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Partial Draft of Nuclear Power Plant Operating Experience - 1978, Section 3.0, Plant Outages. Portions of NUREG-0483, NUREG-0366 & NUREG-0227 (Plant Operating Experience for 1977,1976 & 1974-75,respectively) Encl
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Site:	Crane
Issue date:	12/31/1978
From:	; NRC OFFICE OF MANAGEMENT AND PROGRAM ANALYSIS (MPA)
To:	;
References
	RTR-NUREG-0227, RTR-NUREG-0366, RTR-NUREG-0483, RTR-NUREG-366, RTR-NUREG-483, TASK-TF, TASK-TMR NUDOCS 8002110656
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grygpenr y 3.1 Introduction A review of the plant outages that occurred during 1978 provides a means of assessing the nature, number, and extent of the operating problems experi-enced at nuclear power plants, as well as the principal systems and components involved. The data for this review was obtained from the data reported by the licensee for the NRC's monthly " Operating Units Status Report."

In a few cases, outage type was classified differently than reported by the licensee.

For example, where appropriate and sufficient information was available, major outages were subdivided to reflect more accurately the true nature of the work performed during the outage. Also, the forced extension of a scheduled outa3e* was generally reclassified by the NRC staff as a forced outage.* In a few cases, work that had been scheduled for later in the year was rescheduled so it could be performed during an unexpected forced outage.

These cases were classified as scheduled outages. Refueling of the reactor is also classified as a scheduled outage.

Data sheets for all the plants considered are contained in Appendix B.

In reviewing the outage data, it should be noted that there are significant differences in nuclear plant designs, even between plants of a given type.

Therefore, care should be used in interpreting the data.

3.2 Plant Outage Statistics There were 824 outages requiring 142,068 hours7.87037e-4 days 0.0189 hours 1.124339e-4 weeks 2.5874e-5 months of plant downtime reported by the 65 nuclear power plants which were in commercial operation during 1978.

See Glossary - Appendix A.

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2 The average total outage time during commercial operation was 25.1% of the 4

year; the average forced outage time was 9.1%; and the average scheduled outage time was 16.1%.

The average total unit availability for the 65 plants, con-sidering only the period when they were in commercial operation, was 75.0.*

3.3 Types of Outages Identification of types and causes of major outages for each plant in commercial operation is contained in Tables 3-la and 3-lb.

To provide an overview of plant outages,' these tables list plant availability, the hours accumulated, and percent for scheduled, forced, and total outages and the major systems and components causing outages lasting longer than five days.

As shown in these tables, these plants experienced 48 major outages for re-fueling. There were 35 major outages involving the reactor coolant system, and they af fected 28 of the 65 operating plants. There were 14 major outages attributable to steam generator problems at PWRs.

Table 3-2 summarizes the outages by type (i.e., scheduled or forced) and indicates the relative impact on plant operations. During 1978, the average number at forced outages for each nuclear plant was 10, with each outage averaging 79 hours9.143519e-4 days 0.0219 hours 1.306217e-4 weeks 3.00595e-5 months in duration.

The average number of scheduled outages was 3 per plant, with each averaging 466 hours0.00539 days 0.129 hours 7.705026e-4 weeks 1.77313e-4 months in duration.

3.4 Proximate Cause of Plant Outages Outage events and proximate causes are summarized in Ts.51e 3-3a.

Outage cause was selected by the NRC staff to be in one of the following eight categories:

The availability plus the percent total outage time exceeds 100% because, by definition, the availability factor includes " unit reserve shutdown hours" which are also counted in the " total outage time."

3 (1) refueling (scheduled), (2) equipment failure (forced), (3) maintenance or test (primarily scheduled), (4) operational error (forced), (5) regulatory restriction (forced and scheduled), (6) administrative (forced and scheduled),

(7) training and licensing (scheduled), and (8) other.

The operational error category includes any plant personnel errors which caused a forced outage.

Scheduled refuelings required the most outage time of all causes with 60,975 hours0.0113 days 0.271 hours 0.00161 weeks 3.709875e-4 months (43%). Equipment failures (forced) accounted for 42,841 hours0.00973 days 0.234 hours 0.00139 weeks 3.200005e-4 months or 30% of all outage time.

Scheduled maintenance or testing consumed 20,193 hours0.00223 days 0.0536 hours 3.191138e-4 weeks 7.34365e-5 months - 14%.

Regulatory restrictions

accounted for another 9,413 hours0.00478 days 0.115 hours 6.828704e-4 weeks 1.571465e-4 months (7%)

of scheduled outage time. Humboldt Bay accounted for 8,760 hours0.0088 days 0.211 hours 0.00126 weeks 2.8918e-4 months of the outage time due to regulatory restrictions. The plant was shut down all year for seismic modification continuing a shutdown which accounted for 1,344 hours0.00398 days 0.0956 hours 5.687831e-4 weeks 1.30892e-4 months in 1976 and 8,760 hours0.0088 days 0.211 hours 0.00126 weeks 2.8918e-4 months in 1977.

Although the number of plants considered in this review increased f rom 61 in 1977 to 65 in 1978 (7%), there was a decrease in total outage hours of 107 hours0.00124 days 0.0297 hours 1.76918e-4 weeks 4.07135e-5 months a similar trend also occurred from 1976 to 1977.

Equipment failures (forced) showed an increase of 12,296 hours0.00343 days 0.0822 hours 4.89418e-4 weeks 1.12628e-4 months (40%), over that required in 1977, while the refueling time decreased by 5,682 hours0.00789 days 0.189 hours 0.00113 weeks 2.59501e-4 months and the time for maintenance or testing decreased 8,425 hours0.00492 days 0.118 hours 7.027116e-4 weeks 1.617125e-4 months .

Table 3-3b lists the ratio of outage hours for the various causes to 100 operational hours. These numbers may also be considered as the percent of time expended for each cause.

In 1978, there were 25 BWRs commercially

See Glossary - Appendix A.

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4 operable all year -- 8760 hrs. Therefore the total number of operating hours considered for BWRs was' 219,000 hours0 days 0 hours 0 weeks 0 months .

For the PWRs, there were 38 units commercially operable all year, one unit was operable 50% of the year, and one unit was operable 57% of the year, providing a total of 342,253 operating hours for the PWRs.

The table indicates that PWRs (as a class) required about 17% more time for refuelings than'was required at BWRs. Actually, table 3-3a indi-cates that on the average, each refueling outage at a BWR required 976 hours0.0113 days 0.271 hours 0.00161 weeks 3.71368e-4 months ; whereas, each refueling outage at a PWR required 1316 hours0.0152 days 0.366 hours 0.00218 weeks 5.00738e-4 months - 340 hours0.00394 days 0.0944 hours 5.621693e-4 weeks 1.2937e-4 months '(35%)

more than that required at a BWR.

The time expended at PWRs for maintenance or testing was significantly greater than that required at BWRs - 2.6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months /100 operating hours or 123%

more time.

Four of the 4.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months listed under regulatory restrictions.was due to the shutdown at llumboldt Bay for the entire year. Thus, this one o

plant shutdown was primarily responsible for BWRs expending 300% more time than PWRs for outages due to regulatory restrictions.

The time required for equipment failures and operational errors was about the same for both types of plants. Outage time for administrative reasons, training and licensing, and other reasons were relatively insignifi-cant.

3.5 Systems and Components Associated With Plant Outages A graphic representation of plant outages is shown in Tables 3-4 and 3-5.

These tables classify outages by type, and identify system, component, plant, J

5 and cause.. Outage duration in hours and the percent of the total outage time

.is listed for major groupings. The size of each box is proportional to the hours involved'to the nearest 1%.

The system and component classifications I

]

used in this report are listed in Appendix B.

Because of the fundamental differences between BWRs and PWRs, they are discussed separately.

3.5.1 Boiling-Water Reactors I

Forced Outages j

Two hundred twenty-nine forced outages accouuled for 34% of the total BWR outage time in 1978 - 18,554 of 54,174 hours0.00201 days 0.0483 hours 2.876984e-4 weeks 6.6207e-5 months . As indicated in Tabic 3-4, i

the reactor coolant system accounted for nearly half of the forced outage

. time with 9,155 hours0.00179 days 0.0431 hours 2.562831e-4 weeks 5.89775e-5 months , or 17% of the total. The steam and power system ac-counted for 2,561 hours0.00649 days 0.156 hours 9.275794e-4 weeks 2.134605e-4 months (5%), and the engineered safety features accounted for 2,075 hours8.680556e-4 days 0.0208 hours 1.240079e-4 weeks 2.85375e-5 months (4%). The electric power system and the reactor system each f

accounted for 3% of the total outage time, while the radwaste system accounted j

for 2% and the instrumentation and control system accounted for 1%.

The major components involved were piping (5,949 hrs), valves (1767 hrs), pumps (1608 hrs), control rod drives (1281 hrs) and shock absorbers (1042 hrs). Duane Arnold accumulated 4752 hrs of outage time due to piping failure; Big Rock Point accumulated 1281 hrs of outage time due to control 1

rod drive problems; and Vermont Yankee accumulated 1042 hrs of outage time i

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attributed to shock absorber failure.

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i Scheduled Outages Scheduled outages in BWRs totalled 35,620. hours, or 66% of the total BWR outage time. Refuelings accounted for 21,479 hours0.00554 days 0.133 hours 7.919974e-4 weeks 1.822595e-4 months , or 40%. Other j

activities, such as maintenance, often were carried out concurrently with s

refueling. However, in general, it was not feasible to prorate the outage time to othcr than the reactor system and fuel elements. Maintenance or testing accounted for 4,499 hours0.00578 days 0.139 hours 8.250661e-4 weeks 1.898695e-4 months (8%), and 229 hours0.00265 days 0.0636 hours 3.786376e-4 weeks 8.71345e-5 months were the result of administrative decisions to shut down. Humboldt Bay was required to make i

seismic modifications and was shut down all year, thus accounting for 8,760 hours0.0088 days 0.211 hours 0.00126 weeks 2.8918e-4 months of the 9,413 hours0.00478 days 0.115 hours 6.828704e-4 weeks 1.571465e-4 months attributed to regulatory restriction.

j The reactor system accounted for 23,418 hours0.00484 days 0.116 hours 6.911376e-4 weeks 1.59049e-4 months , or 43% of the total.

Most of this time was for refueling; thus, fuel elements were the dominant component, accounting for 21,479 hours0.00554 days 0.133 hours 7.919974e-4 weeks 1.822595e-4 months , or 40% of the rotal. Oyster Creek required the most time for a refueling outage accounting 'or 2,004 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months .

In contrast, Vermont Yankee's refueling was accomplished in 661 hours0.00765 days 0.184 hours 0.00109 weeks 2.515105e-4 months .

The reactor coolant system accounted for 10,202 hours0.00234 days 0.0561 hours 3.339947e-4 weeks 7.6861e-5 months , or 19%, and the dominant component associated with this system was piping, accounting for 9,055 hours6.365741e-4 days 0.0153 hours 9.093915e-5 weeks 2.09275e-5 months , or 17% of the total. Humboldt Bay was the plant accounting for i

most of the outage hours listed under pipes and fittings. The plant was shut down all year (8,760 hours0.0088 days 0.211 hours 0.00126 weeks 2.8918e-4 months ) for scismic modifications.

4 The electric power system, steam and power system, and engineered safety features, each accounted for 1% of the total outage time.

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7 3.5.2 Pressurized-Water Reactors s

Forced Outages Forced outages accounted for 37% of the total PWR outage time, i.e.,

32,659 of 87,894 hours0.0103 days 0.248 hours 0.00148 weeks 3.40167e-4 months .

The largest portion of the forced outage time was the result of problems with the steam and power system which accounted for 9,410 hours0.00475 days 0.114 hours 6.779101e-4 weeks 1.56005e-4 months (11%). Turbines and heat exchangers were the components account-

.s ing for most of the outage hours attributed to the steam and power system.

The outage time attributed tc this system was widely distributed among the facilities. Oconee 1 accumulated the largest number of hours with 780 due to heat exchanger f ailures.

The reactor system accounted for 6,508 hours0.00588 days 0.141 hours 8.399471e-4 weeks 1.93294e-4 months (7%). Most of this time was due to the failure of fixed burnable poison rod coupling assemblies at Crystal River 3 (4,768 hours0.00889 days 0.213 hours 0.00127 weeks 2.92224e-4 months - 5%). Control rod drive seal problems at Palisades accounted for another 1,305 hours0.00353 days 0.0847 hours 5.042989e-4 weeks 1.160525e-4 months .

The Trojan plant accumulated 5,137 hours0.00159 days 0.0381 hours 2.265212e-4 weeks 5.21285e-5 months of forced outage time due to delay pending NRC license action on the seismic qualification of the control building structure. This outage accounted for 6% of the total outage time accumulated by all of the operating PWR plants.

The electric power system accounted for 4,856 hours0.00991 days 0.238 hours 0.00142 weeks 3.25708e-4 months - 4,038 hours4.398148e-4 days 0.0106 hours 6.283069e-5 weeks 1.4459e-5 months was due to a main transformer failure at Beaver Valley 1.

The reactor coolant system accounted for 4,386 hours0.00447 days 0.107 hours 6.382275e-4 weeks 1.46873e-4 months - 1,711 hours0.00823 days 0.198 hours 0.00118 weeks 2.705355e-4 months due to pump failures and 1,291 hrs due to valve failures.

Failures in the engineered safety features accounted for 1,379 hours0.00439 days 0.105 hours 6.266534e-4 weeks 1.442095e-4 months of forced outage, and various other systems ac-counted for the remaining 959 hours0.0111 days 0.266 hours 0.00159 weeks 3.648995e-4 months of forced outage time.

1 8

Equipment failure accounted for 25,882 hours0.0102 days 0.245 hours 0.00146 weeks 3.35601e-4 months of the 32,659 hours0.00763 days 0.183 hours 0.00109 weeks 2.507495e-4 months of forced outage time. The 5,137 hours0.00159 days 0.0381 hours 2.265212e-4 weeks 5.21285e-5 months assigned to regulatory restriction was the time accumulated by Trojan for seismic qualification of the control building. Opera-tional errors accounted for 1,084 hours9.722222e-4 days 0.0233 hours 1.388889e-4 weeks 3.1962e-5 months and the remaining 556 hours0.00644 days 0.154 hours 9.193122e-4 weeks 2.11558e-4 months were due to various reasons.

Scheduled Outages Scheduled outages in PRRs totalled 55,235 hours0.00272 days 0.0653 hours 3.885582e-4 weeks 8.94175e-5 months or 63% of the total PRR outage time. The reactor system accounted for 42,101 hours0.00117 days 0.0281 hours 1.669974e-4 weeks 3.84305e-5 months , of which 39,589 hours0.00682 days 0.164 hours 9.738757e-4 weeks 2.241145e-4 months was for refueling. The steam and power system accounted for 7,883 hours0.0102 days 0.245 hours 0.00146 weeks 3.359815e-4 months , with 5,114 hours0.00132 days 0.0317 hours 1.884921e-4 weeks 4.3377e-5 months for heat exchangers, and 1,677 hours0.00784 days 0.188 hours 0.00112 weeks 2.575985e-4 months for turbines. Pumps required 2,022 hours2.546296e-4 days 0.00611 hours 3.637566e-5 weeks 8.371e-6 months di the 2,636 hours0.00736 days 0.177 hours 0.00105 weeks 2.41998e-4 months assigned to engineered safety features.

The reactor coolant system accounted for 2,053 hours6.134259e-4 days 0.0147 hours 8.763227e-5 weeks 2.01665e-5 months ,and 562 hours0.0065 days 0.156 hours 9.292328e-4 weeks 2.13841e-4 months were accu-mulated by various other systems.

Maintenance or testing accounted for 18% of the total outage time (15,694 hours0.00803 days 0.193 hours 0.00115 weeks 2.64067e-4 months ). The remaining 45 hours5.208333e-4 days 0.0125 hours 7.440476e-5 weeks 1.71225e-5 months was due to administrative decisions and the 1

need for operator training and licensing.

3.5.3 Observations on BWR and PRR Outages Forced Outages Twenty-five BWR plants experienced 18,554 hours0.00641 days 0.154 hours 9.160053e-4 weeks 2.10797e-4 months of forced outage - an overall average of 742 hours0.00859 days 0.206 hours 0.00123 weeks 2.82331e-4 months per plant. Forty PRR plants experienced 32,659 i

hours of forced outage - an overall average of 816 hours0.00944 days 0.227 hours 0.00135 weeks 3.10488e-4 months per plant.

Additional insight into the outages at BWRs and PWRs may be obtained by reviewing the data in Table 3-6 which compares the forced outage time percentage i

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9 and the average number of hours per plant for the listed component, which con-tributed 1% or more of the total outage time.

The dominant component contributing to BWR forced outage time was piping, accounting for 238 hours0.00275 days 0.0661 hours 3.935185e-4 weeks 9.0559e-5 months per plant.

This was followed closely by valves, with 71 hours8.217593e-4 days 0.0197 hours 1.173942e-4 weeks 2.70155e-5 months per plant, and pumps with 64 hours7.407407e-4 days 0.0178 hours 1.058201e-4 weeks 2.4352e-5 months per plant. At PWRs, control rods accounted for 119 hours0.00138 days 0.0331 hours 1.967593e-4 weeks 4.52795e-5 months per plant, transformers accounted for 101 hours0.00117 days 0.0281 hours 1.669974e-4 weeks 3.84305e-5 months per plant, and turbines accounted for 87 hours0.00101 days 0.0242 hours 1.438492e-4 weeks 3.31035e-5 months per plant.

