ML19309F993
| ML19309F993 | |
| Person / Time | |
|---|---|
| Site: | 05000538 |
| Issue date: | 03/28/1980 |
| From: | Gammill W Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19309F990 | List: |
| References | |
| R-127-A-001, R-127-A-1, NUDOCS 8005020102 | |
| Download: ML19309F993 (12) | |
Text
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- ai UNITED STATES
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fj NUCLEAR REGULATORY COMMISSION r x s; ;;
wasmNGTON, D. C. 20335 MEMPHIS STATE UNIVERSITY DOCKET NO. 50-538 AMENDMENT TO FACILITY OPERATING L_ICENSE Amendment No. 1 License No. R-127 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Memphis State University (the licensee) dated March 23, 1979, as supplemented August 3,1979, and August 28, 1979, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act) and the Commission's rules and regu-lations set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, the pro-visions of the Act, and the rules and regulations of the Commission:
C.
There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) tr.at such activities will be conducted in compliance with the Commistlon's regulations; D.
The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.
2.
Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraphs 2.A 2.B.(2), 2.B.(3), 2.C.(1) and 2.C.(2) of Facility Operating License No.
R-127 a.e hereby revised as Follows:
2.A This license applies to the Model AGN-20lH, Serial No. 108, nuclear research reactor and associated equipment (the facility) owned by Memnhis State University. The facility is located on its campus in Memphis, Tennessee, and described in the licensee's application for construction permit and operating license dated April 11, 1975 and amendments thereto.
2.B.(2) Delete 2.B.(3) Pursuant to the Act and 10 CFR Part 70 "Special Nuclear Material,"
to receive, possess, and use up to 1400 grams of contained uranium 235 enriched equal to or less than 20% in connection with operation of facility, and i
e 2-2.C.(1) Maximum Power Level The licensee is authorized to operate the reactor at steady state power levels not in excess of 20 watts (thermal). Operation at inter-mittsnt power levels not in excess of 1000 watts (thermal) for any seven consecutive day period and not in excess of 3.36 kilowatt-hours is also authorized.
2.C.(2) Technical Specifications The Technical Specifications contained m' Appendix A, as revised through Amendment No. 1, are hereby incorporated in the license. The licensee shall operate the facility in accordance with the Technical Specifications.
3.
This license amendment is effective as of the date of its issuance.
FOR THE NUCLEAR REGULATORY COMMISSION W. P.
- mmill, ting Assistant Director for Operating Reactor Projects Division of Operating Reactors l
Attachment:
Changes to the Technical Specifications Date of Issuance: March 28, 1980 l
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ATTACHMENT TO LICENSE AMENDMENT NO. l_
FACILITY OPERATING LICENSE N0. R-127 D0_CKET NO. 50-538 i
i Replace the following pages of the Appendix "A" Technical Specifications with the enclosed pages. The revised pages are identified by Amendment number and contain vertical lines indicating the area of change.
Pages
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2.0 SAFETY LIMITS AND__ LIM _ITING SAFETY SYSTEM SETTINGS 2.1 S_afety Limits _
Applicability These specifications apply to the maximum core temperature and minimum shield water temperature and level during steady state or transient operation.
Objectiv_e To assure that the integrity of the fuel material is maintained and that essentially all fission fragments are retained in the core matrix.
2.1.1 Sp_eci fi c_a_tio_n The maximum core temperature shall not exceed 200*C during either steady state or transient operation.
Bases _
The polyethylene core material does not melt below 200 C and therefore assures integrity of the core and retention of essentially all fission fragments at temperatures below 200"C.
2.1.2 Specification The reactor shield tank water temperature shall be maintained above 10 C, and the water level in the tank shall not be more than 12 inches below the top of the reactor shield tank.
Bases Low reactor shield tank water temperature may result in freezing of the water. The result of expansion due to freezing of the water may damage the shield tank and other reactor components. This condition would degrade core containment and shielding capability. A safety limit of 10 C provides a margin for confidence that the reactor will not be operated with frozen shield water.
The shield tank water level of 12 inches below the top of the tank j
provides an adequate medium for continuous neutron flux monitoring during reactor operation and ensures adequacy of the facility secon-dary radiation shield for operations greater than 100 milliwatts.
