ML20112F508

2020-04-15 Summary Table of Proposed Safety Evaluation Changes 4015

ML20112F508
Person / Time
Site:	Electric Power Research Institute
Issue date:	04/16/2020
From:	Jordan Hoellman NRC/NRR/DANU/UARP
To:
Jordan Hoellman, NRR/DANU/UARP, 415-5481
Shared Package
ML20112F498	List: ML20112F506 ML20112F508
References
EPRI-AR-1
Download: ML20112F508 (3)

Text

Summary Table of Proposed Safety Evaluation Changes with Rationale No. Location Proposed Change Rationale / Comments

1. p. 2, Section 3.1, last Concerning reliance on historical data, use the EPRI believes the revised statement is a more precise statement paragraph actual quote from Topical Report (TR) p. 1-4 of what does not rely on historical data.

rather than paraphrasing the report.

2. p. 3, Section 3.2, last Delete the last two sentences of the paragraph. EPRI is concerned that the words limited scope could convey paragraph the incorrect impression that the topical report is somehow incomplete and needs to be supplemented. (Note: The words limited scope on Topical Report p. 2-4 were intended to apply to the data from AGR-1 and AGR-2, not to the report.) EPRI recognizes the Figure 2-1 alludes to the possibility of one or more future topical reports, but that possibility does not pertain to the regulatory bases of this TR. Accordingly, the last two sentences seem unnecessary and potentially misleading.

3. p. 4, Section 3.4 Modify the characterization of the IPyC and The current wording seems to convey that the PyC layers handle OPyC layers. all of the load (pressure) while the SiC layer handles fission product retention. The actual functions of the layers are more complex and interwoven. For example, SiC is the primary pressure boundary layer, but the PyC layers impact its stress state by putting it in compression during irradiation; also, the PyC layers function to contain gaseous fission products.

4. p. 4, Section 3.5, NRC Modify the characterization of Figure 5-2. The current wording could be taken to imply that Figure 5-2 is an Staff Evaluation expected grain size, while the TR states that the figure shows a limiting large grain size and the actual grain size should be smaller. The suggested changes are consistent with the new TR Section 5.3.2.4.

5. p. 7, Section 3.5, NRC Delete instead of a much smaller number of EPRI is uncomfortable with the comparison of light water reactor Staff Evaluation, 2nd full fuel elements with tighter tolerances. fuel to TRISO fuel, and in particular, comparing the tolerances of paragraph on page each. It does not seem appropriate to characterize tolerances on different parameters for different products as tighter or looser. It seems very much like comparing apples and oranges.

6. p. 7, Section 3.5, NRC Delete large where it is modifying functional The meaning of large in this context is unclear, and it does not Staff Evaluation, 2nd containment approach. appear to be necessary.

full paragraph on page 1

No. Location Proposed Change Rationale / Comments

7. p. 8, Section 3.5, NRC Change substantially to mostly. There is potential ambiguity with the current wording.

Staff Evaluation, last Substantially within the boundaries could be interpreted to paragraph, 2nd to last mean not only within the boundaries but well within the sentence boundaries. It is EPRIs understanding that the NRC intent is consistent with mostly (or generally or largely) within the boundaries.

8. p. 8, Section 3.6, first Modify the discussion of the cause of the The topical report discussed two different causes for power paragraph increases in power seen during the experiment. increases - a general trend due to depletion of boron during the first several cycles (p. 6-7) and an end of cycle increase in some cycles due to rotation of control drums (p. 6-10). The NRC wording increase in power during the experiment seems to refer to the general trend. The suggested revisions to the wording focus on that burnable absorber depletion effect.

9. p. 9, Section 3.6, NRC Change vendor to future license applicant. Clarifies the ultimate responsibility.

Staff Evaluation, first full paragraph on page

10. p. 9, Section 3.6, NRC Change manufacturing specifications in Section With the revisions to the TR, there are no manufacturing Staff Evaluation, 5 to parameter envelope in Table 5-5. specifications in Section 5.

second full paragraph on page, last sentence

11. p. 9, Section 3.6, NRC Modify wording of paragraph. The different types of fission products and associated Staff Evaluation, last measurements in AGR-1 and -2 can be difficult to follow. The paragraph proposed changes are intended to clarify the discussion.

The modified wording also corrects a typo (Condition 2 should be Condition 3).

12. p. 10, Section 3.7, third Modify discussion of silver depletion. The changes clarify that the initial release (and depletion) of paragraph on page silver was not all of the silver in the compact but the silver outside the TRISO particles.

Also, isotope is changed to element because the more general term is appropriate for europium and strontium.

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No. Location Proposed Change Rationale / Comments

13. p. 11, Section 3.7, NRC Modify wording of paragraph. EPRI agrees with the NRC that the data can be used to empirically Staff Evaluation, 2nd to evaluate failure probabilities of populations of TRISO particles last paragraph with characteristics consistent with the AGR fuel and subjected to similar irradiation conditions. However, EPRI is concerned the current wording of the paragraph could lead to some overly pessimistic impressions of the state of knowledge concerning TRISO fuel behavior and the utility of the AGR data. In particular, the current text could be taken as implying (i) the results presented did not provide any data on particle failure mechanisms and (ii) the empirical data cannot be used in fuel performance model validation activities. Notwithstanding the challenges inherent in modeling some of the key phenomena, the AGR-1 and -2 tests provided important insights into the causes of the few particle failures that were experienced, as described in Section 7.4 of the TR.

14. p. 12, Section 3.8, NRC Add krypton to the parenthetical list of elements Kr-85 is an important isotope and it is discussed in Sections 7.3.5 Staff Evaluation, with isotopes discussed in Sections 6.7, 6.8, 7.1, and 7.3.6.

paragraph 3 and 7.3.

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