Update on Explosion at Hanford

[george.j.vargo@ccmail.pnl.gov (George J Vargo)]

ANNOUNCEMENT

Department of Energy                                        RL No.:  97-046 
Richland Operations Office
P.O. Box 550
Richland, Washington  99352                                 Issued:  5/19/97


To:  All Hanford Employees

Subject:  UPDATE ON PLUTONIUM FINISHING PLANT EVENT AT HANFORD 

EVENT RECAP:

A Hanford Site alert was declared following an explosion at Hanford's Plutonium 
Reclamation Facility, part of the Plutonium Finishing Plant complex, at 
approximately 8:00 p.m. PDT on Wednesday, May 14, 1995.  There was no known 
release of radioactivity and no Hanford employees were injured, though nine 
employees have been and continue to be evaluated for any illnesses.  The alert 
was terminated at 6:41 a.m. on Thursday, May 15.

INVESTIGATION CHRONOLOGY AND PRELIMINARY FACTS:

- Thursday morning I appointed the Accident Investigation Team and briefed Chair
Ron Gerton and Principal Investigator Rey Bocanegra, both of DOE-RL. The team 
began working that afternoon.

- Chair Ron Gerton has announced the following preliminary facts:

- The explosion occurred in Tank 109 in Room 40 of the Plutonium Reclamation 
Facility (PRF).  The room is outside of the plutonium processing areas and was 
used to mix non-radiological chemicals.

- At the time of the explosion the tank contained less than 40 gallons of a 
liquid solution of hydroxylamine nitrate and nitric acid.  The material was 
being retained for possible use in the deactivation of PFP.
- The mixture had a spontaneous reaction that generated large quantities of heat
and gas that overpressured the tank until the top blew off.  There was no fire.

- The reaction generated steam and oxides of nitrogen gas, which can be 
reddish/brownish/yellow in color.

- A contributing factor to the spontaneous reaction was evaporation of the 
solution leading to higher concentrations of the chemicals.

Gerton says that the team has a high degree of certainty that these preliminary 
facts are valid, but we will continue to work to confirm the details with 
independent experts and examine potential alternate scenarios.

In addition:

- DOE believes there are no other mixtures of this type at PFP, PUREX or B 
Plant.  It is also believed that the mixture does not exist anywhere at Hanford,
though all site contractors are actively checking their facilities at this time.

- These preliminary facts are being disseminated to the rest of the DOE complex.

- No exterior windows or doors were blown out during the explosion. However, 
further examination of the accident scene has revealed some structural damage:

-- Two small holes in the roof above Room 40 about 6" in size have been noted.  
There is no indication of any radiological release. Added operational controls 
were put in place after this discovery. DOE is in the process of investigating 
the rooftop by remote crane.  The design of the building is such that any air 
leakage at this time is into the building.

-- An interior, non load bearing, wall is bulged but not ruptured.

-- An Unreviewed Safety Question (USQ) has been declared to
resolve the explosion and structural questions.  A USQ is declared when a new 
situation is realized associated with a facility or activity that is not 
addressed in the safety documentation for that facility.

- Additional current information on current Recovery Team activities:

- No indication of airborne radioactive contamination has been found.

- Known air emission releases from the event are a short duration release of 
oxides of nitrogen gas and steam.

- The lab results on the water from the ruptured water line in the Plutonium 
Reclamation Facility which ran through the halls were negative on chemical 
contamination but a portion showed some radioactivity slightly above background 
levels.  This is believed to be due to the longtime presence of fixed 
contamination from a previous plant upset.  Following that upset, Room 40 had 
been cleaned up to the extent possible and the remaining contamination was fixed
in place.

- No water intrusion into the Plutonium Reclamation Facility canyon has been 
detected

- Cleanup and restoration of utilities allowed by the Accident Investigation 
Team is proceeding.

The Accident Investigation and Recovery Teams hit the ground running just hours 
after the accident.  They have made excellent progress supported by B&W Hanford,
the Plutonium Finishing Plant contractor.  In the early hours and days of such 
an event, it is normal that most people do not have all the known facts and 
there are gaps in "what happened" and "why."  We need to give the Accident 
Investigation Team the time they need to complete their investigation and report
that will give us the complete picture.  I will be keeping you updated as the 
work proceeds.

Lloyd L. Piper
Acting Manager