ML19323G178

Steam Generator Chemistry Study

ML19323G178
Person / Time
Site:	Prairie Island
Issue date:	02/29/1980
From:	NWT CORP.
To:
Shared Package
ML19323G170	List: ML19323G175 ML19323G177 ML19323G178
References
TAC-12657, NUDOCS 8005300507
Download: ML19323G178 (17)

Text

e Attachment C Docket No. 50-306

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PRAIRIE ISLAND - UNIT 2 LER R0-80-03 5/23/80 CHEMISTRY CAMPAIGN, FEBRUARY 1980 FIRST PERIOD, 6 - 8th FEBRUARY Samples were collected from the Prairie Island Unit 2 Steam Generators during reactor heat-up from 180 F to 490'F.

The heatup was interrupted at 1730 on 8th February, and the chemistry sampling program discontinued. The results of analyses carried out on site by Westinghouse personnel are shown in Table 1.

Table 2 shows complementary analyses carried out by Westinghouse on samples collected during the same time period.

The data contained in these two tables may be examined on the basis of one data source, and has been evaluated in this manner.

The majority of the samples obtained during this two day period were taken when the steam generator blowdown lines were isolated, and must, therefore, be re-garded as being not totally representative of the bulk liquid within the SGs.

Because of this constraint, it is probable that only those samples collected at 0915 on 8th February will reflect the environment within these SGs at that time.

A second, but 'more questionable, data point exists at 1315 on the same day -

but at the time of sampling blowdown had been restarted only some five to ten minutes, after having been isolated for just over two hours.

This observation suggests that the analytical results may be used as a basis for qualitative examination, but cannot withstand quantitative evaluation.

Table 3 takes data from Tables 1 and 2 and is used to calculate Calcium to Sulphate Molar Ratios (MR) and the apparent cation conductivity deficit, based upon the sulphate ion content, for the listed samples.

In the latter case, no allowance is made for the chloride ion content of these samples, since in most cases the chloride concentration is reported as <0.05 ppm.

(0.05 ppm chloride corresponds to a cation conductivity of 0.6 uu/cm at 25*C.)

80053005b44

The analyses listed in Table 2 indicate the dissolution of significant quantities of nornally soluble ionic species which had partitioned in the steam generator during power operation s a result of hide-out, dry-out, or some similar ' thermal or thermal gradient.incoced concentration mechanism.

The major cations returned to solution are sodium, calcium, and magnesium. Sulphate and silicate are the major anions.

From the available data it is not possible to make definitive comment upon the source of the sulphate ions.

However, the samples collected in the time period 0915 to 1315 on 8th February clearly indicate the presence of a non-stoichiometric calcium to sulphate ratio in the SG bulk liquid. This is not the case for the samples collected on 6th February when MR Ca/SO4=1. The relatively high concentrations and molar ratios of calcium and sulphate ions present in the samples may indicate the existence of a continuous low level source of soluble sulphate ions to the feedwater, and the sequestration of calcium ions within the steam generators.

Based upon the available information this is more probable than the direct precipitation of calcium sulphate on the SG heat transfer surfaces.

At this time it is not possible to comment upon the apparent cation conductivity deficit observed in these samples.

Further efforts should be made to investigate this during some fu'ture reactor shutdown at the Prairie Island plant.

It is, however, of interest to note, that although SG 21 shows a relatively larger hide-out return, the apparent cation conductivity deficit is significantly greater in SG 22 than in SG 21.

This observatinn is summarized in Figure 1 which plots sulphate ion con-centration against cation conductivity in the two steam generators.

~

l

.,e SECOND PERIOD,12 - 13th FEBRUARY Blowdown samples were collected from the steam generators of both power plants and the Unit 1 condensate storage tank by NSP personnel for analysis by Westinghouse at Forest Hills.

The data displayed in Table 4..s found to be inconsistent, and indicative of sample contamination.

Examination of the containers used to transport the water samples showed the presence of a partially destroyed seal in the cap of several of the bottles.

It is possible that soluble species present in the cap seals had, to some variable extent, dissolved in the water in each of the bottles and could account for the anoaalous results obtained in the laboratory.

For the purposes of plant evaluation these results have not been included.

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THIRD PERIOD,18th FEBRUARY A water sample collected from Unit 1 Condensate Storage Tank,which was being used to supply water to Unit 2 steam generators during the first sample collection period (see Table 2),was reported as containing 700 ppb sodium. Wl.ile this is possible, it was not probable, based upon comparison with the SG data collected at the same time.

