TRANSMITTED TO M. WHITAKER 07/26/95

DEFENSE NUCLEAR FACILITIES SAFETY BOARD                                                               
              

February 17, 1995

MEMORANDUM FOR:       G. W. Cunningham, Technical Director

COPIES:               Board Members

FROM:                 C. H. Keilers, Jr.

SUBJECT:              Device Assembly Facility Review

1     Purpose:  This trip report documents a review of the status, safety basis, safety and
       electrical systems, and fire protection for the Device Assembly Facility (DAF) at the Nevada
       Test Site (NTS).  The review was performed on February 7-9, 1995, by T. Davis, A. Gwal,
C.
       Keilers and C. Martin of the Defense Nuclear Facilities Safety Board (Board) technical
       staff.

2.     Summary:    The DAF is a new, moderate hazard facility for nuclear explosive operations.
       An integrated Nuclear Explosive Safety Study (NESS) is anticipated in June 1995, followed
       by an Operational Readiness Review (ORR) in August 1995.  Although originally intended
for
       assembling one-of-a-kind devices, the DAF mission has the potential to evolve to a broader
       range of operations.  Additional missions may include assembly, disassembly, modification,
       staging, maintenance, repair, retrofit, and surveillance of nuclear weapons.  The staff is
       continuing to follow DAF preparations.

3.     Background:  The DAF was designed 10 years ago to consolidate NTS nuclear explosive
       operations and to replace aging facilities that are closer to the public and have fewer
       safety features.  Construction started in 1988 and is now nearing completion.  The facility
       consists of about two dozen independent buildings connected by a corridor and buried in a
       hillside.

4.     Discussion:  DOE, laboratory, site contractor, and consulting personnel briefed the staff
       on NESS/ORR preparations, as well as the DAF safety basis, safety and electrical systems,
       and fire protection.  The staff has the following key comments and observations (other
       observations are included in the attachment):

       a.      Although originally intended for assembling one-of-a-kind nuclear test devices, the
               DAF mission has the potential to evolve to a full range of nuclear explosive
               operations.  This is already reflected in the DAF Environmental Assessment, recently
               submitted to the state of Nevada.  The Final Safety Analysis Report (FSAR) is also
               being revised to reflect the other potential missions.

       b.      The proposed DAF organization includes a permanent facility management team and
               temporary laboratory project teams that report up a different chain of command.  This
               organization has been used successfully before for assembling unique test devices
               (i.e., for research).  However, it may need to be reevaluated as the DAF mission
               evolves.  In particular, a single chain of command may be more appropriate if the
               future mission includes operations comparable in scope to those at Pantex.

       c.      At NTS, the NESS and the FSAR are still two relatively independent activities
               described as "ratcheting" each other.  This is different from Pantex which is adopting
               a "seamless" philosophy recommended by the Department of Energy (DOE) Nuclear
               Explosive Safety Study Final Report (April 1994).  It is not evident that the Pantex
               process is being imported into NTS.

       d.      The FSAR for DAF is based on a 25 Rem evaluation guideline for dose to the public
               following postulated accidents.  The staff is still reviewing a separate DOE proposal
               to use 25 Rem across the complex as the evaluation guideline for such postulated
               events.

       e.      DAF has certain capabilities that DOE no longer intends to use and that are outside
               the safety envelope described in the draft FSAR (e.g., certain features in the 305
               cell and 351 high bay).  It would be worthwhile to clearly identify all such
               capabilities in the FSAR and thereby assist facility management in performing
               Unreviewed Safety Question (USQ) determinations if those capabilities are later
               needed.

       f.      Ventilation in the DAF battery room is inadequate to prevent buildup of hydrogen gas. 
               DAF personnel stated that the batteries will be replaced in October 1995 with
               "maintenance free" batteries.  The staff observes that even "maintenance free"
               batteries may still require some maintenance to eliminate any potential for explosion. 
               The staff will follow this effort.

       g.      Studies on protective device coordination have recently been performed for the DAF
               electrical distribution system; however, the studies do not include the emergency
               distribution system.  Coordination of the emergency distribution system is necessary
               to ensure backup power is available and reliable during a loss of normal power.

       h.      DAF does not appear to have any personnel familiar with the design details of the
               electrical distribution system.  A qualified electrical engineer is needed to ensure
               safe operation of the electrical distribution system during abnormal situations and
               to ensure equipment maintenance and replacement are performed adequately.

       i.      DAF has not performed a fire hazard analysis (FHA) in accordance with DOE Orders
               6430.1A and 5480.7A.  DAF personnel believe that the substance of a FHA has been
               developed but has not been consolidated into a FHA format.  Such analysis is necessary
               to demonstrate facility fire hazard adequacy.

