ML19363A009

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Disposal or Onsite Storage of Residual Thorium or Uranium (Either as Natural Ores or Without Daughters Present) from Past Operations
ML19363A009
Person / Time
Site: 07000925
Issue date: 10/05/1981
From: Dircks W
NRC/EDO
To:
Office of Nuclear Material Safety and Safeguards, NRC/OCM
Shared Package
ML19365A023 List:
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Download: ML19363A009 (39)
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Text

t i

October 5 1 1981

zL SECY 81-576 For
The Coan1ss1oners

-From: William J. Dircks Executive Director for Operations

Subject:

DISPOSAL OR ONSITE STORAGE OF RESIDUAL THORIUM OR URANIUM (EITHER AS NATURAL ORES OR WITHOUT DAUGHTERS PRESENT) FROM PAST OPERATIONS .

Purpose:

To inform the Corrm1ssion of the adoption of a Branch Technical Position for application by the Uranium Fuel Licensing Branch.

Discussion: Some of the sites fonnerly used for processing thorium and uranium are known today to be contaminated with resi~ual radioactive materials. In many cases, the total amount of contaminated soil is large, but the activity concentrations of radioactive materials present are sufficiently 1ow as to justify their disposal on privately owned lands or storage onsite rather than transport them offsite to a licensed -*---

  • radioactive materials disposal (c0fll1lereia1) site.

In many instances, packaging and transporting these wastes to a licensed disposal site would be too costly \.

  • and not justified from the standpoints.of risk to the public health or cost-benefit. Furthermore, because of the high volume of these wastes, limited cDttl'nercia1 waste disposal capacity, and restrictions placed on receipt of long-lived wastes at con111ercia1 sites; it is not presently feasible to dispose of these wastes at commercial low-level waste disposal sites.

Effective January 28; 1981. NRC regulations fn 10 CFR 20 "Standards for Protection Against Radiation" were amended (45 FR 71761-71762) to delete Section 20.304 which provided general authority for'disposal of radioactive material by burial in soi1. Under the amended regulations licensees must apply for and obtain specific NRC approval to dispose of radioactive materials in this manner under the provisions of 10 CFR 20.302.

CONTACT:

R. G. Page, ,:*1~s 42-74309

- ......,-4.

The Cormtis~ioners Guidelines for disposal or storage of low activity concentrations of thorium and uranium or uraniwn ore bearing wastes on privately owned lands are needed to deal with the contaminated site cases which are presently pending (Enclosure l}. To this end. the staff has identified five acceptable options for di.posal (under the prov1sions of LO CFR 20.302) or onsfte storage which the staff intends to apply in processing applications.

A ~U11111ary discussion of these is provided in Enc1osure 2.

': An expanded discussion is contained in Enclosure 4.

Enclosure 3 discusses the technical bases for the derived concentration limits for each of the four disposal options. The approach used in establishing the cancentrati on 1imi ts is consistent with that used in developing the proposed new Part 61 concerning licensing requirements for land disposal of radioactive wastes. That proposed rule 1s based on two assumptions that a burial site may some* day *be intruded; and that buried radioactive materials will not likely present a danger to the public health and safety even if intruded.

In the case of urani~ ore residues with daughters present, there will be limited radon emanations; however, with the burial depths required, resultant surface f1uxes will be nea~ background levels * .Accordingly, the burial of radioactive materials co~ered by the Branch Technical Position does not present a clanger to health and safety.

We believe that the options for disposal or storage of thorium or uranium are fully consistent with disposal standards recommended by EPA. We infonna11y discussed the options with EPA staff members and made some changes to accoumodate their suggestions.

Before approving an application to dispose of thorium qr uranium under options, 2. 3. or 4, we will so1ieit the views of appropriate State health officials on a case-by-case basis. In this connection, we sent the States a copy of the proposed Branch Technical Position. Two States commented; neither of which were negative.

< ******** O-:- OOOO ~-- *.. ,..: ...:. -::. :*.*.,, ~ **~-:. ~7 "*ooooO:.::-.:- *

    • * ..... M

The Conmissioners Enclosure 4 is a Federal Register notice which we plan to have published on this matter.

~~..t-Willi am J. Dircks Executive Director

    • .r

'\ 1 for Operations

Enclosures:

1. Contaminated Site Cases Presently Pending
2. Summary of Disposal and Storage Options J. Calculation of Allowable Concentrations for Four Disposal Options
4. Federal Register Notice DISTRIBUTION Commissioners Commission Staff Offices SECY

\

ENCLO~URE l

Contaminated Site Cases Presently Pending Disposal or Storage Option that May Applv

~ Stepan Chemical Company

.I \Maywood, New Jersey (Thorium ore residues)

Kerr-McGee Corporation 5 West Chicago, Illinois (Thorium ore residues)

McGean Chemical Company 4 Newburg Heights, Ohio (Depleted uranium)

/'wax Corporation 4 or 5 Parkersburg, West Virginia (Thorium oxide mixed with zirconium)

Cotter Corporation (fonner owner) 5 Latty Avenue .

" St. Louis, Missouri (Uranium residues)

Ve1sico1 Chemical (formerly Michigan Chemical) 4 St. Louis, Michigan

{Uranium, thorium and radium ore wastes

  • Except for a few hot spots that will need to be removed from the site,. the contamination on adjoining property west of Highway 17 appears to fall under options 2 or 3.

Enclosure 1

~ ................

\

ENCLOSORE 2

SUMMARY

OF DISPOSAL AND STORA.GE OPTIONS The following is a surrrnary of the disposal and storage options which staff intends ta apply. The maximum concentrations permitted under each disposal option_ are tabulated on the last page of this enclosure.

