ML15286A258
| ML15286A258 | |
| Person / Time | |
|---|---|
| Site: | Kewaunee  |
| Issue date: | 01/20/2016 |
| From: | John Tappert Division of Decommissioning, Uranium Recovery and Waste Programs |
| To: | Heacock D Dominion Energy Kewaunee, Dominion Nuclear |
| Koenick S, DORL/LPLIV-2, 415-6631 | |
| Shared Package | |
| ML15286A229 | List: |
| References | |
| 2.206, OEDO-15-00251 | |
| Download: ML15286A258 (21) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 20, 2016 Mr. David A. Heacock President and Chief Nuclear Officer Dominion Nuclear Dominion Energy Kewaunee, Inc.
Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
Dear Mr. Heacock:
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the petition submitted by Mr. Michael Mulligan dated March 25, 2014 [sic], sent by e-mail dated March 26, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15090A487), with respect to the Vermont Yankee Nuclear Power Station and the Kewaunee Power Station. Mr. Mulligan supplemented his petition by e-mails dated July 7 and September 9, 2015 (ADAMS Accession Nos. ML15198A091 and ML15286A003, respectively).
Enclosed is the NRC staff's proposed director's decision under Title 10 of the Code of Federal Regulations 2.206, "Requests for Action under this Subpart."
I request that you provide comments to me on any portions of the decision that you believe involve errors or any issues in the petition that have not been fully addressed. The NRC staff is making a similar request of the petitioner. The NRC staff will then review any comments that you and the petitioner provide and consider them in the final version of the director's decision, with no further opportunity to comment.
Please provide your comments within 14 calendar days from the date of this letter.
Sincerely,
~
/l 7 J hn R. Tap e , Director ision of Decommissioning, Uranium Recovery and Waste Programs Office of Nuclear Material Safety and Safeguards Docket No. 50-305
Enclosure:
Proposed Director's Decision cc: Listserv
ENCLOSURE PROPOSED DIRECTOR'S DECISION ML15286A272
[7590-01-P]
Proposed DD-XX-XX UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION William M. Dean, Director In the Matter of Docket Nos. 50-271 and 50-305 ENTERGY NUCLEAR OPERATIONS, INC.
DOMINION ENERGY KEWAUNEE, INC. License Nos. DPR-28 and DPR-43 Vermont Yankee Nuclear Power Station and Kewaunee Power Station PROPOSED DIRECTOR'S DECISION UNDER 10 CFR 2.206 I. Introduction By letter dated March 25, 2014 [sic] (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15090A487), Michael Mulligan (the petitioner) filed a petition under Title 10 of the Code of Federal Regulations (10 CFR) 2.206, "Requests for Action under this Subpart," related to the Vermont Yankee Nuclear Power Station (VY) and the Kewaunee Power Station (KPS).
The petition was supplemented by e-mails dated July 7, 2015 (ADAMS Accession No. ML15198A091), and September 9, 2015 (ADAMS Accession No. ML15286A003).
Actions Requested for the March 25, 2014 [sic]. Petition The petitioner requested that the U.S. Nuclear Regulatory Commission (NRC or the Commission) take a number of actions with regard to VY and KPS, which have been permanently shut down and are currently undergoing decommissioning, to include:
- Conduct exigent and immediate full-scale ultrasonic inspections on the VY and the KPS reactor pressure vessels (RPVs), with similar or better technology, as conducted on the RPVs at Dael 3 and Tihange 2, which revealed thousands of cracks.
- Take large borehole samples out of both the VY and KPS RPVs and transport them to a respected metallurgic laboratory for comprehensive offsite testing.
- Issue an immediate NRC report and hold a public meeting on any identified vulnerabilities.
- Ultrasonically test all RPVs in U.S. plants within 6 months if distressed and unsafe results are discovered at VY or KPS.