Amendment No. 1 2.2 Limiting Safety System Settings Appl i_cability This specification applies to the parts of the reactor safety system which will limit maximum core temperature.
Obje_ctive To assure that automatic protective action is initiated to prevent a safety limit from being exceeded during steady state or transient opera tion.
Specification The core thermal fuse shall melt when heated to a temperature of 120*C or less resulting in core separation and a reactivity loss of greater than 5% ak.
Bases i
In the event of failure of the reactor to scram, the self-limiting characteristics due to the high negative temperature coefficient, and the melting of the thermal fuse at a temperature below 120 C will assure safe shutdown without exceeding a core temperature of 200 C.
Amendment No. 1 3.0 LIMITING CONDITIONS FOR OPERATION 3.1 R_e_activi ty_ _Limi ts Ap_plicability This specification applies to the reactivity condition of the reactor and the reactivity worths of control rods and experiments.
Objective _
i To assure that the reactor can be shut down at all times and that the safety limits will not be exceeded.
j Specification a.
The available excess reactivity with all control and safety rods fully inserted and including the potential rr. activity worth of all experiments.shall not exceed 0.65% ak/k.
b.
The shutdown margin with the most reactive safety or control rod i
fully inserted shall be at least 2% Ak/k, referenced to 20 C.
c.
The reactivity worth of the control and safety rods shall ensure subcriticality on the withdrawal of the coarse control rod or any one safety rod.
Bases i
The limitations on total core excess reactivity assure reactor periods of sufficient length so that the reactor protection system and/or operator action will be able to shut the reactor down without exceed-ing any safety limits.
The shutdown margin and control and safety rod reactivity limitations assure that +he reactor can be brought and maintained subcritical if the highest reu:tivity rod fails to scram and remains in its most reactive position.
3.2 Control and Safety Systems Applicability These specifications apply to the reactor control and safety systems.
Amendment No. 1 '
I
Objective To specify lowest acceptable level of performance, instrument set points, and the minimum number of operable components for the reactor
^
control and safety systems.
Specification _
l The reactor shall not be made critical unless the following speci-fications are met:
a.
The total scram withdrawal time of the safety rods and coarse control rod shall be less than 200 milliseconds, b.
The maximum reactivity addition rate fnr each rod shall not exceed 0.04% Ak/k/sec.
c.
The safety rods and coarse control rod shall be interlocked such that:
1.
Reactor startup cannot commence unless both safety rods and coarse control rod are fully withdrawn from the core.
2.
Only one safety rod can be inserted at a time.
3.
The coarse control rod cannot be inserted unless both safety rods are fully inserted.
d.
A loss of electric power shall cause the reactor to scram.
The reactor source level measured by the Nuclear Safety Channel e.
No. I countrate instrument is more than 120 CPM.
f.
The reactor core tank is pressurized with dry nitrogen to at least 1 psig.
g.
All reactor safety system instrumentation shall be operable in accordance with Table 3.1 with the following allowable exception:
Nuclear Safety Channel No. 1 may be bypassed provided Nuclear Safety Channel Nos. 2 and 3 are verified to be operable.
I l
l Amendment No. 1 1
TABLE 3.l Safety Channel Set Point Function Nuclear Safety #1
> 12% full scale Scram at source levels j
Low Countrate
<12% of full scale
~
Nuclear Safety #2 (Log)
< 2000 watts Scram at power > 2000 watts High Power Reactor Period
> 5 sec Scram at periods < 5 sec Nuclear Safety #3 (Linear)-
Scram at'*95% of full scale High Power
- 95% full scale Low Power
- 5% full scale Scram at source levels
'5% of full scale I
Shield Water Temperature
> 15 C Scram at temperature < 15 C Shield Water Level
-< 10.5 inches Scram at water levels >10.5 inches below top of shield water tank Seismic Displacement
-< 1/16" Scram at displacements
> 1/16" Core Tank Pressure
< 5 psig Scram at core tank pressure
> 5 psig Scram at operator option Manual Scram Radiation Monitor Alarm at or below level set to meet requirements of 10 CFR Part 20 Alarm at or below level set Air Particulate Monitor to meet requirements of 10 CFR Part 20 Amendment No. 1,
Bases The specifications on scram reactivity rate in conjunction with the safety system instrumentation and set points assure safe reactor shutdown during the most severe foreseeable transients.