.... , 1. Disposal of acceptably low concentrati~ns {which meet EPA cleanup standards) of natural thorium, depletett or enriched uranium. and

,; uranit1n ores with no restriction on burial method.

The concentrations specified for this option are believed acceptably' low without restricting the method of burial. It is expected. however, tha currently licensed operations will be conducted in such a manner as to minimize the possibility of soil contamination and when such occurs the contamfnation will be reduced to levels as low as reasonably achievable.

2. Disposal of certain low concentrations of natural thorium and depleted or enriched uranium (with no daughters present) *when buried under.

prescribed conditions with no land use restrictions and no continuing NRC licensing of the material.

Under this option. burial ,will be permitted only if it can be demon-strated that the buried materials will be stabilized in place and not be transported away from the site. Acceptability of the site for disposal will depend on topographical, geological, hydrological and meteorological characteristics of the site. At a minimum, burial depth will be at least faur feet below the surface. *

3. Disposal of low concentrations of natural uranium ores with daughters in equilibrium, when buried under prescribed conditions in areas ~oned for industrial use, and the recorded title documents are amended to state that the specified land contains buried radioactive materials and* are conditioned in the manner acceptable under state law to impose a covenant running with the land that the.specified land may not be used for residential building. (There is no continuing NRC licensing of the materi a1.)

Disposal wi11 be approved if the burial criteria outlined in option 2 (including burial at a minimum of four feet) are met. Under this option, no residential building would be permitted over land where natural uranium ore residues have* been buried.

I Enclosure 2

'I

- .. _.,....... ---- ..--,~ ...

- 2 ..

4. Disposal of land-use-limited concentrations of natural thorit.111, natural uranium and depleted or enriched uraniim1 when buried under prescribed conditions in areas zoned for industrial use and the recorded title docwnents are amended to state that the land contains buried radioactive

, material s, and are co nd1 ti oned in the manner required by state 1aw to impose a co;1enant running with the land that the land (l) may not be excavated below stated depths in spec1fied areas unless cleared by appropriate health authorities, (2) may not be used for residential or industrial building, and (3} may not be used for agricultural purposes.

(There is no continuing NRC licensing of the.disposal site.)

Criteria for disposal under these conditions f.s predicated upon the assumption that intentional intrusion is 1ess likely to occur if a warning is given in land* documents of record not to excavate below burial depths in specified areas of land without clearance by health authorities; not to construct residential or industrial buildings on the site; and fK>t to use specified areas of land for agricultural purposes. In addition to meeting the burial criteria in option 2, recorded title doctµnents would be amended to impose these land use restrictions.

5. Storage of licensed concentrations of thorit111 and uranium onsite pending the availability of an appropriate disposal site.

When concentrations exceecvthose specified in option 4, long tenn disposal other than at a licensed disposal site will not normally be a viable option under the pr9visions of 10 CFR 20.302. In such cases, the thorium and uranium may be pennitted to be stored onsite under an NRC license until a suitable method of disposal is found. License conditions will require that radiation doses not exceed those specified in 10 CFR Part 20 and be main-tained as low as reasonbly achievab1e.

C"*

~ 3 -

SUMMARY

OF MAXIMUM CONCENTRATIONS PERMITTED UNDER DISPOSAL OPTIONS Diseosal 0Etions tpCi/gm)

Kind of Material la 2 3C 4d Natural ThoritDD (Thr-232 + Th-228) 10 50 soo-**

  • with daughters* present and in equilibrium

.(

""Na~~al Urani\111 (U-238 + U-234) with daughters present and 10 40 200 in equilibrium Depleted Uranium o Soluble 35 100 1000 o Insoluble 35 300 - 3000 Enri~hed Uranium o Soluble 30 100 ... 1000 o Insoluble 30 250 2500 a Based on EPA cleanup standards *.,

b Concentrations based on limiting individual doses to 170 mrem/yr.

c *concentration based on limiting equivalent exposure to 0.02 working level or 1ess.

d Concentrations based on limiting individual doses to 500 mrem/yr and, in case of natural uran1.wn. limiting exposure to 0.02 working l eve 1 or 1ess. ** * -*

.I

\

EMCLOSURE 3

\

(

    • ---~- ..... . . .

-~-

CALCULATION OF ALLOWABLE CONCENTRATlONS FOR FOUR DISPOSAL OPTIONS I Introduction The following ~ections provide dose ca1culations for establfshing limiting concentrations of thorium and uranium for dispo*sal under four disposal options. The dose tabulation includes various significant pathways to man resu1 ting from the burial of radioactive wastes containing na.tural thorium, natural uranium, enric~ed uranium, or depleted uranium. With these tables~ the concentration limit of a radionuclide or mixture of radionuclides in various types of wastes to be disposed of by these options can be calculated. Tables 7 and 8 suurnarize the concentration limits of sane typical wastes for each option of disposal. Concentration limits involving other mixtures of these radionuclides can be calculated by the use of these tab1 es.

II Radioactive Character1stics of the Nuclides A. Thorium The natural thorium decay chain and the characteristics of each nuclide are summarized in Table 1. The parent Th-232 generally exists in nature with its daughters which are in radioactive equilibrium with the parent. However, in some types of waste such as from processing of thorium ore, the purified meta1 {Th-232 and Th-228) is removed as the product and the daughter products can be various wastes. Therefore, i t is itt1)ortant to unde'fstand the history of the' operation and how the wastes are generated.

