# Presentation: 937733

## Quantitative Evaluation of Contamination Consequences (QECC) Project Experiences Using ORPS

- Presented January 27, 1999 at the
- Office of Operating Experience Analysis and Feedback (EH-33)
**Data Analysis Forum**
- Las Vegas, Nevada

- Charles R. Watson, Daniel J. Strom, Paul S. Stansbury
- Risk Analysis & Health Protection,
-  Pacific Northwest National Laboratory
- Richland, Washington
- Work supported by the U.S. Department of Energy Office of Environment, Safety and Health (ES&H) Office of Worker Protection Programs and Hazards Management under Contract No. DE-AC06-76RLO 1830

## Goals

- Quantify available information that relates surface and volume contamination of equipment and materials to intakes, doses, and health risks to workers
- Quantify how well air sampling predicts worker intakes and what factors improve or degrade the usefulness of air sampling to manage worker risks

## QECC Approach

- Objective: *quantitative *lessons learned
- radiological
- chemical
- Emphasize human health consequences
- Assemble, organize, analyze historical data
- Tap previous research (journals, reports)
- Compute “Outcome Measures” that can be used for setting contamination standards
- Future: collect info that’s out there already

## Sources of Data

- IAEA reports
- NRC Information Notices
- NRC NUREGs
- DOE Occurrence Reporting and Processing System (ORPS)
- Peer-reviewed literature
- Nuclear Power industry (?)

## QECC must account for a multitude of pathways. It must also deal with need to infer many intermediate values.

**Notes:**
For decades, the phrase "time, distance, and shielding" has been presented as summarizing the "basics" of radiation protection. 
Indeed, for protection from external radiation sources, these three principles are probably the most important ones on which a worker can make decisions and take actions.  

However, these principles do not address protection against intakes of radioactive materials or "ontakes" (skin contamination), other risk-limiting measures, or other important protective measures taken by governments, public health agencies, regulators, and institutional programs.
Performance standards, health education, facility engineering requirements, and administrative procedures.

Furthermore, "time, distance, and shielding" simply do not apply to many radiation protection situations, such as indoor radon.  And finally, the standard liturgy of "time, distance, and shielding" doesn't tell the worker what action to take.  For these reasons, I have chosen to separate the principles (short names) from the commandments (what to do).

## General Case

- Resuspension

***Amount of Activity***
- in Process

- Event releases
***Airborne Contamination***

***Surface ***
***Contam.***

***Skin ***
***Contam.***

***PPE***
***Contam.***

- Contamination
- absorbed
- through skin

- Contamination
- ingested

- Contamination
- inhaled

***BZ air***
***sample***

***GA air***
***sample***

- Bioassay

***Nasal***
***Smear***

***Intake Inferred***
***from Bioassay***

***Assessed***
***Dose***

- Deposition

***Respiratory***
***Protection***

***Person’s***
***Exposure***
***Time***

***Intake Inferred***
***from Air Sample***

## Numeric Data is Essential

- type and amount of material in process
- the nature, extent and amounts of removable and total surface contamination, airborne contamination (when available)
- description of work or incident and amount of time workers were present
- location description: volume, surface area
- for each individual involved:

- bioassay results
- nasal smear results
- doses
- medical outcomes (if any)

- personal protective equipment
- respiratory protection
- intakes
- ontakes (skin contamination)

## QECC Outcome Measures 1

- intake rate from surface contamination (hr-1)
- resuspension factor (m-1)
- observed breathing rate (m3/hr)
- intake rate from skin contamination (hr-1)
- fraction-taken-in (dimensionless (or "per situation"))
- fraction-taken-on (dimensionless)

## QECC Outcome Measures 2

- time-and-proximity factor (unshielded) (hr/m2, i.e., “hours at a meter”)
- representativeness of air samples (dimensionless) :
- GA intake / BZ intake
- BZ intake / bioassay intake
- GA intake / bioassay intake

## QECC Outcome Measures 3

- intake per unit nasal deposition (dimensionless)
- observed respiratory protection factor where Assigned Protection Factor *(APF)* =
- 1 (no mask)
- 10 (“partial” or half mask)
- 50 (full face)
- 1000 (fresh air)

