Urgent - Query Optimization

Hi,
I have a report which was taking 48 minutes. So I added rule hint in that now it is taking 14-15 min but, still it's not acceptable.. Is there any way I can elimintae these nested loops or Can I replace them with hash joins. or is there any other way to optimize this query. I don't have always_semi_join to hash_joins in the init.ora file and I don't want to set that in init.ora. Is there any session level setting like any rule which enforces the hash join.

Regards,
SELECT STATEMENT Optimizer=HINT: RULE
  SORT (UNIQUE)
    NESTED LOOPS

      NESTED LOOPS
        NESTED LOOPS
          NESTED LOOPS
            NESTED LOOPS
              NESTED LOOPS
                NESTED LOOPS
                  NESTED LOOPS
                    NESTED LOOPS
                      NESTED LOOPS
                        NESTED LOOPS
                          NESTED LOOPS
                            NESTED LOOPS
                              NESTED LOOPS
                                NESTED LOOPS
                                  NESTED LOOPS
                                    NESTED LOOPS
                                      NESTED LOOPS
                                        TABLE ACCESS (FULL) OF
TABLE_EMP_CERT
                                        TABLE ACCESS (BY INDEX ROWID) OF
TABLE_CERTIFICATION
                                          INDEX (UNIQUE SCAN) OF
CERTIFICATION_OBJINDEX (UNIQUE)
                                      TABLE ACCESS (BY INDEX ROWID) OF
TABLE_PART_CLASS
                                        INDEX (UNIQUE SCAN) OF
PART_CLASS_NAME_INDEX (UNIQUE)
                                    TABLE ACCESS (BY INDEX ROWID) OF
TABLE_EMPLOYEE
                                      INDEX (UNIQUE SCAN) OF
EMPLOYEE_OBJINDEX (UNIQUE)
                                  TABLE ACCESS (BY INDEX ROWID) OF
TABLE_PART_NUM
                                    INDEX (RANGE SCAN) OF
IND_PART_NUM2PART_CLASS (NON-UNIQUE)
                                TABLE ACCESS (BY INDEX ROWID) OF
TABLE_MOD_LEVEL
                                  INDEX (RANGE SCAN) OF
IND_PART_INFO2PART_NUM (NON-UNIQUE)
                              TABLE ACCESS (BY INDEX ROWID) OF
TABLE_SITE_PART
                                INDEX (RANGE SCAN) OF
IND_SITE_PART2PART_INFO (NON-UNIQUE)
                            TABLE ACCESS (BY INDEX ROWID) OF TABLE_CASE
                              INDEX (RANGE SCAN) OF IND_CASE_PROD2SITE_PART


(NON-UNIQUE)

                          TABLE ACCESS (BY INDEX ROWID) OF TABLE_SITE
                            INDEX (UNIQUE SCAN) OF SITE_OBJINDEX (UNIQUE)
                        TABLE ACCESS (BY INDEX ROWID) OF TABLE_ADDRESS
                          INDEX (UNIQUE SCAN) OF ADDRESS_OBJINDEX (UNIQUE)
                      TABLE ACCESS (BY INDEX ROWID) OF
TABLE_X_CASE_INFORMATION
                        INDEX (RANGE SCAN) OF CASE_OBJIDINDEX (NON-UNIQUE)
                    TABLE ACCESS (BY INDEX ROWID) OF TABLE_DEMAND_HDR
                      INDEX (RANGE SCAN) OF IND_DEMANDHDR_CASEINFO2CASE


(NON-UNIQUE)

                  TABLE ACCESS (BY INDEX ROWID) OF TABLE_DEMAND_DTL
                    INDEX (RANGE SCAN) OF IND_DEMAND_DTL2DEMAND_HDR


(NON-UNIQUE)

                TABLE ACCESS (BY INDEX ROWID) OF TABLE_CONDITION
                  INDEX (UNIQUE SCAN) OF CONDITION_OBJINDEX (UNIQUE)
              TABLE ACCESS (BY INDEX ROWID) OF TABLE_GBST_ELM
                INDEX (UNIQUE SCAN) OF GBST_ELM_OBJINDEX (UNIQUE)
            TABLE ACCESS (BY INDEX ROWID) OF TABLE_MOD_LEVEL
              INDEX (UNIQUE SCAN) OF MOD_LEVEL_OBJINDEX (UNIQUE)
          TABLE ACCESS (BY INDEX ROWID) OF TABLE_PART_NUM
            INDEX (UNIQUE SCAN) OF PART_NUM_OBJINDEX (UNIQUE)
        TABLE ACCESS (BY INDEX ROWID) OF TABLE_SITE
          INDEX (UNIQUE SCAN) OF SITE_OBJINDEX (UNIQUE)
      TABLE ACCESS (BY INDEX ROWID) OF TABLE_SITE
        INDEX (UNIQUE SCAN) OF SITE_OBJINDEX (UNIQUE)

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Author: 
  INET: Inder.Singh_at_gecits.ge.com

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