Millstone Nuclear Power Plant

The Millstone Nuclear Power Station is the only nuclear power plant in Connecticut^[2] and the only multi-unit nuclear plant in New England. It is located at a former quarry (from which it takes its name) in Waterford. With a total capacity of over 2 GW, the station produces enough electricity to power about 2 million homes. The operation of the Millstone Power Station supports more than 3,900 jobs, and generates the equivalent of over half the electricity consumed in Connecticut.^[3]

Millstone Power Station
Country	United States
Location	Waterford, New London County, Connecticut
Coordinates	41°18′37.9614″N 72°10′3.7194″W
Status	Operational
Construction began	Unit 1: May 1, 1966 Unit 2: November 1, 1969 Unit 3: August 9, 1974
Commission date	Unit 1: March 1, 1971 Unit 2: December 26, 1975 Unit 3: April 23, 1986
Decommission date	Unit 1: July 1, 1998
Construction cost	$8.845 billion (2007 USD, Units 2–3 only)[1]
Owner	Dominion Energy
Operator	Dominion Energy
Nuclear power station
Reactor type	Unit 1: BWR Units 2–3: PWR
Reactor supplier	Unit 1: General Electric Unit 2: Combustion Engineering Unit 3: Westinghouse
Cooling source	Long Island Sound
Thermal capacity	1 × 2011 MWth (decommissioned) 1 × 2700 MWth 1 × 3650 MWth
Power generation
Units operational	1 × 869 MW 1 × 1229 MW
Make and model	Unit 1: BWR-4 (Mark 1) Unit 2: CE 2-loop (DRYAMB) Unit 3: WH 4-loop (DRYSUB)
Units decommissioned	1 × 641 MW
Nameplate capacity	2098 MW
Capacity factor	89.99% (2017) 71.23% (lifetime)
Annual net output	17,216 GWh (2021)
External links
Website	Millstone Power Station
Commons	Related media on Commons

The Millstone site covers about 500 acres (2 km²).^[4] The power generation complex was built by a consortium of utilities, using Long Island Sound as a source of secondary side cooling. Millstone Units 2 and 3, both pressurized water reactors (one from Westinghouse and one from Combustion Engineering), were sold to Dominion Resources by Northeast Utilities in 2000 and continue to operate.^[5]

The plant has had numerous safety-related shutdowns and at times been placed on enhanced examination status by the Nuclear Regulatory Commission.^[6][7] In 1999, Northeast Utilities, the plant's operator at the time, agreed to pay $10 million in fines for 25 counts of lying to federal investigators and for having falsified environmental reports. Its subsidiary, Northeast Nuclear Energy Company, paid an additional $5 million for having made 19 false statements to federal regulators regarding the promotion of unqualified plant operators between 1992 and 1996.^[8][9]

On November 28, 2005, after a 22-month application and evaluation process, Millstone was granted a 20-year license extension for both units 2 and 3 by the NRC.^[10]

Licensing history and milestones

Work being performed on the containment structure at the Millstone Nuclear Power Plant.

Unit 1

Millstone 1 was a General Electric boiling water reactor, producing 660 MWe, shut down in November 1995 before being permanently closed in July 1998.

• Construction permit issued: May 19, 1966^[11]
• Final safety analysis report filed: November 1, 1968
• Provisional operating license issued: October 7, 1970^[12][4]
• Full term operating license issued: October 31, 1986
• Full power license: October 7, 1970^[4]
• Initial criticality: October 26, 1970^[13]
• Synchronized to the grid: November 1970
• Commercial operation: December 28, 1970
• 100% power: January 6, 1971
• The U.S. Nuclear Regulatory Commission began a safety investigation relating to refueling procedures, based on information provided by George Galatis, a senior nuclear engineer, 1995.^[14]
• Leaking valve forced shutdown multiple equipment failures detected: February 20, 1996
• Permanently ceased operations: July 21, 1998^[15]

Unit 2

Millstone 2 is a Combustion Engineering pressurized water reactor plant built in the 1970s, and has a maximum power output of 2700 thermal megawatts, or MWth (870 MWe). It has 2 steam generators, and 4 reactor cooling pumps. It is^[when?] undergoing an upgrade to its safe shutdown system which already met NRC standards. During its refueling outage in October 2006, the operator installed a new pressurizer.

