[permalink] [id link]
In the PWR, these neutron absorbing solutions are stored in pressurized tanks ( called accumulators ) that are attached to the primary coolant system via valves ; a varying level of neutron absorbent is kept within the primary coolant at all times, and is increased using the accumulators in the event of a failure of all of the control rods to insert, which will promptly bring the reactor below the shutdown margin.
from
Wikipedia
Some Related Sentences
PWR and neutron
Most BWR and PWR commercial reactors use uranium enriched to about 4 % U-235, and some commercial reactors with a high neutron economy do not require the fuel to be enriched at all ( that is, they can use natural uranium ).
( This is in contrast to early Soviet civil PWR designs where embrittlement occurs due to neutron bombardment of a very narrow pressure vessel.
* Because water acts as a neutron moderator, it is not possible to build a fast neutron reactor with a PWR design.
Usually there are also other means of controlling reactivity: In the PWR design a soluble neutron absorber ( boric acid ) is added to the reactor coolant allowing the complete extraction of the control rods during stationary power operation ensuring an even power and flux distribution over the entire core.
PWR and are
Some are evolutionary from the PWR, BWR and PHWR designs above, some are more radical departures.
Two things are characteristic for the pressurized water reactor ( PWR ) when compared with other reactor types: coolant loop separation from the steam system and pressure inside the primary coolant loop.
In a PWR, there are two separate coolant loops ( primary and secondary ), which are both filled with demineralized / deionized water.
PWR fuel bundles are about 4 meters in length.
* PWR reactors are very stable due to their tendency to produce less power as temperatures increase ; this makes the reactor easier to operate from a stability standpoint.
In both the PWR and the BWR there are secondary systems ( and often even tertiary systems ) that will insert control rods in the event that primary rapid insertion does not promptly and fully actuate.
Control rods are usually combined into control rod assemblies — typically 20 rods for a commercial Pressurized Water Reactor ( PWR ) assembly — and inserted into guide tubes within a fuel element.
In pressurised water reactors ( PWR ), they are inserted from above, the control rod drive mechanisms being mounted on the reactor pressure vessel head.
The village itself is overshadowed by two separate nuclear power stations, the Magnox Sizewell A and Pressurized Water Reactor ( PWR ) Sizewell B, which are readily visible from the nearby holiday beaches.
There are three varieties of light water reactors: the pressurized water reactor ( PWR ), the boiling water reactor ( BWR ), and ( most designs of ) the supercritical water reactor ( SCWR ).
The Soviet Union also independently developed their version of the PWR in the late 1950s, and it became known as the VVER ; because of this, Russian-designed PWRs are known in the West as VVERs, to denote their independent origin, and certain national design distinctions from Western PWRs.
The main design objectives of the generation III EPR design are increased safety while providing enhanced economic competitiveness through improvements to previous PWR designs scaled up to an electrical power output of around 1650 MWe ( net ) with thermal power 4500 MWt.
PWR containments are typically large ( up to 10 times larger than a BWR ) because the containment strategy during the leakage design basis accident entails providing adequate volume for the steam / air mixture that results from a loss-of-coolant-accident to expand into, limiting the ultimate pressure ( driving force for leakage ) reached in the containment building.
Boiling water reactors ( BWRs ) are the second most common form of light water reactor with a direct cycle design that uses fewer large steam supply components than the pressurized water reactor ( PWR ), which employs an indirect cycle.
PWR and stored
In this event there is a high danger of hydrogen explosions, threatening structural damage and / or the exposure of highly radioactive stored fuel rods in the vicinity outside the plant in pools ( approximately 15 tons of fuel is replenished each year to maintain normal PWR operation ).
PWR and pressurized
This and the risks posed by liquid sodium in the event of an accident at sea led Admiral Rickover to select the PWR ( pressurized water reactor ) as the standard US naval reactor type.
PWR fuel bundle This fuel bundle is from a pressurized water reactor of the nuclear passenger and cargo ship NS Savannah | NS Savannah.
It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor ( PWR ), also a type of light water nuclear reactor.
In commercial reactor operations, this emergency shutdown is often referred to as a " SCRAM " at boiling water reactors ( BWR ), and as a " reactor trip " at pressurized water reactors ( PWR ).
Like all operational U. S. naval reactors it was a pressurized water reactor ( PWR ) design.
: The BR3 nuclear reactor was a pressurized water reactor ( PWR ) that produced its first chain reaction in 1962.
The EPR is a third generation pressurized water reactor ( PWR ) design.
PWR and called
Nuclear fission is also used as a heat source for generating steam, either directly ( BWR ) or, in most cases, in specialized heat exchangers called " steam generators " ( PWR ).
PWR and primary
Unlike a PWR, there is no primary and secondary loop.
In a PWR, the primary coolant ( water ) is pumped under high pressure to the reactor core where it is heated by the energy generated by the fission of atoms.
Light water is used as the primary coolant in a PWR.
* PWR turbine cycle loop is separate from the primary loop, so the water in the secondary loop is not contaminated by radioactive materials.
In category B ( 2 + 3 + 4 ) is the surge line, which connects the hot leg with the pressurizer and helps to control the pressure in the primary loop of a PWR and uses a moving working fluid when fulfilling its mission.
PWR and system
* The pressurized-water reactor ( PWR ) design developed by the AEC was a heterogeneous, water-cooled and water-moderated, stainless steel system, using highly enriched ( 93 %) uranium dioxide mixture as fuel.
PWR and is
All reactors will be compared to the Pressurized Water Reactor ( PWR ), as that is the standard modern reactor design.
:: A BWR is like a PWR without the steam generator.
A boiling water reactor is cooled and moderated by water like a PWR, but at a lower pressure, which allows the water to boil inside the pressure vessel producing the steam that runs the turbines.
Instead of using a single large pressure vessel as in a PWR, the fuel is contained in hundreds of pressure tubes.
* PWR technology is favoured by nations seeking to develop a nuclear navy, the compact reactors fit well in nuclear submarines and other nuclear ships.
The main difference between a BWR and PWR is that in a BWR, the reactor core heats water, which turns to steam and then drives a steam turbine.
PWR and kept
These reactors can function much like a PWR in terms of efficiency, and do not require much high pressure containment, as the liquid metal does not need to be kept at high pressure, even at very high temperatures.
PWR and at
File: Donald Cook Nuclear Power Plant 1993. jpg | The twin PWR reactor containments at the Cook Nuclear Plant in Michigan
0.163 seconds.