As shown in Table 1, Th-232 and its daughters consist of alpha, beta, and ganma emitters. The alpha emitters will constitute a significant pathway for dose tc man through inhalation and ingestion. The ~ritical organs in the i nha1ati on and ingestion pathways are the lung and the bone depending on the so1ubi1ity classification of the nuclide. The gamna emitters will contribute external radiation (whole-body) dose to man. Therefore, the pathways for dose to man to be consi,dered for natural thorium are direct radiation~ inha1a~jon and ingestion.

Enclosure 3

I*'-

4-Table 1 Thorium Chain

  • - ,. .a .._ - *
  • Princi~a(*aadigt1ons (MeV)a

~

Isotope Th-232 1112 1.405x1010y Daughter Ra-228 Ai pha:0 .

4.00 Seta

-

  • Gammac J

Ra-228 5.75y Ac-228 -~- 0.010 ..........

Ac-228 6.13h Th-228 -- 0.376 0.91 S Th-228 1.9131y Ra-224

'\

5.40 --- 0.002 Ra-224 3.66d Rn-220 5.67 --- .. . --- -

0.009 Rn-220 55.Bs Po.;.215 6.29 .........

~

Po-216 0.1Ss Pb-212 6.78 ---

Pb-212 Si-212 10.54h 60.55m Bi-212 n . . 20a 6.04(35.93C:.)

0.100 0.117 0.003 Po-212 -(64.071) 0,717 0.281 r1~2oa 3.07m Pb-208 -- 0.561 2.37 Po-212

.7 3.0Sxl O s . Pb-208 8.78 ----

(Stable} -

a Branches <li not included.

b .

Average energy.

c Tota 1 Energy emitted per .d isi ntegratfon *

    • _ . . _ _ .. _ .. _ _ ** - - - .... . . - . . - , L ... - - . ... * - .. - - .. ..... ..

B. Uranium The uranium chains including U-238 and U-235 are given in ;ables 2 and 3. ,For uranium that has been processed through the milling operation, the only nuc11des of importance fn the dose calculations are U-238 and U-234. The buildup of. daughters in the separated uranium is not important. f.e., neither the Th-230 nor the Ra-226 could reach 101 of equi11brium with the separated uranium until greater than 10,000 years. The U-234 usually *stays in equilibrium.

with the U-238 parent with the equilibrium between U-238 and Pa-234 reached in a matter o..f months. In nonnal processing of uranium ore, the process separates both the Th-230 and Ra-226 to the s~ stream of waste: then both nuclides f are in secular equilibrium.

If fn the case of uranium residues Th-230 and Ra-226 are not in equilibrium. particularly if the Th-230 is much higher than Ra-226, a potential source of Ra-226 contamination may exist as radium builds up to equilibrium with the Th-230. In this case, the primary con-sideration must be given to exposure from radionuclides other than U-238 and U-234.

In some types of operations7 other metals are extracted-and uranium ore is left in the waste stream as byproducts. In these cases all uranium daughter products.must be considered.

The parent U-235 occurs to the extent of only about 0.7i 1n natural uranium and the chain fs generally unimportant compared with the U-238

.. chain. Howevtr, in the early years of the Manhattan Project much of the ore was very high grade pitchblende or carnotite ore. After the uranium was separated and Ra-226 extracted from the wastes, the Ac-227 and Pa-231 nuc11des remained in the waste stream. These constitute a significant source of contamfnation.

As shown in Tables 2 and 3. radionuclides in the uranium decay chains emit alpha, beta and gamma radiation. The pathways for dose to man are from direct radiation, inhalation and ingestion. The critical organs are th~ whole body. the bone and the lung.

_ .. , ......... - ...................... _ ........... - ... 4

  • _ ,_ _ _ _ _ _ .... ~.,......, _ _ _ .... _ _ _ _ ......... - .... - - - . , . . _ _ . . . _ . - .... - - ~ - __ .._ _ _ _ _ _ _ . . . . . . . --

Table 2 Uranium Chain 1

bPrincieal Radigtions {MeV)a

~.IsotoEe 1/2 Dau2hter Alpha Beta Galtll'lac

.I t 9 Th-234 4.20.

u-238 4.468x10 Th-234 24. 10d Pa-234 --- 0.044 0.008 Pa-234 1.17m U-234 0.82 0.011 U-234 2.44sx105y Th-230 4.76 ........... . ........

To-230 7.7x104Y Ra-226 4.66 --- ----

Ra-226 1600y Rn-222 4.77 0.006 Rn-222 3.8235d Pa-218 5 **9 Po-218 3.05m Pb-214"'

/

6.00 ---~ ..........

Pb-214 26.Sm Bi-214 ~ ..... 0.22 0.23 Bi-214 19.9m Po-214 0.63 2.03 Po-214 4 1.64x1 o* s Pb-210 7.69 ..... ----

Pb-210 *22.Jy Bi-210 - ----- 0.007 0.002 81-210 5.012d Po-210 0.39 Po-210 138.378d Pb-206 5,31 -~--

  • (stable) aaranches. <li not included bAverage ednergy.

crotal energy emitted per disintegration.