5.     Future Planned Activities:  The staff is still reviewing key DAF analyses and will
       separately update its plan for following DAF preparations for operation.



























Attachment
Board Staff Review of the Device Assembly Facility
February 7-9, 1995

I.     Introduction:  This attachment provides additional and augmented staff comments and
       observations on the status, safety basis, safety and electrical systems, and fire protection
       for the Device Assembly Facility (DAF) at the Nevada Test Site (NTS).

II.    Facility Description:  

       The facility consists of about two dozen independent buildings, all connected by a corridor
       and buried in a hillside (i.e., cut and cover construction).  The buildings include five
       assembly cells with gravel gerties, seven assembly or high bays, two radiography rooms,
       several bunkers, and an administration building.  DAF was designed so that, if an explosion
       were to occur in one building, workers in other buildings would be protected from blast,
       missiles, and spreading contamination.  By design, this level of protection does not extend
       to corridors connecting buildings or to the shipping/receiving areas.

       Most assembly operations will be done in the cells and bays.  The assembly cells are the
       only facilities in which bare conventional high explosives (HE) and special nuclear
       materials (SNM) are collocated.  The cell safety systems include gravel gerties, resilient
       flooring, blast valves, and redundant blast doors.  The redundant doors are interlocked so
       that at least one door is closed at all times when explosive operations are underway.

       The assembly bays and high bays can be used for operations involving SNM and less sensitive
       explosives (i.e., encased HE and encased or bare IHE).   The bay safety systems include
       resilient flooring and blast doors.  Unlike the assembly bays, the high bays do not have
       redundant equipment blast doors and will require more operational controls.

       DAF Operational Safety Requirements include mass limits on HE/SNM for each facility, as
well
       as restrictions on operations if safety systems are nonfunctional.  Resilient flooring is
       to be installed in all HE handling areas.  No HE machining is permitted anywhere in DAF.

III.   Board Staff Comments and Observations:  

       1.      Mission:  Historically, nuclear test devices were assembled at either the Able or
               Baker facilities in Area 27.  The DAF was designed to consolidate test device assembly
               in one facility that would also have upgraded safety features.  The DAF Environmental
               Assessment, recently submitted to the state of Nevada, indicates that the DAF mission
               may extend beyond just test device assembly to also potentially include assembly,
               disassembly, modification, staging, maintenance, repair, retrofit, and surveillance
               of nuclear weapons.  The staff is closely following anticipated FSAR changes that will
               reflect the evolving mission.

       2.      Management:  The DAF management organization is based on that used before at the
Able
               and Baker facilities.  The organization includes a permanent facility management team
               and a temporary project team associated with each unique test device.  These teams
               report up different chains of command, and each has a responsibility for ensuring safe
               facility operation.  This organization has been appropriate in the past when NTS
               activities were focused on laboratory research involving one-of-a-kind test devices. 
               However, the staff is concerned that this management structure may dilute the lines
               of responsibility if the DAF mission evolves to the scale of nuclear explosive
               operations at Pantex.

       3.      FSAR-NESS Interaction:  DAF personnel are developing the FSAR and the NESS
               independently.  Where the requirements of the two activities overlap, the most
               restrictive or conservative requirement will be used by the facility.  

               This process is different than the approach adopted by Pantex which integrates the
               two activities based on a "seamless" safety philosophy, as recommended in the DOE
               Nuclear Explosive Safety Study Final Report (April 1994) and referred to as the
               "Stockpile Stewardship 21" (SS 21) initiative.

               The DOE Nuclear Explosive Safety Study Final Report also recommended that
DOE/NV
               closely monitor the Pantex SS 21 effort and import applicable portions into NTS
               operations.  Although DOE/NV may be monitoring the Pantex effort, it is not evident
               that any of the Pantex process is being transferred to NTS.  Furthermore, although
               the FSAR places a high reliance on individual training and qualification, the NESS
               process is not explicitly set up to evaluate these aspects.

       4.      Procedures:  Much work remains to prepare all the necessary procedures required to
               operate the DAF, particularly for laboratory, planning for maintenance, configuration
               management, high explosive safety, and industrial safety, health, and fire protection.

