View all text of Subjgrp 108 [§ 50.50 - § 50.69]
§ 50.61 - Fracture toughness requirements for protection against pressurized thermal shock events.
(a) Definitions. For the purposes of this section:
(1) ASME Code means the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section III, Division I, “Rules for the Construction of Nuclear Power Plant Components,” edition and addenda and any limitations and modifications thereof as specified in § 50.55a.
(2) Pressurized Thermal Shock Event means an event or transient in pressurized water reactors (PWRs) causing severe overcooling (thermal shock) concurrent with or followed by significant pressure in the reactor vessel.
(3) Reactor Vessel Beltline means the region of the reactor vessel (shell material including welds, heat affected zones and plates or forgings) that directly surrounds the effective height of the active core and adjacent regions of the reactor vessel that are predicted to experience sufficient neutron radiation damage to be considered in the selection of the most limiting material with regard to radiation damage.
(4) RT
(5) RT
(6) EOL Fluence means the best-estimate neutron fluence projected for a specific vessel beltline material at the clad-base-metal interface on the inside surface of the vessel at the location where the material receives the highest fluence on the expiration date of the operating license.
(7) RT
(8) PTS Screening Criterion means the value of RT
(b) Requirements. (1) For each pressurized water nuclear power reactor for which an operating license has been issued under this part or a combined license issued under Part 52 of this chapter, other than a nuclear power reactor facility for which the certification required under § 50.82(a)(1) has been submitted, the licensee shall have projected values of RT
2 Changes to RT
(2) The pressurized thermal shock (PTS) screening criterion is 270 °F for plates, forgings, and axial weld materials, and 300 °F for circumferential weld materials. For the purpose of comparison with this criterion, the value of RT
(3) For each pressurized water nuclear power reactor for which the value of RT
(4) For each pressurized water nuclear power reactor for which the analysis required by paragraph (b)(3) of this section indicates that no reasonably practicable flux reduction program will prevent RT
(5) After consideration of the licensee's analyses, including effects of proposed corrective actions, if any, submitted in accordance with paragraphs (b)(3) and (b)(4) of this section, the Director, Office of Nuclear Reactor Regulation, may, on a case-by-case basis, approve operation of the facility with RT
(6) If the Director, Office of Nuclear Reactor Regulation, concludes, pursuant to paragraph (b)(5) of this section, that operation of the facility with RT
(7) If the limiting RT
(c) Calculation of RT
(1) Equation 1 must be used to calculate values of RT
(i) If a measured value of RT
3 The class of material for estimating RT
(ii) For generic values of weld metal, the following generic mean values must be used unless justification for different values is provided: 0 °F for welds made with Linde 80 flux, and −56 °F for welds made with Linde 0091, 1092 and 124 and ARCOS B-5 weld fluxes.
(iii) M means the margin to be added to account for uncertainties in the values of RT
(A) In Equation 2, σ
(B) In Equation 2, σ
(iv) ΔRT
(A) CF (°F) is the chemistry factor, which is a function of copper and nickel content. CF is given in table 1 for welds and in table 2 for base metal (plates and forgings). Linear interpolation is permitted. In tables 1 and 2, “Wt − % copper” and “Wt − % nickel” are the best-estimate values for the material, which will normally be the mean of the measured values for a plate or forging. For a weld, the best estimate values will normally be the mean of the measured values for a weld deposit made using the same weld wire heat number as the critical vessel weld. If these values are not available, the upper limiting values given in the material specifications to which the vessel material was fabricated may be used. If not available, conservative estimates (mean plus one standard deviation) based on generic data
4
4 Data from reactor vessels fabricated to the same material specification in the same shop as the vessel in question and in the same time period is an example of “generic data.”
(B) f is the best estimate neutron fluence, in units of 10
19 n/cm
2 (E greater than 1 MeV), at the clad-base-metal interface on the inside surface of the vessel at the location where the material in question receives the highest fluence for the period of service in question. As specified in this paragraph, the EOL fluence for the vessel beltline material is used in calculating KRT
(v) Equation 4 must be used for determining RT
(2) To verify that RT
5 Surveillance program results means any data that demonstrates the embrittlement trends for the limiting beltline material, including but not limited to data from test reactors or from surveillance programs at other plants with or without surveillance program integrated per 10 CFR part 50, appendix H.
