ML17325A073

Responds to 870420 Telcon W/D Wigginton & C Tinkler Re Util 870210 Request for Ice Condenser Surveillance Interval Extension for Facility Cycle 9

ML17325A073
Person / Time
Site:	Cook
Issue date:	04/30/1987
From:	Alexich M INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	Harold Denton NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
AEP:NRC:0967I, AEP:NRC:967I, NUDOCS 8705050166
Download: ML17325A073 (25)

Text

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ACCESSION NBR: 8705050166 DQC. DATE.: 87/04/30 NOTARIZED: NO DOCKET 0 FACIL: 50-315 Donald C. Cool Nuclear Pouer Plant> Unit 1> Indiana 5 05000315 AUTH. NANE AUTHOR AFFILIATI QN ALEXICH l'l. P. Indiana Cc Nichigan Electric Co.

RECIP. NAl'lE RECIPIENT AFFILIATION Document Control Branch (Document Control'Desk)

SUBJECT:

Responds to 870420 telcon U/D Wigginton C Tinkler re 8c util 870210 request for ice condenser surveillance'interval extension for abaci)itg Cycle DISTRIBUTION CODE: AOOID TITLE: QR COPIES RECEIVED: LTR Submittal: General Distribution i ENCL / SIIE: /5 NOTES:

RECIPIENT CQPIEB RECIPIENT COPIES ID CODE/NANE LTTR ENCL ID CODE/NAl'1E LTTR ENCL PD3-3 LA 0 PD3-3 PD 5 5 llIQQINQTQN D 1 INTERNAL: ARN/DAF/LFNB 1 0 NRR/DEBT/ADE 1 NRR/DEBT/ADB 1 NRR/DOEA/TSB 1

/ILRB 1 OGC/HDS1 0 REQ FILE 01 1 EXTERNAL: EQM BRUBKEp S 1 LPDR NRC PDR 1 1 NBIC TOTAL NUl'lBER OF COPIEB REQUIRED: LTTR 18 ENCL 15

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INDIANA 8 MICHIGAN ELECTRIC COMPANY P.O. 80X 16631 COLUM8US, OHIO 43216 April 30, 1987 AEP:NRC:0967I Donald C. Cook Nuclear Plant Unit No. 1 Docket No. 50-315 License No. DPR-58 ICE CONDENSER SURVEILLANCE INTERVAL EXTENSION FOR UNIT 1 CYCLE 9 U.S. Nuclear Regulatory Commissi'on Attn: Document Control Desk Washington, D.C. 20555 Attn: H. R. Denton

Dear Mr. Denton:

This letter responds to the April 20, 1987 telephone conversation with Messrs. David Wigginton and Charles Tinkler of your staff. Mr. Tinkler asked a number of questions regarding our February 10, 1987 request (AEP:NRC:0967H) for an ice condenser surveillance interval extension for Unit 1 Cycle 9. The responses to those questions are given below.

Question 1. Were the ice weight calculations extrapolated to July 1, 1987, or July 31, 1987?

Response: The ice weight calculations were extrapolated to July 31, 1987.

Question 2. What is the date to which the surveillance interval extension is needed'?

Response: We request an extension to July 31, 1987.

Question 3. How does the most recent weighing compare with the five most recent weighings?

Response: We have compared the most recent weight losses with the four previous weight losses and also with the average of the five most recent weight losses. Twenty-five percent of the bays and seventeen percent of the row groups had ice loss significantly greater in the most recent interval than in the previous intervals, at the 958 confidence level. These larger ice losses would not be expected in the present operating cycle, since few air-handling units have been out of operation recently. This is discussed further in the response to Question 4.

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AEP:NRC:0967I Question 4. What maintenance has been performed over previous weighing intervals'E Response: Although no major maintenance has been done in recent cycles, we have checked the number of air-handling units that were turned off and out of service during the most recent periods of plant operation. There are 60 air-handling units available by design. These units are frequently referred to as 30 pairs of 2 units, though each unit is independent with its own air intake, motor, and glycol chiller. The average number of units that were turned off during a particular month of operation is tabulated below.

