DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Status of Claims
A reply was filed on 02/19/2026. The amendments to the claims have been entered. Claims 1, 3-6, 9-11, 13-19, and 21-39 are pending in the application with claims 19 and 21-39 withdrawn. Claims 1, 3-6, 9-11, and 13-18 are examined herein.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claim Objections
Claims 9-11 are objected to because of the following informalities: each of claims 9-11 should be amended to depend from claim 1. Appropriate correction is required.
Claim Rejections - 35 USC § 103
Claims 1, 3, 5-6, 9-11, 13, and 16-18 are rejected under 35 U.S.C. 103 as being unpatentable over US Publication No. 2015/0357056 (“Shayer”) in view of US Patent No. 3,409,502 (“Barker”), “Gamma and Neutron Shielding Behavior of Spark Plasma Sintered Boron Carbide-Tungsten Based Composites” (“Ozer”), and US Patent No. 4,180,951 (“Francioni”).
Regarding claim 1, Shayer (previously cited) (see FIGS. 1A-1B, 6A-6B) discloses a nuclear reactor system (10) comprising:
a pressure vessel (14) including an interior wall ([0042]);
a nuclear reactor core (12) located within the interior wall of the pressure vessel ([0042]), wherein the nuclear reactor core includes a fuel element array (18) of a plurality of fuel elements (21) and at least one moderator element (“moderators”) (FIG. 2, [0043], [0058]);
a reflector (16, 46) located inside the pressure vessel that includes a plurality of reflector blocks laterally surrounding the plurality of fuel elements and the at least one moderator element ([0042], [0067]); and
a plurality of control drums (20) ([0066]).
Shayer does not appear to disclose an in-vessel shield as recited in claim 1. However, Shayer discloses the reactor system may comprise a shield surrounding the reactor core ([0043]) and/or other shielding structures ([0045]). Barker (previously cited) (see FIGS. 2A-2B) is similarly directed towards a nuclear reactor system comprising a pressure vessel (35, 36, 37) including an interior wall (37) (4:32-34). Barker teaches the system further comprises an in-vessel shield (44) located on the interior wall of the pressure vessel, wherein the in-vessel shield is disposed in direct contact with the interior wall (4:52-58). Barker further teaches the in-vessel shield provides the advantages of shielding the vessel from damage by neutrons (4:52-58). It would have therefore been obvious to a person having ordinary skill in the art before the effective filing date (“POSA”) to include an in-vessel shield as taught by Barker and as suggested by Shayer for the benefits thereof. Thus, modification of Shayer in order to protect the vessel from neutron damage, as suggested by Barker and Shayer, would have been obvious to a POSA.
Barker teaches the in-vessel shield includes steel (4:52-58) rather than the composited ceramic material and tungsten, iron, nickel, or copper material recited in claim 1. Ozer (previously cited) is similarly directed towards shielding materials for nuclear applications (Title, p. 449: “B4C based materials are commonly used in nuclear applications”). Ozer teaches the shielding material may be formed of two or more neutron absorbing materials, including a first material and a second material, the first material including a composited ceramic material (e.g., B4C) and the second material including tungsten (W) (p. 450: “B4C based composites with 5, 10 and 15 vol. % W addition”). Ozer further teaches this shielding material is suitable as a neutron and gamma shielding material and has a low density and high hardness, melting point, and thermal neutron capture cross-section (p. 449: “Boron carbide (B4C) is a suitable material for nuclear technology because it has very high hardness, high melting point, low density, and especially high thermal neutron capture cross-section”; p. 455: “Increasing W content in B4C improves gamma shielding properties”). It would have therefore been obvious to a POSA to have the modified Shayer’s in-vessel shield formed of the materials taught by Ozer for the benefits thereof. Thus, further modification of Shayer in order to enhance neutron and gamma shielding, as suggested by Ozer, would have been obvious to a POSA. Additionally, it would have been obvious to a POSA to use Ozer’s neutron absorbing materials for the material of the modified Shayer’s in-vessel shield since it has been held to be within the general skill of a worker in the art to select known material on the basis of its suitability for the intended use as a matter of obvious design choice. See In re Leshin, 125 USPQ 416.