As the basis for this request, the petitioner states that the requested actions should be taken to determine whether foreign operating experience (OpE)-specifically several thousand cracks that have been discovered during testing on the Dael 3 and Tihange 2 RPVs-could have implications on U.S. operating reactors. The petitioner also requested several related actions of the NRC, such as, collaboration with the Belgian regulator, and posed several questions related to water chemistry and the discovered cracks.
The petitioner met with the petition review board on May 19, 2015, to clarify the bases for the petition. The transcript of this meeting was treated as a supplement to the petition (ADAMS Accession No. ML15181A127) and is available for inspection at the NRC's Public Document Room (PDR), located at One White Flint North (01 F21 ), 11555 Rockville Pike (first floor), Rockville, Maryland 20852. Publicly available documents created or received at the
NRC are accessible electronically through ADAMS in the NRC Library at http://www.nrc.gov/reading-rm/adams.html. Persons who do not have access to ADAMS or who encounter problems in accessing the documents in ADAMS should contact the NRC's PDR reference staff by telephone at 1-800-397-4209, or 301-415-4737, or by e-mail to pdr.resource@nrc.gov.
The NRC's acknowledgement letter to the petitioner for the March 25, 2014 [sic], petition dated August 20, 2015 (ADAMS Accession No. ML15181A099), informed the petitioner that his request for conducting exigent and immediate full-scale ultrasonic inspections on the VY and the KPS RPVs was denied and that the remaining issues in the petition were being referred to the Office of Nuclear Reactor Regulation (NRR) for appropriate action. The NRC denied the petitioner's request to conduct immediate ultrasonic inspections at VY and KPS for the following reasons. The identified facilities have ceased operations and there is no safety concern at those facilities that justifies enforcement-related action (i.e., to modify, suspend, or revoke the license) in order for the NRC to have reasonable assurance of the adequate protection of public health and safety. Furthermore, with respect to the operating fleet, the NRC issued Information Notice (IN) 2013-19, "Quasi-Laminar Indications in Reactor Pressure Vessel Forgings," dated September 22, 2013 (ADAMS Accession No. ML13242A263). The purpose of IN 2013-19 was to inform industry of the quasi-laminar indications that were identified in 2012 at two European commercial nuclear power plants during the ultrasonic inspections of those RPV forgings.
II. Discussion Disposition of the March 25, 2014 [sic], Petition Under the 10 CFR 2.206(b) petition review process, the Director of the NRC office with responsibility for the subject matter shall either institute the requested proceeding or shall advise the person who made the request in writing that no proceeding will be instituted, in whole
or in part, with respect to the request, and the reason for the decision. Accordingly, the decision of the NRR Director is provided below.
It is the policy of the NRC to have an effectively coordinated program to promptly and systematically review domestic and applicable international OpE information gained from the nuclear power industry, research and test reactors, and new reactor construction. The program supplies the means for assessing the significance of OpE information, offering timely and effective communication to stakeholders, and applying the lessons learned to regulatory decisions and programs affecting nuclear reactors. This program is referred to as the Reactor OpE Program, as described in the NRC Management Directive (MD) 8.7, "Reactor Operating Experience Program." Specific implementation of the Reactor OpE Program is addressed in NRR Office Instruction (01) LIC-401, "NRR-NRO [Office of New Reactors] Reactor Operating Experience Program."
One of the sources of OpE is the International Atomic Energy Agency (IAEA)/Nuclear Energy Agency (NEA) International Reporting System for Operating Experience (IRS). The Deel experience was reported to the IRS. Subsequently, the report was updated to include the Tihange experience. In accordance with the process described in 01 LIC-401, the NRC OpE program staff ensured that the appropriate technical experts within the NRC were aware of the issue and performing evaluations for relevance to the U.S. industry. In addition, the NRC has strong collaboration with the international community and was separately in contact with the Belgian regulatory authority, the Federal Agency for Nuclear Control (FANC), to discuss this issue.