Avg No. of Air Handling 0 eratin Period Month ear Units Turned Off 6/86 - 4/87 4/87 3 3/87 2 2/87 3 1/87 4 12/86 5 11/86 3 10/86 5 9/86 4 8/86 4 7/86 3 6/86 8 12/85 - 6/86 6/86 13 5/86 8 4/86 7 3/86 4 2/86 1 1/86 3 12/85 3 9/85 - 12/85 12/85 6 11/85 2 10/85 4 9/85 7 6/85 - 9/85 9/85 7 8/85 5 7/85 5 6/85 10 8/84 - 4/85 4/85 2 3/85 1 2/85 unavailable 1/85 1 12/84 1 11/84 1 10/84 2 9/84 3 8/84 3 8/83 - 8/84 8/84 5 7/84 5 6/84 3 5/84 3

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AEP:NRC:09671 e 4/84 4 3/84 3 2/84 1/84 3 12/83 6 11/83 4 10/83 6 9/83 3 There is some overlap in the operating periods, which results in different averages in the same month. Except for a few cases with a large number of units off, there seems to be no overt trend of fewer units off in recent cycles. The present operating cycle (6/86-4/87) seems to have fewer units off than did the previous cycle (12/85-6/86)--4 compared to 5.6. Other units that were operating may have had varying amounts of ice buildup on the air intake that reduces efficiency.

Quantification of the ice buildup or reduced efficiency was not available.

The dates of the six most recent weighings are 06/02/86 to 06/05/86 12/03/85 to 12/06/85 09/03/85 to 09/04/85 04/15/85 to 07/19/85 07/25/84 to 08/27/84 07/18/83 to 09/12/83 The dates of the refueling outages are 06/27/87 - (Scheduled)

None in 1986 04/06/85 - 11/17/85 None in 1984 07/16/83 - 10/24/83 Question 5. Has there been any maintenance or ice replenishment since the last weighing2 Response: There has been 1,

no'ajor maintenance and no ice replenishment since the last weighing. Air-handling units were discussed in response to Question 4. Ice was replenished during the refueling outages of April 6, 1985 to November 17, 1985 and July 16, 1983 to October 24,,1983. Ice is not added during ordinary surveillances, only during refueling outages.

Question 6. During the recent 'shutdown did plant personnel check to determine whether the Row 1 and Row 9 baskets were -frozen in place'P Response: During the recent shutdown (April 8, 1987 to April 20, 1987) we did not check to determine whether Row 1 and Row 9 baskets were frozen in place. Due to the short outage period it not possible to prepare to perform a T/S ice weighing without

'was unnecessarily delaying our return to power.

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AEP:NRC:09671 -4.-

Question 7. Why is it appropriate to use the average ice weight and subtract from it the upper limit of the 95% confidence interval of the average weight loss per yearV What would be the effect of using the lower 95% confidence limit of the ice weight and subtract from that the average weight loss per yearV Response: To support our request for the surveillance extension we needed to determine the expected or average ice weight loss per year at a 95% confidence level. The weight loss then is the statistical var'iable determined from "as-left" and "as-found" weighings. The weight loss is the difference between the as-left and as-found weights, normalized to a weight loss/yr. These as-left and as-found weighings were treated as paired observations for each bay. The average ice weights were treated as data. This method of paired observations is discussed in R. E. Walpole's text, Introduction to Statistics, 2nd edition, and is quite appropriate for this analysis.

We did not believe there was reason to consider any additional statistical methods such as the lower 95% confidence level of ice weight and average weight loss. Responding to the staff's request, however, we have repeated the analysis using this technique and found that the projected ice weights for each bay and row-group are greater than the T/S limit of 1220 pounds. This technique is not as conservative as the method we used originally because the standard deviation of the ice weights is much less than the standard deviation of the ice weight losses.

