U.S. Reactor Containment Technology: a Compilation of Current Practice in Analysis, Design, Construction, Test, and Operation, Volume 1 Page: 1-22
The following text was automatically extracted from the image on this page using optical character recognition software:
fission products. The failure of the primary system could, in many power-
reactor plants, result in core meltdown and dispersal of fission products
into the containment system. It is suggested therefore that the conse-
quence of failure of the primary system is potentially greater than that
of the failure of the reactor safety system, and its reliability and the
reliability of instrumentation upon which its integrity may be dependent
should be comparable to that of the safety system.
The containment system is the last barrier between the reactor and
the general public and is provided to protect the public when all other
barriers have failed. Since failure of this system to operate correctly
when correct operation is required will be catastrophic, its reliability
must be at least as great as that of any other reactor system safety de-
vice. The necessity in some systems for ventilating the containment
vessel imposes a reliability problem in that valves must close the venti-
lating ducts, and reliable closure depends on the correct operation of
instruments and control systems. The problem is aggravated by the require-
ment that all the valves must be tightly closed to effect containment.
This is in contrast to the reactor safety system that is usually required
to insert only a fraction of the total number of rods to effect shutdown.
Hanauer28 reviewed the closure systems of eight power-reactor containment
systems and found the reliability in several cases to be below that of a
reactor safety system.
220.127.116.11 Reliability in Operating Versus Shutdown Condition
There is a growing conviction that a reactor is safer in operation
than in the shutdown condition. In discussing the NRX and NRU reactors,
Breckon and Collins29 state that
"The (NRX) accident pointed out quite clearly that a re-
actor capable of operation but in a shut down state is poten-
tially more hazardous than when it is operating at full power,
a fact which has been borne out by other reactor accidents
throughout the world."
This conclusion would, of course, not be true for a fluid-fueled
reactor in which the fuel is drained from the reactor system when the
reactor is shut down. In any event, it is probably true that while a
shut down reactor may have a far greater chance of an accident, the magni-
tude of the accident potential under this condition is likely to be much
smaller than in the operating condition. Nevertheless, Canadian practice
is to do as much maintenance testing and fuel handling as possible with
the reactor in operation so that the first error will result in a notice-
able perturbation, and thus errors will be less likely to accumulate than
would be the case if testing and fuel handling were done with the reactor
Most reactors must be loaded and unloaded by manual manipulation of
the fuel. During such fuel-handling operations, the reactor may be with-
out the protection of the safety system and the pressure-vessel cover is
usually removed. In this condition the power reactor resembles the criti-
cal experiments in which a number of prompt-critical excursions have
resulted from errors in manual manipulation. The hazard is increased by
Here’s what’s next.
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Cottrell, William B. & Savolainen, A. W. U.S. Reactor Containment Technology: a Compilation of Current Practice in Analysis, Design, Construction, Test, and Operation, Volume 1, report, August 1965; Oak Ridge, Tennessee. (https://digital.library.unt.edu/ark:/67531/metadc101033/m1/50/: accessed March 18, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.