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 .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Terminal Disclaimer
As previously acknowledged, the terminal disclaimer filed on 23 October 2025 disclaiming the terminal portion of any patent granted on this application which would extend beyond the expiration date of US Pat. No. 11,450,442 has been reviewed and is accepted. The terminal disclaimer has been recorded.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 28 February 2026 has been entered.
Election/Restrictions
Applicant's traversal of the Restriction requirement in the reply filed on 28 February 2026 is acknowledged. The traversal is on the ground(s) that “claim 32 is parallel to claim 1, and merely claims a system for performing the method of claim 1.” This is not found persuasive because such an argument does not distinctly and specifically point out any supposed errors in the analysis set forth by Examiner in the action mailed 9 December 2025. The requirement is still deemed proper and is therefore made FINAL.
Claim 32 is withdrawn from further consideration pursuant to 37 CFR 1.142(b), as being drawn to a nonelected invention, there being no allowable generic or linking claim. Applicant timely traversed the restriction (election) requirement in the reply filed on 28 December 2026.
Claim Amendments
Applicant’s amendments to the claims filed 28 February 2026 have been entered and considered for this action. These amendments overcome the prior claim objections, which are withdrawn. Claim rejections under 35 USC § 112(a) and 112(b) remain, as set forth below.
It is noted that the claim status identifier on claim 7 reads “Currently Amended”, however no current amendments are indicated in the claim. This is therefore interpreted as an inadvertent error that is supposed to read “Previously Presented.”
It is noted that Applicant has significantly amended a large portion of the claims. While Applicant asserts that these amendments are fully supported by the original specification, Applicant has not pointed to specific support for any of the changes (see MPEP 713.02). Examiner has not found support for all amendments, as noted below.
Claim Interpretation
Applicant’s discussion of epithermal ranges, pages 16-17 of the reply filed 28 February 2026 is acknowledged.
However, the inclusion of the terms “strong resonance” and “low epithermal energy” themselves raise issue of indefiniteness, as analyzed below. While Applicant points to [00236] to support an interpretation of “near 1 eV”, it would be improper to import a limitation from a single disclosed embodiment into a claim when the claim otherwise does not require it.
As previously set forth, the range of neutron energies that constitute “an epithermal range” is not defined in the specification, and what is considered the upper end of this range varies widely in the art: values cited in the prior range from 10 keV (Shim et al. Applied Radiation and Isotopes, 208 (2024) 111298, p. 1, col. 2, ¶ 1) to 100 keV (Jovanovic; p. 21, column 1, ¶ 6) and up to 1 MeV (Neutron Generators for Analytical Purposes; IAEA; p. 98, ¶ 2). The broadest reasonable interpretation standard dictates that an epithermal range will be interpreted as encompassing from ~0.5 eV up to 1 MeV. What constitutes the “low” portion of this range is indefinite, as set forth below.
Several of the claims recite the phrase “at least a portion of the uranium and the transuranic elements”. In all cases this is interpreted as requiring at least a portion of the uranium, at least a portion of the transuranic elements, or a combination thereof. This is the broadest reasonable interpretation of the claim, and it is distinct from a narrower interpretation that would require at least a portion of the uranium and at least a portion of the transuranic elements.
Such an interpretation is also consistent with claim 9 being further limiting of claim 1.
Claim 4 has been amended as follows: “recovering the uranium isotope 238 (238U) product stream and conditioning the uranium isotope 238 (238U) for commercial distribution as a bulk nuclear material
It is noted that Applicant has not pointed out where the new limitations are supported in the original disclosure, nor does there to be a written description for the new limitations, unless they are interpreted as merely a re-wording of the original claim.
Therefore, the act of conditioning for commercial distribution is merely interpreted as encompassing productizing the product stream, with the possible addition of any steps that may have been obvious to one of ordinary skill in the art in order to do so. Therefore, any teaching of productizing the uranium stream, as previously examined, will also be considered as meeting the limitations of the instant claim, or being an obvious variants thereof.
