Calvert Cliffs 2 - Status & History

Comprehensive reactor performance metrics, cycle analysis, and historical outage data.

Plant Info Outage History Daily Power Log
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Composite Operational Excellence Score (0-100) — average percentile rank across 7 dimensions in three sub-scores: Reliability (capacity factor, forced outage days, B2B avg streak), Efficiency (fuel utilization, refuel duration), and Discipline (startup duration, scram count). 5-year window. Higher = more operationally excellent. Click to see the full breakdown.
54
Excellence
#37 of 94 ↓20
Mid Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
414
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2019-03-15 to 2021-03-01).
717
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (619 days for this 24-month cycle unit) with no trips to 0% power.
4
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
93.9%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
14
Outages
since 1999
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Average time from first power generation (>0%) to sustained full power (≥95% for 2+ days) across the last 3 scheduled outages. Click to compare against the fleet on the Operator Efficiency Leaderboard.
2.7
Avg Startup
days (last 3)
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Average fuel utilization — percent of the designed fuel cycle that this unit consumes before refueling, derived from the historical burn-down trajectory. Higher = more efficient operator (refuels with less margin remaining; closer to coastdown). Computed as 100% minus the unit's average refuel-point fuel %, using the last 3 years where available, otherwise lifetime average. Click to compare against the fleet on the Operator Efficiency Leaderboard.
97.4%
Fuel Utilization
3yr avg
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NukeWorker's Operational Excellence Score is a composite 0–100 ranking of every active US nuclear unit across 7 publicly observable performance metrics, grouped into three sub-scores:
• Reliability — capacity factor, forced outage days, B2B avg streak
• Efficiency — fuel utilization, refuel duration
• Discipline — startup duration, scram count
Each unit's metric is converted to a percentile across the active fleet. Sub-score = average of its components; composite = average of the three sub-scores. Use the time-window toggle below to switch between 3yr / 5yr / lifetime.
Time window — change how far back we look
NukeWorker's
Operational
Excellence Score
54/100
Mid Quartile · #37/94
5-year window

Calvert Cliffs 2 ranks #37 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: B2B Avg Streak (93th percentile). Weakest: Scrams (5-year) (1th percentile).

Reliability
75
Capacity factor + Forced outages + B2B streaks
Efficiency
45
Fuel utilization + Refuel duration
Discipline
42
Startup duration + Scram count
Cohort Rankings apples-to-apples comparison within each peer group
Reactor type: #25 of 61 PWR
Containment: #20 of 48 Dry Ambient (PWR)
Cycle length: #18 of 40 24-month cycle
Fleet rank above (37 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor 85th
94.9% (higher better, Reliability)
Forced Outage Days/yr 46th
4.0d (lower better, Reliability)
B2B Avg Streak 93th
707d (higher better, Reliability)
Fuel Utilization 31th
97.2% (higher better, Efficiency)
Refuel Duration 60th
30d (lower better, Efficiency)
Startup Duration 83th
3.3d (lower better, Discipline)
Scrams (5-year) 1th
1.4/yr (lower better, Discipline)

Each dimension's percentile is computed across the active US fleet (94 units with sufficient history). Sub-score = average of its component percentiles. Composite = average of the three sub-scores. 5-year window. View full leaderboard →

Methodology

NukeWorker's Operational Excellence Score is a composite ranking that combines 7 publicly observable performance metrics into a single 0-100 number per US nuclear unit.

How it's computed: Each unit's raw value is converted to a percentile (0-100) within the 94 active US units that have at least 2 completed refueling cycles. The 7 percentiles are averaged into 3 sub-scores (Reliability, Efficiency, Discipline), and those are averaged into the final composite.

Active window — 5-year:

  • Reliability — Capacity factor (5yr), forced outage days/yr (5yr), B2B avg streak (lifetime)
  • Efficiency — in-cycle fuel utilization (3yr), median refuel duration (5yr)
  • Discipline — robust mean startup duration, scrams/yr (5yr, annualised)

Cohort rankings: alongside the fleet rank, each unit gets ranked within its reactor type (PWR/BWR), containment design (Ice Condenser, Mark I, etc.), and cycle length (12/18/24-month). Useful for apples-to-apples comparisons.

What's excluded: subjective community ratings, confidential INPO ratings, financial metrics. We only use publicly available NRC + cycle data.

Why three windows? 5yr (default) is the industry standard. 3yr captures recent operational changes and post-pandemic recovery. Lifetime gives newer units a fair comparison and reveals long-term consistency.

Edge cases: units with fewer than 2 cycles (e.g., Vogtle 4) show "Provisional". Decommissioned units excluded.

Refresh cadence: recomputed daily. Each window cached separately.

A data-derived proxy for operational performance; not affiliated with INPO. INPO ratings are confidential and qualitative — ours is public and quantitative.