The NRC staff has been following the issue and has taken numerous actions. Most recently, the NRC staff used its risk-informed decision-making process contained in NRR 01 LIC-504, "Integrated Risk-Informed Decision-Making Process for Emergent Issues," to
evaluate this issue. The evaluation (ADAMS Accession No. ML15282A218) is summarized below.
Description of the Issue In July 2012, ultrasonic inspections of RPV ring forgings at the Doel 3 and Tihange 2 nuclear power plants in Belgium revealed thousands of indications. 1 After extensive investigation the Belgian licensee, Electrabel, concluded the indications consisted of hydrogen flakes that originated during fabrication. Hydrogen flakes are planar discontinuities produced during fabrication in steels that have elevated hydrogen content before forging. In the Doel 3 and Tihange 2 inspections, the identified flakes were approximately circular disc-shaped cracks, were on average 10 millimeters in diameter, and were oriented approximately parallel to the vessel wall. Electrabel performed deterministic flaw evaluation and probabilistic fracture mechanics (PFM) analyses and concluded: (1) the indications would have been acceptable according to the requirements of the construction codes in effect when the vessels were fabricated (as well as the codes in effect today), and (2) the indications did not pose a challenge to RPV structural integrity. The licensee started a program of materials research and operational inspections to further validate the structural integrity determination of the RPV forgings. FANC initially approved restart of the two reactors in May of 2013. Information related to this issue is publicly available on the FANC Web site:
http://www. fanc. fgov. be/nl/page/dossier-pressure-vessel-doel-3-tihange-2/1488 .aspx?LG=2.
In an ultrasonic examination, indications are features inside the inspection volume that reflect sound above a threshold that is established as part of the examination procedure. Generally, the inspection procedure will define thresholds of reflectivity that examiners use to categorize indications, with more reflective indications being categorized as more significant. Indications that reflect enough sound to be detected are termed "detectable." Detectable indications that reflect sound above a certain threshold such that the procedure requires them to be recorded are termed "recordable." Generally, recordable indications must be evaluated.
Applicable codes and standards referenced in the procedure or design specification establish criteria to determine whether recorded indications are "acceptable" or "rejectable." Rejectable indications are termed "flaws," or "defects" that, per ASME [American Society of Mechanical Engineers] practice, must be repaired.
Rejectable indications are "reportable" to the regulatory authority.
While the Doel 3 and Tihange 2 reactors were shut down for outages in 2014, the ring forgings were reinspected for quasi-laminar flaws. During the 2012-2013 campaign, the licensee quantified the number of recordable indications, but recognized that many indications were detected that returned signal responses below the procedurally established recording threshold. For the 2014 examination, the licensee adjusted the ultrasonic inspection procedure by changing recording thresholds and increasing sensor gain. The objective was to record essentially all detectable indications. Newly recorded indications included cases where multiple indications spaced closely together, that were previously recorded as one large indication, could now be distinguished as several discrete indications. Most of these newly recorded indications were detected but not recorded during the previous exam, because they were too small to meet the previously used recording criteria. After comparing the indications from the 2012 and the 2014 inspections, the Belgian licensee concluded that the actual number and size of detected indications did not change over the period.
In March 2014, results from the ongoing Electrabel materials investigation became available to the FANG. The results from one of the materials tested showed a greater amount of embrittlement than assumed in its safety case. Consequently, the licensee elected to place both Doel 3 and Tihange 2 into an early maintenance outage to conduct further investigation.
The material with the higher-than-expected embrittlement was a modern steel made to a specification similar to that used for the Doel 3 and Tihange 2 RPVs. The component was a steam generator shell that had been rejected because of hydrogen flaking, and was, therefore, included as part of the Electrabel investigation. After the March 2014 results, Electrabel performed several materials irradiation experiments that included the steam generator material as well as other materials thought to be more representative of RPV steels in Doel 3 and Tihange 2.
