安全英文論文1.pdf

John 7 Conway Chairman A J Eggenberger Vice Chairman DEFENSE NUCLEAR FACILITIES John E Mansfield SAFETY BOARD R Bruce Matthews 625 IndianaAvenue NW Suite 700 Washington D C 20004 2901 202 694 7000 June 12 2003 The Honorable Spencer Abraham Secretary of Energy 1000 Independence Avenue SW Washington DC 20585 1000 Dear Secretary Abraham The Defense Nuclear Facilities Safety Board Board and its staff have been evaluating the adequacy of the safety bases for the K Area Material Storage KAMS facility Building 235 F and FB Line at the Savannah River Site This review is part of an overall safety assessment undertaken in response to the Public Law 107 3 14 Section 3 183 Study of Facilities for Storage of Plutonium and Plutonium Materials at Savannah River Site In the enclosed report the Board s staff has identified several issues that require clarification or action by the Department of Energy DOE to ensure that these facilities will be adequate for their storage mission The Board is continuing to pursue the overall safety assessment mandated by Public Law 107 3 14 Section 3 183 but believes these issues merit near term DOE attention The presently defined mission and the associated safety bases for some of these facilities do not appear to be consistent with the long term storage activities planned by DOE In particular Building 235 F was anticipated to be shut down in the near future but now is planned to be used for long term storage and related operations Future activities will require significant new analysis and physical modifications to ensure safe operation as required by DOE directives Additionally the enclosed staff report notes 0 0 a Planned new conditions in KAMS will require the ventilation system to operate during certain fire scenarios in order to protect the public from exposures exceeding the evaluation guideline established by DOE The draft documented safety analysis however does not identify the ventilation system and associated systems as safety class consistent with DOE requirements The majority of the fire detection and alarm systems in all three facilities have been deactivated based in part on their expected short term mission Fire detection and alarm systems would normally be expected for defense in depth purposes consistent with DOE directives The risk from several hazards have been accepted rather than eliminated e g combustible inactive cables in KAMS and plutonium 238 contamination in Building 235 F The Honorable Spencer Abraham Page 2 The enclosed staff report discusses these issues in more detail Pursuant to 42 U S C Q 2286b d the Board requests a report within 60 days of receipt of this letter that informs the Board of actions or further evaluations that DOE may undertake on the above issues Sincerely c The Honorable Jessie Hill Roberson Mr Mark B Whitaker Jr Enclosure DEFENSE NUCLEAR FACILITIES SAFETY BOARD Staff Issue Report May 7 2003 MEMORANDUM FOR J K Fortenberry Technical Director COPIES Board Members FROM R Kasdorf SUBJECT Safety Bases Review of Plutonium Storage and Support Facilities at Savannah River Site In Public Law 107 3 14 Section 3 183 Study of Facilities for Storage of Plutonium and Plutonium Materials at Savannah River Site Congress tasked the Defense Nuclear Facilities Safety Board Board to conduct a study of the adequacy of the K Area Material Storage KAMS facility and related support facilities such as Building 235 F at the Savannah River Site SRS for the storage of defense plutonium and defense plutonium materials in connection with the Department of Energy DOE fissile materials disposition program This report documents a portion of the ongoing review being conducted by the Board s staff to evaluate the adequacy of the safety bases for this planned plutonium storage mission for KAMS Building 235 F and FB Line The DOE contractor at SRS either has submitted or is in the process of submitting documented safety analyses DSAs to the DOE Savannah River Operations Office DOE SR for these facilities to comply with Title 10 Part 830 of the Code of Federal Regulations 10 CFR Part 830 Nuclear Safety Management These safety bases do not account for some of the future activities that will be needed to support the planned long term storage mission Building 235 F is being studied for increased capacity for storing plutonium packaged in accordance with DOE STD 3013 Stabilization Packaging and Storage of Plutonium Bearing Materials addition of a plutonium stabilization and repackaging capability and limited sampling activities None of these activities are addressed in the approved Safety Analysis Report for Building 235 F The safety basis for FB Line does not reflect the plutonium oxide stabilization process being added although the staff expects that the existing safety basis controls will be sufficient Additionally the duration of the planned storage mission for KAMS significantly exceeds the 10 years originally expected DOE SR recognizes that the safety basis for these facilities must be changed to support the planned long term plutonium storage mission K Area Material Storage Facility The draft DSA for this facility has been submitted to DOE SR for approval The Board s staff reviewed this draft document since it was pertinent to the mission of the facility for long term storage of plutonium materials The facility is currently operating using a Basis for Interim Operation BIO as its safety basis The BIO does not authorize storage of the quantity of plutonium that would be required should DOE decide to consolidate all the excess plutonium from the DOE complex at SRS The draft DSA is based on a presumption that any material release in the facility has unacceptable consequences Accordingly the draft DSA requires plutonium to be stored in DOE STD 3013 containers enclosed in Type B shipping containers meeting 10 CFR Part 7 1 Packaging and Transportation of Radioactive Materials such as 9975 shipping containers