Pilgrim 1
DecommissionedHoltec International·Plymouth, MA·BWR·685 MWe
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Current reactor power level from the most recent NRC daily report.
Shut Down
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Days of continuous operation since the last outage ended. Ranked against all operating units.
2,614
Current Run
days
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Longest recorded period of continuous operation between outages.
2,614
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (614 days for this 24-month cycle unit) with no trips to 0% power.
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B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power). Ranked against all NRC-tracked units.
88.9%
Capacity Factor
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Total NRC-reported scram events (emergency reactor shutdowns). Ranked fleet-wide — fewer scrams = better rank.
13
Scrams
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Years since commercial operation began.
46.5
Operating Age
years
Excellence Score, Records & Plant Facts
About This Site
Written by NukeWorker from public records: facts that do not change. Operator, status and capacity come from the live data elsewhere on this page. Sources: Wikipedia: Pilgrim Nuclear Generating Station.
Pilgrim Nuclear Power Station was in the Manomet section of Plymouth, Plymouth County, Massachusetts, on Cape Cod Bay between Rocky Point and Priscilla Beach.
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Boston Edison built the plant, with Bechtel as constructor. Construction began on August 26, 1968, around a General Electric BWR-3 boiling water reactor with a Mark 1 containment. It connected to the grid on July 19, 1972, and entered commercial operation on December 1, 1972. An emergency shutdown on April 11, 1986 led the NRC to call it one of the worst-run plants in the country. The owner announced in October 2015 that the plant would close, and it was permanently shut down on May 31, 2019.
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.
Pilgrim 1 has operated for about 46.5 years and averaged a 88.9% lifetime capacity factor, generating roughly 110.2 TWh of electricity. Its longest unbroken run reached 2,614 days.
Lifecycle & Tenure
Operating Age: 46.5 Yrs
Build Time: 4.3 Yrs
Lic. Remaining: N/A Yrs
Production & Power
Lifetime CF: 88.9%
Efficiency: 34.3%
Generated: 110.2 TWh
Reliability & Outages
Record Run: 2,614 Days
Refuelings: 11
Avg Startup: 7.1 Days
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.
Ownership, operation and management history
| Date | Change | From | To |
|---|---|---|---|
| Jul 1999 | Sold | Boston Edison | Entergy |
| Aug 26, 2019 | Sold | Entergy | Holtec |
Publicly Traded
No — Privately held
Scram History 13 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.
Pilgrim 1 has recorded 13 reactor scrams, or emergency shutdowns, since 2011 (6 automatic, 7 manual). On average the unit was back to full power about 10.3 days after each trip.
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:
BWR
Containment:
BWR-MARK 1
NSS Supplier:
GE 3
Turbine Supplier:
GENERAL ELECTRIC CO. IAEA
Thermal Power:
1998 MWt
Net Capacity:
685 MWe
Gross Capacity:
711 MWe IAEA
Design Capacity:
655 MWe IAEA
Efficiency:
34.3%
Status:
Decommissioned
Lifetime Output:
193.6 TWh through 2025 IAEA
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 #:
05000293
License #:
DPR-35
License Type:
OL-FP
Const. Permit:
1968-08-26
Construction Start:
1968-08-26 IAEA
Operating Lic:
1972-09-15
First Criticality:
1972-06-16 IAEA
Grid Connection:
1972-07-19 IAEA
Commercial Op:
1972-12-01
License Renewed:
2012-05-29
License Exp:
2012-06-08