NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
April 14, 1997
|NRC INFORMATION NOTICE 97-18:||PROBLEMS IDENTIFIED DURING MAINTENANCE RULE BASELINE INSPECTIONS|
All holders of operating licenses, construction permits, and decommissioning-stage licenses for nuclear power reactors.
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert addressees to the problems identified during the 10 CFR 50.65 (maintenance rule) baseline inspections performed from July 1996 through February 1997. It is expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. In addition, recipients are reminded that they are required to take industry-wide operating experience (including NRC Information Notices) into consideration, where practical, when setting goals and performing periodic evaluations under the maintenance rule. Since suggestions contained in this information notice are not NRC requirements, no specific action (other than those required by the maintenance rule) or written response is required.
The NRC published the maintenance rule on July 10, 1991, as Section 50.65, "Requirements for monitoring the effectiveness of maintenance at nuclear power plants," of 10 CFR Part 50. The rule became effective, after a five year implementation period, on July 10, 1996. The rule requires licensees to monitor the effectiveness of maintenance activities for safety-significant plant equipment in order to minimize the likelihood of failures and other events caused by lack of effective maintenance.
The nuclear industry developed a guideline for implementing the maintenance rule, formerly Nuclear Management and Resources Council now known as Nuclear Energy Institute (NUMARC) 93-01, "Industry Guidance for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants (May 1993)." Revision 2 to NUMARC 93-01 was issued in April 1996 to address lessons learned from pilot inspections performed at nine nuclear power plants. In March 1997, the NRC issued Revision 2 to Regulatory Guide (RG) 1.160 , "Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," which endorsed, with clarifications, NUMARC 93-01, Revision 2, as providing methods acceptable for complying with the provisions of the rule.
Description of Circumstances
To ensure the effective implementation of the maintenance rule, the NRC staff is in the process of performing a baseline inspection at each licensed facility. These inspections began in July 1996 and are expected to be completed in July 1998. Inspection findings from the first 20 baseline inspections are discussed below; a list of the inspection reports that have been issued to date is provided in Attachment 1.
|1.||Failure To Include Emergency Lighting and Communications Systems
in the Scope of Rule
|In 10 CFR 50.65(b) the regulations require that the scope of the maintenance rule include nonsafety-related
structures, systems, and components (SSCs) that are relied upon to mitigate accidents or transients or that are used in
plant emergency operating procedures. On the basis of interviews of licensed plant operators at many sites, the NRC
staff determined that operators typically rely on various types of communications systems (e.g., radios, telephones,
public announcement equipment) when performing their duties during an accident or transient. In addition, operators
rely on the emergency lighting system(s) to provide lighting to perform their accident or transient mitigation duties
on a loss of normal plant lighting. Despite this reliance, a number of licensees had excluded emergency lighting and
communications systems from the scope of the rule.
The NRC staff has issued notices of violation to licensees for failing to include communications system(s)
equipment and emergency lighting system(s) within the scope of the maintenance rule without adequate justification
to show why the system(s) are not relied upon during accident or transient conditions.
|2.||Failure To Establish Appropriate Reliability and Availability Goals and Performance Criteria|
|Section 50.65(a)(1) requires that goals be established commensurate
with safety. NUMARC
provides methods acceptable to the NRC for meeting 10
CFR 50.65 (a)(1) and (a)(2) requirements. Using the NUMARC
guidance, performance criteria that are used to demonstrate effective preventive
maintenance for high safety significant SSCs should be established to ensure
that reliability and availability assumptions used in plant-specific safety
analyses are maintained or adjusted. Several licensees failed to demonstrate
that goals and performance criteria m requirements were established commensurate
with safety. For example, several licensees established a single performance
criterion for reliability (e.g., number of maintenance preventable functional
failures [#MPFFs]/2 years) without an adequate technical basis. In some
cases, when compared to the number of demands, the number of MPFFs allowed
would be indicative of much lower reliability than the licensee assumed
in its risk analysis. More specifically, licensees failed to demonstrate
that the criterion preserved the assumptions defined by plant-specific probabilistic
risk assessments, individual plant examinations, or other risk determining
analyses. Also, several licensees failed to establish an availability performance
criterion for certain high safety significant SSCs.