Barker teaches the in-vessel shield is in direct contact with the interior wall of the pressure vessel (FIGS. 2A-2B), but appears to teach the in-vessel shield is formed as a single unit, rather than as a plurality of in-vessel shield tiles. However, it was known in the art to form in-vessel shields as a plurality of in-vessel shield tiles. For example, Francioni (newly cited) (see FIGS. 1-2) is similarly directed towards a nuclear reactor system comprising a shield (“biological shield”) (2:39-44). Francioni teaches the shield is formed as a plurality of shield tiles (3), all sides of at least one of the shield tiles being joined to adjacent shield tiles (1:51-2:4, 2:39-66). Francioni further teaches forming the shield as a plurality of shield tiles provides the advantages of allowing selective removal and disposal of different portions of the shield (1:51-2:4, 7:15-21). It would have therefore been obvious to a POSA to form the modified Shayer’s in-vessel shield as a plurality of in-vessel shield tiles, as taught by Francioni, for the benefits thereof. Thus, further modification of Shayer in order to allow for easier removal of shield structures, as suggested by Francioni, would have been obvious to a POSA. Additionally, it would have been obvious to a POSA to form the in-vessel shield of the modified Shayer’s system as a plurality of in-vessel shield tiles, as taught by Francioni, since it has been held that constituting a formerly integral structure in various elements involves only routine skill in the art. Nerwin v. Erlichman, 168 USPQ 177, 179. In re Dulberg, 289 F.2d 522, 523, 129 USPQ 348, 349 (CCPA 1961). Such modification would have provided the predictable advantage of allowing for the replacement of part of the shield, without needing to replace the entire shield.
Regarding claim 3, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Ozer teaches the composited ceramic material includes boron carbide (B4C) (Abstract). Thus, Shayer, modified to include the in-vessel shield as taught by Barker formed of the neutron absorbing materials taught by Ozer and as a plurality of in-vessel shield tiles as taught by Francioni, would have resulted in the features of claim 3.
Regarding claim 5, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Ozer teaches the composited ceramic material includes boron carbide (B4C), but appears to be silent as to the isotopic composition of the boron. Therefore, the skilled artisan would reasonably expect the boron to be naturally occurring boron1, which includes isotopes of 10B. Thus, Shayer, modified to include the in-vessel shield as taught by Barker formed of the neutron absorbing materials taught by Ozer and as a plurality of in-vessel shield tiles as taught by Francioni, would have resulted in the features of claim 5. Nevertheless, if necessary, Shayer discloses boron-10 is the primary contributor to the neutron absorption cross-section of boron and, further, is depleted over time, thus providing the advantage of improving backscattering of neutrons into the nuclear reactor core and fuel utilization ([0016], [0077]-[0078], [0093], [0103]). It would have therefore been obvious to a POSA to have the boron carbide of the modified Shayer’s composited ceramic material include boron-10 for the predictable advantage of enhancing neutron shielding, as suggested by Shayer. Additionally, it would have been obvious to a POSA to use boron-10 carbide for the material of the composited ceramic material since it has been held to be within the general skill of a worker in the art to select known material on the basis of its suitability for the intended use as a matter of obvious design choice. See In re Leshin, 125 USPQ 416.
Regarding claim 6, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Ozer teaches the composited ceramic material includes a plurality of composited ceramic particles with an average particle diameter of 0.7 µm (i.e., 0.7 microns or 700 nm) (p. 450: “B4C powders ... with an average particle size of 0.7 µm”), which falls within the claimed range of greater than or equal to approximately2 80 nanometers and less than or equal to approximately 100 microns. Thus, Shayer, modified to include the in-vessel shield as taught by Barker formed of the neutron absorbing materials taught by Ozer and as a plurality of in-vessel shield tiles as taught by Francioni, would have resulted in the features of claim 6.
Regarding claim 9, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Francioni teaches all or a subset of the plurality of in-vessel shield tiles are a curved polyhedron shape (FIGS. 1-2, 2:39-44). Thus, Shayer, modified to include the in-vessel shield as taught by Barker formed of the neutron absorbing materials taught by Ozer and as a plurality of in-vessel shield tiles as taught by Francioni, would have resulted in the features of claim 9.
Regarding claim 10, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Francioni teaches the plurality of in-vessel shield tiles include a base shape and the in-vessel shield is formed by a geometric pattern of the plurality of in-vessel shield tiles (FIGS. 1-2, 2:39-66). Thus, Shayer, modified to include the in-vessel shield as taught by Barker formed of the neutron absorbing materials taught by Ozer and as a plurality of in-vessel shield tiles as taught by Francioni, would have resulted in the features of claim 10.
