 1.0520 1.04 0.0409 0.0367 9 3-0uter 1.0318 1.0403 0.85 0.0313 *0.0289 10 3-0uter 1.0217 1.0282 0.65 0.0219 0.0211 11 3-0uter 1.0092 1.0132 0.40 0.0112 0.0112 12 3-0uter 1.0006 1.0014 0.08 0.0083 0.0035 13 4 1.0558 1.0486 -0.72 . 0.0239 0.0217 14 3-0uter 1.0511 1.0606 0.95 0.0529 0.0476 15 4 1.0558 1.0533 -0.25 0.0207 . 0.0188 16 3-0uter 1.0511 1.0634 i.23* 0.0490 0.0439 17 4 1.0558 1.0486 -0.72 0.0228 0.0205 18 3-0uter 1.0511 1.0606 0.95 0.0533 0.0480 Table #2 - Quadrant power tilts and detector power uncertainty components for for PIDAL for radially tilted cores.

Note: For all scenarios, PIDAL correctly identified the quadrant in which the

maximum quadrant tilt occurred.

Cases 13 and 14 were for a core rotated 90° CW under the incores.

Cases 15 and 16 were for a core rotate,d 180° CW under the incores.

Cases 17 and 18 were for a core rotated 270° CW under the incores.

13

Analysis Results Table #3 Statistical Standard Degrees of Tolerance Tolerance Variable Deviation Freedom Factor Limit F(s) # 0.0393 1800 F(sa) # 0.0351 360 F(r) # 0.0026 408 F(s)

0.0306 3415 F(sa)

0.0241 683 F(r)

0.0021 969 F(s) 0.0277 8768 F(sa) 0.0194 1754 F(r) 0.0022 2754 F(z) 0.0151 1122' F(L) 0.0135 188 F1 # 0.0443 2487 1.703 0.0795 ph # 0.0383 489 1.766 0.0722 FA.r # 0.0352 364 1.785 0.0695 F1

0.0368 3822 1.692 0.0664 ph

0.0277 877 1.733 0.0526 FA.r

0.0242 694 1.746 0.0490 F1 0.0344 4826 1.692 0.0623 ph 0.0237 1225 1.727 0.0455 FA.r 0.0195 1790 1.712 0.0401 Table #3 - Summary of PIDAL Statistical Component Uncertainties.

-- values to be used when quadrant power tilt exceeds 2.8%

but is less than or equal to 5%.

-- values for cores with once-burnt reused incore detectors.

Note: *For the final tolerance limits, penalty factors of .0041, .0046 and .0067 for Fl, ~ h and F~ respectively were included to account for up to 25% incore detector failures.

14

Pa l . i s#des Nuc l e ' r Plant Reactor Core Plan A B C D E F G M N R S T v w x z 1 North 2

3

\ 2 3

4 Ll 5 5 6 6 7 7 a

g 10 10 1 1 L_J11 12 12 1 13 1 4.

o====;15 1 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23 A B C D E F G H ..J K R S T v w x z

~antral rod group l~I Incore detector number jcontrol rod number All instruments conta1ri 5 rhodium detectors and 1 outlet thermocouple.

--Reactor vessel level mon1tor1ng system installed 1n place of detectors 7 and 44.

Form from EGAD 13 rev1s1on O IS

I I

ATTACHMENT 4 Consumers Power Company Palisades Plant Docket 50-255 PROPOSED FSAR PAGE CHANGES August 24, 1990 9 Pages TSP-0890-0399-NL02

described in the analysis of the boron dilution incident (Section 14.3).

Section 14.3 also shows that the reactor operator has sufficient time to recognize and to take corrective action to compensate for the maximum reactivity addition due to xenon decay and cooldown.

3.3.2.5 Power Distribution The power distribution in the core, especially the peak power.density, is of major importance in determining core thermal margin. Enrichment zoning within fuel bundles is used to reduce local power peaking.