• Construction permit issued: December 11, 1970
• Final safety analysis report filed: August 15, 1972
• Full term operating licensing issued: September 26, 1975
• Full power license: September 26, 1975
• Initial criticality: January 17, 1975^[13]
• Commercial operation: December 26, 1975
• 100% power: March 20, 1976
• "Stretch power": June 25, 1979
• Operating license extension requested: December 22, 1986
• Operating license extension issued: January 12, 1988
• Full term operating license expires: December 11, 2010
• Operating license expires: July 31, 2015
• Extended operating license expires: July 31, 2035

Unit 3

Millstone 3 is a Westinghouse plant that started operating in 1986, and has a maximum power output of 3650 MWth (1260 MWe). In the summer of 2008, the NRC approved a power uprate for Unit 3 that increased its electrical output 7.006% to 3650 MWth (1230 MWe). The increase took effect by the end of 2008.^[16]

• Construction permit issued: August 9, 1974^[4]
• Initial criticality: January 23, 1986
• Commercial operation: April 23, 1986
• Operating license expires: November 25, 2025
• Extended operating license expires: November 25, 2045

Electricity Production

Generation (MWh) of Millstone Power Station^[17]

Year	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Annual (Total)
2001	1,366,126	620,610	643,005	1,368,619	1,342,326	1,441,469	1,464,628	1,396,871	1,435,437	1,491,469	1,372,527	1,484,680	15,427,767
2002	1,477,462	1,020,136	850,042	1,159,749	1,497,037	1,421,445	1,484,163	1,292,391	750,180	1,251,934	1,453,640	1,260,093	14,918,272
2003	1,447,607	1,364,927	1,087,699	1,458,326	1,509,611	1,419,320	1,496,738	1,485,570	1,442,531	1,052,843	823,382	1,489,541	16,078,095
2004	1,514,725	1,416,949	1,357,314	669,780	1,198,434	1,466,127	1,500,558	1,494,418	1,455,788	1,514,313	1,435,926	1,514,765	16,539,097
2005	1,517,951	1,371,151	1,512,889	615,298	1,098,080	1,464,341	1,506,553	1,497,980	1,406,057	719,636	1,459,379	1,392,807	15,562,122
2006	1,519,136	1,308,343	1,518,458	1,280,682	1,516,725	1,463,454	1,502,444	1,498,380	1,453,911	959,234	1,055,264	1,513,415	16,589,446
2007	1,413,243	1,365,236	1,510,387	790,130	959,038	1,454,548	1,498,812	1,493,112	1,446,523	1,497,311	1,456,391	1,501,411	16,386,142
2008	1,506,855	1,407,918	1,503,666	923,531	1,032,094	1,394,073	1,463,357	1,484,185	1,440,365	940,798	771,358	1,564,746	15,432,946
2009	1,568,502	1,416,776	1,560,557	1,518,510	1,566,800	1,512,957	1,086,929	1,546,944	1,502,156	1,034,216	1,130,862	1,212,173	16,657,382
2010	1,403,129	1,368,339	1,560,238	918,593	947,990	1,518,345	1,561,523	1,446,144	1,506,738	1,565,484	1,425,006	1,528,775	16,750,304
2011	1,573,286	1,417,144	1,571,839	927,458	1,501,912	1,438,058	1,555,841	1,499,191	1,189,238	858,702	823,268	1,571,900	15,927,837
2012	1,557,888	1,455,944	1,570,928	1,518,162	1,546,933	1,512,620	1,528,126	1,287,047	1,491,488	1,015,837	1,024,275	1,568,639	17,077,887
2013	1,570,408	1,418,239	1,568,407	1,006,680	998,334	1,513,501	1,554,382	1,396,122	1,500,677	1,552,489	1,434,929	1,565,414	17,079,582
2014	1,547,921	1,370,137	1,564,866	984,611	915,374	1,433,769	1,456,260	1,545,219	1,492,737	957,780	1,003,232	1,568,713	15,840,619
2015	1,569,302	1,416,474	1,566,390	1,386,998	1,564,086	1,511,809	1,555,196	1,548,421	1,494,525	963,025	1,278,219	1,556,472	17,410,917
2016	1,395,804	1,453,731	1,553,691	870,970	1,042,398	1,157,289	1,545,157	1,465,939	1,492,559	1,541,912	1,502,398	1,553,644	16,575,492
2017	1,552,802	1,405,299	1,549,445	888,022	1,440,352	1,499,861	1,540,401	1,532,203	1,488,432	974,762	1,069,696	1,558,346	16,499,621
2018	1,562,198	1,408,160	1,557,604	1,503,520	1,550,957	1,500,266	1,538,028	1,528,480	1,397,258	907,772	887,693	1,539,556	16,881,492
2019	1,556,867	1,406,987	1,549,156	755,800	1,035,404	1,502,805	1,537,561	1,535,968	1,486,081	1,540,270	1,500,314	1,326,185	16,733,398
2020	1,555,862	1,460,856	1,559,892	985,158	912,169	1,380,637	1,544,050	1,511,859	1,492,689	664,016	1,135,412	1,512,255	15,714,855
2021	1,399,646	1,413,362	1,565,742	1,513,226	1,561,563	1,261,548	1,547,127	1,527,962	1,488,664	1,036,856	1,341,626	1,559,187	17,216,509
2022	1,423,440	1,408,875	1,556,974	802,500	644,649	1,385,138	1,551,414	1,546,783	1,494,689	1,557,614	1,519,821	1,572,270	16,464,167
2023	1,526,170	1,360,879	1,556,546	999,245	868,981	26,108	1,443,004	1,542,360	1,311,751	1,159,993	624,914	1,249,507	13,669,458
2024	1,263,781	1,466,547	1,568,155	1,517,438									5,815,921
2025

