ML19317G655
| ML19317G655 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/09/1972 |
| From: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Davis E SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 8003250710 | |
| Download: ML19317G655 (4) | |
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ATTN:
E. K. Davis, General Counsel R. C. DeYoung, DRL 6201 S Street, P. O. Box 15830 F. Schroeder, DRL Sacramento, California 93813 T. R. Wilson, DRL
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- As you know, an event occurred at a foreign proasurized water power repit'or'in which an unusual corrosion meehamien oecurred whom prolonge'd',
. leakage of berated reactor coolant onto the reactor vessel head was a
undetected. ~ Subsequent tests have indicated that this serreeion potential,
- might exist under certain conditions when borated fluid has prolonged 'een! " "
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To preclude additional experiences of this type, an appropriate program of inservice inspection should be implemented to detect smeh effects at an i
early stage. The ASNi, Code Committee for Inservice Inspection in con-sidering revision of the ASHE Code for Iuservice Inspection of Nuclear L
,Enestors. However, as"an~' interim measure,'we believe,that the inspection
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w Recommended PWR Inservice Inspection Program for Detection of Effects of~ Reactor Coolant Leak.ge A.
Inspection Requirements (1) Prior to reactor startup following each refueling outage, c11 pressure-retaining components of the reactor coolant pressure boundary shall be visually examined for evidence of reactor coolant leakage while the system is under a test pressure not less than the nominal system operating pressure at rated power.
This examination (which need not require removal of. insulation) shall be ~ performed by inspecting (a) the exposed surfaces and joints of -insulations, and (b) the floor areas (or equipment) directly underneath these components.
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At locations where reactor coolant leakage is normally expected and collected (e.g., valve stems, etc.), the examination shall verify that the leakage collection system is operative and leaktight.
(2) During the conduct of the examinations of (1) above, particular attention shall be given to the insulated areas of components constructed of ferritic steels to detect evidence of boric acid residues resulting from reactor coclant leakage which might have accumulated during the service period preceding the refueling outage.
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. (3) The visual examinations of (1) and (2) above shall be conducted in conformance with the procedures of Article IS-211 of Section XI of the ASME Boiler and Pressure Vessel Code.
B.
Corrective Measures (1) The source of any reactor coolant leakage detected by the examina-tions of A(1) above shall be located by the removal of insulation where necessary and the following corrective measures applied:
(a) Normally expected leakage from component parts (e.g., valve stems) shall be minimized by appropriate repairs and mainten-ance procedures. Where such leakage may reach the surfc.ce of
'ferritic components of the reactor coolant pressure boundary, the leakage shall be suitably channeled for collection and disposal.
(b) Leakage from through-wall flaws in the pressure-retaining mem-brane of a component shall be eliminated, either by corrective repairs or by component replacement. Such repairs shall con-form with the requirements of Article IS-400 of Section XI of the ASME Boiler and Pressure Vessel Code.
(2). In the event boric acid. residues are detected by the examinations of A(2) above, insulation from ferritic steel components shall be removed to the extent necessary for examination of the component
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. surfaces wetted by reactor coolant-icakage to detect evidence of corrosion.
The following corrective measures shall be applied:
(a) An evaluation of the effect of any corroded area upon the structural integrity of the component shall be performed in accordance with the provisions of Article IS-311 of Section XI Code.
(b) Repairs of corroded areas, if necessary, shall be performed in accordance with the procedures of Article IS-400 of
'Section XI Code.
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