## Example:Intake Rate from Surface Contamination

- QECC staff will do unit conversions
- values needed:
*A* 	intake (activity in Bq) by person
*B* 	activity (Bq/m2) on contaminated surface
*C *	area of contaminated surface (m2)
*D* 	time person was in contact with contamination (h)
*E* 	protection factor of respirator (if missing, use 1.0)
*I*surf (per hour) = *A**** E  /  (B**** C**** D)*

## Preliminary Results:Intake Rate from Surface Contamination

- Number			 	48
- Mean				1.9E-6 h-1
- Standard Deviation (SD)	1.0E-5 h-1
- minimum			1.6E-11 h-1
- maximum 			7.0E-5 h-1
- Geometric mean 		3.9E-9 h-1
- Geometric SD 		83

## Difficulties with Reported Data

- completeness is a real problem
- the people involved in the event knew everything we need to know, but rarely report it
- reporting as “less than” or “undetectable”
- known as “censoring” data
- without decision level (*DL* = *L**C*)
- many reports confuse *DL* with minimum detectable amount (*MDA* = *L**D*)
*MDA*, *DL*, and uncertainty for each measurement method are seldom reported but are certainly available

## Initial Experience with ORPS

- Downloaded 790 reports for evaluation
- Hanford, Los Alamos, and a few other sites
- “nasal smear” as indicator of contamination
- Convert from text file to database records
- WordPerfect 8 macro, Access import function
- Methodology and software available on request
- Individually reviewed for applicability
- (we could not automate evaluation)
- Many resulted in QECC records

## QECC’s Current Use of ORPS

- Monitor daily, using word processor search for: “nasal smear,” “bioassay,” or “contamination”
- Identify occurrences that will yield outcome measures
- Contact authors, request completion of  supplementary information forms, follow up via telephone

## Some Interesting Current ORs

## 12/9/98 Unplanned Tritium Emission from the Radiochemical Processing Lab 

- source term well characterized
- 90 Ci released
- several hundred Ci still in process
- QECC needs
- results of special bioassay that was scheduled for all staff in room (results are expected to be negative)
- indication of how many people were involved

## 12/14/98 Committed Effective Dose Equivalent Limit Exceeded in SW19 

- “The initial sample result was slightly above the Decision Level (less than *MDA*) and the re-analysis confirmed the positive result (> *DL* but less than *MDA*).”
- QECC needs *numerical values* for
*DL*
*MDA*

## 12/29/98 Clothing Contamination at Plant 8 NW Pad 

- worker fell through grating and stepped in sludge trench
- QECC needs
- quantity of material in trench
- bioassay results

## 1/6/99 Personnel Exposure Exceeding 100 mrem Total Effective Dose Equivalent

- what kind of Pu
- what the DAC was (Ci/cm3, Bq/m3, etc.)
- how long the worker was in there
- what the bioassay *DL* and *MDA* were for special bioassays
- nasal smear results
- respirators, anti-C's, gloves, booties, shoe covers, tape, etc.
- who else was exposed and all of the above for each, including any who had special bioassay

## 1/11/99 Shoe Contamination Found Upon Buffer Area Exit Frisk 

- Example of OR system working well
- Contamination of unexpected type prompted examination of workplace for source
- Follow-up with author

## Conclusions (1)

- QECC Database is powerful analytical tool
- Data we need are already out there, but rarely recorded
- Data need to be complete for *quantitative *lessons to be learned

## Conclusions (2)

- Radioactive Contamination: Need quantitative answers
- ORs  provide incomplete glimpse at contemporary experience
- QECC team may be asking you for supplementary information about selected occurrences in 1999

## Questions or Comments?

- Chuck Watson, PNNL
- (509) 376-3483
- chuck.watson@pnl.gov
- Dan Strom, PNNL
- (509) 375-2626
- daniel.j.strom@pnl.gov
- Paul Stansbury, PNNL
- (509) 375-6937
- paul.stansbury@pnl.gov

**http://QECC.pnl.gov**
- Joel Rabovsky, DOE, EH-52
- (301) 903-2135
- joel.rabovsky@eh.doe.gov