We have also subtracted the most, recent weight loss from the average ice weights. All ice weights projected to July 31, 1987 remained above the 1220 pound T/S limit.

Furthermore, when the most recent ice weight losses were subtracted from the lower 95% confidence limit of ice weights there were two bays and one row group below the 1220 T/S limit, but none below the 1098 weight allowed by the T/S Bases. The projected ice condenser weight is greater than the minimum required for safe operation. The total ice weight extrapolated to July 31, 1987 was always greater than 2,590,000 pounds regardless of averaging technique. This is far greater than the 2,371,450 pound minimum required by T/Ss.

The results of all these new calculations are in Attachment 1.

Question 8: Have there been any events at the plant since June 1986 such as the inadvertent opening of the lower inlet doors that would lead us to believe that the next surveillance will be different from any past surveillance or average of past surveillancesV Response: Our April 29, 1987 telephone conversation with D. C. Cook Plant ice condenser personnel indicated there have been no significant events such as door openings or defrosting that would affect melting or ice weights on the next surveillance.

Air-handling units were discussed in response to Question 3.

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AEP:NRC:0967I Based on numerous ice weight samples and calculations, we are convinced that the Unit 1 ice condenser will have more than sufficient ice mass, with proper distribution, to completely mitigate the consequences of the design-basis accident.

The calculations used to support our previous submittal (AEP:NRC:0967H) treated any ice weight gains as zero ice weight losses instead of negative weight losses. This zero weight loss keeps the average weight loss higher, and we believed, would provide a more conservative prediction of ice weight for July 31, 1987. However, the zero weight loss approach results in a small standard deviation associated with the average weight loss, and for this reason gives a less conservative prediction of ice basket weight. The standard deviation associated with treating weight gains as negative weight losses is larger and results in the more conservative calculation, though the average weight loss is smaller.

We have repeated the ice weight predictions based on the average ice basket weight and the upper 95% confidence limit average weight loss, treating the weight gains as negative weight losses. The results are tabulated in Attachment 2. Table 1 lists the June 1986 as-left average ice basket weights and the expected weights on July 31, 1987 for each bay.

All bays except Nos. 1, 7, 8, 10, and 24 are expected to have average basket weights above 1220 pounds at the lower 95% confidence level. Bays 1, 7, 8, 10, and 24 are expected to have average basket weights above 1098 pounds at the lower 95% confidence level.

Table 2 lists the June 1986 as-left average ice basket weights for each row-group required to be weighed by T/S 4.6.5.l.b.2 and the expected weights on July 31, 1987. All row-groups except Nos. 1-1, 1-2, 2-2, 4-1, 4-2, 4-3, and 9-3 are expected to have average basket weights above 1220 pounds at the lower 95% confidence level. These anticipated lower ice weights are a result of a statistical anomaly due to some relatively large weight gains in one other surveillance period. Two of the row-groups are below 1098 pounds at the lower 95% confidence level. They are Nos. 1-2 (1048 pounds) and Nos. 4-3 (1061 pounds). We believe these weights, although conservative, would not adversely affect public health and safety since the current FSAR analysis is based on a total ice mass of 2,000,000 pounds, which corresponds to an average ice basket weight of 1029 pounds.

Table 3 lists the total ice weight expected on July 31, 1987. The ice condenser is expected to have at least 2,400,000 pounds of ice at the lower 95% confidence level on July 31, 1987. This is well above the 2,371,450 pound limit of T/S 4.6.5.1.b.2 and 2,000,000 pound limit of the FSAR analysis. The total ice weights were calculated using the predicted average bay basket weights and the predicted average row-group basket weights at the lower 958 confidence level. The weights for Rows 3, 5, and 7 were estimated as the average of the two adjacent row-groups.

It was not necessary to repeat calculations which used the most recent ice weight losses, since using a zero weight loss instead of a negative weight loss (gain) is conservative. There is no standard deviation associated with the most recent weight loss, since single observation.

it is treated as a

AEP:NRC:0967I This document has been prepared following Corporate procedures which incorporate a reasonable set of controls to insure its accuracy and completeness prior to signature by the undersigned.

