Information Notice No. 91-36: Nuclear Plant Staff Working Hours
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
June 10, 1991
Information Notice No. 91-36: NUCLEAR PLANT STAFF WORKING HOURS
All holders of operating licenses or construction permits for nuclear power
This information notice is intended to alert addressees of potential
problems resulting from inadequate controls to prevent excessive plant staff
working hours. It is expected that recipients will review the information
for applicability to their facilities and consider actions, as appropriate,
to avoid similar problems. However, suggestions contained in this
information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances:
On October 4, 1990, Braidwood Station, Unit 1 lost approximately 620 gallons
of water from the reactor coolant system (RCS) while the reactor was in cold
shutdown. The Braidwood technical staff was conducting two residual heat
removal (RHR) system surveillances concurrently. Before fully closing an
RHR system vent valve in accordance with one surveillance procedure, the
staff opened an RHR system isolation valve as specified in the other
surveillance procedure. RCS coolant at 360 psig and 180xF exited the vent
valve, ruptured a tygon tube line, and sprayed two engineers and the
equipment attendant who were in the vicinity of the vent valve. An NRC
augmented inspection team (AIT) conducted an onsite review of this event.
The AIT reported that the fatigue from excessive use of overtime by the
technical staff was a main contributor to this event.
In an August 1990 NRC Diagnostic Evaluation Team (DET) report, the NRC staff
documented high amounts of overtime for personnel at the Zion Station.
Individuals in the operations department regularly exceeded the working hour
guidelines contained in Generic Letter 82-12, "Nuclear Power Plant Staff
Working Hours," and in Zion's administrative procedures. In November 1990,
the NRC performed an audit and identified numerous additional deviations
from Zion's administrative procedure for approving, tracking, and reporting
overtime. These deviations occurred in 1989 and 1990.
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Although the audit team could not connect a specific operating event or
human error to fatigue caused by excessive overtime, the amount of overtime
worked caused the NRC concern regarding the adequacy of the licensee's
staffing. Generic Letter 82-12 states that controls established should
ensure that, to the extent practical, personnel are not assigned to shift
duties while in a fatigued condition that could significantly reduce their
mental alertness or their decisionmaking ability. The licensee should
employ enough plant operating personnel to maintain adequate shift coverage
without routine heavy use of overtime. The objective is to have operating
personnel work a nominal 40-hour week while the unit is operating.
During the 1989 refueling outage at the San Onofre Nuclear Generating
Station, Unit 2, the Southern California Edison Company (the licensee) had
an outage shift schedule policy which required San Onofre Unit 3 operating
personnel to work the same shift schedule as Unit 2. San Onofre Unit 3 was
operating in Mode 1 during this time. Similarly, from March through May
1989 at the Alabama Power Company's Joseph M. Farley Nuclear Plant, the
licensee established an outage shift schedule for both Unit 1 and Unit 2
even though only one of the two units was in an outage. In these cases,
plant personnel for an operating unit were placed on a site outage schedule,
a practice that is inconsistent with the intent of the TMI Action Plan,
NUREG-0737, Item I.A.1.3, and Generic Letter 82-12 (letter from S. A. Varga,
NRC, to W. G. Hairston III, Alabama Power Company, dated May 24, 1991,
"Operator Work Schedules at the Joseph M. Farley Nuclear Plant, Units 1 and
On November 5, 1990, at the Sequoyah Nuclear Plant, an NRC inspection team
reviewed the records of hours worked for the Operations section for the week
of October 8, 1990. The inspection team found 23 instances of inadequate
documentation for exceeding overtime limits and 5 instances of overtime
authorization prepared after the fact.
In January 1991 at the Callaway Plant, Unit 1, NRC inspectors reviewed "time
on site" for selected contract personnel for the previous refueling outage.
Two of the contract personnel worked on safety-related systems and exceeded
overtime limits without receiving individual authorizations. However, the
licensee had issued a single authorization to cover all of that contractor's
personnel engaged in safety-related work. To be consistent with Generic
Letter 83-14, "Definition of 'Key Maintenance Personnel' (Clarification of
Generic Letter 82-12)," Callaway has decided to expand the procedural
control of staff working hours to include engineers when they are
"directing" safety-related work.
Discussion of Safety Significance:
The safety of nuclear power plant operations and the assurance of general
public health and safety depend on personnel performing their jobs at
adequate levels. Research on extended working hours indicates that the
performance of individuals will degrade without adequate rest after long
periods of work. Fatigue can degrade an operator's ability to rapidly
process complex information such as that presented by off normal plant
conditions. In addition, fatigue may jeopardize the ability to respond in a
timely fashion. Furthermore, performance errors are more likely to occur as
a result of lapses in
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short-term memory. Because individuals performing safety-related duties may
be required to respond quickly to a plant emergency, it is important for
plant management to carefully exercise control over overtime practices in
order to ensure that plant personnel perform adequately.
Related Generic Communications:
1. NRC Generic Letter 82-12, "Nuclear Power Plant Staff Working Hours,"
June 15, 1982.
2. NRC Generic Letter 82-16, "NUREG-0737 Technical Specifications,"
September 20, 1982.
3. NRC Generic Letter 83-02, "NUREG-0737 Technical Specifications,"
January 10, 1983.
4. NRC Generic Letter 83-14, "Definition of 'Key Maintenance Personnel'
(Clarification of Generic Letter 82-12)," March 7, 1983.
5. NUREG-0737, "TMI Action Plan," November 1980.
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate NRR project
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: David Desaulniers, NRR
Jesse Arildsen, NRR
Attachment: List of Recently Issued NRC Information Notices
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