Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 84-23
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
April 5, 1984
Information Notice No. 84-23: RESULTS OF THE NRC-SPONSORED
QUALIFICATION METHODOLOGY RESEARCH TEST
ON ASCO SOLENOID VALVES
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or
construction permit (CP).
Purpose:
This information notice is provided as an early notification of a
potentially significant event concerning the failure of two naturally aged
Automatic Switch Company (ASCO) solenoid valves. These valves are ASCO
models NP-8316 and NP-8344. The failure of these two naturally aged valves
occurred during the LOCA/MSLB (Loss-of-coolant accident/main steam line
break) simulation phase of a qualification methodology research test
conducted by the Franklin Research Center (FRC). It should be noted that
this information notice is not addressing the earlier concerns dealing with
the Viton/EPDM material used in ASCO solenoid valves as described in
previously published information notices. It is expected that recipients
will review the information for applicability to their facilities and take
appropriate action. A response is not required.
Description of Circumstances:
Recently the Nuclear Regulatory Commission (NRC), Office of Nuclear
Regulatory Research (RES) sponsored a qualification methodology research
test on seven ASCO solenoid valves. The test program was developed by FRC
for the NRC. This research test program resulted in a number of failures
which had not been experienced in previous qualification tests performed by
the manufacturer. The FRC test specimens consisted of seven different valve
models, of which five valve models were artificially aged, and two valve
models were naturally aged. The natural aging which was done by the
manufacturer, consisted of exposing the two test valve models in an air oven
at 140F (60C) for three years. The valves were pressurized with
nitrogen and valve solenoids were continuously energized.
The test program was patterned after the requirements of IEEE 323-1974,
344-1975, 382-1980, and NUREG-0588, Rev. 1, with the exception that the two
naturally aged valve models (model NP-8316-66E, and model NP-8344-A71E) were
not exposed to radiation preaging. All seven valves were subject to DBA
radiation followed by LOCA/MSLB simulation. The specified temperature/
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IN 84-23
April 5, 1984
Page 2 of 3
pressure profile for the simulated LOCA/MSLB exposure, and details of the
FRC Solenoid valves test program and failure analysis can be found in
NUREG/CR-3424 (published in November 1983.)
Of the seven valve models that were tested, one passed and six failed during
the LOCA/MSLB test. The valve model which passed was artificially aged and
had a metallic seat. Among the six valve models that failed, four models
were artificially aged and two valve models were naturally aged. Naturally
aged valve model NP-8344 failed after 14 minutes into the test, and
naturally aged valve model NP-8316 failed after 2.75 hours into the test.
Failure was defined as the inability of the valve to perform its function.
Failure of naturally aged valve NP-8344 was attributed to the elastomer
sticking to valve metallic parts. For naturally aged valve NP-8316, the
failure was attributed to the cumulative degradation of the elastomer
diaphragm.
Discussion:
The NRC staff has reviewed the FRC test results and has made the following
observations: (1) the nature of the FRC test is a qualification methodology
research test, which has allowed the valves to cycle at higher temperature
during thermal aging, and (2) that the actual temperature profiles during
both LOCA/MSLB transients were higher and longer in duration than
recommended by industry standards. The NRC staff concluded that the failures
of the FRC artificially-aged valves were inconclusive. However, the failure
of the two naturally aged valves (models NP-8316 and NP-8344) during the
recent FRC test cannot be discounted since they were not subjected to the
same severe preconditioning as the artificially aged valves.
Similar valve models as those naturally aged valves that failed the FRC test
were also tested by ASCO and Westinghouse (W) in 1982. The results of this
test were documented in ASCO Report AQR-67368, Rev. O, March 1982 and WCAP
8587 EQDP-HE2/HE5 Rev. 4, WCAP 8687 EQTR-HO2A/HO5 Rev. 2. In the ASCO/W
test, model NP-8344 failed and model NP-8316 passed. Both the 1983 NRC/FRC
test and the 1982 ASCO/W test were patterned after the same standards and
since model NP-8316 failed the recent NRC/FRC test, the NRC staff considers
that model NP-8316 may not be suitable for the environmental conditions and
operating time requirements as reported in the aforementioned ASCO/W test
reports. Westinghouse has been informed of these findings in a NRC letter
dated December 23, 1983 from R. Vollmer (NRC) to E. P. Rahe (Westinghouse).
Similar models of these same two valves were also tested in 1978 and
reported in Isomedix AQS report number 21678/TR-Rev. A. Applications in
which environmental conditions are enveloped by test conditions described in
this Isomedix AQS 21678/TR-Rev. A report, are considered acceptable.
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IN 84-23
April 5, 1984
Page 3 of 3
If you have any questions regarding this matter, please contact the Regional
Administrator of the appropriate NRC Regional Office, or this Office.
Edward L. Jordan, Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contacts: N. B. Le, IE
(301) 492-9673
A. Masciantonio, NRR
(301) 492-8205
Attachment:
List of Recently Issued IE Information Notices
