ML20135C740

Submits Listed Requests Seeking Determinations by Dept Pursuant to Section 22a-430-3(d) & 22a-430-4(p) of Regulations of CT State Agencies (Rcsa),Permit Mods Not Necessary to Discharge De Minimus Levels of Hydrazine

ML20135C740
Person / Time
Site:	Millstone
Issue date:	02/20/1997
From:	Scace S NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO.
To:	Grier J CONNECTICUT, STATE OF
References
D10727, SES-97-GN-010, SES-97-GN-10, NUDOCS 9703040251
Download: ML20135C740 (9)

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P.O. Bos 270 Hartford, Cr 06141-0270 (203) 665 5000 February 20,1997 SES-97-GN-010 D10727 Mr. James Grier Supervising Sanitary Engineer .

Water Management Bureau Department of Environmental Protection 79 Elm Street Hartford, CT 06106-5127

Dear Mr. Grier:

i Millstone Station NPDES Permit No. CT 0003263 Request for Determination Following up on recent discussions held with the Department on November 21,1996, January 9,1997 and January 28,1997, NNECO submits the following requests seeking  ;

determinations by the Department pursuant to Sections 22a-430-3(d) and 22a-430-4(p) of the Regulations of Connecticut State Agencies (RCSA) that permit modifications are not ,

necessary to discharge de minimus levels of hydrazine through: 1) DSNs 001B-1 and l l

001C-1; and 2) other discharge points where hydrazine may be present at low parts per billion (ppb) concentrations.

1) Request for Determination: Discharges DSN 001B-1 and DSN 001C-1. Steam }

Generator Blawdown, Millstone Units 2 and 3. l

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In a letter dated July 29,1996 from M. Harder to D. B. Miller, Jr., the Department of g Environmental Protection (DEP) requested additional information regarding permit [OU modification requests submitted by NNECO in May and June of 1996. This information l

was provided by NNECO in a letter dated November 26,1996 from S. Scace to M.

l Harder (Reference 1). For the reasons set forth below, NNECO believes it is unnecessary l to modify the existing NPDES permit to specifically address the discharge of hydrazine for the above referenced discharges.

9703040251 970220 PDR ADOCK 05000245 P PDR e 04001g 1 ,

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i As we have discussed with the Department, Units 2 and 3 attempt to maintain feed rates of hydrazine into the steam generators of up to 50 ppb. After entering the high temperature of the steam generators, and subsequent to recirculation, hydrazine concentrations decline to approximately 10 ppb or less. Upon discharge into the circulating water systems at Units 2 and 3, hydrazine concentrations in DSNs 001B and 001C are further reduced by orders of magnitude. Calculations of these concentrations range from 0.002 ppb to 0.003 ppb for Unit 2, and from 0.001 ppb to 0.002 ppb for Unit 3, depending on the number of service water and circulating water pumps operating while each unit is in operation. These ranges compare very favorably against the Chronic No Observed Effect Level (CNOEL) for hydra'ine which is 20 ppb.

Under DEP regulations, a substance such as hyd azine may be discharged from points that do not contain explicit limits for that substance if the discharge " either results from processes or activities described in the permit application" or the discharge is "in quantities and concentrations which the Commissioner [has] determine [d] cannot reasonably be expected to cause pollution"(RCSA Section 22a-430-3(d)). Millstone's NPDES permit authorizes the discharge of steam generator blowdown from Unit 2 (DSN 001B-1) and Unit 3 (DSN 001C-1). Included in NNECO's submission of November 26, 1996, was historic correspondence identifying the use of hydrazine at low concentrations for corrosion control in steam generators at Units 2 and 3 (Reference 1, Attachment 2).

Thus, the use of hydra 75 asults from processes and activities both described in the permit application and : Meally discussed with the Depanment. Moreover, toxicity evaluations and studies submitted to the Department to date demonstrate that hydrazine does not represent a hazard to the environment at observed discharge levels (Reference 1, Attachment 1). For both these reasons, NNECO believes such discharges are authorized under RCSA Section 22a-430-3(d) without the need for a permit modification.

