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

NYISO

25.4% offline · 844 MW

MW in Refueling Now

1,996 MW

2 units at a full outage

MW at Risk · Next 60 Days

megawatts due off line within 60 days

Biggest 30-day Mover

NYISO

availability ▼ 23.4 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

Vertically Integrated 8u

Southern

6,893 MW

85.3% available ↗ 97 MW DoD

vs 7d avg−625 MW (−8.3%)

vs 1 yr ago██

Fleet record ██ ██

Fall 26 avg offline 125 MW

What to watch Active: Vogtle 2 · −1,152 MW since Aug 22, 2026

Vertically Integrated 3u

SRP

3,937 MW

100.0% available 0 MW DoD

vs 7d avg+7 MW (+0.2%)

vs 1 yr ago██

Fleet record ██ ██

Fall 26 avg offline 3 MW

What to watch All units at full power

ISO / RTO 4u

NYISO

2,485 MW

74.6% available 0 MW DoD

vs 7d avg−566 MW (−18.6%)

vs 1 yr ago██

Fleet record ██ ██

Fall 26 avg offline 81 MW

What to watch Active: FitzPatrick · −844 MW since Jul 28, 2026

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 days

NYISO

↘ −23.4 pp

Southern

↘ −14.7 pp

SRP

↗ +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
NYISO	ISO/RTO	4	74.6%	844	25.4%	soft	▼ 23.4
Southern	Non-ISO	8	85.3%	1,187	14.7%	—	▼ 14.7
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 plans

Ontario (IESO) separate fleet

Ontario detail

MW 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.