Nine Mile Point (USA)

Map of Nine Mile Point

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610 and 1100 MW BWR constructed by General Electric; grid connection in 1969 and 1987.

Facilities in Nine Mile Point

plantreactor typconstruction startoperation startshut down
Nine Mile Point-1BWR19651969
Nine Mile Point-2BWR19751987

Radwaste cask liner dropped at Nine Mile Point-1. Workers at Niagara Mohawk Power Corp's Nine Mile Point-1 dropped a radwaste cask liner after a drift pin on a lifting device sheared off. The liner was being loaded through an opening in he floor of the radwaste solidification and storage building to a truck below in the truck loading area. The liner was dropped about one foot above the floor opening on November 29 and became wedged in the opening. Workers got the liner free on December 1. The cask is now at the Barnwell, S.C. low level waste disposal site.


Unit started the planned outage 3 days early after operators determinded that several electric relays needed replacement. Outage is planned for 6-8 weeks; including partial replacement of turbine blades and inspection+repair of the core shroud.


THE REACTOR SCRAMMED DUE TO AN ELECTRONIC PRESSURE REGULATOR FAILURE. leakage in the RCS ( 2 lit/min REQUIRED A COMPLETE CORE OFF-LOAD. 2 manual valves in the ECCS condensate return and a check valve were replaced because of cracks caused by thermal cycling.


High neutron flux caused reactor pressure fluctuations -> failure of ERP in main turbine control (MPR did not respond, becuase of faulty calibrarion)primary coolant level fell about 0,7 m (but there was still 2,9 m water above the fuel, when SI started.) unit tripped, because operators were unable to stabilize reactor pressure.


On August 13, 1991, Nine Mile Point Unit 2 was operating at full power when
a fault occurred on phase B of the main transformer which caused the
generator, turbine, and reactor to trip. Station loads were transferred
automatically from the normal station service transformer, which receives
power from the generator, to the reserve station transformer, which receives
power from the grid. During the transient which lasted for about 12 cycles,
voltage on the station's phase B buses decreased to approximately 50 percent
of normal value before returning to normal.

The voltage transient resulted in loss of the power output from five of
eight nonsafety-related uninterruptible power supplies. Loss of these power
supplies caused the loss of control room annunciators, indication of control
rod positions, the core thermal limits computer, the process computer, the
safety parameter display system computer, the feedwater control system, some
instrumentation for balance-of-plant systems, some instrument recorders, the
plant radio and paging systems, and some of the lighting for the plant.
Some of the instrument recorders that were lost failed "as is." For
example, the average power range monitors continued to indicate 100% after
the reactor tripped. Nevertheless, control room operators were able to
verify from average power range meters and local power range lights mounted
on back panels and from other indications that the reactor actually had
tripped and was shut down.