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COOLANT CHEMISTRY IN NUCLEAR POWER PLANTS IN THE REPUBLIC OF KOREA

NATIONAL CONTRIBUTIONS

COOLANT CHEMISTRY IN NUCLEAR POWER PLANTS IN THE REPUBLIC OF KOREA

Jae-Choon YANG

Chungnam National University, Taejon, Republic of Korea Abstract

The primary coolant radioactivity control of the operating power reactor core is an essential counter-measure for radiation esposure reduction.

We have presented the crud analysis results of the spent fuel rod cladding surface, analysis results of the defected fuel element and the amount of tramp uranium, and the analysis

results of sipping tests.

As we have compared the our analyses results with the coolant histories of the end of cycles, we can see that the amount of crud materials and the number of defected fuel elements are closely related to the reactor water control.

1. Introduction

The reliability of many system materials at nuclear power plants depends on primary coolant control.

The reliability and safety are achieved by using proper cladding and structure materials and special measures are taken to prevent dangerous corrosion products, fission products release and other processes.

The primary coolant radioactivity control is an essential countermeasure for radiation exposure reduction.

We have measured the radioactivity of primary coolant to analyze the radiation source.

The crud samples have been taken from the spent fuel rod cladding surface of Korea Nuclear Unit 1 and analyzed the radioactivities of isotopes.

The measurement and analysis of fission products in the primary coolant of nuclear power reactor have been carried

out at full power operating condition of pressurized water reactor We have analyzed the defective fuel element and tramp uranium

We have analyzed the sipping test results of spent fuel elements and discussed on the water quality control record.

2 Coolant chemistry 2 1 Crud analysis

The crud samples have been taken from the spent fuel rod cladding surfaces of Korea Nuclear Unit 1 and analyzed the radioactivities of isotopes by using computerized multichannel analyzer. The summary of the analysis results have been shown in the Table 1 . The one of analysis results of each crud sample has been shown in Table 2

The radioactive materials of the corrosion products are mainly the Co-60, Mn-54, Co-58, and Cr-51 isotopes. The fission products are Zn-95, Nb-95, Ru-103, Cs-137, Cs-134, Sn-113, and Sb-124 isotopes.

The crud analyses of Korea Nuclear Unit 7 and 8 have been carried out and the analyses results have been shown in Table 3 and 4.

The radioactive materials of the corrosion products are also Co-58, Co-60, Fe-59, Mn-54, Cr-51, and Zr-95 isotopes.

2.2. Analysis of defected fuel and tramp uranium

The measurement and analysis of fission products in the primary coolant of nuclear power reactor have been carried out at the Korea Nuclear Unit 1 . The selected results of measured activity have been shown in Table 5.

The aalysis resultsfljof defected fuel and tramp uranium deduced from comparison of the calculated activity with measured activity have been shown in Table 5.

The average value of defected fuel for cycle 3 of Korea Nuclear Unit 1 is 9 7±0.8 elements.

Table 1. SPENT FUEL CRUD ANALYSIS RESULT

Sample

Table 1 Continued Table 2.Radionuclides Analysis of Crud Sample

Cycle 2 a Cycle3

» a ii

•3AMMA 1 -C02.3 > 19-JAN-82 SPECTRUM

THE DATA ARE ANALYZED BY DR. JAG CHOON YANG AND WITH GEL 10AM PROGRAM.

DETECTOR SYSTEM

O C ( L I ) E'UTECTOR OF CENTRAL LABC'KTORY.

KOREA ADVANCED ENERGY RESEARCH INSTITUTE CALIBRATION ES.CLB

EFFICIENCY OF 5TH POSITION LIBRARY L2O

START. STOP 50. 405O SENSCV.) 1O MULTIPLIER DECAY CORRECTED TO O9-DEC-32 OOiOOtOO

TIME OF COUNT TIME CORRECTED NUCLI&E COUNTING 2 S

4.1

Table 3. Crud Analysis Result of Korea Nuclear Unit 7 (pci/cc)

-Table 4 Crud Analysis Result of Korea Nuclear Unit 8

Table 5 Analysis Result of Defected Fuel and Tramp Uranium

Date

Measured Activity 0*Ct/g) .».,

2.3 Sipping test

We have analyzed the sipping test results of spent fuel elements for the cycle 3 of Korea Nuclear Unit 1. The detectors used to measure are Nal(Tl) and Ge(Li).

