An update on the evaluation of personal air monitoring data at the savannah river site
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An Update on the Evaluation of Personal Air Monitoring Data at the Savannah River Site. T. R. La Bone D. J. Hadlock Westinghouse Savannah River Company Aiken, SC 29808. Outline . Some history on the use of PAS at SRS Why we developed a PAS program now The current PAS program at SRS

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An update on the evaluation of personal air monitoring data at the savannah river site

An Update on the Evaluation of Personal Air Monitoring Data at the Savannah River Site

T. R. La Bone

D. J. Hadlock

Westinghouse Savannah River Company

Aiken, SC 29808


Outline
Outline at the Savannah River Site

  • Some history on the use of PAS at SRS

    • Why we developed a PAS program now

  • The current PAS program at SRS

  • Evaluation of the Calendar Year 2003 data

    • Concurrent evaluation other aspects of the program

  • Dose Assignment from PAS

  • What happened After the Presentation


History of pas use at srs
History of PAS Use at SRS at the Savannah River Site

  • Prior to 2003 the use of PAS was not well received by RCO or Workers.

    • Results were calculated in DAC (Pu-239)

      • Used MDC for determining DAC-hr exposure

    • DAC-hrs for workers tracked manually (paper and pencil)

    • RCO only used PAS if someone held a gun to their head


History of pas use at srs1
History of PAS Use at SRS at the Savannah River Site

  • In 2002 we ran a pilot study in FB-Line for bioassay associated with highly insoluble Pu.

    • Included PAS

      • Still not well received, however there was light at the end of the tunnel.

        • Put a minimum PAS program into existence; some PAS equipment purchased.

    • PAS results were calculated only in DAC-hr

      • Volume of sample no longer an issue

      • Detectability based on counting equipment and PAS flow rate.


Calculating dac hr from pas
Calculating DAC-hr from PAS at the Savannah River Site


The light becomes brighter
The Light Becomes Brighter at the Savannah River Site

  • MDE is <2 DAC-hrs at 4 Lpm

    • Sufficient to determine if worker significantly exposed

    • Negates need to calculate DAC

  • Used Pilot program to do a few jobs

    • Middle of nowhere; no power; large area; etc.

    • Worked well

  • A few procedure revisions along with developing a DAC-hr tracking database maintained by the Central Counting Facility and we had a complete program.


Program outline
Program Outline at the Savannah River Site

  • Issue PAS to worker; up to six additional workers on one PAS.

  • In-Facility counting within 24-hrs to show <8 DAC-hrs, if not contact Internal Dosimetry.

  • Send to CCF and count after 120-hr decay.

    • CCF results placed in tracking database.

      • Flags any person >8 DAC-hrs single sample or,

      • Any person >40 DAC-hrs for CY.

      • Report generated for all workers >4 DAC-hrs for CY.


Use of pas by facility
Use of PAS by Facility at the Savannah River Site


Reason pas selected
Reason PAS Selected at the Savannah River Site


Srs pas rules of engagement
SRS PAS Rules of Engagement at the Savannah River Site

  • An exposure of >8 DAC-hrs in one day will trigger a special bioassay.

  • An exposure of >40 DAC-hrs in a CY will trigger a special bioassay.

  • The special bioassay will be used to assign dose unless the special bioassay cannot refute the exposure data.

  • In January, all cumulative exposures will be converted to dose using conservative DCFs.


Srs pas rules of engagement1
SRS PAS Rules of Engagement at the Savannah River Site

  • Doses between 10 and 100 mrem will be reported as calculated.

  • For doses >100 mrem, special bioassay samples will be requested and analyzed before the dose is assigned.


Analysis of 2003 results
Analysis of 2003 Results at the Savannah River Site





Bottom line
Bottom Line from U.

  • Reviewed all workers with >4 DAC-hrs cumulative exposure for CY 2003

    • Excluded the DAC-hr exposure for those events where a special bioassay was performed (3 workers).

    • Assigned dose based on conservative dose conversion factors

    • Sixteen workers assigned a dose ranging from about 11 to 45 mrem.

      • All assigned dose was from Uranium exposure (assumed Class Y)

  • End of 7/14/04 AMUG Session Talk.


Then what happened
Then What Happened? from U.

  • Phone Call the Next Morning

    • Non-HP Management was ‘concerned’ about the impact to the workers of being exposed internally and disagreed with our programmatic approach.

    • The assignment of dose to the workers for CY03 was put on hold.

  • Radiological Protection management concurred with our approach; DOE-SR Radiological Protection also concurred.

    • A few days of e-mails and face to face discussion.


So what s the problem
So, What’s the Problem? from U.

  • Conference call with Managers on August 24 of 04. List of concerns:

    • Summing PAS results (both + and -).

      • You must have an MDA; how can you see that small?

    • 4 DAC-hr Action Level (10 mrem)

      • To low; can’t see that low of a dose.

    • Why can’t we use in-vitro bioassay?

      • Our routine program must be deficient.

    • Why are we required to assign this dose?

      • We didn’t do this at Rocky Flats!


So what s the problem1
So, What’s the Problem? from U.

  • List of concerns (Cont.):

    • Why don’t we assign dose from a CAM?

