ML20205C376
| ML20205C376 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 03/26/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20205C351 | List: |
| References | |
| NUDOCS 9904010173 | |
| Download: ML20205C376 (5) | |
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UNITED STATES
- 5 NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 308s64001 49*****
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PROPOSED EXEMPTION TO 10 CFR PART 50. APPENDIX A.
GENERAL DESIGN CRITERION 19 PERRY NUCLEAR POWER PLANT. UNIT 1 FIRSTENERGY NUCLEAR OPERATING COMPANY L
DOCKET NO. 50-440
1.0 INTRODUCTION
By letter dated December 3,1998, the licensee for the Perry Nuclear Power Plant (PNPP),
Unit 1, requested that the NRC exempt the facility from the control room dose acceptance criterion of 10 CFR Part 50, Appendix A, General Design Criterion (GDC) 19, " Control Room."
The exemption request would permit use of a total effective dose equivalent (TEDE) acceptance criterion of 5-rem in place of the "5 rem whole body, or its equivalent to any part of the body" dose acceptance criterion that is currently specified in GDC 19. The TEDE dose guidelines, which are needed to support revised accident source term applications, are not currently provided in regulations goveming operating reactors.
2.0 REGULATORY REQUIREMENTS Pursuant to 10 CFR Part 50, Appendix A, GDC 19, alllight-water nuclear power plants must have a control room "from which actions can be taken to operate the nuclear power unit safely under normal conditions and to maintain it in a safe condition under accident conditions, including loss-of-coolant accidents. Adequate radiation protection shall be provided to permit 4
access and occupancy of the control room under accident conditions without personnel receiving radiation exposures in excess of 5 rem whole body, or its equivalent to any part of the body, for the duration of the accident."
3.0 BACKGROUND
4 Regulatory guidance on accident source terms was originally published in 1962 by the U.S.
Atomic Energy Commission in Technical Information Document (TID) 14844, " Calculation of Distance Factors for Power and Test Reactors." The accident source term is used to characterize the postulated release of fission products from the core of a light-water reactor into the containment atmosphere during an accident. This source term is used to evaluate the radiological consequences of design-basis accidents (DBAs) to determine compliance with various requirements.
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The staff's methods for calculating accident doses were developed to be consistent with the TID-14844 source term and the whole body and thyroid dose acceptance criteria (10 CFR Parts 50 and 100 and NUREG-0800). Under the current regulatory framework for operating plants, the noble gas and radiolodine portions of the TID source are assumed to be released immediately to the containment atmosphere at the start of a postulated accident. The chemical form of the radio?odine is assumed to be predominantly elemental, and half of the radioiodine inventory is assumed to be unavailable for release because of plateout. Doses are calculated at the exclusion area boundary for the first 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and at the bw population zone for the course of the accident, which is assumed to continue for 30 days. Whole-body doses are calculated mainly from the noble gas portion of the source term, and thyroid doses are calculated from the i
radioiodines. In practice, the thyroid dose has almost always been the limiting calculation for power plants. The entire TID source term, including 1 percent of the solids, is used for the DBA radiation environmental qualification of electrical and mechanical equipment, post-accident shielding, and Three Mile Island related requirements. This regulatory framework provides a consistent analytical approach for evaluating the potential consequences for DBAs.
More than a decade of research has led to an enhanced understanding of the timing, magnitude, and chemical form of fission product releases following postulated DBAs. The results of this work have been summarized in NUREG-1465, " Accident Source Terms for Light-Water Nuclear Power Plants" (issued in February 1995), and in a number of related research reports. NUREG 1465 presents a representative severe-accident source term (referred to as the revised accident source term) for both boiling-water and pressurized-water reactors. For DBAs, the revised accident source term is comparable to the TID source term; however, it y
contains a more realistic description of release timing and radionuclide composition. The revised accident source term describes different release fractions of core inventory, chemical and physical forms of important species, and natural removal processes that reduce the quantity
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of radioactive material that may be released to the environment.
There have also been significant developments in the principles and scientific knowledge underlying standards for systems of radiation dose limitation and asses"nent. These
- developments include not only updated scientific information on radionuclide uptake and metabolism but also reflect changes in the basic philosophy of radiation protection. In 1991, the i
NRC revised 10 CFR Part 20, " Standards for Protection Against Radiation," to reflect these developments. The revision to 10 CFR Part 20 provided for the use of the TEDE acceptance criteria, which considers the effects of doses to all body organs.
l On November 25,1996, the staff issued SECY-96-242, "Use of the NUREG-1465 Source Term at Operating Reactors," thus informing the Commission of its approach to allow voluntary use of the revised accident source term at operating plants. In the SECY paper, the staff recommended that dose guidelines be expressed in terms of TEDE if a licensee elects to use the revised accident source term insights for DBA evaluations.
