ML19290E181
| ML19290E181 | |
| Person / Time | |
|---|---|
| Issue date: | 01/17/1980 |
| From: | Person L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Scarano R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-34 NUDOCS 8003050024 | |
| Download: ML19290E181 (3) | |
Text
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%'i UNITED STATES NUCLEAR REGULATORY COMMISSION 5
j WASHINGTON, D. C. 20555 JAN 171980 MEMORANDUM FOR:
R. A. Scarano, Chief Uranium Recovery Licensing Branch FROM:
L. S. Person Uranium Recovery Licensing Branch
SUBJECT:
TRIP REPORT ON MEETING WITH UNION CARBIDE CORPORATION TO EXAMINE NEW INFORMATION ON URAVAN TAILI. ':S EMBANKMENTS TIME AND PLACE:
Buffalo, New York, December 21, 1979 PARTICIPANTS:
NRC and Consultant Union Carbide and Consultant L. Person (NRC, WMUR)
D. Kapral (Union Carbide)
G. Castro (Geotechnical E. Kuntz (Union Carbide)
Engineer. sinc.)
J. Gill (Acres American Inc.)
R. Stuble (Acres American Inc.)
R. Henschel (Acres American Inc.)
R. Adams (Acres American Inc.)
L. Smolinski (Acres American Inc.)
J. Berry (Acres American Inc.)
PURPOSE:
This meeting was requested by the Union Carbide to submit additional infomation on Uravan tailings embankments for NRC review. This additional information is required before a safety analysis ccn be completed for Uravan embankments number 2 and number 3.
The short notification time for this meeting was the result of an effort to expedite a decision on whether the embankments, particularly embankment number 3 currently under operating conditions, are suitable for continued operational use.
Mr. R. Kapral of the Union Carbide Corporation began the meeting by explaining that Union Carbide was interested in providing additional -
infomation (developed by Acres American Incorporated) to NRC and Geotechnical Engineers Incorporated to aid NRC in making a recommendation on December 28 about the integrity of the Uravan tailings embankments.
R. Person of WMUR then explained that no December 28th date had been set for NRC's recommendations on the operational use of the Uravan embaniments but that an early detemination of the embankment stabilities was in the best interest of all parties concerned.
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8008050
R. A. Scarano.
Acres American Representative Jim' Gill ~then_ presented chronographs of piezometer data which under preliminary scrutiny appeared to give uncertain information on the performance of the ponds. As NRC had previously recommended, in a letter to the State of Colorado on December 14, 1979, G. Castro of Geotechnical Engineers then pointed out that in order to get meaningful data from installed piezometers that the frequency of piezometer readings should be increased, that observed levels should be estimated to the nearest tenth (to show any trends), and existing and future piezometers should be tested to determine their condition.
Results of static stability analysis were then examined which showed safety factors (for the ponds in their existing condition) for pond number 2 on the eastern slope to be 1.79 and pond number 3 on the northeast corner to be 1.35.
G. Castro then asked if, in light of the NRC Regulator:
Guide 3.11 recommendation of a static safety factor of 1.5, a safety factor of 1.35 should be considered adequate for pond 3.
Jim Gill of of Acres replied that it should be adequate considering that discharge to.
pond number 3 would cease in mid January.
G. Castro then pointed out that on his last site visit of December 17 he noticed that tailings liquid was imponded against the dike of pond number 3 which seemed to result from spigoting too close to the dike.
G. Castro also inquired what procedures Acres would follow to eliminate impounded liquid against the dike and if some technique such as multiple spigoting would help.
R. Kapral of Union Carbide stated that the discharge volume was not large enough to allow use of multiple spigots without clogging the pipes.
At G. Castros' request Acres presented aerial photographs taken in 1977 which show sloughing features at the toe of dam 3.
These same features were observed on site visits of October 30th and December 17th. After examining the photographs in detail, G. Castro expressed the opinion that no significant change appears to have occured since the original photographs'were taken.
During a discussion of various methods that could be used to improve the stability of pond 3 while pond 2 is being repaired, it was pointed out that the installation of horizontal drains where sloughing had occured would make significant improvements to these localized areas and would mitigate effects occuring in the toe of the embankment.
Verbal communication to R. Jones by telephone to Uravan revealed that sloughing had occured at the SE corner of pond 2 during a freezing and then thawing period.
In private consultation with L. Person, G. Castro pointed out that failure of the kind which took place in pond 2 could occur in pond 3.
~
R. A. Scarano.
G. Castro then explained that a sudden sloughing failure of the lower part of the slope could induce deformations (undrained) of the rest of the mass. Thus the stability would be determined by urdrained strength test as opposed to drained strength test as was used in earlier analysis.
Acres then submitted a copy of test currently being run at the University of Colorado on undisturbed samples which would be tested for undrained strength. At this point (1:30 pm) a telephone call was placed by R. Person and G. Castro to R. Scarano (WMUR) to inform him of what had thus far been discussed at the meeting and to recannend that the State of Colorado immediately take action with regard to the spigoting problem and the danger which exist at pond 3 because of the winter season.
It was also recommended that discharge be discontinued into pond 3 and that consideration be -given to installation of horizontal drains in known areas of sloughing.
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j L. S. Person Uranium Recovery Licensing Branch Division of Waste Management cc:
H. Fontecillo, OCM John C. Guibert, OCM Hugh L. Thompson, OCM George D. Sauter, OCM e
.