Source: http://www.nrc.gov/reading-rm/doc-collections/cfr/part050/part050-0066.html
Timestamp: 2016-12-10 12:45:29
Document Index: 662450439

Matched Legal Cases: ['§ 50', '§ 50', '§ 50', 'art 50', '§ 20', '§ 50', '§ 50', '§ 50', '§ 50']

NRC: 10 CFR 50.66 Requirements for thermal annealing of the reactor pressure vessel.
Part Index > § 50.66 Requirements for thermal annealing of the reactor pressure vessel.
(a) For those light water nuclear power reactors where neutron radiation has reduced the fracture toughness of the reactor vessel materials, a thermal annealing may be applied to the
reactor vessel to recover the fracture toughness of the material. The use of a thermal annealing treatment is subject to the requirements in this section. A report describing the
licensee's plan for conducting the thermal annealing must be submitted in accordance with § 50.4 at least three years prior to the date at which the limiting fracture toughness criteria
in § 50.61 or appendix G to part 50 would be exceeded. Within three years of the submittal of the Thermal Annealing Report and at least thirty days prior to the start of the thermal
annealing, the NRC will review the Thermal Annealing Report and make available the results of its evaluation at the NRC Web site, http://www.nrc.gov. The licensee may begin the
thermal anneal after:
(b) Thermal Annealing Report. The Thermal Annealing Report must include: a Thermal Annealing Operating Plan; a Requalification Inspection and Test Program; a Fracture
Toughness Recovery and Reembrittlement Trend Assurance Program; and Identification of Unreviewed Safety Questions and Technical Specification Changes.
(1) Thermal Annealing Operating Plan.
(i) A detailed description of the pressure vessel and all structures and components that are expected to experience significant thermal or stress effects during the thermal annealing
(ii) An evaluation of the effects of mechanical and thermal stresses and temperatures on the vessel, containment, biological shield, attached piping and appurtenances, and adjacent
equipment and components to demonstrate that operability of the reactor will not be detrimentally affected. This evaluation must include:
(A) Detailed thermal and structural analyses to establish the time and temperature profile of the annealing operation. These analyses must include heatup and cooldown rates, and
must demonstrate that localized temperatures, thermal stress gradients, and subsequent residual stresses will not result in unacceptable dimensional changes or distortions in the
vessel, attached piping and appurtenances, and that the thermal annealing cycle will not result in unacceptable degradation of the fatigue life of these components.
(B) The effects of localized high temperatures on degradation of the concrete adjacent to the vessel and changes in thermal and mechanical properties, if any, of the reactor vessel
insulation, and on detrimental effects, if any, on containment and the biological shield. If the design temperature limitations for the adjacent concrete structure are to be exceeded
during the thermal annealing operation, an acceptable maximum temperature for the concrete must be established for the annealing operation using appropriate test data.
(iii) The methods, including heat source, instrumentation and procedures proposed for performing the thermal annealing. This shall include any special precautions necessary to
minimize occupational exposure, in accordance with the As Low As Reasonably Achievable (ALARA) principle and the provisions of § 20.1206.
(A) The thermal annealing time and temperature parameters selected must be based on projecting sufficient recovery of fracture toughness, using the procedures of paragraph (e) of
this section, to satisfy the requirements of § 50.60 and § 50.61 for the proposed period of operation addressed in the application.
(B) The time and temperature parameters evaluated as part of the thermal annealing operating plan, and supported by the evaluation results of paragraph (b)(1)(ii) of this section,
represent the bounding times and temperatures for the thermal annealing operation. If these bounding conditions for times and temperatures are violated during the thermal
annealing operation, then the annealing operation is considered not in accordance with the Thermal Annealing Operating Plan, as required by paragraph (c)(1) of this section, and
the licensee must comply with paragraph (c)(2) of this section.
(2) Requalification Inspection and Test Program. The inspection and test program to requalify the annealed reactor vessel must include the detailed monitoring, inspections, and
tests proposed to demonstrate that the limitations on temperatures, times and temperature profiles, and stresses evaluated for the proposed thermal annealing conditions of paragraph
(b)(1)(iv) of this section have not been exceeded, and to determine the thermal annealing time and temperature to be used in quantifying the fracture toughness recovery. The
requalification inspection and test program must demonstrate that the thermal annealing operation has not degraded the reactor vessel, attached piping or appurtenances, or the
adjacent concrete structures to a degree that could affect the safe operation of the reactor.
(3) Fracture Toughness Recovery and Reembrittlement Trend Assurance Program. The percent recovery of RTNDT and Charpy upper-shelf energy due to the thermal annealing
treatment must be determined based on the time and temperature of the actual vessel thermal anneal. The recovery of RTNDT and Charpy upper-shelf energy provide the basis for
establishing the post-anneal RTNDT and Charpy upper-shelf energy for each vessel material. Changes in the RTNDT and Charpy upper-shelf energy with subsequent plant operation
must be determined using the post-anneal values of these parameters in conjunction with the projected reembrittlement trend determined in accordance with paragraph (b)(3)(ii) of
this section. Recovery and reembrittlement evaluations shall include:
(i) Recovery Evaluations. (A) The percent recovery of both RTNDT and Charpy upper-shelf energy must be determined by one of the procedures described in paragraph (e) of this
section, using the proposed lower bound thermal annealing time and temperature conditions described in the operating plan.
(B) If the percent recovery is determined from testing surveillance specimens or from testing materials removed from the reactor vessel, then it shall be demonstrated that the
proposed thermal annealing parameters used in the test program are equal to or bounded by those used in the vessel annealing operation.
(ii) Reembrittlement Evaluations. (A) The projected post-anneal reembrittlement of RTNDT must be calculated using the procedures in § 50.61(c), or must be determined using the
same basis as that used for the pre-anneal operating period. The projected change due to post-anneal reembrittlement for Charpy upper-shelf energy must be determined using the
same basis as that used for the pre-anneal operating period.
(B) The post-anneal reembrittlement trend of both RTNDT and Charpy upper-shelf energy must be estimated, and must be monitored using a surveillance program defined in the
Thermal Annealing Report and which conforms to the intent of Appendix H of this part, "Reactor Vessel Material Surveillance Program Requirements."
(4) Identification of Unreviewed Safety Questions and Technical Specification Changes. Any changes to the facility as described in the updated final safety analysis report
constituting unreviewed safety questions, and any changes to the technical specifications, which are necessary to either conduct the thermal annealing or operate the nuclear power
reactor following the annealing, must be identified. The section shall demonstrate that the Commission's requirements continue to be complied with, and that there is reasonable
assurance of adequate protection to the public health and safety following the changes.
(c) Completion or Termination of Thermal Annealing. (1) If the thermal annealing was completed in accordance with the Thermal Annealing Operating Plan and the Requalification
Inspection and Test Program, the licensee shall so confirm in writing to the Director, Office of Nuclear Reactor Regulation. The licensee may restart its reactor after the
requirements of paragraph (f)(2) of this section have been met.
(2) If the thermal annealing was completed but the annealing was not performed in accordance with the Thermal Annealing Operating Plan and the Requalification Inspection and
Test Program, the licensee shall submit a summary of lack of compliance with the Thermal Annealing Operating Plan and the Requalification Inspection and Test Program and a
justification for subsequent operation to the Director, Office of Nuclear Reactor Regulation. Any changes to the facility as described in the updated final safety analysis report which
are attributable to the noncompliances and constitute unreviewed safety questions, and any changes to the technical specifications which are required as a result of the
noncompliances, shall also be identified.
(i) If no unreviewed safety questions or changes to technical specifications are identified, the licensee may restart its reactor after the requirements of paragraph (f)(2) of this section
(ii) If any unreviewed safety questions or changes to technical specifications are identified, the licensee may not restart its reactor until approval is obtained from the Director, Office
of Nuclear Reactor Regulation and the requirements of paragraph (f)(2) of this section have been met.
(i) If the partial annealing was otherwise performed in accordance with the Thermal Annealing Operating Plan and relevant portions of the Requalification Inspection and Test
Program, and the licensee does not elect to take credit for any recovery, the licensee need not submit the Thermal Annealing Results Report required by paragraph (d) of this section
but instead shall confirm in writing to the Director, Office of Nuclear Reactor Regulation that the partial annealing was otherwise performed in accordance with the Thermal
Annealing Operating Plan and relevant portions of the Requalification Inspection and Test Program. The licensee may restart its reactor after the requirements of paragraph (f)(2) of
(ii) If the partial annealing was otherwise performed in accordance with the Thermal Annealing Operating Plan and relevant portions of the Requalification Inspection and Test
Program, and the licensee elects to take full or partial credit for the partial annealing, the licensee shall confirm in writing to the Director, Office of Nuclear Reactor Regulation that
the partial annealing was otherwise performed in compliance with the Thermal Annealing Operating Plan and relevant portions of the Requalification Inspection and Test Program.
The licensee may restart its reactor after the requirements of paragraph (f)(2) of this section have been met.
(iii) If the partial annealing was not performed in accordance with the Thermal Annealing Operating Plan and relevant portions of the Requalification Inspection and Test Program,
the licensee shall submit a summary of lack of compliance with the Thermal Annealing Operating Plan and the Requalification Inspection and Test Program and a justification for
subsequent operation to the Director, Office of Nuclear Reactor Regulation. Any changes to the facility as described in the updated final safety analysis report which are attributable
to the noncompliances and constitute unreviewed safety questions, and any changes to the technical specifications which are required as a result of the noncompliances, shall also be
(A) If no unreviewed safety questions or changes to technical specifications are identified, the licensee may restart its reactor after the requirements of paragraph (f)(2) of this section
(B) If any unreviewed safety questions or changes to technical specifications are identified, the licensee may not restart its reactor until approval is obtained from the Director,
Office of Nuclear Reactor Regulation and the requirements of paragraph (f)(2) of this section have been met.
(d) Thermal Annealing Results Report. Every licensee that either completes a thermal annealing, or that terminates an annealing but elects to take full or partial credit for the
annealing, shall provide the following information within three months of completing the thermal anneal, unless an extension is authorized by the Director, Office of Nuclear
Reactor Regulation:
(e) Procedures for Determining the Recovery of Fracture Toughness. The procedures of this paragraph must be used to determine the percent recovery of RTNDT, Rt, and percent
recovery of Charpy upper-shelf energy, Ru. In all cases, Rt and Ru may not exceed 100.
(1) For those reactors with surveillance programs which have developed credible surveillance data as defined in § 50.61, percent recovery due to thermal annealing (Rt and Ru) must
be evaluated by testing surveillance specimens that have been withdrawn from the surveillance program and that have been annealed under the same time and temperature
conditions as those given the beltline material.
(f) Public information and participation. (1) Upon receipt of a Thermal Annealing Report, and a minimum of 30 days before the licensee starts thermal annealing, the Commission
(i) Notify and solicit comments from local and State governments in the vicinity of the site where the thermal annealing will take place and any Indian Nation or other indigenous
people that have treaty or statutory rights that could be affected by the thermal annealing,
(ii) Publish a notice of a public meeting in the FEDERAL REGISTER and in a forum, such as local newspapers, which is readily accessible to individuals in the vicinity of the site, to
solicit comments from the public, and
(2) Within 15 days after the NRC's receipt of the licensee submissions required by paragraphs (c)(1), (c)(2) and (c)(3)(i) through (iii) of this section, the NRC staff shall make
available at the NRC Web site, http://www.nrc.gov, a summary of its inspection of the licensee's thermal annealing, and the Commission shall hold a public meeting:
Effective Date Note: See 64 FR 53582, Oct. 4, 1999, for effectiveness of Sec. 50.66 (b) introductory text, paragraphs (b)(4), (c)(2), and (c)(3)(iii).
6 For those cases where materials are removed from the beltline of the pressure vessel, the stress limits of the applicable portions of the ASME Code Section III must be satisfied, including consideration of fatigue and corrosion, regardless of the Code of record for the vessel design.