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
1. Claims 7-11 are pending in this application and examined herein.
Response to Arguments
2. Applicant's arguments filed 08/21/25 have been fully considered but they are not persuasive.
3. Applicant argues that the “combination of Scott and Benson teach away from the claimed reactor.” A prior art reference that "teaches away" from the claimed invention is a significant factor to be considered in determining obviousness. However, "the nature of the teaching is highly relevant and must be weighed in substance. A known or obvious composition does not become patentable simply because it has been described as somewhat inferior to some other product for the same use." [In re Gurley, 27 F.3d 551, 553, 31 USPQ2d 1130, 1132 (Fed. Cir. 1994); MPEP 2145(X)(D)(1)]. Applicant’s arguments do not cite any portion of the applied references or any extrinsic evidence that the fuel salt of Scott’s reactor could not be replaced by a different fuel salt as taught by Benson. The examiner notes that Scott explicitly states that there are “many other options” for the “choice of molten salts.” And, Benson provides a list of molten salt material suitable for use in a nuclear reactor. Thus, the proposed modification of Scott is, in fact, motivated and suggested by the references themselves. Additionally, Applicant has not supplied an evidence to show that the proposed modification of Scott would render it unsatisfactory for its intended purpose [MPEP 2143.01(V)] or would change its principle of operation [MPEP 2143.01(VI)].
4. 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). The rejection sets forth the evidentiary basis for the conclusion of obviousness, and it is based on the applied references themselves combined with technical knowledge available to a skilled artisan.
5. In response to applicant's argument that the claimed invention has “particular advantages” not taught by the prior art, 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).
6. The rejections under 35 U.S.C. 103 are maintained.
Claim Rejections - 35 USC § 103
7. 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 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.
8. For applicant's benefit, the portions of the reference(s) relied upon in the below rejections have been cited to aid in the review of the rejections. While every attempt has been made to be thorough and consistent within the rejection, it is noted that prior art must be considered in its entirety, including disclosures that teach away from the claims. See MPEP 2141.02 VI.
9. 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.
10. Claims 7-11 are rejected under 35 U.S.C. 103 as being unpatentable over Scott, US 2016/0005497 in view of Benson et al., US 2019/0371482, in further view of Kruizenga et al., US 2020/0122109.
11. Regarding claim 7, Scott discloses a nuclear fission reactor (Fig. 1, [0001]) comprising: a reactor core, the reactor core comprising one or more containment units (102) containing fissile fuel ([0034]; a primary coolant system comprising a primary coolant, configured such that the primary coolant is in contact with the containment units and removes heat from the reactor core (see Fig. 1 and [0034-35]); the nuclear fission reactor comprises graphite arranged such that the graphite is in contact with the primary coolant during operation of the reactor ([0086], [0163]).
Scott further discloses that the primary coolant is a molten salt ([0035]+[0060]), providing a specific example of NaF/KF/ZrF4, while noting that there “are many other options” ([0060]). Benson teaches a molten salt nuclear reactor (Fig. 1, [0026]), and suggests that suitable molten salts include sodium fluoride and aluminum trifluoride1 ([0029]), listing many example salt eutectics ([0030-0046]), and suggesting that “many other eutectics may be possible” ([0029]). It is known that 54.5 NaF: 45.5AlF3 mixture forms a eutectic with a melting point of 700 °C,2 making it similar to several of the eutectic salts listed by Benson as suitable for use in molten salt reactors.
Accordingly, one of ordinary skill in the art at the time of invention/filing would have found it obvious to employ a molten salt comprising aluminum trifluoride and sodium trifluoride in the reactor of Scott, as suggested by Benson. Such a modification would provide the predictable result of increasing the useful operating temperature range due to the higher eutectic temperature of NaF-AlF3 as compared to the salt example of Scott. Moreover, both Scott and Benson establish that there are many possible options for molten salts suitable for use in molten salt nuclear reactors and [i]t 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. In re Leshin, 125 USPQ 416.
Scott does not disclose a system for providing contact between aluminium metal and the molten salt during operation of the reactor. Kruizenga teaches a system (Fig. 1 or Fig 2) for controlling impurities in a molten salt stream of a nuclear reactor ([0003]) that provides contact between a metallic form of an element of the coolant salt and the molten salt during operation of the reactor ([0005], [0030], [0034]).
One of ordinary skill in the art at the time of invention/filing would have found it obvious to combine the salt purification system of Kruizenga with the reactor of Scott for the predictable purpose of reducing impurities that may cause undesired behavior such as corrosion and change in salt stream properties ([0024]) in the coolant salt of Scott as modified by Benson.
In the exemplary systems of Kruizenga, the elemental metal beryllium is employed, which results in the addition of oxidized beryllium metal to the salt comprising BeF2 (see Figs. 1, 2 and [0030], [0034]). Accordingly, to employ the system of Kruizenga in the molten salt reactor of Scott as modified by the coolant salt suggested by Benson, one of ordinary skill in the art at the time of invention/filing would have found it obvious to use elemental aluminum in the purification system so that Al3+ ions are added to the coolant salt. Evidence for the obviousness of this modification is provided in Conocar et al., cited on the attached PTO-892.
