Download pdf - JAEAjolissrch-inter.tokai-sc.jaea.go.jp/pdfdata/JAEA... · Hiroshi OHUCHI and Masayuki SHINOZAKI Department of HTTR Oarai Research and Development Center Japan Atomic Energy Agency

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Improvement of Helium Sampling System in HTTR

Kenji SEKITA, Misao KUROHA , Koichi EMORI , Masaaki KONDO

Hiroshi OHUCHI and Masayuki SHINOZAKI

Department of HTTR

Oarai Research and Development Center

Japan Atomic Energy Agency

Oarai-machi,Higashiibaraki-gun,Ibaraki-ken

(Received January 7, 2008)

Graphite structures are used as the HTTR core internals. Graphite structures

have high heat resistant property but strength degrades easily by oxidization. To prevent the

oxidization of graphite structures, impurity concentrations in the helium coolant are

controlled strictly. The helium sampling system is installed to measure the impurity

concentrations in the helium coolant.

Seal-oil leakage occurred at the rod seal mechanism of gas compressor in helium

sampling system. The reasons are degradation of the seal material and contaminant abrasion

powder of the grand-packing. Thus, the material of the seal material was changed and

contaminant was decreased. A long term operation became possible by these

countermeasures. Moreover, reliable data can be obtained and efficient impurity control is

enabled due to renewal of data acquisition control computer of gas chromatograph mass

spectrometer and improvement of liquid nitrogen trap.

This report describes the improvement items of the helium sampling system.

Keywords: HTTR , Maintenance , Helium Sampling System , Impurity of Helium

Gas Compressor

Research Staff on Loan

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Contents

1. Introduction

2. Outline of helium sampling system

2.1 Primary Helium Sampling System

2.2 Secondary Helium Sampling System

3. Overhaul of gas compressor

3.1 Structures of gas compressor

3.2 Conditions of overhaul of gas compressor

3.3 Occurrence details of seal-oil leak

3.4 Investigation of cause of seal-oil leak

3.5 Counter measure

4. Improvement of Data Acquisition Control Computer

4.1 The point at issue

4.2 Function of renewal system

4.3 Method of software

4.4 Method of file definition

4.5 Result of renewal system

5. Improvement on Liquid Nitrogen Trap

5.1 Condition of the past

5.2 Method of renewal Liquid Nitrogen Trap

6. Conclusion

Acknowledgements

References

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