The RCP 1 to CSR BC & OT 01 January 2023 release and associated Technical Background document (TB) are available via the following links:
RCP 1 (Fourth item on the following web page):
https://iacs.org.uk/publications/common-structural-rules/csr-for-bulk-carriers-and-oil-tankers/
Technical Background document (Fourth item on the following web page):
https://iacs.org.uk/publications/common-structural-rules/technical-background-documents-for-csr/