TRANSMITTED TO DOE/M. WHITAKER 04/19/95

DEFENSE NUCLEAR FACILITIES SAFETY BOARD

                                             January 9, 1995

MEMORANDUM FOR:     G. W. Cunningham, Technical Director

COPIES:        Board Members

FROM:               Ajit Gwal

SUBJECT:       Backup Power Supply Systems, Rocky Flats Environmental
               Technology Site, Report of Site Visit, September 27-29, 1994

     Purpose:  This memorandum provides a report of a visit by Defense Nuclear
     Facilities Safety Board (DNFSB) Staff members, Ajit Gwal and Todd Davis,
     to the Rocky Flats Environmental Technology Site (RFETS), Buildings 371,
     771, 707 and 779, on September 27-29, 1994.  The review focused on backup
     power supplies (i.e., Emergency Diesel Generators (EDGs) and
     Uninterruptible Power Supplies (UPSs)).  

     Summary:  The review identified the following major issues and
     observations:

      A.  For the RFETS facilities reviewed, significant improvements and
          upgrades in system design, maintenance and testing are required to
          achieve a high confidence level for reliable emergency power
          availability.  

      B.  The EDG in Building 779 is loaded to approximately 250% of the
          generator power capacity.  RFETS has administrative controls in
          place to prevent overloading the generator until the excess loading
          is removed.  

     C.   The Department of Energy (DOE) has taken steps toward improving the
          reliability of backup power systems with reports issued by an
          augmented evaluation team and a recently issued backup power supply
          standard.  However, cognizant personnel at RFETS were not aware of
          this information and have no direction to implement the
          improvements.

     D.   Lead-acid battery ventilation in most facilities at RFETS is
          inadequate.  Ventilation is necessary to prevent hazardous build-up
          of hydrogen gas.  There is currently no plan to upgrade the battery
          ventilation systems to meet the requirements of American National
          Standards Institute (ANSI) C2, National Electric Safety Code.

I.   Background:  Emergency power systems at RFETS provide power to ventilation
     exhaust, instrumentation and control and other vital safety systems during
     a failure of offsite power.  EDGs are required to accommodate emergency
     loads after approximately 10 to 50 seconds following a power failure. 
     EDGs supply power for an extended period.  UPSs use batteries to provide
     a continuous stable power supply during a power interruption; they  are
     required where the 10 to 50 second power interruption is unacceptable. 
     UPS only provides power for a short period, usually less than two hours.

II.  Discussion:

     A.   Generator Overloading:  The EDG in Building 779 is currently
          connected to loads that require approximately 250% of the generator
          power capacity.  A work order is in place to reduce these loads.  
          Except for informal hand calculations performed in 1978, loading
          calculations were not available for the EDG in Building 371.  For
          the EDG in Building 771, there is no load sequence, interlock or
          procedural requirement to prevent two exhaust fans from starting
          simultaneously which could exceed the generator capacity and result
          in a loss of emergency power.  Accurate emergency bus loading and
          sequencing information for all facilities should be available and
          utilized to prevent overloading and loss of emergency power.

     B.   Battery Ventilation:  ANSI C2, National Electric Safety Code,
          requires adequate ventilation and ventilation alarms for rooms with
          lead-acid batteries to ensure hydrogen does not build-up and result
          in an explosion.  All RFETS facilities reviewed do not have an alarm
          to detect a ventilation failure and do not conform to the
          requirements of ANSI C2.  In addition to having inadequate battery
          ventilation, Building 771 has a space heater located in the overhead
          above the batteries that provides an ignition source.  