Scheduled Outages The 25 BWRs had 35,620 hours0.00718 days 0.172 hours 0.00103 weeks 2.3591e-4 months of scheduled outage time for an average of 1,425 hours0.00492 days 0.118 hours 7.027116e-4 weeks 1.617125e-4 months per plant. The 40 PWRs accumulated 55,235 hours0.00272 days 0.0653 hours 3.885582e-4 weeks 8.94175e-5 months for an average of 1381 hours0.016 days 0.384 hours 0.00228 weeks 5.254705e-4 months per plant.

The scheduled outages in the two types of reactors are compared in Table 3-7 on the basis of outage time percentage and average number of hours per plant. The compa'rison is made where g, listed component for either reactor type contributed 1% or more of the total outage time.

Fuel elements, the component involved in refuelings, commanded more outage time than the other components at both types of reactors. The average outage time due to fuel elements at PWRs was slightly greater than at BWRs, averaging about 131 hours0.00152 days 0.0364 hours 2.166005e-4 weeks 4.98455e-5 months longer.

Other than fuel elements, pipes and fittings were the components commanding the most scheduled outage time at BWRs, requiring about 362 hours0.00419 days 0.101 hours 5.98545e-4 weeks 1.37741e-4 months per plant.

At PWRs, heat exchangers ranked second behind fuel elements, requiring 128 hours0.00148 days 0.0356 hours 2.116402e-4 weeks 4.8704e-5 months per plant.

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10 3.5.4 Summary During 1978, the 25 operating BWRs experienced an average of 2,167 hours0.00193 days 0.0464 hours 2.761243e-4 weeks 6.35435e-5 months of outage time compared to an average of 2,186 hours0.00215 days 0.0517 hours 3.075397e-4 weeks 7.0773e-5 months for the 40 operating PWRs. The percentage of forced outage time at BWRs was 34% compared to 37%

at PWRs. The primary cause of forced outages at both BWRs and PWRs was equip-ment failures.

Refueling was the primary cause of scheduled outages at both BWRs and PWRs. Maintenance or testing also accounted for a large percentage of the scheduled outage time at both types of plants. Regulatory restrictions'on Humboldt Bay accounted for 17% of the total outage time accumulated by all BWRs.

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TABLE 3-la SUPet/JtY OF BWR POWER PLANT CUTAGES DURING 1978 i

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! Percent of year operational 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

,100 100 100 100 e

I Percent of year in comunercial operation 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

'100 100

'100 100 i

Scheduled outage during commercial

operation Hours 484 1264 2448 1910 391 505 768 1470 0 1446 994 2125 1049 8760 2318 866 906 ' 306 2004 1198 1199 831 76 1639 663 35620 Percent 5.5 14.4 27.9. 21.8 4.4 5.8 8.7 16.8 0

16.5 11.3 24.3 12.0 100.0 26.4 9.9 10.3 3.5 22.9 13.7 13.7 9.5 0.9 18.7 7.6 16.3l L

Torced outage during commercial operation Hours 1457 453 278 619 742 1234 25 929 512 1033 4862 319 1335 0 1014 197 212 121 245 261 147 6 19 367 96 1447 18554,

Percent 16.6 5.2 3.2 7.1 8.5 14.1 0.3 10.6 5.8 11.8 55.5 3.6 15.2 0

11.6 2.2 2.4 1.4 2.8 3.0 1.7 7.4 -

4.2 1.1 16.5 8.5 '.

Total outage

- during commercial I operation i

Hours 1941 1717 2726 2529 1133 1739 793 2399 512 2479 5856 2444 2384 8760 3332 1063 1116 427 2249 1459 1346 1480 443 1735 2110 54174 -

I Percent 22.1 19.6 31.1 28.9 12.9 19.9 9.0 27.4 5.8 28.3 66.8 27.9 27.2 100.0 38.0 12.1 12.7 4.9 25.7 16.7 15.4 16.9 5.1 19.8 24.1 24.7:

1

Unit availability 1 in commercial

! operation Perce.t 77.9 80.4 68.9 71.1 87.1 80.2 91.0 72.6 94.2 71.7 33.2 72.1 72.8 0

62.0 87.9 87.2 95.1 74.3 83.3 84.6 83.1 95.5 81.7 75.9 75.4' J

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TABLE 3-2 SUmfARY OF NUCLEAR PLANT OUTAGES BY TYPE FOR 1978 Forced Outages Scheduled Outages Total Outages Plant Type.

(number)

Number of Outage Duration Number of Outage Duration Number of 06tage Duration Events (hours)

Events (hours)

BWR Plants (25) 229 18,554 61 35,620 290 54,174 Average Per 9

742 2

1,425 12 2,167 BWR Plant 4

PWR Plants (40) 401 32,659 133 55,235 534 87,894

)

10 816 3

1,381 13 2,197 Average Per PWR Plant All Plants (65) 630 51,213 194 90,855 824 142,068 10 788 3

1,398 13 2,186 Average Per Plant Average Outage i

Duration Per 79 466 168 Plant C

j 1

TABLE 3-3a PROXIMATE CAUSE OF OUTACES Dt' RING 1978 Forced Outages Scheduled Outages Regulatory Training &

Equipment Maintenance Regulatory Operational E"E" Administrative Other Refuelin8 Administrative Totals Failure or Test Restrictions '

Error or Test Rest ric tions Licensing No. of 183 2

1 33 1

9 33 22 2

2 290 Eventa B'.1s 16.959 160 540 637 27 231 4.499 21.479 9.413 229 54.174 Hours of Outags No. of 327 3

1 55 2

13 99 30 3

1 534 Events Pbis

. p A

25.882 270 5.137 9 084 28 t 258 15.694 39.496 39 6

87.894 Hours of 4

outage N. _ )

510 5

2 88 3

22 134 52 2

3 3

824 No. of Events All Plants 62

<1

1 11

<1 3

16 6

<1

<1 100 Percent of Total 42.841 430 5.677

' 1.72 2 ;;

55 489 20.193 60,975 9.413 19 235 142.068 Total out-age Houra All P1snts

,g

,g 4

1

<1

<1 14 43 7

<1

<1 100 Percent of Total w

.m_

~,, _

= _..

TABLE 3-3b RATIO OF OUTAGE HOURS TO 100 OPERATION L HOURS Equipment Maintenance Regulatory Operational "I"I"8 Administrative Other Totals Refueling Failure or Test Restrictions Error Licensing I

HW 9.8 7.7 2.1 4.5 0.3 0.1 O.1'

'24.7 PWR 11.5 7.6 4.7 1.5 0.3 0.1 25.7*

Differs from total outage percent given in Table 3-lb due to rounding off of the values.

i 6

r

e e

8 e

TABLE 3-4 SOILINC HATER BEACTOR FuzY OUTACES IN 1978*

OUTAGE AS5OCIATES Ass 0CIATED PtANTS CL Tect 5T STIJE CUMF0erEST AFFECTED CAUSE TTFE l

DUANE Alt 90t.0-6,752 pgygg g ggy.ggggg OTRLA5-201 REACTOR 4.951h 92 L.95 9h 91 Co0LANT Esobh1 FLAar 1-239/DELSDEN 2-249

, y gg QUAD CITIES 1-260/0 Tut.R5-10 39 1.76 7h 31 1.767%

T S t an LAC ROM E 4

gpg h_6cm Sat %wira 1 g

1,600h it Hon v a a tos;5 1

60 th 160 1 40 ]n V Aa lon 1

9.1 %$h 1 71 m'J eg W A,p f 015_

1,._; q wash ('S 3

IQif!Pitt%f 70 %

GEnf RAYe*5

% /m V Ap lot's 1,

F41LLRE gg I

\\

l

I '.'1" m,

Foaca 4< m TL RB IND 1

9.eg W AD 1005 Svh FIFES 6 tALVES t ihm b 4h ioW5 g

2.56th St ;;lg W Ap lcq t

1g w At l00 5 "I

I#

ENGINEERED 5AFETT

,'I--1 4 Zh 4-b4

'.2-FEAft'R ES 54'm 451 APPLMASLT 1

4oh Def f DEN 1 j *t 2.6 73h 41 'se )h tan tot s em vaplotis it gi.

T. Assm 4

. vi. <* tm, i-6,um

.u-,

i;

,L,cT,,,,,

abh ELECT UW.f"Ci5*i J!,*S=h W As f 005 1*

1. 616h 31 + }4g V 4A ! C43

)). 30%

V Ap ]Otg It CONTRul. 500 DRhi-1281/

816 500 FT-1251/

ggggg OTHEE-12 7 OTuras-325 1.40Ph 31

1. 60=h 3t i.4onw 31 AADhastE FIFth-996 nAICH 1-toe /

16,9s*%

11'l 1.879%

71 1 079%

PTMf Rt-P )

71,Le795 eTMet-91 71

) 'a OPf RA?les sL l*4Wi 2

t DE p' 57 6 ;:T it %

1 I6C-e let f LA)S-12 11 me sh W ARIn$

l'

.vw h= 9h 16C lt 9=%

19.3344 362 :l eh W A t ! 0L 1 elt 21.h

% ARIOL S e l* 21.h v4R I0t s a lt

-1%

Cief 1

015TER CREEK

?.0^4%

41 FITZFATRICE 1.976%

41 BRWM5 FEtat 3

1. Fa th 3t uCRos5

1. 75 th 31 DRE5DEJB 1 a i

,1. 6 79h it DRE5 DEN 3 N

1EFLfLIM I.600h 5'1 ELDENTS QU4D CITIE5 2 REACTOR 1.31 %

taca5 FLaar 1 1.2%44

?

SAWN 5 FLAAT 2 1.77 Fh 2!

FEALM 80TTOM )

1.19 %

?

MAICh 1 1.00 %

21 DLA&E AAbdLD

'S**

?

ScitDtTLD FLACH 50710'12 OUTAGE 5 016h N!LL510h1 1 466h F*

Muh!!LELLO l

.rt o

on.

it 21.479%

60t c614 vi fytW A.91E 1*

?!.6 7*h 6S' g

FIFE 5 6 F Lt1&N5 84Wh5 FLARY 2 4

kre

t L;m

.t 2 3.418th 6 )!

? ?*5 CRrPvt-.a*!0THL4-253 11 71 % 81G Rx K FI-sa6/CTMtes-;M 11 SECL'LATCtf B15:RICTIC4 tiet90 LIT Bat.stes go, SEISMIC puttFICAT10h53 EUwtoLDT BAT-8760 Ff FES 4 FITT11er.5 FIACM DOTTIwt 2-242 RuCTOR CTMEB5-5 3 CM i

9.411*

1 71 9,05%

1 71 9.03 %

171 na t yrg mAnt g 6 51h Pt*PS 1 A r?% LAs A4559-% ?!0THe nS a l:

ce I"* 3 "4

I T**

IT*

II IESIl%

I'I * *'.*5 I f'l.5 FILCfWM'A[MTICLii 3I 71*ICI" lo t i

t T1 LLECT COMEC1'e s e.

f t.F CT W k 68 h

$YFMt 6 PW8 e 1 641h 4TII- % )?/oThi t-L.6 t pp h Yg!MS It iE* E 'N SAfif f F!Aftptt

% f)

5ma & 5-49 )/vi e t ts-il 1 p h*h

'4819 5 1;

A; -i. i s: nA t i. t

.it 44*%

0:

1$. 4 2%

tan in vi.n i%$

11 v An te

,,i iv yh j d5i s

, ti" (%

e$*1 SLGAE Owtages teteled $6,I)4 bessee (20G1).

- A dgWhM n

e

e e

TABLE )=$

PRES $U112ED bATER Rihlos FLANT GUTEES IN 1978*

OL'T ACS AS50C 1ATES A150t & Aff3 PLA!*T5 OVTACE T1 PE STSTLM CtstFokEh!

Af f tCTED CAU5E Aasmas a-so6 C,A,LM,,8,T C11f fs 1 34,1 nas NEs

,, ista,3 g,gg I

If STEMI 33, 3.jd,h g.,,,

Ano stat ucxAREas 5

Zy99h it 1 40 %

V AR t t# 5-444 T1, 6

4 32n w e,L. V9 5 4

411%

V 4810L,)

);17 7h 140- 541/ t t F# - 5e=

t 12?h

% Ap lfL>

mn ote v-4uires-4i2 lum

$ An te 9.419%

111 U =* u n-22 )!vaa ldt5-bl lt 4 7*h WAA LWS CUNTBob RODS CRISTAL RIVER 3 I#I M BEACTCG O AILL AR 6 ?68%

$1 4,,,4 *h it CusinoL aua salvts-1720 AdDh PAdijpf s mit fe8CER e.5394 71 I. F40h Caf sas-20

?! 43%

n An tot s alt GkTEE5 (CONTROL LDING) 3.13'h at 5.117h 61 5.1 ) Th St SEAVER VALLET 1-),432 TAANSFtNtfIERJ ELECTRIC PCWEg UINL95-606 4.0 48%

set 6,0 38h ett

. 9%=

.st a sh v A = t ot s it a n=

v sn i m :.

It

s.ssrs rit EALAM l-b.' * : utohLE 2-366 (L

p W HO 6

)

kl a s-912 v

'1%

F f P F -*)2/ Af C19-29 5 14 %

vaelw5 1

4. l*9h

$1 ***Q M;12 71v4W ICt %-64{_ip* *h

% 4512 L'5 1

1 3?9h Ffqp ES 71 33% V AB E%-2 dfp.1mt e-219 2

'*0 %

tatW 5 Q)%

6*

E%54Elkl2 5 apt.!T

?49 ELEC T4tf AL MULTM4

} * [6,Q*@TG'.f 2- ? H W TWI R 5-1 )O 1

1,, e A 6%

rPt aailm4L f **o*

It 12,6 %4h

)?1 5,549 4 6C-)* vdTmF R-)** IFwuh wan tor.t5 1 434%

V 4 p f.it's u.h.&....t#fSl.G S D E

FALISADES

?. 4"h 31 INDIAN FCIDT 2 2.414h It kC8thwat 2 1.94 ?h 21 INDIA 4 Polhf )

113h 21 Cuun &

.L 948h 21 2

TROJAA 1.8005 ft CALVERT CL&FF51 1.96 1%

23 FT. CALH00h 1 1.716%

21 210m 2 1.4Mh 21

51. LLC 111 FliEL ELI2tl.NTS

,,,,tg g,,, g REACTOR 1.4 72h 21 Cikh4

!. 3f ?h 21 AXnAhhA1 &

1. )**h 21 OCobEL 1 IJ]h 2T scufDLUS Jt') ?h 5*9 f*SMF i t

OUTEES 1.4.11h Ti'#F E T Ft'l

f 4 2

1. arn riev i i

J,.g,.=Jh

!1,8s51 PelKT 1 1

julf5 N0' f f 2

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9 f.% 7%

MAlhL V A% EE 2

ly m C AL%tRTAirF5 2 pin 5tft#T I 1

ann omvri 2

8ID

' EM.h3 E E

A 7 34 RAAO"> t tt0

>++m Pt % M SoTTP 2 3

43%

FDAL811 ISM %d J9.486%

4)*

M4 e FR I SL 2-460

.1 FLAiN set l~1Lb4 4 1g.5 99h 4)! lee * *h I.AIII C"""

21 1

21 2. t un

_N HN-3 3 h ( W 8-19 li du%h ( kas v t - 31 ?> m > Lp - 19 it EW 7.10th ett MILL &TWE I WI TupkEf FT *-e2=#sr4Au 2-47) i l

ITEAM UMIII 1AN ONO#RE l-4Tircota 2-185 I'IAlhTEWS AND ST. LUC 1E 1-J28/0TMERS-70)

CE T15T M144 61 1.04 7h eet power

a

--EST i i;

tunsants

,1 &f fh

}! { }!9 B ARyf1 1-684#0Tmf R%-243 l1 2em

t i.a n 2h mvE s-u4/eTar a-"'

a t :. : t ii-on 2-n*<otam-)u it E=.inrEenn sarin emFs iam n me mtn 1 i!.

rtATumEs 2.12 rh 2*

i1 s

o, 7.4.%%

31 n i sh Smrs h 5Sn/ 0TWi t -66 11 alen V At tors 11 ELAC114 0001Ahi PLNFh-4 MO EsAWi$ SLSSL 1-016s 163 Ff A-492 78 45 21 ?.91 %

V A.t!**t* *91 21 7/jl OTFY pM*O 21_

19.996h 19'l e tt w2 vo tots it e voiets it 3:h

= As tws it ce Tw-wram..

51.21p ren ei

.i.4 u, n w. u00u.

1 i

i4 d !

=

TABLE 3-6 COMPONENTS INVOLVED IN FORCED OUTAGES BWR PWR System Component

(%)

(Avg. hrs.)

(%)

(Avg. hrs.)

Steam & Power Generators 1

28 Turbines 1

20 4

87 Instrumentation 1

24 3

60-Heat Exchangers Valves 1

22 Reactor Coolant Piping 9

198 Valves 3

71 1

32 Pumps 3

64 2

43 Instrumentation 1

16 Engineered Safety Shock Absorbers 2

42 ea ures Electrical Conductors 1

22 Electric Power Transformers 1

21 4

101 Electrical Conductors 1

18 Reactor Control Rods 5

119 Control Rod Drives 3

51 2

43 Radwaste Piping 40 Instrumentation

. Instrumentation 1

25

& Controls Other Control Building 6

128 s

t

/

^.

.o TABLE 3-7 COMPONENTS INVOLVED IN SCllEDULED OUTAGES 1

BWR PWR System Component

(%)

-(Avg. hrs.)

(%)

(Avg. hrs.)

