# Presentation: 611644

## Dose Rate Characterization in Cladding Samples; How to Minimize Extremity Exposures- An ALARA Challenge

***Marcia Maria Campos Torres***
***Mary Jo Ridenour***
*Radiological  Safety Organization*
*Environment Safety and Health Division*
*DOE Radiological Protection Workshop*
*November 27-29,2007*

## Objective

**Perform Cuts on Extremely “Hot” Samples Inside a Glove Box**
**Maintain Exposures To the Extremities As Low As Possible**

## Background

**New Cladding Samples Arrived on Site in 2005-2007 with Reactor Discharge Dates of 2001-2004.**
**Defueling Performed at Other Labs**
**Potential Exposure Rates at Contact Up to 300R/h ******
**Beta is the Main Component**

## Background

**Previous Work Performed In Cladding Samples  Discharged from the Reactor in 1995 After Significant Decay of Fission Products(e.g.;Cs-134)**
**On Contact Gamma and Beta-Gamma Dose Rates Were Relatively Low**

## Background

**Origin Code Calculations Show that New Samples Contain Fission Products That Will Deliver Significant Dose Rates Beta-Gamma and Gamma at Contact**
**Main Radionuclides are: Cs-134,Cs-137,Sr-90,Sb-125,Eu-154, etc**
**The Challenge How To Allow Work To Be Performed and Keep Exposures ALARA?**

## Dose Characterization

**Try to Understand the Exposures Coming out of the Samples-Energy Range**
**Perform a Dry Run with Scientist to Find Out How the Work is Going to be Done, How Long it Takes to Cut a Sample?**
**Based on the Dry Run Results Estimate the Whole Body Exposure and Extremity**
**Parameters Were Set; Measurements Were going to be Performed at 8cm (length of workers finger) and 30cm from Source**

## Dose Rate Characterization of High-Burnup M5 Cladding Sample (645B) in IML Cell #4

## Dose Rate Characterization of High-Burnup M5 Cladding Sample (645B) in IML Cell #4

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## Glovebox #9, DL-114 Radiological Laboratory

- a

## Dose Rate Characterization of High-Burnup ZIRLO Cladding Sample (648H) in IML Cell #4

|  | Step Description | RO7 Detector |  |  | TLD |  |
| --- | --- | --- | --- | --- | --- | --- |
|  |  | on contact, R/h | 8 cm from the sample, R/h | 30 cm from the sample, R/h | 8 cm from the sample, R/h | 30 cm from the sample, R/h |
| 1 | Unshielded sample
Position A,R/hr β+γ | 97 | 6 | 0.7 |  14.4 (shallow dose) | 0 (shallow dose) |
| 2 | Unshielded sample
Position A, R/hr γ | 11 | 0.6 | 0.2 | 2.0 (deep dose) | 0 (deep dose) |
| 3 | Unshielded sample
Position Bc,  R/hr β+γ | >200a/>200b | 17 | 1.0 | – | – |
| 4 | Unshielded sample
Position B, R/hr γ | 5.5 | 0.5 | 0.1 | – | – |

## Dose Rate Characterization of High-Burnup M5 Cladding Sample (645B) in IML Cell #4

|  | Step Description | RO7 Detector
R/h |  |  | TLD, deep dose
Gamma |  | TLD, 
Beta-Gamma |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  |  | on contact, BG | 8 cm from the sample, BG/G | 30 cm from the sample, BG/G | 8 cm from the sample, R/h | 30 cm from the sample, R/h | 8 cm from the sample, R/h | 30 cm from the sample, R/h |
| 1 | Through pipe nipple | 12 | – | – | – | – | – | – |
| 2 | Unshielded sample | 310 | 14/1.3 | 2.3/0.2 | 11.3 | 0.7 | 58.7 | 0.7 |
| 3 | 0.08 mm Al -shielding | – | – | – | – | – | – | – |
| 4 | 1.03mm Al -shielding | 90 | – | 1.4 | 4.9 | 0 | 48.5 | 0 |
| 5 | 2.02 mm Al -shielding | 25 | – | 0.8 | – | – | – | – |
| 6 | 12.4 mm acrylic shielding | 12 | – | 0.4 | 1.4 | 0 | 8.9 | 0 |
| 7 | 6.5 mm plastic shielding | 20 | – | 0.6 | – | – | – | – |
| 8 | 3 mm glass shielding | 20 | – | 0.3 | 1.5 | 0 | 4.3 | 0 |
| 9 | 10 mm paper shielding | 15 | – | 0.3 | 1.7 | 0 | 6.9 | 0 |

