skip to main content

Title: Actuator system history of safety rod lower latch problems review of latch inspection video tapes

During pre-restart testing the safety rod at position X26-YlO bound after being driven approximately two (2) feet out of the reactor. Subsequently, the rod was manually returned to it's seated position. Inspection of the lower latch showed that the latch locking plunger button (screwed on to the bottom of the plunger shaft and retained by a pin through a hole drilled through the button and the plunger shaft) was missing. The shaft failed through the hole drilled for the retaining pin. The button, with the retaining pin intact, was found lodged between the safety rod upper adapter collar and the top of the safety rod thimble top fitting. Analysis of the safety rod latch and accompanying forest guide tube design provided assurance that this type of failure would not cause binding during the scramming'' of the safety rods. Inspection of all of the K'' safety rod lower latches revealed six other latches with missing plunger buttons, and nine with other non-conformances which required latch replacement. A history search conducted by Reactor Engineering Design, Components Handling Group, is included in this report. The history search shows that latch design modifications, as a part of initial development of the latch system andmore » later to improve the delatching operation, were made from 1950 to 1960. These modifications created a condition where latch damage could occur. Video tapes were made during inspection of the safety rod latches in K area and control rod latches in L area. These tapes were reviewed by Reactor Engineering Design Components Handling engineers. The reviews were used for correlation of latch problems reported by the engineers/mechanics making the inspections. The K area tapes showed inspection of 65 of the 66 safety rod latches. The review of the tapes showed the plunger buttons to be missing from five latches. RED-CH reviewed the L Area video taped inspection of 35 control rod clusters (245 latches). No non-conformances were noted.« less
Authors:
Publication Date:
OSTI Identifier:
7232872
Report Number(s):
WSRC-TR-92-42-003
ON: DE92019920
DOE Contract Number:
AC09-89SR18035
Resource Type:
Technical Report
Research Org:
Westinghouse Savannah River Co., Aiken, SC (United States)
Sponsoring Org:
DOE; USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; K REACTOR; REACTIVITY INSERTIONS; SCRAM RODS; L REACTOR; CONTROL ELEMENTS; ACTUATORS; CONNECTORS; FAILURES; INVESTIGATIONS; REACTOR SAFETY; REACTOR START-UP; VIDEO TAPES; ADMINISTRATIVE PROCEDURES; CONDUCTOR DEVICES; ELECTRICAL EQUIPMENT; EQUIPMENT; HEAVY WATER MODERATED REACTORS; MAGNETIC STORAGE DEVICES; MAGNETIC TAPES; MEMORY DEVICES; OPERATION; PRODUCTION REACTORS; REACTOR COMPONENTS; REACTOR OPERATION; REACTORS; SAFETY; SPECIAL PRODUCTION REACTORS; START-UP 220900* -- Nuclear Reactor Technology-- Reactor Safety; 220400 -- Nuclear Reactor Technology-- Control Systems; 220600 -- Nuclear Reactor Technology-- Research, Test & Experimental Reactors