Mr. David Friedman

U.S. Environmental Protection Agency, Region Ill

Land & Chemical Division 3LC20

1650 Arch Street

Philadelphia, PA 19103-2029

Ref: Petition to Delisting of Hazardous Wastes (Petition) that was submitted on February 21, 2003

Dear Mr. Friedman:

B&W is providing an update to the referenced petition. B&W has reviewed a early internal

development work report related to the solubility of Calcium Fluoride filter cake and the

technical literature to reference a Calcium Fluoride Solubility Equilibrium Product Constant

(Ksp). A white paper on Calcium Fluoride Solubility is attached.

After you have had an opportunity to review the information, I would like to discuss it with

you and possibly setup a meeting to review the status of the delisting. Should you have

any questions, please give me a call at (434) 522-6677.

Sincerely,

John M. Storton

Senior Advisory Engineer

Babcock & Wilcox Nuclear Operation Group

cc DC Ward RL Coats N Whitten LR Morrell

W H Anderson JT Howard File 3-33473

babcock & wilcox nuclear operations group, inc., a Babcock & Wilcox company
, 

y g

filter cake solids that are

discharged into the ponds are no longer classified by the DEQ as an F006 waste. In 2008

B&W contracted for the removal ofthe sludge in the FEPs and its disposition as a mixed

waste at a licensed disposal site. Nearly all ofthe approximately 13,200 cubic yards of

sludge in the ponds was removed, leaving only about 150 cubic yards. This memo

explains why the relatively insoluble fluoride in the residual sludge does not pose a threat

to groundwater quality.

B&W’ s wastewaters contain spent nitric and hydrofluoric acid. The low-level

radioactive and non-radioactive wastewaters are neutralized in separate treatment

systems. Most ofthe precipitated solids are removed using filter presses and sent todisposal as either a low-level radioactive waste or industrial waste. Only minorconcentrations ofsuspended solids are discharged to the FEPs. B&W’s VPDES permitallows for the discharge of a monthly average fluoride mass of 15 Kg per day with a

maximum of 30 Kg. B&W is in compliance with its VPDES permit conditions.

Currently B&W’s neutralization operation uses a combination of lime (Ca(OH) 2)andsodium hydroxide (NaOH). The sodium hydroxide is used to neutralize the acidity, and

lime is added in a stoichiometric ratio based on the measured fluoride concentration inthe spent acid solution to optimize removal of fluoride via calcium fluoride (CaF 2)

precipitation.

CaF 2is an ionic compound consisting of calcium and fluorine that has a very low

solubility. It occurs naturally as the mineral fluorite (also called fluorspar) and is mined

as a commercial source of fluorine. Fluoride concentrations in water are limited by

precipitation ofthis mineral, which occurs by the reaction:

2F + Ca2 -* CaF 2

At equilibrium, the fluoride concentration is controlled by the solubility constraint:

= [Ca 2] x

where is the fluorite solubility product, equal to 1.64 x 10” at 25° C, and the

variables in brackets are the molar concentrations (moles/liter) of calcium and fluoride.The solubility of fluoride thus varies inversely with the square root ofthe calciumconcentration, which can be expressed as:

[F]= / \! [Ca]

B&W CaF 2 Solubility 1 of 5 7/27/2009
Calcium concentrations in water after contacting the sludge are expected to be well above

20 mg/L because ofthe presence oflime and calcium carbonate, which are solubleminerals that are major components ofthe sludge (discussed below). These compounds

should maintain calcium concentrations well above 20 mg!L, which would prevent

fluoride concentrations from exceeding 4 mg/L. Fluoride present in the sludge is thus not

predicted to impact groundwater because ofthe high soluble calcium content ofthe

sludge.

The B&W solids that are discharged to the FEPs have a complex chemical composition

which is presented in Table 1. B&W collected samples ofthe sludge for analysis to

support development of a waste profile for the material.

The quantity oflime used in the neutralization process has varied historically at B&W,

from lime being the sole chemical used in neutralization prior to 1992, to the current

practice of adding lime in a stoichiometric ratio based on the fluoride concentration. The

composition data presented in Table 1 are based on neutralization before lime wasstoichiometrically added. As a result, there is excess calcium hydroxide in the filter cake

solids.

