atw - International Journal for Nuclear Power | 2.2024
Internationale Entwicklungen und Trends
Internationale Entwicklungen und Trends
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Environment and Safety<br />
65<br />
ART Values <strong>for</strong> Westinghouse 3-loop RPV Nozzles<br />
Material<br />
IRT<br />
(°F)<br />
CF<br />
(°F)<br />
Fluence<br />
(1×10 19 n/cm²)<br />
FF<br />
Delta RT NDT<br />
(°F)<br />
Margin<br />
(°F)<br />
ART<br />
(°F)<br />
Inlet Nozzle -30 26.0 0.0116 0.12 3.1 3.1 -23.8<br />
Outlet Nozzle -70 65.6 0.0116 0.12 3.1 3.1 -54.2<br />
ART Values <strong>for</strong> OPR-1000 RPV Nozzles<br />
Material<br />
IRT<br />
(°F)<br />
CF<br />
(°F)<br />
Fluence<br />
(1×10 19 n/cm²)<br />
FF<br />
Delta RT NDT<br />
(°F)<br />
Margin<br />
(°F)<br />
ART<br />
(°F)<br />
Inlet Nozzle -60 20.0 0.00998 0.11 2.2 2.2 -55.6<br />
Outlet Nozzle -50 20.0 0.00998 0.11 2.2 2.2 -45.6<br />
Tab. 7.<br />
Calculation of ARTs Values <strong>for</strong> Westinghouse 3-loop and OPR-1000 Reactor Vessel Nozzle Materials at 48EFPY<br />
Based on the comparison of the nozzle P-T limit<br />
with beltline P-T limit curves from (Figs. 10~11),<br />
inlet and outlet nozzle P-T limit curves <strong>for</strong> cooldown<br />
and steady-state transient are all bounded<br />
by the beltline P-T limit curves.<br />
Fig. 10.<br />
Westinghouse 3-Loop RPV Nozzle and Beltline P-T Limit Curves<br />
5. Conclusion<br />
In this paper, the neutron fluence at reactor<br />
pressure vessel nozzle were evaluated using<br />
Ex-vessel neutron dosimetry (EVND) and surveillance<br />
capsule monitor close to reactor pressure<br />
vessel nozzle.<br />
To verify the evaluation results, best estimated<br />
result values from surveillance capsule and<br />
Ex-vessel neu tron dosimetry(EVND) were compared<br />
with transport calculated value and the<br />
comparison results meet the range of ±20% of the<br />
acceptance criteria applied when comparing the<br />
best estimated and calculated values specified in<br />
Regulatory Guide 1.190.<br />
Fig. 11.<br />
OPR-1000 RPV Nozzle and Beltline P-T Limit Curves<br />
Both Westinghouse 3-loop and OPR-1000 results meet<br />
the range of ±20% of the acceptance criteria applied<br />
when comparing the measured and calculated values<br />
specified in Regulatory Guide 1.190. Neutron fluence at<br />
Westinghouse 3-loop nozzle is 1.39×10 17 n/cm2 at<br />
48EFPY and Neutron fluence at OPR-1000 nozzle is<br />
1.20×10 17 n/cm2 at 48EFPY.<br />
Based on the neutron fluence at the reactor<br />
pressure vessel nozzle, P-T limit curves <strong>for</strong> the<br />
reactor pressure vessel nozzle region were<br />
evaluated and compared with the P-T limit curves<br />
<strong>for</strong> the reactor pressure vessel beltline region.<br />
The P-T limit curves <strong>for</strong> the reactor pressure<br />
vessel nozzle region were bounded by the P-T<br />
limit curves <strong>for</strong> reactor pressure vessel beltline<br />
region. In general, the neutron fluence at reactor<br />
pressure vessel nozzle is smaller than that of<br />
reactor beltline region. However due to the high<br />
stress in nozzle corner, the P-T limit curve <strong>for</strong> nozzle<br />
may become more limiting than that of beltline region.<br />
In conclusion, it is recommended that the reactor<br />
pressure vessel nozzle P-T limit curve evaluation<br />
should continuously be per<strong>for</strong>med in order to confirm<br />
if nozzle P-T limit curves are bounded by beltline<br />
curves during the plant life.<br />
Vol. 69 (2024)
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