Table 3 Actinium Chain I l~inciEal 'Radiations (M~V)a

~ Isoto2e --"!a Dau2hter A1 pha Beta a Gantna c u-235 7.1 x108y Th-231 4.28 -*-- 0.140 Th-231 25.52h Pa-231 --- 0.078 O.Ol7 Pa-231 3.248x104y Ac-227 4.92 --- 0.030 Ac-227 21. 773y Fr-223 4. 19 (l

  • 38S) --- ----

Th-227 ----(98.62l) 0.010 Th-227 18. 718d Ra-223 5.67 0.010 Fr-223 21.Sm Ra-223 ..... 0.345 0.051 Ra-223 11 .434d Rn-219,. 5.70 ...... 0 .. 087 Rn-219 3.96s Po-21S 6.81 --- Q.054 Po-215 1. 780x10 ... 3s Pb-211 7.39 Pb-211 36. lm B1-211 0.453 o.oso Bi-211 2.13m TI-207 6.55 ........ 0.043 Tl-207

  • 4.77m Pb-207 ........ 0.493 0.002 (Stab1e) aBranches <li not included.

bAverage energy.

C,.otal energy emitted per disintegration.

....... -* ** 1 * .... * .. -* ............ *-

\

~III Dose Ca1culation The following Tables 4-6 sunJM.rize th~ Qrgan doses for various pathways to man based on unit concentration of each nuclfde as shown in Tables 1-3.

All internal doses listed in the tables are SO-year dose connitments; that is,, the total dose an indivici.tal will receive .from one year .

of intake integrated over the next 50 years of his life. For those J

~materia1s that either have short radioactive half-lfves or are eliminated rapidly from the body, essentially all the dose is received in the same year that the radionuclide entered the body, and the annual dose rate is:

about the same as the 50-year dose connitment. All external doses are given as annual dose rates.

The factors for converting internal exposure to dose (dose conversion factors) were determined using ICRP-2 and other recognized values and implemented by r~~~nt models (Task Group Lung Model) for the lung and GI tract. The dose conversion factors used for external radiation dose determination are. given in ORNL-4992. The dose conversion factor for inhalation of radon and its daughters are -derived from the BEIR report.

IV Derived Maximum Allowable Concentration for-Various *Disposal Options Tables 7 and 8 sunmarize the ma*x1mum allowable concentration for the disposal of various types of wastes. Concentrations derived in oo.t.ian.-1..__are ..r.e~i.du.es..

of cleanyp .. conceo:trsti.QD.l w_bj~ca.n._b~ ~spo*se.a. of 1n anv ..m~mu~r__._ The concentra-t1 ons derived in option Z are such tnat under the worst mdes Of exposure including all significant pathways. *the maxi111Jm individual dose would not exceed 170 mrem/yr to any critical organ. In option 3. the most significant pathway is from the inhalation of radon and its daughter products. With a~ average concentratio~ of 20 pCi Ra-226 per gm of waste, it is estimated that an fndiv1dua1 could be exposed to an average of 0.04 Working Level (WL) from inhalation of radon inside structures built on contaminated land.

This exposure is judged to be too high for residential use of the burial

  • site. (Co~are with 0.033 WL-10 CFR 20; o.oos-0.02 WL-EPA Florida Phosphate Guidance.) Comnercial use of the site is allowable because the exposure time to radon is expected to be less than SOI of continuous exposure and consequently no individual will likely be exposed to an average of 0.5 ~LM.

The concentrations of uranium, depleted uranium and natural thoriunt'derived in option 4 are higher by approximately a factor of 10 since a limited exposure from an intruder (assuming about 301 of full exposure used in option 2) is assumed and a maxinum indivi<i.lal dose of 500 mrem/yr to a critical organ is assumed. For the case of natural uran1um, tfte concentration derived in option 4 is higher by a factor of 5. The concentration 1s based on a limited exposure such that no individual will be exposed to a radon dose in excess of 0.5 WLM assuming a maximum exposure time of 2.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> (i.e. lOt) a day. This ls equivalent to continuous exposure to 0.02 WL.

)

Table 4 i

  • I figures are based on a unit concentratfBY of 1 pCt/g for .each radionuclide 1n son. .

Whole body dose* Whole body .dose Whole body dose Rad1onucl1des (mrem/yr) Radionucl1des (mrem/xr> Rad1onuc11des {mrem/yr) *

  • 1.lE--1 Pb.:..212 3.0£-1 Po-218 Pb-211 9.4£-2 81-212 2.3£-1 Pb~214 ..., 4.8E-1 81-211 9.4E-2 Tl-208 5.5E-O 81-214 2.0E-0 Tl-207 Po-214 Pb-210 3.4E-2 Bi-210 Po-210 (a) Assumed structural shielding factor of 0.5 and soi occupancy.

(b)The ground is modeled as a plane area with unifonn distribution of radioactivity.

  • Assume a soil density of 2.5 g/cc.

( C) 1RS i gn.1f1 cant compared With other nuc 11 des.

(d) * -2 Read as 2.5 x 10 *

-a-Table Sa Dose cw:1:~r~1:~(&f°'G.!h~~~~in~ie:e~~~~ended Figures are based on a unft concentration of 1 pCi/g of each radionuclide in soil. (Clearance rate class Y;.

particle size {AMAD)

  • 1 llffl)

--.ltadfonuc 1i de Dose conmftment

.t (mrem) f)

Uranium Series

-Bone woridng Level U-238 S.2E-3 Th-234 Pa-234a U-234 6.9E-1 5.SE-3 Th ... 230 6.7E-1 Z.4E-1 Ra-226 1.2E-z<el 3.6£-2 Po-218 Pb-214 Bi-214 Po-214 Pb-210 *7.9E-3(e) 3.1 E-2 Bi -210 Po-210 5.. 9E-2 Rn-222 (a)Fifty-year dose conrn~tment for one year of intake.