Any narrower interpretation of this claim would necessitate a rejection under 35 USC § 112(a) as lacking written description.
Claim Objections
Claims 1 and 18 are objected to because of the following informalities:
The preamble to claim 1 recites “…for forming a nanofuel…” but the method step (c) actually recite a process step of forming the nanofuel; the preamble should therefore be amended to read “…[[for]] and forming a nanofuel…”.
Claim 18, line 5 uses the word “monitor” when it should instead recite “moderator.”
Appropriate correction is required.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 5-6, 12, and 20 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 5 has been amended to require “incorporating said at least a portion of the uranium and transuranic elements into the molecular mixture at least one or more of a solid particulate form dispersed withing the molecular mixture; a dissolved liquid from forming a homogenous solution; of a gaseous form.” There is a distinct difference between simply providing the elements in a solid form, a liquid form, or a gaseous form, as required by the original claim and the further limitations of the amended claim. Applicant has not pointed out where the amended claim is supported, nor does there appear to be a written description of the new claim limitations in the application as filed. Accordingly, the amended claim is rejected. See MPEP 2163.04(I).
Claim 6 depends upon claim 5 and places further limits on the incorporating the uranium and the transuranic elements into the molecular mixture in said solid particulate form. Again, Applicant has not pointed out where the amended claim is supported, nor does there appear to be a written description of the new claim limitations in the application as filed. Accordingly, the amended claim is rejected. See MPEP 2163.04(I).
Amended claim 12 recites upper limits on the purity of the plutonium in the transuranic elements stream, but no such limits on purity are discussed in the as filed specification. Applicant cites Table IV as allegedly providing support for the new limitation, but said table only shows one particular embodiment and in no way covers the entire claimed range of less than 99.8%. It is also not clear that the data in Table IV are the result of a separation meeting the limitations of claim 1.
Claim 20 has been amended to require “incorporating the transuranic elements into the molecular mixture as a plasma form.” This limitations is distinct from the originally filed disclosure which only envisions “providing the transuranic elements in a plasma form.” There is a distinct difference between simply providing the elements in a plasma form and the incorporating the elements into a molecular mixture as a plasma form as required by the amended claim. Applicant has not pointed out where the amended claim is supported, nor does there appear to be a written description of the claim limitation “incorporating into a mixture as a plasma form” in the application as filed. Accordingly, the amended claim is rejected. See MPEP 2163.04(I).
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claims 1-13 and 15-31 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 1 recites the limitation “at least one nuclide having a strong resonance neutron absorption cross-section within a low epithermal energy domain. The terms “strong resonance neutron absorption” and “low epithermal energy domain” are relative terms which render the claim indefinite. The terms “strong resonance neutron absorption cross-section” and “low epithermal range” are not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. It is therefore unclear what passive agents meet the limitations of the claim, and the claim is indefinite.
Claims 2-13 and 15-31 depend upon claim 1 without resolving the indefiniteness and are likewise rejected.
Claim 12 is rejected as being indefinite as it recites a limitation requiring “fewer processing steps than the PUREX solvent extraction process….” However, it is unclear how many processing steps this actually is, or even what constitutes a single “step”, and therefore the metes and the bounds of the claim are unclear.
Claim Rejections – 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-11, 13-14, 16-19, 21-22, 25, 29, and 31 are rejected under 35 U.S.C. 103 as being unpatentable over Amamoto et al. (US 7,208,129 B2; hereinafter “Amamoto”) in view of Dugan (“The Nuclear Piston Engine and Pulsed Gaseous Core Reactor Power Systems,” PhD Thesis, University of Florida, 1976), and with respect to claims 3, 13, and 14, as evidenced by the IAEA Report on Management of Reprocessed Uranium (IAEA-TECDOC-1529, February 2007; hereinafter “ IAEA”).
