ML19256F668
| ML19256F668 | |
| Person / Time | |
|---|---|
| Issue date: | 12/04/1979 |
| From: | Krug M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Topp A NEW MEXICO, STATE OF |
| References | |
| REF-WM-25 NUDOCS 7912190785 | |
| Download: ML19256F668 (5) | |
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DEC 0 41979 Mr. Alphonso A. Tcpp, Jr.
Program Manager Environmental Improvement Division State of New Mexico P. O. Box 968 Santa Fe, New Mexico 87503
Dear Mr. Topp:
This letter provides documentation of a conference call on November 20, 1979, between us and Ray Waggoner of Bokum Resources Corporation. The purpose of the conversation was to obtain answers to radiological questions regarding the revised " Groundwater Discharge Plan Using Below-Grade Tailings Disposal" for Bokum's Marquez mill. Coments and questions regarding the geological and hydrological aspects of the proposal will be transmitted in the future.
A sumary of the questions and answers during the conversation is provided as Enclosure 1.
Additional questions and coments are outlined in Enclosure 2.
Please ask Mr. Waggoner to (1) review the information in Enclosure 1 for accuracy, (2) provide responses to outstanding items noted in Enclosure 1, and (3) provide responses to the items in Enclosure 2.
To assure the preparation of a thorough, knowledgable, and technically sound radiological impact evaluation, Bokum should be asked to compile the data outlined in Table A-1 of the draft regulatory guide provided as (" Calculational Models for Estimating Radiation Doses to Man from Airborne Radioactive Materials Resulting from Uranium Milling Operations,"
dated May 1979). This information was previously submitted by Bokum during March 1979.
However, as stated in previous conversations, this information needs to be revised to reflect the new proposal.
References to previously submitted infomation is encouraged.
Data assumptions, calculations, and justifications should be given. Without this complete compilation, the NRC staff will have to make conservative assumptions which perhaps would result in an overly conservative radiological assessment.
Mr. Waggoner's and your time and effort in responding to our questions and coments are appreciated.
Please contact me (301/427-4103) if you require any clarifications of the enclosures.
Sincerely, IQu 6.
Madonna E. Krug Uranium Recovery Licensing Branch
Enclosures:
As stated cc: Mr. Thomas E. Baca, w/o enclosures jg}7 3p}
Mr. Ray Waggoner, w/ enclosures 7 D12190 7gg
QUESTIONS AND ANSWERS REGARDING THE GROUNDWATER DISCHARGE PLAN, MARQUEZ MILL 1.
Q - Section 1.2, Source Tenns, of Appendix D states an average ore quality of 0.08 percent U 0, and the assumption that 93 percent of the uranium 33 is removed during the mill process. These values were previously given as 0.12 percent and 96.4 percent, respectively. Why have the values changed?
A - The revised estimates reflect current estimates.
NOTE:
These changes will necessitate a recalculation of the NRC source terms.
2.
Q - For the r;adon calculation in Section 1.2, Appendix D, a value of 2.03E4 m' is given for the tailing area exposed. This is equivalent to only five acres. Give the basis for this value.
A - The calculation is intended to estimate the maximum emanation, and thus assumes that 50 percent of each trench surface area is exposed at any one time (since reclamation proceeds while filling the trench) for two trenches. The most northern and southern trenches are assumed.
NOTE: Given the above answer, the total area should be ten acres.
Mr. Waggoner stated he would check on this.
3.
Q - The operational period for the mill should be given as 20 years instead of the 15 years cited and used for the assessment.
A - The +ime period should be 20 years. Where is it given in Appendix D?
NOTE: The 15-year period.is given on page 3 of the UDAD IX runs (0PTIME =
1.50E + 01).
4.
Q - For the UDAD-IX calculation in Appendix 0, only inhalation and external exposure pathways are considered. Why was the ingestion pathway not considered?
A - The ingestion pathway was considered; however, the inhalation and external exposure pathways were assumed to be the principal ones and much greater than the ingestion pathway. This assumption was made from a value judgment and based upon census data.
NOTE:
Justification, such as census results, should be provided for this assumption.
Previous, preliminary calculations by NRC show that the critical pathway is ingestion.
5.
Q - No inhalation doses from particulates are considered or presented for residents of Marquez.
Only limited distances are considered:
1, 10, 50, and 60 km.
In fact, for all the other type doses, except radon, the same distances are used.
The distances should reflect where the people are actually located.
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s A - Mr. Waggoner thought that the distances may be limited by the UDAD-IX code.
