ML20126J161
| ML20126J161 | |
| Person / Time | |
|---|---|
| Issue date: | 12/27/1979 |
| From: | Rolonda Jackson Office of Nuclear Reactor Regulation |
| To: | Scarano R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML19211B053 | List: |
| References | |
| FOIA-81-8 NUDOCS 8104230758 | |
| Download: ML20126J161 (4) | |
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/[ jo, UNITED STATES
.y e j ' NUCLEAR REGULATORY COMMISSION ,
g s WASHINGTON, D. C. 20655 '
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MEMORANDUM FOR: Ross A. Scarano, Chief Uranium Recovery Licensing Branch, DWM THRU:
P James P. Knight, Assistant Director for Engineering, DSS FROM: Robert E. Jackson, Chief I Geosciences Branch, DSS ,
SUBJECT:
TECHNICAL ASSISTANCE REQUEST - RESPONSE T0 CHURCH '
ROCK INFORMATION REQUEST BY CONGRESSMAN UDALL (TAC 5294, R53)
PROJECT NAME: Church Rock - United Nuclear Corporation RESPONSIBLE BRANCH: Uranium Recovery Licensing Branch REQUESTED COMPLETION DATE: December 19, 1979 In reply to your memorandum of December 15, 1979 to James P. Knight requesting technical assistance, we have enclosed our response to question no. 8 of Congressman Morris K. Udall letter of December 6, 1979 to Chairman Joseph Hendrie.
The enclosed input was prepared by J. Kane of the Geosciences Branch.
We direct your attention to enclosure 2.of Frank Schroeder's letter of October 4, 1979 to Robert E. Browning and G. Wayne Kerr concerning draft congressional testimony. Pertinent portions of our response on pages 2 and 3 which discusses the applicable regul'ations covering tailings dam could also be incorporated into the response to question no. 8.
In view of our Branch's heavy workload that has been impacted by reduced manpower, including a loss of personnel to your Branch, we recomend that future technical assistance for the Church Rock project be obtained from your geotechnical engineering consultants.
O
, W W Robert E. Jacksmi, C ief j Geosciences B nch j Division of stems Safety
Enclosure:
As stated cc: w/o' enclosure R. Mattson F. Schroeder J. Martin i G. Kerr I cc: w/ enclosure See next page l l
45 l 810.4230738i l
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1 R. Sca.ano - 2 cec g 7 gm l
cc: w/ enclosure -
l J. Knight P, Jackson ll L. Hulman T. Sullivan L. Heller L. Reiter i J. Kendig J. Linehan J. Nelson J. Kane .
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l CHURCH ROCK URANIUM MILL TAILINGS PROJECT '
. TAC NO. 5294, R53 .
GE0 TECHNICAL ENGINEERING INPUT FOR RESPONSE i TO CONGRESSIONAL INQUIRY ,
PREPARED BY: JOSEPH 0. KANE, P.E.
NRR, DSS,.GB, GES Reference. Congressman Morris K. Udall December 6, 1979 Letter, Item No. 8.
Question United Nuclear Corporation representatives'at our hearing ]
stated that the Church Rock tailings impoundment met "all design ,
criteria established by the NRC," including Regulatory Guide 1.101.- Did the Church Rock facility meet all NRC's impoundment design criteria?
Response In the opinion of the Geotechnical Engineering Section staff, who was not recuested to conduct a review or to provide technical assistance until after the July 1979 dam failure, the design of the Churchr Rock facility does not meet all of ;
i NRC's impoundment criteria. The following areas in the design
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of the Church Rock facility are considered inadequate in meeting NRC criteria and conservative engineering practice. i
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- 1. Stability analysis. The results of stability studies completed ,
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by the Applicant prior to the. dam failure are not acceptable.
The results are unacceptable because the shear strengths adopted for the foundation soils and used in the stability studies did not' adequately anticipate the significant loss in shear strength caused by the wetting of foundation soils resulting from the tailings pond impoundment. The factors of safety computed in the submitted !
' stability studies are therefore, based on unconservative soil ;
shear strengths and a direct comparison cannot be validly made l with minimum factors of safety that are listed in Regulatory Guide 3.11.
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- 2. Settlement studics. The extent that settlement and :
potential crackirg within the retention embankment was i
addressed and rnalyzed in design was not suff'cient to properly estimate the magnitude of the settlement problem l
[ .over the collarsible foundation soils. A more detailed
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[ evaluation of settlement would likely have resulted in design measures that provided a satisfactory engineering solution :
i against harmful embankment' cracking. l t
- 3. Dam safety instrumentation. Basic instrumentation (piezometers I and movement devices) to monitor the retention embankment's performance and safety was not installed as suggested in {
In varying degree, design, construction and operation ir. adequacies continue to exist, even today. Outstanding geotechnical engineering issues as noted in recent safety reviews completed by the NRC j staff and its consultant remain unresolved for the Church :
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l Rock project. l
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