On November 17, 2015, FANC reported that Electrabel demonstrated that the unexpected test results of March 2014 were probably due to the specific material properties of the sample. Tests on another material specimen with hydrogen flakes and on the material of the reactor vessels themselves have shown that prolonged irradiation has no abnormal effect on the mechanical properties of the reactor vessels of Deel 3 and Tihange 2. FANC concluded that the structural integrity of the reactor vessels of Deel 3 and Tihange 2 lies within the required safety standards and the presence of hydrogen flakes does not adversely affect the safety of the plants.
Initial Actions by the NRC and the U.S. Nuclear Industry In September 2013, the NRC issued IN 2013-19 to inform industry of the quasi-laminar indications observed in the Belgian RPV forgings. Additionally, the NRC hosted a public meeting with industry and stakeholders on March 5, 2013, to discuss these indications (ADAMS Accession No. ML13066A725). The industry presented plans to the NRC staff to investigate the type of ultrasonic examination techniques used during construction and to perform a PFM evaluation of the structural integrity effect on U.S. reactors of potentially undiscovered quasi-laminar indications.
Subsequently, the industry published a report of its findings, titled, "Materials Reliability Program [MRP]: Evaluation of the Reactor Vessel Beltline Shell Forgings of Operating U.S. PWRs [Pressurized Water Reactors] for Quasi-Laminar Indications (MRP-367)"
(ADAMS Accession No. ML14064A411 (nonproprietary version)). The objectives of the report were two-fold: (1) to evaluate whether RPV forgings in U.S. plants were likely to have indications similar to those found in Deel 3 and Tihange 2 and (2) to evaluate the structural significance of indications if they did exist in an RPV. The report concluded that the ultrasonic techniques used during construction of U.S. vessels were capable of detecting quasi-laminar indications, and the reporting requirements would have caused the indications to be recorded
if they were present. The report included a PFM analysis of a set of conditions based on data from Deel 3 and Tihange 2. The industry concluded that even if quasi-laminar indications were present in a U.S. reactor vessel forging, the incremental increase in the vessel failure probability under pressurized thermal shock loading is negligible.
Summary of the NRC's Evaluation The NRC staff's evaluation consisted of reviewing the analyses performed by the Belgian licensee, as well as the two-pronged approach performed by the industry. Specifically, the NRC staff reviewed evaluations of the nondestructive examination records performed by the U.S. industry to determine the likelihood of the presence of the quasi-laminar indications in U.S. RPVs. Furthermore, the NRC staff reviewed the structural evaluations performed to determine the safety significance, even if the quasi-laminar indications were present. This was followed by applying the approach to risk-informed decision-making, as outlined in NRR Of LIC-504.
The Belgian licensee for Deel 3 and Tihange 2 performed deterministic flaw evaluations, which concluded that the quasi-laminar flaws observed in the RPV ring forgings were acceptable and did not compromise the structural integrity of the vessel. The Belgian licensee's PFM analyses using very conservative assumptions returned a crack initiation frequency below the NRC threshold for through-wall cracking frequency (TWCF). The NRC staff reviewed the analyses and found the analyses provided reasonable assurance that even if a significant number of quasi-laminar indications existed in an RPV forging, the forging would be fully capable of performing its safety function with an extremely low probability of failure. The Electric Power Research Institute (EPRI) MRP performed a PFM analysis and concluded that the TWCF associated with quasi-laminar indications was sufficiently low that the TWCF would meet NRC-risk criteria. The NRC staff performed a high-level review of the industry analyses
and concluded that the inputs were conservative with respect to flaw number and flaw size, at least relative to the information currently available concerning such flaws. The NRC staff has concluded that the EPRI analyses provided reasonable assurance that even if a significant number of quasi-laminar indications existed in an RPV forging, the forging would be capable of performing its safety function with an extremely low probability of failure.
The Pressurized Water Reactor Owners Group (PWROG) reviewed ultrasonic examinations performed during construction and determined the inspection equipment and techniques used at the time of construction were capable of detecting quasi-laminar indications.
