ML20003B534
| ML20003B534 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/22/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20003B532 | List: |
| References | |
| NUDOCS 8102120359 | |
| Download: ML20003B534 (4) | |
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UNITED STATES y,, y. ( (gg NUCLEAR REGULATORY COMMISSION
>:y WASHINGTON, D. C. 20555
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SVETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0. 60 TO FACILITY OPERATING LICENSE NO. DPR-50 AND EXEMPTION TO APPENDIX H OF 10 CFR PART 50 METROPOLITAN EDISON COMPANY THREE MILE ISLAND NUCLEAR STATION UNIT N0. 1 DOCKET NO. 50-289 Introduction i
By letter dated July 9,1980 (TLL 301), Metropolitan Edison Conpany (Met Ed) requested that an exemption to Appendix H of 10 CFR 50 Paragraph II.C. 4 be granted allowing the indefinite operation of the Three Mile Island Nuclear Station, Unit No.1 (TMI-1) with one of the remaining reactor vessel surveillance capsules being irradiated in Crystal River, Unit No. 3 (CR-3) rather than in TMI-2. Met Ed, by letter dated April 11,1980(TLL165),also requested approval of a proposed change to the Technical Specifications (TSs) consistent with the requested exemption.
The basis for this request is to provide an alternative to the capsule that is in TMI-2 reactor, which is inoperable and is not expected to restart in time to conduct an adequately integrated surveillance program.
In lieu of putting a backup surveillance capsule currently in storage in the TMI-1 pressure vessel, it will be placed in a host reactor, CR-3, for irradiation.
In addition, data from capsules from other irradiation programs will provide input to the TMI irradiation program. This overall program is an integrated surveillance program, in which all presently operating facilities with B&W i
l 177 fuel reactor assenblice are participating. TMI-l contains the B&N '177 fuel reactor assemblies and is considered a participating member.
Backaround Neutron irradiation causes the vessel material reference nil ductility temperature, RT to increase with time and the material fracture toughness properties to deba,sewithtime. These irradiated properties are used to establish pressure-temperature operating limits in accordance with Appendix G,10 CFR Part 50.
10 CFR Part 50, Appendix H, " Reactor Vessel Material Surveillance Program Requirements",
requires a material surveillance program for reactor vessels to monitor changes in the fracture toughness properties of ferritic materials in the vessel beltline region Under resulting from their exposure to neutron irradiation and thermal environment.
this program, fracture toughness test data are obtained from material specinens periodically withdrawn from the reactor vessel. Paragraph II.C.4 of Appendix H provides guidance for integrated surveillance prograas for multiple reactors located at a single site. However, Paragraph II.C.4 of Appendix H does not permit 8102120
i TMI-l,
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the sample of one reactor vessel material to be irradiated at another site.
The intent of this provision is to assure that reactor vessel sample material will be exposed to neutron energy spectra and the environmental conditions similar to that to which the reactor vessel is exposed during its service life.
i Discussion & Evaluation The original TMI-1 design included three reactor vessel surveillance specimen i
i holder tubes (SSHTS) located near the reactor inside vessel wall. The inte-t i
grated program for TMI-1 was approved as part of Amendment 29 issued April 22, 4
1977. Furthermore, similar integrated programs for other facilities with B&W 177 fuel assemblies were approved by the Comission, and exemptions were granted for those facilities with the host reactors at other sites.
To date, the status of the TMI-l surveillance program is that one surveillance capsule has been removed from the TMI-l reactor vessel and tested (removed prior to the igtiatign of the integrated program).
This capsule received a fluence of 1.1 x 10 n/cm. Test results showed that weld metal (designated WF-25) is the limiting vessel material, One TMI-1 capsule was installed and still exists in the TMI-2 reactor vessel. Tne remainfng four TMI-l capsules are in storage.
Due to the'Tt11-2 incident,it is anticipated that TMI-2 will not be operational for 4
at least several years. Therefore, the licensee, by letter dated April 11, 1980, requested an amendment to the TSs of TMI-l that would permit one of the TMI-l capsules currently in storage to be irradiated in the CR-3 reactor vessel. Because this request resulted in having the host reactor offsite for the TMI-l integrated surveillance program, Met Ed, by letter dated July 9,1980, requested an exemption from 10 CFR Appendix H.
The licensee proposed that a capsule now 1.n storage be placed in the CR-3 vessel at the end of the second cycle and withdrawn at the end of the fifth cyge. ~ Dyring this period, the capsule is expected to receive a fluence of 8.2 'x 10 n/cm. This fluence is approximately equal to the fluence at the 1/4T location in the TMI-1 reactor vessel wall at 22 effective full power years (EFPY). The TMI-l surveillance weld metal, WF-25, is also contained in a B&W research capsule being irradiated in CR-3.