in the SECY paper, the staff recommended use of a 5-rem TEDE criterion for control room doses. However, the accident dose guidelines specified in 10 CFR Part 50, Appendix A, GDC 19, were not changed. The SECY paper recognized that exemptions may be required to permit l
the first operating plants to implement the revised accident source term. Long-range plans addressed the need for rulemaking, which would prevent the need for future exemptions. The 1
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Commission ultimately accepted the staff's recommendations in a staff requirements m'emorandum dated February 12,1997, in which the Commission directed the staff to incorporate TEDE into rulemaking.
i By letter dated August 27,1996, the licensee submitted proposed technical specification changes using the revised accident source term from NUREG-1465 and the Nuclear Energy Institute document entitled, " Generic Framework for Application of Revised Accident Source Term to Operating Plants." Using the TEDE dose acceptance criteria, the licensee proposes to 2
eliminate the main steam isolation valve (MSIV) leakage control system and increase the allowable leakage rates for the MSIVs. In response to a staff request for additionalinformation dated July 23,1998, addressing the need to seek an exemption from the dose acceptance criteria of GDC 19, the licensee submitted a proposed exemption to 10 CFR Part 50, Appendix A, GDC 19, on December 3,1998.
l 4.0 EVALUATION f
The proposed exemption request supports the Commission's directive for using the TEDE dose acceptance criteria in a revised accident source term application. The current regulatory guidance uses whole body and thyroid dose acceptance criteria. The PNPP license request to revise the main steamline leakage requirements and to eliminate the MSIV leakage control system is based on reanalysis of the design-basis loss-of-coolant accident using the revised j
accident source term from NUREG-1465. In SECY-96-242, the staff informed the Commission l
of its approach to allow the use of the revised accident source term described in NUREG-1465 i
at operating plants. In this paper, the staff described its plans to review plant applications for use of the revised accident source terms. The Commission approved these plans and u,rected j
the staff to commence rulemaking and requested the use of a TEDE dose methodology in the implementation.
For DBA applications, the revised accident source term is comparable to the TID-14844 source 3
i term with regard to the magnitude of the noble gas and radiciodine release fractions. In addition, the revised accident source term provides a more representative description of the j
radionuclide composition and release timing. Therefore, the staff concludes that the TEDE methodology provides an alternate means of meeting the current regulatory requirement.
5.0 CONCLUSION
Pursuant to 10 CFR 50.12, the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of 10 CFR Part 50 when (1) the exemptions are authorized by law, will not present an undue risk to public health or safety, and i
are consistent with the common defense and security, and (2) when special circumstances are present. Special circumstances are present whenever, according to 10 CFR 50.12(a)(2)(ii),
" Application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule." The NRC staff examined the licensee's rationale to support the exemption request and concluded that the i
use of the TEDE dose acceptance criteria for the control room would meet the underlying intent of the regulations. The licensee's request for the exemption under the special circumstances of j
10 CFR 50.12(a)(2)(ii) was found to be appropriate. The staff concludes that application of the i
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- j control room dose acceptance criteria of GDC 19 is not necessary to achieve the underlying purpose of the rule because the staff considers the TEDE methodology as an acceptable means of meeting the current regulatory requusment.
Principal Contributor: Douglas Pickett Date:- March 26, 1999 i
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3[2% 7 T MEMORANDUlf TO:
' Rules and Directives Branch Division of Administrative Services Offbe of Administration FROM:
Office of Nuclear Reactor Regulation
SUBJECT:
{ Yy, 1 One signed original c,f the federalRegister Notice identified below is attached for your transmittal to the Office of the Federv 9egister for publication. Additional conformed copies (
) of the Notice are enclosed for w.. use.
Notice of Receipt of Application for Construction Permitis) and Operating License (s).
Notice of Receipt of Partial Application for Construction Permit (s) and Facility License (s):
Time for submission of Views on Antitrust matters.
Notice of Consideration of issuance of Amendment to Facility Operating License. (Cal1 with 30-day insert date).
Notice of Receipt of Application for Faci!;ty License (s); Notice of Availability of Applicant's Environmental Report; and Notice of Cransideration of issuance of Facility License (s) and Notice of Opportunity for Hearing.
Notice of Availability of NRC Draft / Final Environmental Statement.
Notice of Limited Work Authorization.
Notics of Availability of Safety Evaluation Report.
Notice of issuance of Construction Permit (s).
t, Notice of issuance of Facility Operating License (s) or Amendment (s).
Order.
Exemption.
Notice of Granting Exemption.
Environmental Assessment.
[, Notite of Preparation of Environmental Assessment.
l Receipt of Petition for Director's Decision Under 10 CFR 2.206.
' Issuance of Final Director's Decision Under 10 CFR 2.206.
O. w DOCKET NO. b.P SN Attachment (s): As stated
Contact:
ee% h Telephone:
DOCUMENT NAME:
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