5-yr trend: 2021: 75/100 (#16/93)2022: 62/100 (#28/92)2023: 58/100 (#30/92)2024: 54/100 (#38/93)2025: 52/100 (#37/94)2026: 45/100 (#57/94) ↓ -6.5 pts vs 2025
Compare Calvert Cliffs 2 head-to-head with up to 3 other units. Compare now
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Duration of each outage in days, shown chronologically. Green bars are scheduled refueling outages, red bars are forced/unscheduled. The orange dashed line marks the average duration. Extended outages (>180 days) and D&D periods are excluded.

Outage Duration Trend

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Days between consecutive scheduled refueling outage starts, showing operating cycle regularity. The purple dashed line marks the average cycle length. Most U.S. reactors operate on 18-month (547 day) or 24-month (730 day) cycles.

Cycle Length History

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Time in days from first power generation (>0%) to sustained full power (≥95% for 2+ consecutive days) after each scheduled refueling outage. The dashed line marks the average. Includes startup testing holds and power dips.

Startup Duration Trend

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Estimated fuel remaining in the current cycle, expressed as a percentage of the unit's typical cycle. Starts at 100% when the unit returns to power post-refuel and drops as full-power-days are burned. Days at reduced power burn fuel proportionally — so a unit with significant downtime (high burn deficit) drops slower and ends up with MORE fuel left than its calendar position would suggest. Coastdown threshold around 15%. Toggle to overlay past cycles on a normalized "days into cycle" axis to see how aggressively this unit historically burns down before refuel.

Fuel Burn Down Cycle since Mar 28, 2025

42.4% remaining 411 / 713 days 0.6 FPD margin
Avg refuel: 4.1% Avg refuel (3yr): 2.6% Deepest burn: 0.3% (2019-03 → 2021-03) Most margin: 11.3% (2001-05 → 2003-02)
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Monthly capacity factor with outage events overlaid as red bands. Green bars show average power level per month. Toggle to Daily view for raw daily data.

Power History

Type ⇅ Actual Start ⇅ Actual End ⇅ Duration ⇅ Days Online ⇅ Scheduled Delta
Scheduled
2025-02-24 2025-03-26 31 135d 2025-02-17 +7d
Scram # 57372
2024-10-11 2024-10-12 2 81d - -
Scram # 57233
2024-07-19 2024-07-22 4 145d - -
Scram # 56991
2024-02-25 2024-02-25 1 101d - -
Scram # 56856
2023-11-16 2023-11-16 1 7d - -
Scram # 56839
2023-11-08 2023-11-09 2 241d - -
Scheduled
2023-02-20 2023-03-12 21 155d 2023-02-13 +7d
Unscheduled
2022-09-14 2022-09-18 5 252d - -
Scram # 55684
2022-01-04 2022-01-05 2 43d - -
Scram # 55597
2021-11-22 2021-11-22 1 244d - -
Scheduled
2021-03-01 2021-03-23 23 717d 2021-03-01 0d
Scheduled
2019-02-18 2019-03-15 26 715d 2019-02-18 0d
Scheduled
2017-02-13 2017-03-05 21 71d 2017-02-13 0d
Scram # 52406
2016-12-04 2016-12-04 1 364d - -
Scram # 51577
2015-12-02 2015-12-06 5 237d - -
Scram # 50961
2015-04-08 2015-04-09 2 28d - -
Scram # 50961
2015-04-08 2015-04-09 2 1d - -
Scheduled
2015-02-16 2015-03-11 24 387d 2015-02-16 0d
Scram # 49754
2014-01-22 2014-01-25 4 135d - -
Scram # 49754
2014-01-22 2014-01-25 4 3d - -
Unscheduled
2013-09-06 2013-09-09 4 107d - -
Scram # 49054
2013-05-22 2013-05-22 1 11d - -
Scram # 49012
2013-05-09 2013-05-11 3 46d - -
Scheduled
2013-02-18 2013-03-24 35 707d 2013-02-17 +1d
Scheduled
2011-02-14 2011-03-14 29 352d 2011-02-20 -6d
Unscheduled
2010-02-19 2010-02-27 9 340d - -
Scheduled
2009-02-23 2009-03-16 22 693d 2009-02-22 +1d
Scheduled
2007-02-26 2007-04-02 36 98d 2007-02-25 +1d
Unscheduled
2006-11-16 2006-11-20 5 612d - -
Scheduled
2005-02-23 2005-03-14 20 395d 2005-02-22 +1d
Unscheduled
2004-01-24 2004-01-25 2 240d - -
Unscheduled
2003-05-29 2003-05-29 1 38d - -
Scheduled SGR/Major
2003-02-15 2003-04-21 66 476d 2003-02-15 0d
Unscheduled
2001-10-26 2001-10-27 2 165d - -
Scheduled
2001-03-17 2001-05-14 59 386d 2001-03-17 0d
Unscheduled
2000-02-19 2000-02-25 7 289d - -
Scheduled
1999-03-13 1999-05-06 55 - 1999-03-13 0d
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