ML22024A042

Breakout Questions - Trp 141 - Identification of TLAAs

ML22024A042
Person / Time
Site:	Oconee
Issue date:	01/19/2022
From:	Angela Wu NRC/NRR/DNRL/NLRP
To:
Wu A, 301-415-2995
Shared Package
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References
Download: ML22024A042 (3)

Text

Oconee Nuclear Station (ONS) SLRA: Breakout Questions SLRA TLAA Section: Section 4.1, Identification of Time-Limited Aging Analyses TRP: 141 Question Number SLRA Section(s),

Table(s)

SLRA Page Background / Issue (As applicable/needed)

Discussion Question / Request A. Discussion Topics or Questions for SLRA TLAA Identification Methodology and Results -

Main Audit Portal Reference Document: ONS Calculation No. OSC-2077-03-SLR-0500, Revision 1 A.1 4.1.1, 4,1,2 Tables 4.1.4-1, 4.1.4-2, and 4.1.4-3 4

4-10 No questions at this time on those analyses identified as TLAAs in the SLRA versus those analyses that were identified either in the SLRA or the ONS calculation as not meeting one or more of the six criteria for TLAAs in 10 CFR 54.3(a).

For the SLRA, the staff confirmed the UFSAR bases for the HELB assessment do not involve time-dependent parameters defined by the current operating term (i.e., the ONS HELB basis in the CLB is different from that approved by the staff for many other NRC-licensed US PWRs)

No Questions at this time. Bases for all analyses evaluated in the ONS calculation as meeting or not meeting the definition of a TLAA in 10 CFR 54.3(a) are well explained, along with the criterion not met if the analysis is not a TLAA.

B. Discussion Topics or Questions for Regulatory Exemption Identification Methodology and Results -

Main Audit Portal Reference Document: ONS Calculation No. OSC-2077-03-SLR-0500, Revision 1 B.1 4.1.3 4-3 Topics and Regulatory Exemptions of Reference.

a) 10 CFR 50.60(b) Exemption Requested October 15, 1998 (ADAMS ML15112A279) and Approved on March 29, 1999 (ADAMS ML012050426) Under the Requirements of 10 CFR 50.12 - Exemption Request for use of ASME Code Cases N-514.

In SLRA Section 4.2.4 and in SLRA Tables 4.1.4-1 and 4.1.4-2, the applicant clearly identifies that the P-T limits calculated in accordance with the methods in 10 CFR Part 50, Appendix G are TLAAs for the ONS SLRA. In the staffs March 1999 safety evaluation approving the exemption, the staff granted the exemption in accordance with 10 CFR 50.12 and stated that the calculation of the LTOP system pressure lift setpoint is based on the specified P-T limit curve (it is in reference to the plant P-T limit cooldown curve) at

b) 10 CFR 50.60(b) Exemption Requested May 11, 1999 and Approved on July 29, 1999 (ADAMS ML012050097) Under the Requirements of 10 CFR 50.12 - Exemption Request for use of ASME Code Cases N-514, N-588, and Draft N-626 (currently N-640).

In the Table located on Page 11 of Appendix B of the referenced ONS calculations, the applicant evaluates whether the regulatory exemption of March 29, 1999 for using ASME Code Case N-514 (i.e., for LTOP system pressure lift and system arming temperature setpoints) is a 10 CFR 50.12-granted exemption that remains in effect and is based on a TLAA. The applicant clearly states in the table that the exemption allowing use of Code Case N-514 for calculation of the LTOP system setpoints is based on the results of the P-T limits that are established and calculated in accordance with the methodologies for P-T limit calculations in 10 CFR part 50, Appendix G. The applicant then states that the granted regulatory exemption for Code Case N-514 is not based on the results of a TLAA.

In the Table located on Page 12 of Appendix B of the referenced ONS calculations, the applicant evaluates whether the regulatory exemption of July 29, 1999 for using ASME Code Cases N-514 (a second request for using the code case), N-588, or Draft N-626 (now N-640) are based on TLAAs and remains in effect. On page 12 of the ONS calculation, the applicant quotes the following statement in the safety evaluation regarding a level less than or equal to 110 percent of the pressure limit set in the P-T curve (i.e., for the temperature associated with the arming temperature for the LTOP system in the P-T limit cooldown curve).

In regard to the Exemption of July 29, 1999 (for the request of May 11, 1999), which granted approval for the use of Code Cases N-588 and Draft N-626 (N-640), the staff agrees that the exemptions are not based on a TLAA. The staff also confirmed that, in the safety evaluation for the exemption request of May 11, 1999, the staff indicated that the exemption for use of Code Case N-514 was not necessary because the definition of the enable temperature as RTNDT = 90 ºF is found only in an NRC Branch Technical Position.

Thus, the staff has noted that two entirely different bases in regard to whether an exemption for use of Code Case N-514 exists in the CLBs for ONS Units 1, 2, and 3. The applicant should be prepared to discuss whether the Regulatory Exemption for use of ASME Code Case N-514 is still part of the CLB record (i.e., remains in effect), and if so, whether the exemption is based on a TLAA.

the need for an exemption of Code Case N514: Since the prior definition of the enable temperature as RTNDT = 90 ºF is found only in an NRC Branch Technical Position, an exemption is not required.