Alternatively, pursuant to RCS A 22a-430-4(p) (5) (b) (ii) and (vii), the Commissioner may treat as a minor modification requests seeking additional or new monitoring provided that l the new monitoring "does not authorize the discharge of a substance not authorized by the i previous permit" Pursuant to RCS A 22a-430-4 (p) (5) (B) (vii), the Commissioner may l also treat as a minor modification the addition oflimitations on existing pollutants. Here, j since hydrazine results from processes or activities described in Millstone Stations's i Permit or Permit application and does not cause a hazard to the environment, we believe l the Department can address any concerns it may have through a minor modification. l 2, Request for Determination: Measurement and Discharge of De Minimus Ilydrazine Concentrations NNECO is also seeking confirmation that waste waters containing hydrazine in concentrations no greater than 350 ppb and discharged into the circulating water systems at Units 2 and 3, which reduce the hydrazine concentrations by orders of magnitude, cannot reasonably be expected to cause pollution. As part of Reference 1, NNECO appended a recent review of hydrazine aquatic toxicity (Reference 1, Attachment 1) prepared by Nonheast Utilities Environmental Laboratory (NUEL) as well as copies of j 2

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l past aquatic toxicity studies prepared by NUEL. These results have shown no aquatic toxicity in the effluent entering Long Island Sound.

Establishment of a de minimus concentration level for hydrazine would resolve permitting  :

l- issues relative to the detection of hydrazine in amounts below 350 ppb in various l wastestreams prior to discharge into the quarry at Millstone Station. Given the extremely  !

low de minimus level and the attendant mixing with circulating water, NNECO beheves <

that resulting concentrations will be well below the CNOEL for hydrazine.

As set forth in our submittal of February 10,1997 (Reference 2), NNECO has performed ,

a detailed evaluation of the applicability of the spectrophotometric analytical method to I measure hydrazine in effluent sources. These results are summarized in Attachment 1. In I short, we found that for most discharge paths, including those above, there would be considerable interference by total suspended solids (TSS) and color when using spectrophotometry to measure the concentrations of hydrazine in NNECO's wastewaters.

Results demonstrate that the spectrophotometric method gives false positives for hydrazine. Accordingly, we have concluded that the titration method is the appropriate method to use where TSS interference is likely. Use of the titration method would detect hydrazine down to the proposed de minimus concentration.

l Should you have any questions, please call Mr. Paul Jacobson, Environmental Services -

! Nuclear at (860' ' '. /-1791, Ext. 2335.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY l

l 1l V /C S. Scace '

! Director - Nuclear Engineering Programs l

l cc: M. Harder NRC I

REFERENCES:

1) Letter SES-96-GN-047 from S. Scace to M. Harder, dated November 26,1996.

. 2) Letter D10802 from S. Scace to J. Grier dated February 10,1997.

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l Attachment 1 Evaluation of Spectrophotometric Analysis for Hydrazine This report summarizes results of an evaluation of the UVNIS spectrophotometric analysis method for hydrazine. Specifically, this report explores how this analysis performs under chemical matrix conditions expected in a typical waste neutralization sump or waste drain tank.

NNECO sought to determine which method to employ in streams where hydrazine may be present only at ppb levels. In this study, samples of both the waste neutralization sump and waste drain tanks were used in the laboratory evaluation.

Waste Neutralization Sumo A sample was taken from the Unit 2 waste neutralization sump TK-10 (which discharges to DSN 0018-6) following an appropriate recirculation period. The water in this sump was present as a result of draining evolutions associated with lay-up of the resins. While, this particular batch of water is not expected to contain hydrazine, the chemical matrix of the wastewater is representativa of that which will be present during p:3nt operation (high total dissolved solids and corrosion products).

The sample was initially analyzed by iodine titration and t Sund to contain less than the minimum detectable level of 350 ppb hydrazine. Spectrophotometric analysis of this same sample then yielded a result of 271 ppb hydrazine. The sample was then processed through a series of glass fiber filters, each with a diminishing particle size, and the collected filtrate was analyzed for turbidity as well as hydrazine. The results are listed in Table 1 and show a clear correlation between the amount of suspended matter in solution and the measured concentration of hydrazine.

Table 1 TK-10 Analysis Sample Hydrazine Concentration Turbidity (NTU)

(ppb)

Raw 271 22.5 10 rnicron effluent 154 15 8 micron effluent 139 13 5 micron effluent 122 11 0.8 micron effluent 92 10 0.45 micron effluent 1 81 7.5 The relationship between turbidity erd hydrazine in the TK-10 sample is graphically illustrated in Chart 1. Linear regression analysis was employed to construct a best fit curve of the laboratory data. The equation and correlation coefficient of the curve are included with the chart. The curve was then extrapolated down to 2.8 ppb to determine the minimum turbidity level necessary to generate a hydrazine concentration equal to the limit of detection (LOD) of the spectrophotometric method. Based on that analysis, turbidity is equal to approximately 2.5 nephelometric turbidity units (NTUs).