Reactor Fuel Elements 40 859 45 990 1

Control Rods 2

54 Pipes, Fittings 2

48

{

Reactor Coolant Pipes, Fittings 17 362 Pumps 1

26 2

34 Engineered Safety Pumps 2

51 Features Steam and Power.

Heat Exchangers 1

21 6

128 j

Turbines 2

42 Electric Power Elect. Conductors 1

29 h

l

)

e-

n p

N u

Pl d a a r TL LO Vi$ &&

C}Adhl_ER8@

3 w

we

-ww=w.e--se e

e

~

l 1

,Ww

+-

eem-tw-de e

%=

a-m e

,,-.,,m.,

=_

1

'MW'

?s a k h

A' e i

's ]

'~

NUREGM83 k/Mgp1EMI kb

\\

i l

t, l

I NUCLEAR POWER PLANT I

OPERATING EXPERIENCE - 1977

(

I

.l j

(

Annual Report I

I 1')

M. R. Beebe I.

uf d

4 Manuscript Completed: January 1979 Dste Published: February 1979 Office of Management and Program Analysis U. S. Nuclear Regulatory Commission Washington, D.C. 20555

.i a

9 e

Y 1

h 3.0 PLANT OUTAGES 3.1 Introduction g

}

A review of the plant outages or shutdowns that occurred during 1977

)

provides a means of assessing the nature, number, and extent of the

)

operating problems experienced at nuclear power plants, as well as the principal systems and components involved.

Most of the data were obtained from the data reported by the licensee for the NRC's monthly

" Operating Units Status Report", although in some instances it was necessary to check information in the licensee's periodic operating i

reports.

In a few cases, outage type was classified differently than reported by the licensee.

For example, where appropriate and sufficient information was available, major outages were subdivided to reflect more accurately the true nature of the work performed during the i

outage.

Also, the forced extension of a scheduled outage

was generally reclassified by the NRC staff as a forced outage.* In a few cases, work that had been scheduled for later in the year was rescheduled so it could be performed during an unexpected forced outage.

These cases were classified as scheduled outages.

Refueling of the reactor is also classified as a scheduled outage.

Data sheets for all the plants considered are contained in Appendix B.

In reviewing the outage data, it should be noted t' at there are signi-ficant differences in nuclear plant designs, even Latween plants of a given type.

Therefore, care should be used in interpreting the data.

3.2 Plant Outage Statistics There were 892 outages requiring 142,175 hours0.00203 days 0.0486 hours 2.893519e-4 weeks 6.65875e-5 months of plant downtime reportcd by the 61 nuclear power plants which were in commercial operation during 1977.

The average total outage time during commercial operation was 26.9% of the year; the average forced outage time was 6.7%; and the average scheulded outage time was 20.2%.

The average total unit availability for the 61 plants, considering only the period when they were in commercial operation, was 73.5%.**

3.3 Types of Outages Identification of types and causes of major outages for each plant in commercial operation is contained in Tables 3-la and 3-lb.

To provide

See Glossary - Appendix A.

- The availability plus the percent total outage time exceeds 100%

because, by definition, the availability factor includes " unit reserve shutdown hours" which are also counted in the " total outage time".

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I 0I

{

an overview of plant outages, these tables list plant availability, j

percent of scheduled, forced, and total outages with the outage d

duration, and the major systems and components causing outages lasting i

longer than five days.

As shown in these tables, these plants experienced 44 major outages for refueling.

There were 31 major outages involving the reactor coolant system, and they affected 20 of the 61 operating j

plants.

There were 24 major outages attributable to steam generator problems at PWRs.

s j

Table 3-2 summarizes the outages by type (i.e., scheduled or forced) and indicates the relative impact on plant operations.

During 1977 (and s

considering all of the reported outage data), the average number of j

forced outages for each nuclear plant was 11, with each outage averaging i

52 hours6.018519e-4 days 0.0144 hours 8.597884e-5 weeks 1.9786e-5 months in duration.

The average number of scheduled outages was three per plant, with each averaging 587 hours0.00679 days 0.163 hours 9.705688e-4 weeks 2.233535e-4 months in duration, k

3.4 Proximate Cause of Plant Outages Outage events and proximate causes are summarized in Table 3-3.

Outage cause was selected by the NRC staff to be in one of the following eight categories:

(1) refueling (scheduled), (2) equipment failure (forced),

(3) maintenance or test (primarily scheduled), (4) operational error (forced), (5) regulatory restriction (forced and scheduled), (6) adminis-trative (forced and scheduled), (7) training and licensing (scheduled),

and (8) other.

The operational error category includes any plant personnel errors which caused a forced o dage.

Scheduled refuelings required the most outage time of all causes with cE,657 hours0.0076 days 0.183 hours 0.00109 weeks 2.499885e-4 months (47%).

Equipment failures (forced) accounted for 30,545 hours0.00631 days 0.151 hours 9.011243e-4 weeks 2.073725e-4 months or 21% of all outage time.

Scheduled maintenance or testing consumed 28,618 hours0.00715 days 0.172 hours 0.00102 weeks 2.35149e-4 months - 20%.

Regulatory restrictions

accounted for another 10,466 hours0.00539 days 0.129 hours 7.705026e-4 weeks 1.77313e-4 months (7%) of scheduled outage time. Humboldt Bay accounted for 8,760 hours0.0088 days 0.211 hours 0.00126 weeks 2.8918e-4 months of the outage time due to regulatory i

, restrictions. The plant was shut down all year for seismic modification -

continuing a shutdown which accounted for 1,344 hours0.00398 days 0.0956 hours 5.687831e-4 weeks 1.30892e-4 months in 1976.

Although the number of plants considered in this review increased from 55 in 1976 to 61 in 1977 (11%), there was a decrease in total outage hours of 5,967 hours0.0112 days 0.269 hours 0.0016 weeks 3.679435e-4 months (4%).

Equipment failures (forced) showed a decline of 13,341 hours0.00395 days 0.0947 hours 5.638227e-4 weeks 1.297505e-4 months (30%), while refueling accounted for an increase of 17,173 hours0.002 days 0.0481 hours 2.86045e-4 weeks 6.58265e-5 months (35%).

The most dramatic change from 1976 to 1977 was the decrease in outage hours at PWRs due to equipment failure (forced) -

the decrease was 13,554 hours0.00641 days 0.154 hours 9.160053e-4 weeks 2.10797e-4 months (43%), probably reflecting improved preventive maintenance programs.

See Glossary - Appendix A.

3-5

TABLE 3-2 sum!ARY OF NUCLEAR PLANT OUTAGES BY TYPE FOR 1977 Force'd Outages Scheduled Outages Total Outages Plant Type (number)

Number of Outage Duration Number of Outage Duration Nwmber of Outage Duration Events (hours)

Events (hours)

I LWR Plants (25) 261 15,067 76 54,568 337 69,635 A*[^E 10 603 3

2,183 13 2,785 g

PWR Plants (36) 421 19,671 134 52,869 555 72,540 Y' ^" ##8 12 546 4

1,469 15 2,015 os PRR Plant All Plants (61) 682 34,738 210 107,437 892 142,175 Ave [a 11 569 3

1,761 15 2,331 n

i Average Outage Duration Per 52 587 155 I

Plant r

I

-e l

4w*

c W4+4M

' +...

{

- e m - s-

. mew.

_.,g,.

gg.:

LwQ,4gy TAKE 3-3 l' A011 MAT, CAUil CF otT Ai,,15 LLN1% 1477 5sheduled Outages Forced Outages Regulatery ral.i.g &

Equipme.t Ma i.t e.a.c e Regulatory Operatio.al Adel.istrati.e Ot he r Re t oeling Admi.is t ra t i.e Othe r Failure or Test Restrictio.s Frror or Test Res t r ic t io.s Licensing 795 3

4 31 3

15 S6 18 2

2 9

3 351 No. of E.e.t s B.'R s 12,3d8 461 372 699 436 614 11,163 32,940 8,844 til 1.419 91 69,635 hours0.00735 days 0.176 hours 0.00105 weeks 2.416175e-4 months of Outage

{

e 34 6 1

SO 25 101 26 2

2 1

556 i.

No. of E.ent s l

PWlts 18,157 378 714 422 17.4 %

31,717 1,622 31 64 72.540 N

No. of

$$g 3

g3 3

40 159 44 4

g gg y

9gy Eve.ts i

All

{

Flants Percent of 61 41

<1 9

1 4

16 5

<1

<1 1

<1 100 Total

[ '

30,545 461 730 1,513 63) 1,0 30 28,61B 66,657 10,466 162 1.463 91 142,175 8"

All ela.ts (a

21

<1

1 1

1

1 20 47 7

<1 1

41 100 l

Perce.t of l

Total l (g.u i t

.T., s..

.,s

.1,,.

.i i.st i, y

Ts.s.

.ta r.u.o s m i.isi.e.,ts. t.t.i..t...s to _r. am.r.t.s aso i. T.61.1,r.n.m m

..t... o,Ts.,. is o.e,a.aiti 1

,e,.a.

.t,er t s. re...e4 14 44.i.t i 1 s< s.2.1 4

....t s,or re s,

,ro.

..r o, o..: s 3-2.

t s. ra... o m. o.t a....d

....t..,

m,,.,,

.,m, m o.ta...

(C h C.[,2. 1

(-M)

I C'~_J i

c-r-

C'=

1

1 t

3.5 Systems and Components Associated With Plant Outages A graphic representation of plant outages is shown in Tables 3-4 and 3-5.

These tables classify outages by type, and identify system, component, plant, and cause.

Outage duration in hours and the p'ercent of the total outage time is listed for major groupings.

The size of each box is proportional to the hours involved to the nearest 1%.

The system and component classifications used in this report are listed in Appendix 3.

Because of the fundamental differences between BWRs and PWRs, they are discussed separately.

1 3.5.1 Boiling-Water Reactors Forced Outages Two hundred sixty-one forced outages accounted for 22% of the total BWR outage time in 1977 - 15,067 of 69,635 hours0.00735 days 0.176 hours 0.00105 weeks 2.416175e-4 months .

As indicated in Table 3-4, the steam and power system accounted for nearly half of the forced outage time with 6,753 hours0.00872 days 0.209 hours 0.00125 weeks 2.865165e-4 months , or 10% of the total.

The reactor coolant system accounted for 3,675 hours0.00781 days 0.188 hours 0.00112 weeks 2.568375e-4 months (5%), and the engineered safety features accounted for 1,815 hours0.00943 days 0.226 hours 0.00135 weeks 3.101075e-4 months (3%).

The remaining 4% of the forced outage time was accounted for by various systems.

The major components involved were valves (2,833 hours0.00964 days 0.231 hours 0.00138 weeks 3.169565e-4 months ) and the main generators (2,263 hours0.00304 days 0.0731 hours 4.348545e-4 weeks 1.000715e-4 months , or 3% of the total) with Brunswick 1 accounting for 2,033 of the 2,263 hours0.00304 days 0.0731 hours 4.348545e-4 weeks 1.000715e-4 months .

Turbines also accounted for about 3%

of the total outage time, requiring 1,926 hours0.0107 days 0.257 hours 0.00153 weeks 3.52343e-4 months .

Various other components accounted for the remaining time.

Scheduled Outages Scheduled outages in EWRs total 54,568 hours0.00657 days 0.158 hours 9.391534e-4 weeks 2.16124e-4 months , or 78% of the total BWR outage time.

Refuelings accounted for 32,940 hours0.0109 days 0.261 hours 0.00155 weeks 3.5767e-4 months , or 47%.

Other activities, such as maintenance, often were carried out concurrently with refueling. However, in general, it was not feasible to prorate the outage time to other than the reactor system and fuel elements.

Maintenance or testing accounted for 11,163 hours0.00189 days 0.0453 hours 2.695106e-4 weeks 6.20215e-5 months (16%), and regulatory restrictions accounted for 8,844 hours0.00977 days 0.234 hours 0.0014 weeks 3.21142e-4 months (13%). Humboldt Bay was required to make seismic modifications and was shut down all year, thus accounting for 8,760 hours0.0088 days 0.211 hours 0.00126 weeks 2.8918e-4 months of the 8,844 hours0.00977 days 0.234 hours 0.0014 weeks 3.21142e-4 months attributed to regulatory restriction.

There were 1,419 hours0.00485 days 0.116 hours 6.92791e-4 weeks 1.594295e-4 months (2%) attributed to administrative decisions, and these were primarily the result of demand for power.

i i

l 3-8 L

F I

TABLE l-4 BOILING WATER REACTOR FtANT UtlTAGES," 1977 I

i A55MI ATED ASSOCI ATED PLANTS OUTACI l

4 T A.g p rt

$Y$t DI CmFUWENTS AFFFCTED

( Ali1E

,,I stuu tra 1-201);

1 CENERATORS OTHLB h-210 I

g y,,

2.26 %

124 1 %

31

*d saias nRn 2 Q

Tt R8 t uFs i 1am, 21~

1,9 26h g b,6 "

P"

VAR s ot s it p

464h hP AT t KCMAN.F R5 l { ___ h D9 F SDFM l- {% OTnf RS-2 76 It P !!Lp ! 1 11 HAf t H33h'9 609%

DFfil ki t Al. I Z LR$

It Wh

["

ikFRS 2e7 1(

tyEIPMENT 5)Jh V Alb L 5 11.Th o f s >h tot a in v As t ot s it 7615 Mil.l stone 1-2 )); uTurRs-s2s it FA s tt:E j;

,,g uArtu 1-566; Femu not. 2-109; 1,

' l "' Li VALW3 FERRT 3-2861 1,

a i 81$h t

l# e14h oTHP s 5-4 F3 11 C MT 4

.e O

{

371h r1MPS 11-n ?)b BRt'N541J K 1-)1&oihtp5 495 11 I

1,6 M n St %*n vaa r*s it wh v AR iws

t i

5Af ETT FIATURES

'WOh (0%T, Fl%FTRAf tons 11 +Mh bp F sN M 1

~

1 th61M ERFD

..61h V ALv t 3

?(3.4Rh VARM5 t.

i

{

7h V A R_lir S

,1 2,,181 %

14t 4

'Al%

31 444%

V AR i ots it,

'f5h I 4C J1

'4 5n I br - 4 4egyT e p -2 59 11,]."Th VAhleni

,t 19% UFFRA!!o%Al I Rkek 11 I

N

'9]5 t"*D 5 'b4

11. '9 th L >t>w 11 79 2h t'af sDEalT4 24; OTHF R S-44 i t_.

1.h V AD l' o s 11 t ljM 7h 21 ! 29%

21 1,2 9 7h 21_

9'

. [}

l% _

h j

b LAC RoS S E LS?!h Et,

s BatM5 Ff R8V 1 2

41 p,619*:

J a

t OV5TER (RFEK 1 k&Uh I

4T f

l FITZPATRICE j

2211h

'I 8'

SIC RiAK PolNT le 2,24 i h it FFM M BOTTi91 2 gg 7,

R I. F1' El. I %C R EACTOR

'1#969h I.~

BRCR 5b l C E I DRESDFM 2 1,75th IT 1 509h 71 fMg 1,49 th I_I HINE. MILE POINT gg 1, )A %h 11 SrstE3t'LLD QUAD CITIES 1

.Y U y t Ai,Ls

.h.6h 21

] 2 VFR7e mi T ANEF E gg q

'~,0 hh PtM M RailliM7 1

I

'9 3 %

~ i~th iM"1 I t" 12,9dh 471 r

f 12d40h 47tMS Lt!P t R Ik 13 74 %

441 4tM h O:W-M LiOTMt RS-2 4 11 +1%

V Aat ti4 5 11, MA LMTihANCE OR FPL5, FITTINGS TESTING REA' TOR ed Cooun M60h

121 fg N1 POI H

g 1 799h

, yt i t,t %,h 2

],

10d27h 141 1hMh FLAT H th)TTiH I

Ii

$1%

FPPS 11 41 %

BFL'MWILK 2-M l; OTMEN 5-125 LI j

576%

rq$

11 5 7hh PF ArH BoTTrzt 2 6 )

It 4

V ALVES-159; hm4 EE-)l6; Cn0PER-250; OThf t$-598

<21 Rf s T R tcile%

l_229h 191 s *Mh O'MFR-I T )

<21

% Rh PILCRIM 1 1,4 40h 71 SE15NIC f*m1FICATIONS ENGI NEF R ED FIFFS, FITT!NG5 912h PFM'N pott'el 4 it

-8 760h )

BN 2

11 Pt A5'% l( K'sk f pet 1 I t' Thhh SAFETT FLAftRES

>U j._Ah 1,8 6 4h 4 )?Oh et 50Ah

% AR!iCS 11 50hh MAf t M 1-10L oTHER S - 166 11 vtAD c tfits 1-e22; i,nt t 2-516 I 964 186h (LOW DDiawn) 21 9,944h lit not ArrttCAsLE 4

sTI.AM.nd P'M.R asih cF st pAtals it mn

.r: 2-629t.as2 it AnMinisinaf tvE

'mh S ARI M,5 it 1 419h 21 2,99 7h 41 e% HT EXCM- %1 Cria F D S-544 11 9

4 1 i ' _1a [5'U AE111_

+ 10 a #1 af "amY a-1i "9 h

it a 6 - u:

y aa i m

ilgg,h

%dd4Sh

?s{, g E

._................9.6,,h_..