       5.      Order Compliance:

               a.     DAF has trained personnel to perform self-assessments for administrative order
                      compliance.  Letter assessments were completed for two orders ,.  Applicable
                      requirements in 51 remaining DOE orders are currently being assessed and
                      documented in the Standards/Requirements Identification Database (STRIDE). 
The
                      facility intends to submit their assessment to DOE/NV in March 1995.

               b.     DAF was designed to an earlier version of the DOE General Design Criteria (DOE
                      Order 6430.1), and subsequently, an outside contractor (UE&C) performed a
                      requirement-by-requirement assessment of the facility to the latest revision
                      (DOE Order 6430.1A).  The DAF management next formed a backfit review
committee
                      to assess the several hundred deviations from the latest version and to make
                      recommendations based on cost and safety implications.  The staff observes that
                      the backfit committee addressed several safety-related deviations by
                      referencing the draft FSAR; however, the draft FSAR does not explicitly
                      identify these as DOE Order deviations, which may be worthwhile.  The staff is
                      still reviewing the backfit committee recommendations for safety-related
                      requirements.  

       6.      Configuration Management:  DAF management reported that facility drawings and
               documentation frequently do not reflect the as-built facility.  Effort is underway
               to remedy this.  The primary cause appears to be that much of the DAF construction
               was under contract management by the U. S. Army Corps of Engineers and the
subsequent
               turnover to the Department of Energy was not well executed.  The staff is concerned
               that the existing situation may be exacerbated by the facility/project team management
               organization discussed above.

       7.      Safety Basis:  

               a.     Even though the draft FSAR was done to an earlier DOE safety analysis order ,
                      it appears to cover the key technical areas described in the current order . 
                      DOE has not yet approved the FSAR.  The staff anticipates some changes and will
                      review those changes as they become available. 

               b.     The current DAF plan for addressing the evolving mission is to use the
                      Unreviewed Safety Question (USQ) determination process.  DAF management
                      anticipates that the risks in the evolving mission will be lower than those for
                      assembling one-of-a-kind experiments.  The staff expects that the risk impact
                      will need to be systematically evaluated as the mission becomes better defined. 
                      

               c.     The original design of the DAF included additional capabilities which are not
                      described in the FSAR (e.g., certain design features in the 305 cell and 351
                      high bay).  These capabilities may be required for possible new DAF mission
                      requirements.  The staff believes that such capabilities should be described
                      in the FSAR to assist in resolving Unreviewed Safety Question determinations
                      if those capabilities are later needed.

               d.     Certain operations are also outside the FSAR safety envelope, such as HE
                      machining or high corridor occupancy during nuclear explosive operations.  Most
                      of these are obvious.  However, the staff believes that a systematic approach
                      needs to be taken to ensure all these restrictions are captured in DAF
                      administrative controls. 

               e.     The draft FSAR evaluates a full range of postulated accident scenarios,
                      presents public doses, and compares those doses to a 25 Rem evaluation
                      guideline.  The projected 50-year doses to the maximally exposed off-site
                      individual are below the evaluation guideline and range from 25 mRem for a
                      small detonation in a cell (deemed unlikely) to 10 Rem for a large detonation
                      in a bay (deemed incredible). 

                      DOE has not yet provided approved direction on evaluation guidelines for
                      postulated accident exposures to the public.  The staff is separately reviewing
                      a DOE proposal to use 25 Rem as the evaluation guideline across the DOE
                      complex.

               f.     Unlike the Pantex design, the DAF blast valves are a simpler, less-costly,
                      nonlatching design that will release more SNM after the initial blast.  The
                      staff is still reviewing the tradeoffs that were made to arrive at this design.

       8.      Electrical Systems:

               a.     Battery Ventilation:  Lead-acid batteries at the DAF are not adequately
                      ventilated in accordance with the ANSI C2, National Electric Safety Code. 
                      Inadequate ventilation could allow hazardous buildup of hydrogen gas and
                      subsequent explosion.  

                      DAF personnel stated that the batteries will be replaced in October 1995 with
                      "maintenance free" batteries that release only a small amount of hydrogen.  In
                      the meantime, the facility will need to periodically monitor the battery room
                      to detect any hydrogen accumulation.

