The following relates to the nuclear power generation arts, nuclear power facility arts, nuclear reactor facility layout arts, and related arts.
Constructing a nuclear power facility is an extensive undertaking Initial concept through plant design and construction to generation of electrical power output can take in excess of a decade or longer and can cost hundreds of millions of dollars or more.
A nuclear power facility is designed to be a secure site. An emergency core cooling system (ECCS) is designed in conjunction with the nuclear reactor to safely shut down the nuclear reactor in the event of a loss of coolant accident (LOCA), loss of heat sink accident, or other event potentially impacting safety. Additionally, a nuclear power facility can be an attractive target for terrorists, violent activist groups, or the like. Accordingly most countries take steps to secure nuclear power facilities against external attack.
In the United States, regulations promulgated by the Nuclear Regulatory Commission (NRC) specify rules for securing a nuclear power facility against external attack. See, e.g. 10 C.F.R. Part 73 (available at http://www.nrc.gov/reading-rm/doc-collections/cfr/part073/, last accessed Jan. 28, 2011). In accordance with NRC regulations, a protected area is defined, whose perimeter is protected by physical barriers limiting access into the protected area. 10 C.F.R. §73.55(e)(8). Vital areas including at least the reactor control room, the spent fuel pool, and certain critical alarm components are located within the protected area. 10 C.F.R. §73.55(e)(9). An isolation zone is maintained in outdoor areas adjacent to a protected area perimeter barrier. 10 C.F.R. §73.55(e)(7). The isolation zone is sized and designed to permit unobstructed observation and assessment of activities on either side of the protected area barrier, and is monitored with suitable intrusion detection equipment capable of detecting and recording attempted or actual penetration of the protected area perimeter barrier before completed penetration of the protected area perimeter barrier. Id.
While NRC regulations specify certain aspects of nuclear facility security, it is recognized that each facility presents unique geographical, terrain, facility size, and other considerations. Accordingly, a site-specific security plan is developed for each nuclear power facility. See generally C.F.R. Title 10 Part 73.
Jurisdictions outside of the United States typically have an analog regulatory agency to the NRC which promulgates regulations for securing nuclear power facilities.
In accordance with certain aspects disclosed herein, an apparatus comprises: a nuclear island including at least one nuclear reactor; a turbine island including at least a turbine building housing at least one turbine driven by steam generated by the nuclear reactor; a protected area having a perimeter protected by at least one fence; and an isolation zone surrounding the protected area and including intrusion detection devices configured to detect unauthorized approach toward the protected area. The nuclear island is disposed inside the protected area, and the turbine island is disposed outside of and spaced apart from the protected area.
In accordance with certain aspects disclosed herein, an apparatus comprises: a nuclear island including at least a nuclear reactor; a turbine building housing at least one turbine driven by steam generated by the nuclear reactor; a protected area having a perimeter protected by at least one fence; and an isolation zone surrounding the protected area and including intrusion detection devices configured to detect unauthorized approach toward the protected area. The isolation zone includes an engagement space surrounding the protected area and has a physical barrier field at least 30 feet wide and a sensor array surrounding the engagement space and configured to detect unauthorized approach toward the engagement space.
In accordance with certain aspects disclosed herein, an apparatus comprises a nuclear island including at least a nuclear reactor, and a turbine island including at least one turbine driven by steam generated by the nuclear reactor. The nuclear island and the turbine island are spaced apart from each other. The spacing between the nuclear island and the turbine island is 50 feet in some embodiments, and more preferably 100 feet, and still more preferably 130 feet. In some embodiments the nuclear island is maintained at a higher security level than the turbine island.
In accordance with certain aspects disclosed herein, an apparatus comprises: at least one nuclear reactor; at least one turbine driven by steam generated by the nuclear reactor; and an ultimate heat sink disposed underground and in operative communication with the nuclear reactor.
A nuclear power facility is typically designed for a particular electrical power output, which sets the size and other characteristics of the nuclear reactor and associated radiation containment and emergency core cooling system (ECCS), the electrical power-generating turbine or turbines, and so forth. The reactor is located in a containment building, critical ECCS components and rector support systems (i.e., spent fuels, rad waste) are located inside or closely proximate to the containment building thus forming a “nuclear island”. Remaining components (i.e., the “balance of plant”) including turbines, condensers, the electrical power distribution grid (i.e., the “switchyard”), are located near the nuclear island. Turbines for generating electrical power are driven by steam generated by the nuclear island, and are housed in a turbine building in close proximity to the nuclear island. This minimizes the lengths of steam lines running to the turbine building and feedwater lines running to the nuclear island, thus minimizing transient heat loss, piping considerations, and parasitic power loss (i.e., pumps) within this linkage, and enables the nuclear island and turbine building to constitute a single contiguous protected area for security purposes. The facility site is selected based on various considerations such as geographic proximity to power customers, foundational building support, seismic stability, availability of water for cooling, and so forth.
