A special team of six federal inspectors is investigating the unplanned shutdown of the Pilgrim Nuclear Power Plant in Plymouth. The reactor, which produces about 10 percent of the state’s electricity, lost power during last week’s blizzard and had to rely on generators to run the nuclear plant’s critical safety systems. WBUR’s Bruce Gellerman reports on the shutdown and investigation.
Last month, Entergy began transferring spent fuel from Pilgrim Nuclear Power Station’s overcrowded wet pool to dry cask storage.
Entergy needs to create space in its spent fuel pool so that spent fuel that is removed from the reactor in the future has a place to cool. Two of the three storage casks wereloaded in January, with each cask containing 68 assemblies; the third cask was loaded the first week of February. The casks will be stored onsite at Pilgrim and are likely to remain in Plymouth for an indefinite period of time, as there is no Federal repository for storage of spent nuclear fuel.
The Union of Concerned Scientists, and the Massachusetts and New York Attorneys General offices, believe dry cask storage of spent fuel to be safer than wet pool storage because it is passive and does not require human action to cool the fuel. However, the Nuclear Regulatory Commission, and numerous government and scientific sources, have reported problems with the steel and concrete dry casks Entergy has ordered for spent fuel storage at Pilgrim. Concerns regarding the long-term viability and safety of dry casks have been raised, as well as the potential for stress corrosion cracking due to salt water exposure (with subsequent radioactive release) and vulnerability to terrorist attack.
Dry casks have three components: 1. a metal transfer cask to lift and handle the canister and prevent radioactive shieling of the spent fuel assemblies, 2. a leak-proof metal canister capable of holding 68 boiling water reactor assemblies, and 3. a storage overpack made of steel-encased concrete which provides physical and radiological protection of the metal canister when stored on the dry cask pad. This canister is vented for natural convection to dissipate spent fuel decay heat.
Pilgrim’s dry cask storage facility is located only about 175 feet away from the shoreline of Cape Cod Bay and about 6 feet above FEMA’s flood level. The proximity of the dry casks to the water and the effect of storm surge and sea level rise are worrisome. Pilgrim’s salt water environment may lead to premature stress corrosion cracking of the stainless steel canisters within 30 years – or perhaps sooner – resulting in major radiation releases. The concrete overpacks can also suffer from accelerated aging issues as the result of the coastal factors. Other nuclear power plants, such as San Onofre in Pendleton, California – also located on the water – have documented component failures in similar materials that have occurred in less than 30 years.
Unfortunately, the technology does not exist to inspect even the outside of the stainless steel canisters for cracks once loaded with spent fuel meaning there is no way to know that a stress corrosion crack has occurred. The NRC has given the nuclear industry five years to develop a method for inspecting the outside of the canisters; however, the NRC only plans on requiring inspection of one canister at each nuclear power plant. Even if a method did exist to detect a canister crack, there is no remediation plan if a canister does fail. The technology that is used to repair other stainless steel components cannot be used to repair canisters containing spent nuclear fuel. Per the NRC, if a canister becomes damaged due to a stress corrosion crack, there is no way to repair or replace the canister. Additionally, a canister cannot be transported in a transfer cask if there is a crack.
One potential fuel-handling solution that is currently being considered is the possibility of bringing a cask, or canister, back into the spent fuel pool, where it could be opened and possibly repaired or replaced. However, there is no publicly published documentation that a boiling water reactor dry cask has ever been loaded back into a spent fuel pool containing other assemblies. Temperature differences between the fuel in the dry cask and the spent fuel pool could disturb the properties of the cask, cladding, fuel, and related hardware if the materials were rewetted and rapidly cooled. Reinsertion of dry casks in the wet pool would thermally shock the irradiated fuel rods and cause a steam flash which would harm workers in the facility. Hence, an empty wet pool specifically designated for the reopening of damaged casks would be needed and is currently not available at any nuclear power plant in the country. Technology known as dry (hot cell) transfer has been discussed as an option for handling damaged casks; however, there is no dry handling facility available that is large enough to handle these canisters. Additionally, there is no mobile facility designed for this purpose and designing one may not be feasible.