(b)Assumed resuspension facto..- Sx10*9 nrl; maximum soil density of 2.5 g/cc; 80% occupancy. This resuspension factor may be conservative. These factors should be based on particle size and densities associated with specific sites. *

(c)Read as 6.1x10*1

(d)Insigniffcant c~pared wfth other nuclide~.

( e) Ra-226 and Pb-21.0 are cl ass i fi ed as W compounds; Po-210 is c1 ass i fi ed as W or 0 compound.

{f) Based on quality fac-~r of 20 for alpha particles.

( 9) Pulmonary 1ung (h) The average Working Level (WLl .. h calculated on the basis of 25 WU1/year per WL (continuous exposure) and a aose conversion factor of 5 rem per working level month. This mean level of exposure derived from radon insf de a. structure built on contaminated was~es could.be off sfgn1ficant1y depending on the input parameter1 used, *such as the ventilation rate, type of floor. etc ** whic;h are dependent on the structural design of the *buila.in~. * .

. _........... ~~ ...

Table Sa (cont'd)

~aai onucil l ae Dose Commitment (mrem)

---...*, Lung Acti n, llm Seri es

-Bone U-235 6.2E-1 S.3E*3 Th-231 Pa-231 7 .. 6E*l 7.OE-1 Ac-227 1.3E-O 3.. 9E*l Th-227 8.SE-2 2.9E-4 Ra-223 5.9E-2 7.0E-4 Rn-219 Po-215

-~-- ----.-

Pb-211 Bi-211 Tl-207 Thoriµm Series

. Th-232 5.SE-1 2.6E-1

  • Ra-228 6.2E-3 2.lE-2 Ac-228 Th-228 Ra-224 -9.2E-1

...... 2.3E-2 Rn-220 Pb-212 - ---~ ......

Bi-212 Tl-208 4-._._ ..

. ,o.

I Table Sb Dose Conmitments From InfiaiatiOn of Resuspended Radionuclides From Contami-nated So11

\.! . .

F1gures are based on a uni~ concentration of 1 pCi/g of each radionuclide in soil (clearance .rate class W; particle size (AMAD)

  • 1 µm)

~aai onuc:1, ae Dose Commitment (mrem)

U'ran, um Se.ri es Lung Bone working Level U-238 6.3E-2 l.SE-2 Th-234 Pa-234a U-234 7.0E-2 1. 7£-2 Th-230 6. 9£:2 6.0E-1 Ra-226 7.2E-2 3.6£-2 Po-218 Pb-214 Bi-214 Po-214 Pb-210

  • 7.9E-3 3.1£ .. 2 Bi-210 ...........

Po-210 1 .3E-3 .5.9E-3 Rn-222 .002

Table Sb

{cont'd)

Radi onud i de Dose commitment

{mrem)

I

') Lung Bone Actinium series 0-235 6.4E-2 1.SE-2 Th-231 Pa-231 ----- ----

1.6E-O Ac~z27*. 7.4E-2 l.1E-O Th-227 6.8E-2 2.6E-3 S.9E-2 7.0E-4 Ra-223 Rn-219* ..._..

, *Po-215__., .. _,, -.

Pb-211 ----- ---

.. - --*--~-. ____ _.

_, ____ 2.1 E-2 Ac-228 ... _..

Th-228 1. SE-1 1.3E-1 .

Ra-224 Rn-220 -----_.

Pb-212 Bi-212 r1~2oa

Table Sc

\

nose Commitments from Inhalation of Resus¥ended 1 Rad,onuc1ides from contaminated So,

~ Figures are based on a unit concentration of 1 pCi/g

.I I of each radionuclide in soil. (Clearance rate class

'. O; particle sfze (AMAOu 1 ~ml)

R:aa1onucl1cfe Oose Cormn,brient (mrem) working Level Lung Bone Uranium Series U-238 1 .1 E-3 s.0£:..2 Th-234 Pa-234a U-234 1.2E-3 5.6E-2 Th-230 6.9E-2 6.0E-1 Ra-226 7.2E-3r 3.6£-2 Po-218 Pb-214 Bi-214 Po-214 Pb-210 \ 7.9£*3

3. lE-2 Bi-210 Po-210 1.3£-3 1.9£.:.3 RR*222 -002
  • ~ :

.. ~- ....--** ... . .

Table Sc (cont'd)

R:aa:, onucl, ae l

Dose commitment

~ {mrem)

' . Cung Bone

~ct1n1um Series U-235 1. 1 E-3 5.0E-2 Th-231 Pa-231 7.4E-2 1.6E-O Ac-227 l .1 £... 1 1,lE-0 Th-227 6.8E-2 2.6E-3 Ra-223 S.9E-2 7.0E-4 Rn-219 Po-215 ..... ........

Pb-211 Bi -21 l.

--~--

Tl-207 ~

Note: Thorium compounds are classified as Y and Wcompounds *

.. ** -:a.. .. *-........... .. ... ~........ - - -

)

-Table 6 .

Dose C0D111itment Resulting from Ingest1on(a)

(ve,etation, beef. milk) of Rad1onuc1 aes from Contaminated sofl.

  • Figures based on a unit concentratfon of 1 pC1/g of each nuclide in the soil (the first 15 cm of soil)

Bone Dose Bone Dose Bone Dose Radfonuc11des (mrem) Rad1onuclides (mrem) Radionuclides (mrem)

Uran1um Series Actinium Series Thorium Series U-238 1.6E-0 U-235 1.. BE-0" Th-232, 5.0E-1 Th-234 Pa-234 Th-231 Pa-231

  • 1.4E+1

~ Ra-228 Ac-228 5.4E-O U-234 2.0E-0 Ac-227

Po-210 3.3E-2 (a)lt fs assumed that an fnd1vfdua1 would raise 601 of his own food on the burial

'I site. The sJaff believes this to be -a conservative assumption since it 1s highly unlikely that an individual would raise this amount of his own food on a burial site.