Regarding claim 1, Amamoto teaches a method of obtaining uranium and transuranic elements from spent nuclear fuel comprising:
(a) receiving spent nuclear fuel (Figure 2 top);
(b) separating the uranium and the transuranic elements having atomic numbers 93-118 from the spent nuclear fuel into at least one product stream
(Pu-Cm, Z=94-96, Fig. 2, bottom).
Amamoto does not teach incorporating at least a portion of the uranium and transuranic elements into a molecular mixture forming the nanofuel or forming a temperature-dependent neutron sink that increases as nanofuel temperature increases.
However, Dugan teaches a nuclear piston engine consisting of a pulsed, gaseous core reactor that operates on a thermodynamic cycle similar to the internal combustion engine with its primary working fluid and fuel being a mixture of enriched uranium hexafluoride, UF6, and helium gas, He, a moderator (p. 1, ¶ 1).
Enriched UF6 will contain both the U-235 and U-238 isotopes, where 235UF6 is a fissile fuel. Dugan also teaches that 238U shows increased neutron absorption with increased fuel temperature at 6.67 eV, which falls in the low portion of the epithermal range (p. 260, ¶ 2; see also Claim Interpretation above). Therefore, 238UF6 can be considered a passive agent comprising a nuclide having a strong resonance neutron absorption cross-section within a low epithermal range.
Helium is a moderator which will inherently have the property of being effective to thermalize a neutron population within a thermal energy domain and to absorb a fission fragment kinetic energy.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate at least a portion of the uranium and transuranic elements from the method of Amamoto into a molecular mixture comprised of a fissile fuel comprising 235UF6 which is capable of undergoing neutron induced fission, a moderator comprising helium which is effective to thermalize a neutron population within a thermal energy domain and to absorb a fission fragment energy and a passive agent comprising 238UF6 which has a strong resonance neutron absorption cross-section within a low epithermal energy domain.
One of ordinary skill in the art would have been motivated to incorporate the at least a portion of the uranium and transuranic elements into such a molecular mixture forming the nanofuel because Dugan teaches that a molecular mixture formed with these component can serve as nanofuels in nanofuel engines and that such nanofuel-driven nanofuel engines have high efficiencies (p. xxxviii, ¶ 3) while providing significant savings in fossil fuels (Dugan, p. 3, paragraph 4).
Dugan additionally teaches that an 80% enriched fuel mixture has a negative temperature coefficient of reactivity (coefficients for 80% enriched UF6 were small and negative; p. 346) and that negative temperature coefficients of reactivity are obviously a favorable situation from a safety control standpoint (p. 346, ¶ 1). Dugan further teaches that a moderator and the level of U-235 enrichment in the fuel can contribute to the temperature coefficient of reactivity (p. 346-p. 347).
Because Dugan teaches nanofuel molecular mixture comprised of the same basic components as recited in the claim, it is concluded that the interactions between the neutrons thermalized by the moderator and the passive agent present within the mixture will also be the same, and will therefore form a temperature-dependent neutron sink that increases as nanofuel temperature increases, thereby contributing to the negative coefficient of reactivity that Dugan teaches is advantageous as a safety and control standpoint.
It is further noted that Dugan also teaches that use of Pu fuels in nanofuel engines would be desirable (p. 377, paragraph 3) and that it is the Pu-239 isotope that is analogous to the U-235 used in his original work (p. 9 and 10). Additionally, the courts have held "[i]t is prima facie obvious to combine two compositions each of which is taught by the prior art to be useful for the same purpose, in order to form a third composition to be used for the very same purpose.... [T]he idea of combining them flows logically from their having been individually taught in the prior art." In re Kerkhoven, 626 F.2d 846, 850, 205 USPQ 1069, 1072 (CCPA 1980). MPEP 2144.06(I). Therefore, even if the phrase “at least apportion of the uranium and the transuranic elements” were interpreted as requiring the presence of both uranium and some of the transuranic elements, this combination would also have been obvious because Dugan teaches that both uranium and plutonium can serve as fuels, it would therefore have been obvious to provide them both for a nanofuel.
