Pilgrim Station is a General Electric Mark 1 Boiling Water Reactor. The prime contractor, Bechtel, began construction in October, 1967, and operation began in 1972, the same year that the Chairman of the Atomic Energy Commission acknowledged privately that this design could not contain a severe accident (see Hanauer Memo). Licensed for 40 years, it received a 20-year license extension on May 24, 2012 despite unanswered contentions before the NRC. Pilgrim has the same design as the three reactors that had meltdowns, exploded and breached their containments in Japan in March, 2011. Since only 33 such reactors have ever operated, based on real-world experience the odds of a severe accident at a Mark 1 are 1 in 11.
Mark 1 design:
Generic diagram of a boiling water reactor:
Fukushima Daiichi units 1, 2 & 3 suffered meltdowns, unit 4 (at left) had no fuel in the reactor but exploded anyway. Pilgrim has more than twice as much fuel in it’s radwaste pool as unit 4, where concerns of a spent fuel fire have caused Japan to consider evacuating Tokyo, about 140 miles away.