He indicated that he would find out the reason.
NOTE:
Any location at all can be considered by UDAD-IX.
Up to 60 free receptors can be considered.
6.
Q - Provide the process rate, estimated amount of dust released, and operating times (days / year, hours / day) for the ore crusher on the ore pad.
A - There will be no ore crusher, just a wet grinder.
7.
Q - What is the fraction of annual animal feed obtained by local grazing?
A - Local grazing is 100 pe'rcent. There are no supplemental feeds.
8.
Q - Do the facilities include a SAG mill? If so, the Nkr sor.ce terms will exclude a source term for grinding.
A - A SAG mill is included.
9.
Q - The total surface area of Trenches 2-6 is given as 132 acres (Design Memorandum 11, page 1). What is the surface area and depth of Trench l?
A - These numbers can be calculated with the data given in Table 1 of Design Memorar.dum 8.
10.
Q - According to Design Memorandums 8 and 11, Trench 1 has a capacity to acconmodate about one-half year of tailings; and Trenches 2-6 accommodates the rest of the tailings generated by the 20-year period (assuming a 65' depth for Trenches 2-6).
Is that all the capacity that is needed?
A - Yes.
- 11. Q - At what depth is the groundwater for the trench locations? This information is not in the Design Memorandums.
A - Groundwater information is given in Book 2, Appendix E.
The major aquifer in this area is the Tres Hermanos, located below the Mancos shale formation, which is approximately 350' below the bottom of the trenches.
12.
Q - What is the sequencing (i.e., amount of surface area exposed at different points in time) for the evaporation ponds and disposal trenches? Design Memorandum 12, pages 1 and 2, suggests that the sequencing is not known at this time.
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. A - Approximately 90 - 100 acres of surface area for the evaporation ponds will be exposed at any one time.
Each trench will be reclaimed as it is being filled.
NOTE:
It will be assumed that a maximum of about 25 acres of filled trench surface area will be exposed at any one time. This is equivalent to the averaae surface area for one trench.
Sequencing should be planned and provided to allow a more accurate radiological assessment.
- 13. Q - Wnat is the moisture content of the tailings in the trenches?
A - The tailings slurry to the trenches will contain about 46 percent solids. After dewatering, about 20 to 25 percent moisture will be retained.
- 14. Q - What provisions will be made for the design and reclamation of the evaporation ponds located over reclaimed trenches?
A - The reclaimed trenches will have a cover of approximately three meters.
On top of that will be an additional layer of about 30 to 35 feet.
Of the second layer, the evaporation pond (s) would be eight feet deep with a five-foot liner.
NOTE: Such concepts should be included in the final reclamation procedures.
- 15. Q - What evaporation pond capacity is needed? (Design Memorandum 10 states a total of 101 acres at a four-foot depth is needed for the 20-year mine life.)
A - For the mill life, a capacity of 90 - 100 acres at a seven-foot fluid depth is needed.
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ADDITIONAL QUESTIONS AND COMMENTS REGARDING RADIOLOGICAL ASSESSMENT, APPENDIX D, BOOK 2, GROUNDWATER DISCHARGE PLAN, MARQUEZ MILL 1.
In the " initial namelist indata values" for the UDAD code, default values should be used for XRHO and KRH0.
2.
Incorrect particle densities (and hete, inhalation dose conversion factors) are used for the various type sources, i.e., the yellowcake drying and packaging particle density should be 8.9 g/cm3 instead of 2.4 g/cm3
- Also, the settling velocity for the associated diameter should be 2.67E-4 m/sec instead of 0.0 m/sec.
Provide the justification for these values which deviate from the suggested values in NUREG/CR-0553, "The Uranium Dispersion and Dosimetry (UDAD) Code."
3.
No lead is assumed to be released from the yellowcake drying and packaging stack.
If this is an oversight, should secular equilibrium with radium be assumed?
4.
Locations for the tailings source term in the UDAD-IX printout do not correspond with the locations given in the design memoranda. According to one map, one tailings area is located northwest of the diversion ditch; and another is situated on the ditch.
Please clarify.
5.
The ipsol(10) solubility array is closely related to the pden(5), ptsz(5),
ptszfc(5,5) and sorce(10,*) arrays.
If one of these is changed, then one or more of the other arrays may need to be changed.
6.
It appears that the Leaching and CCD circuit X, Y coordinates given in Table 1 of Appendix 0 are incorrect.
Please veri fy these locations.
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