Since dissolved boron is used to control long-term reactivity changes such as burnup, the control blades do not need to be used to a great extent.

Typically, at hot full power, only Group 4 blades are in the reactor about 10% or less. This is not enough to upset the global power distribution.

Several power distribution limits have been established to protect against fuel failures. A limit on the linear heat generation rate that is a function of the axial location of the peak power in the pin protects against departure from nucleate boiling and from overheating during an LOCA. The LHGR limits are given in Section 3.23.1, Linear Heat Rate, of the Technical Specifications.

There are additional limits on the axially averaged radial peaking factors that also protect against fuel failures. These limits ensure that the margin to DNB and the linear heat generation rates are not violated during normal or transient conditions and that the thermal margin/low-pressure trip and the high-power trip set points remain valid during normal opera-tions. The peaking factors are given in Section 3.23.2, Radial Peaking Factors, of the Technical Specifications. The peaking factor definitions are:

Assembly Radial Peaking Factor - ~r The assembly radial peaking factor is the maximum ratio of individual fuel assembly power to core average assembly power integrated over the total core height, including tilt.

Total Interior Rod Radial Peaking Factor - F~H r

The.maximum product of the ratio of individual assembly power to core average assembly power times the highest interior local peaking factor integrated over the total core height including tilt.

The LHGR and peaking factor limits shown in Tables 3.23-1 and 3.23-2 of the Technical Specifications must be reduced by several factors before all necessary conservatisms are accounted for. To account for calculational uncertainties in the incore monitoring system, the limits are reduced by dividing them by the appropriate uncertainties (Reference 32) given in FS0789-0365C-TM13-TM11 3~3-7 Draft

(

' *1 Table 3-12. In addition, to account for the change of dimensions from den-sification (due to resintering) and thermal expansion, the LHGR limits are reduced by dividing them by 1.03. To account for uncertainty in the re-actor thermal power, the LHGR limits are reduced by dividing them by 1.02.

3.3.2.6 Neutron Fluence on Pressure Vessel At the end of Cycle 2, afte~ 2.26 effective full-power years of operation, a capsule containing reactor vessel construction specimens was removed *from the reactor vessel for evaluation (see Reference 17). The capsule was located at 240 degrees, just outside of the core barrel.

The neutron fluence of the specimens within the capsule was deduced from the neutron induced activity of several iron wires from the capsule. The neutron f luence for neutron energies greater than 1 MeV was determined to be 4.4 x 10 19 nvt.

The fluence at the capsule location is then adjusted by a lead factor, which is the ratio of the fast- f iux at the capsule location to the maximum fast flux at the vessel wall. The DOT-3 computer code (see Reference 19) was used to compute a value of 17.5 for this factor _(see References 17 and 18). The corresponding peak vessel fluence was determined to be 2.5 x 10 18 nvt.

A vessel wall capsule at 290 degrees location was pulled out at the end of Cycle 5 at 11.67 calendar ~ears of operation. Measured fluence levels at the capsule were 1.1 x 10 1 nvt corresponding to 5.20 effective full power years (see References 28 and 29). A lead factor of 1.28 (see Reference 28) was established to compute the peak vessel wall fluence of 8.6 x 10 18 nvt.

Recently for the Cycle 8 operation, a fluence reduction program was initi-ated. A low-leakage fuel management scheme with partial stainless steel shielding assemblies near the critical axial weld locations was employed to reduce the vessel wall flux. DOT calculations have_ been performed to compute the flux levels during the Cycle 8 operation (see Reference 30).

By this new core loading pattern, it is possible to reduce the vessel wall flux in the range 14%-51%, compared to previous cycles (see Reference 31).

Assuming 75% capacity factor for the remainder of the Plant's 40-year operational life and flux levels similar to Cycle 8 o¥eration, the maximum fast fluence the vessel wall will receive is 3.9 x 10 9 nvt. However, PTS screening criteria and Regulatory Guide 1.99, Revision 2 restrict the fluence levels to 1.6 x 10 19 nvt at the vessel axial weld locations (see Reference 31),' which corresponds to seek vessel fluence of- 2.8 x 10 19 nvt.

