# Presentation: 195332

## Joanne D. LorenceProgram Engineer,Facility RepresentativeNNSA Los Alamos Site Office

- Lessons Learned from
- Type B Accident Investigation of the August 5, 2003 Plutonium-238 Multiple Uptake Event at the Plutonium Facility,Los Alamos National Laboratory, New Mexico
- Douglas M. Minnema, Ph.D., CHP
- Type B Investigation Board Chairperson
- NNSA Service Center

**Notes:**
Purpose of investigating our accidents is to learn from them, but to avoid recurrence we must do more than write down the lessons learned, we must internalize and apply them in every operation at all our facilities.

## Background

**Plutonium-238 operations**
**2 Occurrence Reports in October and November 1994**
**Contractor-performed Type C Accident Investigation, Glove Box Fire and Decomposition of Rags, November 1994**
**Defense Nuclear Facilities Safety Board (DNFSB) Recommendation 1994-1 and 2000-1**
**DOE Type A Accident Investigation, Plutonium-238 Multiple Intake Event, March 2000**
**Federal oversight**

**Notes:**
This accident could have been prevented.  Ops in 1994.  The Pu-238 oxide  heat source fabrication produces fine particles easily dispersed from surfaces as aerosol.
Pu taken into lungs by inhalation will slowly be dissolved, but will be captured & retained by your liver and bone surfaces for an indefinite amount of time, thus a small intake can result in a significant internal radiation dose.
2 ORPS Oct/Nov 1994 within the 200 wing (same activity investigated): Thermal Decomposition of Rags and Burning Rags in GB.
As a result, 1994, Type C some of the Findings and JONs were: 
No approved disposition plan for Pu-238 contaminated cheesecloth.  No WM Plan. Cans accumulated.
Storage of waste cans containing Pu-238 contaminated cheesecloth in room 201B poses an unevaluated hazard.
Inspect or analyze need to use cheesecloth - combustible.
Limit quantity of Pu-238 in each can.
Process backlog of cans in room 201B on a reasonable yet expedited schedule.
In 1998, DOE IP 94-1 commits to complete stabilization of LANL excess Pu inventory by FY2005.  In 2001, DOE IP 2000-1 extends LANL stabilization schedule to FY2010, Rev2 adds programmatic (non-excess) items to FY2010 schedule.  In addition, the Board cites risks of maintaining legacy residues in sliplid cans.
March 2000 DOE Type A identified again within the 200 wing at the Pu facility:
“Weaknesses in work planning and control, formality of ops, and hazard analysis significantly weakend the barriers between the workers and the hazard.
LANL missed opportunities to adequately analyze and learn from previous events.
Lack of balance between control of ops, reliance on workers’ knowledge, communications between work groups, and barriers designed to prevent adverse events.”

## The Accident - Room 201B

**Room 201B is a 29’ by 14’ room adjacent to a NMT-9 processing area. The room is used mainly for storing packages containing Pu-238 residues and contaminated materials generated by NMT-9 processing activities. **

**Notes:**
 Aug 5, 2003, at approx 210pm, CAM alarmed.
Room 201B at the time of accident had approx 200 cans in storage.
Detectable levels of external contamination on clothing, hair, and skin.
 Initial dose estimates (based on nasal swipes) suggested 10 rem Committed Effective Dose Equivalent (CEDE) which is twice the DOE annual limit for occupationally exposed workers.
Estimated dose at time of the AI was 2rem and 3rem CEDE.
Latest values today are 7.5 rem and 10 rem CEDE.
High Radiation Area behind shield wall.

## The Direct Cause

**Release of airborne contamination from a degraded package that contained cellulose material and Pu-238 residues. The failed package had been in storage since 1996.**
**Radiolytic, chemical, and thermal decomposition of the contents and the packaging materials caused the failure of two inner boundaries.  Corrosion sealed the “breathable” seams of the outer boundary, allowing decomposition gases to build up inside package.**
**Simple handling of package dislodged corrosion at seam junction, allowing venting of contaminated gases to room****.**

**Notes:**
For release to occur, 3 basic conditions were present:
First – Source material.
Second – Failure of all boundaries – Can Bag Can
Third – Motive force.
Hot spot = 600,000 dpm/100cm^2 (total alpha)
Suspect can was categorized into LANL inventory records as “Combustibles” containing 20.5 g Pu-238.

## Inner Boundary Failure

**The inner boundary was a slip-lid can of same design as outer can, but had a particulate filter mounted on the lid. Contents were Pu-238 contaminated cheesecloth. May have had residual nitric acid, cleaning solution, and water.**
- Thermal and radiolytic decomposition of cheesecloth creates water and gases.
- Bottom of can corrodes to failure and separation from sidewall.
- Sidewall corrodes to failure near bottom of can.
- (Note: photos are views of the bottom of the can)

**Notes:**
Starting from the inside and working out:
Pu-238 heat and radiolysis deteriorates cheesecloth.
Gases are generated.
Note:  looking at bottom of can.
Note:  During the investigation, the material handler needed to stop every 15-20 minutes because he said the can was “very warm.”
Note:  These cans were procured without specifications, testing requirements, or standards.