[

R 1 d.c o GTW@W

~

o*

i Wmmum

7

,j r

j G

TABLE 3-S FRESSURIZED WATER REACTOR FLANT OllTAGES, 1977

-4 OCTAGE ASSOCIATED ASSOCIATED I

PLANTS OUTACE TTFE SY STDI COMPONENT l

AFFECTED CAUSE 7

SURAT 2 1_ylh 11 NEAT EXCRANGERS 1,046h OCONf_.E 1 11 39 %

OCOMEE 2

,1 STEAM Tf7h Ot'Oh EE )

.1 AND 5.44 Ah 7! 7 5 9h TROJ AN-254; OTHERS-505

.1 16 21 VALVES 51391h 3

h V AR [UU $

11 2 20Rh 31 Shh GENERAn t$

11 N1h ST, lEClf 1-11 N OTHERS-2 76 11 5'[1h P ' *tP S 11 521h W AR 10Ci lt 4 74h TL B R I MES 11.7eh V R IOL S i

%.,N T

.IN 492h errES, r1TTaic$

It.42h #EA6ER VALLET 1-22s; oTHERS-26*,t t

g

,g,g AW 10,615h 151 M4 7h 5HM KS-)96; OTHF R-4 91 11 16 7h BEAVFR VALLET l-)16; OTHE RS-5 71

.I

%Mh IN')! AN PolNT 2 It IN5pN 2-426 gTHERS-2 26_,j 1,52 h

?! hh R

aEACTom COOLANT 8 74h VALVES 12 9 74h INDI AN PT.

1-2%MT H E R S-6v4 1%

? 2,60_ h 4t f 6An F I P E-J54dTHE R-512 1{_ 46M V AR IUUS It 3

ENGlhtERED SAFETT

'

12h ACCUMULATORS 11 712h RollM50N 2 11 1f1%

FEATURFS m2! I,126h V ALVES-4skOTitE R-6 ) A 5 t_,,1,12 %

AREAh5AS 1-361; OTHERS-705 11 898h ELEgBICAL CONDCCTCRS 11 %%

COOK 1-42h CTHF_RS-479 11 g

g, 1,65 %

21 760h GEhERATi B5_-414 ; OTjip B-1.6 11 140h MILLS TONE 2-541 OTHI R S-179 lt l

t REACTOR t,15 7h 22 604h CWIR0L 8005-201; othER-Nd 11.6%

V AR IOUS

.1 19,15 7h 2'

i 612h ALR1LLARY PROCESS 11 012h W ALVE S-132; _eTHE R-2 80 12 e12h ST. LIKIE l-13}; OTHERS-280

,t 71.h orrRAT10hAL ERRnN I

19,6 71h 27%

511h IbC-414; OTHERS-li f it %11h 14C-299. OTFER-212 11 511h W AR IOLS

.,2 800h OTHt R-62 2; ret; R E S TR-3 78 TURKEY Po!NT 4 i

2,0 74h it i

ZION 1 2,064h it TANKEE ROWE 2,04 9h 11 CALVERT CLIFFS 1 2,000h g

ZDN 2 1.918h

)g RANCHO SECO I,872h I

FORT CALHOUN 1.645 h ARKAASAS 1 1 611h t

3 AUNEE Iph yt i

MAINE YANKEE RFACTOR FUEL ELDtENTS I'

II REFUELING 1.1%h THREE MILE ISLAc D 1 g

MITMM3 1,35 5h yg COOK 1 lys95 3

OCONEE 2 1,180h 2t 1.146h 23 1,132h PRAIRIE ISLAND 1 21 l

SCHEDULED If27h 21 l

3 MADDAM NECE I

g y%

yg 1pth OCo_hRE 1 11 Mh MILLSTONE 2 li 4h C ! %A 11 4 9 R5th PRAIRIE ISLAND 2 11 f70h

$_ttRT 2 11 i

74 2h POINT REACH 1 11 31 R95h 3461 55th SURRY l li

)),717h 4 61 14.172h 471 2 7 7h CR DM-24 h ; I6C-11 elt 217h VU1005 e lt SURRY I 1,415h 1,10ph MILLSTONE 2 SEAT EXCMANGERS 1,02 4h WPNFE 2 11 951h TLREEY PolNT 4 li N 2.h INDI AN POINT 2 li 199h OWNEE I 11 STMN

.6,217h 91 49 sh VARIX 5 g

AND 1,717h INDIAN MNT 3 MAINTENANCE gg MSINES IALEM I TES NG O'

21 7

TROJAN

21

.d.,

'A569h 61 12 VARIWS gg

'"' "3Y 1 VAtvES L46o%

1 M6)h 31 701h ST. LLCIE 1-175dHERS-328 1

13,75 7h 193 404h V AR IOUS 11 904h SEAVER VALLEY 1-284; OTHERS-520 t

ELECTRIC POWEA CENERATORS-2412; SAN OMOFRE l-2412; 2,505h 31 2,505h I~'I 31 2,505h H

31 REACTOR COOLANT d

915h SAN NE l-646; OMS-2H li 17,4M 24 h544h 21 629h FILTERS-44 ?i OTHEE-18 2 II 629h CALVFRT CLIFFS 2-125LOTHE RS _ lue,_d 11GUI.ATORT 66Ch LMKMWN 11I660h V1S EAiB lt %eAn CRTb7AL RIVER }-4 7 7; OTHERS-16) It 1,622h RESTR fCTIONS Il

_52.869h 731 2)lh ESRO: 16C-42 <11!2 31h VAAleUS

< d '211h VAAIOUS

< 1t 75h ADf!4-41; uPIR'TNG-ll 81!

M,1 E

E.... E.E.i.. n,seo h t. nocu, 3-10 y

p I

(

m

-w-m x

UM'

!~4 le ne reactor system accounted for 33,745 hours0.00862 days 0.207 hours 0.00123 weeks 2.834725e-4 months , or 48% of the total.

d inis was due to refueling; thus, fuel elements were the dominant J

mponent, accounting for 32,940 hours0.0109 days 0.261 hours 0.00155 weeks 3.5767e-4 months , r 47% of the total.

Lacrosse Q

nad the most outage time for fuel elements with 5,571 hours0.00661 days 0.159 hours 9.441138e-4 weeks 2.172655e-4 months .

During f

ne refueling, the fuel was found to be abnormally degraded, so the crm,=

"r j autage was extended for the remainder of the year to perform an evaluation and to take corrective action.

e p

y The reactor cool.;nt system accounted for 12,979 hours0.0113 days 0.272 hours 0.00162 weeks 3.725095e-4 months , or 19%, and the j

dominant componer t associated with this system was piping, accounting g

for 10,727 hours0.00841 days 0.202 hours 0.0012 weeks 2.766235e-4 months , or 15% of the total. Humboldt Bay was the plant 4

accounting for most of the outage hours listed under " pipes, fittings".

mg$it The plant was shut down all year (8,760 hours0.0088 days 0.211 hours 0.00126 weeks 2.8918e-4 months ) for seismic modifications.

D'Am 3

Engineered safety features accounted for 4,370 hours0.00428 days 0.103 hours 6.117725e-4 weeks 1.40785e-4 months , or 6%, and the steam and power system accounted for 2,982 hours0.0114 days 0.273 hours 0.00162 weeks 3.73651e-4 months , or 4% of the total.

The remaining 492 hours0.00569 days 0.137 hours 8.134921e-4 weeks 1.87206e-4 months were accumulated by various systems.

There were 3,864 hours0.01 days 0.24 hours 0.00143 weeks 3.28752e-4 months of outage time due to pipes and fittings of engineered safety features. The total number of scheduled outace hours expended for pipes and fittings was 14,591 hours0.00684 days 0.164 hours 9.771825e-4 weeks 2.248755e-4 months ('21% of the total outage hours).

3.5.2 Pressurized-Water Reactors Forced Outages Forced outages accounted for 27% of the total PWR outage time, i.e.,

19,671 of 72,540 hours0.00625 days 0.15 hours 8.928571e-4 weeks 2.0547e-4 months . The largest portion of the forced outage time was the result of problems with the steam and power system.

Surry 2 accumulated 1,973 hours0.0113 days 0.27 hours 0.00161 weeks 3.702265e-4 months as the result of steam generator tube leakage.

Problems with heat exchangers at other plants brought the total for this component to 5,440 hours0.00509 days 0.122 hours 7.275132e-4 weeks 1.6742e-4 months .

Valves in the steam and power system accounted for 2,208 hours0.00241 days 0.0578 hours 3.439153e-4 weeks 7.9144e-5 months of which 1,693 hours0.00802 days 0.193 hours 0.00115 weeks 2.636865e-4 months were accumulated at Beaver Valley 1.

The reactor coolant system accounted for 3,260 hours0.00301 days 0.0722 hours 4.298942e-4 weeks 9.893e-5 months of forced outage m

time, with 1,520 hours0.00602 days 0.144 hours 8.597884e-4 weeks 1.9786e-4 months due to pump failures.

The engineered safety features, electric power system, and reactor system accounted for most of the remaining forced outage hours.

Equipment failure accounted for 18,157 hours0.00182 days 0.0436 hours 2.595899e-4 weeks 5.97385e-5 months of the 19,671 hours0.00777 days 0.186 hours 0.00111 weeks 2.553155e-4 months of forced outage time.

Operational errors accounted for 714 hours0.00826 days 0.198 hours 0.00118 weeks 2.71677e-4 months , and rum

&c the remaining 800 hours0.00926 days 0.222 hours 0.00132 weeks 3.044e-4 months were due to various reasons. The number of hours due to equipment failure is a decrease of 13,554 hours0.00641 days 0.154 hours 9.160053e-4 weeks 2.10797e-4 months (43%)

from 1976 and probably is due to improved preventive maintenance programs.

There also was a significant decline from 1976 to 1977 in operational errors - from 2,599 hours0.00693 days 0.166 hours 9.9041e-4 weeks 2.279195e-4 months to 714 hours0.00826 days 0.198 hours 0.00118 weeks 2.71677e-4 months .

in 3-11

l i

I

!i Scheduled Outages ll

'i Scheduled outages in PWRs totalled 52,869 hours0.0101 days 0.241 hours 0.00144 weeks 3.306545e-4 months or 73% of the total PWR ji

{

t outage time.

The reactor system accounted for 34,172 hours0.00199 days 0.0478 hours 2.843915e-4 weeks 6.5446e-5 months , of. which y

33,717 hours0.0083 days 0.199 hours 0.00119 weeks 2.728185e-4 months was for refueling.

The steam and power system accounted for 13,757 hours0.00876 days 0.21 hours 0.00125 weeks 2.880385e-4 months , with 6,217 hours0.00251 days 0.0603 hours 3.587963e-4 weeks 8.25685e-5 months for steam genera' ors, 4,569 hours0.00659 days 0.158 hours 9.408069e-4 weeks 2.165045e-4 months for turbines, 2,163 hours0.00189 days 0.0453 hours 2.695106e-4 weeks 6.20215e-5 months for valves, and 808 hours0.00935 days 0.224 hours 0.00134 weeks 3.07444e-4 months for various other components. Generators required 2,412 hours0.00477 days 0.114 hours 6.812169e-4 weeks 1.56766e-4 months of 2,505 hours0.00584 days 0.14 hours 8.349868e-4 weeks 1.921525e-4 months accrued by the electric power system.

The reactor coolant system accounted for 1,544 hours0.0063 days 0.151 hours 8.994709e-4 weeks 2.06992e-4 months , and 891 hours0.0103 days 0.248 hours 0.00147 weeks 3.390255e-4 months were accumulated by various other systems.

t Maintenance or testing accounted for 24% of the total outage time (17,455 hours0.00527 days 0.126 hours 7.523148e-4 weeks 1.731275e-4 months ).

Regulatory restrictions accounted for 1,622 hours0.0072 days 0.173 hours 0.00103 weeks 2.36671e-4 months -

Surry 1 (800 hours0.00926 days 0.222 hours 0.00132 weeks 3.044e-4 months ) and Indian Point 2 (822 hours0.00951 days 0.228 hours 0.00136 weeks 3.12771e-4 months ) to perform steam

{

generator inspections.

The remaining 75 hours8.680556e-4 days 0.0208 hours 1.240079e-4 weeks 2.85375e-5 months was due to administrative j

decisions and the need for operator training and licensing.

}

4 3.5.3 Observations on BWR and PWR Outages l

l Forced Outages I

Twenty-five BWR plants er.perienced 15,067 hours7.75463e-4 days 0.0186 hours 1.107804e-4 weeks 2.54935e-5 months of forced outage -

i:

an overall average of 603 hours0.00698 days 0.168 hours 9.970238e-4 weeks 2.294415e-4 months per plant.

Thirty-six PWR plants

'f experienced 19,671 hours0.00777 days 0.186 hours 0.00111 weeks 2.553155e-4 months of forced outage - an overall average of 546 hours0.00632 days 0.152 hours 9.027778e-4 weeks 2.07753e-4 months per plant.

Additional insight into the outages at BWRs and PWRs maysbe obtained by reviewing the data in Table 3-6 which compares the outage time l

percentage and the average number of hours per plant for the listed component, which contributed 1% or more of the total outage time.

The dominant component contributing to BWR forced outage time was valves, accounting for 2,833 hours0.00964 days 0.231 hours 0.00138 weeks 3.169565e-4 months or 113 hours0.00131 days 0.0314 hours 1.868386e-4 weeks 4.29965e-5 months per plant.

This was followed closely by generators, with 2,263 hours0.00304 days 0.0731 hours 4.348545e-4 weeks 1.000715e-4 months or 91 hours0.00105 days 0.0253 hours 1.50463e-4 weeks 3.46255e-5 months per i

4 plant.

At PWRs, heat exchangers (primarily steam generators) accounted for 5,440 hours0.00509 days 0.122 hours 7.275132e-4 weeks 1.6742e-4 months or 151 hours0.00175 days 0.0419 hours 2.496693e-4 weeks 5.74555e-5 months per plant, valves accounted for 85 hours9.837963e-4 days 0.0236 hours 1.405423e-4 weeks 3.23425e-5 months per plant, and pumps accounted for 56 hours6.481481e-4 days 0.0156 hours 9.259259e-5 weeks 2.1308e-5 months per plant.

Scheduled Outages The 25 BWRs had 54,568 hours0.00657 days 0.158 hours 9.391534e-4 weeks 2.16124e-4 months of scheduled outage time for an average of 2,183 hours0.00212 days 0.0508 hours 3.025794e-4 weeks 6.96315e-5 months per plant.

The 36 PWRs accumulated 52,869 hours0.0101 days 0.241 hours 0.00144 weeks 3.306545e-4 months for an average of 1,4f9 hours per plant. The scheduled outages ir. the two types of reactors are compared in Table 3-7 on the basis of outage l

time percentage and average number of hours per plant.

The comparison

(

is made where a listed component for either reactor type contributed l

1% of more of the total outage time.

3-12 U

=

L 3i<

C*

PWR

?

ch k

ad 3

)

TABLE 3-6 COMPONENTS INVOLVED IN FORCED OUTAGES I

Crued for BWR PWR i

System Component

(%)

(Avg. hrs.)

(%)

(Avg. hrs.)

k

can & Power Generators 3

91 1

16 Pumps 1

14 Turbines 3

77 1

13 Itive "4

1 Piping 1

14

!j Heat Exchangers 1

27 7

151 l

Demineralizers 1

24 l

Valves 1

21 3

61 i

etactor Coolant Valves 3

73 1

24 Pumps 1

35 2

42

";ineered Safety Containment Penetrations 1

36 by Valves 1

19

~

{

Accumulators 1

20 lectric Power Electrical Cciaductors 1

25 i

ractor Control Rod Drives 1

21 t

)

of 1n l

3-13

TABLE 3-7 COMPONENTS INVOLVED IN SCHEDULED OUTAGES BWR PWR System Component

(%)

(Avg. hrs.)

(%)

(Avg. hrs.)

l Reactor Fuel Elements 47 1318 47 942 l

Reactor Coolant Pipes, Fittings 15 429 Pumps 1

33 1

25 Vessels 1

23 ' '

Engineered Safety Pipes, Fittings 6

155 Features Steam and Power Generators 1

27 Heat Fxchangers 9

173 l-Turbines 6

127 l

Valves 3

60 Electric Power Generators 3

70 o

?.,

)

il

L d

t h

i l

I

'n h

I 3-14

.i.

w r

t i

Fuel elements, the component involved in refuelings, commanded more outage time than the other components at both types of reactors.

WR The average outaae time at BWRs was greater than at PWRs, averaging about 376 hours0.00435 days 0.104 hours 6.216931e-4 weeks 1.43068e-4 months '(40%) longer.

vg. hrs.)

942 Other than fuel elements, pipes and fittings were the components commanding the most scheduled outage time at BWRs, requiring about 584 hours0.00676 days 0.162 hours 9.656085e-4 weeks 2.22212e-4 months per plant.

At PWRs, heat exchangers ranked second behind fuel elements, requiring 173 hours0.002 days 0.0481 hours 2.86045e-4 weeks 6.58265e-5 months per plant.

25 3.5.4 Summary During 1977, the 25 operating BWRs experienced an average of 2,785 hours0.00909 days 0.218 hours 0.0013 weeks 2.986925e-4 months of outage time compared to an average of 2,015 hours1.736111e-4 days 0.00417 hours 2.480159e-5 weeks 5.7075e-6 months for the 36 operating FWRs.

The percentage of forced outage time at BWRs was 22% compared to 27% at PWRs.

The primary cause of forced outages at both BWRs and PWRs was equipment failures.

173 Refueling was the primary cause of scheduled outages at both BWRs and

'27 PWRs.

Maintenance or testing also accounted for a large percentage 60 of the scheduled outage time at both types of plants.

l0 O

9 3-15

7-b Jh Sggg 0%

176/H W

?

M TN tt!n E W &c NUCLEAR POWER PLANT OPERATING EXPERIENCE 1976 Manuscript Completed: November 1977 Date Published: December 1977 i

[

Office of Management Information and Program Control U. S. Nuclear Regulatory Commissior l

Washington, D. C. 20555 s

1

%9 1

3.0 PLANT GUTAGES 3.1 Introduction Review of the plant outages or shutdowns that occurred during 1976 provides a means of assessing the nature, number and extent of the operating problems experienced at nuclear power plants, as well as the principal systems and components involved. Most of the data were obtained either trom the data reported by the licensee for the NRC's monthly " Operating Units Status Report,"

although in some instances it was necessary to check information in the licensee's periodic operating reports.