Very truly yours, M. . Alexi h Vice President cm Attachment cc: John E. Dolan W. G. Smith, Jr. - Bridgman R. C. Callen G. Bruchmann G. Charnoff NRC Resident Inspector - Bridgman A. B. Davis - Region III Administrator to AEP:NRC:0967I Ice Weight Tables

Attachment 1 to AE .. C:0967I Page 1 I

TABLE 1 Projected Ice Weights per Basket by Bay Based on Lower 95% Confidence Level on Basket Weight

~Ba P 1 1361 46.0 1311 2 1436 21, 1434 3 1439 3.6 1435

4. 1413 28.5 1382 5 1346 41.5 1301 6 1345 28.8 1314 7 1332 67.6 1259 8 1380 51.3 1324 9 1382 54.9 1322 10 1345 44.5 1297 11 1410 16.1 1392 12 1363 37.5 1322 13 1391 35.5 1352 14 1389 33.0 1353 15 1398 21.9 1375 16 1388 49.2 1334 17 1422 43.9 1375 18 1420 23.1 1395 19 1408 8.0 1400 20 1377 26.3 1348 21 1387 42.6 1340 22 1410 36.5 1371 23 1435 32.9 1400 24 1388 116.2 1263 Projected Total Ice Weight 2,624,300 A - Average ice weight per basket (lbs) at the lower 95% confidence level.

As-left June 1986.

d Average ice weight loss per basket per year (lbs/yr) over the last 5 surveillances.

P Projected ice weight per basket (lbs) on July 31, 1987.

P A-d(13/12).

Attachment 1 to AE . RC: 09 67 I TABLE 2 Projected Ice Weights Per Basket by Row- Group Based on Lower 9 5 % Confidence Level on Basket Weights

~Row - G o o u l-l 1309 63.4 1241 1-2 1384 81.3 1295 1-3 1501 36.2 1461 2-1 1342 30.4 1310 2-2 1410 41.6 1365 2-3 1447 37.0 1407 4-1 1340 52.0 1284 4-2 1332 41.6 1287 4-3 1367 69.7 1292 6-1 1459 20.4 1437 6-2 1480 13.5 1466 6-3 1418 30.2 1386 8-1 1426 51.4 1371 8-2 1405 49.0 1352 8-3 1417 59.6 1352 9-1 1393 35.0 1356 9-2 1454 74.4 1374 9-3 1417 106.4 1301 Projected Total Ice Weight 2,631,800*

A Average ice weight per basket (lbs) at the lower 95% confidence level.

As-left June 1986.

d Average ice weight loss per basket per year (lbs/yr) over the last 5 surveillances.

P - Projected ice weight per basket (lbs) on July 31, 1987.

P A-d(13/12).

+Averaged Row-Groups 3, 5 and 7 by 2+4, 4+6 and 8+6, respectively.

Attachment 1 to AEP: RC:0967I ~,

TABLE 3 Pr'ojected Ice Weights Per Basket by Bay Based on Most Recent Ice Weight Loss

~Ba d5 Pl P2 1 1387 1361 226 1142* 1117*

2 1480 1436 0 1480 1436 3 1483 1439 0 1483 1439 4 1471 1413 10 1461 1403 5 1407 1346 146 1248 1187*

6 1391 1345 52 1334 1288 7 1380 1332 78 1295 1247 8 1434 1380 0 1434 1380 9 1436 1382 0 1436 1382 10 1410 1345 88 1314 1249 11 1472 1410 22 1449 1387 12 1423 1363 114 1299 1239 13 1433 1391 122 1300 1258 14 1435 1389 82 1347 1301 15 1452 1398 36 1413 1359 16 1440 1388 88 1344 1292 17 1451 1422 28 1420 1389 18 1469 1420 2 1466 1417 19 1456 1408 28 1425 1377 20 1491 1377 0 1491 1377 21 1432 1387 66 1360 1315 22 1454 1410 62 1386 1342 23 1482 1435 0 1482 1435 24 1430 1388 2 1428 1386 Projected Total Ice Weight 2,692,200 2,592,200 Y Average ice weight per basket (lbs) as-left June 1986.