Regarding claim 2, modified Amamoto teaches the method of claim 1, where Amamoto teaches the receiving a spent oxide fuel comprising uranium and plutonium (column 1, lines 10-12). One of ordinary skill in the art would have understood that such a spent oxide fuel would have been spent nuclear waste from a reactor source, thereby meeting the limitations of claim 2.
Regarding claim 3, modified Amamoto teaches the method of claim 1, where Amamoto also teaches separating the spent nuclear fuel into at least one discrete product stream comprising a uranium product stream comprising uranium isotope 238 as a predominant isotope (UF-6; uranium in spent fuel is predominantly uranium 238; IAEA, Fig. 8).
Regarding claim 4, modified Amamoto teaches the method of claim 3, where Amamoto also teaches recovering the predominantly uranium isotope 238 product stream and producing a raw material for uranium enrichment (column 4, lines 22-23).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to first condition said product stream for commercial distribution as a bulk nuclear material. One of ordinary skill in the art would have been motivated to do so in order to enable its use as a raw material for uranium enrichment by others.
Regarding claim 5, modified Amamoto teaches the method of claim 1, where Amamoto teaches providing the uranium and transuranic elements in a gaseous form (UF6(gas) and PuF6(gas); col. 5, lines 15-17) and where Dugan teaches using gaseous UF6 (p. 1, ¶ 1) in the molecular mixture nanofuel.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate at least a portion of the uranium and transuranic elements into the molecular mixture in a gaseous form. One of ordinary skill in the art would have been motivated to do incorporate them in a gaseous form because doing so requires fewer chemical transformations.
Regarding claim 6, modified Amamoto teaches the method of claim 5 by incorporating the uranium and transuranic elements in a gaseous form. Claim 6 provides no further limitations upon claim 5 in this situation, and therefore modified Amamoto teaches all the required limitations of claim 6.
Regarding claim 7, modified Amamoto teaches the method of claim 1, where Amamoto also teaches separating without isotope separation, as no steps that would afford isotope separation are included in their method.
Regarding claim 8, modified Amamoto teaches the method of claim 1, where Dugan also teaches providing the nanofuel for use in a nanofuel engine.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to provide the nanofuel produced by the method of claim 1 into a nanofuel engine, as taught by Dugan. One of ordinary skill in the art would have been motivated to do so in order to use the nanofuel engine taught by Dugan to produce energy.
Regarding claim 9, modified Amamoto teaches the method of claim 1, where Dugan teaches combining the uranium with a moderator (helium; p. 1, ¶ 1) to obtain a nanofuel. Dugan further teaches that use of Pu fuels in nanofuel engines would be desirable (p. 377, paragraph 3) and that it is the Pu-239 isotope that is analogous to the U-235 used in his original work (p. 9 and 10).
Therefore it would have been obvious to mix both uranium and transuranic elements (Pu) with a moderator to obtain a nanofuel because it is prima facie obvious to combine two compositions each of which is taught by the prior art to be useful for the same purpose, in order to form a third composition to be used for the very same purpose.... [T]he idea of combining them flows logically from their having been individually taught in the prior art." In re Kerkhoven, 626 F.2d 846, 850, 205 USPQ 1069, 1072 (CCPA 1980). MPEP 2144.06(I).
Regarding claim 10 and 11, modified Amamoto teaches the method of claim 9, and Dugan further teaches using their nanofuel mixture in a nanofuel engine (p. 1, ¶ 1), which would require loading the nanofuel comprised of the uranium, the transuranic elements, and the moderator into the nanofuel engine.
