?
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.
90
Excellence
#2 of 93
Top Quartile
?
Current reactor power level from the most recent NRC daily report.
100%
Power
ONLINE
?
Days of continuous operation since the last outage ended. Ranked against all operating units.
493
Current Run
days
#14 of 95
Top Quartile
?
Longest recorded period of continuous operation between outages.
547
Record Run
days
#66 of 95
Mid Quartile
?
Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (468 days for this 18-month cycle unit) with no trips to 0% power.
12
B2B Runs
Active: 490 days
#4 of 87
Top Quartile
?
Lifetime capacity factor: average power level across all recorded days (100% = always at full power). Ranked against all NRC-tracked units.
95%
Capacity Factor
#2 of 95
Top Quartile
?
Net electricity actually generated over the most recent 12 months reported by the U.S. Energy Information Administration (Form EIA-923), summed across every unit at this plant. These are authoritative actuals, not an estimate.
19.62 TWh
Net Generation
EIA-923 · 12 mo to 2026-06 · plant total
?
Community rating score (Bayesian-adjusted). Based on 34 votes. Ranked against all rated facilities.
50.7
Rating
34 votes
#56 of 97
Mid Quartile
?
Total NRC-reported scram events (emergency reactor shutdowns). Ranked fleet-wide — fewer scrams = better rank.
4
Scrams
#16 of 94
Top Quartile
?
Years since commercial operation began. License remaining: 20.2 years.
39.1
Operating Age
years
20.2 yrs remaining
Reactor Status Timeline
Online NRC data, Mon to Fri ? Actual daily reactor status from NRC reports (Mon to Fri) and the current state. What is coming -- the utility's published Scheduled outage and NukeWorker's model Projection -- is part of a subscription. Colored by status. How far ahead you can see depends on your plan.Online
Estimated reactivity remaining in Byron 2's current fuel cycle, shown as a stylized fuel rod that drains as the cycle progresses. The cycle starts when the unit returns to power after its most recent refueling outage, and the gauge represents the fraction of that cycle's typical effective full-power days (EFPD) still available. Days at less than 100% power burn fuel proportionally — so a unit with significant downtime (high burn deficit) drains slower and ends with MORE reactivity left, giving operators margin to coast down (extend the cycle by reducing power) instead of refueling on the calendar. The dashed red line near the bottom marks the rough industry coastdown threshold (~15% remaining). Cycle target is the unit's median recent cycle length. Source: NRC daily reactor status reports cross-referenced against scheduled refuel outage history.
Fuel Burn Down Cycle since May 2, 2025
Byron 2 is 490 days into its current fuel cycle with an estimated 8.4% of its fuel left. Its typical cycle runs about 534 days.
Fresh — 100%
Refuel — 0%
8.4% remaining
Coastdown territory
Cycle progress
490 / 534 days
EFPD remaining
45 days
Effective burn
489 EFPD
Burn deficit
1.0 FPD
Byron 2 is in coastdown territory — operators may reduce power to stretch the cycle or accept the calendar refuel date.
Historical Burn-Down (17 completed cycles)
Avg refuel point
3.0% remaining
Avg refuel (3yr)
0.6% remaining
Deepest burn
0.0% (2008-10 → 2010-04)
Most margin
7.8% (2010-05 → 2011-09)
Last 5 cycles at refuel
1%
2017-10
2%
2019-04
0%
2020-10
4%
2022-05
1%
2023-10
~4% coastdown (this unit)
Composite Operational Excellence Score for Byron 2 — average percentile rank across 7 publicly observable metrics in three sub-scores: Reliability (capacity factor, forced outage days, B2B avg streak), Efficiency (fuel utilization, refuel duration), and Discipline (startup duration, scram count). Toggle the time window (3yr / 5yr / Lifetime) to see how this unit's standing shifts. Each dimension percentile-ranked across the active US fleet. Sub-score = average of components. Composite = average of the three sub-scores.
