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 12/15/2025. The amendments to the claims have been entered. Claims 1-5, 7-8, and 11-17 are pending in the application with claims 2, 5, 7-8, 14-15, and 17 withdrawn. Claims 1, 3-4, 11-13, and 16 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 Rejections - 35 USC § 103
Claims 1 and 11 are rejected under 35 U.S.C. 103 as being unpatentable over FR Publication No. 2679062 (“Kawashima”) in view of “Heterogeneous Recycling in Fast Reactors” (“Forget”), US Publication No. 2011/0194667 (“Mariani”), and US Patent No. 5,299,241 (“Suzuki”).
Regarding claims 1 and 11, Kawashima1 (previously cited) (see FIGS. 19, 25a-25c (annotated below)) discloses a core of a fast reactor (1:13-15), the core comprising:
an inner core region (5a) in which a plurality of first fuel assemblies (8) are loaded (10:378-380); and
an outer core region (5b) which surrounds the inner core region and in which a plurality of second fuel assemblies are loaded (10:378-380), wherein
each of the first fuel assemblies of the plurality of first fuel assemblies comprises:
a nuclear fuel material region, the nuclear fuel material region having a lower end and an upper end, comprising:
a nuclear fuel material, comprising a first nuclear fuel material (55), a second material (58), and a third nuclear fuel material (57) (6:218-219, 12:460-469),
a first lower core fuel region in contact with the lower end;
a first upper core fuel region in contact with the upper end; and
a first inner blanket region disposed between the first lower core fuel region and the first upper core fuel region,
a plurality of first fuel rods (80b) comprising the first nuclear fuel material and the third nuclear fuel material (12:460-469); and
a plurality of second fuel rods (80a) comprising the second nuclear fuel material (12:460-469), wherein
in each of the plurality of first fuel rods, a second lower core fuel region is formed within the first lower core fuel region, a second inner blanket region is formed within the first inner blanket region, and a second upper core fuel region is formed within the first upper core fuel region (10:378-398; see 11:446-452),
in each of the plurality of second fuel rods, a third lower core fuel region is formed within the first lower core fuel region, a third inner blanket region is formed within the first inner blanket region, and a third upper core fuel region is formed within the first upper core fuel region (10:378-398; see 11:446-452), and
the first nuclear fuel material is present in each of the second lower core fuel region and the second upper core fuel region of each of the plurality of first fuel rods, does not contain moderating material or minor actinides (herein referred to as “MA”), and contains uranium and plutonium (6:218-219, 12:465-467),
the second material is present in the third inner blanket region of each of the plurality of second fuel rods, does not contain uranium, and comprises moderating material (12:462-465),
the third nuclear fuel material is present in the second inner blanket region of each of the plurality of first fuel rods, does not contain MA, and contains uranium (6:218-219, 12:465-467),
a fourth lower core fuel region, a fourth inner blanket region (56a), and a fourth upper core fuel region are formed in the inner core region in this order from a lower end to an upper end of the inner core region (10:378-386), and
the fourth lower core fuel region is formed within the second lower core fuel region, the fourth inner blanket region is formed within the second inner blanket region, and the fourth upper core fuel region is formed within the second upper core fuel region (10:378-398).
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Kawashima, FIGS. 19, 25a-25c (annotated)
Kawashima does not appear to disclose the second material in the third inner blanket region is a nuclear fuel material containing MA or zirconium. However, as discussed above, Kawashima discloses the second material includes moderating material (12:462-465). Forget (previously cited) is also directed towards a moderating material for a fast reactor (Abstract). Forget teaches the moderating material may be MA-Zr-H, which does not contain uranium (U) and comprises MA and zirconium (Zr) (pp. 9-10). Forget further teaches MA-Zr-H is a suitable moderating material for use in fast reactors and further teaches including MA allows for transmutation of the MA, thereby burning and reducing waste produced from light water nuclear reactors (p. 9). It would have therefore been obvious to a person having ordinary skill in the art before the effective filing date (“POSA”) to use the moderating material taught by Forget (e.g., the MA-Zr-H which does not contain uranium and comprises MA and zirconium) in Kawashima’s fuel assembly for the transmutation benefits thereof. Thus, modification of Kawashima in order to reduce nuclear waste, as suggested by Forget, would have been obvious to a POSA. As discussed above, Kawashima discloses only the third inner blanket region of each of the second fuel rods contains the moderating material (p. 12, ll. 462-465). Therefore, Kawashima, modified to replace Kawashima’s moderating material with the moderating material taught by Forget (e.g., MA-Zr-H), would have resulted in the second nuclear fuel material that is present in the third inner blanket region, does not contain uranium (Kawashima, p. 12, ll. 462-465; Forget, pp. 9-10), and comprises MA and zirconium (Forget, pp. 9-10) as recited in claim 1.
