Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
April 14, 1994
NRC INFORMATION NOTICE 94-31: POTENTIAL FAILURE OF WILCO, LEXAN-TYPE HN-4-L
FIRE HOSE NOZZLES
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert the addressees of the potential for failure of Lexan-
type HN-4-L fire hose nozzles. It is expected that recipients will review the
information for applicability to their facilities and consider actions, as
appropriate, to avoid similar problems. However, suggestions contained in
this information notice are not NRC requirements; therefore, no specific
action or written response is required.
Description of Circumstances
On August 3, 1992, the licensee for the H.B. Robinson facility experienced a
failure of a 1 1/2-inch Lexan-type HN-4-L fire hose nozzle during a routine
fire hose hydrostatic pressure test. Following the failure, the licensee
revised their procedures to require the use of a ball-style shutoff nozzle
during future pressurization tests. On June 17, 1993, the licensee
experienced another failure of a Lexan-type HN-4-L nozzle during a regularly
scheduled fire hose station flush. The nozzle failed when it was pressurized
to nominal firemain pressure. Following this event, the licensee replaced
Lexan-type HN-4-L nozzles with ball-style shutoff nozzles.
Discussion
During a fire hose pressurization test on August 3, 1992, the Lexan-
type HN-4-L nozzle attached to a hose being tested was shut to pressurize the
hose to the final test pressure of 1,756 kPa [254.7 psia]. With the hose
pressurized to approximately 1,204 kPa [174.7 psia], the nozzle failed.
Following a review of the event, the licensee revised their fire hose
hydrostatic test procedure to require the use of ball-style shutoff nozzles.
On June 17, 1993, a similar failure of a Lexan-type HN-4-L nozzle occurred
during a routine flush of an installed fire hose station. With the nozzle
shut and the fire hose charged to the nominal system pressure of 1,032 kPa
[149.7 psia], the nozzle failed.
9404080170. IN 94-31
April 14, 1994
Page 2 of 2
The nozzles were both 1 1/2-inch diameter, Lexan (polycarbonate) fog nozzles.
Originally, Wilco (Wilson and Cousins Company) manufactured these nozzles,
which are now manufactured by the A. Burks Pump Company. They are designated
as Model HN-4-L and are approved by Factory Mutual Insurance Company for fire
hose station use. The testing performed by Factory Mutual included a
hydrostatic test at 6,895 Kpa (1000 psi) and an operational test at pressures
up to 2,069 Kpa (300 psi).
Though the licensee does not track the installation of fire nozzles, it is
estimated that both nozzles had probably been in service for several years.
The nozzles consist of a stationary inner casing attached to the fire hose
fitting. An outer shell is threaded onto this inner casing. The outer shell
is twisted to adjust or start/stop flow. In both of the failures, the inner
casing separated at the third land for the inner casing-outer shell thread.
No indications of imminent failure were present in either failure. An
examination of the threaded area on some disassembled nozzles did not reveal
indications of cracking.
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
/S/'D BY CIGRIMES/FOR
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: C. Ogle, RII
(803) 383-4571
W. Orders, RII
(803) 383-4571
P. Madden, NRR
(301) 504-2854
Attachment:
List of Recently Issued NRC Information Notices
