Editing Seabee (section)

===Nuclear tests===
[[File:Seabees build camera tower on Bikini Atoll.jpg|thumb|The 53rd CB erecting camera towers on Bikini Atoll for filming the tests.]]
In early 1946 the 53rd NCB was deployed with [[Operation Crossroads]] for the [[nuclear testing at Bikini Atoll]].<ref>{{cite book |url=https://books.google.com/books?id=cI7rEUDQ6lEC&pg=PA470|title=Building the Navy's Bases in World War II: History of the BuDocks and the CEC 1940–1946 |volume=II |publisher=U.S. GPO|location=Washington, DC |date=1947 |page=416 |access-date=18 October 2017}}</ref> It was designated Task Unit TU 1.8.6.<ref>{{Cite web|url=https://www.history.navy.mil/content/history/nhhc/research/library/online-reading-room/title-list-alphabetically/o/operation-crossroads/composition-of-joint-task-force-one.html|title=Composition of Joint Task Force One|website=NHHC|accessdate=May 11, 2022}}</ref> 53's project list included observation, instrument and communication towers, [[radio beacon]]s, seismic huts, photo reference crosses, general base and recreational facilities, as well as [[dredging]] the [[lagoon]]. In addition, recreational facilities were constructed on Japtan Island for the ships crews of the Operation. The Battalion also assisted the relocation of the natives. They disassembled both the Community center and church for reassembly on [[Rongerik Atoll]]. In August the battalion was decommissioned with men transferred to CBD 1156 that was then commissioned on Bikini.<ref>{{Cite web|url=http://www.dtra.mil/Portals/61/Documents/NTPR/2-Hist_Rpt_Atm/1946_DNA_6032F.pdf|title=Operations Crossroads, DNA 6032F, prepared by the Defense Nuclear Agency, pp. 190–91|accessdate=May 11, 2022|archive-date=25 March 2021|archive-url=https://web.archive.org/web/20210325000914/https://www.dtra.mil/Portals/61/Documents/NTPR/2-Hist_Rpt_Atm/1946_DNA_6032F.pdf|url-status=dead}}</ref> The TU 1.8.6 designation transferred to the CBD. CBD 1156 remained for nine days after the second test.<ref name="Rottman224">{{cite book |title=U.S. Marine Corps World War II Order of Battle: Ground and Air units in the Pacific War, 1939–1945 |url=https://archive.org/details/usmarinecorpswor00rott |url-access=limited |first=Gordon L. |last=Rottman |location=Westport, CN |publisher=Greenwood Press |year=2002 |page=[https://archive.org/details/usmarinecorpswor00rott/page/n238 224] |isbn=9780313319068 }}</ref><ref>{{cite web |url=http://seabeemagazine.navylive.dodlive.mil/2017/07/30/this-week-in-seabee-history-week-of-july-30-august-5/ |first=Frank A. |last=Blazich |title=This Week in Seabee History (Week of July 30 - August 5) |date=30 July 2017 |website=Seabees Online |publisher=Navy Facilities Engineering Command |access-date=18 October 2017 |archive-date=7 August 2017 |archive-url=https://web.archive.org/web/20170807023659/http://seabeemagazine.navylive.dodlive.mil/2017/07/30/this-week-in-seabee-history-week-of-july-30-august-5/ |url-status=dead }}</ref>

UDT 3 was designated TU 1.1.3 for the operation. On 27 April 1946, seven officers and 51 enlisted embarked at CBC Port Hueneme for Bikini.<ref>{{Cite web|url=http://www.dtra.mil/Portals/61/Documents/NTPR/2-Hist_Rpt_Atm/1946_DNA_6032F.pdf|title=Operations Crossroads, DNA 6032F, prepared by the Defense Nuclear Agency, p. 189|accessdate=May 11, 2022|archive-date=25 March 2021|archive-url=https://web.archive.org/web/20210325000914/https://www.dtra.mil/Portals/61/Documents/NTPR/2-Hist_Rpt_Atm/1946_DNA_6032F.pdf|url-status=dead}}</ref> Their assignment was to retrieve water [[sample (material)|sample]]s from [[ground zero]] of the Baker blast. In 1948, the displaced bikinians put in a request that a channel to the island [[Kili Island|Kili]] where they had been relocated be made. This was given to the Seabee detachment on Kwajelin who requested UDT 3 assist.

The 121st CB was decommissioned in December and re-designated CBD 1504.<ref>[https://www.history.navy.mil/content/dam/museums/Seabee/UnitListPages/CBD-Post-WWII/CBD%201504.pdf Naval Construction Battalion Detachment 1504 file, Seabee Museum Archives, Port Hueneme, CA.]</ref> In January 1947 CBs 104 and 105 were reactivated. The 30th NCR was home-ported on Guam composed of CBDs 1501-13 and NCB 103. In 1949, the 103rd was made a Mobile Construction Battalion (MCB) while CBs 104 and 105 were made Amphibious Construction Battalions(ACBs). From 1949 until 1968 CBs were designated MCBs. In 1949, MCB 1 was reactivated at Naval Amphibious Base Little Creek, VA. In June 1950 the NCF totaled a few thousand.