Furthermore, the PWROG determined that the inspection recording criteria required the presence of quasi-laminar indications to be documented on nondestructive examination reports.
The PWROG submitted summaries of its assessments to the NRC staff in MRP-367. Based on its assessment of the available information related to construction ultrasonic examinations, the NRC staff agrees that the ultrasonic examination techniques would have detected quasi-laminar indications and, if present, indications would have been required to be recorded.
The PWROG retrieved ultrasonic testing inspection records and concluded that the records indicated no quasi-laminar indications were recorded during fabrication examinations for any vessel beltline ring forging in U.S. nuclear power plants. The NRC staff reviewed a sampling of those records and verified that no quasi-laminar indications were recorded in the reviewed reports. From these results, along with the PWROG's report that its record exams found no quasi-laminar indications, the NRC staff concludes that it is unlikely that significant numbers of quasi-laminar indications exist in U.S. RPV forgings.
In February 2015, publications in The Energy Daily and a press release by Greenpeace cited concerns raised by two materials science professors, Professor W. Bogaerts of the University of Leuven in Belgium and Professor D. MacDonald of the University of California at Berkeley. Professors Bogaerts and MacDonald took issue with the initial findings from the
Belgian licensee and the assessment by the Belgian regulator that concluded that the quasi-laminar indications have been present from the time Doel 3 and Tihange 2 were fabricated, and that they are not evolving (that is, increasing in number or getting bigger) over time. Professors Bogaerts and MacDonald have suggested that continued hydrogen ingress to the quasi-laminar indications could cause them to grow over time. The NRC staff is aware of this crack growth mechanism being common in some environments (for example, down-hole service in the oil and gas industry). However, the NRC staff is not aware of any current scientific information that would suggest that the conditions characteristic of nuclear pressure vessel service could generate partial-pressures of hydrogen that are high enough to cause such evolution during the operation of a reactor vessel.
Although these evaluations provide useful information for the two specific vessels in question, to evaluate the effects of the potential existence of quasi-laminar indications in RPV forgings in all U.S. vessels, the NRC staff used an analysis approach, based on PFM, and examined them within the context of the NRC's approach to risk-informed decision-making process described in NRR 01 LIC-504. For this review, the NRC staff considered the following five principles:
- Principle 1: The proposed change must meet the current regulations unless it is explicitly related to a requested exemption or rule change.
- Principle 2: The proposed change shall be consistent with the defense-in-depth philosophy.
- Principle 3: The proposed change shall maintain sufficient safety margins.
- Principle 4: When the proposed changes result in an increase in core damage frequency (CDF) or risk, the increases should be small and consistent with the intent of the Commission's Safety Goals.
- Principle 5: Monitoring programs should be in place.
The NRC staff considered three options to address, for the U.S. fleet of operating nuclear reactors, the recent operational experience from the Doel 3 and Tihange 2 reactors in Belgium:
- 1. Evaluate, communicate, and follow developments with no other required actions.
- 2. Initiate actions to require ultrasonic examination for quasi-laminar indications.
- 3. Immediate shutdown of potentially affected plants.
Consideration of Option 1: This option would entail acquiring information from the FANC, Electrabel, U.S. industry, and other relevant sources as it becomes available. The information would be evaluated to assess whether quasi-laminar indications present a significant challenge to RPV structural integrity. If the risk is sufficiently small, then no other action would be required for NRC licensees. As part of this option, the NRC staff would continue its review of the industry conclusions concerning the nonexistence of such flaws in U.S. plants and of the industry conclusion that the risk associated with these flaws, were they to exist, is small. The NRC staff would use material property information available from surveillance programs to assess the potential for greater-than-expected embrittlement revealed in some tests reported by Electrabel. In addition, the NRC staff would continue to assess new information as it becomes available and communicate new information, subject to limitations imposed by proprietary information rights and other nondisclosure agreements.