There are no monitors installed on each cask to measure heat, helium (detection of helium can provide early warning of a problem) and radiation. A daily surveillance of the dry cask passive heat removal system is required to ensure system operability. This can be achieved by either monitoring the casks’ inlet and outlet vent temperatures or performing a visual inspection daily to ensure that the casks’ vents are not blocked. Pilgrim has chosen to perform daily visual inspections to ensure the air inlet and outlet vents do not become blocked and the passive heat removal system remains operable. The NRC expects that thermoluminscent dosimeters will be placed around the storage pad and will be used to monitor radiation on a quarterly to yearly basis. Unfortunately, the dosimeters can only read to a maximum threshold. They cannot provide an immediate reading of radiation.
Though the prospect of storing high-level nuclear waste in Plymouth indefinitely is not a pleasant thought and will never be the right or perfect solution for our town, there are steps that can be taken to do the job right and make dry cask storage as safe as it can be. Moving the dry casks to higher ground and enclosing them within a building offers multiple benefits: 1. increased protection against a salt water environment, storm surge, and sea level rise, 2. prevention of blockage of dry cask ventilation due to ice, snow, mud, and birds’ nests, thereby lowering the chance of a canister overheating, and 3. decreased visibility to potential terrorists, hence decreasing the site’s vulnerability to an attack.
While there is no current method to repair damaged canisters or casks, the addition of heat, helium, and radiation monitors for each cask would provide real-time information which would be invaluable in terms of identifying and responding to a problem with a dry cask. On-site storage of additional overpacks may offer temporary protection should a canister or cask corrosion crack occur.
Ultimately the best solution is to use casks that are not susceptible to cracks, that can be inspected and repaired, and that have early warning monitoring systems that alert us before radiation leaks into the environment.
Despite the concerns related to dry casks, dry cask storage has many advantages over wet pool storage: it does not require mechanical parts or offsite electrical power; does not need human intervention to function properly; and, is not as vulnerable to acts of terrorism. Dry cask storage also reduces the amount of spent fuel in the SFP, meaning there will be fewer releases of radioactivity in the event of an accident. Sadly, significant gains in safety can only be realized through expedited transfer dry cask transfer and resultant thinning of the spent fuel pool, which currently Pilgrim does not plan to do.
Heather Lightner is a registered nurse in Plymouth and president of Concerned Neighbors of Pilgrim, a local, grassroots group focused on safer storage of spent nuclear fuel at Pilgrim Nuclear Power Station. She serves on the Plymouth Nuclear Matters Committee. The opinions expressed here are hers and do not reflect the official position of the NMC.
Pilgrim shut down automatically at 4:05am Tuesday, January 27, 2015 after two transmission lines failed during Blizzard Juno around high tide – furthering concerns that the nuclear plant is seriously unprepared to weather the storm.
PLYMOUTH — Depending on your perspective, Monday’s shut down of the Pilgrim Nuclear Power Station was either another example of the plant’s “defense in depth” safety or additional evidence of its vulnerability.
The press release from Pilgrim arrived just after 10 a.m. Tuesday morning, Oct. 15, and referenced a successful scram (sudden shutdown) of the reactor at 9:21 p.m. the previous evening. According to Pilgrim spokesman Carol Wightman, “Pilgrim Station automatically shut down due to the loss of one of the two 345-kV lines that provides offsite power to the plant.”
PLYMOUTH — A Monday night loss of outside power has forced the Pilgrim nuclear plant offline for the fourth time this year.
Carol Wightman, a spokeswoman for Pilgrim’s owner Entergy, said Tuesday morning that the plan automatically shut down at 9:21 p.m. Monday, when an NStar power line into the plant went out of service.
Wightman said Pilgrim gets its outside power from two 345-kilovolt lines. NStar had already taken one of the lines out of service for maintenance when the second line failed.
Wightman said the federal Nuclear Regulatory Commission was informed as soon as the shutdown occurred.
She said the shutdown had no effect on the health or safety to the public or Pilgrim workers. She said the 685-megawatt plant will return to production when NStar completes repair and restoration of the two power lines.
Wightman said emergency generators began operating as soon as the NStar line went out of service, and that the generators are safely powering the plant.
