￼Dominion Virginia Power’s Surry plant could become the first US nuclear plant to be allowed to operate for up to 80 years. Thecla Fabian reports.
Dominion informed the US Nuclear Regulatory Commission (NRC) on 6th November 2015 that it would apply for a second 20-year life extension for its Surry units. David Christian, chief executive of Dominion Generation, announced the plan later the same day at President Obama’s White House symposium on the future of nuclear energy. Under the 1954 Nuclear Energy Act, as amended, NRC can issue licences to commercial reactors to operate for up to 40 years. In December 1991, NRC issued regulations that allowed it to renew these licences in 20-year increments, with no limit on the number of times NRC can renew a licence.
NRC bases each licence renewal decision on an assessment of whether the reactor can continue to meet safety and environmental requirements throughout the 20-year period of extended operation.
As of December 2015, NRC had issued 20- year life extensions to 81 reactors, of which two ceased operations before the end of the 20-year period. Of the remainder, 37 have operated for more than 40 years. But until Surry, no US nuclear operator had announced that it would seek a second licence extension that would allow the reactor to operate for 60-80 years.
The two Surry units, both three-loop Westinghouse pressurised water reactors (PWRs), provide 1676MWe, or about 20% of the electricity for the state of Virginia. Unit 1 was licensed in 1972 and Unit 2 in 1973. Both units received their first 20-year licence extensions on 20th March 2003. A second licence extension would allow them to operate until 2052 and 2053, respectively.
Dominion, which is one of the largest US power producers with around 24GWe of capacity, is also considering licence extension for its two-unit North Anna plant in Louisa County, Virginia. The North Anna units have received their first licence extensions, and are licensed to operate until 2038 and 2040, respectively. Since 2001, Dominion has been working towards building a third reactor at North Anna. Together, Surry and North Anna provide 40% of Virginia’s electricity.
Launching a $2.5bn investment
Dominion’s letter of intent marks the beginning of a year-long process of testing and inspections that Dominion expects will cost $1.5-2.5bn. "Dominion is reviewing technical aspects of the second licence renewal, and has not found any showstoppers," Christian said. One of the things Dominion seeks to determine is whether any major equipment replacements or retrofits will be required for the application, the company’s press officer Richard Zuercher told NEI.
Dominion is managing the second licence extension application work in-house, Zuercher said. It expects to file its technical application, which will run to several thousand pages, with NRC in early 2019.
Dominion’s board of directors must approve the final decision to submit the technical application, but the letter of intent allows NRC to plan for staffing to support the licence renewal. The final board vote could come as early as this year, Zuercher said.
Christian called Dominion’s decision good news for its customers and Virginia. "Our customers will benefit by continuing to receive safe, reliable and low-cost electricity from the station through the middle of the century," he said. The licence extension also supports almost 1.000 high-paying jobs at the plant and will have economic and tax benefits for the state, he added.
Virginia’s two nuclear plants provide most of the state’s carbon-free power generation, and could be crucial to Virginia’s ability to meet its Clean Power Plan goals (new federal rules that require states to reduce the amount of carbon dioxide generated by electricity generation).
NRC, under its Subsequent Licence Renewal (SLR) programme, is preparing guidance documents on extending the licences of power plants beyond 60 years. The new documents — Generic Ageing Lessons Learned for Subsequent Licence Renewal (GALL-SLR) and Standard Review Plan for Subsequent Licence Renewal Applications for Nuclear Power Plants (SRP-SLR) — describe ageing management programmes that NRC considers acceptable. They are based on similar documents covering initial licence renewals for operations up to 60 years.
The final documents will describe the methods and techniques NRC considers acceptable in reviewing applications, and will provide useful information for licensees as they prepare their applications. NRC will hold public meetings on the draft guidance documents in January and February 2016, and will accept public comments until 29th February 2016. NRC will meet US nuclear trade association, the Nuclear Energy Institute, on 11th March. The Institute published a roadmap to SLR issues in May 2015.