Kawashima does not appear to disclose the first nuclear fuel material and the third nuclear fuel material comprise zirconium. Mariani (previously cited) is similarly directed towards a nuclear fuel material and teaches adding zirconium to nuclear fuel materials such as nuclear fuel materials comprising uranium and plutonium (e.g., Kawashima’s first nuclear fuel material) and nuclear fuel materials comprising uranium (e.g., Kawashima’s third nuclear fuel material). ([0011]-[0012]). Mariani further teaches the zirconium reduces fuel cladding chemical interactions, thereby preventing cladding failure, and further stabilizes the γ-U phase, thereby allowing for more uniform and predictable reactivity ([0009]-[0012], [0030]). It would have therefore been obvious to a POSA to include zirconium in the modified Kawashima’s first and third nuclear fuel materials, as taught by Mariani, for the fuel performance benefits thereof. Thus, further modification of Kawashima in order to enhance safety and improve reactivity, as suggested by Mariani, would have been obvious to a POSA.
Kawashima discloses the first fuel rods and the second fuel rods are loaded in the fuel assemblies, but appears to be silent as to the specific arrangement of the first fuel rods relative to the second fuel rods. However, it was known in the art to separate fuel rods of a first type which does not include MA with fuel rods of a second type which include MA. For example, Suzuki (previously cited) (see FIGS. 1, 22-23) is also directed towards a core (12) of a fast reactor (10) comprising a fuel assembly (110), the fuel assembly comprising first fuel rods (116) which do not contain MA and second fuel rods (115) which contain MA (1:6-12, 13:61-65). Suzuki teaches the first fuel rods are separated from each other by the second fuel rods in a cross section of the fuel assembly (14:16-29). Suzuki further teaches this arrangement of the first fuel rods and the second fuel rods improves mixing of the high-temperature coolant around the second fuel rods and low-temperature coolant around the first fuel rods, thereby enhancing cooling efficiency (14:16-29). It would have therefore been obvious to a POSA to arrange the modified Kawashima’s fuel rods in the manner taught by Suzuki for the safety and cooling benefits thereof. Thus, further modification of Kawashima in order to improve cooling in the fuel assembly, as suggested by Suzuki, would have been obvious to a POSA.
Suzuki further teaches the average enrichment of MA may be 5 wt% (11:1-6), which falls within the claimed range of 3.7 wt% or more and 12.5 wt% or less. Suzuki teaches an MA enrichment that is too high will undesirably increase the effective multiplication factor and a MA enrichment of 5 wt% minimizes excess reactivity (8:62-66, 11:1-17). Additionally, Forget further teaches the average enrichment of MA in a blanket region of the reactor may be 15 wt% (Table 2-9 (p. 16)), which approaches the claimed range of 3.7 wt% or more and 12.5 wt% or less. Forget also teaches varying the MA enrichment in a blanket region and gives examples of blanket materials having MA volume fractions from between 2% to 10% (p. 46: “Concentration of minor actinides will be varied (up to 10% volume)”, “varying the minor actinide volume fraction in the blanket assemblies from 1% to 10%”). In these examples, Forget suggests an average enrichment of MA in the range of 1.5 wt% or more and 7.9 wt% or less2, which overlaps with the claimed range of 3.7 wt% or more and 12.5 wt% or less. Additionally, it would have been obvious to a POSA to have the average enrichment of MA within a range of 3.7 wt% or more and 12.5 wt% or less 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 MA enrichment would be advantageous from a proliferation standpoint (Forget, p. 47), but would also result in reduced core performance (Forget, pp. 47-48) and increased excess reactivity (Suzuki, 8:62-9:6).