Meanwhile, she said Pilgrim crews are doing maintenance that can’t be performed while the plant is in production.
Pilgrim has now been offline for 73 of 288 days thus far this year, though 46 of those days were for planned maintenance and refueling.
The plant was offline three times earlier this year from pump-related problems. The plant was down for a week in January, and again in late August and early September.http://www.patriotledger.com/topstories/x1281960517/Pilgrim-nuclear-plant-offline-for-4th-time-this-year#ixzz2htkweZba
110 Pilgrim violations, 2000-2012
The Pilgrim nuclear power plant in Plymouth experienced 108 lower-level and two higher-level safety violations from 2000 through 2012. The violations were included in a congressional study expected to be released this month showing that safety violations at nuclear plants across the country varies dramatically from region to region. The Government Accountability Office report obtained by The Associated Press suggests inconsistent enforcement of regulations could be responsible.
A Pilgrim spokeswoman said they’re committed to addressing even minor issues and that enhancing safety is their top concern.
Twenty-six Northeast reactors reported more than 2,500 violations, about 97 per reactor, during the 13-year period. Lower-level violations pose very low risk. Higher-level violations range from low to high safety significance, such as an improperly maintained electrical system that caused a fire affecting a plant’s ability to shut down safely.
Shutdowns at Pilgrim in 2013
Jan. 10: Trip of both recirculation pumps. Returned to full power on Jan. 17.
Jan. 20: Leak in a safety-relief valve. Returned to full power on Jan. 24.
Feb. 8: Offsite power loss and main generator load reject. Returned to full power on Feb. 16.
April 18: Refueling. Returned to full power on June 3.
Aug. 22: Electrical problems with water pumps. The plant restarted on Aug. 26, but was shut down by a steam leak on Sept. 8 before reaching full power. Returned to full power on Sept. 21.
Oct. 14: Loss of offsite power.
Source: Nuclear Regulatory Commission
The Boston Globe: Ex-leader of Japan warns against nuclear power
IEEE Spectrum: Former NRC Chairman says Nuclear Industry is “Going Away”
Patriot Ledger: State senator calls for Pilgrim nuclear plant to be shut down
Cape Cod Online: Panelists outline problems with U.S. nuclear plant safety
Patriot Ledger: Panelists say Pilgrim nuclear plant should be closed
South Coast Today: Nuclear Experts: Retire reactors
Counter Punch: Toward a Clean Energy Future: The Nuclear Forum
WBAI Pacifica Radio: New York Lessons from Fukushima
Huffington Post: Nuclear Power Through the Fukushima Perspective
Business Week: Indian Point Nuclear Plant Should Be Shut, Ex-Regulator Says
Compiled by Dave Lochbaum, Union of Concerned Scientists – A 36-page printout of events that have occurred at Pilgrim, spanning from 1965 to May 2013.* Pilgrim Events (PDF)
*Important Note: This report contains information about events that happened – not events that did not happen. In other words, just because an event is NOT listed in this report does not mean it did not happen. It might be that the ongoing research effort that yielded this report has not yet recorded the event.
Table of Contents
Pilgrim: How Boiling Water Reactors Work 1
Spent Fuel Storage -Pool Fires 2
Containment Failure: Vent & Hydrogen Explosions 5
Pilgrim- Electric Reliability 10
Emergency Planning 12
Post Accident Cleanup 16
Risks From Daily Operations
Radiation Health Impacts 17
Marine Impacts 29
NRC Oversight- Public Participation- Alternatives
NRC Oversight 30
Public Participation 31
Do We Need Pilgrim’s Electric Power? 32
BWRs actually boil the water. In both types, water is converted to steam, and then recycled back into water by a part called the condenser, to be used again in the heat process.
Since radioactive materials can be dangerous, nuclear power plants have many safety systems to protect workers, the public, and the environment. These safety systems include shutting the reactor down quickly and stopping the fission process, systems to cool the reactor down and carry heat away from it, and barriers to contain the radioactivity and prevent it from escaping into the environment. Radioactive materials, if not used properly, can damage human cells or even cause cancer over long periods of time.