ML22024A056

Breakout Questions - Trps 142.1 and 149.13 - Fluence

ML22024A056
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Site:	Oconee
Issue date:	01/19/2022
From:	Angela Wu NRC/NRR/DNRL/NLRP
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Wu A, 301-415-2995
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Oconee (Units 1, 2, and 3) SLRA: Breakout Questions SLRA Section 4.2.1: Neutron Fluence Projections TRP 142.1: Neutron Fluence

Question SLRA SLRA Background / Issue Discussion Question / Request Number Section Page (As applicable/needed) 1 4.2.1 4-22

• Bk : S of ANP -389 Please, explain why there is scs the dpa adjtment mdology confidence in the dpa at the for the e*tended beline soned location of interest in the in the SA. extended beltline and not in the fluence. In other words,

Purpose:

To better understand the dpa why is a multiplier needed for adjustment methodology employed for the dpa and not fluence, if dpa is extended beltline. typically calculated with fluence as an input. That is to say that elementary displacement theory states that the dpa is typically a product of the fluence, the scattering cross section, and the number of displacements produced per primary knock-on atom (PKA).

2 4.2.1 4-22

• Bk The dpa aent m Please explain the basis of described inon 2.3 NP -389s this relationship and whether sng that tling rationsis differences in the neutron icabl spectrum from the beltline to

(. )= ( ) the extended beltline would

(. )( )affect the validity.

Purpose:

To better understand the dpa adjustment methodology employed for the extended beltline.

3 4.2.1 4-23

• Bk O -23 of the SAt is Pleasn how the sn the vent m e of 1.m2 w

analysis of the Linde 80 reactor pressure calculated for the RPV vessel nozzle welds reported in BAW-2192, nozzles welds in BAW-2192, Revision 0, Supplement 1P-A, R evision 0 Revision 0 Supplement 1P-A,

[Reference 4.2-13] and BAW-2178, Revision 0 and BAW-2178, Revision 0, Supplement 1P-A, Revision 0 Revision 0, Supplement 1P-A,

[Reference 4.2-14]) utilized an inside wetted Revision 0 and why that surface fluence of 1.5E+18 n/cm2. This is method was not employed for significantly higher than the 72 EFPY inside the SLRA.

wetted surface fluence values for the reactor pressure vessel nozzle welds reported in Table 4.2.1-1, Table 4.2.1-2, and Table 4.2.1-3 (highest at 3.50E+17 n/cm2).

Purpose:

To understand why there are differences in fluence calculations and methodologies used in the SLRA and BAW -

2192, Revision 0 Supplement 1P-A, Revision 0 and BAW-2178, Revision 0, Supplement 1P-A, Revision 0.

SLRA Section 4.7.1.3: Reactor Vessel Internals Irradiation Embrittlement TRP 149.13 : Reactor Vessel Internals Irradiation Embrittlement

Question SLRA SLRA Background / Issue Discussion Question / Request Number Section Page (As applicable/needed) 1 4.7.1.3 B-64

• Bk SA Please clify and e*ai and states that As discsed in MRP-9, w the fle valu B2.1.7 RisiSons RP -1. 3 that ar

, neutron e*pos are best-R eactor Vs mate vuesn units of disacem Inals TLAA are best-per atom0 cendarears monsvativ of operation,ce prted from isng 60- yearon. In m iessents atomues

reported in MRP-189, Revision 3, are obtained from a conservative extrapolation of discrete ordinate transport 60-year best estimate analyses to 80-years to bound the B&W fleet. The 60-year discrete ordinate transport displacements per atom values were obtained using methods that comply with Regulatory Guide 1.190 for the reactor vessel as reported in BAW-2241NP -A, Revision 2.

Purpose:

To better understand the fluence values used for the reactor vessel internals TLAA.

2 4.7.1.3 4-119

• Bk S.1.3 of the SA Pleasn w there is states that Y sh a l dienc e valuoped for the update e values of -ision 1 ed to sporthe Reactor (S - are TLAA and arVsnals TLAA and the obtaiomence 4.7-S -specificCNP/ -

e inpue deved o cc fle vs ation of 60-yeareactors TLAA alsAW-inals traport cculationsw P-A meogy.

devsiGi methodologyimisc discr nates traport 3-Dynthesis m)eactor vss described i n BAW - 2241PA Risie csisihe timted in MRP -189, RisiRence 4.7-i BAW -2241PA, Rision 2 methodologys myoncned wieactors ome specic ming

enhancements were required in order to accurately represent the reactor vessel internals components.

Additionally, Section 5.6 of ANP-3899NP states that The fluence/dpa used for the Oconee gap analysis (GALL SLR XI.M16A), which is based on MRP-189 Revision 3 and was developed to bound the B&W fleet of reactors, is reported in Table 5-2.

Furthermore, Table 5-3 of ANP -3899P compares the fluence values used to support TLAA and the ONS-specific MCNP and DORT-calculated fluence values.

Purpose:

To better understand the fluence values used as input to the TLAA and the ONS-specific MCNP/DORT-calculated fluence values.