")

)

Table 7 Sunmary of Radionuclide Concentrations In Wastes*Under Various Disposal Options Type of wastes ' * ' Option 1: Obt1ons 2 and 3 O~t1on 4 Whole-Body lung Bone Whole- ody Lung Bone Whole-Doily [ung Bone (10µr/hr) (lmrad) (3mrad) (170mrem) (170mrem} (170mrem) (500mrem) {500mrem) (500mrem) tfaxfmum Allowable Concentratfon (pCi/gm} *- -

1. Depleted uranium
a. Insoluble 35 _..... _ --- ....-
  • 300 ---- ... ........... 3,000
b. Soluble 35 ------- ---- 100 ,,., ............ 1,000

'\

2. Enriched uranium .,. __ ....
a. Insoluble 30 ------ ...... .- .. 250 ...... -.- .. ___ 2.soo
b. Soluble ----- I 30 ........ _ .. .. -

~ 100 1.000

3. Natura1 thorium (Th-232. Th~228)

(includes all daughters)

a. Insoluble 10 50 500
b. Solu~le 10 50 500
4. Natural urantum (U-238. U-234)

(includes all daughters)

a. Insoluble . 40 ( 2 ) 200 (l}

1 10< >

b. Soluble 40 200 i.

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(l)The residual cleanup conce~tration for natural uranium 1s based on that set by EPA (46 FR 2556-2563) for radium 226 and its decay poducts.

C 2>1ndoor radon exposure is estimated to be about 0.04 WL for continuous exposure; land restrfc;ion for residential use is required.

(J)Radium con~entratton is based on a limited exposure such that no individual will be exposed to a radon dose 1n excess of 0.5 WLM assuming a maximum exposure time of 2.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> a day. This 1$ equivalent to continuous exposure to .02 W~ *. .

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Table 8 Maximum Allowable Concentrat1on in Waste for Options l, 2. 3 and 4 Type of Wastes Maximum Allowable Concentration (pCi/g}

Option 1 Option 2 &3 Option 4

1. Depleted Uranium (U-238)
a. Inso1 ubl e 35 300 3,000
b. Soluble 35 100 ,.ooo
2. Enriched Uranium (U-238, U-235, U-234}
a. Insoluble 30 250 2,500
b. Soluble 30 100 1,000
3. Natural Uranium (U-238, U-234)
a. Inso1 ub1 e 10 40 200
b. Soluble 10 40 200
4. _Matural Thorium (Th-232; Th-228}

-a... Insoluble -,o 50 5_00 b:. Soluble 10 50 500

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ENCLOSURE 4

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NUCLEAR REGULATORY COMMISSION 7590-01 DISPOSAL OR ON-SITE STORAGE OF THORIUM OR URANIUM WASTES FROM PAST OPERATIONS AGENCY: Nuclear Regulatory Comnission (NRC) l ACTION: Discussion of Options for NRC Approval of Applications for

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Disposal or Onsite Storage of Thorium or Uranium Wastes -

Interim Use and Public Conrnent

SUMMARY

This notice discusses five options for NRC approval of disposal or onsite storage of thorium or uranium wastes from past nuclear operations.

The options are contained in a Branch Technical Position for administration by the Uranium Fuel Licensing Branch. -Division of Fuel Cycle and Material Safety*. Office of Nuclear Material Safety and Safeguards.

DATES: Conments on the options for disposal or onsite storage of thorium or uranium are encouraged. Such comnents will be considered in any subsequent revision of the Branch Technical Position. Comnents are due

~ Comments received after the expiration date will be considered if it is practical to do soi but assurance of consid.-

eration cannot be given except as to conments filed on or before that date.

FOR ADDITIONAL INFORMATION CONTACT: Ralph G. Page, Chief, Uranium Fuel Licensing Branch, Division of Fuel Cycle and Material Safety, Offjce of Nuclear Material 'safety and Safegu~rds, *Washington, D.C. 20555.,

telephone 301-427-4309.

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SUPPLEMENTfRY INFORMATION:

I. Introduction Some*of the sites fonnerly used *for processing thorium_a'l_d J

uranium are known today to be contaminated with residual radioactive materials*. SQTie are currently covered by NRC licenses. Others were once licensed, but the licenses to possess and ,use material have expired. In many cases, .the total amount of contaminated soil is large~ but the activity **-

concentrations of radioactive materials are be1~eved sufficiently low to justify their disposal on privately owned lands or storage onsite rather than their transport to a licensed radioactive materials d,,isposa1 (cOt1111ercial) site. In many instances packaging and transporttng these wastes to a licensed disposal site would be too costly and not justified fr9[n the standpoints of risk to the public health or cost-benefit.

Furthennore, because of the total vo1 ume of these wastes*, 1imited canmercial waste disposal capacity, and restrictions placed on receipt of long-lived wastes at conmercia1 sites, it is not presently feasible to dispose of these wastes at commercial low-level waste disposal sites.