Claims 3-4, 12-13, and 16, as best understood, are rejected under 35 U.S.C. 103 as being unpatentable over Kawashima in view of Forget, Mariani, and Suzuki further in view of US Publication No. 2021/0098143 (“Trojer”).
Regarding claim 3, Kawashima in view of Forget, Mariani, and Suzuki teaches the fuel assembly according to claim 1. Kawashima further discloses each of the first nuclear fuel material and the second nuclear fuel material has a solid shape and is disposed in a sealed cladding tube of each of the first fuel rods and each the second fuel rods, respectively (p. 1, ll. 18-19), but does not appear to disclose bond sodium (i.e., liquid metal sodium; see instant specification, p. 17). However, Kawashima discloses the reactor is a sodium-cooled liquid metal fast reactor (p. 1, ll. 13-25). Trojer (previously cited) is also directed towards fuel elements and materials, for example, for a sodium-cooled liquid metal fast reactor ([0231]-[0235], [0242]) and teaches fuel elements for these types of reactors may include bond sodium filled between a nuclear fuel material and a cladding tube ([0242]). Trojer further teaches the bond sodium reduces the temperature of the fuel ([0242]). It would have therefore been obvious to a POSA to include bond sodium, as taught by Trojer, in the modified Kawashima’s fuel rods for the cooling benefits thereof. Thus, further modification of Kawashima in order to improve the thermal properties of the fuel rods, as suggested by Trojer, would have been obvious to a POSA.
Regarding claim 4, Kawashima in view of Forget, Mariani, Suzuki, and Trojer teaches the fuel assembly according to claim 3. Trojer further teaches the nuclear fuel material may be a metal fuel ([0233]). Trojer teaches the metal fuel has a higher heat conductivity and is used in liquid metal fast breeder reactors ([0233]). It would have therefore been obvious to a POSA to include a metal fuel material, as suggested by Trojer, in each of the first nuclear fuel material and the second nuclear fuel material of the modified Kawashima for the predictable advantage of further improving heat transfer.
Regarding claim 12, Kawashima (see FIGS. 19, 25a-25c (annotated above)) discloses a core of a fast reactor (p. 1, ll. 13-15), the core comprising:
an inner core region (5a) in which a plurality of first fuel assemblies (8) are loaded (p. 10, ll. 378-380); and
an outer core region (5b) which surrounds the inner core region and in which a plurality of second fuel assemblies are loaded (p. 378-380), wherein
a fourth lower core fuel region, a fourth inner blanket region (56a), and a fourth upper core fuel region are formed in the inner core region in this order from a lower end to an upper end of the inner core region (p. 10, ll. 378-386), and
the fourth lower core fuel region is formed at a position corresponding to the second lower core fuel region, the fourth inner blanket region is formed at a position corresponding to the second inner blanket region, and the fourth upper core fuel region is formed at a position corresponding to the second upper core fuel region (p. 10, ll. 378-398).
As discussed above, Kawashima, modified to include the MA and zirconium containing material as taught by Forget, the zirconium as taught by Mariani, the fuel rod arrangement taught by Suzuki, and the bond sodium and metallic fuel taught by Trojer, teaches the fuel assemblies according to claim 4. Therefore, Kawashima in view of Forget, Mariani, Suzuki, and Trojer teaches the cores as recited in claim 12.
Regarding claim 13, Kawashima (see FIGS. 19, 25a-25c (annotated above)) discloses a core of a fast reactor (p. 1, ll. 13-15), the core comprising:
an inner core region (5a) in which a plurality of first fuel assemblies (8) are loaded (p. 10, ll. 378-380); and
an outer core region (5b) which surrounds the inner core region and in which a plurality of second fuel assemblies are loaded (p. 378-380), wherein
a fourth lower core fuel region, a fourth inner blanket region (56a), and a fourth upper core fuel region are formed in the inner core region in this order from a lower end to an upper end of the inner core region (p. 10, ll. 378-386), and
the fourth lower core fuel region is formed at a position corresponding to the second lower core fuel region, the fourth inner blanket region is formed at a position corresponding to the second inner blanket region, and the fourth upper core fuel region is formed at a position corresponding to the second upper core fuel region (p. 10, ll. 378-398).