(i) Results from the plant-specific surveillance program must be integrated into the RT
(A) The materials in the surveillance capsules must be those which are the controlling materials with regard to radiation embrittlement.
(B) Scatter in the plots of Charpy energy versus temperature for the irradiated and unirradiated conditions must be small enough to permit the determination of the 30-foot-pound temperature unambiguously.
(C) Where there are two or more sets of surveillance data from one reactor, the scatter of ΔRT
(D) The irradiation temperature of the Charpy specimens in the capsule must equal the vessel wall temperature at the cladding/base metal interface within ±25 °F.
(E) The surveillance data for the correlation monitor material in the capsule, if present, must fall within the scatter band of the data base for the material.
(ii)(A) Surveillance data deemed credible according to the criteria of paragraph (c)(2)(i) of this section must be used to determine a material-specific value of CF for use in Equation 3. A material-specific value of CF is determined from Equation 5.
(B) In Equation 5, “n” is the number of surveillance data points, “A
(iii) For cases in which the results from a credible plant-specific surveillance program are used, the value of σ
(iv) The use of results from the plant-specific surveillance program may result in an RT
(3) Any information that is believed to improve the accuracy of the RT
Table 1—Chemistry Factor for Weld Metals, °F
Copper, wt-% | Nickel, wt-% | 0 | 0.20 | 0.40 | 0.60 | 0.80 | 1.00 | 1.20 | 0 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 0.01 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 0.02 | 21 | 26 | 27 | 27 | 27 | 27 | 27 | 0.03 | 22 | 35 | 41 | 41 | 41 | 41 | 41 | 0.04 | 24 | 43 | 54 | 54 | 54 | 54 | 54 | 0.05 | 26 | 49 | 67 | 68 | 68 | 68 | 68 | 0.06 | 29 | 52 | 77 | 82 | 82 | 82 | 82 | 0.07 | 32 | 55 | 85 | 95 | 95 | 95 | 95 | 0.08 | 36 | 58 | 90 | 106 | 108 | 108 | 108 | 0.09 | 40 | 61 | 94 | 115 | 122 | 122 | 122 | 0.10 | 44 | 65 | 97 | 122 | 133 | 135 | 135 | 0.11 | 49 | 68 | 101 | 130 | 144 | 148 | 148 | 0.12 | 52 | 72 | 103 | 135 | 153 | 161 | 161 | 0.13 | 58 | 76 | 106 | 139 | 162 | 172 | 176 | 0.14 | 61 | 79 | 109 | 142 | 168 | 182 | 188 | 0.15 | 66 | 84 | 112 | 146 | 175 | 191 | 200 | 0.16 | 70 | 88 | 115 | 149 | 178 | 199 | 211 | 0.17 | 75 | 92 | 119 | 151 | 184 | 207 | 221 | 0.18 | 79 | 95 | 122 | 154 | 187 | 214 | 230 | 0.19 | 83 | 100 | 126 | 157 | 191 | 220 | 238 | 0.20 | 88 | 104 | 129 | 160 | 194 | 223 | 245 | 0.21 | 92 | 108 | 133 | 164 | 197 | 229 | 252 | 0.22 | 97 | 112 | 137 | 167 | 200 | 232 | 257 | 0.23 | 101 | 117 | 140 | 169 | 203 | 236 | 263 | 0.24 | 105 | 121 | 144 | 173 | 206 | 239 | 268 | 0.25 | 110 | 126 | 148 | 176 | 209 | 243 | 272 | 0.26 | 113 | 130 | 151 | 180 | 212 | 246 | 276 | 0.27 | 119 | 134 | 