Regarding claims 13 and 14, modified Amamoto teaches the method of claim 9 where Dugan teaches using Pu in the nanofuel, and where Amamoto teaches the production of PuF6, which when derived from spent nuclear fuel will contain both 239PuF6 (a fissile fuel) and 240PuF6 (a passive agent), as evidenced by IAEA (Table 2 and 3).
Regarding claim 16, modified Amamoto teaches the method of claim 9, where Amamoto also teaches converting the uranium and the transuranic elements into a gas form (mixture of UF6 and PuF6 is vaporized and provided; column 6, lines 13-14) and where Dugan teaches mixing the uranium and the transuranic elements in gas form with a moderator (helium; p. 1) to obtain the nanofuel.
Regarding claim 17, modified Amamoto teaches the method of claim 16, where Amamoto also teaches loading the uranium and the transuranic elements in a tetrafluoride form into a fluorination reactor and converting the uranium and the transuranic elements in said tetrafluoride form to the uranium and the transuranic elements in a substantially hexafluoride form (Figure 2).
Regarding claim 18, modified Amamoto teaches the method of claim 16, where Dugan teaches the moderator comprises helium, which is atomic number Z=2, thereby meeting the limitation of the instant claim.
Regarding claim 19, modified Amamoto teaches the method of claim 9, where Dugan teaches using the nanofuel in a nanofuel engine. Therefore, the nanofuel, ready for operation, must have been moved into a nanofuel engine.
Regarding claim 21, modified Amamoto teaches the method of claim 9, where Dugan teaches using the nanofuel in a nanofuel internal engine (p. 1, ¶ 1), which implies that the engine was configured to receive the nanofuel internally into said engine. Dugan further teaches the engine compressing the nanofuel internally and starting a fission energy production process using a neutron source (p. 1, ¶ 3 to p. 2, ¶ 2), wherein said energy production process provides a release of nuclear energy from a fission process (p. 2, ¶ 2).
Regarding claims 22, modified Amamoto teaches the method of claim 21 where Dugan teaches the nanofuel internal engine comprising at least one engine housing and at least one reflector (moderating reflector) (p. 20 and 22, Fig. 1 and 2).
Regarding claim 25, modified Amamoto teaches the method of claim 21 where Dugan teaches the nanofuel is received into an engine core of said nanofuel engine (primary working fluids is a mixture of uranium hexafluoride and helium…the primary working fluid …in the cylindrical core; p. 1) and said engine core is bounded by a first layer material (p. 22), as any contained core must be.
Regarding claim 29, modified Amamoto teaches the method of claim 21, where Dugan teaches the nanofuel is configured to include helium (p. 1, ¶ 1).
Regarding claim 31, modified Amamoto teaches the method of claim 21, where Amamoto and Dugan teach the nanofuel being produced from spent oxide fuel (column 1, lines 10-12), which one of ordinary skill in the art would recognize as being spent nuclear waste from a reactor, thereby meeting the limitations of claim 31.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Amamoto et al. (US 7,208,129 B2) in view of Dugan (“The Nuclear Piston Engine and Pulsed Gaseous Core Reactor Power Systems,” PhD Thesis, University of Florida, 1976), as applied to claim 1 above, and further in view of Kawamura et al. (US 2004/0170550 A1; hereinafter “Kawamura”).
Regarding claim 12, modified Amamoto teaches the method of claim 1, but does not specifically teach the mass fraction of plutonium in the transuranic elements product stream, and it is unclear how to count process steps in either the method of Amamoto or in the PUREX solvent extraction process.
However, like Amamoto, Kawamura also teaches a process of recovering uranium and plutonium from spent nuclear fuel via a fluorination step (abstract). Kawamura further teaches that it may be desirable to produce the plutonium at low purity in order to strengthen proliferation resistance ([0005]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to optimize the purity of the plutonium stream obtained in the method of modified Amamoto, including into the range of less than 99.8% purity. One of ordinary skill in the art would have been motivated to do so in order reduce proliferation concerns, as taught by Kawamura, while also achieving a stream of plutonium that would be useable in the method of Dugan, and which could therefore include substantial amounts of uranium.
Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over Amamoto et al. (US 7,208,129 B2) in view of Dugan (“The Nuclear Piston Engine and Pulsed Gaseous Core Reactor Power Systems,” PhD Thesis, University of Florida, 1976), as applied to claim 9 above, and further in view of Edlund et al. (U.S. Pat. No. 3,247,072 A; hereinafter “Edlund”).
Regarding claim 15, modified Amamoto teaches the method of claim 9, but does not teach the moderator comprising molecular hydrogen.
However, Edlund teaches the use of hydrogen-bearing vapor to moderate nuclear reactions (column 1, lines 13 and 14) with molecular hydrogen being one such vapor (column 3, line 46).
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to replace the helium moderator used by Dugan with the hydrogen vapor suggested by Edlund. It would have been obvious to do so because one would have been replacing one known neutron moderating gas with another with a reasonable expectation of success.
Claims 22-24 and 26-28 are rejected under 35 U.S.C. 103 as being unpatentable over Amamoto et al. (US 7,208,129 B2) in view of Dugan (“The Nuclear Piston Engine and Pulsed Gaseous Core Reactor Power Systems,” PhD Thesis, University of Florida, 1976), as applied to claims 21 and 25 above, and further in view of Moore (US Pat No. 3,549,490).
Regarding claims 22-24, modified Amamoto teaches the method of claim 21, where Dugan teaches the fundamentals of a nanofuel engine but is silent on many of the details of such an engine.
However, like Dugan, Moore teaches a nuclear driven internal engine (reciprocating type of motor directly driven by the power of a nuclear reactor, column 1, lines 14-15) that utilizes a piston and cylinder arrangement to convert the energy of the reactor to mechanical work (column 2, lines 40-43). The teachings of Moore on engine design are thus applicable reactors implementing the method of Dugan, such as the method of modified Amamoto.
Moore specifically teaches their engine comprising at least one engine housing (column 3, line 48) and at least one reflector (column 4, line 8), wherein said at least one housing comprises at least one channel (annular space 14; column 2, line 72 and Figure 1), wherein the channel comprises a coolant (cooling water; column 2, line 72-colum 3, line 1).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use a nanofuel engine in the method of modified Amamoto where the nanofuel engine comprises an engine housing comprising a channel, and where the channel comprises a coolant, as taught by Moore, thereby arriving at a method with the limitations of claims 22-24. One of ordinary skill in the art would have been motivated to do so because while Dugan is silent on many features required to implement their nanofuel engine, Moore provides such details for a similar piston based nuclear engine that houses a nuclear fuel.
Regarding claim 26, modified Amamoto teaches the method of claim 25, but neither Amamoto nor Dugan teach the engine core bounded by a first layer material and a second layer material to resist movement and create structure.
However, like Dugan, Moore teaches a nuclear driven internal engine (reciprocating type of motor directly driven by the power of a nuclear reactor, column 1, lines 14-15) that utilizes a piston and cylinder arrangement to convert the energy of the reactor to mechanical work (column 2, lines 40-43). The teachings of Moore on engine design are thus applicable reactors implementing the method of Dugan, such as the method of modified Amamoto.
Specifically, Moore teaches an nuclear reaction driven engine where the fuel is received into an engine core of the internal engine (nuclear fuel in the chamber 12’; column 4, lines 7-8), and said engine core (12’) is bounded by a first layer material (graphite and lead) and a second layer material (concrete) to resist movement and create structure (the reflector and shielding, column 4, lines 7-10; concrete will resist movement and create structure).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to in the method of modified Amamoto receive the nanofuel into an engine core where the engine core is bounded by a first layer material which has second layer material to resist movement and create structure, as taught by Moore. One of ordinary skill in the art would have been motivated to do so because while Dugan is silent on many features required to implement their nanofuel engine, Moore provides such details for a similar piston based nuclear engine that houses a nuclear fuel.