A - Average ice weight per basket (lbs) at the lower 95% confidence level.

As-left June 1986.

d5 - Most recent ice weight loss per basket per year (lbs/yr).

Pl Projected ice weight per basket on July 31, 1987 based on Y, Pl-Y-d5(13/12).

P2 Projected ice weight per basket on July 31, 1987 based on A, P2 A-d5(13/12).

• Below 1220 lbs. but above 1098 lbs.

to AE C:0967I TABLE 4 Projected Ice Weights Per Basket by Row-Group Based on Most Recent Ice Weight Loss

~Row - G woo d5 Pl P2 l-l 1397 1309 110 1277 1189*

1-2 1437 1384 14 1421 1368 1-3 1578 1501 0 1578 1501 2-1 1392 1342 86 1298 1248 2-2 1439 1410 50 1384 1355 2-3 1467 1447 0 1467 1447 4-] 1356 1340 22 1332 1316 4-2 1352 1332 98 1245 1225 4-3 1391 1367 0 1391 1367 6-1 1469 1459 48 1417 1407 6-2 1502 1480 30 1469 1447 6-3 1445 1418 36 1406 1379 8-1 1451 1426 60 1386 1361 8-2 1430 1405 112 1308 1283 8-3 1441 1417 34 1404 1380 9-1 1447 1393 96 1343 1289 9-2 1484 1454 50 1429 1399 9-3 1450 1417 16 1532 1399 2,690,700 2,630,700 Projected Total Ice Weight Y - Average ice weight per basket (lbs) as-left June 1986.

A Average ice weight per basket (lbs) at the lower 95% confidence level.

As-left June 1986.

d5 Most recent ice weight loss per basket per year (lbs/yr).'l Projected ice weight per basket on July 31, 1987 based on Y, Pl Y-(j5(13/12).

P2 Projected ice weight per basket on July 31, 1987 based on A, P2 A-d5(13/12).

~Below 1220 lbs. but above 1098 lbs.

~~Averaged Row-Groups 3, 5 and 7 by 2+4, 4+6 and 8+6, respectively.

Attachment 2 to AEP:NRC:0967I Ice Weight Tables Weight Gains Treated as Negative Losses to AEP: RC:0967I Page 1 TABLE 1 Average Ice Weights per Basket by Bay Expected Average Ice Weight/

Ice Weight/ Expected Basket at Basket Ice Weight/ Lower 95%

As Left Basket Conf. Level June 1986 July 1987 July 1987

~Bs No . ~lbs. ~lbs . ~lbs .

1 1387 1435 1170 2 1480 1529 1477 3 1483 1531 1440 4 1471 1521 1332 5 1407 1437 1244 6 1391 1400 1267 7 1380 1372 1108 8 1434 1462 1185 9 1436 1441 1232 10 1410 1457 ll 12 1472 1490 1159 1415 1423 1451 1273 13 1433 1457 1280 14 1435 1453 1284 15 1452 1491 1303 16 1440 1431 1267 17 1451 1460 1259 18 1469 1515 1293 19 1456 1480 1398 20 1491 1541 1355 21 1432 1434 1283 22 1454 1460 1317 23 1482 1522 1221 24 1430" 1313 1129

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Attachment 2 to AEP: RC:0967I Page 2 TABLE 2 Expected Average Ice Weights per Basket by Row-Group Average Ice Weight/

Ice Weight/ Expected Basket at Basket Ice Weight/ Lower 95%

As Left Basket Conf. Level Row No. June 1986 July 1987 July 1987

~Gs su Ns . ~lbs . ~lb s ~lbs .

