Market Briefing · updated daily
Markets
Where U.S. nuclear supply is tightest right now, and what is coming off line next. As of Sep 15, 2026 · Updated every morning from the NRC Daily Power Reactor Status Report.
Most-stressed Market
MISO
1.9% offline · 216 MW
MW in Refueling Now
0 MW
0 units at a full outage
MW at Risk · Next 60 Days
megawatts due off line within 60 days
Biggest 30-day Mover
MISO
availability ▲ 3.7 pts
By Market
Available nuclear MW now, the day's move, vs 7-day and a year ago, and the 30-day trend, by balancing authority
ISO / RTO
13u
11,296 MW
98.1% available
↗ 183 MW DoD
vs 7d avg−14 MW (−0.1%)
vs 1 yr ago██
Fall 26 avg offline
587 MW
ISO / RTO
4u
4,986 MW
100.0% available
0 MW DoD
vs 7d avg0 MW (0.0%)
vs 1 yr ago██
Fall 26 avg offline
10 MW
What to watch
All units at full power
Vertically Integrated
3u
3,937 MW
100.0% available
0 MW DoD
vs 7d avg+7 MW (+0.2%)
vs 1 yr ago██
Fall 26 avg offline
3 MW
What to watch
All units at full power
Vertically Integrated
4u
3,570 MW
97.8% available
↘ 79 MW DoD
vs 7d avg−79 MW (−2.2%)
vs 1 yr ago██
Fall 26 avg offline
41 MW
Vertically Integrated
4u
3,593 MW
100.0% available
0 MW DoD
vs 7d avg+40 MW (+1.1%)
vs 1 yr ago██
Fall 26 avg offline
16 MW
What to watch
All units at full power
Available MW = nuclear generating MW now (installed nuclear MW minus what is offline), at the 98% full-power floor. DoD is the change since yesterday; the 30-day spark is the market's availability (% of its nuclear fleet generating). "What to watch" is the largest unit offline now, with the date it went down.
Biggest 30-Day Movers
Signed change in nuclear availability over the last 30 daysMISO
↗ +3.7 pp
FPL
↘ −2.2 pp
ERCOT
↗ +0.0 pp
SRP
↗ +0.0 pp
Duke Progress
↗ +0.0 pp
Change in each market's nuclear availability (generating MW as a share of installed nuclear MW) between 30 days ago and today. Positive points = more nuclear back online.
Most-stressed Markets
By share of nuclear fleet offline, lowest availability first| Market | Type | Units | Availability | MW Offline | % Offline | Grid tomorrow | 30d Δavail |
|---|---|---|---|---|---|---|---|
| FPL | Non-ISO | 4 | 97.8% | 79 | 2.2% | — | ▼ 2.2 |
| MISO | ISO/RTO | 13 | 98.1% | 216 | 1.9% | soft | ▲ 3.7 |
| Duke Progress | Non-ISO | 4 | 100.0% | — | 0.0% | — | ▲ 0.0 |
| ERCOT | ISO/RTO | 4 | 100.0% | — | 0.0% | normal | ▲ 0.0 |
| SRP | Non-ISO | 3 | 100.0% | — | 0.0% | — | ▲ 0.0 |
Availability = nuclear generating MW ÷ installed nuclear MW. "Grid tomorrow" is the day-ahead demand forecast vs the trailing-30-day norm, where a nuclear loss bites hardest. 30d Δavail is the change in the market's nuclear availability over the last 30 days.
Which market is about to be short, and by how much
Which units come off line next, when, and how much capacity is at risk by market (our sourced dates plus model projections) is part of NukeGryd Individual and up. Today's live market stress stays free.
See plansOntario (IESO) separate fleet
Ontario detailMW Offline
3,632 MW
29.9% of the Ontario fleet
Units Offline
4 of 16
Bruce, Darlington, Pickering
Delivering
8,528 MW
of 12,160 MW installed
Resolution
1 hour
vs. once-daily for the U.S. fleet
Ontario supply, for the northeast picture. Ontario is reported as a separate fleet and is never added into the U.S. national figures above. IESO grid-operator market data (MW delivered), not NRC percent-power.