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. I i l l l l Chart 1 l TK-10. Turbidity vs Hydrazine Concentration Turbidity vs Hydsz!ne i 30

^* j 26 - y = 0.0768a + 2.3171 R' = 0.9708 l 16 -

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O 80 100 150 200 260 300 Hydrazine Concentration (ppb)

I i l' Another sample of TK-10 was collected and processed in a similar fashion to further test the consistency of this effect. Aliquots of the filtrate were also spiked with a known quantity of hydrazine and the percent recovery was calculated. These results are listed in Table 2.

Table 2 TK-10 Analysis with Spike Recovery Sample Hydrazine Turbidity (NTU) Hydrazine Percent Concentration Concentration after Recovery ;

(ppb) 35 ppb spike (ppb) (%) l Raw 273 22.5 304 88.6  !

10 micron effluent 153 15 183 85.7 8 micron effluent 128 13 160 91.4 0.8 micron effluent 88 10 129 117 0.45 micron effluent 86 7.5 108 62.9 i

The results listed in Table 2 indicate the spectrophotometer is capable of disceming relatively l l small changes in hydrazine concentration (as witnessed by the percent recovery values), yet it i j is quite susceptible to interference from matter suspended within the solution. l l

In an effort to gather more information, a sample of TK-11 was drawn and submitted to the 1 same filtration and analysis techniques. The water in TK-11 is from the same source as that of TK-10. Even so, it was noted that the color of the suspended matter in the TK-11 sample was decidedly different from that seen in the TK-10 sample. In contrast to the dark black of the TK-10 material, the solid matter in the TK-11 sample was light brown. This may be due to a difference in the oxidation state of the corrosion products (which make up the bulk of the filterable solids), although there is no analytical data to support this hypothesis. The results from the TK-11 analyses are presented in Table 3.  ;

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l Table 3 TK-11 Analysis with Spike Recovery Sample Hydrazine Turbidity (NTU) Hydrazine Percent Concentration Concentration Recovery (ppb) after 35 ppb (%)

spike (ppb)  :

Raw 203 25 193 -28.6 10 micron effluent 44 15 60 45.7

, 8 m:cron effluent 41 13 58 48.6 0.8 micron effluent 35 10 54 54.3 0.45 micron effluent 29 8 49 57.1 The effects from the suspended matter on the measured hydrazine concentration in the TK-11 sample were greater than those encountered in the TK-10 sample. This is clearly evident in the linear regression curve constructed for the TK-11 data (Chart 2). The most likely reason is the difference in color between the two samples. It would appear that interference of the spectrophotometric analysis is a function not only of the amount of suspended matter but also the oxidation state, making hydrazine quantification all the more difficult. Filtration will reduce the turbidity, but will be ineffective on color related interference.

Chart 2 TK-11, Turbidity vs Hydrazine Concentration Turbidity vs Hydrazine 36 y = 0.0837a + B.3047 30 - R' = 0.887

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0 60 100 160 200 260 300 Hydrazine Concentration (ppb)

The extent of analytical interference was further pursued by performing a spectrographic scan

of the TK-10 & 11 raw samples. The " scan" function of the Perkin Elmer Lambda 2 Spect ophotometer provides a measurement of absorbance versus wavelength for a given sample. At the 458 nm wavelength used for hydrazine analysis, TK-10 exhibited 0.75 absorbance units while TK-11 exhibited 0.90 absorbance units. Both samples had a similar 3

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mass of suspended matter. As a reference, a 100 ppb concentration of hydrazine in a pure water matrix will exhibit 0.128 absorbance units.

I The manufacturer of the instrument was contacted to obtain further insight. Perkin Elmer '

provided a curve of absorbance versus wavelength derived from a turbidity method developed for the Lambda 2. The curve clearly shows that the highest absorbance occurs in the ,

wavelength range of 360 to 600 nm. Since the hydrazine absorbance is measured at 458 nm, j this infers that even modest levels of turbidity will produce a false positive indication of l hydrazine.The Perkin Elmer representative reiterated that low level hydrazine analysis should only be performed on samples with a pure water matrix. According to Perkin-Elmer, samples  ;

with a turbidity of 1 NTU or greater will produce inaccurate results for hydrazine. As demonstrated above, sequential filtration down to 0.45 microns was unsuccessful at producing an acceptable turbidity in the waste neutralization sump samples. j An attempt was then made to compensate for turbidity effects by using an untreated (no reagents added) cuvette of the waste neutralization sump water as a blank. The blank solution '

had the Em3 product mass and oxidation state as that of the solution being analyzed for hydrazine Repeated trials produced the same result: an error message. Once again, Perkin Elmer uttributed this to the turbidity level of the solutions.