In some instances omissions or inconsis-tencies in the reported data necessitated checking with the licensee.

In a few cases, outage type was classified differently than reported by the licensee. Where appropriate and sufficient information was available, major outages were subdivided to reflect more accurately the true nature of the work performed during the outage.

The forced extension of a scheduled outage

was generally reclassified by the NRC staff as a forced outage.* In a few cases, work that had been scheduled for later in the year was rescheduled so it could be performed during an unexpected forced outage.

These cases were classified as scheduled outages.

Refueling of the reactor is classitied as a scheduled outage.

Data sheets for all the plants cond adered are contained in Appendix B.

In reviewing the outage data, it should be noted that there are significant dif ferences in nuclear plant designs, even between plants of a given type.

Therefore, care should be used in interpreting the data.

3.2 Plant Outage Statistics There were 881 outages requiring 148,142 hours0.00164 days 0.0394 hours 2.347884e-4 weeks 5.4031e-5 months of plant downtime reported by the 55 nuclear power plants which pere in comnercial operation during 1976.

The average total outage time during commercial operation was 31.9% of the year; the average torced outage time was 13.6%; and the average scheduled outage time was 13.3%.

The average total unit availability for the 55 plants, considering only the period when they were in commercial operation, was 68.63.

3.3 Types of Outages Identification of types and causes of major outages fcr each plant in commercial operation is contained in Tables 3-la and 3-lb.

To provide an overview of plant outages, these tables list plant availability, percent of scheduled, forced and total outages with duration, and the major systems and components causing outages lasting longer than five days. As shown in these tables, these plants experienced 39 major outages for refueling.

Ther'e were 44 major outages involving the reactor coolant system and thcr -'fected 27 of the 55 operating plants.

There were 30 major outages attributable to steam generator problems at PWRs.

See Glossary - Appendix A.

3-1

p-Table 3-la Su w ry of BA Pcwer Plant Outages During 19?*,

I 1

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ope r ational 100 100 100 100 100 100 100 100 10 100 100 100 l'10 100 200 109 109 1%

100 luu 100 lov 100 Percent of year Perrent of year operation 100 100 100 100 100 100 100 100 100 100 100 400 100 100 100 100 100 190 100 ILO 100 L O'J 100 in commercial Scheduled outage during cospercial Hsurs 4295 111 41 2148 1 R ')O 458 1674 1228 1618 1694 760 2tB9 6273 1678 660 144

e91 2375 1021

'299 2701 1135 1769 38)*7 vperation Percent 48.9 1.3 0.5

2.. 20.8 5.6 19.1 14.0

3. 4 19.3 s.7 21.0 48.6 16.8 7,5 1.6 19.) 27,0 11.7 26.2 30.8 15.2 29.2 16.0 i

t Forced ourage during commercial

}

Hm.r s 84 6499 6194 1720 324 897 446 322 296 798

'24 2116 3 12 624 e6 912 127 411 912 1153 V2 J%

239 25827 operation Percent 1.0 73.9 70.5 19.6 3.7 10.2 5.0 3.6 16.6 9.1 6.2 JG.e 3.8

'.1 1.0 10.4 1.6

..?

IJ.6 13.1 4.)

1.5 2.7 13.8 i,

Total outage during coastercial i

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.706 4605 2102 768 IM6 1818 278% 19 % A52

'*)

It 1 2008 64174 I

w operation 1

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'. 3 N.1 15.1 19.

'2.9 31.8

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During 1976 (and consider-ing all of the reported outage data) the average number of forced outages for each nuclear plant was 12, with each outage averaging 92 hours0.00106 days 0.0256 hours 1.521164e-4 weeks 3.5006e-5 months in duration.

i The average number of scheduled outages was four per plant, with each averag-ing 399 hours0.00462 days 0.111 hours 6.597222e-4 weeks 1.518195e-4 months in duration.

3.4 Proximate Cause of Plant Outages Outage events and proximate causes are summarized in Table 3-3.

Outage cause was selected by the f4RC staf f to be in one of eight categories as follows:

(1) refueling (scheduled), (2) equipment failure (forced), (3) maintenance or test (primarily scheduled), (4) operational error (forced), (5) regulatory restriction (forced and scheduled), (6) administrative (forced and scheduled),

(7) training and licensing (scheduled), and (8) other.

The operational error category includes any plant personnel errors which caused a forced outage.

Scheduled refuelings required the most outage time of all causes with 49,484 hours0.0056 days 0.134 hours 8.002645e-4 weeks 1.84162e-4 months (33%).

This was followed closely by equipment failures (forced) with 43,886 hours0.0103 days 0.246 hours 0.00146 weeks 3.37123e-4 months or 30% of all outage time.

Scheduled maintenance or testing consumed 27,009 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months - 18%.

Forced maintenance or testing accounted for 9876 hours0.114 days 2.743 hours 0.0163 weeks 0.00376 months (7%).

Browns Ferry 1 accounted for 5231 hours0.0605 days 1.453 hours 0.00865 weeks 0.00199 months and Browns Ferry 2 accounted for 4631 hours0.0536 days 1.286 hours 0.00766 weeks 0.00176 months .

Both plants were conducting a preoperational retest program following modification and repairs necessitated by extensive damage caused by a cable tray fire on March 22, 1975.

Regulatory restrictions

accounted for 9463 hours0.11 days 2.629 hours 0.0156 weeks 0.0036 months (6%) of scheduled outage time.

Lacrosse accounted for 4154 hours0.0481 days 1.154 hours 0.00687 weeks 0.00158 months by adding a diesel generator to comply with I4RC ECCS Interim Acceptance Criteria.

At Big Rock-Point, about 3215 hours0.0372 days 0.893 hours 0.00532 weeks 0.00122 months 'were required to install a reactor depressurization system and modify the ECCS.

The'only other major outage for this cause was at Humboldt Bay where approximately 1344 hours0.0156 days 0.373 hours 0.00222 weeks 5.11392e-4 months were required for seismic modifications.

Each of the other causes of outages resulted in 2% or less of the total outage time.

3.5 Systems and Components Associated With Plant Outages Graphic representation of plant outages is shown in Tables 3-4 and 3-5.

These tables classity outages by type, and identify system, component, plant, and cause.

Outage duration in hours and the percent of the total outage time is listed for major groupings.

The size of each box is proportional to the hours involved to the nearest 1%.

The system and component classifications used in this report are listed in Appendix B.

Because of the fundamental differences between BWRs and PWRs, they are discussed separately.

r

See Glossary - Appendix A.

3-4 I

b

~

Table 3-2 Summary of Nuclear Plant Outages by Type for 1976 Forced Outages Scheduled Outages Total Outages Plant Type (number)

Number of Outage Duration Number of Outage Duration Nu=ber of Outaga Duration Events (hours)

Events (hours)

BW 1 ants 248 25,827 86 38,347 334 64,174 AV 11 1,123 4

1,667 15 2,790 BR at 414 34,634 133 49,334 547 83,968 3)

Average Per 13 1,082 4

1,542 17 2,624 PklR Plant A1 (5 )

Average Per 12 1,099 4

1,594 16 2,693 Plant Average Outage Duration Per 92 399 168 Plant

Table 3-3 Proximate Cause of Outages During 1976 Forced Outages Scheduled Outage.

- "E" Equipment Maintenance Regulatory Operational Maintenar.ce Regulatory Training &

E

^ "*

Failure or Test Restrictions Error or Test Restrictions Licensing No. of i

195 3

2 38 6

58 la 5

6 1

32S events f

BW Hours of 100l 12175 9869 2369 923 491 10099 18263 9280 606 64174 outage No. of 3 5*.

1 1

51 10 99 24 1

7 1

1 550 events PLTR Hours of 31711 7

120 2599 197 16911 31221 183 169 26 824 83963 outage w

549 4

3 89 16 157 36 6

7 7

2 878 en All j

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% of 63

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18 4

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<1

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All Plants

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3.5.1 Boiling Water Reactors 3.5.1.1 Forced Outages i

Forced outages accounted for 40% of the total BWR outage time, i.e., 35,827 of 64,174 hours0.00201 days 0.0483 hours 2.876984e-4 weeks 6.6207e-5 months .

As indicated in Table 3-4, the electric power system was the dominant system associated with forced outages.

There was a fire at the Browns Ferry plant on March 22, 1975, which destroyed electrical cables and resulted in both Units 1 and 2 being shut down.

The shutdowns continued into 1976 and, following modifications and repairs, considerable effort was devoted to preoperational retesting.

The continuation of the outages at Browns Ferry 1 and 2 accounted for 12,231 of the 12,983 hours0.0114 days 0.273 hours 0.00163 weeks 3.740315e-4 months assigned to the electric power system for 1976.

The reactor coolant system accounted for 7635 hours0.0884 days 2.121 hours 0.0126 weeks 0.00291 months .

The major components involved were valves - 2162 hours0.025 days 0.601 hours 0.00357 weeks 8.22641e-4 months , pipes and fittings - 1683 hours0.0195 days 0.468 hours 0.00278 weeks 6.403815e-4 months , and pumps - 1339 hours0.0155 days 0.372 hours 0.00221 weeks 5.094895e-4 months .

The steam and power system accounted for 2438 hours0.0282 days 0.677 hours 0.00403 weeks 9.27659e-4 months of which 595 hours0.00689 days 0.165 hours 9.837963e-4 weeks 2.263975e-4 months were required for turbines, 397 hours0.00459 days 0.11 hours 6.564153e-4 weeks 1.510585e-4 months for piping, and 355 hours0.00411 days 0.0986 hours 5.869709e-4 weeks 1.350775e-4 months for valves.

Each of the remaining systems accounted for less than 2% of the total outage time.

3.5.1.2 Scheduled Outages Scheduled outages in BWRs total 38,347 hours0.00402 days 0.0964 hours 5.737434e-4 weeks 1.320335e-4 months or 60% of the total BWR outage time.

Refuelings accounted for 18,263 hours0.00304 days 0.0731 hours 4.348545e-4 weeks 1.000715e-4 months or 28%.

Other activities, such as maintenance, oftei. were carried out concurrently with refueling.

However, in general, it was not feasible to prorate the outage time to other than the reactor system and fuel elements.

There were 3916 hours0.0453 days 1.088 hours 0.00647 weeks 0.00149 months accumulated by Fitzpatrick, Brunswick 2, and Peach Bottom 3 to modify the core support plate to eliminate vibration of the LPRM instrument tubes.

The engineered safety system accounted for 5227 hours0.0605 days 1.452 hours 0.00864 weeks 0.00199 months .

The dominant com-ponent was pipes and fittings which required 3226 hours0.0373 days 0.896 hours 0.00533 weeks 0.00123 months .

Big Rock Point installed a reactor depressurization safety system wich accounted for 3215 hours0.0372 days 0.893 hours 0.00532 weeks 0.00122 months .

The entire 4154 hours0.0481 days 1.154 hours 0.00687 weeks 0.00158 months for the electric power system was accumulated at Lacrosse where a second diesel generator and associated switchgear were installed to bring the facility into compliance with the NRC's interim acceptance criteria for ECCS.

The reactor coolant system required 3614 hours0.0418 days 1.004 hours 0.00598 weeks 0.00138 months , of which 2027 hours0.0235 days 0.563 hours 0.00335 weeks 7.712735e-4 months were for pipes and fittings, and 926 hours0.0107 days 0.257 hours 0.00153 weeks 3.52343e-4 months were for valves.

The steam and power

~

system required 1698 hours0.0197 days 0.472 hours 0.00281 weeks 6.46089e-4 months .

The remaining 604 hours0.00699 days 0.168 hours 9.986772e-4 weeks 2.29822e-4 months consisted of 402 hours0.00465 days 0.112 hours 6.646825e-4 weeks 1.52961e-4 months for the radioactive waste system, 102 hours0.00118 days 0.0283 hours 1.686508e-4 weeks 3.8811e-5 months for instrumentation and controls, and 100 hours0.00116 days 0.0278 hours 1.653439e-4 weeks 3.805e-5 months was listed as "not applicable." Unit 2 of the Brunswick plant remained shut down for an estimated 100 hours0.00116 days 0.0278 hours 1.653439e-4 weeks 3.805e-5 months so that ECCS testing could be performed on Unit 1.

3-9

3.5.2 Pressurized Water Reactors 3.5.2.1 Forced Outages Forced outages accounted for 41% of the total PWR outage time, i.e., 34,634 of 49,334 hours0.00387 days 0.0928 hours 5.522487e-4 weeks 1.27087e-4 months .

The largest portion of the forced outage time was the result of problems with the steam and power system.

Surry 2 accumulated 2915 hours0.0337 days 0.81 hours 0.00482 weeks 0.00111 months as the result of steam generator tube leakage.

Problems with heat exchangers at other plants brought the total for this category to 6787 hours0.0786 days 1.885 hours 0.0112 weeks 0.00258 months .

Generator problems accounted for 5777 hours0.0669 days 1.605 hours 0.00955 weeks 0.0022 months ; of this total 4539 hours0.0525 days 1.261 hours 0.0075 weeks 0.00173 months were accumulated at Rancho Seco to perform a complete generator stator coil rewind.

Turbine problems were also a significant factor in the steam and power system forced outages, accounting for 4118 hours0.0477 days 1.144 hours 0.00681 weeks 0.00157 months .

The reactor coolant system accounted for 5290 hours0.0612 days 1.469 hours 0.00875 weeks 0.00201 months of forced outage time with 2,735 hours0.00851 days 0.204 hours 0.00122 weeks 2.796675e-4 months due to pump failures.

The 3270 hours0.0378 days 0.908 hours 0.00541 weeks 0.00124 months assigned to the reactor system consists of 1597 hours0.0185 days 0.444 hours 0.00264 weeks 6.076585e-4 months to repair or remove the reactor vessel specimen holder tubes; 1420 hours0.0164 days 0.394 hours 0.00235 weeks 5.4031e-4 months for control rod drive problems; and 253 hours0.00293 days 0.0703 hours 4.183201e-4 weeks 9.62665e-5 months for a variety of other components.

The electric power system accounted for 1783 hours0.0206 days 0.495 hours 0.00295 weeks 6.784315e-4 months .

All other systems accounted for 1% or less of tL total outage time.

l 3.5.2.2 Scheduled Outages Scheduled ov.' aces in PWRs totalled 49,334 hours0.00387 days 0.0928 hours 5.522487e-4 weeks 1.27087e-4 months or 59% of the total PWR outage time.

The reactor system accounted for 36,516 hours0.00597 days 0.143 hours 8.531746e-4 weeks 1.96338e-4 months , of which 31,221 hours0.00256 days 0.0614 hours 3.654101e-4 weeks 8.40905e-5 months was for refueling and 3973 hours0.046 days 1.104 hours 0.00657 weeks 0.00151 months was to repair or remove reactor vessel specimen holder tites.

The only other system accounting for more than 1% of the total outage time was the steam and power system with 11% or 9228 hours0.107 days 2.563 hours 0.0153 weeks 0.00351 months .

The dominant component in this system was heat exchangers with 8% of the total time, or 6966 hours0.0806 days 1.935 hours 0.0115 weeks 0.00265 months .

l 3.5.3 Observations on BWR and PWR Outages 3.5.3.1 Forced Outages Twenty-three BWR plants experienced 25,827 hours0.00957 days 0.23 hours 0.00137 weeks 3.146735e-4 months of forced outage; an overall average of 1123 hours0.013 days 0.312 hours 0.00186 weeks 4.273015e-4 months per plant.

Thirty-two PWR plants experienced 34,634 hours0.00734 days 0.176 hours 0.00105 weeks 2.41237e-4 months of forced outage san overall average of 1082 hours0.0125 days 0.301 hours 0.00179 weeks 4.11701e-4 months per plant.

l l

Additional insight as to the relative outages in BWRs and PWRs may be obtained by reviewing the data in Table 3-6 which compares the outage percentage and the average number of hours per plant for the listed component, which contributed 1%

l or more of the total outage time.

l The dominant component contributing to PWR forced outage time was heat exchangers accounting for 6787 hours0.0786 days 1.885 hours 0.0112 weeks 0.00258 months or 212 hours0.00245 days 0.0589 hours 3.505291e-4 weeks 8.0666e-5 months per plant.

This was followed closely by generators with 5777 hours0.0669 days 1.605 hours 0.00955 weeks 0.0022 months or 181 hours0.00209 days 0.0503 hours 2.992725e-4 weeks 6.88705e-5 months per plant.

At BWRs, a disproportionate amount of time was attributed to electrical conductors because of a fire which occurred at Browns Ferry on March 22, 1975, shutting down two reactor units for the remainder of 1975 and a combined total of 12,231 hours0.00267 days 0.0642 hours 3.819444e-4 weeks 8.78955e-5 months in 1976.

The second most dominant component at BWRs was valves, averaging only 94 hours0.00109 days 0.0261 hours 1.554233e-4 weeks 3.5767e-5 months per unit.

3-10 c

L Table 3-6 Components Involved in Forced ~utages PWR BWR Outage Type System Component

% Avg. hrs.

, Avg. hrs.

4 Forced Steam & Power Heat Exchangers 8

212 Generators 7

181 Turbines 5

129 1

26 Piping 2

41 19 Pumps 1

33 Valves 1

31 Shock Suppressors 1

20 Reactor Coolant Pumps 3

85 2

58 Vessels 1

30 2

52 Motors 1

15 Valves 3

94 Piping 3

73 Valve Operators 1

22 Reactor Inte rnals 2

57 Control Rod Drives 2

41 Fuel 1

37 Electric Power Generators 1

34 Electrical Conductors 19 540 s

e 3-11

3.5.3.2 SCHEDULED OUTAGES The 23 BWRs had 38,347 hours0.00402 days 0.0964 hours 5.737434e-4 weeks 1.320335e-4 months of scheduled outage time for an average of 1667 hours0.0193 days 0.463 hours 0.00276 weeks 6.342935e-4 months per plant. The 32 PWRs accumulated 49,334 hours0.00387 days 0.0928 hours 5.522487e-4 weeks 1.27087e-4 months for an average of 1542 hours0.0178 days 0.428 hours 0.00255 weeks 5.86731e-4 months per plant.