## Best Glove Pb X W  Lined?

| Material | Sample# | Ring# | DosimeterID # | Gamma Dose
mrem/min | R/hr Readings |  |  |  | Surface |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  |  |  |  |  | B/G @ 8cm | B/G @ 30cm | G @ 8cm | G @ 30cm |  |
| W | 645D | Ring 1 | 2605 | 61 | 21.0 | 1.8 | 1.8 | 0.2 | ruler on table |
|   |   | Tube 1 | 0001 | 1726 | 19.0 | 1.6 | 1.2 | 0.2 | plexiglass on table |
| Pb 0.6 | 645D | Ring 4 | 1060 | 71 |   |   |   |   | with RO-7 |
|   |   | Tube 4 | 0004 | 1046 |   |   |   |   |   |
| Pb 0.8 | 645D | Ring 7 | 0068 | 52 |   |   |   |   |   |
|   |   | Tube 7 | 0007 | 717 |   |   |   |   |   |
| W | 645A | Ring 2 | 1346 | 62 | 19.0 | 1.3 | 1.4 | 0.2 | ruler on table |
|   |   | Tube 2 | 0002 | 2072 | 20.0 | 1.7 | 1.4 | 0.2 | plexiglass on table |
| Pb 0.6 | 645A | Ring 5 | 1646 | 56 |   |   |   |   | with RO-7 |
|   |   | Tube 5 | 0005 | 211 |   |   |   |   |   |
| Pb 0.8 | 645A | Ring 8 | 1687 | 66 |   |   |   |   |   |
|   |   | Tube 8 | 0008 | 1660 |   |   |   |   |   |
| W | 645C | Ring 3 | 2136 | 41 | 23.0 | 1.8 | 1.9 | 0.2 | ruler on table |
|   |   | Tube 3 | 0003 | 796 | 18.5 | 1.7 | 1.5 | 0.2 | plexiglass on table |
| Pb 0.6 | 645C | Ring 6 | 2574 | 66 |   |   |   |   | with RO-7 |
|   |   | Tube 6 | 0006 | 985 |   |   |   |   |   |
| Pb 0.8 | 645C | Ring 9 | 1364 | 122 |   |   |   |   |   |
|   |   | Tube 9 | 0009 | 969 |   |   |   |   |   |

## Best Glove PB X  W Lined?

**Results  Are Not Conclusive that PB Lined Gloves Are Always a Better Shielding**
**For Sample 645C it seems that W Lined Gloves Were a Better Shielding**
**For Samples 645A/D Pb Lined (0.6 or 0.8mm) seem to Be  Equal Equivalent**

## Analytical Chemistry  Sample 645A

**1 mm Ring of the Above Sample Was Submitted to the Analytical Lab in Order to Verify the Main Radionuclides**
**A Gamma Spectroscopy Analysis and a Chemistry Dissolution was Performed on the Sample**
**Results Show......**

## Gamma Spectroscopy-Cladding Sample  645 A2, 645A2

| Submitter’s Sample No. |   | 645A6 |   | 645A2 |   |
| --- | --- | --- | --- | --- | --- |
| ACL Sample No. |   | 01 | 02 | 02 | 04 |
|   |   |   |   |   |   |
| Radionuclide |   | uCi/g |  | uCi/g |  |
|   |   |   |   |   |   |
|   | Ag-110M | 0.15 | 0.005 | 0.16 | 0.005 |
|   | Ce-144 | 6.51 | 0.20 | 6.53 | 0.20 |
|   | Co-60 | 0.61 | 0.018 | 0.61 | 0.018 |
|   | Cs-134 | 28.52 | 0.86 | 28.43 | 0.85 |
|   | Cs-137 | 52.41 | 1.57 | 52.17 | 1.57 |
|   | Eu-154 | 2.87E+00 | 0.086 | 2.85 | 0.086 |
|   | Eu-155 | 0.91 | 0.027 | 0.94 | 0.028 |
|   | Mn-54 | 0.030 | 0.001 | 0.027 | 0.001 |
|   | Sb-125 | 2.46 | 0.074 | 2.86 | 0.086 |
|   | Zn-65 | 3.42E-02 | 0.001 |   |   |

## What Have We Learned So Far?

- Samples Freshly Removed from Reactors are Difficult to Work on
- Instruments Might Have To Be Recalibrated to Address the Main Beta Components
- Initial Conservative Extremity ALARA Goal Was Set at 100 mrem per Sample
- Updated ALARA Goals for Extremity up to 250mrem per Sample Was Required After Further Characterization
- Collective Extremity Exposure Per Year Was Set at 1200person-mrem
- Goals Were Extremely Challenged

## What Is Next?

- Continue With the Chemical Analysis To Find Out About the Other Beta Components
- Results Will Tell If Instruments Need to be Recalibrated to Deal With This Type of Samples
- 18 New Samples On Storage Awaiting For Characterization
- Huge Task For HP To Help Scientists To Keep Exposures As Low As Possible
- To Understand All the Radionuclides Contributing To The  Accrued Exposures

## Thanks!!!

- Many Thanks to:
- Bill Stigberg –HP Tech
- Dave McGann- NE Tech
- Tatiana Burtseva and Mike Billone the main PI’s
- For helping us to collect  and sort all the data