|
Navy maintains U.S.S. Houston leak poses no risk
The U.S. Navy continues to maintain that Radio-active material that leaked from the U.S.S. Houston into Apra Harbor posed no risk to the safety of the public, marine life of the environment. Late Thursday, Adelup issued a press release announcing the fast attack submarine had leaked longer than initially reported. The Houston which travels to ports like Hawaii, Japan and Guam, leaked here for a little over a year.
In a statement issued this morning, the Navy has determined that an extremely small amount may have been released into the environment, but at no time did it pose a health risk. The release further stated that the release was less than the total amount of radioactivity contained in all of the smoke detectors installed in a typical family home.
Here is the Navy's statement released this morning:
The U.S. Navy has determined that an extremely small amount of
radioactivity may have been released into the environment during USS
HOUSTON's homeport periods at Apra Harbor, Guam starting in June 2006 to
her most recent departure. This was a total of 366 days in Apra Harbor.
The amount of radioactivity released to the environment during these
inport periods is less than 8 micro curies.
For perspective, the total amount of radioactivity released into the
environment as a result of valve weepage during these inport periods is
less than the total amount of radioactivity contained in all of the
smoke detectors installed in a typical family home. This extremely
small amount of radioactivity would have no adverse effect on human
health, marine life, or the environment. Extensive monitoring in Apra
Harbor has confirmed that U.S. nuclear-powered warship operations have
had no discernable effect on the radioactivity in the environment,
including during periods prior to, during, and after HOUSTON's most
recent departure.
On 17 July 2008, when USS HOUSTON (SSN 713) was in dry dock at Pearl
Harbor Naval Shipyard (PHNSY) for scheduled maintenance, about one
gallon of water spilled into the dry dock when a temporarily installed
mechanical fitting came loose. The water, which potentially contained
extremely low levels of radioactivity, spilled on the leg of a HOUSTON
Sailor in the dry dock.
Trained Shipyard personnel quickly responded to the situation and the
spill was contained on site. Using sensitive instruments, no detectible
radioactive contamination was found on the Sailor or in the dry dock.
In accordance with standard practice, the U.S. Navy called the State of
Hawaii, Department of Health to inform them of the small spill.
In the course of determining the source of the small spill, on 24 July
2008 the U.S. Navy completed formal valve leak tests and identified that
one of HOUSTON's shut valves was weeping water at a small rate above the
Naval Nuclear Propulsion Program's stringent design specifications.
Extensive analysis by a government nuclear laboratory, Knolls Atomic
Power Laboratory (KAPL), was required to determine that there was very
small weepage past this valve above its tight specification while
HOUSTON was operating. Such an extremely small weepage rate is not
expected to be identified by normal ship systems, which would reliably
detect larger leakage from the propulsion plant to protect the reactor
plant, the safety of the crew, the safety of the public, marine life,
and the environment.
From 24 through 31 July 2008 the Navy conducted an assessment to
determine the extent and duration of the weepage.
On 31 July 2008, KAPL and PHNSY & Intermediate Maintenance Facility
determined that the shut valve may have been weeping at a small rate and
may have released an extremely small amount of radioactivity into Pearl
Harbor, Guam, and Sasebo during HOUSTON's most recent visits to these
ports. The Government of Guam was notified on 31 July 2008 EDT.
Since 31 July 2008, the Navy has been working to determine the extent
and duration of the leak beyond these three most recent port visits.
Based on an analysis of ships data, the Navy has determined that the
valve has been steadily leaking a small amount above the stringent
design specification from June 2006 until HOUSTON was placed in dry dock
in July 2008.
This weepage was so small that it was below the limit of detection by
personnel on the ship and was indistinguishable by the ship from no
leakage at all. Data analysis by the ship is complicated by changes in
reactor plant power due to ship's operations and other factors that are
normal during plant operations. Extensive computational analysis by a
U.S. government nuclear laboratory, Knolls Atomic Power Laboratory
(KAPL), was required to determine that there was very small weepage past
this valve above its tight specification.
At no time was there a risk to the reactor plant, the safety of the
crew, the safety of the public, marine life, or the environment as a
result of these inport periods. The amount of radioactivity involved is
extremely small. The amount of naturally occurring radioactivity in the
seawater of a typical harbor is millions of times greater than the
radioactivity released during this event.
From June 2006 to the present, HOUSTON has spent a total of 366 days in
port in Guam. The amount of radioactivity released to the environment
during these inport periods is less than 8 micro curies. This amount of
radioactivity is determined by calculating the estimated weepage rate
and then accounting for the trace levels of radioactivity in this amount
of water. The total amount of radioactivity released into the
environment during these inport periods is less than the total amount of
radioactivity contained in all of the smoke detectors installed in a
typical family home.
The Navy routinely performs environmental monitoring in ports frequently
visited by U.S. nuclear powered warships, including Guam. Extensive
monitoring in Apra Harbor has confirmed that U.S. nuclear-powered
warship operations have had no discernable effect on the radioactivity
in the environment, including during periods prior to, during, and after
HOUSTON's most recent departure. Results of this monitoring are
forwarded to appropriate Government of Guam Officials for review.
|