Table 1 Chemical Composition of FEP Sludge

Chemical Concentration Chemical ConcentrationComponent - Component — Calcium Fluoride - 0-40 % Calcium Carbonate 5 — %

ron Hydroxide - 10-20 % — Calcium Hydroxide - 0-15 % — zirconium 2-20 % -{alogenic Organic

4ydroxide - (HOC) — Compounds (Sum ot \iuminum 10-15 % he list of HOCs.) -lydroxide

In 1979, B&W conducted wastewater treatment pilot plant scale tests for a proposed

commercial nuclear fuel plant. Calcium fluoride filter cake waste is generated from the

B&W CaF 2 Solubility 2 of 5 7/27/2009
The B&W pilot plant tests generated a quantity of CaF 2filter cake that was used for the

long term leach tests. The CaF 2filter cake was dried at 105 °C, ball-milled to pass

through a 16 mesh screen and mixed, then four random samples were collected for

evaluation. The samples were analyzed for specific compounds and the composition data

is provided in Table 2.

Long term leach tests were performed to measure ofthe leach resistance ofthe CaF 2filter

cake. Long-term leach test samples were prepared using polyethylene drying tubes (15.2

cm long with a diameter of 1.6 cm with a Pyrex wool bottom plug). Different mixtures

of soil, soil plus CaF 2filter cake, as well as just CaF 2filter cake were used in the colunm

tests. Each week-day 5 ml of deionized water was added to each tube. The flow rate of

the water through the tube was not controlled. The effluent from the tubes was collected

and periodically sampled. The long-term leach test results are presented in Table 3.

Table 2 CaF 2Filter Cake Analysis Results

Sample No. CaF 2 CaSiO 3 CaCO 3 Ca(OH) 2 KOH

% % % % %

CaF 2-1 46.2 21.0 6.0 13 1.8

CaF 2-2 49.1 11.6 5.8 25.7 2.2

The CaF 2column data in Table 3 indicates only trace concentrations of fluoride is present

in the effluent. These results can be explained by calcium being contributed by the other

slightly soluble calcium compounds in the filter cake (Table 2). The Soil+CaF 2column

data indicates that even less fluoride is present in the effluent when soil is added to the

filter cake. This additional removal process may be ion exchange of F ions with

hydroxyl (OTT) ions present in soil minerals that contain hydroxyl groups. Fluoride ions

will exchange with OW ions that are present as structural components in common soilforming minerals such as clays, amphiboles, micas, and aluminum hydroxides. These

exchange reactions may be contributing to the immobilization of fluoride in the soil.

B&W CaF 2 Solubility 3 of 5 7/27/2009
-I

00E

0

LI

* Last two values not included.

396 0.1 0.8 0.7

427 0.1 0.8 1.5

440 0.1 0.8 1.1

474 0.1 0.6 1.6

517 0.1 0.7 1.4

537 0.1 <0.1 1.1

564 0.1 <0.1 1.3

Mean 0.144 0.700* 1.28

Standard Deviation 0.0882 0.1528* 0.273

Under constant exposure to water for 564 days, only a small portion ofthe filter cake

dissolved and the concentration of fluoride in the effluent remained very low throughout

the test. This implies that fluoride in the CaF 2filter cake has a very low solubility that

limits its concentration in water contacting the material.

These test results, supported by solubility calculations, support the argument that the

fluoride present in the FEP sludge is immobile and will not impact groundwater.

Figure 1. Fluoride Solubility as a Function of Calcium Concentrations

16

14

1210

8

64

2

0

0 50 100 150 200 250 300 350 400

Calcium (mg/I.)

B&W CaF 2 Solubility 4 of 5 7/27/2009
1 .28E-9 grams per liter. The actual concentration of CaF 2in solution is dependent

on a variety of parameters including concentration of Calcium and other ions in

solution.

Calcium Fluoride

Reference

1.64 x 10h1 EQ316 Database

3.98 x 10h1 Penn State Database

1.10 x 10h1 Nordstrom & Jenne, 1977

3.16 x 10h1 Krauskopf, 1967

1.10 x 10h1 MINTEQ Database

2.51 x 10” PHREEQC Database2.63 x i011 Brown & Robertson, 1977

B&W CaF 2 Solubility 5 of 5 7/27/2009