Spring material and irradiation reference conditions
Process demonstration — unvalidated engineering estimates. Assumptions, transferred estimates and unresolved requirements remain explicit. This readable view does not change the source evidence.
Published reference material/history selected for the separate residual-preload estimate. The source file is an earlier proposal; the later checkpoint A basis adopted the explicitly provisional reference transfer. It does not predict an operating PWR assembly lifetime.
Published reference conditions
| Item | Definition or value |
|---|
| Alloy | Inconel X-750 |
| Form | Hot-rolled plate, rolling-direction specimens |
| Aging temperature (K) | 977 |
| Aging duration (h) | 24 |
| Irradiation environment | NRU flowing water |
| Fast neutron energy threshold mev | 1 |
| Fast flux range n m2 s | 1.5e+17; 1.8e+17 |
| Temperature k figure label | 573 |
| Temperature k body nominal | 570 |
| Restraint | Constrained bent beam, periodic unloaded-curvature observations |
| Fit | R(F) = 0.915 * exp(-1e-25 * F), F in n/m2; unrelaxed stress ratio |
| Fit uncertainty | No confidence interval or coefficient covariance established by this review |
ASSUMPTION — chosen exposure endpoint
| Item | Definition or value |
|---|
| Fast fluence (n/m²) | 6e+24 |
| Classification | Analyst-selected endpoint within the visually observed 573 K data span; not a separately reported test record |
| Temperature policy | Use the curve labelled 573 K, retain the source nominal 570 K wording; do not interpolate a temperature dependence from two curves. |
| Flux policy | Retain the source flux range. No detailed time-resolved irradiation schedule or shutdown history is claimed. |
| Applicability | NRU-reference exposure only. No PWR spectrum conversion or burnup-to-fluence equivalence is supplied. |
| Meaning of eol | End of the explicitly selected reference exposure, not an asserted reactor fuel lifetime |
Transfer assumptions
| Item | Definition or value |
|---|
| Cladding | Zircaloy-4, unchanged |
| Support material scope | Propose X-750 for the compliant spring/dimple surrogate; the actual shape/manufacturing equivalence to the tested plate is not established. |
| Initial forces n | Spring: 5; Dimple 1: 2.5; Dimple 2: 2.5 |
| Force mapping | For residual installed preload only, propose F_EOL = R(F_endpoint) * F_initial under fixed restraint and unchanged stress-to-force geometry. This transfer is an assumption, not a published grid-force result. |
| Stiffness mapping | Keep the supplied 50/20 N/mm effective tangents independent. Do not multiply the retained preload by 20/50 again. Derive endpoint unloaded interference from endpoint preload and its assigned tangent. |
| Bow history | Reference relaxation occurs at the installed restraint. Solve bow/contact subsequently as an endpoint load case. This does not predict simultaneous bow growth and irradiation relaxation. |
| Contact output | Report retained installed preload, bow-induced force change, and final unilateral contact force separately. A released contact carries zero force; later recontact is not negative retained preload. |
Source record and traceability
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Presentation generated from this retained record. Historical status fields describe the source revision; later review decisions are explained on the engineering review page.