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Resolution of Generic Safety Issues: Issue 175: Nuclear Power Plant Shift Staffing (Rev. 1) ( NUREG-0933, Main Report with Supplements 1–35 )


Historical Background

The NRC post-TMI-2 accident shift staffing policy was codified through the issuance of 10 CFR 50.54(m) which specified minimum requirements for licensed operators at nuclear power reactor sites but not for non-licensed personnel. Subsequently, the NRC promulgated additional shift staffing requirements and specified actions required by certain plant personnel during an emergency. These include personnel requirements for fire brigades and emergency response personnel contained in Appendix R and Appendix E to 10 CFR 50, respectively, and the shift staffing implications commensurate with the reporting/notification requirements contained in 10 CFR 50.73 and 10 CFR 72. In addition, Generic Letter 86-041650 encouraged licensees to combine one of the required Senior Reactor Operator (SRO) positions with the Shift Technical Advisor (STA) position forming a dual role position (SRO/STA).

Subsequent events over the last several years at some nuclear power plants have led to questions regarding the adequacy of the shift staffing level requirements. In particular, concern was raised regarding the minimum shift staffing (including non-licensed personnel) needed during an event which challenges a backshift crew's ability to perform all necessary functions.

Information Notice (IN) 91-771651 was issued to alert licensees to the problems that could result from inadequate control of shift staffing levels. IN 91-771651 identified fire brigade and security response as additional duties that some licensees had assigned to operations staff, and reminded licensees that 10 CFR 50.54(m) specifies only minimum staffing levels for licensed operators and does not address personnel availability for all of the necessary actions specified in the licensees' administrative controls and required by an event.

In NUREG-1275,1079 Volume 8, concerns were raised regarding the use of STAs to perform duties during plant events that may interfere with their ability to perform their primary function of providing engineering and accident assessment advice to the shift supervisor. NRR completed a survey of licensee staffing practices, including how plant personnel were distributed, to ensure necessary actions could be accomplished during an event.

NUMARC provided1655 the NRC with the results of its survey of industry staffing practices; this survey documented responses from 110 of the 113 licensees solicited. Ninety-three percent of the respondents stated that they conducted a staffing review after receiving IN 91-771651; the 7% that did not respond had recently conducted a shift complement staffing study. Some licensees increased staffing to accomplish required tasks, reassigned duties to more evenly distribute the workload, or modified equipment to reduce the need for operator action. All respondents confirmed the adequacy of their existing staffing practices against the two actual occurrences cited in IN 91-77.1651

Information Notices 93-441652 and 93-811653 were issued to alert the industry to the operational challenges that could result when responding to an event with minimum staffing levels, or when STAs are distracted from their accident assessment duties by serving in concurrent roles such as fire brigade leader or communicator. NRR requested RES to evaluate the adequacy of the minimum staffing levels required by 10 CFR 50.54(m). The staff also issued two reports to the Commission: (1) SECY-93-1841656 informed the Commission that an NRR survey indicated operators at some plants were concerned about the adequacy of their staffing to handle certain complex events, and several AEOD event reviews indicated that shift resources had not been effectively allocated to ensure that individuals were not overburdened; and (2) SECY-93-1931657 summarized the staff's findings concerning the industry's implementation of the STA position at nuclear power plants. The staff found that the STA was an on-call position at 20 of the 79 sites using dedicated STAs and was concerned about the ability of on-call STAs to maintain an adequate awareness of plant configuration and status. The staff also reported that some licensees assign the STA to concurrent roles such as fire brigade leader or communicator during an event.

NRR was assigned the lead to evaluate the effectiveness of licensee shift staffing practices, with the focus on staffing levels outside the control room, and a Task Action Plan was approved. This plan addresses the adequacy of shift staffing level requirements at nuclear power plants (NPPs) and includes assessment of the generic implications of assigning conflicting multiple responsibilities to the operating staff of NPPs for response to resource-intensive accidents. The plan considers whether there is a need to change or develop regulatory guidance regarding shift staffing requirements at NPPs. The plan included the issuance of an information notice to provide licensees the results and insights gained. This issue was identified in an NRR memorandum1601 to RES in February 1996.