Section 50.65(a)(3) requires balancing the reliability achieved through preventative maintenance against the
objective of minimizing unavailability. When establishing goals and performance criteria under 10 CFR 50.65 (a)(1)
and (a)(2) of the rule, some licensees could not adequately perform that balancing because the reliability
performance criteria for some SSCs were inadequate or SSC availability performance criteria were not established.
|3.||Failure To Adequately Assess Risk Prior to Taking SSCs Out of Service for Monitoring or Preventive Maintenance|
|Section 50.65(a)(3) states, in part, that in performing monitoring and preventive maintenance activities, an
assessment of the total plant equipment that is out of service should be taken into account to determine the overall
effect on performance of safety functions. Several licensees' processes and programs were found to be weak in
assessing the safety impact of removing equipment from service for maintenance or monitoring.|
|a.||At one facility several examples were identified where the licensee underestimated the risk associated with
plant configurations established for performing on-line preventive maintenance. For this facility, one unit was
operating for extended periods with a power operated relief valve block valve shut and a pressurizer spray
valve out of service. The licensee did not recognize that this configuration contributed to plant risk. As a
result, on several occasions, the increase in core damage frequency associated with taking additional plant
equipment out of service for maintenance was significantly underestimated.|
|b.||At other facilities, the licensees' processes for assessing safety impact were weak. Risk matrices and other risk
assessment tools used by some licensee's for assessing the acceptability of taking combinations of equipment
out of service were too limited in scope and in some instances, failed to include risk significant systems.
Procedures for using these risk assessment tools did not always provide sufficient guidance on their
limitations. In addition, personnel responsible for making these assessments were not always knowledgeable
of the limitations of these tools.|
|4.||Failure to Include Decommissioning Stage Reactor SSCs Within the Scope of the Maintenance Rule |
|As stated in Section 50.65(a)(1), the maintenance rule applies to "Each holder of a license to operate a nuclear power
plant under Sections 50.21(b) or 50.22." During the Dresden Independent Safety Inspection 50-237/96-201;
50-249/96-201 (Accession Number 9612270052) the NRC inspectors identified that the licensee had incorrectly
excluded from the scope of the rule certain Unit 1 SSCs that are required to ensure the spent fuel is maintained in a
safe condition. Although the licensee had established appropriate surveillance activities for these SSCs, they had not
established goals or performance criteria as required by the rule. They believed that Unit 1 was no longer considered
an operating plant because it had been defueled and therefore did not come under the scope of the rule. However, the
NRC inspectors confirmed that even though the Unit 1 license had been amended for possession only, it remained an
operating license under Section 104 of the Atomic Energy Act, as described in 10 CFR 50.21(b) and, therefore;
should have been included within the scope of the maintenance rule. The failure to include certain Unit 1 SSCs
within the scope of the rule was identified as a deficiency.|
|The maintenance rule was amended effective on August 28, 1996 to clarify the requirements for nuclear power plants that had decided to terminate their license. Section 50.65(a)(1) now states that for a nuclear power plant for which the licensee has submitted the certifications specified in Section 50.82(a)(1), this section shall apply only to the extent that the licensee shall monitor the performance or condition of all SSCs associated with the storage, control, and maintenance of spent fuel in a safe condition, in a manner sufficient to provide reasonable assurance that such SSCs are capable of performing their intended functions. These requirements include setting goals or performance criteria for any SSCs required to maintain the spent fuel in a safe condition; monitoring against those goals or performance criteria, and taking appropriate corrective action when those goals are not met.|
In order to ensure industry-wide understanding, the staff has clarified these issues and others in Revision 2 to RG 1.160. In addition, as part of its efforts to maintain effective communication with the industry and the public regarding the maintenance rule, the NRC staff has developed a "Home Page" for the World Wide Web. The intent of the home page is to provide a comprehensive, up to date, resource of maintenance rule-related regulatory documents, guidance documents, inspection procedures, and inspection reports in a searchable format. The NRC staff will make the Home Page publicly accessible after prototype testing is complete.
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 Office of Nuclear Reactor Regulation (NRR) project manager.
|signed by M.M. Slosson
Thomas T. Martin, Director
|Technical contacts:||Donald R. Taylor, NRR |
Charles D. Petrone, NRR
|Attachments:||1. List of Maintenance Baseline Inspection Reports|
(NUDOCS Accession Number 9704110050)
April 14, 1997
LIST OF MAINTENANCE BASELINE INSPECTION REPORTS
|PLANT||REPORT NO.||DATE ISSUED||ACCESSION NO.|
|Palo Verde Units 1, 2 & 3||50-528/96-09
|Peach Bottom Units 2 & 3||50-277/96-07
|St. Lucie Units 1 & 2||50-335/96-13
|D.C. Cook Units 1 & 2||50-315/96-09
|Hatch Units 1 & 2||50-321/96-12
|Sequoyah 1 & 2||50-327/96-12
|Prairie Island Units 1 & 2||50-282/96-12
|Nine Mile Point Unit 1||50-220/96-12||01/15/97||9701240126|
|Perry Unit 1||50-440/96-14||01/29/97||9702050111|
|Washington Nuclear Project 2||50-397/96-18||01/29/97||9702030185|
|Indian Point 3||50-286/96-80||02/14/97||9702210210|
|Surry Units 1 & 2||50-280/97-01
|Davis-Besse Unit 1||50-346/97-02||03/06/97||9703110189|
|Catawba Units 1 & 2||50-413/97-01
|03/20/97||* not available|
|Waterford Unit 3||50-382/97-01||03/21/97||* not available|
* As of the date of this information notice, the inspection report had not been entered into the NRC NUDOCS system.