ML102160790

E-mail from John Hickman, NRC, to David Sokolsky, Pg&E, Regarding Humboldt Bay 20.2002 Request

ML102160790
Person / Time
Site:	Humboldt Bay
Issue date:	07/16/2010
From:	John Hickman NRC/FSME/DWMEP/DURLD/RDB
To:	Sokolsky D PG&E Corp
Hickman J
References
Download: ML102160790 (3)

Text

From: Hickman, John Sent: Friday, July 16, 2010 2:53 PM To: Humboldt Bay, David Sokolsky

Subject:

Humboldt Bay 20.2002 questions

Dave, I have some questions from my reviewer for your 20.2002 request. If you can address these issues during our meeting that will certainly help our review.

1. Are the concentrations in Table 1 maximum concentrations or average concentrations? The text on page 2 of Enclosure 1 to PG&E letter HBL-10-003 has conflicting information on this.

What variability in the concentration and relative ratios of radionuclides is expected in the waste?

2. How do you plan to verify the concentrations in the waste prior to shipment?

3. What is the basis for the amount of dilution of the waste assumed in the source term concentrations used in RESRAD? What is the basis for the assumed spreading of the waste (i.e., the area and thickness of the contaminated zone)?

4. According to information provided to the NRC as part of a different 20.2002 request (for waste from the Hematite site), the cover thickness at US Ecology Idaho ranges from 2.5 to 20 feet thick. A thickness of 11.8 feet is used in the RESRAD modeling for the Humboldt Bay 20.2002 request. The external dose from the radionuclides potentially present in the waste from Humboldt Bay Power Plant is much higher when the cover is thinner. The dose calculated based on the concentrations assumed in the RESRAD analyses provided by Humboldt Bay Power Plant may still be acceptable if the cover is thinner, but the dose through a thinner cover may need to be evaluated if the concentration or dilution assumptions change as a result of the answers to the above questions.

5. Can you provide the reference for the C-14 Kd values used?

6. What is the basis for the dimensions used in Microshield calculations? Also, why is the truck driver so far from the waste (4.8 m)?

7. Where does the number of repetitions come from for the stabilization worker and cell operator?

8. Is any clean out of the trucks performed?

9. The number of employees is less for the surveyor and stabilization worker than was assumed in the 20.2002 request submitted for the disposal of waste from the Hematite site at

US Ecology Idaho. Can you provide any explanation for why the number of workers is different in these two submittals when they both pertain to the same facility?

NRC staff also noted the following gaps or inconsistencies in information provided as part of this 20.2002 request. However, the following items do not appear to be risk-significant and do not need to be responded to:

- The value of PE assumed in the intruder calculation is based on a humid site, which is not consistent with the climate of US Ecology Idaho.

- The basis for the length parallel to aquifer is not provided

- The basis for using the plant/soil ratios to calculate the Kd values for Eu and Gd and the Kd for Cs-137 in clay (UZ1) is not provided.

- A number of parameters are not justified in this submittal, but the parameters are the same as those used in the Hematite submittal. Some examples of this include the inhalation rate and dust concentrations used in the calculation of the worker dose and the subsurface parameters used in RESRAD. NRC staff will depend on the justification provided in the Hematite submittal in their evaluation unless Humboldt Bay Power Plant submits their own justification for these parameters.

Thanks, John E-mail Properties Mail Envelope Properties ()

Subject:

Humboldt Bay 20.2002 questions Sent Date: 07/16/2010 2:45:17 PM Received Date: 07/16/2010 2:53:00 PM From: Hickman, John Created By: John.Hickman@nrc.gov Recipients:

DDS2@pge.com (Humboldt Bay, David Sokolsky)

Tracking Status: None Post Office:

Files Size Date & Time MESSAGE 11426 07/16/2010 Options

Expiration Date:

Priority: olImportanceNormal ReplyRequested: True Return Notification: True Sensitivity: olNormal Recipients received: