Prosecution Insights
Last updated: April 19, 2026
Application No. 18/299,588

USE OF BURNABLE ABSORBERS IN GRAPHITE MATRIX OF TRISO-FUELED COMPACTS IN NUCLEAR CORES

Non-Final OA §102§103§112
Filed
Apr 12, 2023
Examiner
WASIL, DANIEL D
Art Unit
3646
Tech Center
3600 — Transportation & Electronic Commerce
Assignee
Westinghouse Electric Company LLC
OA Round
1 (Non-Final)
80%
Grant Probability
Favorable
1-2
OA Rounds
3y 1m
To Grant
99%
With Interview

Examiner Intelligence

Grants 80% — above average
80%
Career Allow Rate
524 granted / 656 resolved
+27.9% vs TC avg
Strong +25% interview lift
Without
With
+25.1%
Interview Lift
resolved cases with interview
Typical timeline
3y 1m
Avg Prosecution
36 currently pending
Career history
692
Total Applications
across all art units

Statute-Specific Performance

§101
4.7%
-35.3% vs TC avg
§103
34.6%
-5.4% vs TC avg
§102
19.7%
-20.3% vs TC avg
§112
38.0%
-2.0% vs TC avg
Black line = Tech Center average estimate • Based on career data from 656 resolved cases

Office Action

§102 §103 §112
DETAILED ACTION Elections Claims 1-20 are pending. Applicant’s election of Invention I and species B/c/vi/x without traverse in the Reply filed 15 December 2025 is acknowledged. The elected Invention/species encompasses claims 1-14. Claims 15-20 are withdrawn from further consideration as being drawn to nonelected Invention(s). The restriction requirement is deemed proper and is therefore made FINAL. Claim Rejections - 35 USC § 112 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 1-14 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which an inventor regards as the invention. Claim 1 The claim requires distinct elements comprising: some fissile fuel particles; a graphite matrix surrounding said some particles; and a neutron absorber. How the elements are linked (related) to each other is unknown and unclear. For example, the claim does not require that any of the elements contact any of the other elements. That is, the claim allows for the elements to be separated (distant) from each other. Thus, how the structural cooperative relationships (if any) of the distant elements result in a “composite fueled compact” is unknown and unclear. It is unclear whether the fissile fuel particles and the neutron absorber are both dispersedly embedded in the graphite matrix, where the neutron absorber is located outside of the fissile fuel particles. Claims 8-9 The phrase “neutron absorber is comprised of” is unclear. For example, it is unclear whether the “comprised of” in the phrase means “consists of”, or “comprises”, or something else. Claims 10-11 The neutron absorber concentration is unclear. The phrase “or less” allows for zero. This conflicts with claim 1 which requires a neutron absorber. Claims 10-12 The phrase “"based on the weight of the matrix" is unclear, For example, it is unclear whether the weight refers to: the graphite matrix alone; a combination of the graphite matrix and (with) the fissile fuel; or something else. Review The claims do not allow the public to be sufficiently informed of what would constitute infringement. Any claim not specifically addressed is rejected based upon its dependency. Claim Rejections - 35 USC § 102 The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless –- (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claims 1-3, 6, and 8-9, as best understood, are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Evans (“Burnable Absorbers in Nuclear Reactors – A Review”, May 2022). Evans (cited via IDS) teaches a composite fueled compact comprising fissile fuel particles, a graphite matrix, and a neutron absorber. The fuel comprises TRISO fuel (or QUADRISO fuel). The neutron absorber can comprise boron carbide and/or a gadolinium oxide (e.g., page 42, at line 8). Particularly note Evans at page 44 and lines 4-8, which state: “QUADRISO fuel has been proposed, which adds an additional BA layer to the standard TRISO fuel design. Alternatively, it may be more straightforward to include a dispersion of burnable absorbers into the carbon matrix compact or the fuel kernel without the need to alter the TRISO layers.” Claims 1-6, 8-9, and 14, as best understood, are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Washington ("Selection and evaluation of potential burnable absorbers incorporated into modified TRISO particles", August 2014). Washington (cited via IDS) teaches a composite fueled compact comprising fissile fuel particles, a graphite matrix, and a neutron absorber. The fuel comprises TRISO fuel (or QUADRISO fuel). The neutron absorber can comprise boron carbide and/or a gadolinium oxide. Particularly note page 378, sec. 1, lines 1-4; page 380, sec. 2; page 380, sec. 4.1; Table 2; and Figure 2. The composite fueled compact has a cylindrical geometry (e.g., (p. 378, sec. 2.1, par. 3, lines. 6-10). 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. Claims 4-5, 7, and 10-14, as best understood, are rejected under 35 U.S.C. 103 as being unpatentable over Evans as applied to claims 1, 6, and 8 above, and further in view of Washington. Claims 4-5 Washington shows that it is well known in the art to use fissile fuel having an initial enrichment level greater than 10% (e.g., page 380, sec. 4.1). One of ordinary skill in the art would realize that nuclear fuel can be implemented with various enrichments, necessarily amounting to certain design characteristics obviously more favorable to use of a certain enrichments in light of the specific nuclear reactor design. Thus, it would have been obvious to one of ordinary skill in the art to have modified Evans to have implemented the fuel with an initial enrichment greater than 10%, as suggested by Washington, to meet a particular reactor design. The result of the modification would have been predictable to the skilled artisan. Claim 7 It would have been obvious to one of ordinary skill in the art to have to have uniformly distributed the neutron absorber in Evans in order to have a known even effect throughout the matrix, especially in the absence of any reason for the contrary. The result of the modification would have been predictable to the skilled artisan. Claims 10-12 It would have been obvious to one of ordinary skill in the art to have modified Evans (if necessary) to have optimized the concentration of neutron absorbers in the graphite matrix in a case-by-case basis, depending on the geometry and the materials of the reactor core (i.e., particular reactor design), so as to achieve the desired result regarding reactivity, flux flattening, reactor lifetime, fuel burnup, etc. Additionally, the skilled artisan would optimize said concentration depending on the specific neutron absorber used. Thus, the choice of a preset neutron absorber concentration, to meet a particular reactor design, would have been obvious to one of ordinary skill in the art. The result of the modification would have been predictable to the skilled artisan. Claim 13 It is well known in the art to surround an element with a layer that comprises a portion of the neutron absorber. For example, Evans discloses having a neutron absorber both dispersed in fuel and surrounding the fuel (e.g., Fig. 4 far right). Thus, it would have been obvious to one of ordinary skill in the art to have to have surrounded Evans’ graphite matrix in with a layer that comprises a portion of the neutron absorber to better control absorbing as needed in a particular reactor design. The result of the modification would have been predictable to the skilled artisan. Claim 14 Washington shows that it is well known in the art to have a composite fueled compact with a cylindrical geometry (e.g., (p. 378, sec. 2.1, par. 3, lines. 6-10). Thus, it would have been obvious to one of ordinary skill in the art to have modified Evans to have implemented a cylindrical geometry, as suggested by Washington, to meet a particular reactor design. The result of the modification would have been predictable to the skilled artisan. Objection to the Drawings The drawings are objected to as failing to comply with 37 CFR 1.84(p)(5) because they do not include the reference numeral “38” mentioned in the description. The drawings are further objected to under 37 CFR 1.83(a). The drawings must show every feature specified in the claims or the feature(s) must be canceled from the claim(s). No new matter should be entered. These recited features are not shown: a layer surrounding the graphite matrix (claim 13). where the layer comprises a portion of the neutron absorber (claim 13). Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance. Objection to the Abstract The Abstract is objected to because it refers to a non-elected invention. The Abstract is also objected to for the reasons set forth above in the 35 U.S.C. 112(b) rejection of claim 1. An Abstract should include that which is new in the art to which the recited invention pertains. Correction is required. See MPEP § 608.01(b). Objection to the Title The Title is objected to because it refers to non-claimed subject matter. The following Title is suggested: “Composite Fueled Compact Comprising Burnable Absorbers Distributed Throughout A Graphite Matrix Which Contains TRISO Fuel Particles”. The Applied References For Applicant’s benefit, portions of the applied reference(s) have been cited (as examples) to aid in the review of the rejection(s). While every attempt has been made to be thorough and consistent within the rejection, it is noted that the prior art must be considered in its entirety by Applicant, including any disclosures that may teach away from the claims. See MPEP 2141.02 (VI). Application Status Information Applicants seeking status information regarding an application should check Patent Center on the Office website at www.uspto.gov/PatentCenter. Alternatively, the requester may contact the Application Assistance Unit (AAU). See MPEP § 1730, subsection VI.C. See MPEP § 102 for additional information on status information. For a USPTO Customer Service Representative call 800-786-9199 or 571-272-1000. 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 Daniel Wasil can be reached at (571) 272-4654, on Monday-Thursday from 10:00-4:00 EST. Supervisor Jack Keith (SPE) can be reached at (571) 272-6878. /DANIEL WASIL/ Examiner, Art Unit 3646 Reg. No. 45,303 /JACK W KEITH/Supervisory Patent Examiner, Art Unit 3646
Read full office action

Prosecution Timeline

Apr 12, 2023
Application Filed
Feb 19, 2026
Non-Final Rejection — §102, §103, §112 (current)

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Prosecution Projections

1-2
Expected OA Rounds
80%
Grant Probability
99%
With Interview (+25.1%)
3y 1m
Median Time to Grant
Low
PTA Risk
Based on 656 resolved cases by this examiner. Grant probability derived from career allow rate.

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