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The Three Mile Island (TMI) Nuclear Power Station Unit 1 is still operating and owner Exelon is pressuring Pennsylvania to approve subsidies to keep it open. The TMI replacement steam generators (by Areva-Le Creusot) apparently have a design defect, but may have material defects, as well. These could lead to another partial, or full, Three Mile Island nuclear meltdown. The design apparently causes steam generator tubes to flutter and strike or rub against each other. Material defects could make damage occur more quickly; lead to abrupt failures. Areva-Le Creusot sold a Reactor Vessel Closure Head (RVCH) to Three Mile Island, as well, which could be defective. Three Mile Island needs to be shut down. The world cannot bear another nuclear accident. Nor can Three Mile Island’s neighbors. (Three Mile Island unit 2 is the one which suffered a partial nuclear meltdown).

Report of The President’s Commission On the Accident at Three Mile Island (Kemeny et. al. Oct. 1979) , p. 32

The US NRC had concerns over Areva-Le Creusot testing and documentation at least as early as 2009. See more here: https://miningawareness.wordpress.com/2016/06/18/nuclear-reactors-at-risk-in-a-dozen-countries-due-to-anomalies-suspected-falsifications-at-arevas-creusot-forge-site/
Areva has mostly rebranded itself as Orano.

Excerpts from TMI Alert Petition for Enforcement Action to NRC:
an apparent design and manufacturing defect with the replacement steam generators at the Three Mile Island Unit 1 Nuclear Station (TMI) licensed to Exelon Generation Company LLC, the owner – Docket No. 50-289. The defects caused some of the steam tubes to become damaged by striking or rubbing against each other.

During normal operation, this does not appear to be a concern since the damaged steam tubes were taken out of service by plugging the ends. However, under reactor transient conditions, this defect could result in a thermally induced steam generator tubes rupture event. This in turn can result in a loss of coolant accident with core damage. “Steam generator (“SG”) tubes ruptures are potentially risk-significant events because thermally induced SG tube failures caused by hot gases from a damaged reactor core can result in a containment bypass event and a large release of fission products to the environment.”3″…

BACKGROUND
Steam Generator Tubes

“Steam generator (SG) tubes are small diameter, thin walled tubes that carry primary coolant through the primary to secondary heat exchangers. The SG tubes have a number of important safety functions. Steam generator tubes are an integral part of the reactor coolant pressure boundary (RCPB) and, as such, are relied on to maintain the primary system’s pressure and inventory. The SG tubes isolate the radioactive fission products in the primary coolant from the secondary system. In addition, as part of the RCPB, the SG tubes are unique in that they act as the heat transfer surface between the primary and secondary systems to remove heat from the primary system. This Specification addresses only the RCPB integrity function of the SG. The SG heat removal function is addressed by TS Section 3.4.

SG tube integrity means that the tubes are capable of performing their intended RCPB safety function consistent with the licensing basis, including applicable regulatory requirements.

Steam generator tubing is subject to a variety of degradation mechanisms. Steam generator tubes may experience tube degradation related to corrosion phenomena, such as wastage, pitting, intergranular attack, and stress corrosion cracking, along with other mechanically induced phenomena such as denting and wear. These degradation mechanisms can impair tube integrity if they are not managed effectively. The SG performance criteria are used to manage SG tube degradation.”

note: In the 1979 TMI partial meltdown, the steam generators initially failed to remove heat from the reactor.” (Excerpted from letter, below).

Three Mile Island Alert letter to the NRC with emphasis our own:









https://assets.documentcloud.org/documents/5767374/TMI-Alert-Petition-for-Enforcement-Action-Steam.pdf

In the US, nuclear reactors having potentially defective Le Creusot-Areva steam generators include: Prairie Island 1 and 2 (along with Reactor Pressure Vessels); Callaway; Arkansas One (along with reactor pressure vessel closure heads-lids); Salem; St. Lucie (along with RPV closure heads-lids, Pressurizers); Three Mile Island (along with RPV closure heads) (See Greenpeace France, Briefing ; AREVA – Société Générale / Investor day Burgundy – April 9, 2009)

Greenpeace briefing found here: https://miningawareness.wordpress.com/2016/06/18/nuclear-reactors-at-risk-in-a-dozen-countries-due-to-anomalies-suspected-falsifications-at-arevas-creusot-forge-site/
https://miningawareness.wordpress.com/2016/07/01/asn-possible-defects-in-areva-creusot-steam-generator-channel-heads-may-impact-countries-in-both-hemisperes-including-the-usa-us-nrc-snoozes/
July 17, 2012 NRC INFORMATION NOTICE 2012-07: TUBE-TO-TUBE CONTACT RESULTING IN WEAR IN ONCE-THROUGH STEAM GENERATORShttps://www.nrc.gov/docs/ML1207/ML120740578.pdf

Leaked letters show Hinkley-builder EDF warned over faulty nuclear parts