ML17317A929

Responds to NRC 781220 Ltr Requesting Info on Axial Power Distribution Monitoring Sys & Potential ECCS Reliability Improvements After One Year of Operation

ML17317A929
Person / Time
Site:	Cook
Issue date:	02/08/1979
From:	Bien F INDIANA MICHIGAN POWER CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
AEP:NRC:00126, AEP:NRC:126, NUDOCS 7902130163
Download: ML17317A929 (12)

Text

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BEGVLATQIY INFORMATION DISTRIBUTION SYSTEM (BIDS>

ACCESSI.ON NBR.c7902130163 DOC.DATE.~ 79/02/08 NOT .

IZED'ES DOCKET ¹ FACIL>50-316 Donald C. Cook Nuclear Power Plant, Unit 2, Indiana 8. 0500031 %

AUTH. NAhlE AUTHOR AFFILIATION BIEN,F.N. Indiana 8.:.michigan Power Co.

RECIP.NAMF RECIPIFNT'"AFFILI'ATION DENTON,H.R. Office of Nuclear Reactor Regulation SUBJECTS Responds to NRC 78,1220 ltr requesting .info on axial power distribution monitoring sys 8, potentia,l emergency core cooling sys reliability improvements after 1 year of 0 operati,on. 0 DI STRI BUTION CODE s A001S COPI ES RECEIVED:LTR Q FNCL / S I ZEr TITLE< GENERAL DISTRIBUTION FOR AFTER ISSUANCE OF OPERATING LIC NOTES i ~~N> ~ e~S-~~< 0 RFC I,P I ENT COP I ES RFCI P I ENT COP I ES I D CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL ACTION> 05 BC I-)8< 4l 7 7 INTERNAL FG FI ,1 1 02 NRC PDR 1 1 12 ICE 2 2 14 TA/EDO 1 1 15 CORE,PERF BR ~1 16 AD SYS/PROJ .1 1 17 ENGR BR 18 REAC SFTY BR

'1 1 1 1 1 19 PLANT SYS BR .1 1 20 EEB 1 I 2 I EFLT TRT S YS 1 22 BR INKMAN .I 1 EXTERNAL.t 03 LPDR .1 1 04 NSI C 1 I 23 ACRS .16 16 gal%

qq19 TOTAL NUhtBER OF COPIES REQUIRED LTTR 38 ENCL 38

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INDIANA tIr MiCHIGAN POWER COMPANY P. O. BOX 18 BOWLING GREEN STATION NEW YORK, N. Y. 10004 February 8, 1979 AEP:NRC:00126 Donald C. Cook Nuclear Plant Unit No. 2 Docket No. 50-316 License No. DPR-74 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Denton:

Attached please find our responses to the requests for information contained in the attachment to Mr. A. Schwencer's letter dated December 20, 1978 which we received on December 26, 1978. Mr.

Schwencer's letter. requested information on the Axial Power Distri-bution,Monitoring System (APDMS) and on potential Emergency Core Cooling System (ECCS) reliability improvements for Donald C. Cook Nuclear Plant Unit No. 2 after one year of operation. The requested information is contained in Attachments'A'nd 'B'o this letter.

The attached information is being submitted at the request of the NRC staff and provides additional information regarding operational experiences with previously reviewed and approved systems. In light of the above, AEPSC interprets 10 CFR 170.22 as requiring that no fee accompany this submittal. (

Reference:

10 CFR Part 170.22, Footnote (2).)

Very truly yours,

. N. Bien subscribed to before Vice President this ~

Sworn and York day of February, York 1979 me in New County, New c pc.~r Notary Public "lie 'IJ r + ~

0 O1m ii ~ vo' toro or iirw York Ctu 0rio4 rn ~,nouns County Corrific ru titrrd in Nrrw York County Lonrrniirivr.rondo rnorch o0, l97y cc: (ATTACHED)

Mr. Harold R. Denton, Director AEP:NRC:00126 cc: R. C. Callen G. Charnoff R. W. Jurgensen .