Regarding claim 11, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Shayer discloses the interior wall comprises a continuous surface (FIGS. 1A-1B, 6A-6B). Ozer teaches the in-vessel shield lines the continuous surface of the interior wall (FIGS. 2A-2B). Francioni teaches the plurality of in-vessel shield tiles are joined to collectively form the in-vessel shield (FIGS. 1-2, 2:39-66). Thus, Shayer, modified to include the in-vessel shield as taught by Barker formed of the neutron absorbing materials taught by Ozer and as a plurality of in-vessel shield tiles as taught by Francioni, would have resulted in the features of claim 11.
Regarding claim 13, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Thickness, diffusion coefficient, macroscopic absorption cross section, and diffusion length are all properties of a material3,4. In other words, any physical structure would inherently have a thickness, diffusion coefficient, macroscopic absorption cross section, and diffusion length. Further, the diffusion length of a three-dimensional structure is determined based on the thickness, diffusion coefficients, and macroscopic cross sections of each of the materials forming the structure. Therefore, as the modified Shayer’s reflector block and in-vessel shield are three-dimensional structures, the modified Shayer’s reflector block and in-vessel shield each have a thickness, diffusion coefficient, macroscopic absorption cross section, and diffusion length and the combination of the modified Shayer’s reflector block and in-vessel shield has a combined diffusion length which is based on the thickness, diffusion coefficients, and macroscopic cross sections of the individual materials.
The modified Shayer appears to be silent as to the thickness of the reflector and the in-vessel shield relative to the combined diffusion length. However, Shayer discloses the purpose of the reflectors is to minimize neutron leakage and maintain a desired criticality in the nuclear reactor core ([0071]) and the purpose of the in-vessel shield is to provide containment ([0045]). Shayer further discloses the size of the nuclear reactor system depends on at least the reflector thickness ([0046], [0073]). It would have been obvious to a POSA to have a combined thickness of the reflector and the in-vessel shield that is less than double the combined diffusion length since it has been held that, where the general conditions of a claim are disclosed in the prior art, discovering an optimum or workable range involves only routine skill in the art. A POSA would have been aware that increasing the combined thickness would reduce the amount of neutrons escaping the nuclear reactor core, but would also increase the size of the nuclear reactor system, while decreasing the combined thickness would increase the amount of neutrons escaping the nuclear reactor core, but would reduce the size of the system. The skilled artisan would have been capable of varying the combined thickness of the modified Shayer’s reflector and in-vessel shield in order to achieve a desired neutron containment and reactor size.
Regarding claim 16, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Shayer discloses the nuclear reactor system includes the plurality of control drums, wherein the control drums are interspersed or disposed within the reflector (FIGS. 6A-6B).
Regarding claim 17, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Shayer discloses the nuclear reactor system includes a gas-cooled nuclear reactor ([0057]).
Regarding claim 18, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Shayer discloses a coolant that flows through the plurality of fuel elements, wherein the coolant includes helium ([0057]).
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Shayer in view of Barker, Ozer, and Francioni, further in view of “Progress in Pressureless Sintering of Boron Carbide Ceramics – A Review” (“Zhang”).
Regarding claim 4, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 3, but does not appear to teach the composited ceramic material further includes aluminum oxide or silicon carbide. Zhang (previously cited) is similarly directed towards a composited ceramic material comprising boron carbide (B4C) which may be used as a neutron absorbing material in nuclear reactors (p. 222: “Boron carbide (B4C) ceramics has many outstanding performance, such as ... high neutron absorption cross section.... B4C ceramics can be used as light-weight ceramic armour, high temperature thermocouples, neutron absorber, reactor control rods in nuclear power engineering”). Zhang teaches the composited ceramic material further includes aluminum oxide (Al2O3) (p. 228: “the addition of Al2O3 enhanced the densification of B4C ceramics”) or silicon carbide (SiC) (p. 226: “Silicon with light weight is a metalloid type additive which can promote the densification of B-4C ceramics effectively.... [T]he main crystal phase of the ceramics is B4C and SiC”; p. 233: “dense B4C based composites by sintering B4C with SiC and Al”). Zhang further teaches the addition of Al2O3 provides the advantages of promoting densification of the composited ceramic material, improving the strength, toughness, hardness, and elastic modulus of the composited ceramic material, and reducing the porosity of the composited ceramic material (p. 228: “adding Al2O3 into B4C ceramics not only can increase relative density of the ceramics but also can improve flexural strength, fracture toughness, hardness and elastic modulus”, “Al2O3 can provide liquid phase diffusion and pinning effects for B4C sintering, and the sintering additive can not only hinder the abnormal growth of B4C grains but also significantly reduce the porosity of the ceramics”) and the addition of SiC provides the advantage of promoting densification and improving oxidation resistance (p. 226: “Silicon ... can promote the densification of B4C ceramics effectively”; p. 233: “B4C can be able to sinter by adding one or more carbides, such as silicon carbide”, “The B4C ceramics containing SiC can also improve its oxidation resistance”). It would have therefore been obvious to a POSA to include Al2O3 or SiC in the modified Shayer’s composited ceramic material, as taught by Zhang, for the performance benefits thereof. Thus, further modification of Shayer in order to increase the density of the composited ceramic material and improve the mechanical performance of the composited ceramic material, as suggested by Zhang, would have been obvious to a POSA.
