Hanford (USA)

Map of Hanford

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WNP-2: 1100 MW BWR constructed by General Electric; grid connection in 1984.
(WPN 2 = Columbia)

Facilities in Hanford

plantreactor typconstruction startoperation startshut down
HanfordPu processing, weapons factory
Hanford WNP-2BWR19721984

Forest fires near Hanford nuclear complex reach radioactively contaminated territory, radioactivity is measured in the air.
(source: Greenpeace nuclear accident calendar)


Rupture of a fire protection system water main pipe , flooded part of the plant. The NRC staff attributed the pipe rupture to a design problem.
Smoke from welding activated the fire protection system and started all four fire pumps.
The force created by the four fire pumps, created a tremendous water hammer at the point where the water from the main pipe flows into the smaller sprinkler piping. The cast iron fire protection system valve that ruptured was sheared in half and roughly 480.000 liter of water gushed from the ruptured line.


The unit was down June 17 and maintenance work was being done when smoke from a welding job set off the sprinkler system. All four fire protection pumps started operating at the same time, which is not supposed to happen. That creatied a huge water hammer that ruptured a 300 mm fire protection line and valve.
Roughly 480 m³ of uncontaminated water gushed out of the broken line, flooding a nearby stairwell. NRC said pressure from the water eventually broke through the seal on a door to the room housing the unit's RHR pumps. The motor of one RHR pump was submerged.

NRC reported that when a valve in a line connecting the sumps of the submerged RHR pump and low-pressure core spray pump rooms failed to close, that water entered the low-pressure core spray pump room. The floodwaters did not reach the motors of those pumps.
The doors to the RHR and low-pressure spray pump rooms are supposed to have the required water-tight seals, but those seals are designed to keep the water in the rooms, not out.


An explosion at a plutonium recycling facility at Hanford last week tore the lid off a chemical tank and put the former DOE weapons plant in Washington state on a site alert that lasted nearly eight hours.
The pressure buildup in a 380 liter tank thought to contain hydroxylamine, an oxidizing agent, blew the bolted lid off, rupturing 100 mm water line in the process.
The building, which is being deactivated, has not been used for years. The explosion occurred, in a section of the plant where chemicals, used to remove plutonium residue from equipment, had been mixed. No one was in the room.
The head of the DOE team investigating the chemical tank explosion last week at Hanford has pointed to problems at the former weapons site that he says indicate "a total failure to recognize the hazard form day 1."
Ron Gerton said May 20 that a concentrated mixture of volatile chemicals is believed to have caused the May 14 explosion that ripped the lid off a 400-gallon tank at Hanford's plutonium recycling plant. However, DOE officials still do not know why the mixture was left there in the first place or why the tank was no longer monitored.
Even though plutonium operations at Hanford had been idle for years, a heavily diluted solution of hydroxylamine nitrate and nitric acid was put in the tank in 1993 for training purposes. Gerton said evaporation had reduced that750 liter mixture to roughly 100 liters, increasing the chemical concentration, by the time the blast occurred. Monitoring, which had been done on a monthly basis, was discontinued when the mixture dropped to 130 liters.


Officials at the Washington Public Power Supply System (WPPSS) hope to know by the end of December what caused an apparent increase in thermal power above the NRC-licensed limit at WNP-2.
The unit's full power operations have been reduced by 2.5% or between 25 and 30 megawatts electric, since routine tests in the fall showed a higher-than-normal feedwater flow.
Taylor said that most recently BPA temporarily kept WNP-2 around 60% power over the weekend. Aside from the cheap hydropower, the demand for electricity has dropped due to the unseasonably warm weather. Taylor added that WPPSS originally brought WNP-2 down to that level so it could do some on-line maintenance. The unit was at 63% power December 4.


As the unit was being brought up from an automatic trip the control room supervisor & the shift manager continued with the restart even though other operators in the control room alerted them that a water cleanup valve was partially open (should be closed).


Erroneous reading on water level monitor because of trapped non-condensable gases in reference leg piping after a scram. It was the first time a large, persistent level error occured. (Similar errors have been identified before at Millstone-1 and Pilgrim.)


Core wide power oscillations ocurred while returning to 100% power following drywell leakage investigation. The power level was swinging between 23% and 47% every 2 seconds for nearly a minute. AIT concluded that fundamental errors led to the oscillations: 1) fuel rod patterns and power distributions did not meet the BWR Owners Group guidance for avoiding instability. 2) plant engineers and the fuel vendor -Siemens Power Corp. - didn't adequately consider the potential for power instabilities in the fuel rod design. 3) a BWR Owners Group warning that operators should take special care when operating a unit between 25-35% was not incorporated into operating procedures. "those errors in the control of the nuclear fission process appeared to stem from a failure to perform technical work at an accepatble level of detail and quality", AIT. -- fuel was not damaged.


The main steam drain valves fo the MSIVs did not have an adequate electrical rating for an accident. Could result in the valves not closing after a steam line break outside of containment. Condition existed since initial operation.


Restart postponed twice after outage, because utility was unable to requalify enough operators to maintain 5 shifts.


Scram after explosion in the transformer yard, due to flashover.


Crack was found in the high pressure core spray: in a piping where a 20 mm line joins the 300 mm main piping.


Manual scram when a condensor tube failure triggered high impurity readings in the condensate. Debris from a ruptured bellows inside the condenser had damaged about 20 condenser tubes. The bellows drows steam from the plants low-pressure turbine.


During containment inerting and nitrogen supply tank refilling operations LN-2 passed through containment purge system piping and the purge system line ruptured where it connects the nitrogen line.