As discussed above, Kawashima, modified to include the MA and zirconium containing material as taught by Forget, the zirconium as taught by Mariani, the fuel rod arrangement taught by Suzuki, and the bond sodium and metallic fuel taught by Trojer, teaches the fuel assemblies according to claim 3. Therefore, Kawashima in view of Forget, Mariani, Suzuki, and Trojer teaches the cores as recited in claim 13.
Regarding claim 16, Kawashima in view of Forget, Mariani, Suzuki, and Trojer teaches the core of the fast reactor according to claim 12. Kawashima further discloses a midpoint of the fourth inner blanket region along a length of the fourth inner blanket region is within a range between a midpoint of the inner core region along a length of the inner core region and a point shifted downward by 5 cm from the midpoint of the inner core region along the length of the inner core region, the midpoint of the fourth inner blanket region is located between a first end and a second end of the fourth inner blanket region, and the midpoint of the inner core region is located between a first end and a second end of the inner core region (FIG. 19).
Response to Arguments
Applicant’s amendments to the claims overcome the prior claim objections and 35 U.S.C. 112(a) and 35 U.S.C. 112(b) rejections.
In response to Applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). Kawashima discloses a core of a fast reactor comprising a fuel assembly having a plurality of first fuel rods (80b) comprising a first nuclear fuel material (55) (which does not contain MA and which comprises uranium and plutonium) and a third nuclear fuel material (57) (which does not contain MA and which comprises uranium), and a plurality of second fuel rods (80a) comprising a second material (58) (which is a moderating material that does not contain uranium) (FIGS. 25a-c, 6:218-219, 12:460-469); Forget establishes that MA-Zr-H may be used as a moderating material in fast reactors (e.g., Kawashima’s reactor) for the predictable advantage of burning and reducing waste produced from light water nuclear reactors (pp. 9-10); Mariani establishes that zirconium may be added to nuclear fuel materials comprising uranium and plutonium (e.g., Kawashima’s first nuclear fuel material 55) or uranium (e.g., Kawashima’s third nuclear fuel material 57) for the predictable advantages of preventing cladding failure and allowing for more uniform and predictable reactivity ([0009]-[0012], [0030]); Suzuki establishes that separating fuel rods of a first type which do not include MA (e.g., the modified Kawashima’s first fuel rods 80b) from fuel rods of a second type which include MA (e.g., the modified Kawashima’s second fuel rods 80a which include Forget’s MA-Zr-H material) provides the predictable advantage of enhancing cooling efficiency (14:16-29). Accordingly, the combination of Kawashima with Forget, Mariani, and Suzuki results in the features as recited in claims 1 and 11.
Applicant further argues “the Office Action alleges that a moderating material 58 of Kawashima corresponds to the claimed second nuclear fuel material” (Remarks, p. 10). However, in the prior Office action and above, Examiner does not state that Kawashima’s moderating material is a second “nuclear fuel” material. Rather, Examiner states that Kawashima “discloses ... a second material (58)”.
Applicant further argues “both the purpose of the application and the fuel structure to achieve this purpose are completely different from Kawashima” (Remarks, p. 10) and “the purpose of Forget is MA transmutation, which differs from the present invention’s purpose of improving core safety through burnup reactivity reduction” (Remarks, p. 11). However, the fact that Applicant has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious. See Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985). Additionally, Applicant's arguments fail to consider the combination of Kawashima’s core with the teachings of Forget, Mariani, and Suzuki. Specifically, as discussed above, the modified Kawashima’s core includes replacing Kawashima’s second material (e.g., Kawashima’s moderating material) with the MA-Zr-H moderating material taught by Forget, including zirconium in Kawashima’s first nuclear fuel material and third nuclear fuel material as taught by Mariani, and arranging the fuel rods in the manner taught by Suzuki. Thus, the modified Kawashima’s core also comprises a first nuclear fuel material (e.g., Kawashima’s material 55 + Mariani’s zirconium), a second nuclear fuel material (e.g., Forget’s MA-Zr-H), and a third nuclear fuel material (e.g., Kawashima’s material 57 + Mariani’s zirconium).