Regarding claim 27, modified Amamoto teaches the method of claim 26, where Dugan teaches a first layer material to contain the core being beryllium or beryllium oxide (p. 375-376) and Moore teaches the second layer material comprising concrete (column 4, lines 7-10), which includes cement. It is noted that while Moore utilizes graphite as a reflector, Dugan teaches that graphite is not ideal because it’s thermal absorption cross-section is too high for a practical piston engine configurations and beryllium and beryllium oxide would be better materials (p. 375-376).
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to use a material comprising beryllium in the first layer material surrounding the nuclear engine core, as taught by Dugan and cement in the second layer material, as taught by Moore. One of ordinary skill in the art would have been motivated to do so because Dugan teaches that beryllium makes an excellent and desirable reflector (p. 376, line 1) and because Moore teaches that concrete, which comprises cement, provides shielding so that there may be no emission of harmful radiation from the reactor (column 4, lines 7-10).
Regarding claim 28, modified Amamoto teaches the method of claim 21, where Dugan teaches the fundamentals of a nanofuel engine, including that fuel is mixed with helium, a neutron moderator, and the core is bound by a reflector (p. 376, ¶ 1). Dugan further teaches control of the temperature using a coolant to control the moderating reflector temperature (p. 386, ¶ 1). Dugan does not specifically teach the nanofuel internal engine being configured to receive coolant being in a channel, though this might be considered an obvious method of introducing a coolant to system that required it.
However, like Dugan, Moore teaches a nuclear driven internal engine (reciprocating type of motor directly driven by the power of a nuclear reactor; column 1, lines 14-15) that utilizes a piston and cylinder arrangement to convert the energy of the reactor to mechanical work (column 2, lines 40-43). The teachings of Moore on engine design are thus applicable reactors implementing the method of Dugan, such as the method of modified Amamoto.
In particular, Moore teaches the engine additionally comprising coolant in a channel (column 2, line 72-column 3, line 1), and therefore having a channel that is configured to receive coolant.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use a nanofuel engine in the method of modified Amamoto where the nanofuel engine is configured to receive coolant in a channel, as taught by Moore. One of ordinary skill in the art would have been motivated to do so because Dugan teaches that a coolant can be used to control temperature, and Moore further teaches that cooling by water in a channel is one specific method to distribute the cooling water in the engine.
Claim 30 is rejected under 35 U.S.C. 103 as being unpatentable over Amamoto et al. (US 7,208,129 B2) in view of Dugan (“The Nuclear Piston Engine and Pulsed Gaseous Core Reactor Power Systems,” PhD Thesis, University of Florida, 1976), as applied to claim 21 above, and further in view of the APHA report “Intrastate and Interstate Transportation of Spent Nuclear Fuel as a Public Health Risk” (hereinafter “APHA”, https://www.apha.org/policy-and-advocacy/public-health-policy-briefs/policy-database/2014/07/09/08/12/intrastate-and-interstate-transportation-of-spent-nuclear-fuel-is-a-public-health-risk, November 2010).
Regarding claim 30, modified Amamoto teaches the method of claim 21, but does not teach the geographic placement of said nanofuel engine. However, APHA teaches that it is appropriate to store spent nuclear fuel at a site where it is generated (page 7, “Principal Strategy 1”), as it would be after use in the nanofuel engine.
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to place said engine geographically adjacent to a spent fuel storage facility (claim 30).
One of ordinary skill in the art would have been motivated to do so in order to reduce the risks associated with the transportation of spent nuclear fuel (APHA, page 7, “Principal Strategy 1”).
Response to Arguments
Applicant’s arguments regarding the rejection of claims 6, 12, and 20 under 35 USC § 112, pages 19-21 of the reply filed 28 February 2026, have been fully considered, and are persuasive with respect to the prior rejections of claim 6 and 20, which are withdrawn.