In order to confirm the validity of this supposition, replicate samples from selected water sources at Prairie Island were collected by NSP personnel and shipped to Westinghouse for analysis.

Table 5 shows the results obtained in the Forest Hills Laboratories.

The " Blank" sample and the "Demin Train Exit" (DTE) are, in effect, water from the same source but sampled in different locations.

It appears that two of the-three DTE samples became contaminated at some stage.

The reported high sodium ion concentrations were confirmed by repeat analyses, and must be assumed to be real for tbc samples received at Forest Hills, but non-representative of the water being p.,duced by the water treatment plant at the time of sampling.

Analyses were also run to check the possible presence of organic phosphate com-pounds in the raw water supply.

The analytical results obtained indicate that if any such compounds are present, they are being effectively removed by the water treatment make-up plant.

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e

FOURTH PERIOD,19 - 21st FEBRUARY In order to collect data during powar escalation, and to amplify the information on the chemical behavior of the Prairie Island 2 secondary side during plant start-up, a further set of samples were collected by NSP chemistry personnel and analyzed by Westinghouse at Forest Hills.

The results of these analyses are shown in Table 6.

The samples were collected at Hot Standby, low Power Operation (10%), Transfer to bbin Feed Pump Operation (25%), and nominal Power Operation (48%).

Bias in the analyses is indicated by the concentrations of the cations and anions found in the blank. The results reported for the various samples have not been corrected for blank.

It is pertinent to note the effect of make-up water dilution on the quality of water in the SGs at the start of this survey (0545 on 19th), as compared with the situation evidenced by the data displayed in Table 2.

The samples collected at 1730 on 19th February show the wash-out of significant quantities of soluble ionic species from the steam circuit, most probably the reheater section of the Moisture Separator Reheaters.

There is also evidence of this same wash-out effect in the condensate, but to a much lesser extent.

,,t trjs time there is no obvious change in the quality of water in the steam generators, which remain isolated from the pumped forward reheater drain circui t.

The 2000 hr. samples indicate that the steam circuit has essentially been washed

' clean. The more soluble species are present at much lower concentrations and l

condensate / feed quality has improved when compared with the results recorded for the samples collected at 1730 hrs.

Water quality in the steam generators, however,' has decreased, due to incomplete removal of the impurities carried forward to the SGs by the incoming feedwater from the condensate and the cascaded LP_ drains.

9 w

The data shown for the samples collected on 21st February show the clean-up of SG bulk water chemistry which may be attributed to hide-out during powr.r aperation.

Although the power level is low (48%), the effectiveness of hide-out as an in-voluntary method of removing impurities from the bulk water can be seen in these analyses.

Species such as sodium, potassium, silicate, and sulphate appear to follow a similar decreasing trend.

Calcium, and possibly magnesium, however, show an atypical behavior.

It was considered prudent to disregard these latter analyses in evaluating this set of results.

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• mm.

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CONCLUSIONS AND RECOMMENDATIONS 1.

There is evidence of significant hideout during power operation of the Prairie Island Unit 2 Steam Generators.

From the data obtained during the surveys described in this report sulphate, silicate, and calcium appear to be the species most susceptible to hide-out.

2.

Maximum steam generator blowdown should be employed during plant heat-up to optimize the removal of chemical species from the steam generators which tend to hide-out.

Not doing so at this time may result in a significant hide-out in the early stages of power operation.

3.

The data collected during this survey indicates that a significant quantity of soluble chemicals are washed from the MSRs when steam is first admitted to the turbine / reheat circuit.

This initial highly contaminated condensate should be routinely overboarded, or cascaded back to the condensers for clean-up by the condensate polishing system whenever the unit is returned to power operation.

4.

There is evidence of feedwater contamination by sulphate.

The source of this contimination should be identified, and - if possible - removed.

If removal or elimination is not possible, steps should be taken to reduce the rate of contaminant ingress, i

5.

Steam generator shutdown chemistry indicates the existence of calcium ingress.

This could be as slip from the water treatment plant demineralization system

~

or some undefined raw / cooling water source which interfaces with the secondary i

circuit.