The safety basis of this facility does not allow opening containers in the facility nor does it provide for any inspection of the contents other than for Material Control and Accountability which does not require container seals to be broken The event with the greatest offsite consequences is postulated to be a major fire that jeopardizes the integrity of the shipping containers potentially releasing plutonium to the environment The majority of the controls identified in the draft DSA relate to protection against such fires The fire thermal analysis performed in support of the draft DSA postulates two bounding fire scenarios that determine the safety controls l The first scenario is a fire on the 48 foot elevation which propagates to the Actuator Tower and into the Material Storage Area This fire scenario is credible due to the significant amount of combustible materials at this elevation primarily old abandoned cables Because the RAMS plutonium storage mission was expected to be of short duration DOE decided not to remove the combustibles and so eliminate the source of fire instead a 40 square foot hole vent was cut into the Actuator Tower roof to vent the tire The vent keeps the maximum temperature of the shipping containers below their qualified test temperatures Given current plans for a longer term storage mission the staff believes it would be more appropriate to prevent the fire by removing the combustibles l The second scenario is a fire in the Material Storage Area This tire scenario does not apply for the activities presently authorized for RAMS The draft DSA allows new conditions which are not authorized in the current BIO e g different forklifts which are not as robust nor explosion proof storage of an increased quantity of plutonium and alternate shipping containers SAFKEG which are insulated differently than the Type B 9975 shipping containers These new conditions result in the need to credit the ventilation system 903 fan to be operating during this event The fan draws air through the Material Storage Area to prevent the Type B shipping containers from exceeding their qualified temperatures during the fire The draft DSA however identifies only an air flow monitor as safety class equipment to be maintained by Technical Safety Requirement TSR level controls Furthermore the draft DSA does not provide adequate TSR level control for some identified safety significant equipment i e the 903 fan suction pressure gauge WSRC stated that a safety class ventilation system was not needed because the likelihood of a combined occurrence of a fire in conjunction with a loss of ventilation is incredible However the staff believes that the ventilation system 903 fan and its associated flow path should be identified as safety class to ensure adequate protection of the public consistent with DOE directives and WSRC requirements Building 235 F The safety basis for Building 235 F was prepared in 1989 using then applicable DOE requirements This document has been revised several times and was 2 supplemented by a hazard analysis performed in December 2002 The combined set was approved by DOE SR in January 2003 as a rule compliant DSA The original 1989 safety basis used Management Oversight Risk Tree methodology for identification and analysis of the hazards This approach is not consistent with the methodologies recommended by the safe harbor of 10 CFR Part 830 i e DOE STD 3009 94 Preparation Guide for Nonreactor Nuclear Facility Safety Analysis Reports nor is it consistent with current SRS standards Although this document was supplemented by a hazard analysis the combined safety basis is still based on a methodology that is inconsistent with the safe harbor because it does not analyze operational occurrence using a deterministic approach Instead a frequency based cutoff is used to screen out accident scenarios Additionally the unmitigated accident analysis used for identification and classification of safety controls calculates consequences using average or best estimate values of the parameters crucial to the dose estimates Finally the consequences to the public are calculated in terms of person rem as opposed to the maximum dose to a member of the public at the site boundary for unmitigated releases Presenting consequences in this manner was consistent with the DOE guidance in 1989 but is not consistent with current requirements provided in the safe harbor of 10 CFR Part 830 The fire suppression system in the facility has been deactivated and removed Only a small portion of the facility is covered by a tire detection and alarm system mainly the storage vaults During a walkdown in the facility the staff observed a significant amount of combustibles contaminated high efficiency particulate air filters plastic boxes and cables adjacent to a material storage vault Reducing or eliminating extraneous combustible materials in the facility would reduce the likelihood and consequences of a fire The staff was informed that a significant amount of plutonium 238 more than 700 grams is deposited in ducts or cells in the Plutonium Fuel Form facility and could be subject to release during a tire or seismic event The contractor considered the plutonium 238 holdup the most significant hazard in the facility Consideration should be given to decontaminating the areas with plutonium 238 holdup to reduce the risks associated with its potential release The ventilation system exhaust is designated as safety significant to confine airborne contaminants and direct them away from the facility workers As noted above there are many areas of the facility that are not covered by a tire detection and alarm system Workers would be notified of a fire in the facility by the alarm annunciation system However the facility s Fire Hazards Analysis identifies areas that are not covered by an audible alarm annunciation system i e the public address system The Nuclear Incident Monitors al