ML20125B301

Responds to Re Decontamination of Wastes,Hazards Posed by Waste Disposal Methods & Classification of High & Low Level Wastes

ML20125B301
Person / Time
Site:	Dresden
Issue date:	10/18/1979
From:	Vollmer R Office of Nuclear Reactor Regulation
To:	Drey L AFFILIATION NOT ASSIGNED
References
NUDOCS 7910300417
Download: ML20125B301 (4)

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! irs. Leo Drey 515 West point Avenue University City, Missouri 63130

Dear Mrs. Drey:

In response to your letter dated July 23, 1979, in which you expressed your concerns related to the decontamination wastes, the following answers are provided for each of your specific questions:

Ql.

Would you please explain to me how it was decided that the estimated 1200 55-gallon drums of the mixture of radioactive corrosion products, chelating solvent, and a vinyl ester resin solidification agent proposed to be shipped and stored subsequent to the Dresden Unit One decontamination experiment would qualify as " low level wastes" rather than "high level"?

Al.

Radioactive wastes are separated into two broad classifications:

"high level wastes" and "other than high-level wastes". Hi gh-level wastes are radioactive wastes produced in the first solvent extraction cycle of fuel reprocessing operations.

If fuel is not reprocessed, the unprocessed fuel will be classified as high-level waste should it be discarded.

High level wastes are highly radioactive, contain significant quantities of transuranic radio-nuclides, and require extensive shielding, sophisticated remote handling techniques, and often require cooling to remove the heat generated by the decay of the contained fission products.

The second waste classification "other than high level wastes" includes wastes that are not produced in the first step of the selvcat ntraction cycle of fuel reprocessing or the untrocessed fuel.

ii.e Dresden 1 unste thet will be produced frv the deccntanination falls into this class and therefore may be buried in a connercial waste burial site.

7910800+/7 L

k "rs. Leo Drey October 18, 1979 02.

Wouldn't the concentrated first cycle decontamination effluent containing irradiated metal oxides, mixed with trapped fission and activation products accumulated over the 19-year operation of the plant -- plus chelating agents designed to sclubilize the crud -- constitute a higher level hazard than, for exanple, discarded HEPA filters, evaporator condensate, workers' clothing or sinilar " low level" wastes irradiated over a much shorter pericd of time and not bonded to chelates?

A2.

The level of hazard associated with the disposal cf ar.y, taste is controlled by the precautions taken in the disposal process to isolate the waste from the tiosphere. A graded rar.ge of safety precautions are applied to waste according to the type and level of radioactivity.

Therefore, liquids are transformed into solids to prc lude leakage during transportation or after burial. Hi ghly radioactive waste shipments are shielded as needed to keep trans-portation exposures below applicable Department of Transportation or NRC limits. At the burial site the level of hazard of highly radioactive waste is controlled by burying it deeper. Therefore, an equivalent level of hazard is achieved by applying additional precautions as necessary.

Q3.

Do you really believe shallow burial in trenches is sufficient to keep the Dresden wastes isolated from the biosphere?

If so, for how long?

A3.

An ERDA study carried out by Drs. Means, Crerar, and Dugried, Science Vol. 200 June 30,1978, was related to the disposal of 35 million gallons of liquid waste which had been' pumped into disposal trenches on the top of a hill.

Subsequent to this liquid waste disposal activity radioactive liquids seeped to the surface at a down hill location.

In the present situation, the Dresden decontamination wastes are being turned into a solid waste form and will be buried in an' arid desert site where the water table is.approxinately 300 feet below the surface.

The absence of liquid in the waste and the large separation frm tFe cround water will assure that the rar n:tivit;. in the vaste will be isolated from the biosphere.

'N Sl'~tino table lists the ecected nuclides md c.antities expected to be present in the Dresden 1 decontamination waste:

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s I'.r." Leo Orey October 18, 1979 NUCLIDE CURIES HALF LIFE Ci/55 Gal. DRuti 60 2160 5.3 years 1.6C Co 1

58 630 22 days 0.53 Co 117 290 days 0.10 144 Ce I44 Pr 54 30 25 days 0.03 Mn 95 Zr 95 fib 21 63 days 0.02 57 15 270 days 0.01 Co 141 15 32 days 0.01 Ce 103 9

41 days

<.01 Ru

<.01 MFP 3

3000 2.50

• The half life of mixed fission products may be approxirated by assuming that T,l_ = t where t is the time since fission.

2 Based on the above, it is seen that after 6 half lives (about 31 years) the only significang0,ctivity remaining will be a

approximately 35 curies of Co an insignificant quantity from a hazards standpoint because the protective shielding of the burial facility was originally adequate for 2160 curies at the time of burial.

Q4.

Would you please tell me how much the crud will weigh which is to be removed from the reactor and piping?

A4.

It is estimated that approximately 450 to 1100 pounds of total deposit will be dissolved and removed during the decontamination.

'; 5.

ich rcdioiretres otMr than cobalt-60 (5.26 year hal#-life) t y:.u eqect to find in the crad; and how many curies of ea:h isotope you expect to be dissolved by the solvent -- bcth the d:rter lived enes which nay only irpact upon the Eealth of the workers participating ia the project, ano the cthers which will pers.ist during shipment and burial?

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' ;rs. Leo. Drey

- 4 October lE,1979

6.

Is it correct that if a drun contains any transuranic wastes totaling nore than 10 nanocuries per gran it will not be allowed to be buried at one of the three remaining connercial icat-level burial sites (that is, in South Carolina, ashincton or Nevada) -- or is this restriction not yet in effect at comercial burial sites?

A6.

The licenses for the Carmtell, South Carolina and Beatty, Nevada sites contain a 10 n Ci/gm limit on transuranic nuclides.

The Hanford site does not have a 10 n Ci/gm limit.

I hope this information is responsive to your request.

Si nce rely, f

! $ i'y [g;->.~. L Richard H. Vollmer, Acting Assistant Director for Systematic Evaluation Program Division of Operatir.g Reactors 0

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