Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
Accession No.:
8107230039
IN 81-36
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
December 3, 1981
Information Notice No. 81-36: REPLACEMENT DIAPHRAGMS FOR ROBERTSHAW
VALVE (MODEL NO. VC-210)
Description of Circumstances:
The Georgia Power Company's Hatch 1 facility experienced problems in early
July 1981 with the Robertshaw Diaphragm Control Valve (Model No. VC-210)
installed in the Terry Turbine Mechanical Hydraulic Overspeed Complex which
contributed toward unreliability of the High Pressure Coolant Injection
(HPCI) system. During a routine inspection of the valve, it was discovered
that the diaphragm supplied by Robertshaw was enlarged and leaking oil. The
diaphragm was replaced on July 12, 1981 and failed again on July 21 and
August 11, 1981. The cause of the failures was determined to be
incompatibility of a neoprene replacement diaphragm, supplied by Robertshaw,
with oil in the hydraulic overspeed complex. Following the August 11, 1981
failure, a fabric-reinforced Buna-N diaphragm was installed. The diaphragm
satisfied the following service conditions:
o Compatible with the turbine oil recommended by the turbine vendor
o 40 psig maximum service pressure
o 250F maximum service temperature
o 1000 minimum cycles
Replacement Buna-N diaphragms are available from Terry Corporation or
through the General Electric Company. An order placed directly with
Robertshaw will result in the supply of a thin, non-reinforced neoprene
diaphragm with reduced duty cycle life because the valves are supplied for
other applications. We understand that the reinforced Buna-N diaphragm
should be identified as Terry piece No. 890151AO1 on the purchase order.
Also, if a replacement Robertshaw Valve (Model No. VC-210) is ordered (Terry
piece No. 107282AO1), it is necessary to separately order the reinforced
diaphragm (Terry piece No. 890151AO1). The diaphragm is shown in the Terry
HPCI Instruction Manual, Section 15-M-14, Instruction for Robertshaw
Diaphragm Control Valve No. VC-210, Figure 14, Part 4.
This information notice on replacing diaphragms is being provided as an
early notification of a potentially significant matter. This experience
with diaphragm failures serves as a reminder that a single material change
may adversely affect safety system reliability. Such a change may reduce
service life or negate environmental qualification. Each component or
material change in a system important to safety should be carefully reviewed
in order to assure system operability. Recipients should review the
information for possible applicability to their facilities.
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IN 81-36
December 3, 1981
Page 2 of 2
No written response to this information notice is required. For additional
information regarding this matter, contact the Regional Administrator of the
appropriate NRC Regional Office.
Attachment:
Recently issued IE Information Notices
