238.1. Subject to the provisions of section 238, failure by a person to assert his rights within the time prescribed by this Act shall deprive that person of the right to claim payment of the corresponding benefits out of the assets of the pension plan, unless that person shows, before the payment of the benefits of the affected members or beneficiaries begins, that it was impossible for him to act sooner or that he did not receive the information to which he was entitled under this Act for a reason outside his control.