This capsule contains not only tensile and Charpy specimens but also several sizes of compact fracture toughness specimens. The test results on this capsule should be available by the end of IM.
Finally, irradiated data on WF-25 will' be i
obtained from a Naval Research Laboratory (NRL) program sponsored by NRC. This.
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data should be available in the early 1980s.
In regard to installing the capsule in TMI-1, part of Amendment 29 included studies of methods to install the redesigned SSHTS in Tt!I-1..These studies indicated that substantial difficulties would be experienced primarily because -
precision machinery alignment and-inspection must be performed remotely and under water. Although such problems do' not in themselves justify relief from a requirement to reinstall the SSHTS in TMI-1, they would cause signi-1 ficant radiation to personnel. Based on experience in removing the SSHTS at TMI-l i
and other reactors, B&W estimated that installing SSHTS in irradiated reactors i-would result in personnel exposure of about 100 man rem / reactor. The licensee.
reviewed this matter based on the existing conditions of TMI-l_ (i.e., shutdown for an extended period) and concluded an exposure of about 100 man rem would be applicable to the present conditions at TMI-1. This is due to-the increased fluence that the reactor internals have been exposed to since the initial study has been t
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made, which on the other hand would be offset by the decay of the short half life isotopes due to the long shutdown period. This matter was discussed with the licensee and the staff agrees with this assessment.
The B&W integrated surveillance program was initiated in 1977.
Since then one capsule originally belonging to Oconee 1, 2 and 3, Arkansas 1 and CR-3 reactor vessels has been removed from the host vessel and tested. A second capsule for Oconee 1, 2 and 3 and Arkansas 1 is currently being evaluated.
Data generated from these capsules are satisfactory. The integrated surveillance program is con-sidered to be working as planned in monitoring radiation effects of the pressure vessel materials. Therefore, there is no need at this time to consider a limiting period to the exemption.
From our review, we conclude that the THI-l surveillance progran supplementea oy data from NRL and B&W research programs,will provide sufficient data to monitor radiation damage on the TMI-l reactor vessel weld metal throughout service life.
Data on the TMI-l vessel base metal will be generated only from the TMI-1 surveil-lance capsules. Since base metal is not the limiting material, we conclude that the data from the surveillance program will be sufficient to monitor radiation damage on base metal.
Furthemore, we have determined that the dimensional design, the themal environment and the neutron flux distribution and the energy spectrum of the CR-3 and THI-l reactor vessels are so similar that changes in mechanical properties due to irradiation effects will not be affected whether capsules are irradiated in CR-3 or in TMI-1. We find that irradiating a TMI-l surveillance capsule in CR-3 does not reduce the effectiveness of the surveillance program and the intent of the provisions of Paragraph II.C.4 of Appendix H are being met.
Based on the above, we conc'ude that the proposed program to irradiate a TMI-l surveillance capsule in the CR-3 reactor vessel is acceptable. We find that an exemption to the provisions of Paragraph II.C.4 of Appendix H of 10 CFR Part 50 is authorized by law and will not endanger life or property or the comon defense and security. Moreover, since the exemption allowing irradiation of the TMI-l surveillance capsule in CR-3 will avoid approximately 100 man-rems of occupational exposure that would result if the exemption were not granted and the surveillance capsule had to be inserted into the TMI-1 vessel and since the exemption will allow the completion of the pressure vessel material sur-veillance program for TMI-l without such an occupational dose, we find that the exemption is in the public interest. Accordingly, we find that the exemption i
should be granted.
I The existing TSs permit the reactor surveillance program for TMI-l to be irradiated only in TMI-2. We agree with Met Ed that the surveillance prcgram cannot be continued in TMI-2 due to its present inoperable condition which is expected to exist for several years. The proposed TS change will permit a backup surveillance capsule currently in storage to be irradiated in the CR-3 l
reactor vessel. We find this change acceptable because this capsule containing l
reactor vessel sample material of TMI-1, when irradiated in CR-3, will be exposed to the neutron energy spectra and environmental conditions similar to i
that to which the TMI-1 reactor vessel is exposed during its service life.
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Environmental Consideration e in We have determined that these amendments do not authorize a chanc ef fluent types or total anounts nor an increase in power level and will not result in any significant environmental impact. Having made this detennination, we have further concluded that these amendments involve an action which is insignificant from the standpoint of environmental f
impact and pursuant to 10 CFR 551.5(d)(4) that an environmental impact statement, negative declaration or environmental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Comission's regulations and the issuance of these amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Moreover, based on the considerations discussed above, we conclude that an exemption from Paragraph II.C.4 of Appendix H of 10 CFR Part 50, permitting irradiation of a TMI-l surveillance capsule in CR-3,is in accordance with law, will not endanger life or property or the cormon defense and security and is otherwise in the public interest.
Dated:
January 22, 1981 l
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