The limitations on reactivity addition rates allow only relatively slow increases of reactivity so that ample time will be available for manual or automatic scram durino any operating conditions.
Interlocks on control and safety rods assure an orderly approach to criticality and an adequate shutdown capability.
The minimum reactor source level assures that an adequate neutron countrate from which to conduct an orderly and controlled startup is registered on the startup channel before a reactor startup begins.
Pressurizing the core tank with dry nitrogen to at least 1 psig assures that evolved hydrogen from high power operations cannot agglomerate into hazardous concentrations.
The neutron detector channels (Nuclear Safety Channels #1 througn #3) assure that reactor power levels are adequately monitored during reactor startup and operation. Requirements on minimum neutron levels will prevent reactor startup unless the startup channels (Nuclear Safety Channels #1 and #3) are operable and responding, and will cause a scram in the event of instrumenta-tion failure.
In order to provide assurance that at least two Nuclear Safety Channels are operative for all ranges of reactor operation and to prevent overranging the channel 1 startup instrument, Nuclear Safety Channel #1 is allowed to be bypassed for operations above 40 milliwatts only if the remaining two channels are verified to be operable.
Since the AGN-201 core negative temperature coefficient of reactivity in conjunction with the maximum potential excess reactivity specified in 3.1 prevents reactor operation at high power levels for time intervals necessary to approach established safety limits or limiting safety system settings, the high power level scrams are established to provide redundant automatic pro-tective action at levels low enough to assure safe shutdown during rapid reactivity transients and to prevent exceeding requirements for design of the facility radiation shield. The period scram conservatively limits the rate of rise of reactor power to periods which are manually controllable and will automatically scram the reactor in the event of large reactivity additions.
The AGN-201's negative temperature coefficient of reactivity causes a reac-tivity increase with decreasing core temperature.
The shield water tempera-ture safety channel will prevent reactor operation at temperatures below 15'C thereby limiting potential reactivity additions associated with temperature decreases.
Water in the shield tank is an important component of the reactor shield and l
operation without the water may produce excessive radiation levels and inade-quate neutron flux monitoring capabilities.
The shield tank water level i
safety channel will prevent reactor operation without adequate water levels in the shield tank.
Amendment No. 1 l
The reactor is designed to withstand 0.69 accelerations and 6 cm dis-placements. A seismic instrument causes a reactor scrar,whenever the instrument receives a horizontal acceleration that caures a horizontal displacement of 1/16 inch or greater. The seismic displacement safety channel assures that the reactor will be scrammed and brought-to a suberitical configuration during any seismic disturbance that may cause damage to the reactor or its components.
The manual scram allows the operator to manually shut down the reactor if an unsafe or otherwise abnormal condition occurs that does not other-wise scram the reactor. A loss of electrical power de-energizes the safety and coarse control rod holding magnets causing a reactor scram thus assuring safe and immediate shutdown in case of a power outage.
A radiation monitor must always be available to operating personnel to provide an indication of any abnormally high radiation levels and an air particulate monitor must be available to warn operating personnel of a degradation in core tank or. gas monitoring system integrity so that appro-priate action can be taken to shut the reactor down and assess the hazards to personnel.
3.3 Limitations on Experiments Applicabi?ity This specification applies to experiments installed in the reactor and its experimental facilities.
Objective To prevent damage to the reactor or excessive release of radioactive materials in the event of an experimental failure.
Specification a.
Experiments containing materials corrosive to reactor components or which contain liquid or gaseous, fissionable materials shall be double encapsulated.
b.
Explosive materials shall not be inserted into experimental facilities of the reactor.
The radioactive material content, including fission products of any experi-c.
ment shall be limited so that the complete release of all gaseous, parti-culate, or volatile components from the experiment will not result in doses in excess of 10% of the equivalent annual doses stated in 10 CFR Part 20 l
for persons occupying (1) unrestricted areas continuously for two hours 1
l starting at time of release or (2) restricted areas during the length of l
time required to evacuate the restricted area.