Consideration of Option 2: This option would encompass the actions in Option 1, but adds a development effort to require licensees to perform ultrasonic inspections of RPV forgings. The time frame for inspection would depend on the potential for indications to exist and the risk significance if they did exist. If the risk significance were high, as determined using risk metrics such as large early release frequency (LERF) being greater than or on the order of 1x10-4 /year, licensees may be required to perform inspections at the next refueling outage, or
even shut down and perform inspections immediately. If the risk significance were low, then licensees could wait to perform inspections during the next in-service examination outage.
Consideration of Option 3: This option would consist of shutting down some or all operating reactors until inspections and analyses are conducted to provide reasonable assurance that the calculated risk levels are acceptable. This option would be preferable if there was an immediate safety issue, such that the risk to operating plants was clearly demonstrated to be large and immediate.
As the estimated risk associated with quasi-laminar indications is less than 1x1 o- 6/year, far below the 1x1 o-4 /year LERF guideline in NRR 01 LIC-504, no immediate action was warranted and Option 3 was dismissed without an evaluation of the five principles of risk-informed decision-making.
Even if quasi-laminar indications similar to those discovered at Doel 3 and Tihange 2 existed in U.S. nuclear power plants, the indications are not expected to significantly affect RPV integrity under accident conditions. The basis for this conclusion is the industry analysis, as described in MRP-367 that indicates a vessel with 10 times as many indications as observed in the worst forging at Doel 3 would have a risk of TWCF less than 1x1 o-6/year, far below the 1x1 o-4 /year LERF guideline 2 in NRR 01 LIC-504 for immediate action and below the criteria for requiring additional action, contained in 10 CFR 50.61 a, "Alternate Fracture Toughness Requirements for Protection against Pressurized Thermal Shock Events."
Based on the NRR 01 LIC-504 evaluation, the NRC staff concluded no additional testing is necessary at this time. The NRC staff considered that there was not a significant risk 2 By equating TVVCF and LERF, it is possible to use the LERF risk guidelines in NRR 01 LIC-504 to conservatively identify an acceptable TVVCF. This is conservative because TVVCF is an estimate of the frequency of cracks that leak. However, not all leaks lead to core damage. Furthermore, core damage does not always lead to large early release. As a result, TVVCF is less than LERF. The fraction of time that core damage or large early release was prevented could be calculated, but it is conservative and computationally convenient to assume that all through wall cracks lead to large early release.
difference between Option 1 and Option 2. However, because Option 2 required physical activities associated with inspections, Option 2 requires increased expenditure of licensee resources and increased radiation exposure to plant personnel. Given two options having essentially equal risk with different resource needs, Option 1 was determined to be the more appropriate option. Given that no results were obtained that exceeded the NRC's risk guidelines, the NRC did not require all U.S. nuclear power plants be ultrasonically tested with the same or better technology. This addresses the petitioners first request, as well as, the petitioner's fourth request for testing of all operating reactors.
With respect to the petitioner's request-to take large borehole samples out of _both the Vermont Yankee and Kewaunee RPVs and transport them to a respected metallurgic laboratory for comprehensive offsite testing-the NRC staff notes that acquisition and subsequent testing of irradiated and aged plant material from decommissioned plants could be a valuable research activity that might offer useful scientific information related to understanding the progress of aging mechanisms. However, harvesting of reactor vessel material from plants that have been permanently shut down can be a complex and radiation-dose intensive effort. The NRC, through its Office of Nuclear Regulatory Research, has previously obtained samples appropriate for testing from shutdown plants. With respect to this request, the NRC may, in the future, seek to purchase samples. However, the identified facilities have ceased operations and there is no safety concern at those facilities that justifies enforcement-related action (i.e., to modify, suspend, or revoke the license) in order to for the NRC to have reasonable assurance of the adequate protection of public health and safety. Therefore, the NRC will not require Vermont Yankee or Kewaunee to remove large boreholes from their reactor vessels.
