ML20210T152
| ML20210T152 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 02/09/1987 |
| From: | Miraglia F Office of Nuclear Reactor Regulation |
| To: | GENERAL PUBLIC UTILITIES CORP. |
| Shared Package | |
| ML20210T117 | List: |
| References | |
| NUDOCS 8702180083 | |
| Download: ML20210T152 (8) | |
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4 UNITED STATES FUCLEAR REGULATORY COMMISSION In the Matter of ) 6
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GENERAL PUBLIC UTILITIES NUCLEAR ) Docket No. 50-320 CORPOPATION
)
(Three Mile Island Nuclear Station )
Unit 2) )
EXEMPTION I.
GPU Nuclear Corporation, Metropolitan Edison Company, Jersey Central Power and Licht Company and Pennsylvania Electric Company (collectively, the licensee) are the holders of Facility Operating Licensing No. DPR-73, which had authorized operation of the Three Mile Island Nuclear Station, Unit 2 (TMI-2) at power levels up to 2772 megawatts thermal. The facility, which is located in Londonderry Township, Dauphin County, Pennsylvania, is a pressurized water reactor previously used for the commercial generation of electricity.
By Order for Modification of License, dated July 20, 1979, the licensee's authority to operate the facility was suspended and the licensee's authority was limited to maintenance of the facility in the present shutdown cooling mode (44 Fed. Reg. 45271). By further Order of the Director, Office of Nuclear Reactor Regulation, dated February 11, 1980, a new set of formal license requirements was imposed to reflect the post-accident condition of the facility and to assure the continued maintenance of the current safe, stable, long-term cooling condition of the facility (45 Fed. Reg.11292). The license provides, among other things, that it is subject to all rules, regulations and Orders of the Commission now or hereafter in effect.
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II.
ByletterdatedDecember10,1886,Lthelicenseerequestedexemptionsfromthe requirements of.10 CFR 50, Appendix A, General Design Criteria '(GDC) 17 and 19, concerning electric power systems and control room habitebility. Specifically, -
GDC 17 requires that an. onsite electric power system and an offsite electric power ~ system shall be provided to permit functioning of structures, systems and -
components important to safety. GDC 17 further requires that the safety func--
tion for each , system (assuming the other system is not functioning) should be to provide sufficient capacity and capability to assure that (1) specified accepta.le fuel desian limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents. Addi-tionally, GDC 17 specifies that both onsite and offsite electric power systems should have sufficient independence and redundancy to perfom their safety functions assuming a single failure. As relevant to the licensee's request, GDC 19 requires that a control room shall be provided 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 n _
loss-of-coolant accidents. GDC 19 further reouires that adequate radiation protection shall be provided to permit 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. Under the TMI-2 operating license, control room t
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habitability during accident conditions has been assured through thh operability of the control room emergency air cleanup system. In the unlikely event of an accident with concurrent loss of offsite power (LOOP), the. diesel generators would provide onsite emergency backup power to assure the operability of the system.
III.
The licensee has requested exemption from the indicated General Design Criteria in conjunction with license amendment requests submitted by letters dated June 18, 1985 and July 31, 1985, as modified by letters dated February 26, 1986 and May 20, 1986 and in additional discussions with the staff. The staff has reviewed the safety evaluations submitted in support of the proposed license amendments, which also provide the bases for the licensee's exemption requests.
Specifically, the licensee proposes to delete all license requirements for availability and operability of the Class IE diesel generators. As a result of previous amendments to the facility license to reflect the unique post-accident status of the TMI-2 facility, the control room emergency air clr nup system is the only remaining system requiring power from the onsite diesel generators.
Consequently, the licensee also proposes to delete the license requirement for onsite emergency backup power to this system.
TMI-2 is currently in a long-tem cold shutdown for accident recovery and defueling. Short-lived fission products which make up the preponderance of the source term in operating reactors have decayed to negligible levels.
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, Decay heat is less than 10 kilowatts and forced cooling of the coret has not been required or used since 1981. . Core cooling and criticality control are provided by maintaining a sufficient volume of borated water in the RCS.
Natural convective heat loss from the RCS directly to the reactor building atmosphere provides sufficient decay heat removal capability. In the unlikely event of the maximum credible TMI-2 loss of coolant accident, previously analyzed by the staff, sufficient borated water would be provided by passive, gravity feed from the borated water storage tank to keep the core covered for a minimum of 10 days. The standby reactor building sump recirculation system would be made operational during this time if needed to maintain core coverage for a longer period.
The types of accidents possible at TMI-2 during the cleanup phase (long-term cold shutdown) differ significantly from those possible in an operating reactor.
The staff and the licensee have evaluated a broad spectrum of potential accident scenarios possible at TMI-2 during the cleanup phase. These included liquid -
spills, fires, canister drops, and loss of coolant accidents. The source terms from these accident scenarios are much smaller than those associated with postulated accidents at operating power reactors. Additionally, none of these accidents would be caused by a LOOP and thus are extremely unlikely to occur simultaneously with the unavailability of the control room emergency air cleanup system.