Further, a supplemental dosimetry program has been established. A set of dosimeters outside the vessel have_ been installed during the end ~f Cycle 7 refueling outage. These dosimeters would undergo irradiation during the entire Cycle 8 operation. At the end of Cycle 8, these dosimeters would be removed and replaced with a new set of dosimeters for Cycle 9 operation.

Irradiated dosimeters would be analyzed, and measured flux values will be determined. These measured flux values would be used for benchmarking the vessel flux/fluence calculations on a cycle-by-cycle basis.

FS0789-0365C~TM13-TMll 3.3-8 Draft

I.

TABLE 3-12 I I

POWER DISTRIBUTION MEASUREMENT UNCERTAINTIES I I

I I

I Measurement Measurement Measurement I LHGR/Peaking Factor Uncertainty Uncertainty Uncertainty I Parameter (a) (b) (c) I I

LHGR 0.0623 0.0664 0.0795 I I

F4 0.0401 0.0490 0.0695 I I

F~H 0.0455 0.0526 I I

(a) Measurement uncertainty based on the PIDAL calculational methodology for I reload-cores using all fresh incore detectors. I I

(b) Measurement uncertainty based on the PIDAL calculational methodology for I reload cores using a mixture of fresh and once-burned incore detectors. I I

(c) Measurement uncertainty when quadrant power tilt, as determined using I incore measurements and an incore analysis computer program (reference 33), I exceeds 2.80% but is less than or equal to 5%. I

... ,')'

DRAFT 3-3 FS0789-0365D-TM13-TM11

The thermocouples are of Inconel sheathed, Chromel-Alumel construction and are located at the top end of each incore detector assembly so that the primary coolant outlet temperatures may be measured. The neutron detectors in the assemblies are short rhodium detectors equally spaced. These units with their cabling are contained inside a 0.311-inch nominal diameter stainless steel sheath. Sixteen of the detectors are provided with envi-ronmentally qualified electrical connectors and cabling inside contain~ent to provide increased reliability of the thermocouple readout for monitoring the potential approach to inadequate core cooling conditions.

Assemblies are inserted into the core through eight instrumentation ports in the reactor vessel head. Each assembly is guided into position in an empty fuel tube in the center of the fuel assembly via a fixed stainless steel guide tube. The seal plug forms a pressure boundary for each as-sembly at the reactor vessel head.

The neutron detectors produce a current proportional to neutron flux by a neutron-beta reaction in the detector wire. The emitter, which is the central conductor in the coaxial detector, is ma*de of rhodium and has a high thermal neutron capture cross section.

The rhodium detectors are 40 cm long and are provided to measure flux at several axial locations in fuel assemblies. Useful life of the rhodium detectors is expected to be about three years at full power, after which the detector assemblies will be replaced by new units.

The data from the thermocouples and detectors are read out,by the PIP data processor which scans all assemblies and, periodically or on demand, prints out the data. The data processor continually computes integrated flux at each detector to update detector sensitivity factors to compensate for detector burnout. Temperature indication from the 16 qualified core exit thermocouples is also displayed on strip chart recorders in the control room and is available to be read out from the CFMS computer.

The incore instrumentation is also used for measurement of reactor core radial peaking factors and quadrant power tilt and for annunciating linear heat rate. The incore alarm system provides these last functions on a continuous basis using the Plant information processor described in Subsec-tion 7.6.2.3, annunciating in the control room.*

Verification of incore channel readings and identification of inoperable detectors are done by correlation between readings and with computed power shapes using an off-line computer program~.* Quadrant power tilt and linear heat rate can be determined from the excore nuclear instrumentation (Sub-section 7.6.2.2), provided they are calibrated against the incore readings as required by the Technical Specifications. Quadrant power tilt calibra-tion of the excore readings is performed based on.measured incore quadrant power tilt. Incore quadrant power tilt is calculated using a computer pro-gram which determines tilts based on symmetric incore detectors and/or the integral power in each quadrant of the core (Reference 12). Linear heat rate calibration of the excore readings involves two intermediary parame-ters, axial offset and allowable power level, which can be-determined by FS0789-0565G~TM13-TM11 7.6-16 Draft

i.