12. Regarding claims 9 and 10, the reactor of Scott as modified by the coolant salt of Benson and the purification system of Kruizenga renders claim 7 obvious. As explained above, Scott and Benson both establish that molten salts in nuclear reactors should be at their eutectic point, which for NaF/AlF3 is 54.5 NaF: 45.5AlF3. One of ordinary skill in the art at the time of invention/filing would have found it obvious to modify the coolant salt of Scott as suggested by Benson for the reasons stated above.
13. Regarding claim 11, the reactor of Scott as modified by the coolant salt of Benson and the purification system of Kruizenga renders claim 7 obvious. Kruizenga further teaches a molten salt system wherein the system for providing contact between a metal and the molten salt comprises one or more of: a metal component in contact with the molten salt (Fig. 1, [0030]) ; a reducing agent supply unit configured to supply a reducing agent to the molten salt ([0031]); an electrolysis unit configured to electrolyse the molten salt (Fig. 2, [0034]). One of ordinary skill in the art at the time of invention/filing would have found it obvious to combine the salt purification system of Kruizenga with the reactor of Scott for the reasons stated above.
As explained above, in the exemplary systems of Kruizenga, the elemental metal beryllium is employed, which results in the addition of oxidized beryllium metal to the salt comprising BeF2 (see Figs. 1, 2 and [0030], [0034]). Accordingly, to employ the system of Kruizenga in the molten salt reactor of Scott as modified by the coolant salt suggested by Benson, one of ordinary skill in the art at the time of invention/filing would have found it obvious to use elemental aluminum in the purification system so that Al3+ ions are added to the coolant salt.
14. Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Benson et al., US 2019/0371482, in view of Kruizenga et al., US 2020/0122109.
15. Regarding claim 8, Benson discloses a nuclear fission reactor (Fig. 1, [0026]), the reactor comprising: a heat exchanger (135); a fuel salt system (102) comprising a reactor core (110) and a fuel salt ([0028), and configured such that the fuel salt flows between the reactor core and the heat exchanger (see Fig. 1) wherein: the fuel salt is a molten salt comprising aluminium trifluoride, sodium fluoride, and a chloride or fluoride of an element having a fissile isotope ([0028], [0047]); the nuclear fission reactor comprises graphite arranged such that the graphite (115) is in contact with fuel salt during operation of the reactor ([0048]).
Benson suggests that suitable molten salts include sodium fluoride and aluminum trifluoride3 ([0029]), listing many example salt eutectics ([0030-0046]), and suggesting that “many other eutectics may be possible” ([0029]). It is known that 54.5 NaF: 45.5AlF3 mixture forms a eutectic with a melting point of 700 °C,4 making it similar to several of the eutectic salts listed by Benson as suitable for use in molten salt reactors. Accordingly, one of ordinary skill in the art at the time of invention/filing would have found it obvious to employ NaF/AlF3 as a fuel salt based on the disclosure of Benson. 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. In re Leshin, 125 USPQ 416.
Benson does not disclose a system for providing contact between aluminium metal and the molten salt during operation of the reactor. Kruizenga teaches a system (Fig. 1 or Fig 2) for controlling impurities in a molten salt stream of a nuclear reactor ([0003]) that provides contact between a metallic form of an element of the coolant salt and the molten salt during operation of the reactor ([0005], [0030], [0034]).
One of ordinary skill in the art at the time of invention/filing would have found it obvious to combine the salt purification system of Kruizenga with the reactor of Benson for the predictable purpose of reducing impurities that may cause undesired behavior such as corrosion and change in salt stream properties ([0024]) in the in the fuel salt of Benson.
In the exemplary systems of Kruizenga, the elemental metal beryllium is employed, which results in the addition of oxidized beryllium metal to the salt comprising BeF2 (see Figs. 1, 2 and [0030], [0034]). Accordingly, to employ the system of Kruizenga in the molten salt reactor of Benson with the fuel salt comprising NaF/AlF3, one of ordinary skill in the art at the time of invention/filing would have found it obvious to use elemental aluminum in the purification system so that Al3+ ions are added to the coolant salt.
Conclusion
THIS ACTION IS MADE FINAL. 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 nonprovisional extension fee (37 CFR 1.17(a)) 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 mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SHARON M DAVIS whose telephone number is (571)272-6882. The examiner can normally be reached Monday - Thursday, 7:00 - 5:00 pm ET.
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/SHARON M DAVIS/Primary Examiner, Art Unit 3646
1 Aluminum’s most stable primary oxidation state is +3, making the “aluminum fluoride” of Benson equivalent to the “aluminum trifluoride” of the claim.
2 The eutectic point is an inherent physical property of a salt mixture. See, for example, Danielik cited on attached PTO-892.
3 Aluminum’s most stable primary oxidation state is +3, making the “aluminum fluoride” of Benson equivalent to the “aluminum trifluoride” of the claim.
4 The eutectic point is an inherent physical property of a salt mixture. See, for example, Danielik cited on attached PTO-892.