D. V. Shaller -Bridgman P. W. Steketee R. J. Vollen R. Walsh

ATTAC$1ENT 'A'O AEP:NRC:00126 A. Axial Power Distribution Monitorin S stem APDMS Re uest No. 1 (Provide) a discussion and evaluation of any operational difficulties experienced, especially instances of restricted reactor power due to down time or unavailability of the APDMS.

~Res onse The APDMS has functioned well during the first year of operation of the Donald C. Cook Nuclear Plant Unit No. 2. There were however, several minor problems with the APOMS during this time. These problems are described below.

(a) On one occasion, the full length step counter did not change indication, nor did it actuate a sequence when control bank D was withdrawn. The cause of this event was found to be the "hanging up" of relay K 8 which feeds the signal, indicating

~

Bank 0 withdrawal, to the APDMS. The relay was repaired and the APDMS returned to service. This event did not result in a power reduction.

(b) On one occasion one of the APDMS detectors withdrew from its park position near the bottom of the core to its fully withdrawn position. This detector's signal was switched out and a redun-dant detector was used to allow continued APOMS operation. In-vestigation revealed that the "problem" was a dirty relay in the detector control panel. This and the other system relays have been cleaned and inspected. No similar events have been en-countered to date.

(c) The most serious problem associated with the APOflS involved a faulty CPU input card, on loan from the vendor, which resulted in the dedicated computer's failure to output Fz and its limit comparison. The input card was replaced and the APDMS was re-turned to service. Since then, no similar events have occurred.

~ use Re uest No. 2 (Provide) A report of any situation in which power was limited by the Technical Specifications to less than 100% of design power level as a consequence of the APDMS indication (e.g., such as at beginning of cycle).

RESPONSE

At beginninq of life the unit was restri'cted to 95% power to preserve margin to FLz. Had AEPCS/IIEM not had this internal requirement to maintain margin to F" the unit could have operated at a higher power level. Table No. 1 )attached) summarizes the dates and approximate burnups at which the APDMS setpoints were changed.

l<e do not possess a reliable estimate of the lost generation due to the APDMS imposed power limit. This is due to the fact that coincident with the presence of such limits, other equipment problems prevented the Unit from achieving 100% thermal power.

Re uests No. 3 and 4 (Provide) Comparison tables of power peaking factors as measured by the incore flux maps and by the APDMS including data taken under different conditions of axial offset and burnup.

(Provide) A brief discussion of the highlights of the comparison.

RESPONSE

Table No. 2 (attached) shows a comparison between the Fq values calculated by the APDMS and from full core flux maps, respectively.

It is not possible to obtain APDMS data during the flux map data acquisition periods. The data shown in Table 2 are APDMS data taken immediately prior and/or after the flux map data acquisition period. As can be seen,,the APDMS yields, with a few exceptions, a larger or more conservative F(. Out of 73 comparisons, only 12 displayed a non-conservative APDMS FN. The maximum amount that the APDMS was non-conservative to the flux maps i)as only 1. 10%,

well within the uncertainties associated with that system. That is, the APONS F" is penalized by 12.525, whereas the flux map F( is penalized by only 8.15%. The average F) deviation is -1.29% with a standard deviation of 1.24%.

TABLE 1

SUMMARY

OF POWER LIMITATIONS DUE TO APDMS LIMITS IN CYCLE 1 OF UNIT 2 SETPOINT APPROXIMATE CHANGE DATA ~l.