A final attempt to remove the turbidity consisted of sample treatment with anion exchange resin. Another sample of TK-10 was collected and sequentially processed through glass fiber filters of diminishing pore size, culminating at 0.22 microns. This served to reduce the turbidity from 25 NTU's to 3.5 NTU's. The collected filtrate was then passed through a column containing Dowex* monosphere anion resin. If the suspended matter causing the remnant turbidity existed as a negatively charged species, the anion resin would functior, ally remove it without affecting any hydrazine that may be present.

The anion resin effluent was then analyzed for turbidity, with the results showing 3.5 NTU's; no change. An aliquot of the anion effluent was then prepared for spectrophotometric analysis, along with a 35 ppb hydrazine controlled standard, prepared in a pure water matrix. After waiting the appropriate amount of time for color development, the control standard exhibited the familiar yellow hue seen in hydrazine bearing samples. No color change was observed in the anion resin effluent semple. Subsequent analysis in the spectrophotometer produced a result of 34 ppb for the control standard and 28 ppb for TK-10.

! Therefore, the fact that a sample with no visible color development can produce a measured result close in concentration to one with a known quantity of hydrazine further confirms the turbidity-related interference and illustrates the difficulty in obtaining an accurate hydrazine value with the spectrophotometric method on waste streams containing measurable turbidity.

l Significantly, the presence of suspended solids in solution had little, if any, effect on the iodine l titration method of analysis. Samples from TK-10 & 11, utilized with the spectrophotometric

! experiment, were spiked with known quantities of hydrazine and analyzed by iodine titration.

The results are presented in Table 4.

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Table 4 TK-10 & 11 Spike Recovery with lodine Titration ,

i Sample TK-10 Percent TK-11 Percent  :

Description Recovery (%) Recovery (%) )

Raw < 0.35 ppm N/A < 0.35 ppm N/A l l 10 ppm Spike 11 ppm 110 12 ppm 120 25 ppm Spike 26 ppm 104 27 ppm 108 l 50 ppm Spike 54 ppm 108 51 ppm 102 )

100 ppm Spike 97 ppm 97 103 ppm 103 l

l Waste Drain Tank ,

h A testing regimen similar to that employed with the waste neutralization sump samples was  ;

used with the aerated waste drain tank water which discharges via DSN 0018-2. A sample i from the "A" aerated waste drain tank was analyzed for hydrazine using the iodine titration l method and found to contain less than the minimum quantifiable level cf 350 ppb. i Spectrophotometric analysis of this same sample yielded a result of 42 ppb hydrazine. The ,

sample was then processed through a series of filters and analyzed. Spike recovery testing was also performed. Turbidity analyses were unable to be performed due to a malfunction of the instrument. A summary of the results can be found in Table 5.

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Table 5 "A" Aerated Waste Drain Tank  !

l Sample Hydrazine Hydrazine Percent Recovery Concentration (ppb) Concentration after (%)

30 ppb spike (ppb)

I Raw 42 53 36.7 10 micron effluert 12 25 43.3 0.8 micron efflug ' 9 22 43.3 0.45 micron effluent 8 22 46.7 l The pattern of cecreasing hydrazine for decreasing suspended mass was noted along with the l- poor percent of recovery. It was also noted that the color of the suspended matter in the aerated waste drain tank sample was similar to that observed in the TK-11 sample. Thus, it appears that turbidity and sample color effects are not confined to the waste neutralization sumps alone.

Summary l l I

Based on the above investigations, hydrazine analysis by UVNIS spectrophotometry is highly dependent on the quantity, as well as color, of undissolved matter in the sample being analyzed. Sequentital filtration is not a suitable remedy as repeated attempts in the laboratory ,

were unsuccessful at reducing the turbidity to a point where interference was less than the l LOD of the analysis. Furthermore, filtration will not affect sample color. The use of spectrophotometry for hydrazine analysis should be restricted to samples without a l measurable total suspended solids (TSS). This effectively eliminates analysis of the l 5

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condensate polishing waste neutralization sumps by this methodology and, unless the criteria of turbidity and color are reached by some processing regimen, the aerated waste drain tanks i as well. As a result, the most appropriate and accurate analytical method for these streams is  !

iodine titration.

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