NukeWorker's Operational Excellence Score 5-yr composite · ranks 2 of 93 →
NukeWorker scores Byron 2's operational excellence at 90 out of 100 over the past five years, ranking it 2 of 93 reactors in the active US fleet. The score blends reliability, efficiency, and operating discipline drawn from public performance data.
Time window
5-yr trend:
Stable vs 2025
Compare Byron 2 head-to-head with up to 3 other units.
Compare now
Capacity Factor (365-Day)
100%
Current
100%
365-Day Avg
#6
of 94 plants
Min: 91%
Max: 100%
0 days <80%
ELITE B2B CHAMPION
5+ RUNS CLEAN
3,615 days without a trip
·
12 Career Runs · 6 since last trip
Champion since Feb 2, 2019
Breaker-to-Breaker Runs 12 runs
Breaker-to-breaker runs measure continuous operation between refueling outages using a cycle-adjusted threshold (90% of cycle length minus RFO duration). An active streak means the unit has been running continuously since the last refueling with no trips to 0% power.
Byron 2 has logged 12 breaker-to-breaker runs, continuous stretches from one refueling to the next with no trip to zero power. Its longest ran 545 days, and its runs average 532 days. It is on an active 490-day streak right now.
490
Active Streak (days)
Since 2025-05-02
545
Best Run (days)
B2R22 (2020-10-20) → B2R23 (2022-04-18)
532
Avg Run (days)
★ 5-run breaker-to-breaker
B2R20 → B2R21 → B2R22 → B2R23 → B2R24 → B2R25
All Runs
| 2025-05-02 | Active | 490 days | B2R25 → present |
| 2023-10-27 | 2025-04-14 | 535 days | B2R24 → B2R25 |
| 2022-05-12 | 2023-10-09 | 515 days | B2R23 → B2R24 |
| 2020-10-20 | 2022-04-18 | 545 days | B2R22 → B2R23 |
| 2019-04-24 | 2020-10-05 | 530 days | B2R21 → B2R22 |
| 2017-10-22 | 2019-04-08 | 533 days | B2R20 → B2R21 |
| 2014-10-24 | 2016-04-18 | 542 days | B2R18 → B2R19 |
| 2013-04-30 | 2014-09-29 | 517 days | B2R17 → B2R18 |
| 2008-10-24 | 2010-04-19 | 542 days | B2R14 → B2R15 |
| 2005-10-20 | 2007-04-02 | 529 days | B2R12 → B2R13 |
| 2004-04-09 | 2005-09-26 | 535 days | B2R11 → B2R12 |
| 2002-10-08 | 2004-03-23 | 532 days | B2R10 → B2R11 |
Scram History 4 events since 2011
Automatic and manual reactor scram (emergency shutdown) events reported to the NRC since 2011. Includes event dates, trip type, and average recovery time. Click the title to view the full fleet scram dashboard.
Byron 2 has recorded 4 reactor scrams, or emergency shutdowns, since 2011 (1 automatic, 3 manual). On average the unit was back to full power about 5.3 days after each trip.
Outage Duration Trend
?Scheduled refueling outage durations over time. Green bars are below average, yellow near average, red above. Dashed line shows the plant's historical average. Shorter outages mean better execution.
Byron 2 has completed 18 scheduled refueling outages on record, averaging 21 days each. The most recent, in Apr 2025, ran 18 days.
Power History (12-Month)
?Daily power output as a percentage of rated capacity over the past 365 days. Green segments indicate full power (90%+), yellow shows reduced output, and red indicates significant power reductions or shutdowns.
Over the past 12 months Byron 2 has run at an average of 100% of rated power. On the chart, green stretches are full-power running and dips toward zero mark reduced output or outages.
Outage Days by Year
?Total days spent in outage each year, split by scheduled refueling (blue) and forced/unplanned (red). Lower totals indicate better reliability and outage execution. Hover for details.
Across its recorded history, Byron 2 has spent 371 days in scheduled refueling outages and 34 days in forced or unplanned outages. Taller bars mark the years with the most downtime.
Facility Statistics
Key performance and lifecycle metrics calculated from NRC operational data. Includes operating age, construction timeline, capacity factor, efficiency, generation totals, and reliability records.