Attempts should be made to identify and, as far as possible, eliminate this source of contamination.

i J

TABLE 1 PRAIRIE ISLANO UNIT 2 ON SITE A!!ALYTICAL RESULTS N02 4 - ppm C1 - ppm Blowdown T

SG Water Cat. Cond.

pH NH3 - PPA av umho/cm GPM Level - %

ATE TIME SG 21 SG 22 SG 21 SG 22 SG 21 SG 22 SG 21 SG 22 SG 21 SG 22 SG 21 SG 22

• F SG 21 SG 22 0

0 180 5/80 0830 6.0 3.8

• 1020 6.0 3.8 9.1 9.1 0.51 0.66 22.5 31.5

<0.05

<0.05 0

0 180 0

0 180 7/80 0950 6.4 4.4

~8/80 *0005 6.5 4.8 8.8 9.0 0.53 0.77 14.0 26.0

<0.05

<0.05 0

0 200 36 91

• 0212 6.6 4.8 8.9 9.0 0.48 0.69 12.5 30.0

<0.05

<0.05 0

0 240 36 91

<0.05

<0.05 0

28 292 70 78 0540 6.5 4.7

<0.05

<0.05 11 28 340 40 43

• 0800 6.4 4.8 9.2 9.5 0.74 1.13 24 26 340 40 44

• 0915 8.3 6.0 9.5 9.8 1.33 2.68 8.8 16.0 0.07 0.06 0

0 400

• 1250

• 1320 7.8 5.5 9.4 9.5 1.28 2.68 8.5 15.0 0.06

<0.05 20 20 400 40 40 0

0 450 1505 7.8 5.8 0

0 475 1600 1730 HEATU ) SECURI O O

O 490 0

0 4.2 3.3 1815 0

0 455

~ 27 38

• 2000 7.0 5.8 i

• SAMPLES RETURNE0 TO FOREST HILLS FOR ADDITIONAL ANALYSES I

TABLE 2 PRAIRIE ISLAND UNIT 2 SAMPLES ANALYZE 0 AT FOREST llILLS - PPB T

DATE TIME S/G av 110 4 dor t 504 SiO2 Na K

Li Ca Mg Cu op 9

• 2/6/80 1020 21 180 0

620 80 14

<10

<1 235 14

<3 22 180 0

240 90 10

<10

<1 100 3

<3 2355 21 200 0

620 140 14

<10

<1 310 16

<3 22 200 0

270 150 12 10

<1 155' 5

<3 2/8/80 0207 21 240 0

620 200 390 10

<1 310 15

<3 22 24 0 0

280 180 200 10

<l 155 5

<3 0755 21 340 11 630 250 86

<10

<1 335 14

<3 22 340 28 270 280 3600 15

<1 220 4

25 0915 21 340 24 720 920 500 30

<1 650 92

<3 22 340 26 320 590 72 20

<1 375 32 12 1250 21 400 0

690 1400 580 50

<1 625 61

<3 22 400 0

320 910 48 35

<l 360 23 3

1315 21 400 2C

-650 1390 88 50

<1 610 58

<3 22 400 20 300 890 42 30

<1 335 22 10 1955 21 450 0

630 2290 260 75

<1 520 32

<3 22 450 0

260 1500 410 50

<1 335 18

<3

j COND. STORAGE TANK 50 20 700

<10

<l

<10 2

<3 m

TABLE 3 PRAIRIE ISLAND UNIT 2 DATE Tit 1E Ca

• SO MR H+A H + A*

AH+A 4

2/6/80 1020 235 620 0.91 6.0 5.55 0.45 2/7/80 2355 310 620 1.20 6.5 5.55 0.95 2/8/80 0207 310 620 1.20-6.6 5.55 1.05 0755 3 35 630 1.28 6.4 5.64 0.76 SG 21 0915 650 720 2.17 8.3 6.45 1.85 1250 625 690 2.17 6.18 1315 61 0 650 2.25 7.8 5.82 1.98 1955 520 630 1.98 7.0 5.64 1.36 MEAN 6.94 5.80 1.20 2/6/80

.020 100 240 1.00 3.8 2.15 1.65 2/7/80 2355 155 270 1.38 4.8 2.42 2.38 2/8/80 0207 155 280 1.33 4.8 2.51 2.29 0755 220 270 1.96 4.8 2.42 2.38 30 0915 375 320 2.81 6.0 2.87 3.13 1250 360 320 2.70 2.87 1315 335 300 2.68 5.5 2.69 2.81 1955 335 260 3.09 5.8 2.33 2.47 MEAN 5.07 2.53 2.44 2-t MW S0,4 ppm 4

HS04 AS0

1. 3g H+A*

=

l

" HSO -

EWSO 2-4 4

FIGURE 1 SG 21 SG 22 - e 800 -

700-600-504 400-l 300-e e

200-l' 100-1 2

3 4

5 6

7 8

9 10

~

~

Cat. Cond.

