Metallurgical Failure Analysis of MH-1A Reactor Core Hold-Down Bolts

Abstract

The Naval Research Laboratory (NRL), at the request of the U.S. Army Engineer Power Group (USAENPG), has performed a failure analysis on two MH-1A reactor core hold-down bolts that broke in service. Adherence to fabrication specifications, post-service properties and possible causes of bolt failure were investigated. The bolt material was verified as 17-4PH precipitation hardening stainless steel. Measured bolt dimensions also were in accordance with fabrication drawing specifications. Bolt failure occurred in the region of a locking pin hole which reduced the bolt net section by 47 percent. The failure analysis indicates that the probable cause of failure was net section overloading resulting from a lateral bending force on the bolt. The analysis indicates that net section overloading could also have resulted from combined tensile stresses (bolt preloading plus differential thermal expansion). Recommendations are made for improved bolting.

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 1976
Accession Number
ADA033436

Entities

People

  • Henry E. Watson
  • J. Russell Hawthorne

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Dispersion Hardening
  • Engineering
  • Engineers
  • Fabrication
  • Failure Analysis
  • Failure Mode And Effect Analysis
  • Hardening
  • Materials
  • Mechanical Working
  • Reactor Cores
  • Specifications
  • Stainless Steel
  • Steel
  • Tensile Properties
  • Tensile Strength
  • Tensile Testing
  • Yield Strength

Readers

  • Electrical Engineering
  • Metallurgy
  • Structural Health Monitoring of Composite Structures.