      • You don’t use the “CAM in the corner”.

  • Other Concerns brought up in conversation:

    • If I had known workers were being exposed, I would have had RCO do something to stop it.

    • No one told our workers they would get internal dose assigned when wearing a PAS.

  • This started the long process of meetings with Senior Managers to come to a resolution.


Our responses to their concerns
Our Responses to Their Concerns from U.

  • Summing +/- PAS results

    • Explained the validity of this method

      • Wrote white paper detailing our justification

    • Showed that use of a DL did not affect the end results.

    • End result was that we decided it was not worth fighting for (end result not changed).

      • instituted calculating a DL for each PAS sample in the database.

      • Results <DL excluded from a worker’s total.


Our responses to their concerns1
Our Responses to Their Concerns from U.

  • Output from a worker’s annual exposure:


Our responses to their concerns2
Our Responses to Their Concerns from U.

  • 4 DAC-hr Action Level (10 mrem)

    • SRS uses a threshold of 10 mrem for reporting internal dose from a bioassay sample; applied to PAS to eliminate reporting insignificant doses.

    • Strict reading of the regulations would lead one to believe that any dose should be reported.

      • The real question, if you wanted to ask it, is why not less than 4?

    • Management decided they wanted doses reported quarterly.

      • Okay with us.


Our responses to their concerns3
Our Responses to Their Concerns from U.

  • Why can’t we use in-vitro bioassay?

    • Attempt made to say that if PAS could “see” the dose, then our bioassay program is deficient.

      • Continuing problem of management/workers believing that if their routine bioassay is negative, it means zero.

      • Discussions on what a routine bioassay can or cannot do for you.

        • Have been trying to get this point across for years. Too many energy units to absorb.

    • This concern was essentially dropped.

      • Beating up your bioassay program is not a good career path.


Our responses to their concerns4
Our Responses to Their Concerns from U.

  • Why are we required to assign this dose?

    • SRS is using PAS as a bioassay in some cases (e.g., Th-232, Pu-239SS). 10CFR835.702(b) states:

      The results of individual external and internal dose monitoring that is performed but not required by §835.402, shall be recorded.

    • What is your definition of recorded?

      • Write on an official document and file it away?

      • Record the dose and apply the results to the workers annual report card?


Our responses to their concerns5
Our Responses to Their Concerns from U.

  • If we are going to assign dose from a PAS, why don’t we assign dose from the CAM?

    • A CAM, unlike a PAS, is not always representative of the air the worker breathed.

    • If a CAM triggers a special bioassay, and the CAM is representative, the dose calculated from a CAM can be used if the bioassay cannot refute it.

      • Typically special bioassay can see less than the dose from the CAM and/or RCO is reluctant to call the CAM representative for the worker.


Our responses to their concerns6
Our Responses to Their Concerns from U.

  • If I had known people were being exposed, I would have had RCO do something about it.

    • Discussions on what is or is not a significant exposure.

      • If a person is in a NPFF respirator; air sample shows 100 DAC-hr; exposure is 2 DAC-hr.

      • Anything to be gained by going to a air-supplied hood?

        • Worn under the hood, exposure could be higher depending on how well the hood removal goes.

      • Zero exposure to radionuclides is not an achievable goal.


Our responses to their concerns7
Our Responses to Their Concerns from U.

  • No one told our workers they would get internal dose assigned when wearing PAS.

    • Hindsight: RCO should have explained this.

    • To reduce worker ‘discomfort’ decided that the 2003 PAS doses were just practice.

      • Real dose assignment will start in 2004

    • Developed a briefing sheet for RCO to use for worker briefing; became an Q&A to pass out.

      • Facility RCO does briefing.


The heart of the matter
The Heart of the Matter? from U.

  • In my opinion, there were two recurring points that drove the majority of management’s concern:

    • Internal dose is worse then external dose.

      • I realize that from a technical standpoint you are probably right but I still think it is worse. A rem is not a rem.

    • I don’t want to deal with workers angst about getting dose they never were assigned before; especially if it is internal.


Revised rules of engagement
Revised Rules of Engagement from U.

  • An exposure of >8 DAC-hrs in one day will trigger a special bioassay.

  • An exposure of >40 DAC-hrs in a CY will trigger a special bioassay.

  • The special bioassay will be used to assign dose unless the special bioassay cannot refute the exposure data.


Revised rules of engagement1
Revised Rules of Engagement from U.

  • At the end of each Calendar Quarter, all cumulative exposures based on counting results – not DAC-hrs, will be converted to dose using conservative DCFs.

    • PAS results <DL are excluded

    • Exposures >2.5 mrem are assigned

      • 2.5 mrem/qtr equates to 10 mrem/yr. Aligns with the SRS method for assigning tritium doses.



The end of the line
The End of the Line from U.

  • CY2004 doses from PAS were posted 2/24/05; 7 months to resolve.

    • 30 workers assigned doses ranging from 3 - 28 mrem for the year.

      • 21 workers had a dose assignment of 3 - 9 mrem.

    • Plan to post Q1 of CY2005 on April 15.

    • No feedback from Field on whether anyone has been upset by this information.

      • May depend on whether they are touched by the upcoming layoff.


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