## Bag Failure

**The second boundary was a heavy gauge PVC bag with a particulate filter. This “bag-out” bag is used to contain the contaminated inner can when it is removed from the glovebox.**
**Exposure to alpha radiation caused decomposition of the PVC bag, resulting in generation of hydrogen chloride, which combines with water vapor to create hydrochloric acid. This is indicated by browning of the bag.**
**Hydrochloric acid contributed to corrosion of the inner and outer cans.**
**Weakened bag fails at stress point along seam on bottom of bag.**

**Notes:**
The 2nd boundary to fail was the bag.
Pu-238 radiolysis deteriorates bag.

## Outer Boundary Failure

**The outer boundary was a slip-lid “foodpack” can with the lid circumferentially taped with vinyl tape.  No particulate filter was installed on this boundary,  seams and lid were assumed to “breathe” as per manufacturer.**
- Acid and water vapor, and decomposition gases passed through filters on inner boundaries and attacked outer can.
- Corrosion products collected under the lid, and held in place by the tape, inhibited breathing around the lid.
- Corrosion products collecting around the bottom edge of the can sealed the seam.
- (**Note**: No significant defects are visible on the exterior of the can.)

**Notes:**
The third boundary to fail is the outer can.
Moisture, corrosive vapors and heat deteriorate the inside of the can.
Rust forms on outer seams and inhibits breathing causing can to overpressurize.

## Board Conclusions

**This accident was preventable.**
**The Board concluded that observed failure mechanisms were similar to those previously observed within LANL and DOE. Reference documents include:**
*Summary of Plutonium Working Group Report on ESH Vulnerabilities associated with the Department’s Plutonium Storage*, DOE/EH-0415, 1994;
_**Plutonium Storage Safety at Major Department of Energy Facilities, DNSFB Tech Report #1, 1994;**_
*Criteria for Safe Storage of Plutonium Metals and Oxides*, DOE-STD-3013, first published in 1994;
_**Plutonium Dioxide Storage: Conditions for Preparation and Handling, LA-12999-MS, 1995;**_** and**
*Criteria for the Interim Safe Storage of Plutonium-Bearing Solid Materials*, DOE, 1995.

**Notes:**
Dozens of conclusions were determined by the Board, let me highlight (in blue) a few that are applicable as an FR:
This accident was preventable. 
Become familiar with Defense Board issues that apply to your facility operations.
Recommendation 94-1/00-1 were borne from a 1994 DNFSB Tech Report discussing such areas as:
Alpha radiation from Pu would irradiate and decompose bags.
Corrosion converts Pu to a highly dispersable form.
Container should be DOE-approved stainless steel.
Implement inspection/surveillance rqts.
Pressurization of can is a hazard
Suspect materials include combustibles such as nitrated cellulose materials (cheesecloth for wipedowns).
In addition, LANL NMT participated in and published studies as early as 1994 to understand storage phenomena of Pu.

## Board Conclusions (cont)

**The Board concluded that:**
**The **_**technical basis**_** for the Pu-238 residue packaging and storage activities was inadequate, ineffective, and in some cases nonexistent;**
_**Lessons learned from previous events**_**,**** including events occurring within the same activity, had not been effectively incorporated into practices;**
**The release could have been significantly higher, but for fortuitous geometry and timing, and there were no barriers in place;**
**There was **_**no Hazard Control Plan**_** in place for the activities in room 201B, and the established work controls were inadequate and ineffective;**

**Notes:**
Know the technical basis for operations.  
The SAR identified:  The only established control were the seismic constraints for the cages.  However, this requirement was not proceduralized to be performed formally.
Become familiar with previous accidents, reportable events, DNFSB reviews that occur at your facility.  There was a Type C AI in 1994 that was never formally closed by the contractor.  As mentioned earlier, the Type C investigation determined: 
No WM Plan for room 201B – cans accumulated without WM Plan.
Storage of waste cans containing Pu-238 contaminated cheesecloth in room 201B poses an unevaluated hazard.
Inspect or analyze need to use cheesecloth - combustible.
Limit quantity of Pu-238 in each can.
Process backlog of cans in room 201B on a reasonable yet expedited schedule.
Recall, the DOE Type A determined in March 2000: 
LANL missed opportunities to adequately analyze and learn from previous events.
Lack of balance between control of ops, reliance on workers’ knowledge, communications between work groups, and barriers designed to prevent adverse events.”
Become familiar with the Hazard Control Plans for activities in your facility.  
No analysis of interaction between contents and packaging materials.
No controls on the quantity or type of materials that could be placed into a package.
No formal inspection/surveillance program to determine package integrity.