4 SG SULPHATE CONCENTRATION VS. CATION CON 00CTIVITY PRAIRIE ISLAND 2, FEBRUARY 1980

TABLE 4 PRAIRIE ISLAND UtlIT 2

(!4SP)

ACID PRESERVED - A. A. DETERMItiATION T10t1 PRESERVED SAMPLE DATE tit 1E S/G 3D RATE K ppb Ca ppb Mg ppb Cu ppb Li ppb tiA ppm SO4 Cl ppo S10pppm Ogcm 2/12/8C 1105 11

<6

<10

<10 2

<5

<1 3.10 0.01 0.05 0.03 0.04 1115 12 27 16 4

3.25

<0.01 0.03 0.04 0.06 2/12/80 1130 21 14 54 9

2.03 0.04 0.02 0.56

' O.05 1130 22 14 40 6

0.145 0.02 0.05 0.43 0.07 2/12/80 1900 11 27

<10 9

0.192

<0.01 0.02 0.03 0.03 1900 12 27 13 9

0.585

<0.01

<0.01 0.05 0.03 2/12/80 2115 21 CST 42 10 0.195 0.02 0.01

<0.01 0.05 2/13/80 0300 11 27 11 4

0.154 0.09 0.02 0.05 0.01 0300 12 25 V

24 4

V V

0.117

<0.01 0.01 0.04 0.07

+

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TABLE 5 PRAIRIE ISLAND UNIT 2 (NSP)

ACID PRESERVED - A. A. DETERMINATION NON PRESERVED SAMPLE 2 pm P0 ID DATE TIf1E K ppb Ca ppb Mg ppb Li ppb Na ppb SO ppm Cl ppm SiO P

4 1A 2/18/80 0910

<10

<10

<S

<1

<5

<0.01

<0.01

<0.01

<0.01

<0.01

<0.01 Blank 18 2/18/80 0910

<10

<10

<5

<1

<5 1C 2/18/80 0910

<10

<10

<5

<1

<5

<0.01

<0.01 Condensate 2A 2/18/80 1000

<10

<10

<5

<1

<5

<0.01

<0.01

<0.01

<0.01 Storage 2B 2/18/80 1000

<10

<10

<5

<1

<5

<0.01

<0.01 Tank 2C 2/10/80 1000

<10

<10

<5

<1

<5

<0.01

<0.01 Demin 3A 2/18/80 1020

<10

<10

<5

<1 30 0.04

<0.01

< 0. 01

<0.01

< 0. 01

<0.01 Train 3B 2/18/80 1020

<10

<10

<5

<1 35 Exit 3C 2/18/80 1020

<10

<10

<5

<1

<5 0.06 0.02

< 0. 01

< 0. 01 Raw 4A 2/18/80 1030 2.3 ppra 81.0ppo 28.0 ppm

<1

12. 5ppni 32.5 15.0 21.5 0.04 Wel'1 4B 2/18/80 1030 3.0 ppm 81. 0ppn28.0 ppm

<1 12.9ppn 32.5 15.0 22.C, 0.05

,1 12.4 ppn 32.5 15.0 21.0 0.07 Water 4C 2/18/80 1030 2.55 ppm 81.0ppc 28.0 ppm i

}t

• SAMPLE SUSPECTED TO BE CONTAMINATED O

TABLE 6 PRAIRIE ISLAND UNIT 2 - POWER ESCALATION Cations expressed in opb (unless indicated as ppm), Anions expressed in oom TIME DATE K

Ca ilg Cu fla 5 04 Cl SiO2

% Power i

Condensate 0645 2/19/80 4

95 11 13 110 0.06 1

1 SG 21 0545 1

135 42

<5 68 0.16 0.14 0.31 SG 22 0545 1

130 27

<5 70 0.01 0.06 0.26 Condensate 1730 2/19/80 4

1 51 23 24 120 0.12 0.04 0.04 10 l

Feed 2

71 10 12 52 0.04 0.04 0.03

}

SG 21 10 163 25 16 170 0.18 0.15 0.96

!l SG 22 4

81 12 24 94 0.13 0.10 0.49 MSR 1.66ppml.393pp: 1 95 45 8.2 ppm 1.60 0.49 1.79 Condensate 2000 2/19/80 2

123 17 10 90 0.08 0.02 25 i

Feed 2

68 6

<5 48 0.02 SG 21 1945 20 192 20 57 240 0.22 0.13 0.78 SG 22 1945 25 230 26 44 280 0.58 0.19 1.35 MSR 3

316 29 13 74

<0.01 0.02 0.19 Condensate 0615 2/21/80

<l 55 5

<5 30

< 0. 01 0.02 0.01 48 Feed 1

84 8

<5 68 f

SG 21 0600 4

337 29 74 108 0.12 0.07 0.50 l

SG 22 0600 3

355 28 89 104 0.08 0.06 0.36 L

)

MSR

<1 79 9

15 28

<0.01 0.05 0.04 Blank 2/20/80

<1 51 5

<5 30 0.05 0.02 0.01

O PRAIRIE ISLAND UNIT 2 STEAM GENERATOR CllEMISTRY STUDY FEBRUARY 1980 O

I PERFORMED BY:

NWT, INC.

