Sufficient evidence exists to determine that the DSA is kept up to date and has met annual update requirements.
Analysis
The Board determined that three DSA and TSR annual updates have been submitted by NWP and the previous contractor in the last four years. Annual updates are normally submitted around May of each year. Revisions 2 and 3 were submitted by the previous contractor in a timely manner, and CBFO approved them, documenting their approval in SERs. The DSA/TSR Revision 4 annual update was not approved for over a year due to multiple submittals of Revision 4, which raises the concern of a lack of priority being placed on updating the safety basis by both NWP and CBFO.
The following presents a history of safety basis changes made to the WIPP DSA and TSR during the periods covering 2008 to the present time. The DSA/TSR Revisions 0 through 4 were
approved during this time period and were selected for comparison because they represent a starting point in which a major safety basis upgrade was initiated, and because they show the evolution of changes made in the hazard/accident analysis and selected controls that occurred since the time of the initial upgrade.
The previous major upgrade to the DSA occurred in 2005 after a DOE Headquarters assessment of the CH DSA Revision 8 in 2004 concluded that improvements were necessary, especially with the DOE issuance of the DOE-STD-1186-2004, Specific Administrative Controls. This was considered to be a major step-up of the nuclear safety culture for WIPP and affected many operating and support procedures to implement the new TSRs.
The DSA/TSR Revision 0 was developed and approved in 2008 to implement the DOE-STD- 5506 issued in 2007, which provided a consistent approach for the hazard and accident analysis of TRU waste operations within the DOE complex, and selection of safety controls to prevent or mitigate accidents. The DSA/TSR Revision 1 was issued in 2009 to resolve some TSR
implementation issues identified with Revision 0. Implementation of the Revision 1 TSRs had a significant impact on the nuclear safety culture at WIPP, because it resulted from a major re- baselining of the hazard/accident analysis and led to a revision of numerous TSR implementing procedures and training to the new requirements.
The following changes to the DSA in the past few years have been limited to events involving a collapse of the back in a waste disposal room postulated in an active panel. This initial scope of the following discussion is chosen based on suspected events related to a radiation release event occurring in the U/G on February 14. Other DSA/TSR changes were made during this timeframe, but are not covered in this evaluation.
Revisions 0 and 1 of the DSA/TSR were approved in the 2008 and 2009 timeframe and represented a major upgrade of the safety basis. Among the U/G accidents evaluated in the DSA Section 3.3 hazard evaluation was Event 030-CH/RH-U/G, Roof Fall. The
unmitigated frequency/consequences of this event were judged to be an anticipated event with low consequences to the facility worker, high consequences to the co-located worker,
and moderate consequences to the public. The primary TSR control credited for this event was a SAC that required weekly ground control inspections to ensure changing conditions are promptly identified, evaluated and addressed. This reduced the frequency of a back/rib fall to unlikely, and lowered the consequence estimates to moderate for the co-located worker and low for the public. The conclusion of low facility worker consequences is the subject of one of two PISAs identified since the event happened.
Revision 2 of the DSA/TSR was approved in January 2011. The event number of Event 030-CH/RH-U/G, Roof Fall was changed to CH/RH-U/G-30-001a. No other changes were made to the unmitigated frequency/consequences or controls credited for the event.
Revision 3 of the DSA/TSR was approved in May 2011. Event CH/RH-U/G-30-001a was further changed in terms of the mitigated consequences to the maximally exposed off-site individual (increased from low to moderate) and a reduction in the frequency of the event from anticipated to unlikely. The reasons for these changes are unknown and are not discussed in the SER. These changes to the DSA/TSR (Revision 2) were made by the contractor, reviewed by CBFO nuclear safety and approved by the acting CBFO Manager as the delegated SBAA. These changes were not recognized by CBFO during their review, and therefore, the basis for the changes were not discussed in the DOE’s Safety Evaluation Report (SER).The previous SAC control was also removed and presented as an initial assumption/initial condition of the analysis. This reduced the unmitigated frequency of the event, which is not consistent with the unmitigated analysis guidance in DOE-STD-3009 and DOE-STD-5506. However, the initial assumption/condition is not protected as a TSR control.
Revision 4 of the DSA/TSR was approved in August 2013. Event CH/RH-U/G-30-001a was significantly changed in Revision 4. The event title and location was changed to a
Roof Fall in a Closed Panel. DSA Revision 4 no longer evaluates an accident involving a
roof fall in an active panel. The revised event also had significant changes in frequency and consequence. The unmitigated and mitigated frequency is changed to “anticipated.” Both unmitigated and mitigated consequences are also reduced to low for all receptors. Through interviews, NWP Nuclear Safety acknowledged it was in error for not including the hazard scenario, i.e., event #CH/RH-U/G-30-001b, from the WIPP-021 hazard analysis report in the DSA. This change was not identified by CBFO during their review, and therefore, the basis for the change was not provided in the DSA or DOE’s Safety
Evaluation Report (SER). It is not clear in the DSA or the CBFO SER why this change is justified.
CON 2: There has been a reduction in conservatism in the Documented Safety Analysis
hazard/accident analysis and Technical Safety Requirement safety controls within safety basis revisions occurring since 2010, i.e., Documented Safety Analysis/ Technical Safety
Requirement, Revision 1 to Revision 4. This is not consistent with DOE-Standard (STD)-
3009, Preparation Guidance for U.S. Department of Energy Nonreactor Nuclear Facility
Safety Analysis and DOE-STD-5506, Preparation of Safety Basis Documents for Transuranic (TRU) Waste Facilities.
JON 3: NWP needs to revise the hazard and accident analyses to comply with DOE-Standard-
3009, Preparation Guidance for U.S. Department of Energy Nonreactor Nuclear Facility
Safety Analysis and DOE-STD-5506, Preparation of Safety Basis Documents for Transuranic (TRU) Waste Facilities, regarding not crediting administrative controls in the unmitigated
analysis. In particular, some initial assumptions/initial conditions, e.g., compliance with 30 CFR 57, Safety and Health Standards Underground Metal and Nonmetal Mines ground control program requirements, should be preventive or mitigative controls derived by the mitigated analysis and should be evaluated for the need for protection with Technical Safety Requirement controls.