Effective January 28, 1981, NRC regulations in 10 CFR 20, nstandards for Protectio~ Against Radiation", were amended (45 FR 71761-71762) to delete Section 20.304 which provided general authority for disposal of radioactive materials by burial in soil. Under the amended regulations, licensees

must apply for and obtain specific NRC approval to dispose of radioactive materials in this manner under the provisions of 10 CFR 20.302. A case-by-case review was believed neede<!__to

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assure that burial of radioactive wastes would not present an

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.... unreasonable health hazard at sane future date

  • The deleted provisions of Section 20.304 previously permitted burial of up to 100 millicuries of thorium or natural uranium at any one* time, with a yearly limitation of 12 buria 1s for each type of material at each site. The only ~isposal standards specified were (1) burial at a minimum depth of four feet, and*

( 2_} successive burials separated by at 1east six feet. Thus a total of 1.2 curies of'these materials were pennitted to be disposed of each year by burial in a 12 foot by 18 foot or larger plot of ground.

Under the amended regulations. it is incumbent on an applicant who wants to bury radioactive wastes to demonstrate that loc~l land burial is preferable to other disposal alternatiyes. The evaluation of the application takes into account the following infonnation:

  • Types and quantities of material to be buried

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- 1~ackaging of was~e

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- Burial location

- ~characieristfcs of burial site

-. .: Depth of burial I

- Access restrictions to disposal site

- ~Radiation safaty procedures during disposal operations

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  • Recordkeeping

- :-Loca1 buria 1 restri cti ans, if any For applications involving disposal of soi1s contaminated with low level concentrations of thorium and uranium (other tp~n concentrations not exceeding. EPA cleanup standards)i the matters of principal importance are:

- Concentrations of thorium and uranium (either in secular equilibrium with their daughters or without daughters present)

Volume of contaminated soil I - Costs for offsite and onsite disposal Avai1abi. lity of offsite burial space Disposal site characteristics

- Depth of burial and accessibility of buried wastes State and local governnent views II. Branch Technical Position There are five acceptabl~ options for disposal or onsite storage of thorium and uranium contaminated wastes. Applications for disposal or,storage will be approved if .the guidelines discussed under any option are met. Applications for other methods of

disposal may be submitted and these will be eva1u~t~ on their own merits.

1. Oinposal of acceptably low concentrations*(which mee.t EPA

~ cleanup standards) of natural thorium with daughters in secular equilibrium, depleted or enriched uranium, and uranium ores with daughters in secular equilibrium with no restriction on burial method~

Under this option, *the concentrations of natural thorium and de~leted or enriched uranium wastes are set sufficiently low that no member of the public is expected to receive a radiation dose ca,mitment fran the disposed materials. in

  • '* o I excess of 1 millirad per yea~ to the lung or 3 mi1lirads per year to the bone fran inhalation and ingestion, under any foreseeable use of the material or property. These radiation dose guidelines were recomnended by the Environmental Protection Agency* (EPA) for protection against transuranium elements present in the environment as a result of unplanned contamination (42 FR 60956-60959).

rn addition, the concentrations are sufficiently low so that no individual may receive an external dose in excess of* 10 microroentgens per hour above background. This is compatible with guidelines EPA proposed as cleanup standards for inactive uranium processing sites (46 FR 2556-2563).

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For natural uranium ores having daughters in equilibrium, the concentration 1imi.t is equal to*that set by the EPA*

(46 FR 2556-2563) for radium-226 (i.e., 5 pci/gm, in.9luqing I

background) and its decay pl"Oducts.

I The concentrat1ons specified below are believed appropriate to apply. tt is expected, however, that currently licensed operations will be. conducted i"*such a manner as to minimize the possibti ity of soil contamination and when such occurs the contamination wi11 be reduced to levels as low as reasonably achievable.

Kind of Material , Concentration (pCi/gm)

Natural thorium (Th-232 plus Th-228) if a11 daughte~s are present and in equilibrium 10 Depleted Uranium 35 Enriched Uranium 30 Natural Uranium Ores (U-238 plus U-234) 10 if all daughters are present and in

. e.quil ibrium The analysis upon which the Branch Technfca1 Position is based is available for inspection at the COITl'nission*s Public Document ~oom at 1717 H.St., N.W., Washington, D.C.

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The concentrations specified under this option may be compared with naturally occurring thorium and uranium ore

  • concentr.ations of 1,3 pCi/gm in igneous rock and ura11ium l

concentrations of 120 pCi/gm in Florida phosphate rock and 50-80 pCi/gm in Tennessee bituminous shale.

Concentration limits*for natura1 thorium and natura1 uranium ore wastes containing daughters not at secular equilibrium can be ca1cu1ated on a case-by-case basis using the applicable isotopic activities data.

2. Disposal of certain low concentrations of natu.ral thorium with daughters in secular equilibrium and depleted or enriched*uranium with no daughters present when buried under prescribed conditions with no subsequent land use restrictions and no continuing MRC licensing of the material.

Under this option the concentrations of natural thorium and uranium are set sufficiently low so that no member of the public will receive a radiation dose exceeding those discussed under option l when the wastes are buried in an approved manner absent intrusion into the burial grounds. This option.will require establishing prescribed conditions for disposal in the license, such as depth and distribution of materia1, to minimize'the likelihood of intrusion. Burial will be permitted only if it can be demonstrated that the buried materials will be stabilized in place and not be transported away from the site.

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Acceptability of the site for disposa1 will depend on to.pographi ca 1 , geo 1cg ica 1, hydro 1og i ca 1 and ~teoro 1og i ca 1 characteristics of the site. At a minimum, bur~a1 ~:pth wi11 I

be at least four feet below the surface. ln the event that there is an intrusion into the burial ground. no member .of the public will likely receive a dose in excess of 170 mi 11 i.rems to a cri ti ca1 organ.. An average dose not exceed 1ng 170 millirems ta the whole body for all members of a general population is reconmended by .internat,ona1 and nationa1 radiation expert bodies to limit population doses. With respect to limiting doses to individual body organs, the concentrations are sufficiently low that

. , no individual will receive a dose in excess of 170 mi 11 i. rems to any organ*

fran exposure to natural thorium, depleted uranium or enriched uranium.