The scheduled outages in the two types of reactors are compared in Table 3-7 on the basis of percent outage and average number of hours per plant.

The comparison is made where a listed component for either reactor type contributed 1% or more of the total outage time.

Obviously fuel elements, the component involved in refuelings, was the dominant component at both types of reactors.

The percentage of outage time for PWRs was greater than for BWRs, averaging about 186 hours0.00215 days 0.0517 hours 3.075397e-4 weeks 7.0773e-5 months longer.

Other than fuel elements, the dominant component at PWRs was heat i

exchangers requiring 8% of the total outage time.

At BWRs the dominant components, other than fuel elements, were reactor vessel internals and generators, each accounting for about 6% of the scheduled outage time per unit.

3.5.4

SUMMARY

l During 1976, the 23 operating BWRs experienced an average of 2790 hours0.0323 days 0.775 hours 0.00461 weeks 0.00106 months of outage time compared to an average of 2624 hours0.0304 days 0.729 hours 0.00434 weeks 9.98432e-4 months for the 32 operating PWRs. The percent forced outage at BWRs was 40% compared to 41% at PWRs.

The primary cause of forced outages at both BWRs and PWRs was equipment failures.

Refueling was the primary cause of scheduled outages at both BWRs and PWRs. Maintenance or testing also accounted for a large percentage of the scheduled outage time at both types of plants.

i 3-12 kJ

Table 3-7 Components Involved in Scheduled Outages l

1 PWR BWR Outage Type System Component

% Avg. brs.

., Avg. hrs.

A Scheduled Reactor Fuel Elements 37 980 28 794 Internals 5

129 6

170 Instrumentation 1

25 Piping 1

23 Steam & Power Heat Exchangers 8

218 Valves 1

20 Generators 1

41 Ent;ineered Safety Piping 5

140 Pressure vessels 2

55 l

Electric Power Generators 6

181 Reactor Coolant Piping 3

88 Valves 1

40 s

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NUCLEAR POWER PLANT OPERATING EXPERIENCE 1974 - 1975 Manuscript Completed: March 1977 Date Published: April 1977 i

i!

Office of Management Information and Program Control U. S. Nuclear Regulatory Commission Washington, D. C. 20555

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3.0 PLANT OUTAGES 3.1 Plant Outages - 1974 Review of the plant outages or shutdowns that occurred during 1974 provides a means of assessing the nature, number and extent of the operating problems experienced at nuclear power plants, as well as the principal systems and components involved. Most of the data were obtained either from the licensees periodic operating reports or from the data reported by the licensee for the NRC's monthly " Operating Units Status Report."

In some instances omissions or inconsistencies in the reported data necessitated checking with the licensee.

In a fcw cases, outage type was classified dif-forently than reported by the licensee. Where appropriate and sufficient information was available, major outages were subdivided to reflect more accurately the true nature of the work performed during the outage..The forced extension of a scheduled outage was generally reclass,1fied by the NRC staf f as a forced outage.

In a few cases, work that had been scheduled for later in the year was rescheduled so it could be performed during an unexpected forced outage. These cases were classified as scheduled outages. Refueling of the reactor is classified as a scheduled outage.

In reviewing the outage data, it should be noted that there are significant dif ferences in nuclear plant designs, even between plants of a given type.

Therefore, care should be used in interpreting the data.

3.1.1 Plant Outages Statistics There were 699 outages requiring 113,782 hours0.00905 days 0.217 hours 0.00129 weeks 2.97551e-4 months of plant downtime reported by the 40 nuclear power plants which were in commercial operation during 1974 os listed in Tables 3-la and 3-lb.

It should be noted that eight of the listed plants were not in commercial operation until long after the first of the year.

The calculated percent outages and unit availability factors listed in Tables 3-la and 3-lb consider only the period of time af ter the plants were in commercial ope ra t ion.

However, in subsequent outage analyses herein, all outages (includ-ing those reported as occurring before commercial operation began) were reviewed to ascertain the type of outage (forced or scheduled), cause, method of shutdown, duration, and the plant system an<1 component primarily associated with the outage.

For the 40 plants thus reviewed, the average total outage time during commercial operation was 32.7% of the year, the average forced outage time was 14.0% and the average scheduled outage time was 18.6%.

The average total unit availability for the 40 plants considering only the period when they were in commercial operation was 67.3%.

The average performance of the BWRs was somewhat better than the average performance of the PWRs by all of the above measures. However, the PWR statistics were distorted by Palisades which was down* 94.5% of the year due to major repairs to it s steam generator, condenser tubes and turbine. >

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1

1, 3.1.2 Types of Outages Identification of types and causes of major outages for each pla~nt in commercial operation is contained in Tables 3-la, 3-lb.

To provide an overview of plant outages, these tables list plant availability, percent of scheduled, forced and total outages with duration, and the major systems and components causing outages lasting longer than five days.

As shown in these tables, twenty-one of the plants experienced shutdowns for replacement of fuel, and fourteen plants had major outages caused by the main turbine generator. Pumps and valves continue to be a major source of trouble accounting for 14 and 11, respec tively, o f the major outages. Also of importance were 12 steam generator outages (from the 23 PWR plants). Other causes of more than five major outages include hydraulic restraints - 9 and the condenser and feedwater system - 8.

Table 3-2 summarizes the outages by type (i.e., scheduled or forced) and indicates the relative impact on plant operations. During 1974 (and considering all of the reported outage data) the average number of forced outages for each nuclear plant was 13, with each outage averaging 108 hours0.00125 days 0.03 hours 1.785714e-4 weeks 4.1094e-5 months in duration. The average number of scheduled outages was 5 per plant, with each averaging 319 hours0.00369 days 0.0886 hours 5.274471e-4 weeks 1.213795e-4 months in duration.

Excluding time for additional work, which was conducted during the same shutdown, the average duration of refueling outages was 1694 hours0.0196 days 0.471 hours 0.0028 weeks 6.44567e-4 months . Iloweve r, it is not always possible to determine if the refueling outage was extended for other work.

The times charged as refueling ranged from 1205 hours0.0139 days 0.335 hours 0.00199 weeks 4.585025e-4 months to 3000 hours0.0347 days 0.833 hours 0.00496 weeks 0.00114 months .

3.1.3 Proximate Cause of Plant Outages Outage events and proximate causer, are summarized in Table 3-3.

Outage cause was selected by the NRC staff to be in one of seven categories listed in order of importance (1) equipment failures (forced), (2) refueling (sc' e iuled), (3) maintenance or test (both forced and scheduled), (4) regulatory restrictions (both forced and scheduled), (5) operator error (forced), (6) training and licensing (scheduled), and (7) other.

The operator error category includes errors by plant personnel which caused a forced outage.

Equipment failure was the single largest cause of nuclear plant outages, account-ing for 40% of the total outage time.

Refueling outages took 30% of the total outage time; operational errors accoueted for 89 outages, but only amounted to 2% of the total outage time.

Scheduled maintenance accounted for 22% of the total outage time; regulatory restrictions ac..ounted for 6% and training and 1icensing examinations amounted to less than 1% of the outage time.

Nine outages were classified as "other" which consisted of tornado and storm damage to lines and equipment and other miscellaneous internal causes.

3.1.4 System:, g Components Associated sith Plant Outanes craphic representatton of plant outages is shown in Tables '3-4 and 3-5.

These tables classify outages by type, and identify system, component, plant, and.

l l

Table 3-2.

Summary of Nuclear Plant Outages by Type for 1974 Forced Outages Scheduled Outages Total Outages 7

j (number)

Outages Duration Outage Duration Outage Duration Number of Events (hours)

Number of Events (hours)

BWR Plants (17) 191 18,493 72 25,354 263 43,847 Average Per BWR Plant 11 1,088 4

1,491 15 2,579 j

PWR Plants (23) 331 34,884 109 35,051 440 69,935*

i i

y Average Per l

PWR Plant 14 1,517 5

1,524 19 3,041 l

All Plants (40) 522 53,377 181 60,405 703 113,782*

l Overall Average Per i

i Plant 13 1,334 5

1,510 18 2,845 l

Av' rage Catage Durction Per Event 102 334 162 l

l

There are 1981 additional shutdown hours in 4 shutdowns for Oconee No. 2 that are not included in this i

)

Table. Detailed data are not available.

1 i

i I

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Table 3-3.

Proximate Cause of Outages During 1974 FORCED OUTAGE SCHEDULED OUTAGE EVENTS TOTALS Equipment Maintenance Regulatory Operator

"#"C

E"

Y

"'"'"E Other Refueling Other Failure or Test Restrictions Error or Test Restrictions Licensing No. of Events 141 il 2

28 4

48 12 3

7 1

263 BWR Hours of 12,783 1514 2092 1955 149 5696 20,527 43b 238 9

43,847 Outage i

No. of N

Events 236 27 1

61 6

88 1/2 9 1/2 2

9 0

440 PWR Hours of 32,915 1057 21 834 57 19,110 14,165 1465 311 0

69,935 Outage No. of Events 377 44 3

89 10 136 1/2 21 1/2 5

16 1

703 A % of L Total 54 06 01 13 01 19 03 01 02

>0 100 L

Totel P Outage 45,698 2571 2113 2789 206 24,806 34,692 1903 549 9

113,789 L Hours A

N % of 40 02 02 02

<01 22 26 02

<01

>0 100 T Total S

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% ARIOUS 2 e._m0h lll 16w 11 1660i:

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f O

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n

cause. Outage duration in hours and the percent of the total outage time is listed for major groupings. The size of each box in Tables 3-4 and 3-5 is proportional to the hours involved to the nearest 11.

The system and component classifications used in this report are defined in Appendix A; because of the fundamental differences between BWRs and PWRs, they are discussed separately.

3.1.5 Boiling Water Reactors Forced Outages l

BWR forced outages accounted for 42% of the total outage time, i.e.,

18,492 I

of 43,847 hours0.0098 days 0.235 hours 0.0014 weeks 3.222835e-4 months . As indicated in Table 3-4, the reactor system was the dominant system associated with forced outages; however, most of the 16% of the total outage attributable to this cause was due to a unique problem at one plant, Pilgrim (fuel channel to poison curtain interaction). The reactor coolant system with 14% was also a major system involved in forced outages, but no one plant accounted for more than 995 hrs, i.e.,

s2%.

The steem and power system with 4% outage time accounted for 1902 hours0.022 days 0.528 hours 0.00314 weeks 7.23711e-4 months of tbo total A3,847 hours0.0098 days 0.235 hours 0.0014 weeks 3.222835e-4 months with no single event dominating. The auxiliary process and cuxiliary water systems each accounted for %2% of the total outage time.

The block designated as "others" accounted for 722 hours0.00836 days 0.201 hours 0.00119 weeks 2.74721e-4 months .

This was comprised of: electric power - 214 hours0.00248 days 0.0594 hours 3.53836e-4 weeks 8.1427e-5 months ; radwaste systems - 195 hours0.00226 days 0.0542 hours 3.224206e-4 weeks 7.41975e-5 months ; instrumentation and controls - 177 hours0.00205 days 0.0492 hours 2.926587e-4 weeks 6.73485e-5 months ; and other auxiliary systems - 136 hours0.00157 days 0.0378 hours 2.248677e-4 weeks 5.1748e-5 months .

Scheduled Outages Scheduled outages in BWRs totaled 25,355 hrs or 58% of the total outage time.

Refuelings accounted for most, i.e.,

47%. Other activities, including major maintenance, of ten were carried out concurrently with refueling. Ilowever, in general, it was not feasible to prorate the outage time to other than the reactor system and fuel elements.

The reactor coolant system was involved in 5% (2355 hours0.0273 days 0.654 hours 0.00389 weeks 8.960775e-4 months ) of the total BWR plant outage time.

Activities associated with this system included both maintenance and testing.

The steam and power, radioactive waste, and engineered safety features each accounted for 1% of the outage time.

The time indicated as others represents 97 hours0.00112 days 0.0269 hours 1.603836e-4 weeks 3.69085e-5 months ; of this subtotal, the following distribution occurred: clectric power - 46 hours5.324074e-4 days 0.0128 hours 7.60582e-5 weeks 1.7503e-5 months ; auxiliary water - 33 hours3.819444e-4 days 0.00917 hours 5.456349e-5 weeks 1.25565e-5 months ; and instrumentation and controls - 18 hours2.083333e-4 days 0.005 hours 2.97619e-5 weeks 6.849e-6 months .

. t 4

A

]I it 1

i 5

i 3.1.6 Pressurized Water Reactorn Forced Outages Forced outages in PWRs accounted for 49% of the total outage time, f.e.,

34,884 of 71,916 hrs.

This total outage time includcs 1981 hrs or 2% of the total outage time at Oconee 1, which was undesignated and is listed separately herein. The largest portion of the forced outage time was the result of problems with the steam and power system.

This includes the turbines which accounted for 9828 hours0.114 days 2.73 hours 0.0162 weeks 0.00374 months (14%), heat exchangers which accounted for 8459 hours0.0979 days 2.35 hours 0.014 weeks 0.00322 months (12%), electrical generators (5%), pipes and fittings (4%), and various others another 2%.

The turbine outages were largely attributable to problems at three plants (Surry 2, Cinna, and Prairie Island 1).

The heat exchanger out-age was principally due to Palisades (10%), while 7. ion 2 was principally responsible for the electrical generator outage time.

Problems wi'.h the reactor coolant system accounted for 6083 hours0.0704 days 1.69 hours 0.0101 weeks 0.00231 months of outage time, of which pumps and valves were the dominant components involved. The reactor system accounted for 1078 hours0.0125 days 0.299 hours 0.00178 weeks 4.10179e-4 months , of which control rod drive mechanisms required 906 hours0.0105 days 0.252 hours 0.0015 weeks 3.44733e-4 months for repair.

The 1443 hours0.0167 days 0.401 hours 0.00239 weeks 5.490615e-4 months listed as "others" include the following: undetermined - 507 hours0.00587 days 0.141 hours 8.382936e-4 weeks 1.929135e-4 months ; electric power - 457 hours0.00529 days 0.127 hours 7.556217e-4 weeks 1.738885e-4 months ; instrumentation and controls - 228 hours0.00264 days 0.0633 hours 3.769841e-4 weeks 8.6754e-5 months ; auxiliary process - 191 hours0.00221 days 0.0531 hours 3.158069e-4 weeks 7.26755e-5 months ; engineered safety features - 39 hours4.513889e-4 days 0.0108 hours 6.448413e-5 weeks 1.48395e-5 months ; and radia-tion protection - 21 hours2.430556e-4 days 0.00583 hours 3.472222e-5 weeks 7.9905e-6 months .

Scheduled Outages Scheduled outages in PWRs totaled 35,051 hrs or 49%.

The reactor system accounted for 14,551 hours0.00638 days 0.153 hours 9.11045e-4 weeks 2.096555e-4 months of outage time, of which 14,165 hours0.00191 days 0.0458 hours 2.728175e-4 weeks 6.27825e-5 months was for refueling. Problems with the steam and power system accounted for 10,708 hours0.00819 days 0.197 hours 0.00117 weeks 2.69394e-4 months due primarily to problems with heat exchangers, generators, and turbines.

The reactor coolant systems required 7927 hours0.0917 days 2.202 hours 0.0131 weeks 0.00302 months , of which 4344 hours0.0503 days 1.207 hours 0.00718 weeks 0.00165 months were due to problems with pump and 2168 hours0.0251 days 0.602 hours 0.00358 weeks 8.24924e-4 months were for inspection and repair of shock suppressors. The engineered safety features required 1514 hours0.0175 days 0.421 hours 0.0025 weeks 5.76077e-4 months for maintenance; 123 hours0.00142 days 0.0342 hours 2.03373e-4 weeks 4.68015e-5 months were undeterminable, and 228 hours0.00264 days 0.0633 hours 3.769841e-4 weeks 8.6754e-5 months were accounted for by other systems.

Undetermined There were 1981 hours0.0229 days 0.55 hours 0.00328 weeks 7.537705e-4 months of outage time at Ocence 2 for which no information was available.

3.1.7 Observation on BWR and PWR Outanes Forced Out m l

Seventeen BWR plants experienced 18.492 hours0.00569 days 0.137 hours 8.134921e-4 weeks 1.87206e-4 months of forced outage; an overall average of 1088 hours0.0126 days 0.302 hours 0.0018 weeks 4.13984e-4 months per plant.

Twenty-three PWR plant s experienced 34,884 hours0.0102 days 0.246 hours 0.00146 weeks 3.36362e-4 months of forced outage; an overall average of 1517 hours0.0176 days 0.421 hours 0.00251 weeks 5.772185e-4 months per plant.

(The PWR plants also had 1981 hours0.0229 days 0.55 hours 0.00328 weeks 7.537705e-4 months of outage for which a determination of forced or scheduled could not be made.)

Additional insight as to the relative outages in BWRs and PWRs may be obtained by using the data in Tables 3-4 and 3-5, and comparing the outage percentage and the average number of hours attributable to various causes. This is done below where a listed component for either reactor type contributed more than 1% of the total outage time.

PWR BWR Outage Type System Component

% Avg. hrs.