• BURNUP MWD/MTU 6/8/78 95 454 6/9/78 97 472 7/12/78 98 989 7/20/78 99 1107 8/21/78 100 1477

(*) LIMITING POWER IN PERCENT

TADLS 2 COOK UNIT 2 COMPARISON ~ABLS - APDHS PcRFOih"ANCB Flux Axial AP DHS Flux APDHS )( at Flux Fq Deviation "

Offset Detector Fz Tire of APDHS Hap iqN/ Flux Map Fqp -

Hap Burnup Map Location -'00 Date Neer iOD/MTU Location Fz(Peak) (Peak) Flux Hap FqN x Flux Hap Fq" 201-18 I.CII I.C05 1.3659 1.9191 I. 9112 0 ' I 5/19/78 567.8 -9.936 P4 N2 1.414 I.CI . 1.3636 1.9227 H4 -0.60 813 1.414 1. Cl 1.3568 1.9131 -0.10 L13 1. 408 1.40 1.3717 1.9203 -0.48 201-19 ' -9.446 P4 1.398 1.39 1. 3636 1.895C 1.8989 +0.18 6/6/78 685

+1. 10 N2 1.401 1.38 1.3608 1.8779 HC 813 1. 391 'I. 395 1.3553 1.8906 +0.44 L13 1.394 1.40 I.3700 1. 9180 -1.0'I 7/10/78 201-21 1518. 6 -7. 724 PC 1.365 1.365 1.3607 1.8573 1. 83C2 -1.26 h2 1.369 1.37 1.3589 1.8616 H5 -I.BO 813 1.361 1.3558 L13 1.354 1.35 1.3665 1.8448 -0. 8 7/13/70 201 22 1625,9 7,879 PC 1.359 1.361 1.3576 1.8482 1.8272 -1.15 N2 1.369 1.36 1.3563 1.8445 H4 -0.95 813 1.362 1.3536 1.3646 1.8325

'0.29 L13 1.347 1.343 7/14/78 201-23 1669.0 -6.732 P4 1.348 1.35 1.3565 1.8313 1.7927 -2.15 N2 1.3C7 1.35 1.3526 1.8260 58 -I.Be B13 1.347 1.3517 L13 1.332 1. 33 l. 3622 1.8117 -1.06 8/7/78 201-24 1851.8 -7.033 P4 1. 350 1.35 1.3508 1.8236 'I.8170 0 N2 1.353 1.36 1.3469 1.8318 EB -0.31 813 1.351 1. 37 1.3483 1.8471 -1.66 L13 1.339 1.35 1.3582 1.8336 -0.91

-6. 568 1. 327, 1.33 1.3461 1.7903 1.7958 a 0.31 8/17/78 201-25 2217. 3 P4 N2 1.337 1.33 1.3424 I 7855 LB i0.58 813 1.327 1.32 1.3470 1.7781 +0.99 L13 1.314 1. 31 1.3557 1.7760 + 1.10 9/13/78 201-26 2906. 3 -5. 341 P4 1.301 1.29 1.3459 1.7362 1.7128 -1.35 N2 1. 310 l. 315 1.3410 1.7635

'I. 7514 HS B13 1.303 1.30 1.3473 -2.96 L13 1.284 I. 28 1.3573 1.7373 ~ 1.43 9/13/78 201-27 2914.7 -13.462 P4 1.385 1. 385 1.3459 1.8640 1.8222 -2.3C H2 1.396 1.40 1.3410 1.8774 012 813 1.399 1.40 1.3473 1.8862 -3.51 L13 1.367 1.37 1.3573 1.8595 -2.05 9/14/78 201-28 2918.2 -20.246 P4 1.429 I . 44 1. 3459 1. 9380 1. 8925 -2.41 N2 1.451 1.455 1.3410 1. 9512 Dl 2 -3.10 813 1.442 1.445 1.3473 1.9468 -2.87 L13 1.425 1.415 1.3573 1.9206 -1.48 9/14/78 201-29 2924. 8 w6. 302 P4 1.362 1.35 1.3459 1.8169 1.7943 -1.26 N2 1.367 1.355 1.3410 1.8171 H5 -1.27 813 1.371 1.35 1.3473 1. 8188 -1.37 L13 1.345 1.32 1.3573 1.7916 ~,15 4

ATTACHMENT 'B'O AEP:NRC:00126 B. ECCS and Shutdown Heat Removal S stems Reliabilit Re uest No. 1 Identify those systems or components that have encountered problems in operational reliability.