The average activity concentration of radioactive material that may be buried under this option in the case of natural thori.um (Th ... 232 plus Th-228) is 50 pCi/gm, if a 11 daughters are present~and in equilibrium; for enriched uranium it is 100 pCi/gm if the uranium is soluble and 250 pCi/gm if insoluble; for depleted uranium it is 100 pCf/gm if the uranium fs soluble and 300 pCi/gm if tnsoluble. Natural uranium ores ~ontaining radium 226 and its daugh.ters are not included under this option, because.of possible radon 222 emanations and resultant higher than acceptable exposure of individuals in private residences if houses were built over buried materials.

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3. \ Di sposa 1 of 1ow concentrations of natura 1 ,uranium ores,* with all daughters tn eq~ilibrium, when buried under prescribed conditions 1n areas zoned for industrial use and the l

recorded title documents are amended to state that the

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- specified land contains buried radioactive materials and are conditioned in a manner acceptable under state law to impose:

a covenant running with the land that the specified land may not be used for residential building. (There is no continuing NRC licensing of the material.)

Disposal will be. approved if the burial criteria out1ined in

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option 2 (including burial at a minimum of 4 feet) are met.

Depending upon local soil characteristics, burials at depths greater than 4 feet may be required. In order to assure protection against radon 222 releases (daughter in decay chain of uranium 238 and uranium 234), it is necessary that the recorded title documents be amended to state in the pennanent land records that no residential building should be pennitted over specified areas of land where natural uranium ore residues (U-238 plus U-234) in concentrations exceeding 10 pCi/~m has been buried. Industrial building is acceptable so long as the

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concentration of buried material does not exceed 40 pCi/gm of uranium (i.e., Ra-~26 shall not exceed 20 pCi/gm)w

4. Disposal of 1and-use-1imited,concentrations of natural thorium or natural uranium with daughters in secular equi1ibrium and depleted or enriched uranium without daughters present when

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I buried under prescribed conditions in areas zoned for industrial use and the recorded title documents are amended to state that the land co~tains buried radioactive material and I

are conditioned in a manner acceptable under state law to impose a covenant running wtth land that the 1and (1) may not be exca~ated below stated.depths in specified areas of land unless cleared by appropriate *health authorities .. (2) may not be used for residential or industrial structures over specified areas where radioactive materials in concentrations higher than specified tn opti.ons 2 and 3 are buried .. and (3) may not be used for agricultural purposes in the specified areas.

(There is no conttn~ing NRC licensing* of the disposal site.)

Under this option, conditions of"buria1 will be such that no member of the pub1ic will receive radittion doses in excess of those discussed under option l absent intrusion into the burial, ground. Criteria for disposal under these conditions

' is predicated upon the assumption that intenti.ona1 intrusion is less likely to occur if a warning is given in land documents of record not to excavate below buria1 depths in specified areas of land without clearance by health authorities; not to construct residential Qr indust~ial building on the site; and not to use specified areas of land for agri~u1tura1 purposes.

Because of this, we believe ft appropriate to apply a maximum critical organ exposure 11.mi.t of 500 millfrems per year to thorium

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and uranium buried under this restriction instead of 170 mi11irems as used in options 2 and 3. In addition, any exposure to such materials is likely to be more transient than assumed l -

(essentia11y continual exposure) under those options.* These two

.r factors combine to increase the activity concentration limits calculated under option 2 by about 10. Thus, the average ..

concentration that may be buried under this option for.thorium (Th-2~2 p*lus Th-228} is 500 pCi/gm if a 11 daughters are present and in equilibrium; for enriched uranium.it is 1000 pCi/gm if the uranium is soluble and 2500 pCi/gm if insoluble; and for depleted uranium it is 1600 pCi/gm if the uranium is soluble and 3000 pCi/gm. if insoluble.

With respect to natural uranium with daughters present anq in equilibrium, the concentration that may be buried under this option is 200 pC1/gm of U-238 plus U-234, i.e., *100 pCi/gm

  • ifta-226. This concentration is based on a limited exposure of 2.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> per day to limit the radon dose to less than 0.5 working level month (WLM) which is equivalent to continuous exposure to 0.02 working leve1 (WL). Oepe~ding upon local soil characteristics, burials at depths greater than 4 feet may be required * .

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SUMMARY

OF MAXiIMUM CONCENTRATIONS PERMITTED UNDER DISPOSAL OPTIONS

" ""' *. .1 Oiseosal Options Kind of Material Natural Thorium (Th-232 + Th-228) 10 la

-50zb 3C 4d 500 with daughters present and 1n equilibrium Natural Uranium {U-238 + U-234) 10 40 200 with daughters present and in equil ibri wn Depleted Uranium o Soluble 35 100 1000 o Insoluble 35 300 3000

,;r Enriched Uranium o Soluble 30 100 1000 o I"f'1.soluble 30 250 .. 2500 a Based on EPA cleanup standards.

I b Concentrations based on limiting individual doses to 170 mrem/yr.

  • c Concentration based on limiting equivalent exposure to 0.02 working level or less.

d Concentrations based on limiting individual doses to 500 mrem/yr and, in case of natural uranium, limiting exposure to 0.02 working level or less.

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