An insurer issuing the standard policy pursuant to section 26.1-39-06 may affix to the policy or include in the policy a written statement that the policy does not cover loss or damage caused by nuclear reaction or nuclear radiation or radioactive contamination, all whether directly or indirectly resulting from an insured peril under the policy. An insurer may attach to the standard policy an endorsement or endorsements specifically assuming coverage for loss or damage caused by nuclear reaction or nuclear radiation or radioactive contamination.