Information Notice No. 81-30: Velan Swing Check Valves
SSINS No. 6835
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
September 28, 1981
Information Notice No. 81-30: VELAN SWING CHECK VALVES
Description of Circumstances:
Recent occurrences with Velan swing check valves are described below.
1. On June 30, 1981, Public Service Electric & Gas Company reported (LER
81-035/01T) that on June 6, 1981, while a leak in the bonnet of a swing
check valve in the steam supply to the turbine driven auxiliary
feedwater pump at Salem Generating Station, Unit 2, was being repaired,
the valve was found to be internally damaged. The valve is a Velan
6-in. swing check valve (Type B14-2114 B-2TS).
The valve disk stud had broken and the valve disk was in the bottom of
the valve body. The valve also had cracks in the disk, cracked
bushings, a warped hinge pin, and all hinge pin holes were elongated.
The licensee inspected the corresponding swing check valve in the other
steam supply line and discovered similar damage. An inspection of the
corresponding swing check valves on Unit 1 also revealed similar damage
The licensee plans to radiologically examine the valves monthly until
a reason for the damage can be determined.
2. On July 31, 1981, Wisconsin Electric Power Company reported (LER
81-010/01T-O) that on July 14, 1981, while a check valve leakage test
at the Point Beach Nuclear Plant, Unit 1, was being performed, the
check valves closest to the reactor coolant system in the low head
safety injection lines were found to be leaking more than allowed by
the leakage acceptance criteria. The valves are Velan 6-in. 1500 psig
ASA swing check valves (Velan Drawing No. 78704).
The valves were disassembled and the disks were found to be stuck in
the full-open position due to interference between the disk nut
lockwire (disk wire) and the valve body. The disk nut and its shaft can
rotate freely, and, in certain random rotational positions, this
interference is likely to occur.
The licensee has replaced the disk wire with a cotter pin that will not
cause interference with the valve body for any rotational position.
Subsequent inspection of the other check valves in the low head safety
September 28, 1981
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was performed. These valves were found to be closed. The lock wires
were nevertheless replaced with cotter pins.
The drawing for the same valve used at the Prairie Island plant was
also checked. The drawing (Velan Drawing No. 78704) is annotated to
require that the lock wire be tack welded down (so it cannot interfere
with the valve body). Because this detail is not uniform on the subject
drawing and can vary from plant to plant, a verification and/or
changeout on this locking device may be necessary.
Additional occurrences with Velan swing check valves are described in IE
Bulletin 79-04, "Incorrect Weights for Swing Check Valves Manufactured by
Velan Engineering Corporation," and in Information Notice No. 80-41, "Failure
of Swing Check Valve in the Decay Heat Removal System at Davis-Besse Unit
This information is provided as notification of a potentially significant
matter. It is expected that recipients will review the information for
possible applicability to their facilities. No specific action or response
is requested at this time. If you have questions regarding this matter,
please contact the Director of the appropriate NRC Regional Office.
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