1-1 1397 1419 1148 1-2 1437 1474 1048 1-3 1578 1666 1357 2-1 1392 1426 1272 2-2 1439 1517 1178 2-3 1467 1501 1271 4-1 1356 1385 1102 4-2 1353 1399 1183 4-3 1391 1426 1061 6-1 1469 1479 1374 6-2 1502 1517 1448 6-3 1446 1427 1358 8-1 1451 1440 1288 8-2 1430 1396 1284 8-3 1441 1389 1259 9-1 1447 1431 1341 9-2 1484 1450 1255 9-3 1450 1339 1161

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Attachment 2 to AE : RC:09671 Page 3 TABLE 3 Total Ice Weight Expected on July 31, 1987 Based on Average Ice Basket Weights Based on Average at the Lower 95%

Ice Basket Wei hts ConEidence Level

~B~Ba ~B~Ba B Row-Grou 2,841,800 2,811,500 2,480,100 2,422,900

DISTRIBUTION:

+Docket- Files PKreutzer

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DWigginton April 29, 1987 PDIII-3 r/f DOCKET NO(S). 50-315/316 Mr. John Dolan, Vice President Indiana. and Michigan Electric Company c/o American Electric Power Service Corporation 1 Riverside Plaza Columbus, OH 43216

SUBJECT:

DONALD C. COOK NUCLEAR PLANTS The following documents concerning our review of the subject facility are transmitted for your information.

Notice of Receipt of Application, dated Draft/Final Environmental Statement, dated Notice of Availability of Draft/Final Environmental Statement, dated Safety Evaluation Report, or Supplement No. dated Environmental Assessment and Finding of No Significant Impact, dated Notice of Consideration of Issuance of Facility Operating License or Amendment to Facility Operating License, dated Q Bi-Weekly Notice; Applications and Amendments to Operating Licenses Involving No Significant Hazards Considerations, dated Apr 22~8~ [see page(s) 3 Exemption, dated Construction Permit No. CPPR- , Amendment No. dated Facility Operating License No. , Amendment No. dated Order Extending Construction Completion Date, dated Monthly Operating Report for transmitted by letter dated

+ Annual/Semi-Annual Report-transmitted by letter dated Office of Nuclear Reactor Regulation Encl osures:

As stated cc: See Next Page OFFICE)

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,SURNAME/

DATE P 4/g.g/87-

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NRC FORM 3I8 IIO/80)NRCM 0240 OFFICiAL RECORD COPY

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Mr. John Dolan Donald C. Cook Nuclear Plant Indiana and Michigan Electric Company CC:

Mr. M. P. Alexich The Honorable John E. Grotberg Vice President United States House of Representatives Nuclear Operations Washington, DC 20515 American Electric Power Service Corporation 1 Riverside Plaza Columbus, Ohio Regional Administrator, Region III 43215 U.S. Nuclear Regulatory Commission 799 Roosevelt Road Attorney General Glen Ellyn, Illinois 60137 Department of Attorney General 525 West Ottawa Street J. Feinstein Lansing, Michigan 48913 American Electric Power Service Corporation Township Supervisor 1 Riverside Plaza Lake Township Hall Columbus, Ohio 43216 Post Office Box 818 Bridgeman, Michigan 49106 W. G. Smith, Jr., Plant Manager Donald C. Cook Nuclear Plant Post Office Box 458 Bridgman, Michigan 49106 U.S. Nuclear Regulatory Commission Resident Inspectors Office 7700 Red Arrow Highway Stevensville, Michigan 49127 Gerald Charno ff, Esquire Shaw, Pittman, Potts and Trowbridge 2300 N Street, N.W.

Washington, DC 20037 Mayor, City of Bridgeman Post Office Box 366 Bridgeman, Michigan 49106 Special Assistant to the Governor Room 1 - State Capitol Lansing, Michigan .48909 Nuclear Facilities and Environmental Monitoring Section Office Division of Radiological Health Department of Public Health 3500 N. Logan Street Post Office Box 30035 Lansing, Michigan 48909