Byron 2 has operated for about 39.1 years and averaged a 95% lifetime capacity factor, generating roughly 264.3 TWh of electricity. Its longest unbroken run reached 547 days.
Lifecycle & Tenure
Operating Age: 39.1 Yrs
Build Time: 11.6 Yrs
Lic. Remaining: 20.2 Yrs
Production & Power
Lifetime CF: 95%
Efficiency: 31.2%
Generated: 264.3 TWh
Reliability & Outages
Record Run: 547 Days
Refuelings: 18
Avg Startup: 3.7 Days
NukeWorker Member Ratings 34 votes
Community ratings from NukeWorker members. Vote to share your experience working at this facility. Score uses a Bayesian average that accounts for vote count — facilities with few votes are pulled toward the fleet average, so rankings reflect confidence, not just raw percentages.
Above Average
11 (32%)
Average
11 (32%)
Below Average
12 (35%)
Facility Map
Interactive satellite map showing the facility's geographic location. Marker color indicates current status: green for online, red for offline, orange for reduced power. Click the header to open in Google Maps satellite view.
42.0744, -89.2824
Location & Contact
Physical address, phone number, and website for this facility. Use the directions link to get driving directions via Google Maps.
Phone:
(815) 234-5441
Website:
http://www.exeloncorp.com
Per Diem Rates FY 2026
Per diem covers lodging and meals & incidental expenses (M&IE) for government and contractor travel near this facility. Rates are from GSA for FY 2026.
$110
Lodging/Night
$68
M&IE/Day
$178
Total/Day
Standard Rate, IL
Unemployment Benefits IL
Maximum state unemployment insurance benefits for IL. Actual benefits depend on your earnings history and may be lower than the maximum. Data as of Jan 2026.
$859
Max Weekly
26
Max Weeks
$22,334
Max Total
7-day waiting period before benefits begin
Jobs at Byron 17 active
Active job listings posted for this specific facility on the NukeWorker job board. Click a job title for details, or the header to see them all.
More Jobs in IL 154 active
Active nuclear industry job listings in IL from the NukeWorker job board. Click a job title for full details, or click the header to search all jobs in this state.
Photos
Photos of this facility from the NukeWorker photo gallery. Click the header or any photo to browse the full album.
Ownership & Construction
The utility or company that owns and operates the facility, the architect-engineer responsible for plant design, and the primary construction contractor. Click names to view all facilities by that entity on the map.
CEG
Constellation Energy Corporation
NasdaqGS
$298.96
▲ +13.91 (+4.88%)
Previous Close
285.05
Day's Range
284.04 – 299.73
52-Week Range
228.63 – 412.70
Volume
2,898,472
Delayed quote as of Sep 4, 2026 4:00 PM ET.
Source: Yahoo Finance.
Full quote on Yahoo Finance
Technical Specs
Reactor design specifications including type (PWR/BWR), containment design, nuclear steam supply system manufacturer, thermal and electrical power ratings, and current operational status.
Reactor Type:
PWR
Containment:
PWR-DRYAMB
NSS Supplier:
WEST 4LP
Thermal Power:
3645 MWt
Net Capacity:
1136 MWe
Efficiency:
31.2%
Status:
Operating
Licensing
NRC licensing history including docket number, license type and number, construction permit date, operating license issuance, commercial operation date, license renewal, and expiration date.
Docket #:
05000455
License #:
NPF-66
License Type:
OL-FP
Const. Permit:
1975-12-31
Operating Lic:
1987-01-30
Commercial Op:
1987-08-02
License Renewed:
2015-11-19
License Exp:
2046-11-06
Market & Region
EIA market and grid-region classifications: NERC reliability region, U.S. Census region, balancing authority responsible for grid operations, and whether the unit operates as a rate-regulated utility or a competitive merchant generator. Hover any value for the full name.
NERC Region:
RFC
— Reliability First Corporation
Census Region:
ENC
— East North Central
Balancing Authority:
PJM
— PJM Interconnection (ISO/RTO)
Market Structure:
Merchant
— Competitive generator selling into wholesale markets