Forced Reactor Fuel Elements 0

11 293 Control Rod and Drive

<1 5

122 Reactor Pumps 5

148 1

33 Valves 2

48 5

144 Pipes and Fittings 2

33 4

92 Shock Suppressors

<1 2

51 Steam &

Turbines 14 427 1

21 Heat Exchangers 12 368 1

31 Generators 5

151 Pipes and Fittings 4

125 Auxiliary Pumps

<1 2

41 ys ems Filters

<1 2

44 The dominant component contributing to BWR forced outage time was fuel elements

- 4987 hours0.0577 days 1.385 hours 0.00825 weeks 0.0019 months - because of the problem at Pilgrim with fuel channel to poison curtain interaction. At PWRs, the dominant component was the steam turbines accounting for 9828 hours0.114 days 2.73 hours 0.0162 weeks 0.00374 months or 427 hours0.00494 days 0.119 hours 7.060185e-4 weeks 1.624735e-4 months per plant. This was followed closely by heat exchangers which averaged 368 hours0.00426 days 0.102 hours 6.084656e-4 weeks 1.40024e-4 months per plant. Forced outage for both of these components was significantly lower at BWRs, but they do not employ steam generators which was the principal component in the heat exchanger classification. Both reactor types had comparable forced outage for total of pumps and valves, but BWRs had more outage for control rods (and drives),

and auxiliary systems.

, 4 J

]"

Scheduled Outages The seventeen BWRs had 25,355 hours0.00411 days 0.0986 hours 5.869709e-4 weeks 1.350775e-4 months of scheduled outage time for an average of 1491 hours0.0173 days 0.414 hours 0.00247 weeks 5.673255e-4 months per plant. The twenty-three PWRs accumulated 35,051 hours5.902778e-4 days 0.0142 hours 8.43254e-5 weeks 1.94055e-5 months for an average of 1524 hours0.0176 days 0.423 hours 0.00252 weeks 5.79882e-4 months per plant. The scheduled outages in the two types of reactors are compared below on the basis of percent outage and the average number of hours attributable to various causes (>1%).

PWR BWR Outage Type System Component

% Avg. hrs.

% Avg. brs.

Scheduled Reactor Fuel Elements 20 616 47 1207 Reactor Pumps 6

189 1

25 Valves 1

33 1

22 Shock Suppressors 3

94

<1 Steam &

Heat Exchangers 6

171

<1 Generators 4

142 0

Turbines 3

86

<1 Refueling at BWRs accounted for 20,527 hours0.0061 days 0.146 hours 8.713624e-4 weeks 2.005235e-4 months (average 1207) and at PWRs 14,165 hours0.00191 days 0.0458 hours 2.728175e-4 weeks 6.27825e-5 months (average 616), reflecting the greater refueling undertaken at BWRs during the past year.

However, each PWR plant also experienced an average of 831 hours0.00962 days 0.231 hours 0.00137 weeks 3.161955e-4 months for maintenance or test vs the BWR average of 243 hours0.00281 days 0.0675 hours 4.017857e-4 weeks 9.24615e-5 months . The scheduled outages for maintenance and testing in PWRs involved primarily pumps, shock suppressors, heat exchangers, generators and turbines.

3.1.8 Summary During 1974 the 17 operating BWRs experienced an average of 2579 hours0.0298 days 0.716 hours 0.00426 weeks 9.813095e-4 months of outage compared to an average of 3127 hours0.0362 days 0.869 hours 0.00517 weeks 0.00119 months for the 23 operating PWRs.

This average total outage divided between forced and scheduled outages for both reactor types; 1088 and 1492 hours0.0173 days 0.414 hours 0.00247 weeks 5.67706e-4 months respectively for BWRs and 1517 and 1524 hours0.0176 days 0.423 hours 0.00252 weeks 5.79882e-4 months respectively (plus another 86 hours9.953704e-4 days 0.0239 hours 1.421958e-4 weeks 3.2723e-5 months for the undesignated outage at Oconee 1) for PWRs.

The outage experience in the two reactor types is not sufficiently extensive i

and/or similar to permit meaningful, comparative analysis. The difference in the forced outage time could be attributed to the steam generators (which BWRs do not have), but there is little parallel in the remaining forced outage data except perhaps for the persistence of problems dealing with such things as pumps, valves, pipes and fittings.

i i

The scheduled outage in BWRs was almost entirely attributable to refueling activities whereas in PWRs it was more equally divided between refueling and scheduled maintenance (or test). While refueling activities in BWRs average 1207 hours0.014 days 0.335 hours 0.002 weeks 4.592635e-4 months vs 616 hours0.00713 days 0.171 hours 0.00102 weeks 2.34388e-4 months in PWRs, these numbers reflect a higher frequency of refueling in BWRs (12 out of 17) than in PWRs (9 out of 23).

However, a comp.lete refueling operation averaged 1632 hours0.0189 days 0.453 hours 0.0027 weeks 6.20976e-4 months for 10 BWRs, and 1771 hours0.0205 days 0.492 hours 0.00293 weeks 6.738655e-4 months for 8 PWRs.

(For both reactor types refueling outages occurred that were not considered in the averages, because they extended over other years.)

Moreover the extreme (high and low) times required for refueling differed by a factor >2, which suggests both that some scheduled maintenance may be responsible for the longer times, and that the average time for refueling may be significantly reduced.

3.2 Plant Outanes - 1975 Review of the plant outages or shutdowns that occurred during 1975 provides a means of assessing the nature, number and extent of the operating problems experienced at nuclear power plants, as well as the principal systems and components involved. Most of the data were obtained either from the data reported by the licensee for the NRC's monthly " Operating Units Status Report," although in some instances it was necessary to check information in the licensees periodic operating reports.

In some instances omissions or inconsistencies in the reported data neces-sitated checking with the licensee.

In a few cases, outage type was classified differently than reported by the licensee. Where appropriate and sufficient information was available, major outages were subdivided to reflect more accurately the true nature of the work performed du' ring the outage.

The forced extension of a scheduled outage was generally reclassified by the NRC staff as a forced outage.

In a few cases, work that had been scheduled for later in the year was rescheduled so it could be performed during an unexpected forced outage. These cases were classified as scheduled outages.

Refueling of the reactor is classified as a scheduled outagu.

s -

Data sheets for all the plants considered are contained in Appendix B.

In reviewing the outage data, it should be noted that there are significant differences In nuclear plant designs, even between plants of a given type.

Therefore, care should be used in interpreting the data.

3.2.1 Plant Outage Statistics There were 854 outages requiring 121,903 hours0.0105 days 0.251 hours 0.00149 weeks 3.435915e-4 months of plant downtime reported by the 51 nuclear power plants which were in commercial operation during 1975 as listed in Tables 3-6a and 3-6b.

It should be noted that eight of the listed plants were not in commercial operation until af ter the first of the year. The calculated percent outages and unit availability factors listed consider only the period of time after the plants were in commercial operation.

However, in subsequent outage analyses herein, all outages (including those reported as occurring before commercial operation began) were reviewed to ascertain the type of outage (forced or scheduled), cause, method of shutdown, duration, and the plant system and component primarily associated with the outage. \\

a

I l

l Table 3-6a sumurary of PWR Power Plant Jatases During Creeerc ial Operat ion 116 1975 7

1 k

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17 O*e PI"e Oa" I

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e)

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1. Arkansas 1 1 00 100 1566 17.9 529

6. 0 2095 23.9 76.1*

2 1

l

2. Calvert Ca tf ts 1 100 65.2 185 3.3 801 14.0 966 17.3 52.7*

1 1

3. G.nnec t icut V ar.kee 100 100 1152 13.2 63 0.7 1215 13.9 86.1 1

4. Coom 1 90 34.8 30 11.1 75 2.5 415 13.6 B6. 4' 1

5. Fort Calhoun 100 100 2714 31.0 119 1.6 2553 32.6 67.4 1

1 1

6. Canna 100 100 1727 19.7 324 3.7 2051 23.4 76.6*

1 7 Indian Point 2 100 100 1560 17.8 652 7.4 2212 25.2 74.8 "a

1 1

1

8. Kew. nee 100 100 299 3.)

743 8.5 1032 11.8 85.2 1

1 9.

Maine Y ar.kee 100 tuo 1492 17.1 265 3.0 1757 20.1 79.9 1

1

10. C(unee 1 100 1D0 1914 21.8 171 2.0 2085 23.8 76.2 1

2

11. owne e 2 100 IN

.2 5.1 1914 21.8 2356 26.9 73.1 1

2 2

12. a unee 1 100 IW 1110 12.6 891 10.2 2001 22.8 77.2 1

1 3

1

11. P a ! 1 *ade n 100 1 00 35!

4.0 2757 31.5 1108 35.5 64.5 1

2 1

PJ

14. Point se as h 1 lua 103 1199 13.7 1262 14.4 2e61 28.1 71.9 1

1 2

%D

15. Paint Be a.-h 2 100 160 326

3. 7 209 2.4 535 6.1 93.9 1

I

16. Praarse Inland 1 10J 100 811

9. 2 391 4.5 12C2 13.7 86.3 1

1 1

17. Pr ai r ie 1*Iand 2 100 100 531 6.1 1195 11.6 1726 19.7 40.3 5

g it. Rawiho seso 100 71.7 0

4491 72.5 4.91 72.5 27.5' 1

19. L.b tnesa 2 100 100 1292 14.7 1097 12.6 2389 27.3 72.7 1

1 3

20. San hf re 1 100 100 IC56 12.4 14 0.2 1100 12.6 87.4 1

1 21, we rv 1 100 10v 2602 29.7 732 4.4 3334 38.1 61.9*

2 1

1 1

.. bu ry 2 100 100 1332 15.2 458 5.2 1790 20.4 79.6 1

1 h

2 L Ihree Mile I s l and 1:0 100 617

?. 3 922 IG.5 1559 17.8 82.2 1

1 1

2 3

20.6' 79.4 1

1 1

L---.

.. Turney PcAnt 3 100 IW 1597 1s.2 196 2.3 1809

21. T raev Punt 4 1,00 100 2559 29.2 23

0. 3 2582 29.5 70.5 1

2

26. 1 ranee L>we 100 100 1610 18.4 27

0. 3 1637 18.7 81.3*

1

( _h.. Zion 1

1 &)

100 1313 15.0 1276 14.6 26322 30.02 70.0 1

1 1

1 3

1

(~g,

28. Z ion 2 10G 100 31

0. 3 2335 26.7 2436 27.8 72.2 4

1 2

p 31.768 13.6 23.952 10.2 55.949 23.9 76 1 15 0

6 9

8 11 3

2 2

0 0

11 20 p..

dF la 1 les le he.rs ce t ident ified as either F;,rced or Scheduled.

t uc ludes.3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months not identified as either Forced or ScheJuled.

. ~@

o

-%m

. t a.1 de s 70 hours8.101852e-4 days 0.0194 hours 1.157407e-4 weeks 2.6635e-5 months not 1Jeatified as eit her Forced or Schedated.

Aw aa 14h t 11 t y ceno t e t en t with ost ade data but samewha t lawer than previously published data.

Ca h ulated voirs cmrcial oper at ion only

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e

i 4

Table 3-6b 4

ssw.ar-of B=1t he r Flaat Ata.ca During Cuesmerc ial opee.t ton to 1975

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4"e Els i

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j Jg-2 ge t

Pl 4s t Erc p*'

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p

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g J3 j

n hr s.

I hr s.

I hrs.

I

1. Arnold, i>uane 100 91.8 1060 13.4 640 8.0 1720 21.4 78.6' I

i

2. nig A k I'otr.t 100 100 50 0.6 3472 39.6 3522 40.2 59.5 1

3. Browen Fe r ry 1 100 100 1 60 2.1 7045

80..

7225 82.5 17.5 1

1 1

4. Bres Fer ry 2 Iv0 83.8 0

0 6828 93.0 6828 93.0

7. 0" 1

5 B run.w a. a 2

$ 4.1 16.2 0

0 105 7.4 105 7.4 93.2*

I j

n. C mper 100 100 1010 11.5 426 4.9 1436 16.4 83.6 1

1 1

i

7. Dresden 1 100 100 2tas 7 30.7 1064 12.1 3751 42.8 57.2 1

1 I

8. Lre Jem 2 100 100 3591 41.0 339 3.9 3930 44.9 55.1 1

1

9. Dre sden 3 100 1 >0 35s0 40.3 692 7.9 42523 48.51

$ 1. 5 1

1 1

4

10. Fit spatrl k S0. 4 42.7 43)

II.7 659 17.6 1094 29.3 70.7*

1 3

2

11. ht ch 1 100 0

152,2 gy,$2 10622 12.22 2544?

29.72 70,32 d

12. hushs1Jr B4v 100 100 1269 14.5 145

1. 6 1413 16.1 81.9 1

1

11. La C r osse 100 130 2 3Se 27.2 31 6 3.6 2'02 30.8 69.2*

1 I

L.. Mail twe Pulat 1 100 100 619 7.1 1516 17.3 2135 24.4 75.6 1

1 1

1 l's. %nt ue llo 100 100 2 01 27.4 35 0.4 2436 27.8 72.2 2

16. sine Male r o to t 100 100 2200 25.1 322 3.7 2522 25.8 71.2 1

1 17 Ovster crees 100 100

139, 15.9 944 10.8 2338 26.7 73.3 2

2 1

1 is, reat h But t e 2 130 100 1218 13.9 905 10.3 2123 24.2 75.9 1

o 1

2 1

19. Pe.s h Bot tasa 3 100 100 397 4.5 831 9.5 1228 14.0 86.0 1

3

.9. Filar is 100 100 617 7.0 1900 21.7 2517 28.7 71.3 2

1 2

1 i

g

21. vud cit ies 1 100 100 242 2.7 1067 12.2 1309 14.9 85.1 1

l

. Quad C t t ten 2 100 100 3691 42.1 539 6.2 4230 48.3 51.7 2

1 1

h 2 8. Vereoc t 14ak ee 100 100 715 8.2 358 4.0 1073 12.2 87.8 1

1 l

(

)

29.713 16.7 30.150 16.9 59,8933 33.63 66.4 13 2

0 2

10 7

12 0

0 4

4 11 i

f I

%. t l ab t i t t y cor s istent with os.tage data but somewhat lower than prewfously published data.

C.ilc ulat ed un ang cenrie* tal ope rat ien only.

]

The se numbe rs do net naclude a discrep4ncy of 30 hre additional hours outage which could not be identified.

TW Lt h re.e. t ar was n.-r plai.ed is e nemme rc ia l operation unt ti af te r the f i rst of January 1976. Consequently, this out re dat a is not inc l..Jed in t he tot als of this table.

1 %S E

4 6

1 4

m 1

- m i

T 1

Por the 51 plants thus reviewed, the average total outage time during commercial operation was 28.1% of the year, the average forced outage time was 13.1%,

and the average scheduled outage time was 14.9%.

(The dif ference of 0.1%

between the total and the sum of the scheduled and forced outages is due to I

l 159 hours0.00184 days 0.0442 hours 2.628968e-4 weeks 6.04995e-5 months of unclassified outage at four plants.) The average total unit availability for the 51 plants considering only the period when they were in commercial operation was 71.9%.

The average performance of the PWRs was somewhat bet ter than the average performance of the BWRs by all of the above measures. Ilowever, the 1&'R statistics were dictorted by Browns Ferry 1 and 2, both of which were out of service for the remainder of the year following the fire of March 22, 1975. See Section 4.3 for details of the fire.

3.2.2 Tyyes at Outages _

Identification of types and causes of maior outages f or each plant in com-merc ial operat ion is contained in Tables 3-6a, 3-6h.

To provide an overview of plant outages, these tables list plant availability, percent of scheduled.

forced and total outages with duration, and the major systems and components causing outages last ing longer than f ive days.

As shown in these tables, these plants experienced 28 major outages for refueling with four plants having more than one such outage during the year.

There were 35 ma jor outages attributable to reactor coolant or rec irculating pumps and they af f ected half (i.e.,

25) of the operating plants.

Problems in the condenser and feedwater system accounted for 18 major outages, while valves accounted f or 15.

Also of note were 11 turbine outages (mostly in PWRs), 11 steam generator outages (all in PWRs) and 10 each auxiliary system and engineered saf ety system outages (mostly in BWRs).

Tahle 3-7 summarizes the outages by type (i.e., scheduled or forced) and' indicates the relative impact on plant operations. During 1975 (and considering all of the reported outage data) the average number of forced outages for each nuclear plant was 13, with each outage averaging 90 hours0.00104 days 0.025 hours 1.488095e-4 weeks 3.4245e-5 months in durat Nn.

The average number of scheduled outages was four per plant, wit h each averaging 301 hours0.00348 days 0.0836 hours 4.976852e-4 weeks 1.145305e-4 months in duration.

Excluding time f or add it ional work, which was conducted during the same shutdown, the average duration of ref ueling outages was 1451 hours0.0168 days 0.403 hours 0.0024 weeks 5.521055e-4 months .

(This was obtained by considering only those ref ueling shutdowns which were started and completed within t he calendar year.)

llowever, it is not always possible to determine if the ref ueling outage was extended f or other work.

The t imes charged as refuel ing ranged f rom 938 hours0.0109 days 0.261 hours 0.00155 weeks 3.56909e-4 months to 2508 hours0.029 days 0.697 hours 0.00415 weeks 9.54294e-4 months .

3.2.3 Proximate Cause of Plant Outages Outage events and proximate causes are summarized in Table 3-8.

Outage cause was selected by the NRC staff to be in one of eight categories as f ollows

[1] refueling (scheduled), [2] equipment failure (forced), [1] maintenance or test (primarily scheduled), [4] operational error (f orced ), [5] regulatory restriction (forced and scheduled), [6] administrative (f orced and sc hedul ed),

[7] training and licensing (scheduled), and [8] < ther. The o'perational error category includes any plant personnel errors which caused a forced outage.

