Patent Number: 
Section: claims

1. A replacement thermal sleeve system comprising:a control rod drive mechanism (CRDM) comprising a head penetration adaptor, wherein the head penetration adaptor defines an entrance region, an exit region, and a shaft extending between the entrance region and the exit region, wherein the shaft comprises an inner diameter;a replacement thermal sleeve configured to replace an existing thermal sleeve situated in the head penetration adapter, the replacement thermal sleeve comprising:a base, wherein a central longitudinal axis extends through the base; andflanges extending from the base, wherein the flanges are disposed about the central longitudinal axis, wherein gaps are defined between the flanges, wherein each flange comprises a lug extending therefrom and a curved surface, and wherein the flanges are configurable in:a first configuration, wherein the lugs define a first diameter; anda second configuration, wherein the flanges are flexed toward the central longitudinal axis and the lugs define a second diameter, wherein the second diameter is less than first diameter and the inner diameter of the shaft; anda retention member comprising portions, wherein each portion is configured to engage the curved surface of one of the flanges to maintain the flanges in the second configuration prior to the replacement thermal sleeve entering the head penetration adaptor, and wherein the retention member is configured to release the flanges and allow the flanges to transition toward the first configuration, wherein the retention member is configured to maintain the flanges in the second configuration while the replacement thermal sleeve is moved inside the head penetration adaptor to an operational position, and wherein the retention member is configured to allow release of the flanges with the replacement thermal sleeve at the operational position. 2. The replacement thermal sleeve system of claim 1, wherein the flanges are configured to traverse the shaft from the entrance region toward the exit region in the second configuration. 3. The replacement thermal sleeve system of claim 2, wherein the flanges are configured to transition to the first configuration, based on the lugs exiting the shaft into the exit region. 4. The replacement thermal sleeve system of claim 3, wherein the exit region comprises a shoulder, and wherein the lugs are configured to engage the shoulder. 5. The replacement thermal sleeve system of claim 1, wherein each lug comprises a curved surface and a tapered surface, and wherein each tapered surface tapers toward the central longitudinal axis. 6. A system, comprising:a control rod drive mechanism (CRDM) comprising a head penetration adaptor, wherein the head penetration adaptor, defines:an entrance zone;an exit zone; anda shaft extending between the entrance zone and the exit zone, wherein the shaft comprises an inner diameter; anda replacement thermal sleeve configured to replace a thermal sleeve previously positioned in the head penetration adapter, comprising:a base, wherein a central longitudinal axis extends through the base; andflanges extending from the base, wherein flanges are disposed about the central longitudinal axis, wherein gaps are defined between flanges, wherein each flange comprises a head extending therefrom and a curved surface, and wherein the flanges are configurable in:a relaxed configuration, wherein the heads of the flanges define a first diameter; anda flexed configuration, wherein the flanges are flexed toward the central longitudinal axis and the heads define a second diameter, wherein the second diameter is less than first diameter and the inner diameter of the shaft; anda retention member comprising portions, wherein each portion is configured to engage the curved surface of one the heads to maintain the flanges in the flexed configuration prior to the replacement thermal sleeve entering the head penetration adaptor, wherein the retention member is configured to release the heads and allow the flanges to transition toward the relaxed configuration, wherein the retention member is configured to maintain the flanges in the flexed configuration while the replacement thermal sleeve is moved inside the head penetration adaptor to an operational position, and wherein the retention member is configured to allow release of the flanges with the replacement thermal sleeve at the operational position. 7. The system of claim 6, wherein flanges are configured to traverse the shaft from the entrance zone toward the exit zone in the flexed configuration. 8. The system of claim 7, wherein flanges are configured to transition to the relaxed configuration, based on the heads exiting the shaft into the exit zone. 9. The system of claim 8, wherein the exit zone comprises a shoulder, and wherein the heads are configured to engage the shoulder. 10. The system of claim 6, wherein each head comprises a curved surface and a tapered surface, and wherein each tapered surface tapers toward the central longitudinal axis. 11. A comprising:a control rod drive mechanism (CRDM) comprising a head penetration adaptor, wherein the head penetration adaptor defines an entrance region, an exit region comprising a shoulder, and a shaft extending between the entrance region and the exit region, wherein the shaft comprises an inner diameter;a replacement thermal sleeve configured to replace an existing thermal sleeve situated in the head penetration adapter, comprising:a base, wherein a central longitudinal axis extends through the base; andflanges extending from the base, wherein flanges are disposed about the central longitudinal axis, wherein gaps are defined between flanges, wherein each flange comprises a lug extending therefrom and a curved surface, wherein each lug comprises a curved surface and a tapered surface that tapers toward the central longitudinal axis, and wherein the flanges are configurable in:a relaxed configuration, wherein the curved surfaces of the lugs define a first diameter; anda flexed configuration, wherein the flanges are flexed toward the central longitudinal axis and the curved surfaces of the lugs define a second diameter, wherein the second diameter is less than first diameter and the inner diameter of the shaft;wherein flanges are configured to traverse the shaft from the entrance region toward the exit region in the flexed configuration;wherein flanges are configured to transition to the relaxed configuration, based on the lugs exiting the shaft into the exit region; anda retention member comprising engagement surfaces, wherein each engagement surface is configured to engage the curved surface of one the flanges and maintain flanges in the flexed configuration prior to the replacement thermal sleeve entering the head penetration adaptor, wherein the retention member is configured to release flanges and allow flanges to transition toward the relaxed configuration, wherein the retention member is configured to maintain the flanges in the flexed configuration while the replacement thermal sleeve is moved inside the head penetration adaptor to an operational position, and wherein the retention member is configured to allow release of the flanges with the replacement thermal sleeve at the operational position.