Safety Significance

The minimum shift staffing (including non-licensed personnel) needed during an event challenges a backshift crew's ability to perform all necessary functions.

Possible Solution

Research on the subject was conducted and included: (1) a review and evaluation of experience and events for which staffing was a contributing factor; and (2) a detailed on-site survey of staffing practices at 7 facilities, including tabletop and walk-through exercises for specific accident sequences that could challenge staff resources. Upon completion of the research, the NRC was expected to review the results and issue an Information Notice regarding the findings. In April 1994, NRR broadened the scope of the staffing research and requested RES to include all licensee staff initially needed for an event.


The shift staffing study was published by BNL in two reports to the NRC and included the following findings:

(1) Licensees did not use a systematic process for establishing site-specific staffing levels, despite the availability of such methods.

(2) For all plants surveyed, the TS staffing requirements for SROs and ROs were equivalent to the minimum requirements of 10 CFR 50.54(m).

(3) Licensees frequently assign plant-specific tasks to be performed during an event that are not required by regulation.

(4) There was significant variation between plants in the number of licensed and non-licensed personnel that were administratively required.

(5) During scenario walk-throughs, similar-vendor licensees made significantly different decisions, resulting in very different control room activities and in-plant tasks.

(6) For all plants surveyed, the typical staffing levels were greater than the TS staffing requirements; however, these licensees were actively engaged in reducing operations and management costs. Such reductions could impact their future staffing levels.

Information Notice 95-481654 was issued to provide licensees with the results and the insights gained during the staff study. Although there had been, and continue to be, occasional events in which the adequacy of shift staffing and task allocation were called into question, the staff believed that, at the time the Notice1654 was issued, insufficient basis existed for a regulatory analysis which would support generic regulatory action in these areas. Accordingly, the staff will continue to monitor the adequacy of shift staffing and task allocation for events in which they are questioned, and will take plant-specific regulatory action as appropriate. Based on the actions described above, this issue was RESOLVED and no new requirements were established.1731


1079. NUREG-1275, "Operating Experience Feedback Report," U.S. Nuclear Regulatory Commission, (Vol. 1) July 1987, (Vol. 2) December 1987, (Vol. 3) November 1988, (Vol. 4) March 1989, (Vol. 5) March 1989, (Vol. 5, Addendum) August 1989, (Vol. 6) February 1991, (Vol. 7) September 1992, (Vol. 8) December 1992, (Vol. 9) March 1993.
1601. Memorandum for C. Serpan from A. Chaffee, "Nuclear Reactor Regulation (NRR) Input Into Research NUREG-0933 (WITS Item 9400213)," February 13, 1996. [9602260124]
1650. Letter to All Power Reactor Licensees and Applicants for Power Reactor Licenses, "Policy Statement on Engineering Expertise on Shift (Generic Letter 86-04)," U.S. Nuclear Regulatory Commission, February 13, 1986. [ML031150270]
1651. Information Notice 91-77, "Shift Staffing at Nuclear Power Plants," U.S. Nuclear Regulatory Commission, November 26, 1991. [ML031190410]
1652. Information Notice 93-44, "Operational Challenges During a Dual-Unit Transient," U.S. Nuclear Regulatory Commission, June 15, 1993. [ML031070483]
1653. Information Notice 93-81, "Implementation of Engineering Expertise on Shift," U.S. Nuclear Regulatory Commission, October 12, 1993. [ML031070314]
1654. Information Notice 95-48, "Results of Shift Staffing Study," U.S. Nuclear Regulatory Commission, October 10, 1995. [ML031060170]
1655.Letter to B. Boger (U.S. Nuclear Regulatory Commission) from R. Whitesel (Nuclear Management and Resources Council), December 29, 1992. [9301080124]
1656.SECY-93-184, "Shift Staffing at Nuclear Power Plants," U.S. Nuclear Regulatory Commission, June 29, 1993. [9307080273]
1657.SECY-93-193, "Policy on Shift Technical Advisor Position at Nuclear Power Plants," U.S. Nuclear Regulatory Commission, July 13, 1993. [9307200065]
1731.Memorandum for W. Russell from D. Morrison, "Prioritization of the NRR Action Plans Submitted to RES on February 13, 1996," June 24, 1996. [9606260260]