Scheduled refuelings required the most outage t ime of all causes with 17,735 hours0.00851 days 0.204 hours 0.00122 weeks 2.796675e-4 months (31%). This was followed closely by equipment failures ( f o rc ed ) with 35,694 hours0.00803 days 0.193 hours 0.00115 weeks 2.64067e-4 months or 29% of all outage time.

Scheduled maint enance or testing consumed 22,951 hours0.011 days 0.264 hours 0.00157 weeks 3.618555e-4 months - 19%.

r-1 I

l l

Table 3-7.

Sunnary of Nuclear Plant Outages by Type for 1975 I

Forced Outages Scheduled Outages Total Outages Plant Type (number)

Number of Outage Duration Number of Outage Duration Number of Outage Duration Events (hours)

Events (hours)

Events (hours) 251 33,487 81 31,490 332 64,977 (23)

^" ##E

[

11 1,456 4

1,369 14 2,825 BWR Plant a

an s k$

390 24,197 132 32,729 522 56,926 (28) i Average Per 14 864 5

1,169 19 2,033 PWR Plant All Plants 641 57,684 213 64,219 854 121,903 (51)

Overall Average Per 13 1,131 4

1,259 17 2,390 Plant l

Average Outage Duration Per 90 301 143 Event f

1 hh

l

. ~... -

1 Table 3-8 Prculcate Cause of Oatages Ouring. 1975 FORCED C' TA0E SCME",11ED Oi;TAGE J

EVENTS Equip ent h intenance Fe g al a t o ry Ad:Inis-Operation 1

nintenance Fe-Pegulatory Training 5 Ad:ints-Otner E

Failure or Test testrictions trative Errcr or Test fueling Festr:ctices Licen>tng trative 192 2

5 2

46 4

57 11 10 1

1 1

332 No. of Events BWR 13,663 31 1303 183 14,670 3,615 9,e53 19.210 1,627 20 31 949 64,977 Hrs of Outage 303 1

0 1

68 12 110 15 0

3 3

1 522 I

No. of Events w

?WR l

22,014 14 0

28 1.457 654 11,298 18,525 0

95 51 760 56,M6 Hrs of Catage i

~

500 3

5 3

114 16 167 26 10 4

4 2

654 No. of Eve n t s 59

<1 1

<1 13 2

20 3

1

<1

<1 100 A T of L Total L

P Tetal Outage 35,694 '

45 IJOB 211 16.157 4,269 22.951 37,735 1,627 115 82 1,709 121. 9 T) g g

Hours 3

29

<1 1

<1

)?

4 19 31 1

<1

<1 1

100 T

of 5,atal e

4

l There was a total of 114 operational errors - 46 at BWRs and 68 at PWRs result-ing in 16,157 hours0.00182 days 0.0436 hours 2.595899e-4 weeks 5.97385e-5 months of forced outage time.

However,13,656 hours0.00759 days 0.182 hours 0.00108 weeks 2.49608e-4 months was due to one incident. The Browns Ferry fire which disabled two units for 6828 hours0.079 days 1.897 hours 0.0113 weeks 0.0026 months each was attributed to an operational error because the fire was started by a candle held by a technician checking containment penetration leakage. The other 112 plant outages attributed to operational errors accounted for only 2501 hours0.0289 days 0.695 hours 0.00414 weeks 9.516305e-4 months which is an average of 22 hours2.546296e-4 days 0.00611 hours 3.637566e-5 weeks 8.371e-6 months per operational error.

There were 4269 hours0.0494 days 1.186 hours 0.00706 weeks 0.00162 months of forced outage classified as other.

The basic causes were varied but included such things as power distribution system disturbance (5 outages), lightning (4), windstorm (1), condenser loaded with fish (1), and seaweed on intake (1).

Each of the other causes of outages (regulatory restriction, administrative training and licensing) resulted in 1% or less l

of the total outage time.

3.2.4 Systems and Components Associated with Plant Outages G raphic representation of plant outages is shown in Tables 3-9 and 3-10.

These tables classify outages by type, and identify system, component, plant, and cause. Outage duration in hours and the percent of the total outage time

[

is listed for major groupings. The size of each box is proportional to the l

hours involved to the nearest 1%.

The system and componeat classifications j

used in this report are listed in Appendix B.

Because of the f undamental differences between BWRs and PWRs, they are discussed separately.

3.2.5 Boiling Hater Reactors Forced Outages 1

BWR forced outages accounted for 52% of the total outage time, i.e.,

33,487 of I

64,977 hours0.0113 days 0.271 hours 0.00162 weeks 3.717485e-4 months . As indicated in Tabic 3-9, the electric power system was the dominant system associated with forced outages. There was a fire at the Browns Ferry plant on March 22, 1975, which destroyed electrical cables and resulted in both Units 1 and 2 being shut down for the remainder of the year.

Each unit accumulated 6828 hours0.079 days 1.897 hours 0.0113 weeks 0.0026 months of outage time.

Thus, 13,656 hours0.00759 days 0.182 hours 0.00108 weeks 2.49608e-4 months of outage time was due to one incident. This represents 21% of the total outage time accumulated by all BWR plants.

The reactor coolant system accounted for 9112 hours0.105 days 2.531 hours 0.0151 weeks 0.00347 months . The major components in-volved were pipes and fittings - 3769 hours0.0436 days 1.047 hours 0.00623 weeks 0.00143 months , pumps - 2991 hours0.0346 days 0.831 hours 0.00495 weeks 0.00114 months , and valves -

1700 hours0.0197 days 0.472 hours 0.00281 weeks 6.4685e-4 months .

I There was 5285 hours0.0612 days 1.468 hours 0.00874 weeks 0.00201 months required for engineered safety feature problems. The dominant component was instruments and controls with 3450 hours0.0399 days 0.958 hours 0.0057 weeks 0.00131 months .

Big Rock Point accounted for 3421 hours0.0396 days 0.95 hours 0.00566 weeks 0.0013 months after it was found that design and QA deficien-cies existed in the instrumentation for the post incident cooling system. k'

I 1lj Table 3-9 i

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The steam and power system accounted for 2769 hours0.032 days 0.769 hours 0.00458 weeks 0.00105 months of which 920 hours0.0106 days 0.256 hours 0.00152 weeks 3.5006e-4 months were required for heat exchangers and 406 hours0.0047 days 0.113 hours 6.712963e-4 weeks 1.54483e-4 months were required for pipes and fittings.

The instrumentatic and controls system outages accounted for 438 hours0.00507 days 0.122 hours 7.242063e-4 weeks 1.66659e-4 months . The 375 hours0.00434 days 0.104 hours 6.200397e-4 weeks 1.426875e-4 months listed as others is comprised of reactor - 195, radioactive waste -

96, auxiliary water - 58, and auxiliary process - 26.

Scheduled Outages Scheduled outages in BWRs total 31.490 hours0.00567 days 0.136 hours 8.101852e-4 weeks 1.86445e-4 months or 48% of the total outage time.

Refuelings accounted for 19,210 hours0.00243 days 0.0583 hours 3.472222e-4 weeks 7.9905e-5 months or 30%. Other activities, such as maintenance, of ten were carried out concurrently with refueling. lioweve r,

in general, it was not feasible to prorate the outage time to other than the reactor system and fuel elements.

The reactor coolant system required 5132 hours0.0594 days 1.426 hours 0.00849 weeks 0.00195 months . The dominant component was pipes and fittings which required 2956 hours0.0342 days 0.821 hours 0.00489 weeks 0.00112 months . Dresden 3 installed a new feedwater sparger which accounted for 1705 hcurs.

1 The instrumentation and controls system required 2374 hours0.0275 days 0.659 hours 0.00393 weeks 9.03307e-4 months which was primarily due to local power range monitor vibration problems at llatch 1, Peach Bottom 2, and Vermont Yankee.

The steam and power system required 1498 hours0.0173 days 0.416 hours 0.00248 weeks 5.69989e-4 months , the engineered safety features required 775 hours0.00897 days 0.215 hours 0.00128 weeks 2.948875e-4 months , and the electric power and radwaste systems combined accounted for 261 hours0.00302 days 0.0725 hours 4.315476e-4 weeks 9.93105e-5 months .

3.2.6 Pressurized Water Reactors Forced Outages Forced outages in PURs accounted for 43% of the toal outage time, i.e.,

24,197 of 56,926 hours0.0107 days 0.257 hours 0.00153 weeks 3.52343e-4 months . The largest portion of the forced outage time was the result of problems with the steam and power system. This includes the turbines which accounted for 5693 hours0.0659 days 1.581 hours 0.00941 weeks 0.00217 months (10%), heat exchangers, which accounted for 4740 hours0.0549 days 1.317 hours 0.00784 weeks 0.0018 months (8%), valves (3%), shock suppressors (1%), generators (1%), instrumentation and controls (1%), pumps (1%), and various others, another 1%.

The turbine outage time was primarily due to problems at Rancho Seco which had 4438 hours0.0514 days 1.233 hours 0.00734 weeks 0.00169 months of out-age due to turbines. The outage time due to heat exchanger problems was principally due to Palisades, which accounted for 2208 hours0.0256 days 0.613 hours 0.00365 weeks 8.40144e-4 months .

Problems with the reactor coolant system accounted for 5993 hours0.0694 days 1.665 hours 0.00991 weeks 0.00228 months of outage time.

The dominant components were pumps, accounting for 2997 hours0.0347 days 0.833 hours 0.00496 weeks 0.00114 months , and valves, accounting for 2292 hours0.0265 days 0.637 hours 0.00379 weeks 8.72106e-4 months . The reactor system accounted for 1487 hours0.0172 days 0.413 hours 0.00246 weeks 5.658035e-4 months of which the major component involved was control rod drive mechanisms, accounting for 1053 hours0.0122 days 0.293 hours 0.00174 weeks 4.006665e-4 months . The Palisades plant required 527 hours0.0061 days 0.146 hours 8.713624e-4 weeks 2.005235e-4 months for this component. bl

i l

l The electric power system accounted for 880 hours0.0102 days 0.244 hours 0.00146 weeks 3.3484e-4 months , and the auxiliary process system accounted for 379 hours0.00439 days 0.105 hours 6.266534e-4 weeks 1.442095e-4 months . The 857 hours0.00992 days 0.238 hours 0.00142 weeks 3.260885e-4 months listed as others include the following: engineered safety features - 347 hours0.00402 days 0.0964 hours 5.737434e-4 weeks 1.320335e-4 months , instrumentation and controls -

286 hours0.00331 days 0.0794 hours 4.728836e-4 weeks 1.08823e-4 months , auxiliary water system - 219 hours0.00253 days 0.0608 hours 3.621032e-4 weeks 8.33295e-5 months , and other auxiliary systems -

3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months .

Scheduled Outages Scheduled outages in PWRs totaled 32,729 hours0.00844 days 0.203 hours 0.00121 weeks 2.773845e-4 months or 57%. The reactor system ac-counted for 19,534 hours0.00618 days 0.148 hours 8.829365e-4 weeks 2.03187e-4 months , of which 18,525 hours0.00608 days 0.146 hours 8.680556e-4 weeks 1.997625e-4 months was for refueling. The steam and power system required 6474 hours0.0749 days 1.798 hours 0.0107 weeks 0.00246 months , and the dominant conponent was heat ex-changers which accounted for 4728 hours0.0547 days 1.313 hours 0.00782 weeks 0.0018 months . The reactor coolant system accounted for 5672 hours0.0656 days 1.576 hours 0.00938 weeks 0.00216 months , with pumps accounting for 3453 hours0.04 days 0.959 hours 0.00571 weeks 0.00131 months .

The engineered safety features required 524 hours0.00606 days 0.146 hours 8.664021e-4 weeks 1.99382e-4 months and various other systems accounted for the remaining 525 hours0.00608 days 0.146 hours 8.680556e-4 weeks 1.997625e-4 months .

3.2.7 Observations on BWR and PWR Outages Forced Outages Twenty-three BWR plants experienced 33,487 hours0.00564 days 0.135 hours 8.052249e-4 weeks 1.853035e-4 months of forced outage; an overall average of 1456 hours0.0169 days 0.404 hours 0.00241 weeks 5.54008e-4 months per plant.

Twenty-eight PWR plants experienced 24,197 hours0.00228 days 0.0547 hours 3.257275e-4 weeks 7.49585e-5 months of forced outage - an overall average of 864 hours0.01 days 0.24 hours 0.00143 weeks 3.28752e-4 months per plant.

Additional insight as to the relative outages in BWRs and PWRs may be obtained by using the data in Tables 3-9 and 3-10, and comparing the outage percentage and the average number of hours per plant. This is done below where a listed component for either reactor type contributed 1% or more of the total outage time.

The dominant component contributing to PWR forced outage time was turbines accounting for 5693 hours0.0659 days 1.581 hours 0.00941 weeks 0.00217 months or 203 hours0.00235 days 0.0564 hours 3.356481e-4 weeks 7.72415e-5 months per plant.

This was followed closely by heat exchangers with 4740 hours0.0549 days 1.317 hours 0.00784 weeks 0.0018 months or 169 hours0.00196 days 0.0469 hours 2.794312e-4 weeks 6.43045e-5 months per plant. At BWRs, a dispropor-tionate amount of time was attributed to electrical conductors because of the fire which occurred at Browns Ferry, shutting down two reactor units for a combined total of 13,656 hours0.00759 days 0.182 hours 0.00108 weeks 2.49608e-4 months .

The second most dominant component at BWRs was pipes and fittings with 3769 i

hours or 164 hours0.0019 days 0.0456 hours 2.71164e-4 weeks 6.2402e-5 months per plant, followed closely by pumps with 130 hours0.0015 days 0.0361 hours 2.149471e-4 weeks 4.9465e-5 months per plant.

i l \\

L

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PWR BNR l

Outage System Component AVE Avg Type hrs hrs i

Forced Reactor Control Rod Drive 2

38 Reactor Pumps 5

107 5

130 Coolant Valves 4

82 2

74 Pipes & Fittings 1

21 6

164 Steam &

Turbines 10 203 Power IIcat Exchangers 8

169 1

40 valves 3

54 Shock Suppressors 1

22 Generators 1

21 Instrumentation and Control 1

14 Pumps 1

14 Pipes & Fittings 1

1 18 Electric Electrical Power Conductors 21 596 Trans fo rmers 2

62 Scheduled Outages The 23 BWRs had 31,490 hours0.00567 days 0.136 hours 8.101852e-4 weeks 1.86445e-4 months of scheduled outage time for an average of 1369 hours0.0158 days 0.38 hours 0.00226 weeks 5.209045e-4 months per plant. The 28 PWRs accumulated 32,729 hours0.00844 days 0.203 hours 0.00121 weeks 2.773845e-4 months for an average of 1169 hours0.0135 days 0.325 hours 0.00193 weeks 4.448045e-4 months per plant. The scheduled outages in the two types of reactors are compared below on the basis of percent outage and average number of hours per plant.

The comparison is made where a listed component for either reactor type contributed 1% or more of the total outage time.

Obviously fuel elements, the component involved in refuelings, was the dominant component at both types of reactors. The percentage of outage time was nearly the same, but on the average BWRs required 256 hours0.00296 days 0.0711 hours 4.232804e-4 weeks 9.7408e-5 months (39%) more than PWRs.

Other than fuel elements, the dominant component at PWRs was heat exchangers requiring 8% of the total outage time, followed closely by pumps, requiring 6%.

At BWRs the dominant component was pipes and fittings, requiring 5% of the total outage time.

-38a -

A

f 3

i t

PWR BWR i

Outage 9

System Component Type Avg Avg 3

?

h rs hrs Scheduled Reactor Fuel Elements 33 662 32 918 Control Rod Drives 1

20

<1 Re ac to r Pumps 6

123 Coolant Valves 1

26 Pipes & Fittings 4

108 Electrical Conductor 1

37 Valves 1

28 Steam &

llent Exchanger 8

169 1

25 Power Turbines 1

32 Pipes & Fit tings 1

13 Enginee red Pipes & Fittings 2

54 Sa fe ty Fe at u re s l

3.2.8 Summary During 1975, the 23 operating PWRs experienced an average of 2825 hours0.0327 days 0.785 hours 0.00467 weeks 0.00107 months of outage time compared to an average of 2033 hours0.0235 days 0.565 hours 0.00336 weeks 7.735565e-4 months for the 28 operating PWRs.

The percent forced outage at BWRs was 52% compared to 43% at PWRs.

This was due primarily to the Browns Ferry fire which disabled two units and accounted l

for 21% of the total outage time accumulated at BWRs.

The effect of the fire is also reflected in the percent scheduled outage with 48% for BWRs, while at PWRs it is 57%.

At PWRs, the primary cause of forced outages was equipment f ailures, wh ile at BWRs the primary cause was operational error.

Again, this is due to the Browns Ferry fire which was started by a candle held by a techniciar. checking containment penetration leakage. Equipment failures accounted for 21% of the total outage t ime a t BWRs.

s Refueling was the primary cause of scheduled outages at both BWRs and PWRs requiring 30% and 33%, respectively, of the total outage time.

Maintenance or testing also accounted for a large percentage of the scheduled outage time at both types of plants. u

NUREG-0227, Partial Draft of Nuclear Power Plant Operating Experience - 1978, Section 3.0, Plant Outages. Portions of NUREG-0483, NUREG-0366 & NUREG-0227 (Plant Operating Experience for 1977,1976 & 1974-75,respectively) Encl

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NUREG-0227, Partial Draft of Nuclear Power Plant Operating Experience - 1978, Section 3.0, Plant Outages. Portions of NUREG-0483, NUREG-0366 & NUREG-0227 (Plant Operating Experience for 1977,1976 & 1974-75,respectively) Encl

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SUMMARY

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