DEFENSE NUCLEAR FACILITIES SAFETY BOARD

November 14, 1994

MEMORANDUM FOR:                  G. W. Cunningham, Technical Director

COPIES:                          Board Members
                                 
FROM:                            R. Todd Davis

SUBJECT:                         Backup Power Working Group Meeting, Las Vegas,
                                 Nevada, Trip Report for October 18-20, 1994

1.    Purpose:  This memorandum reports the progress of the Backup Power Working
      Group (BPWG), which was established to explore ways to increase the
      reliability and availability of backup power supplies at DOE defense nuclear
      facilities.

2.    Summary:  Backup Power Supplies (BPSs) are installed at defense nuclear
      facilities to ensure safety-related loads (e.g., instrumentation and
      control, monitors, and ventilation systems) are operable after loss of
      offsite power.  A recently issued standard, DOE-STD-3003-94, provides the
      technical requirements for backup power supplies.  Although the groundwork
      has been established, there are still significant obstacles (e.g.,
      inadequate configuration control, equipment age and original design
      deficiencies) to providing reliable backup power at DOE facilities.

3.    Background:  In discharging its responsibilities, the BPWG is emphasizing
      the need for effective design, installation, operation, test and maintenance
      of backup power supplies at DOE facilities.  The group consists of several
      DOE representatives and many operating contractor employees.  

4.    Discussion/Observations:  The following issues were discussed at the BPWG
      meeting:

      A.    DOE-STD-3003-94, Backup Power Sources for DOE Facilities, has been
            issued.  DOE had previously issued a Defense Programs (DP) standard
            that provided guidance concerning design, installation, operation,
            testing and maintenance of backup power supplies; however, the standard
            only applied to DP facilities.  The new DOE standard will ensure that
            all DOE facilities, including Environmental Management (EM) facilities,
            have uniform guidance for backup power supplies.

      B.    Backup power for safety-related loads typically require proper
            operation of an Automatic Transfer Switch (ATS).  The ATS monitors the
            primary source of power and automatically switches to the secondary
            source, if available, upon loss of power.  For most ATS systems at DOE
            facilities, maintenance is difficult because there is  no method of
            deenergizing the ATS without deenergizing the associated safety-related
            loads.  Therefore, ATS maintenance is typically not performed.  ATS
            failure, due to inadequate maintenance, has been identified as a
            significant contributor to backup power failure at defense nuclear
            facilities.  The BPWG is requesting the Office of Nuclear Safety to
            issue a safety notice identifying ATS problems due to lack of
            maintenance.  The BPWG is also identifying system design changes which
            will allow ATS maintenance to be performed without deenergizing the
            associated loads.

      C.     In July 1994, the Office of Nuclear Safety at DOE issued a safety
            notice concerning diesel fuel contamination.  A DOE representative
            provided the background behind this safety notice and provided fuel
            sampling recommendations to ensure diesel fuel quality is acceptable. 
            Because diesel generators that provide backup power supply are operated
            infrequently, diesel fuel supply may remain in storage tanks for
            extended periods.  A diesel fuel sampling program is necessary to
            ensure generator fuel does not degrade.

      D.    The BPWG has committed to adopting a standard approach for measuring
            backup power reliability.  A subgroup is reviewing current practices
            and will recommend guidelines during the next meeting.  A standard
            approach for measuring reliability will allow comparison across the DOE
            sites and provide a tool for assessing site trends.

      E.    The BPWG is pursuing standardized purchase specifications for several
            components associated with backup power supplies (e.g., batteries,
            Automatic Transfer Switches (ATSs) and Uninterruptible Power Supplies
            (UPSs)).  Standardized purchase specifications will provide a technical
            baseline for procurement of BPS components.

      F.    The BPWG intends to develop a handbook for BPS systems (e.g., engines,
            generators, UPSs, ATSs and other support systems) that will provide
            detailed guidance for maintaining BPS systems.

      G.    Some requirements associated with the new DOE standard for BPSs are not
            realized by existing backup power systems at DOE facilities (e.g.,
            seismic/high wind protection, load sequencing and documentation).  The
            BPWG emphasized the importance of developing an implementation plan for
            the new backup power standard and of justifying deviations from the
            standard using a graded approach based on the safety significance of
            the facility electrical loads.

5.    Future Staff Actions:  The BPWG will meet every six months to discuss issues
      related to backup power systems.  The staff will continue to review the
      progress of the BPWG.  In addition, because of the importance of BPSs to
      defense nuclear facilities,  the staff is reviewing the adequacy of safety-
      related backup power systems across the complex.