The Petitioner requested that the NRC issue a report and hold a public meeting on the vulnerabilities. The NRC staff considers the NRR 01 LIC-504 evaluation (ADAMS Accession
No. ML15282A218) as satisfying the request for the NRC to issue a report on the vulnerabilities.
Furthermore, the NRC already held a public meeting on this topic on March 5, 2013.
The following information addresses the remaining requested actions and questions raised by the petitioner that appear in bold italic type:
How has the average concentration of hydrogen in the coolant changed over the recent decades? Would an increasing concentration of hydrogen in the coolant lead to more hydrogen ions getting injected into the vessel iron?
The average concentration of hydrogen in coolant has not changed significantly over the past several decades in PWRs. Dael 3 and Tihange 2 are PWRs. With no change in average hydrogen concentration, there would be no change in hydrogen ingress into PWR pressure beltline steel.
The average concentration of hydrogen in boiling-water reactors (BWRs) has increased over the past several decades to concentrations closer to those used in PWRs. However, this does not result in an appreciable increase in the hydrogen content in BWR reactor pressure steel.
Does noble chemistry increase or decrease this kind of corrosion? Are there other chemicals added to the coolant that could make this kind corrosion worst?[sic]
Noble metal chemistry is a water chemistry technique used to suppress corrosion reactions that cause stress corrosion cracking in portions of BWR coolant systems. However, this does not result in an appreciable increase in the hydrogen content in BWR reactor pressure steel.
What are they talking about here: "However, as Belgian[sic] continues to debate the fate of the reactors, prolonged studies on the steel used in
the construction of the reactors revealed unprecedented embrittlement -
unusual swelling - that can compromise the integrity of the plant and possibly cause ruptures, spewing dangerous radioactive material equivalent to an atomic bomb."
The NRC and nuclear industry are well aware of embrittlement of the steel used in RPV fabrication. It is the primary factor that limits both the operable lifetime and the operating safety of the RPV. This embrittlement is caused by exposure to neutron irradiation, which occurs as an unavoidable consequence of the production of steam by nuclear fission to generate electricity. The nuclear industry uses several means to ensure that the RPV steel maintains adequate toughness throughout its operating lifetime. These are as follows:
- 1. The degree of neutron embrittlement is tracked throughout the operating lifetime of the plant. This is achieved using a surveillance program in which small samples (coupons) of the RPV steel are exposed to neutron irradiation inside the reactor.
- 2. The NRC establishes screening criteria on the degree of embrittlement allowed and on plant operating temperatures and pressures. Several NRC rules and regulatory guides, as well asSection XI of the American Society of Mechanical Engineers Code, collectively limit the combinations of embrittlement and operating temperatures and pressures so as to ensure safe nuclear power plant operations.
I understand all US nuclear plants have coupons and I consider them irrelevant to this problem.
The NRC staff recognizes the coupons are not relevant to the possibility of quasi-laminar indications.
Request the NRC coordinate with the Belgian Federal Agency for Nuclear Control (FANC).
The NRC staff is actively coordinating with FANC.
Request detailed inspection on the condition of the reactor cladding and an explanation of any defects.
By way of this director's decision and the references provided within, the NRC staff considers this request met.
Additionally, in the supplement dated September 9, 2015, the Petitioner requested the NRC staff to consider, "As part of the NRC review and approval of IPEC 3 [Indian Point Nuclear Generating Unit No. 3] Reactor Vessel Heatup and Coo/down curves, in ML15226A159 dated 9-3-15, was[sic] the possible adverse effects of this change considered in regard to IN 2013-19 Quasi Laminar Indications in RPV Forgings?"
The IPEC 3 RPV beltline is fabricated from rolled plates, not forgings. Because the manufacturing process used to produce plates differs from those used to produce forgings, any indications remaining after the manufacturing process in a vessel fabricated from plates would be laminar (that is, fully parallel to the plate surface), not quasi-laminar. As a result of this difference in orientation, any indications in the IPEC 3 would have no detrimental effect on the operating safety of the reactor vessel. Thus, the IPEC 3 Reactor Vessel Heatup and Cooldown curves are not affected by quasi-laminar indications.