TMI-1, which is adjacent to TMI-2, is in a normal operating cycle for power reactors with periods of power operation periodically interrupted by variable
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s length shutdowns for refueling, maintenance and repairs. ' A severe pccident at~
..TMI-1 while it is at power could generate a source term which could affect TMI-2' control room habitability. It is very' improbable that this type of accident would occur and even more unlikely that it would be coincident with a j- loss of offsite power to TMI-2. If there were no coincident TMI-2 LOOP, the TMI-2 control room emergency air cleanup system would function normally.
4 The licensee has committed to terminate all recovery activities and place ,
i systems in a safe, stable configuration at TFI-2 during an emergency event at TMI-1. These activities include core alterations, RCS water processing, 4
transfer of fuel bearing canisters and casks, and movement of heavy loads.
\ While an accident at TMI-1 could affect habitability in TMI-?, it would not '
i cause equipment failures and additional accidents to occur. at TMI-2. No active I
components are required to maintain the current safe shutdown of TMI-2. With recovery activities terminated, periodic monitoring of TMI-2 is all that is required. No effect on plant safety would occur due to temporary inaccess-ibility of the TMI-2. control room. The staff has previously determined that offsite AC power can be restored within five hours. With the restoration of offsite power, the TMI-2 control room emergency air cleanup system would again become operable and personnel could again monitor activities from the control
,. room. Although not required, short-term access to the TFI-2 control room could be provided by use of self contained breathing apparatus.
'The st'aff has evaluated the potential accident scenarios discussed above relative to the requirements for control room habitability specified in i
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GDC 19. We conclude that it is highly probable that in the event 0F an accident at TMI-1 or TMI-2, the TMI-2 control room emergency air cleanup system will be operable without relying on onsite backup emergency power sources, and thus habitability of the TMI-2 control room will be ensured in
-accordance with GDC 19. However, in the extremely unlikely event that a severe accident at Unit 1 occurs coincident with loss of offsite power tn Unit 2, the Unit 2 control room could, if necessary, be evacuated without affectina the licensee's ability to maintain the TMI-2 facility safely shutdown. Accordingly, a partial exemption from GDC 19 during a LOOP is ,iustified since no action of personnel in the TMI-2 control room would be required to maintain the plant in a safe shutdown condition for the period of time necessary to restore power.
Except for such occurrences, the licensee will continue to comply with the provisions of GDC 19.
f Since THI-2 can be maintained in a safe shutdown condition without the requirement for continuous manning of the control room, onsite backup emergency power service for the control room emergency air cleanup system is no. longer needed to ensure the safety of the facility in its present condition. Conse-quently, an exemption from GDC 17 is also justified. This is based on the fact that the control room emergency air cleanup system is the only remaining load on the emergency diesel generators still required by the facility license; the emergency diesel generators (the onsite electric power system) are not needed to assure core cooling, containment integrity or other safety functions i
at TMI-2 in the current post-accident, cold shutdown condition.
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IV. 6 Accordingly, the Commission has determined that pursuant to 10 CFR 50.12, these exemptions are authorized by law, will not present an undue risk to the public health and safety, and are consistent with the common defense and security.
The Commission further determines that special circumstances, as provided in 10 CFR 50.12(a)(2)(ii), are present justifying the exemptions, namely, that application of the regulations in this particular circumstance is not necessary to achieve the underlying purpose of the rules: to maintain the nuclear power unit in a safe shutdown condition in the event of an accident. Specifically, as noted above, neither continuous control room manning nor operation of an onsite emergency backup power source is necessary to maintain the damaged TMI-2 reactor in a safe shutdown condition. Accordingly, the Commission hereby grants exemption from the requirements of 10 CFR Part 50, Appendix A, General Design Criterion 17 and, in part, from the requirements of General Design Criterion 19.
It is further determined that the exemptions do not authorize a change in effluent types or total amounts nor an increase in power level and will not
( result in any significant environmental impact. In light of this determination and as reflected in the Environmental Asse'ssment and Notice of Finding of No Significant Environmental Impact prepared pursuant to 10 CFR 51.21 and 51.30 through 51.32 (February 9,1987,52FR4067),itisconcludedthattheinstant action is insignificant from the standpoint of environmental impact and an environmental impact statement need not be prepared.
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Theseexemptionsareeffectiveuponissuanceofthecorrespondingcganges to facility Technical Specifications, sections 3.7.4, 3.7.7, 3.7.10, 3.8.1, 3.8.2,3.9.12.1,3.9.12.2,3/4.7.4,3/4.7.7,4.3,4.7.4,4.7.7,4.8.1,4.8.2, 4.9.12.1 and 4.9.12.2.
FOR THE NUCLEAR REGULATORY COMMISSION hd4 !. .. E Frank J. Mraglia, Director Division of PWR Licensing-B Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland this 9th day of February 1987 I
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