Facility design also incorporates security, especially for “vital equipment”, which is defined by the Nuclear Regulatory Commission (NRC) as “any equipment, system, device, or material, the failure, destruction, or release of which could directly or indirectly endanger the public health and safety by exposure to radiation. Equipment or systems which would be required to function to protect public health and safety following such failure, destruction, or release are also considered to be vital.” 10 C.F.R. §73.2. All vital equipment must be located in vital areas which in turn must be located in a protected area. 10 C.F.R. §73.55(e)(9). The protected area is a limited access area that is routinely patrolled by security personnel and is protected by physical barriers. See 10 C.F.R. §73.55(e)(8). The protected area is in turn surrounded by an isolation zone in outdoor areas that is sized to enable unimpeded observation of activities in both the isolation zone and the protected area, and is monitored with automated (and recording) intrusion detection sensors and alarms. Jurisdictions outside the United States are typically governed by similar security regulations or guidelines.
Conventionally, the nuclear power facility is constructed with a compact layout, with the turbine building and closely proximate nuclear island forming the core of a contiguous protected area. In some facility layouts, other portions of the balance of plant such as the switchyard and/or condensers are also included within the protected area. To accommodate elevated structures such as roof-mounted chillers for the turbine building, guard towers are established at suitable locations near the protected area perimeter to ensure that security personnel have continuous, unimpeded, and overlapping view of the entire protected area perimeter.
As disclosed herein, the conventional approach toward nuclear power facility layout has certain disadvantages, which are overcome by improvements disclosed herein.
In existing layouts for nuclear power facilities, operation and maintenance costs are high. For example, security costs are estimated to be approximately $25-30 million per year. This cost can be problematic for smaller nuclear power facilities, such as proposed small modular reactor (SMR) designs that produce no more than 300 megawatts (electrical). Moreover, the use of guard towers can be problematic since personnel posted in the guard towers are sedentary, which is not conducive to continual alertness that is desired of security personnel. In view of this, stationary guard postings ideally should have a personnel rotation every two hours or so. As stationary locations, guard towers near the perimeter are also known and well-defined targets for any external attack.
Existing nuclear plant facility layouts also complicate construction, maintenance, repair, and upgrade operations. Any work performed on the nuclear island, or in the turbine building, or anywhere else within the protected area must be performed by personnel who are cleared to work in the protected area. Where work is performed by contractors or other “outside” personnel, these personnel must be escorted while inside the protected area. Moreover, major upgrades within the protected area, such as adding a new turbine to a turbine island within the protected area of an existing facility, may require review and approval by one or more governing regulatory agency.
Still further, while existing nuclear power facilities are compact, they place substantial operational components within the protected area. This leads to a relatively large number of personnel present inside the compact protected area, which can be problematic in terms of security, personnel evacuation procedures, and so forth.
With reference to
The secondary coolant steam flows via a steam line from the nuclear island to the turbine island to drive a turbine (or, turbine/electrical generator assembly) to generate electricity that is distributed to customers or other end users by the switchyard. In some embodiments the secondary coolant water flows in a closed loop path wherein the steam is condensed back into liquid water (i.e., liquid secondary coolant water) at the turbine island or condensers 21 and flows back to the nuclear island via a feedwater line. The steam line and optional feedwater line passes between the nuclear island and the turbine island via utility trenches 22.
It is to be understood that although diagrammatic
With continuing reference to
As seen in
Regarding item (1), the turbine island is not a vital area because the failure, destruction, or other compromising of the turbine island could not directly or indirectly lead to a release of radiation, and the turbine island is not required to function to protect public health and safety during any cognizable emergency event. Cf 10 C.F.R. §73.2. The turbine is driven by steam generated by the nuclear island; however, the steam driving the turbine is secondary coolant that is not contaminated with any radioactive material. A break in (or other failure or shutdown of) the steam line running from the nuclear island to the turbine island, or a break in (or other failure or shutdown of) the feedwater line running from the turbine island to the nuclear island, would not cause (either directly or indirectly) a release of radioactive material. At most, such a break or failure or shutdown could constitute a loss of heat sink event in which heat sink of the nuclear reactor by flow of secondary coolant in the steam generator might be compromised. The emergency core cooling system (ECCS) disposed with the reactor inside the containment building accommodates any loss of heat sink event by immediately shutting down the reactor, depressurizing any transient pressure rise caused by the loss of heat sink, and initiating cooling of the reactor core. The ECCS performs this shutdown using shutdown control rods, soluble poison injection, steam condensers located within the containment building, cooling water stored in a refueling water storage tank (RWST) located within the containment building, or other suitable apparatus, without releasing any primary coolant into the containment building ambient (much less into the external environment).