Safety and environmental events

In December 1977, two hydrogen explosions occurred at the plant.^[18][19] The second explosion injured one man, who required hospitalization.^[20]

In October 1990, operator error during a routine test caused a shutdown of unit 2.^[6]

In September 1991, twenty reactor operators failed required licensing examinations. The shortfall of licensed operators necessitated a shutdown of unit 1 until March 1992.^[6]

In 1995 the U.S. Nuclear Regulatory Commission began a safety investigation relating to refueling procedures at Millstone unit 1, based on information provided by George Galatis, a senior nuclear engineer.^[14]

On February 26, 1996, a leaking valve forced the shutdown of units 1 and 2. Multiple equipment failures were found.^[21][22] Time magazine featured the plant on its cover, calling its operator a "rogue utility", and the Nuclear Regulatory Commission singled out Millstone for additional attention.^[6][7] Also in 1996, the plant released one gallon per hour of hydrazine into Long Island Sound. The plant's operators were convicted in 1999 for falsifying environmental records related to the hydrazine release.^[9]

Following the Time article and the subsequent shutdown of all reactors, unit 2 restarted May 11, 1999 and unit 3 restarted July 1, 1998. Unit 1 was never restarted as the cost of remedying numerous safety issues was too high.^[23]

In 2002 Millstone's operators were fined $288,000 for failing to have properly accounted for two uranium fuel rod components that had been misplaced 30 years earlier in 1972.^[24]

On April 17, 2005, Millstone unit 3 safely shut down without incident when a circuit board monitoring a steam pressure line short-circuited, which caused the board to malfunction and indicate an unsafe drop in pressure in the reactor's steam system, when in reality there was no drop in steam pressure. The cause was attributed to tin whiskers on the board.^[25] In response to this event, Millstone implemented a procedure to inspect for these whiskers at every refueling outage, or 18 months.^[26]

In September, 2009, unit 2 shut down when an electrical storm caused power fluctuations. When workers tried to restart the unit, they discovered a small leak in the reactor coolant pump.^[27] On December 21, 2009 the Unit 3 reactor tripped and shut down for longer than 72 hours.^[28] On July 27, 2009, the Unit 2 reactor tripped and shut down for longer than 72 hours. On August 9, 2013, the Unit 3 reactor tripped and shut down due to a malfunction. In 2016, unit 3 was shut down following a hydrogen gas leak.^[29]

Surrounding population

The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles (16 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity.^[30]

The 2010 U.S. population within 10 miles (16 km) of Millstone was 123,482, an increase of 29.5 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within 50 miles (80 km) was 2,996,756, an increase of 9.5 percent since 2000. Cities within 50 miles include Hartford (41 miles to city center) and New Haven (43 miles to city center).^[31]

Seismic risk

The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Millstone was 1 in 90,909 for Reactor 2 and 1 in 66,667 for Reactor 3, according to an NRC study published in August 2010.^[32][33]

See also

• Connecticut portal
• Energy portal
• Nuclear technology portal

• List of largest power stations in the United States
• Lelan Sillin, Jr.