NRC expects to publish the final GALL-SLR and SRP-SLR reports in July 2017, after its Advisory Committee on Reactor Safety (ACRS) reviews the proposed final guidance documents in March 2017. NRC’s final revisions will be necessary for Dominion’s technical application, but NRC’s schedule will not hinder preliminary work, Zuercher said.
The GALL-SLR report will include guidance for SLR applicants, the NRC staff’s generic evaluation of plant ageing management programmes and the technical basis for determining the adequacy of ageing management programmes.
The SRP-SLR report will provide guidance to NRC staff in reviewing licence applications. It aims to ensure the quality and uniformity of NRC staff reviews and to present a well-defined base from which to evaluate applicants’ programmes and activities for extended operations..
The existing licence renewal review process follows the guidance established in NRC’s NUREG-1800, ‘Standard Review Plan for Review of Licence Renewal Applications for Nuclear Power Plants’ (SRP-LR). SRP-LR references NUREG-1801, ‘Generic Ageing Lessons Learned (GALL) Report’, which documents the NRC staff’s generic basis for determining the adequacy of existing ageing management programmes (AMPs), identifies which need to be augmented for licence renewal, and where new programmes are required, along with information related to the results of ageing management reviews and time-limited ageing analyses.
NRC has already revised the GALL Report and SRP-LR twice, based on the experience the NRC staff gained in reviewing licence renewal applications.
Open technical issues
In January 2014, the NRC staff submitted its report to NRC’s five-member governing Commission, SECY-14-0016, ‘Ongoing Staff Activities to Assess Regulatory Considerations for Power Reactor Subsequent Licence Renewal’.
The Commissioners responded in August 2014 with a memorandum that directed the staff to keep the Commissioners informed on resolving technical issues related to SLR, including: pressure vessel neutron embrittlement at high fluence; irradiation- assisted stress corrosion cracking of reactor internals and primary system components; concrete and containment degradation; and electrical cable qualification and condition assessment.
It also required staff to:
- Continue to update the licence renewal guidance to provide more clarity on implementation of the SLR regulatory framework.
- Report on the staff’s progress in improving inspection related to ageing management, as described in the reactor oversight enhancement project, and how the inspection procedure is updated.
- Report on the staff’s readiness to accept an application and any need for regulatory process changes, rule making or research.
- Communications with industry on satisfactory resolution of any highlighted issues before the NRC begins to review of any application.
Industry prepares early
Dominion is engaged with licence renewal programmes at Nuclear Energy Institute, the Electric Power Research Institute (EPRI) and the Light Water Reactor Sustainability (LWRS) Programme at the Department of Energy’s Idaho National Laboratory, and is sharing information with these programmes, Zuercher said: "It is important that this process is coordinated with the industry to prevent any unintended consequences to others by us going it alone."
The decision to pursue licence renewal is an economic one affected by the costs of continued operations, major component replacements, operations and maintenance costs, and local electricity markets, the Nuclear Energy Institute said in its May 2015 Second Licence Renewal Roadmap. It estimated the cost and time required for application and review of a SLR would be similar to a first licence renewal, because the regulatory process would be the same and lessons learned from the first round of licence renewals may make the preparation and review process more efficient.
A licence renewal application cannot be submitted more than 20 years before the expiration of a plant’s current operating licence, and only after the plant has entered a period of extended operation.
It is essential an applicant demonstrates that plant structures, systems, and components can be managed so that the current licensing basis can be maintained throughout the subsequent period. The current licensing basis is the set of NRC requirements applicable to a specific plant and a licensee’s written commitments for ensuring compliance with NRC requirements and the design basis. This includes modifications and additions to such commitments over the licence period. It also includes the continuously updated final safety analysis report.
Nuclear Energy Institute performed a broad-scope assessment to identify the steps needed to proceed to plant operations beyond 60 years. The assessment covered research and development, operations, industry support and the licence renewal programmes and processes already in place. The roadmap documented the results of the assessments and provided a plan for achieving NRC approval of the first applications.