Applicant further argues the skilled artisan would not have been motivated to combine Kawashima and Forget because “[n]ot only do Kawashima and Forget have different fuel rod configurations, but the moderator rods of Kawashima are designed to manipulate neutron flux for reactivity suppression, not for MA transmutation” (Remarks, pp. 11-12). However, obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007). In this case, the rejection states that Forget supplies the required motivation: “Forget further teaches MA-Zr-H is a suitable moderating material for use in fast reactors and further teaches including MA allows for transmutation of the MA, thereby burning and reducing waste produced from light water nuclear reactors (p. 9). It would have therefore been obvious to a person having ordinary skill in the art before the effective filing date (‘POSA’) to use the moderating material taught by Forget (e.g., including MA and zirconium) in Kawashima’s fuel assembly for the transmutation benefits thereof. Thus, modification of Kawashima in order to reduce nuclear waste, as suggested by Forget, would have been obvious to a POSA”.
Applicant further argues “[t]here is no suggestion anywhere in Kawashima in including zirconium.... Consequently, one of ordinary skill in the art would have no motivation to combine Mariani and Kawashima, and indeed adding zirconium to the fuel of Kawashima would impact the suppression of core reactivity of Kawashima. Moreover, Kawashima lacks any discussion of preventing cladding failure” (Remarks, p. 12). Examiner first notes, Kawashima is not used to teach including zirconium in the “first nuclear fuel material”. Mariani is. Additionally, obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007). In this case, the rejection states that Mariani supplies the required motivation: “Mariani further teaches the zirconium reduces fuel cladding chemical interactions, thereby preventing cladding failure, and further stabilizes the γ-U phase, thereby allowing for more uniform and predictable reactivity ([0009]-[0012], [0030]). It would have therefore been obvious to a POSA to include zirconium in the modified Kawashima’s first and third nuclear fuel materials, as taught by Mariani, for the fuel performance benefits thereof. Thus, further modification of Kawashima in order to enhance safety and improve reactivity, as suggested by Mariani, would have been obvious to a POSA”. Further, there does not appear to be any detail or explicit reasoning provided in support of Applicant’s assertion that “adding zirconium to the fuel of Kawashima would impact the suppression of core reactivity of Kawashima”. Applicant fails to support the assertion that the inclusion of zirconium in Kawashima’s first and third nuclear fuel materials, as taught by Mariani, would render the core of Kawashima “unsatisfactory for its intended purpose” with any factual underpinning whatsoever. Moreover, there is no portion of Kawashima that would prevent a skilled artisan from adding zirconium to Kawashima’s fuel materials, as taught by Mariani.
Applicant further requested that, “[t]o the extent that the Examiner relies on personal knowledge in contending that a POSA would have known that the fuel assembly of Kawashima could be improved by the disclosure of Mariani”, Examiner provide an affidavit or declaration setting forth specific factual statements and explanation to support the finding (Remarks, pp. 12-13). Examiner has not relied on any personal knowledge, but rather on teachings, suggestions, or motivations found in the references themselves. As stated above and in the prior Office action, Mariani supplies the required teaching, suggestion, or motivation for including zirconium in the modified Kawashima’s first and third nuclear fuel materials. Specifically, for example, Mariani teaches: “Zirconium is added as an alloy component to help reduce FCCI, as zirconium is known to form a thin rind on the peripheral fuel surface that impedes contact between cladding and other fuel components. Zirconium is also added as an alloy component because it lowers the onset temperature for γ-U formation (otherwise reported as stabilizing the γ-U phase). The γ-U phase is desirable in comparison to other uranium phases because the crystal lattice is cubic. Under the influence of process heat of fission, the cubic γ-U must expand isotropically.... Anisotropic expansion is very undesirable because the nuclear reactivity of the fuel alloy becomes less predictable, resulting in reduced fuel lifetime and burnup” ([0012]).
Applicant’s argument that Examiner has applied hindsight reasoning is unpersuasive. It must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper. See In re McLaughlin, 443 F.2d 1392, 170 USPQ 209 (CCPA 1971). Obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007).
Conclusion
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 7:30AM-5:30PM ET. Supervisor Jack Keith (SPE) can be reached at (571) 272-6878.
/JINNEY KIL/Examiner, Art Unit 3646
1Citations to Kawashima refer to the machine translation provided with the PTO-892 dated 09/18/2023.
2 See calculations and explanation in Non-Final Rejection dated 09/15/2025, p. 13