                      "Maintenance free" batteries are not entirely maintenance free.  They still
                      require some maintenance to eliminate any potential for explosion, such as
                      periodically torquing battery terminals to detect loose connections.  The staff
                      will continue to follow the battery replacement program and any ventilation
                      design modifications.

               b.     Electrical Calculations:  The facility electrical design calculations were
                      performed in 1987 by  Raytheon Service Nevada (RSN).  However, during a
                      facility review it was identified that the protective device coordination
                      studies, in accordance with IEEE 242, "IEEE Recommended Practice for
Protection
                      and Coordination of Industrial and Commercial Power Systems," have not been
                      performed.  Subsequently, these studies were performed by RSN in 1994.  Based
                      on these calculations, approximately $100,000 dollars in electrical upgrades
                      have been identified and will be performed to correct facility deficiencies. 
                      Staff review of these recent calculations identified that the coordination
                      studies for the emergency distribution system were not performed.  DAF
                      personnel stated that a coordination of the emergency buses will be
                      accomplished.

                      During a review of the short circuit calculations performed in 1987, the staff
                      noted that the short circuit currents identified in the calculations appeared
                      to exceed some of the component specifications.  DAF personnel stated that
                      components in the facility electrical distribution  system  may have changed
                      since 1987.  Based on the potential changes and because the electrical
                      distribution system components have already been identified and entered in a
                      software program for the coordination studies, DAF personnel stated that they
                      would recalculate the short circuit currents and compare the calculations with
                      the equipment short circuit ratings.  Short circuit currents exceeding the
                      equipment short circuit ratings could result in an electrical fire or
                      explosion.

               c.     Facility Electrical Support:  RSN personnel, associated with DAF construction,
                      located the original design calculations and presented them to the staff. 
                      However, nobody was familiar with the facility electrical distribution design. 
                      For example, DAF personnel presented the backup diesel generator system as a
                      redundant system with two diesel generators.  After reviewing the design
                      documentation, it was determined that the generators were intended to be
                      operated in parallel and have only approximately 13% load margin.  In addition,
                      one-line drawings presented in the FSAR were not consistent with the facility
                      design.  A cognizant engineer for the DAF electrical systems is needed to
                      provide guidance during abnormal situation and ensure equipment maintenance and
                      replacement are adequately reviewed.

               d.     Oil Insulated Transformers:  Two oil-insulated transformers located inside the
                      DAF structure are parts of the facility power distribution system.  The
                      transformer oil provides cooling for the transformer.  Because the oil is
                      flammable,  it is a fire hazard if the transformer leaks or fails
                      catastrophically.  The National Electrical Safety Code and National Fire
                      Protection Association (NFPA) 70, National Electric Code, require indoor oil-
                      insulated transformers be located in a transformer vault.  The code
                      requirements for the transformer vault include fire walls and doors,
                      ventilation and oil containment.  The room did not appear to have the required
                      fire walls.  DAF personnel are reviewing the room design and will inform the
                      staff as to the design.

               e.     Lightning Protection:  DAF has designed the lightning protection system in
                      accordance with NFPA 780.  The system has been fully installed and tested to
                      ensure all terminals are properly grounded.  In addition, a lightning detection
                      system will be installed in the facility that interfaces with remote
                      electromagnetic detectors which detect the presence of lightning storms and
                      will allow the facility to cease work.  Details of the lightning protection and
                      detection system will be included in the electrical phenomena report which is
                      scheduled to be issued in July 1995.

               f.     Single Point Failure:  The NTS electrical distribution system can receive power
                      from two separate power generation plants.  However, the NTS site distribution
                      system is fed on a single line to the DAF and other facilities.  This above
                      ground distribution system has been damaged and power has been unavailable for
                      extended periods several times in the past.

               g.     DAF Distribution System:  During meetings within the DAF, the facility lighting
                      system would dim periodically and the gradually become brighter.  The facility
                      personnel were not sure what was causing the deficiency.  Reduction in the
                      facility light intensity indicates that the facility distribution system may
                      be near its electrical loading capacity.  Because facility loads tend to grow
                      over time, the staff believes that this situation should be evaluated and
                      corrected.
               
       9.      Fire Protection:

               a.     Fire Hazard Analysis:  A Fire Hazard Analysis (FHA), which is required by DOE
                      Orders 6430.1A and 5480.7, provides an analysis of the hazards associated with
                      a facility fire.  This document is essential in determining whether adequate
                      fire prevention, detection and suppression systems have been implemented. 
                      Although DAF personnel believe that the substance of a FHA has been developed
                      for the facility, this material has not been consolidated into FHA format.

               b.     Seismic Qualification of Emergency Lighting:  DAF personnel were unsure
whether
                      the emergency lighting system (e.g., UPS and lights) were seismically
                      qualified.  These lights are necessary for safe egress following an earthquake. 
                      DAF personnel will review the system design and inform the staff as to the
                      emergency lighting system capability following a seismic event.