However, claim 12 still lacks written description support in the as-filed disclosure. First, Applicant’s relies on Table IV, which “sets forth a table exemplary LWR SNF fractions”, but does not appear to represent any material that was obtained by the method of claim 1. Second, even if this were material that resulted from a method according to claim 1, a renormalized purity of 88.99% of a single sample does not provide sufficient support for the entire claimed purity range of less than 99.8%.
Additionally, Applicant’s reply does not address the concerns raised by the Examiner about the ambiguity of what constitutes a “step”, and so the rejection of claim 12 under 35 USC § 112(b) is maintained.
Applicant’s arguments regarding the rejection of claims 1-11, 13-14, 16-19, 21-22, 25, 29, and 31 under 35 USC § 103 have been fully considered, but they are not persuasive.
Specifically, Applicant argues on p. 25-26 that Dugan does not have a negative temperature coefficient of reactivity in the same way as required by the claims, and further asserts that Dugan “fails to recognize the claimed features.” However, the amended claims are understood as requiring a fissile fuel, a moderator, and a passive agent having a strong resonance neutron absorption cross section within a low epithermal range, which, when combined as taught Dugan, would inherently have the interactions recited in the claim.
Applicant’s arguments acknowledge that Dugan’s system would have the same interaction features as the instant invention,
“Even at 6.67 eV, the increased neutron population in the high-energy tail contributes more significantly to neutron loss than Doppler broadening of the cross-section itself.” (p. 28, ¶ 2)
and only assert that Dugan did not recognize them.
However, the fact that the inventor 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).
Applicant’s arguments that understanding the mechanism has design consequences, such as operating the nuclear piston engine at higher temperature, are also not persuasive because these design features do not appear in the rejected claims.
In response to applicant's argument that the examiner's conclusion of obviousness is based upon improper hindsight reasoning, 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). In this case, Amamoto’s method provides a way to process spent nuclear fuels, and Dugan’s nanofuel engine requires a source of fuel, that Amamoto’s method could provide. Their combination does not require any circuitous or reasoning using any knowledge gleaned from Applicant’s disclosure.
Applicant’s arguments with respect to claims 2-11, 13-14, 16-19, 21-22, 25, 29, and 31 raise no new issues, and are therefore also unpersuasive.
The prior rejections, as modified to suit the amended claims, are maintained.
Applicant’s arguments with respect to the rejection of claim 15 under 35 USC § 103, pages 32-33 of the reply, have been fully considered but are also unpersuasive.
Edlund need not teach all the features recited in the arguments in order to arrive at the instantly claimed invention. Edlund is used merely to teach that hydrogen can replace helium as a moderating material, which Applicant acknowledges is well-understood (last paragraph of p. 32). The remaining features would flow naturally from the substitution of hydrogen for helium in the nanofuel of Dugan.
Applicant’s recognition that the Bailey reference used in the rejection of claim 20 in the Office action mailed 9 December 2025 is the same Bailey reference used in the Office action and PTO-892 mailed on 23 April 2025 is appreciated.
Applicant’s arguments regarding the rejection of claim 20 under 35 USC § 103 have been fully considered and are persuasive in view of Applicant’s amendments to claim 20. Bailey does not teach or reasonable suggest incorporating the transuranic elements in the molecular mixture as a plasma form. The prior rejection of claim 20 is withdrawn.
However, amended claim 20 lacks written description support in the as-filed disclosure and so the claim is rejected under 35 USC § 112(a), as analyzed above.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Nicholas A Piro whose telephone number is (571)272-6344. The examiner can normally be reached Mon-Fri, 8:00 am-5:00 pm.
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/NICHOLAS A. PIRO/Assistant Examiner, Art Unit 1738
/PAUL A WARTALOWICZ/Primary Examiner, Art Unit 1735
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