\.-

REFERENCES

1. Consumers Power Company, "Palisades Plant Reactor Protection System Common Mode Failure Analysis, "Docket 50-255, License DPR-20, March 1975.

2. Consumers Power Company, Response to NUREG-0737, December 19, 1980 (Item II.E.4.2 - Special Test of April 15, 1980).

3. Gwinn, D V, and Trenholme, W M, "A Log-N Period Amplifier Utilizing Statical Fluctuation Signals From a Neutron Detector, " IEEE Trans Nucl Science, NS-10(2), 1-9, April 1963.

4. Failure Mode and Effect Analysis: Auxiliary Feedwater System, Bechtel Job 12447-039, dated January 14, 1980, Letter 80-12447/039-10, File 0275, dated March 25, 1980 to Consumers Power Company's B Harshe (Consumers Power Company FC 468-3 File).

5. Vandewalle, David J, Director, Nuclear Licensing, CPCo, to Director, Nuclear Reactor Regulation, USNRC, "Proposed Technical Specification Change Request - Auxiliary Feedwater System, "September 17, 1984.

6. Zwolinski, John A, Chief, Operating Reactors Branch 5, USNRC, to David J VandeWalle, Director, Nuclear Licensing, CPCo, "Amendment No 91 -

Deletion of Technical Specification 4.13, Reactor Internals Vibration Monitoring, "September 5, 1985~

7. Johnson, B D, Consumers Power Company, to Director Nuclear Reactor Regulation, Attention Mr Dennis M Crutchfield, "Seismic Qualification of Auxiliary Feedwater System, "August 19, 1981.

8. VandeWalle, David J, Director, Nuclear Licensing, CPCo, to Director, Nuclear Reactor Regulation, USNRC, "Supplement 1 to NUREG-0737, Safety Parameter Display System, Revised Preliminary Safety Analysis Report, "August 21, 1985. *

9. Berry, Kenneth W, Director, Nuclear Licensing, CPCo, to Director, Nuclear Reactor Regulation, USNRC, "Response to Request for Additional Information, Safety Parameter Display System, "May 19, 1986.

10. Kuemin, James L, Staff Licensing Engineer, CPCo, to Director, Nuclear Reactor Regulation, USNRC, "Generic Letter 83..;.28, Salem ATWS Event, Item

1. 2, Control Rod Position, "May 5, 1986.

11. Thadani, Ashok C, Director, Nuclear Regulatory Comli:J.ission, to Kenneth W Berry, Director, Nuclear Licensing, CPCo, "NUREG-0737, Item II.F.2, Inadequate Core Cooling Instrumentation, "January 19, 1987.

12. The CPCo Full Core PIDAL System Software Description, Revision 5, I November 15, 1989, GA Baustian, Palisades Reactor Engineering. I DRAFT 7-1 FS0789-0365D-TM13-TM11

~ ~~*

~ .....,

31. Attachment to letter of R W Smedley (CPCo) to NRC (dated April 3, 1989).

"Docket-50-255 - License DPR Palisades Plant - Compliance with Pressurized Thermal Shock Rule 10 CFR 50.61 and Regulatory Guide 1.99, Revision 2 - Flu~nce Reduction Status (Tac No 59970).

32. The CPCo Full Core PIDAL System Uncertainty Analysis, Revision 2, August I 24, 1990, GA Baustian, Palisades Reactor Engineering. I

33. The CPCo Full Core PIDAL System Software Description, Revision 5, I November 15, 1989, GA Baustian, Palisades Reactor Engineering. I DRAFT 3-3 FS0789-0365D-TM13-TM11

ML18057A423

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