References

1. "EIA - State Nuclear Profiles". www.eia.gov. Retrieved 3 October 2017.
2. "Facilities by NRC Region or State / Connecticut". United States Nuclear Regulatory Commission. March 9, 2021. Retrieved September 23, 2022.
3. "Millstone Power Station | Dominion Energy".
4. Millstone Nuclear Power Station Unit 3, Operation: Environmental Impact Statement. 1985. pp. 19–.
5. Spinella, Stan (January 26, 2021). "Dominion officials discuss future of Millstone Nuclear Power Station". The Day. Retrieved June 21, 2022.
6. Paul W. MacAvoy; Jean W. Rosenthal (2005). Corporate Profit and Nuclear Safety: Strategy at Northeast Utilities in the 1990s. Princeton University Press. pp. 48–. ISBN 0-691-11994-5.
7. National Academy of Engineering (16 September 2004). Accident Precursor Analysis and Management: Reducing Technological Risk Through Diligence. National Academies Press. pp. 24–. ISBN 978-0-309-09216-6.
8. Hechinger, John (28 September 1999). "Northeast Utilities Pleads Guilty To Polluting at Millstone Plant". The Wall Street Journal. Retrieved 18 December 2016.
9. Allen, Mike (28 September 1999). "A Record U.S. Fine at a Connecticut Nuclear Plant". The New York Times. Retrieved 18 December 2016.
10. "Millstone Nuclear Power Station, Units 2 and 3 - License Renewal Application". U.S. Nuclear Regulatory Commission. November 28, 2005. Retrieved June 21, 2022.
11. Millstone Nuclear Power Station, Unit 2, Construction: Environmental Impact Statement. 1973.
12. Transactions of the American Nuclear Society. Academic Press. 1972.
13. Janette Sherman (1 May 2014). Life's Delicate Balance: Causes and Prevention of Breast Cancer. Taylor & Francis. pp. 73–. ISBN 978-1-135-91406-6.
14. "NRC Failure to Adequately Regulate - Millstone Unit 1" (PDF). U.S. Nuclear Regulatory Commission. December 21, 1995. Archived from the original (PDF) on May 14, 2009. Retrieved June 21, 2022.
15. "Millstone - Unit 1". US NRC. Retrieved 17 December 2016.
16. "NRC Approves Power Uprate for Millstone Nuclear Power Plant" (PDF). U.S. Nuclear Regulatory Commission. August 12, 2008.
17. "Electricity Data Browser". www.eia.gov. Retrieved 2023-01-08.
18. Licensee Contractor and Vendor Inspection Status Report. Office of Inspection and Enforcement, Nuclear Regulatory Commission. 1978.
19. Mother Jones (January 1979). "Mother Jones Magazine". Mother Jones: 18–. ISSN 0362-8841.
20. "Bulletin 78-03: Potential Explosive Gas Mixture Accumulations Associated With BWR Offgas System Operations". Nuclear Regulatory Commission. Retrieved 17 December 2016.
21. Benjamin K. Sovacool; Scott Victor Valentine (16 May 2012). The National Politics of Nuclear Power: Economics, Security, and Governance. Routledge. pp. 260–. ISBN 978-1-136-29437-2.
22. United States. Congress. House. Committee on Commerce. Subcommittee on Energy and Power (1996). Oversight hearing on the Nuclear Regulatory Commission: hearing before the Subcommittee on Energy and Power of the Committee on Commerce, House of Representatives, One Hundred Fourth Congress, second session, September 5, 1996. U.S. Government Printing Office. ISBN 978-0-16-053701-1.
23. Lochbaum, David (24 November 2015). "Longstanding Nuclear Safety Impairments". Union of Concerned Scientists. Retrieved 18 December 2016.
24. Nuclear Regulatory Commission NRC needs to do more to ensure that power plants are effectively controlling spent nuclear fuel: report to Congressional requesters. United States Government Accountability Office. pp. 11–12. ISBN 978-1-4289-3176-3.
25. John X. Wang (25 July 2012). Green Electronics Manufacturing: Creating Environmental Sensible Products. CRC Press. pp. 29–. ISBN 978-1-4398-2669-0.
26. Daddona, Patricia. "Reactor Shutdown: Dominion Learns Big Lesson From A Tiny 'tin Whisker'". The Day. Retrieved June 21, 2022.
27. "Millstone 2 operating again after shutdown". September 2009.
28. "Preliminary Notification of Event or Unusual Occurrence -- PNO-I-09-007" (PDF). nrc.gov. Retrieved 18 December 2016.
29. "Millstone Reactor Shuts Down Due to Hydrogen Gas Leak". nbcconnecticut.com. Retrieved 17 December 2016.
30. "NRC: Backgrounder on Emergency Preparedness for Nuclear Power Plants". Archived from the original on 2006-10-02. Retrieved 2012-03-14.
31. "Nuclear neighbors: Population rises near US reactors". NBC News. 2011-04-14. Retrieved 2024-08-16.
32. "What are the odds? US nuke plants ranked by quake risk". NBC News. 2011-03-16. Retrieved 2024-08-16.
33. "Implications of Updated Probabilistic Seismic Hazard Estimates in Central and Eastern United States on Existing Plants" (PDF). U.S. Nuclear Regulatory Commission. August 23, 2010. Retrieved June 21, 2022.

External links

• Dominion's nuclear page
• DoE Page
• NukeWorker