Ill. Conclusion Based on the above, the NRR Director will not be instituting the proceeding requested by the petitioner, either in whole or in part. The NRC staff will continue to evaluate, communicate, follow developments and take appropriate action if deemed necessary.
As provided in 10 CFR 2.206(c), a copy of this director's decision will be fifed with the Secretary of the Commission for the Commission to review. As provided for by this regulation, the decision will constitute the final action of the Commission 25 days after the date of the decision unless the Commission, on its own motion, institutes a review of the decision within that time.
Dated at Rockville, Maryland, this day of 2016.
For the U.S. Nuclear Regulatory Commission.
William M. Dean, Director, Office of Nuclear Reactor Regulation
PKG: ML15090A484, L TR: ML15286A235, Proposed DD: ML15286A272, *via e-mail OFFICE NRR/DORL/LPLIV-2/PM NRR/DORL/LPLIV-2/LA NRR/DE RES*
NAME SKoenick PBlechman RHardies DRudland DATE 10/16/2015 10/16/2015 10/19/2015 11/06/2015 OFFICE QTE NRR/DORL/LPLIV-2/BC OGC NRR/DRP/PGCB NAME JDougherty* MKhanna RCarpenter LBanic DATE 11/03/2015 11/18/2015 12/7/15 11 /10/15 OFFICE NRR/DSS/PRB Chair NRR/DORL/D NMSS/DUWP/DD NRR/D NAME RTaylor ABoland JTappert APerskinko for WDean DATE 12/11/15 1/ 04 /16 1/ 05 /16 1/12/ 16
ML15198A091 and ML15286A003, respectively).
Enclosed is the NRC staff's proposed director's decision under Title 10 of the Code of Federal Regulations 2.206, "Requests for Action under this Subpart."
I request that you provide comments to me on any portions of the decision that you believe involve errors or any issues in the petition that have not been fully addressed. The NRC staff is making a similar request of the petitioner. The NRC staff will then review any comments that you and the petitioner provide and consider them in the final version of the director's decision, with no further opportunity to comment.
Please provide your comments within 14 calendar days from the date of this letter.
Sincerely, IRA/
John R. Tappert, Director Division of Decommissioning, Uranium Recovery and Waste Programs Office of Nuclear Material Safety and Safeguards Docket No. 50-305
Enclosure:
Proposed Director's Decision cc: Listserv DISTRIBUTION: OED0-15-00251 PUBLIC RidsOpaMail Resource TCarter, NMSS LPL4-2 R/F RidsOcaMailCenter Resource RHardies, NRR RidsNrrOd Resource RidsNrrMailCenter Resource PJehle, OGC RidsNrrDorl Resource RidsNmssOd Resource LBanic, NRR RidsNrrDorllp14-2 Resource RidsResOd Resource RTaylor, NRR RidsNrrPMKewaunee Resource RidsRgn3MailCenter Resource Steamshovel2002@yahoo.com RidsNrrLAPBlechman Resource RidsNmssDuwpRdb Resource RidsNrrPMVermontYankee Resource ADAMS A ccess1on Nos.: PKG ML15090A484 L TR ML15286A258 P ropose d DD : ML15286A272 *via. e-ma1 .,
OFFICE NRR/DORL/LPLIV-2/PM NRR/DORL/LPLIV-2/LA NRR/DE RES*
NAME SKoenick PBlechman RHardies DRudland DATE 10/16/2015 10/16/2015 10/19/2015 11 /06/2015 OFFICE QTE* NRR/DORL/LPLIV-2/BC OGC NRR/DRP/PGCB NAME JDougherty MKhanna RCarpenter LBanic DATE 11/03/2015 11/18/2015 12/7/15 11/10/15 OFFICE NRR/DSS/PRB Chair NMSS/DUWP/DD NAME RTaylor JTappert DATE 12/11/15 1/20/16