## Board Conclusions (cont)

**The Board concluded that:**
**Some procedures existed that may have reduced the probability of this accident, but adherence to procedures was not enforced;**
**The packages were placed in storage with **_**no schedule for disposition;**_
**NMT implementation of ISM inadequate and ineffective; and**
_**NMT, LANL, and DOE Oversight inadequate and ineffective.**_

**Notes:**
Many groups were responsible for providing oversight of this activity:
The contractor organization.
DOE NE-50, Space Reactor Program for program and budget guidance.
NNSA Materials mgt, Waste mgt, Facility ops.
However, there was no integration to manage this activity from cradle-to-grave.

## Complacent Safety Culture

**The Board is very concerned about a weak safety culture that was complacent towards procedures and accepted risks without understanding consequences.**
_**Operational practices were often inconsistent**_** with applicable procedures, instructions, and site-specific training (e.g., CAM alarm response, glovebox cleaning, Ops. Center logs);**
**Confusion often existed regarding the applicability of various requirements to actual operations (e.g., SNM packaging, radiation protection, ALARA);**
_**Confusion existed over intention of RWPs**_** and what the requirements actually were (e.g., “continuous coverage,” “taped openings,” number of gloves, sign-in and pre-job briefs);**

**Notes:**
Finally the last conclusion that was identified was a weak safety culture.
There continues to be a heavy reliance on knowledge and experience of individual workers/scientists without strict adherence to procedures.

There was heavy reliance on the RWP as the only “procedure” for all activities within 201B. 

## Weak Safety Culture

_**Involvement of subject matter experts**_** in operational decisions was marginal (NMT-2, NMT-4, NMT-7, NMT-11, NMT-14, and NMT-16 all have SMEs that could have assisted);**
**Worker safety expectations were often informal and not clearly understood by staff (e.g., “two-man-rule for safety,” 50 mrem/day ALARA goal);**
**NMT **_**policies/expectations were inconsistently applied**_** to Pu-238 and Pu-239 operations (e.g., cheesecloth & nitric acid, Vault controls vs. room 201B controls);**
**SAR assumptions about worker safety were not carried forward to practices.**

**Notes:**
Division subject matter experts were stove-piped and there was no exchange of lessons learned between the organization.  Although LANL NMT scientists published several studies on Pu storage.
NMT-4, Nuclear Materials Mgt
NMT-7, WM
NMT-11, Actinide and Fuel Cycle
Within the same facility there were 2 different Pu operations operating to different criteria – in packaging, use of cheesecloth, residue and waste mgt and it was determined that the Pu-238 line with the most hazardous radionuclide had the least stringent controls.

## Root Causes

**RC1 - The NMT failed to balance management attention and resources between accomplishing the programmatic mission and providing an appropriate level of protection for the workers handling Pu-238.**
**RC2 - The DOE, NNSA, and LANL failed to adequately evaluate and understand the magnitude of the worker safety risks that they have accepted for the activities conducted by the NMT-9.**
**RC3 - The DOE, NNSA, and LANL managed the DNFSB Recommendations 1994-1 and 2000-1 as projects for addressing legacy materials storage rather than as an effort to mitigate potential hazards to workers.**

**Notes:**
Program vs. safety

Acceptance of risk without attempting to understand the magnitude of the consequences or probability of occurrence.

94-1/00-1 managed as a project.  Corrections to “baseline” were made as funding became available.  There was no change in disposition of unsafe packages as a worker safety issue.

## Lessons Learned

**There are two important lessons to learn from this investigation:**
**This accident could have been avoided through the proactive evaluation and incorporation of lessons learned from both internal and Department-wide experiences. There was enough information available before this activity began, and more became available during the storage of these materials, to provide an understanding of the issues involved.**
**This accident could also have been avoided if the safety culture was one which always questioned the adequacy of current practices; one that pondered the possibility of failure rather than assuming success; one that understood that risks should only be accepted after evaluation and thoughtful consideration; and one that always pursued improvement.**

## FR Value Added

**There are important lessons to learn from this investigation as an FR:**
**Review previous Accident Investigations, ORPS, DNFSB reviews prior to FR assignment to facility.**
**Verify flowdown of safety basis requirements, especially the less obvious requirements that do not have specific TSRs.**
**Do not accept status quo. **
**Adequate FR coverage is necessary to ensure appropriate **_**depth**_** of oversight.**
**Ensure knowledge and communication of facility operations status provided to program sponsors.**
**Very good opportunity for FR to enhance their technical competency and proficiency as AI board member.**