Ageing management programmes are key to the licence renewal process, Nuclear Energy Institute notes. Industry and federal government laboratories are conducting research for safe, long-term plant operation. The US nuclear industry has developed a comprehensive programme to manage and coordinate materials research, known as the "Guideline for the Management of Materials Issues" (NEI 03-08. All US nuclear operators have adopted the programme..
EPRI co-ordinates research programmes under its materials management programme. These include: BWR vessel and internals; PWR materials and reliability; steam generator management; primary system corrosion research; nondestructive examination; water chemistry control; and the PWR Owners Group materials management activities.
The NEI also has an active task force that meets quarterly to manage licence renewal issues and guide progress in preparing for applications. The task force meets publicly with NRC’s staff to share information. Four subgroups support the task force, on implementation, civil/structural, electrical and mechanical issues.
Research base in place
Two organisations are conducting advanced materials R&D to support licence renewal: EPRI’s Long-Term Operations (LTO) programme and DOE’s Light Water Reactor Sustainability (LWRS) programme at Idaho National Laboratory.
EPRI launched its international LTO programme in 2010 develop the technical basis for reactor operations beyond 60 years. The programme addresses the technical basis for extended operation of systems, structures and components that could limit plant operations, including reactor pressure vessels and other large structures. The programme also seeks to modernise instrumentation and control systems; develop enhanced safety and risk analysis methods; and develop enabling technologies such as lifecycle management and plant demonstration projects.
DOE’s LWRS programme works with industry and NRC to conduct long-term research to inform major component refurbishment and replacement strategies, performance enhancement, plant licence renewals and ageing-related regulatory oversight.
LWRS seeks to develop the scientific basis for understanding, predicting, and measuring changes in materials and structures, systems and components as they age in environments associated with continued long-term operation of existing plants. It seeks to apply this fundamental knowledge to develop and demonstrate methods and technologies that support long-term operation of existing plants.
According to the NEI roadmap there remains a need for industry to:
- Revise the Institute of Nuclear Power Operators (INPO) operating experience process to support ageing management data, as well as develop an industry approach to review and share age-related degradation operating experience.
- Provide industry input to NRC’s standard review plan and Generic Ageing Lessons Learned revision process. NEI has formed an expert panel consisting of the chairs of the electrical, civil/structural, mechanical and implementation working groups and other senior industry experts, which will meet NRC.
- Develop a PWR reactor vessel surveillance programme to provide data on the embrittlement of operating plants through 80 years of service. EPRI has two programmes to address the issue: the Coordinated PWR Reactor Vessel Surveillance Programme (CRVSP) will have 13 PWRs defer the withdrawal of capsules to test them at higher fluences; and the PWR Supplemental Surveillance Programme (PSSP) will design, fabricate, irradiate and test one or two supplemental capsules containing previously irradiated PWR material. CRVSP will operate from 2015 to 2029, and PSSP from 2015 to 2024.
- Extend the BWR integrated surveillance programme from 60 to 80 years to ensure management and monitoring of reactor pressure vessel embrittlement through the period.
- Revise NEI95-10 guidance (which provides an NRC-endorsed acceptable approach for implementing the requirements of 10 CFR Part 54), based on lessons learned, operating experience, and the outcome of NRC’s revision of the GALL report and SRP. Dominion will have the revised guidelines available to assist in drafting its licence application.
- Evaluate EPRI ageing management tools. These technical tools provide materials ageing information and guidance for plant staff in preparing ageing management plans. They cover electrical, mechanical, civil and structural components.
- Prepare a lead plant application. The lead plant operator (Dominion) will take two or three years to prepare the application and submit it. Surry will work closely with NRC, EPRI and the Nuclear Energy Institute SLR working group to resolve issues as they arise and capture lessons learned.
- The first set of renewed licence terms will end in 2029. NEI said that submitting an SLR application by 2018/19 will provide enough lead time for NRC to review and approve the application in advance of the operating licence expiration date for the first plants that received initial licence extensions. The first SLR application will also be an example for other operators to follow.