I d.
The radioactive material content, including fission products of any doubly encapsulated experiment shall be limited so that the complete release of l
all gaseous, particulate, or volatile components of the experiment shall Amendment No. 1 i
not result in exposures in excess of 0.5 Rem whole body or 1.5 Rem thyroid to persons occupying an unrestricted area continuously for a period of two hours starting at the time of release or exposure in excess of 5 Rem whole body or 30 Rem thyroid to persons occupying a restricted area during the length of time required to evacuate the restricted area.
Bases These specifications are intended to reduce the likelihood of damage to reactor components and/or radioactivity releases resulting from an experi-ment failure and to protect operating personnel and the public from excessive radiation doses in the event of an experiment failure.
3.4 Shielding Applicability _
These specifications apply to reactor shielding required 'during reactor operation.
Objective The objective is to protect facility personnel and the public from radiation exposure.
3.4.1 Specification The following shielding requirements shall be fulfilled prior to reactor startup and during reactor operation:
a.
The reactor shield tank shall be filled with water to a height within 10 inches of the highest point on the manhole opening.
b.
The thermal column shall be filled with water or graphite. Access to the reactor building roof area above the reactor shall be restricted during reactor operation.
c.
The facility secondary shield shall be in place with removable shield plugs installed.
3.4.2 Specification Access to the reactor room shall be prohibited, except for radiation surveys, during operations above 20 watts.
Bases The facility shielding in conjunction with designated restricted radiation areas is designed to limit radiation doses to facility personnel and to the public to a level below 10 CFR 20 limits under operating conditions, and to a level below criterion 19, Appendix A,10 CFR 50 recommendations under acci-dent conditions.
Amendment No. 1 E
5.0 DESIGN FEATURES _
5.1 Reactor a.
The reactor core, including control and safety rods, contains approximately 660 grams of U-235 in the form of 20% enriched UO dispersed in approximately 11 kilograms of polyethylene. The1bwer section of the core is supported by an aluminum rod and a thermal fuse. The fuse melts at temperatures below 120 C causing the lower core section to fall away from the upper section reducing reactivity by at least 5% ak/k. Sufficient clearance between core and reflec-tors is provided to ensure free fall of the bottom half of the core l
during the most severe transient.
3 b.
The care is surrounded by a 20 cm thick high density (1.75 gm/cm )
graphite reflector followed by a 10 cm thick lead gamma shield. The core and part of the graphite reflector are sealed in a fluid-tight aluminum core tank designed to contain any fission gases that might leak from the core. A valved gas handling system is permanently con-nected to the core tank assembly to permit monitoring and disposal of gases which may accumulate in the tank from high power operations.
c.
The core, reflector, and lead shielding are enclosed in and supported by a fluid-tight steel reactor tank. An upper or " thermal column tank" may serve.as a shield tank when filled with water or a thermal column when filled with graphite.
d.
The 61/2 foot diameter, fluid-tight shield tank is filled with water constituting a 55 cm thick fast neutron shield. The fast neutron shield is formed by filling the tank with 1000 gallons of water. A 44 inch thick concrete block shield supporting a top cover that con-tains approximately 18 inch thick borated paraffin encloses the 61/2 foot diameter shield tank to provide a secondary neutron and gamma i
shield for operations above 100 milliwatts. The complete reactar shield shall limit doses to operating personnel in restricted and unrestricted areas to levels less than permitted in 10 CFR 20 under operating conditions.
e.
Two safety rods and one control rod (identical in size) contain up to 20 grams of U-235 each in the same form as the core material. These rods are lifted into the core by electromagnets, driven by reversible DC motors through lead screw assemblies. De-energizing the magnets causes a spring-driven, gravity-assisted scram. The fourth rod or fine control rod (approximately one-half the diameter of the other rods) is driven directly by a lead screw.
This rod may contain fueled or unfueled polyethylene.
5.2 Fuel Storane_
Fuel, including fueled experiments and fuel devices, not in the reactor shall be stored in locked rooms in the reactor building. The storage array shall be such that K is no greater than 0.8 for all conditions of moder-eff ation and reflection Amendment No. 1