Bulletin 74-003: Failure of Structural or Seismic Support Bolts on Class I Components
BL74003
UNITED STATES
ATOMIC ENERGY COMMISSION
WASHINGTON, D.C. 20545
J. P. O'Reilly, Director of Region I
N. C. Moseley, Director of Region II
J. G. Keppler, Director of Region III
E. M. Howard, Director of Region IV
R. H. Engelken, Director of Region V
RO BULLETIN #74-3 "FAILURE OF STRUCTURAL OR SEISMIC SUPPORT BOLTS ON CLASS I
COMPONENTS"
The enclosed RO Bulletin #74-3 is forwarded for dispatch to all BWR and PWR
licensees with Operating Licenses and those licensees having an anticipated
fuel load date prior to January 31, 1975.
Harold D. Thornburg, Chief
Field Support & Enforcement Branch
Directorate of Regulatory Operations
Enclosure:
As stated
cc: D. F. Knuth, RO
J. G. Davis, RO
B. H. Grier, RO
A. Giambusso, L
J. Hendrie, L
D. J. Skovholt, L
.
To All BWR and PWR with current Operating Date: 3/22/74
Licenses and those having an anticipated DRO Bulletin #74-3
fuel load date prior to January 31, 1975.
Gentlemen:
The enclosed DRO Bulletin No. 3 "Failure of Structural or Seismic Support
Bolts on Class I Components" is sent to provide you with information
reported by Connecticut Yankee as an abnormal occurrence at The Haddon Neck
reactor facility.
This information may have applicability at your facility(ies). Action
requested on your part is identified in Section B of the enclosed Bulletin.
Sincerely,
Director
Enclosure:
DRO Bulletin #74-3
.
FAILURE OF STRUCTURAL OR SEISMIC SUPPORT BOLTS ON CLASS I COMPONENTS
We recently received information from the Connecticut Yankee Atomic Power
Company describing bolt failures found during routine in-service inspections
at the Haddam Neck pressurized water reactor which may relate to the
installation and serviceability of seismic support bolts or other seismic
support structures at your facility.
Description of Circumstances
A. During a visual inspection, several steam generator seismic support
holddown bolts were observed to be loose. Subsequent inspections by
ultrasonic and impact testing of all 256 bolts identified a total of 24
which had failed and were unable to perform their design function. A
preliminary evaluation indicated the bolts had failed in tension
apparently from over-torque during the original installation. It was
later ascertained by metallurgical and electron microscopic techniques
that the failures were the result of stress corrosion, associated with
the high pre-stressing, stress risers at the root of the bolt threads
and the presence of moisture originally from the concrete and
continuing from miscellaneous spills, leakages or high humidity
commonly found within containment areas.
In reviewing this problem, it was noted that Section XI of the Boiler
and Pressure Vessel Code does not specifically address the inspection
of-support structures for vessels except for the "support attachment
(vessel support skirts) which includes the welds to the vessel and the
base metal beneath the weld zone and along the support attachment
.
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for a distance of two base metal thicknesses."1/ Support members and
structures for piping, valves, and pumps within the system boundary
"whose structural integrity is relied upon to withstand the design
loads and seismic induced displacements" are subject to examination.2/
B. Action Requested
1. Since the various support structures for vessels within
containment are subject to the same environment as other support
structures described above, but are not subject to the same
examination, it is requested that,during your next scheduled
outage, you selectively examine a representative portion of the
vessel support members and structures, including the bolting
material for two Seismic Category I vessels (as defined in
Regulatory Guide 1.29) whose structural integrity is relied upon
to withstand design and seismic displacements. This examination
should include sufficient coverage of each support structure to
provide confidence of serviceability.
2. It is requested that you notify the RO Regional Office in writing
within 20 days of your proposed schedule for this inspection
including the date that your detailed written programs and
procedures will be available for RO inspection. Your program shall
include, but not be limited to: structures to be examined;
inspection methods to be used; and number of bolts per structure
examined.
1/ASME Boiler and Pressure Vessel Code; Section XI; Table IS-251: Para. H.
2/ Ibid; Para. K-2.
.
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3. If failures are revealed during your inspections, you are
instructed to promptly report these as "Abnormal Occurrences" in
accordance with the requirements of your license.
.
ENCLOSURE
Directorate of Regulatory Operations
Information Request No. 74-2
PWR MAIN STEAM LINE ISOLATION VALVES
In the past several months Regulatory Operations has received notification
of a number of abnormal occurrences involving main steam isolation valves at
various PWR facilities. Licensees' investigations following preoperational
tests and spurious valve closures have indicated that these valves,
particularly those of the check-valve type, may be subject to generic
failures.
To permit evaluation of the extent of the problem, the suitability of
specific valves for isolation purposes under postulated steam line rupture
accident conditions, and the appropriateness of possible remedial measures,
you are requested to provide the following specific information:
1. Facility name and unit number.
2. A line diagram or sketch showing the locations of the isolation
valve(s) with some identification of the type of each valve (check;
globe, gate; etc.).
3. Assembly or sectional drawings of each valve type with dimensions and
identification of material.
4. Name of the manufacturer of each valve type.
5. Steam line pressure at full power and at hot stand-by conditions,
compared with valve design pressure.
6. Functional design requirements contained in the original design
specifications for each valve.
7. An assessment of the adequacy of each valve type to perform the
isolation function under postulated steam line rupture accident
conditions.
8. Discussion of any operational malfunctions of each valve.
In your response to this request, please also include information relating
to modifications or other methods of resolution which are planned or which
may have been made to valves of this type installed, or scheduled to be
installed, in your facility(ies).
8011060831
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