Critical Reflections about Doel3 & Tihange2

Integrity reactor vessels Doel 3 and Tihange 2

Page: 3

Contents:

p3: Construction of a nuclear reactor vessel. p4: Main points of criticism on the Electrabel safety cases p6: Identification of the flaws in the reactor vessel. p12: Hydrogen as cause of metal cracking. p17: Fracture mechanics. p18: Treatment of flaws by Electrabel. p20: Chronology of the events leading to the nuclear code case N-848. p23: Minor issues. p25: References. p28: Communication with FANC.

1 Construction of a nuclear reactor vessel.

Figure 1 presents the construction of a nuclear reactor vessel [ 21 ] . In the Electrabel–report [ 14 ] p17- 21, the construction of a nuclear reactor vessel is also described. The reactor consists of a cylindrical steel vessel with a diameter of 4 m, a wall thickness of 200 mm and a height of 13m. It is a PWR–reactor ("Pressurized Water Reactor"). The water in the reactor is pressurized by an external pressurizer at 155bar such that the water does not boil in the reactor. This primary water is heated by the nuclear core and circulated by pumps through the steam generators with a volume flow of 21190 m 3 / h in each loop, which produces the steam for the turbines which generate the electricity. The electrical power amounts 1020MW. The primary water enters the reac- tor vessel at a temperature of 282 o C, flows between the core barrel and the vessel wall downwards and subsequently back upwards through the core and leaves the reactor vessel at a temperature of 325 o C. The reactor vessel is designed to withstand a pressure of 171 bar and is tested at a pressure of 215 bar. Figure 2 (figure 3.5 in the report [ 14 ] p20) presents the construction of the reactor vessel of Doel 3.

The vessel has been welded together from different forged parts. The reactor has started up in 1982 and is about 34 years in use.

R.Boonen & J.Peirs

May 18, 2017