Claims 14-15 are rejected under 35 U.S.C. 103 as being unpatentable over Shayer in view of Barker, Ozer, and Francioni, further in view of US Publication No. 2021/0174976 (“Filippone”).
Regarding claim 14, Shayer in view of Barker, Ozer, and Francioni teaches the nuclear reactor system of claim 1. Shayer discloses each of the fuel elements includes a nuclear fuel (22, 28) (FIG. 2, [0054]), the nuclear fuel including a fuel compact comprised of coated fuel particles (30) embedded inside a matrix (FIG. 3, [0059]-[0061]). Shayer discloses the matrix may include a material such as beryllium oxide or graphite ([0047], [0059]), but does not appear to disclose the matrix includes one of the materials recited in claim 14. Filippone (previously cited) is also directed towards a nuclear reactor system ([0002]) comprising a nuclear reactor core (1) and teaches the core includes a plurality of fuel elements (20) and at least one moderator element (3, 4, 6, 32) ([0060], [0062], [0067]-[0068], [0093], [0115], [0118]). Filippone teaches each of the fuel elements comprises a nuclear fuel which includes a fuel compact comprised of coated fuel particles (20a) embedded inside a silicon carbide matrix (21) (FIGS. 2, 12, [0093], [0101]). Filippone further teaches silicon carbide is a suitable material for the nuclear fuel and provides the advantage of being a pressure resistant material ([0093]). It would have therefore been obvious to a POSA to use replace the modified Shayer’s beryllium oxide or graphite matrix material with Filippone’s silicon carbide material for the safety benefits thereof. Thus, further modification of Shayer in order to provide a pressure resistant matrix material, as suggested by Filippone, would have been obvious to a POSA. Additionally, it would have been obvious to a POSA to use silicon carbide for the material of the modified Shayer’s matrix material since it has been held to be within the general skill of a worker in the art to select known material on the basis of its suitability for the intended use as a matter of obvious design choice. See In re Leshin, 125 USPQ 416.
Regarding claim 15, Shayer in view of Barker, Ozer, and Filippone teaches the nuclear reactor system of claim 14. Shayer discloses the coated fuel particles includes tristructural-isotropic (TRISO) fuel particles (FIG. 3, [0047], [0059]-[0061]).
Response to Arguments
Applicant’s amendments to the claims overcome the prior 35 U.S.C. 112(b) rejection.
Applicant’s arguments regarding the prior art rejections have been fully considered, but are directed towards newly added and/or amended claim language and are therefore addressed in the rejections above.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. Prosecution on the merits is closed. See MPEP 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any extension fee pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the date of this final action.
RCE Eligibility
Since prosecution is closed, this application is now eligible for a request for continued examination (RCE) under 37 CFR 1.114. Filing an RCE helps to ensure entry of an amendment to the claims, specification, and/or drawings.
Interview Information
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, Applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
Contact Information
Examiner Jinney Kil can be reached at (571) 272-3191, on Monday-Thursday from 8:30AM-6:30PM ET. Supervisor Jack Keith (SPE) can be reached at (571) 272-6878.
/JINNEY KIL/Examiner, Art Unit 3646
1 https://en.wikipedia.org/wiki/Isotopes_of_boron
2 The term “approximately” is being interpreted in view of the definition provided in the specification as meaning “up to ± 10% from the stated amount” ([0027])
3 https://www.nuclear.lu.se/fileadmin/nuclear/Undervisning/Reaktorfysik/Reactor_Physics_tutorials_2013.pdf
4 https://www.nuclear-power.com/nuclear-power/reactor-physics/neutron-diffusion-theory/diffusion-length/