155 | 184 | 216 | 249 | 280 | 0.28 | 122 | 138 | 160 | 187 | 218 | 251 | 284 | 0.29 | 128 | 142 | 164 | 191 | 222 | 254 | 287 | 0.30 | 131 | 146 | 167 | 194 | 225 | 257 | 290 | 0.31 | 136 | 151 | 172 | 198 | 228 | 260 | 293 | 0.32 | 140 | 155 | 175 | 202 | 231 | 263 | 296 | 0.33 | 144 | 160 | 180 | 205 | 234 | 266 | 299 | 0.34 | 149 | 164 | 184 | 209 | 238 | 269 | 302 | 0.35 | 153 | 168 | 187 | 212 | 241 | 272 | 305 | 0.36 | 158 | 172 | 191 | 216 | 245 | 275 | 308 | 0.37 | 162 | 177 | 196 | 220 | 248 | 278 | 311 | 0.38 | 166 | 182 | 200 | 223 | 250 | 281 | 314 | 0.39 | 171 | 185 | 203 | 227 | 254 | 285 | 317 | 0.40 | 175 | 189 | 207 | 231 | 257 | 288 | 320 |
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Table 2—Chemistry Factor for Base Metals, °F
Copper, wt-% | Nickel, wt-% | 0 | 0.20 | 0.40 | 0.60 | 0.80 | 1.00 | 1.20 | 0 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 0.01 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 0.02 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 0.03 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 0.04 | 22 | 26 | 26 | 26 | 26 | 26 | 26 | 0.05 | 25 | 31 | 31 | 31 | 31 | 31 | 31 | 0.06 | 28 | 37 | 37 | 37 | 37 | 37 | 37 | 0.07 | 31 | 43 | 44 | 44 | 44 | 44 | 44 | 0.08 | 34 | 48 | 51 | 51 | 51 | 51 | 51 | 0.09 | 37 | 53 | 58 | 58 | 58 | 58 | 58 | 0.10 | 41 | 58 | 65 | 65 | 67 | 67 | 67 | 0.11 | 45 | 62 | 72 | 74 | 77 | 77 | 77 | 0.12 | 49 | 67 | 79 | 83 | 86 | 86 | 86 | 0.13 | 53 | 71 | 85 | 91 | 96 | 96 | 96 | 0.14 | 57 | 75 | 91 | 100 | 105 | 106 | 106 | 0.15 | 61 | 80 | 99 | 110 | 115 | 117 | 117 | 0.16 | 65 | 84 | 104 | 118 | 123 | 125 | 125 | 0.17 | 69 | 88 | 110 | 127 | 132 | 135 | 135 | 0.18 | 73 | 92 | 115 | 134 | 141 | 144 | 144 | 0.19 | 78 | 97 | 120 | 142 | 150 | 154 | 154 | 0.20 | 82 | 102 | 125 | 149 | 159 | 164 | 165 | 0.21 | 86 | 107 | 129 | 155 | 167 | 172 | 174 | 0.22 | 91 | 112 | 134 | 161 | 176 | 181 | 184 | 0.23 | 95 | 117 | 138 | 167 | 184 | 190 | 194 | 0.24 | 100 | 121 | 143 | 172 | 191 | 199 | 204 | 0.25 | 104 | 126 | 148 | 176 | 199 | 208 | 214 | 0.26 | 109 | 130 | 151 | 180 | 205 | 216 | 221 | 0.27 | 114 | 134 | 155 | 184 | 211 | 225 | 230 | 0.28 | 119 | 138 | 160 | 187 | 216 | 233 | 239 | 0.29 | 124 | 142 | 164 | 191 | 221 | 241 | 248 | 0.30 | 129 | 146 | 167 | 194 | 225 | 249 | 257 | 0.31 | 134 | 151 | 172 | 198 | 228 | 255 | 266 | 0.32 | 139 | 155 | 175 | 202 | 231 | 260 | 274 | 0.33 | 144 | 160 | 180 | 205 | 234 | 264 | 282 | 0.34 | 149 | 164 | 184 | 209 | 238 | 268 | 290 | 0.35 | 153 | 168 | 187 | 212 | 241 | 272 | 298 | 0.36 | 158 | 173 | 191 | 216 | 245 | 275 | 303 | 0.37 | 162 | 177 | 196 | 220 | 248 | 278 | 308 | 0.38 | 166 | 182 | 200 | 223 | 250 | 281 | 313 | 0.39 | 171 | 185 | 203 | 227 | 254 | 285 | 317 | 0.40 | 175 | 189 | 207 | 231 | 257 | 288 | 320 |
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