Regarding item (2), it is recognized herein that the turbine and related components can be positioned relatively far away from the nuclear island. This arrangement takes advantage of the ability to begin construction on the balance of the plant (i.e., structures outside of the nuclear island) in the pre-licensing stage, and supports parallel construction of the nuclear island with the balance of plant thereafter, thereby enabling realization of otherwise unobtainable construction benefits.
Conventionally, the turbine is located in close proximity to the nuclear island in order to minimize the length of the steam line running from the nuclear island to the turbine building. The rationale for this is that the steam line carries steam heated by the nuclear reactor via the steam generator, and so a longer steam line leads to more heat loss and lowered efficiency. However, comparison with other types of facilities, such as fossil fuel facilities, indicates that this concern is misplaced and that a steam line of order 100 feet or longer is feasible without problematic loss of heat.
In some embodiments the steam line and the feedwater line are at or below ground level, e.g. in the illustrative utility trenches 22 in
While a facility at lower elevation (e.g., partially or wholly subterranean) is generally considered to be vulnerable to attack from a higher elevation, it is recognized herein that a partially or wholly subterranean facility has certain advantages from a security standpoint. By partially or wholly burying the nuclear island and placing the turbine outside of the protected area, the maximum elevation of the protected area can be made low, e.g. less than 20 feet in some embodiments, and less than 10 feet in some embodiments. This reduces the potential of having any obstructed view in the protected area. Indeed, in some embodiments it is contemplated to have no guard towers, since they are not needed to provide an unobstructed view over the entire protected area. The subterranean arrangement also can provide enhanced protection against aerial or projectile attack.
In some embodiments the ultimate heat sink (UHS) is both subterranean and also located inside the protected area within or closely proximate to the nuclear island. For example, in illustrative
Indeed, as disclosed herein, the security plan for the nuclear power facility of
Item (3) is accomplished in the illustrative example of
In this security paradigm, security personnel are disposed in the protected area 30 as mobile patrols and/or ensconced within the reactor building within a short distance from multiple ballistically-protected defensive positions. In some embodiments, there are no guard towers or other stationary guard postings. By employing mobile patrols, and multiple defensive positions, security personnel tend to stay alert as they are frequently moving. The low elevation of the protected area 30 ensures unobstructed view of the entire protected area 30 and isolation zone 34, and the wide physical barrier field of the engagement space 40 ensures that any attempted intrusion will be delayed for an extended period of time.
With continuing reference to
The disclosed nuclear power facility layout advantageously provides increased security for a given operational manpower level. For example, since vehicles entering the parking lot 66 do not need to be searched (as such vehicles remain outside of the blast radius as determined by a blast analysis), personnel who would otherwise be assigned to searching vehicles entering the parking lot can instead be allocated to other tasks relating to security, maintenance, plant inspection, or so forth. Placement of the turbine island outside of the protected area 30 similarly enables more efficient allocation of human resources in the vicinity of the turbine, and/or allows reallocation of some such personnel to the nuclear island.
Another advantage of the disclosed approach is that it facilitates modular construction of the nuclear power facility. Typically, construction cannot begin until final approval for the entire nuclear power facility has been granted by the NRC or other governing regulatory entity. With the improved layout disclosed herein, it may be possible to begin construction on the turbine island and other facilities located outside of the protected area 30 before final approval has been granted for the nuclear island.
The illustrative nuclear power facility of
With reference to
The disclosed improved nuclear power facilities are suitably employed for substantially any type of nuclear power facility. The reduced operating and management costs associated with the disclosed improvements are especially useful in the context of small modular reactor facilities that generate no more than 300 megawatts (electrical).
With reference to
This application has described one or more preferred embodiments. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the application be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
This application claims the benefit of U.S. Provisional Application No. 61/512,644 filed Jul. 28, 2011. This application also claims the benefit of U.S. Provisional Application No. 61/440,545 filed Feb. 8, 2011. U.S. Provisional Application No. 61/512,644 filed Jul. 28, 2011 is incorporated herein by reference in its entirety. U.S. Provisional Application No. 61/440,545 filed Feb. 8, 2011 is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61512644 | Jul 2011 | US | |
61440545 | Feb 2011 | US | |
61512644 | Jul 2011 | US | |
61440545 | Feb 2011 | US |