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Title: Reactor process water (PW) piping inspections, 1984--1990

Abstract

In July 1983, the NRC ordered the shutdown of five boiling water reactors (BWR's) because of concerns about reliability of ultrasonic examination for detecting intergranular stress corrosion cracking (IGSCC). These concerns arose because of leaking piping at Niagara Mohawk's Nine Mile Point which was attributed to IGSCC. The leaks were detected shortly after completion of ultrasonic examinations of the piping. At that time, the Dupont plant manager at Savannah River (SR) directed that investigations be performed to determine if similar problems could exist in SR reactors. Investigation determined that all conditions believed necessary for the initiation and propagation of IGSCC in austenitic stainless steel exist in SR reactor process water (PW) systems. Sensitized, high carbon, austenitic stainless steel, a high purity water system with high levels of dissolved oxygen, and the residual stresses associated with welding during construction combine to provide the necessary conditions. A periodic UT inspection program is now in place to monitor the condition of the reactor PW piping systems. The program is patterned after NRC NUREG 0313, i.e., welds are placed in categories based on their history. Welds in upgraded or replacement piping are examined on a standard schedule (at least every five years) while weldsmore » with evidence of IGSCC, evaluated as acceptable for service, are inspected at every extended outage (15 to 18 months). This includes all welds in PW systems three inches in diameter and above. Welds are replaced when MSCC exceeds the replacement criteria of more than twenty percent of pipe circumference of fifty percent of through-wall depth. In the future, we intend to perform flow sizing with automated UT techniques in addition to manual sizing to provide more information for comparison with future examinations.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Westinghouse Savannah River Co., Aiken, SC (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
5780000
Report Number(s):
WSRC-MS-90-308; CONF-9011174-4
ON: DE92009855
DOE Contract Number:  
AC09-89SR18035
Resource Type:
Conference
Resource Relation:
Conference: 32. meeting of the Weapons Agencies Nondestructive Testing Organization (WANTO), Aiken, SC (United States), 27-29 Nov 1990
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 36 MATERIALS SCIENCE; C REACTOR; REACTOR COOLING SYSTEMS; K REACTOR; L REACTOR; P REACTOR; ULTRASONIC TESTING; AUSTENITIC STEELS; DISSOLVED GASES; HEAT TRANSFER; HYDRAULICS; INSPECTION; INTERGRANULAR CORROSION; PIPES; STRESS CORROSION; WELDED JOINTS; ACOUSTIC TESTING; ALLOYS; CHEMICAL REACTIONS; COOLING SYSTEMS; CORROSION; ENERGY TRANSFER; FLUID MECHANICS; FLUIDS; GASES; HEAVY WATER MODERATED REACTORS; IRON ALLOYS; IRON BASE ALLOYS; JOINTS; MATERIALS TESTING; MECHANICS; NONDESTRUCTIVE TESTING; PRODUCTION REACTORS; REACTOR COMPONENTS; REACTORS; SOLUTES; SPECIAL PRODUCTION REACTORS; STEELS; TESTING; 220900* - Nuclear Reactor Technology- Reactor Safety; 220600 - Nuclear Reactor Technology- Research, Test & Experimental Reactors; 360105 - Metals & Alloys- Corrosion & Erosion

Citation Formats

Ehrhart, W S, Elder, J B, Sprayberry, R E, and Vande Kamp, R W. Reactor process water (PW) piping inspections, 1984--1990. United States: N. p., 1990. Web.
Ehrhart, W S, Elder, J B, Sprayberry, R E, & Vande Kamp, R W. Reactor process water (PW) piping inspections, 1984--1990. United States.
Ehrhart, W S, Elder, J B, Sprayberry, R E, and Vande Kamp, R W. 1990. "Reactor process water (PW) piping inspections, 1984--1990". United States. https://www.osti.gov/servlets/purl/5780000.
@article{osti_5780000,
title = {Reactor process water (PW) piping inspections, 1984--1990},
author = {Ehrhart, W S and Elder, J B and Sprayberry, R E and Vande Kamp, R W},
abstractNote = {In July 1983, the NRC ordered the shutdown of five boiling water reactors (BWR's) because of concerns about reliability of ultrasonic examination for detecting intergranular stress corrosion cracking (IGSCC). These concerns arose because of leaking piping at Niagara Mohawk's Nine Mile Point which was attributed to IGSCC. The leaks were detected shortly after completion of ultrasonic examinations of the piping. At that time, the Dupont plant manager at Savannah River (SR) directed that investigations be performed to determine if similar problems could exist in SR reactors. Investigation determined that all conditions believed necessary for the initiation and propagation of IGSCC in austenitic stainless steel exist in SR reactor process water (PW) systems. Sensitized, high carbon, austenitic stainless steel, a high purity water system with high levels of dissolved oxygen, and the residual stresses associated with welding during construction combine to provide the necessary conditions. A periodic UT inspection program is now in place to monitor the condition of the reactor PW piping systems. The program is patterned after NRC NUREG 0313, i.e., welds are placed in categories based on their history. Welds in upgraded or replacement piping are examined on a standard schedule (at least every five years) while welds with evidence of IGSCC, evaluated as acceptable for service, are inspected at every extended outage (15 to 18 months). This includes all welds in PW systems three inches in diameter and above. Welds are replaced when MSCC exceeds the replacement criteria of more than twenty percent of pipe circumference of fifty percent of through-wall depth. In the future, we intend to perform flow sizing with automated UT techniques in addition to manual sizing to provide more information for comparison with future examinations.},
doi = {},
url = {https://www.osti.gov/biblio/5780000}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 1990},
month = {Mon Jan 01 00:00:00 EST 1990}
}

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