ML19341C515
| ML19341C515 | |
| Person / Time | |
|---|---|
| Site: | 05000192 |
| Issue date: | 01/31/1981 |
| From: | TEXAS, UNIV. OF, AUSTIN, TX |
| To: | |
| References | |
| NUDOCS 8103030675 | |
| Download: ML19341C515 (5) | |
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1.
INTRODUCTION AND
SUMMARY
This report describes the reactor facility and provides a safety evaluation which shows that the TRIGA* Mark I reactor poses no health and safety problems to the public.
1.1.
PRINCIPAL DESIGN CRITERIA The reactor will be operated in two modes: steady-state and pulsing.
Reactor power levels in the steady-state mode will range up to and r-
'ude 250 kW.
Pulsed mode operat ~on will take pir.ct by step reactivity insertions with the reactor initially at a power level less than 1 kW.
The maximum step reactivitv insertion will be 1.5% 6k/k ($2.15).'hich will produce a peak rcar tsi-power of approximately 250 MW(t).** A summary of principal design parameters for the reactor is given in Table 1-1.
1.2.
DESIGN HIG!!LICIITS The reactor will be located in a reactor pool structure. Reactor cooling will be provided by natural circulation of pool water which is in turn cooled '
and purified in external coolant circuits. Reactor experiment facilities will include rotary specimen rack, pneumatic transfer system, in-core irradiation positione and vertical beam tubes.
- Trademark registered in U.S. Patent Office
- This value and others used in this report represent the latest design parameters, or maximum values as a means of evaluating the safety of the
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system. For this reason, these values may dif fer from those quoted in other documents or from those that will be measured in the operating reactor system.
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1 TABLE 1-1 PRINCIPAL DESIGN PARAMETERS Reactor type TRIGA Mark I Maximum steady-state power level 250 kW Maximum pulse 1.5% 6k/k ($2.15)
Fuel element design Fuel-moderator material l'-ZrH 1.6 Uranium content 8.5 wt %
Uranium enrichment 20% U-235 Shape Cylindrical Length of fuel 38 cm (15 in.) overall Diameter of fuel 3.63 cm (1.43 in.) o.d.
Cladding material Type 304 stainless steel Cladding thickness 0.051 cm (0.020 in.)
Number of fuel elements 463 (minimum core) j Excess reactivity, maximum 2.25% Sk/k (cold, clean)
Number of control rods 1
Safety-transient 1
Regulating 1
Shim 1
Total reactivity worth of rods 5.1% 6k/k Reactor cooling Natural convection of pool water
(*}The nominal H/Zr ratio is 1.60, and the maximum value is 1.65.
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The inherent safety of this TRIGA reactor has been demonstrated by the extensive experience
- acquired from similar TRIGA systems throughout the world. This safety arises from the large prompt negative temperature coeffi-cient that is characteristic of uranium-zirconium hydride fuel-moderator ele-i monts used in TRIGA systems. As the fuel temperature increases this coeffi-cient immediately compensates for reactivity insertions. The result is that the reactor power excursions are terminated quickly and safely, i
The prompt shutdown mechanism has been demonstrated extensively in many thousands of transient tests performed on two prototype TRIGA reactors at the General Atomic laboratory in San Diego, California, as well as in the 30 cther pulsing TRIGA reactors in operation. These tests ine19ded step reac;ivity insertions as large as 3.5% 6k/k with resulting peak reactor powers up to 8400 MW(t) on TRIGA cores containing similar fuci elements as are used in this TRIGA reactor.
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Because the reactor fuel is similar, the previously cited experience and tests apply to this TRIGA system. As a result it has been possible to use accepted safety analysis techniques applied to other TRIGA facilities to update evaluations with regard to the characteristics of this facility.
(Ref. 1-5).
1.3.
CONCLUSIONS Past experience has shown that TRIGA systems can be designed, constructed, end safely operated in the steady-state and pulsing modes of operation. This history of safety and the conservative design of the reactor have permitted TRIGA systems to br. sited in urban areas using buildings without pressure-type containment such as is normally associated with reactors of like power levels.
- Forty-eight TRIGA reactors are now in operation throughout the world and of these 31 are pulsing. TRIGA reactors have more than 450 reactor years of operating experience, over 30,000 pulses, und more than 15,000 fuel element years of operation.
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i Results of this safety analysis indicate that the TRIGA Mark I reactor
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system proposed for construction and operation will pose no health or safety problem to the public when operated in either normal or abnormal conditions.
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Abnormal or accident conditions considered in this analysis include:
1.
Complete and instantaneous loss of reactor pool water i
2.
A step insertion of the total excess reactivity available in the 4
core (2.25% 6k/k) with the reactor operating at a low steady-state
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power, i.e., less than 1 kW (t)*
i In both these postulated conditions, fuel and clad temperatures remain at levels below those required to generate stress conditions which would
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cause loss of clad integrity. However, the results of a clad failure are I
analyzed and it is shown that such a failure will not cause excessive radia-tion exposures.
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The loss of pool water has been examined from the standpoint of direct radiation exposure to operating personnel as well as in terms of maintaining l
fuel integrity.
l The effects of argon-41 and nitrogen-16 production during normal opera-tion of the reactor have also been evaluated. Results of these analyses j
show that production of these radioactive gases will present no hazard to persons in the reactor room or to the general public.
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- This analysis is included simply for completeness.
It is recognized j
that this is also a normal operating mode.
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Chapter 1 References 1.
"llazards Report for TRIGA Mark II Pulsing Reactor," General Atomic Division Report GA-1998, February 1961.
2.
"flazards Summary Report for a TRICA-I Nuclear Reactor," University of Texas Bureau of Engineering Research, October 1961.
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3.
" Safeguards Analysis Report for TRIGA Reactors using Aluminum-Clad
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Fuel," General Atomic Division Report GA-7860, March 1967.
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4.
" Safety Analysis Report for 250 Kilowatt Operation of a TRIGA Mark I j
Nuclear Reactor," University of Texas, College of Engineering 4
August 1967.
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" Safety Analysis Report for the TRIGA Mark Il Reactor," E-117-478, 4
October 1975.
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