The detecting isotopes are 1-131 and Cs-137. The number of sipping tested fuel assemblies are 81 spent fuels.

The sipping test results have been shown in Table 6. The cumulative distribution of sipping test result of D-region [2]

has been shown in Fig.t. The detecting isotope is 1-131 and the detector is Nal(Tl).

The cumulative distribution of sippin« test results of D-region, cs-137 for detecting isotope, Nal(Tl) for detector, has been shown in Fig.2.

The cumulative distribution of sipping test results of D-region, 1-131 for detecting isotope, Ge(Li) for detector, has aeen shown in Fig.3.

2.4. Coolant history of reactor

The coolant histories for the Korea Nuclear Unit 1 reactor from cycle 3 to cycle 4 have been shown in Fig.4.

The boron and lithium concentrations and PH values for Korea Nuclear Unit 7 have been shown in Table 7.

Table 6. Comparison of Defected Fuel Analysis Result with Sipping Test Result

Sipping Tea Result Detector used

Analysis Result in this Work Number of failled fuel

9.7±0.8

»9 >9 —— »sagas 99 9e 9» BO so 70 so to «o 30 20 —— 10 —— 6 —— 2. — i 0^ Q.j! 8.( '

7 î

„ <006)

, X X X XX X X X x "

l l l I I I * I I I I I I I I I I I II I I

001 O O I O I O Z O S 12 S 10 20 JO « K) 60 70 » 90 93 98 »9 996*9» 9999

Fiçr.1 Cumulative Distribution of Sipping Test Result, D-Region, 1-131, N a l ( T l ) .

99 99 9 9 9 9 9 8 99 96 95 90 80 70 60 50 <0 30 20

' i l I—1———I——I———I——I—1—I—I—1——r- 5 2 I 0.5 0^ O.I 0(

H————I——I I I I Il 05 Of O.I 005 0( I

I ( D O S )

(009) * (ON

x ( DIS I

* <D07>

X 1039) ,xxx

i l l 1 1 x » * " " "i l l I I I I I

001 005 0 1 0 2 0 5 I 2 3 10 2 0 3 0 4 0 5 0 6 0 7 0 6 0 90 95 99 994999 9999

Fig 2 Cumulative Distribution of Sipping Test Results,D-Reion, Cs-137, Nal(Tl).

99

99.99 899998 99 96 «S 90 80 TO «0 » <p 30 005 Q.< I

1

m 3

(038) (009)

x <D2»

IID3SJ

* (014)

:**

/**

' l l l l l" l" I I I I I I I I I I I——L

0.01 0050.1 0,2 OS 12 5 10 10 ÎO 40 SO 6O 70 »O »0 93 99 9» SSA 993 99.99

Fig.3. Cumulative Distribution of Sipping Test Results, D-Region, 1-131, G e ( L i ) .

3.0

2.5

2.0

a, E 1.5

1.0

0.5

0.0

RECOMMENDED OPERATING RANGE

CXCtE 3

1200 1000 800 600 400 DCRON (ppm)

200

Fig. 4. Boron versus Lithium Concentrations in the Kori Unit 1 Reactor Coolant During Cycle 3 And 4.

100

Tab 1 e / Coolant Chemistry Data for Korean Nuclear Unit 7 3. Conclusion

As the results of crud analysis, the radioactive materials of corrosion products are mainly the Co-60, Mn-54, Co-58, and Cr-51 isotopes. This results are well agreed with the results Solomon [3] .

The analysis results of defected fuel and tramp uranium are in a fairly good agreement with the result of the sipping test during the refueling period for cycle 3 of Korea Nuclear Unit 1.

As we compare the crud analysis results with coolant histories of the end of cycles, we can see that the amount of crud materials are closely related to the water control.

References

C1) Jae-Choon Yang.etal, Study on the Release Mechanism of Nuclear Fission Products in Reactor Fuel, New Physics(Korean Physical Society) 25(4), 401(1985).

<7t K.R.Yang.etal, Water Chemistry of PWR Power Plants, KAERI/

RR-377/82, Korea Advanced Energy Research Institute (1983).

(3] Y.Solomon and J. Roesmer, Measurement of Fuel Element Crud Deposits in Pressurized Water Reactors, J. Nucl. Tech. 29,

166(1976).

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