~Res onse No systems or components in the ECCS or RHR system encountered problems in operational reliability during Unit No. 2 operation.

Re uest No. 2 Discussion of any design, procedural, or equipment modifications implemented or considered as-a result of this operating experience.

~Res onse No modifications have been implemented or considered as a result of Unit No. 2 operating experience. The RHR pump seal sleeves have been modified to reduce the possibility of leakage as a result of Unit No. 1 operating experience.

s Provide an evaluation of any other potential improvements of the ECCS and shutdown heat removal systems that you have considered emphasizing reliability aspects.

~Res onse No modifications are planned for the ECCS and RHR systems.

T<LE 2 - Cont'd.

COOK UNIT 2 COHPARISON TABLE - APDHS PERFOMLNCE Flux Axial APORT Flux APDf)S K at Fq Deviation '4 Map Burnup Offset Detector Map Fz Time of APDHS Flux Hap Date Number ND/HTU Location Fz(Peak) (Peak) Flux Hap F N F N Flux Hap FqN - APDk!

100 x Flux Map Fq 10/10/78 201-30 3876.9 -5.132 P4 1.273 1.27 1.3390 1.7006 1.6716 -1.73 N2 1.285 1.285 1.3330 1.7130 04 -2.48 813 1.287 1.285 ).3388 1.7204 -2.92 L)3 1.260 1.255 1.3526 1.6975 -1.55 11/6/78 201-31 4743.8 -2.782 P4 1.260 1.26 1.3339 1.6807 1.6825 iO.) )

N2 l. 295 1.28 1.3255 1.6980 D12 -0.92 813 1.295 1.32 1-.3308 ).7567 -4,4')

L)3 1.249 1.25 1.3480 1.6850 -0. 15 11/30/78 201-32 4979.3 -3.964 P4 1.232 1.23 1.3323 1.6388 1.6412 tO.)5 N2 \.246 1.25 '1.3207 1.6508 Hl) -0.59 813 1.244 1.24 ).3237 1.6415 -0.02 L)3 ) .215 1.215 1.3454 1.6359 +0.33 12/18/78 201-33 5645.7 -2.991 P4 1.203 1.20 1. 3327 1.5992 1.5913 -0.50 N2 1.226 1 . 23 1. 3184 1. 6216 -1.90 813 1.223 1. 22 1 . 3219 1. 6127 -1.34 L)3 1.188 1.18 1.3472 1.5897 +0.10

)2/28/78 201-34 6032.6 -4.534 P4 1.215 1.22 1.3288 1. 6212 1.5643 -3.64 N2 1.218 1.23 1 ~ 3110 1.6125 H5 -3.08 B13 1. 214 1.21 1.3)46 1. 5907 -1.69 L)3 1.194 1.205 1.3442 1.6198 -3.55

)2/28/78 201-35 6038.2. -9.827 P4 1.273 1.25 1.3288 1.6610 1. 6276 -2.05 N2 1.290 ).275 1.3110 1.6715 M)2 -2.70 B)3 1.284 1.265 1.3146 1.6630 -2.18 L)3 1.258 1.225 ).3442 1.6467 -).17 12/23/78 201-36 6040.9 -18.095 P4 1.372 1.37 1.3288 1.8205 1.7609 -3.38 N2 1. 371 1.365 1.3110 1.7895 LB -1.62 813 1.361 1.35 1.3146 1.7748 -0.79 L)3 1.353 1. 345 1. 3442 1.8080 -Z.67 12/29/78 201-37 6048.1 +14.415 P4 l. 398 ).375 1.3288 1.8271 1.8101 -0.94 N2 1. 372 1. 39 1. 3110 1.8223 HS -0.67 813 1. 384 1. 39 1. 3146 1.8273 -0.95

).13 1.376 1.355 1.3442 1.8214 -0.63