ML18338A517
| ML18338A517 | |
| Person / Time | |
|---|---|
| Issue date: | 03/13/2019 |
| From: | Jordan Hoellman NRC/NRO/DLSE/LB4 |
| To: | |
| Hoellman J/415-5481 | |
| Shared Package | |
| ML18338A515 | List: |
| References | |
| NUREG-0800 | |
| Download: ML18338A517 (4) | |
Text
RESPONSE TO PUBLIC COMMENTS ON DRAFT STANDARD REVIEW PLAN BRANCH TECHNICAL POSITION (BTP) 5
-3, FRACTURE TOUGHNESS REQUIRMENTS On September 20, 2018, a Notice of Reopening of for Public Comment was published in the Federal Register (8 3 FR 47647) on the proposed revision to NUREG
-0800, Standard Review Plan (SRP), BTP 5-3, Fracture Toughness Requirements. Comments were received from one (1) organization.
Electric Power Research Institute 3420 Hillview Avenue Palo Alto, CA 94304
-1338 The comments can be found in ML18260A080
. The NRC's staff review and disposition of the comments are provided in the following table.
No. Reference Comment Submission NRC Resolution 1 1. Section A, Background, final paragraph, last sentence: "Based on the change
-in-risk analyses documented in the memorandum, the NRC determined that the methodologies in B1.1 and B1.2 can be used in pressure
-temperature limits and PTS evaluations for up to 72 effective full power years of operation."
- a. Comment: EPRI recommends that the sentence be revised as follows: "Based on the change
-in-risk analyses documented in the memorandum, the NRC determined that the methodologies in B1.1 and B1.2 can be used in pressure
-temperature limits and PTS evaluations for up to 80 years of operation."
- b. Justification: The justification for this recommended change is based on the information presented in the NRC Closure Memorandum [
3], Enclosure 5, "Technical Assessment by Division of Engineering and Division of Risk Assessment on Risk Assessment of Pressurized Thermal Shock The NRC staff concurs that modifying the text from 72EFPY to 80EFPY is justified by the analyses conducted by the staff under the conditions noted by the commenter.
The NRC staff will modify the draft text as proposed in this comment.
Event for 72 EFPYs Considering Non
-conservatism in BTP 5
-3." The data in Table 1 in Section 3.1.3 documents the NRC staff's change in through
-wall cracking frequency (TWCF) values for the four limiting BTP plants at 72 EFPYs. Section 3.2.2.2.4 states, The results of the NRC staff's change
-in-risk analyses were summarized in Table 1 in Section 3.1.3 where the bounding increases in risk were reported as 2.14E
-8/year, 2.31E
-9/year, 7.70E
- 11, and 7.81E
-11/year for IP
-2, Palisades, WB
-1, and NA-1, respectively, considering the extremely conservative case that the adjustment for the BTP 5
-3 non-conservatism is 200 % of the required (i.e., increased by 37 °F) for plates and non- Rotterdam forgings and 150 % of the required (i.e., increased by 136 °F) for Rotterdam forgings. These change
-in-risk increases are well below the guideline for a plant-specific backfit as described in NUREG/BR-0058 and discussed in Section 3.2.2.2.1 of this document.
First, it is noted that the two plants cited above which have the highest increases have announced plans to shut down within the next four years, before 60 years of plant operation are reached. Second, referring to Table 1 in Section 3.1.3, it is noted that the remaining two limiting plants have substantially lower through
- wall cracking frequency (TWCF) and change in TWCF values (e.g., one or two orders of magnitude lower) than the two plants shutting down.
Incorporating the change recommended above to extend the allowable use of BTP 5
-3 from 72 EFPY to 80 years of operation would result in a small increase in adjusted reference temperature of the beltline ring forgings (about a 4°F increase according to the shift prediction equations of 10CFR50.61a, at a conservative assumption of 80 EFPY). Such an increase would have negligible impact on the conclusions of the technical assessment documented in [3].
Therefore, it is reasonable to remove the unnecessary limitation of "72 EFPY" and permit plants to use BTP 5
-3 through a full 80 year license period which may exceed 72 EFPY by a small amount. 2. Section B, paragraph 1.2, "Estimation of Charpy V
-Notch Upper Shelf Energies," third sentence: "Beltline materials are defined to be those materials directly surrounding the effective height of the active core and adjacent materials estimated to receive a neutron fluence of 1 x 10 17 n/cm 2 (E > 1.0 MeV) or higher." a. Comment: Industry recommends that the NRC revise the beginning of this sentence to read, "Consistent with RIS 2014-011, beltline materials are considered to be those materials-"
- b. Justification
- The reactor vessel beltline is officially defined in 10 CFR 50, Appendix G, Section II, Definition F
[4]. NRC RIS 2014
-011 [5] provides the current NRC staff interpretation of the definition given in Appendix G; thus, the recommended phraseology is more accurate. The NRC staff concur s with the commenter that RIS 2014-011 provides an interpretation of the definition given in 10 CFR 50, Appendix G. RIS 2014-011 is a restatement of the regulatory requirements as they exist during the drafting of this revision to BTP 5
-3 and was written to clarify the Appendix G definition
. The NRC staff also agree s that reference to RIS 2014-011 is beneficial to the revision and propose to add the reference to RIS 2014
-011 to the sentence as recommended by the commenter
- Consistent with Regulatory Issue Summary 2014
-011, "Information on Licensing Applications for Fracture Toughness Requirements for Ferritic Reactor Coolant Pressure Boundary Components," beltline materials are considered to be those materials directly surrounding the effective height of the active core and adjacent materials estimated to receive a neutron fluence of 1 x 10 17 n/cm 2 (E > 1.0 MeV) or higher.
This definition is derived from the definition of beltline in 10 CFR 50.61 and considers the neutron fluence zone of interest as defined in 10 CFR Part 50, Appendix H(III)(a).
RIS 2014-011 will also be added to the reference section: U.S. Nuclear Regulatory Commission, Regulatory Issue Summary 2014
-11, "Information on Licensing Applications for Fracture Toughness Requirements for Ferritic Reactor Coolant Pressure Boundary Components."