     C.   DOE Standard:  Based on a large number of incidents where EDGs
          failed to provide a backup power supply, DOE formed an Augmented
          Evaluation Team (AET) to review the reliability and availability of
          EDGs.  The AET published its results in a November 1993 final
          report.  As a part of the AET review, a DOE standard, issued by
          Office of Defense Programs-DOE (DP) facilities (DOE-DP-STD-3003),
          which incorporates the knowledge gained during the AET review. 
          While the AET review included RFETS backup power systems, most
          personnel at RFETS were unfamiliar with the AET conclusions and the
          DOE-DP standard.  The AET review and DOE-DP standard contain
          important guidelines for ensuring that backup power supplies are
          available when needed (e.g., design, preventive maintenance and
          surveillance requirements and reference to applicable commercial
          standards).  This standard has recently been issued to establish
          fundamental requirements for backup power sources at all DOE
          facilities.

     D.   Drawing Control:  A one-line diagram of the Building 371 backup
          power system is posted in the utility control room and is used by
          operating personnel.  However, the diagram is not a controlled
          drawing.  RFETS personnel agreed the diagram should be a controlled
          drawing and are taking actions to correct the situation.

     E.   Starting System:  National Fire Protection Association (NFPA) 110,
          Emergency and Standby Power Systems, requires that the starting
          system be capable of three start cycles.  Most of the EDGs at RFETS
          are not tested to demonstrate this capability.

     F.   Load Test:  Both the U.S. Nuclear Regulatory Commission Regulatory
          Guide 1.9, Selection, Design, and Qualification of Diesel-Generator
          Units Used as Standby (Onsite) Electric Power Systems at Nuclear
          Power Plants; and DOE-STD-3003 require a 24-hour full load test
          every 18 months.  The EDGs at RFETS are typically exercised twice
          monthly (once fully loaded and once unloaded) for one hour. 
          Periodic demonstration of extended EDG operation is necessary to
          identify problems not observed during the one-hour tests.

     G.   Control System:  The control system for the EDG in Building 371 was
          manufactured before 1978 and uses mechanical relay devices to
          provide control signals to start the EDG during a power failure. 
          Failure of the control system has prevented the EDG from starting on
          several occasions in the last two years.  RFETS is considering a
          control system upgrade; however, a schedule has not been
          established.

     H.   Electrical Calculations:  Protective device coordination analysis
          has not been performed, except for Building 771.  Lack of
          coordination increases the number of components affected by a short
          circuit.  In addition, a review of the emergency breaker ratings
          compared with the available short circuit currents has not been
          done.  Both reviews are necessary to demonstrate an adequate
          emergency power system.

     I.   Redundant Systems:  A redundant and independent backup power supply
          provides increased emergency power system reliability.  RFETS
          facilities were not originally designed to provide redundant backup
          power supplies.  Two EDGs in Building 771 can each supply all
          emergency loads;  however, because the #2 EDG is located in a
          building which is not insulated or heated, the generator does not
          meet starting requirements during cold temperatures.  For the
          Building 707 emergency power supply system, two separate EDGs are
          required to supply the emergency loads.  Because the #2 EDG supplies
          emergency power for the #1 EDG control system, operator action is
          required to prevent failure of the #2 EDG from effecting the #1 EDG. 
          EG&G is currently in the process of upgrades in Building 707 needed
          to achieve a reliable redundant and independent emergency power
          system.

     J.   Preventive Maintenance:  The staff was told that there is no
          preventive maintenance performed on the EDG in Building 707.  A
          routine preventive maintenance program in accordance with NFPA 110,
          Standard for Emergency and Standby Power Systems, is essential to
          ensuring reliable emergency power to vital safety systems.

III. Future Staff Actions:  The DNFSB Staff intends to perform the following
     reviews to assess the progress of RFETS personnel in resolving the issues
     identified in this memorandum:

     A.   Progress of emergency power system upgrades.  Including
          implementation of recommendations contained in the DOE backup power
          review and the DOE backup power standard regarding design,
          preventive maintenance and testing.

     B.   Progress of reducing the generator loading for the EDG in Building
          779 and the load sequencing control for Building 771.

     C.   Resolution of lead-acid ventilation system inadequacies.

     D.   Progress of improvements in the EDG starting and control systems.

     E.   Protective device coordination and short circuit calculations for
          the emergency supply system.