7015 Realm Drive San Jose, California 95119 i

i

O O

O UNIT 2 HEATUP (VALUES IN PPB)

Page 1 DATE TIME TIMP SAMPLE Na Ca Mg SO4 SiO9 PO4 C1

___ Blow Down 2/7 2350 200*F 21 S/G 220 5.1 270 150 20 67 0

22 S/G 31 440 23 410 110 8

25 0

2/8 0200 240*F 21 S/G 7.2 340 19 24 170 17 35 0

22 S/G 26 210 10 282 170 15 27 0

2/8-0300 21 S/G 17 320 14 707 230 7

30 0

2/8 0800 340*F 22 S/G 28 220 7.2 24 280 6

27 28 2/8 0900-340*F 21 S/G 80 560 98 120 970 4

77 24 22 S/G 46 350' 37 400 620 7

54 26 2/8 1245 400*F 21 S/G 93 430 65 760 1510 3

88 0

22 S/G 62 270 26 68 920 7

56 0

.2/8 1315 400*F 21 S/G 85 430 63 870 1340 4

77 20 22 S/G 54 290 24 330 890 7

46 20 2/8-1515

.450*F 11 CST 33 5.7 11.7 28 5

N.D.

N/A 21 S/G 100 370 46 910 1870 4

92 0

22 S/G 64 220 22 340 1230 6

50 0

UNIT COOLED DOWN

~

2/9 1000 140*F 21 S/G 97 340 100 600 1670 12 72 0

22 S/G

'58 160 48 300 1100 17 44 0

2/9 2330 200*F 21 S/G 92 280 94 620 1720 13 100 0

22 S/G 58 270 58 25 1085 18 53 0

2/10 0130 240*F 21 S/G 97 280 92 11.8 1650 9

83 0

22 S/G 64 250 49 330 1140 11 47 0

2/10 0240 285'F 21 S/G 99 360 71 520 1960 10 78 20 22 S/G 64 210 40 23 1240 12 57 20

O O

O UUNIT 2 REATUP (CONT.), (VALUES IN PPB)

Page 2 DATE TIME TEMP SAMPLE Na Ca Mg Son S107 P0a Cl Blow Down 2/10 0800 285'F 21 S/G 40 240 40 530 940 8

45 15 22 S/G 87 250 77 320 1490 7

58 13 2/10 1000 11 CST 1.4 1.4 13.4 20 2

N.D.

N/A 2/10-1335 335'F 21 S/G 68 250 61 370 1190 7

50 32 22 S/G 35 220 36 156 300 11 38 18 2/10 1620 400*F 21 S/G 45 270 42 250 1050 4

47 41 22 S/G 38 130 18 120 850 7

31 25 2/10 1910 450*F 21 S/G 38 240 30 320 970 4

37 43 22 S/G 40 160 16 9.5 740 4

37 22 UNIT 2 POWER ESCALATION 2/19 -

0545 1%

CN 40 15 4

90 39 18 23 N/A 21 S/G 20 98 41 15 320 2

14 0

22 S/G 33 84 25 7.1 280 22 16 0

2/19 1730 10%

CN 25 23 4.8 37 34 30 7

N/A FD 40 11 5

35 80 15 11 N/A 21A MSR 7800 1000 100 380 2280 68

>100 N/A 21 S/G 94 102 18 80 430 54 58 15 22 S/G 104 85 12 120 1060 14 38 15 2/19 1945 25%

CN 34 73 6

8.7 26 11 4

N/A FD 6.8 1.6 0.38 9.9 74 11 7

N/A 21A MSR 54 228 20 4.3 217 25

-10 N/A 21 S/G 180 166 18 330 345 18 65 16 22 S/G 205 206 26 350 1480 12 74 32 2/21 0600 48%

CN 3.6 3.2

<.05 3.7 5

1.8 3

N/A FD 4

2 0.37-1.7 24 2

N.D.

N/A 21 S/G 75

.267 26 68 520 5

67 35 22 S/G 55 240 25 53 320 9

32 40 4