ML19246A943

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Safety Evaluation Supporting Amend 3 to License R-125
ML19246A943
Person / Time
Site: University of Lowell
Issue date: 05/29/1979
From:
Office of Nuclear Reactor Regulation
To:
Shared Package
ML19246A939 List:
References
SER-790529, NUDOCS 7907100027
Download: ML19246A943 (4)


Text

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LNITED STATES

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.1 NUCLEAR REGULATCRY CcMMisSION

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SfFETYEVALUATICN3YTHECFFICECFNUCLEARREACTCRREGULATION SUPCORTING AT' ENC"ENT NO. 3 TO LICENSE NO. R-125 UNIVERSITY CF LCWELL CCCKET NO. 50-223 INTpCDUCTICM Sy letter dated March 16, 1979, the University of Lcwell (the licensee) requested a change to the Technical Scecifications for the University of Lcwell Reacter (CLR) c0ncerning the frecuency of conducting the ccntainment integrated leak rate test.

DISCUSSION The ULR is a light-water cooled and mcderated pool reactor cf the MTR type authorized to cperate uc to 1 megawatt (themal) pcuer. The fuel elements are in the form of boxes ccntaining flat fuel plates of aluminum-uranium alloy clad with aluminum. Control of the reactcr is provided by four safety blades and a regulating red which use baron carcide as the neutrcn poiscn material. The four safety blades subdivide the core into three sections. The ecdules surrounding the fuel array may be utilized f or graphite reflectors cr radiation baskets and must be filled with oneor the other to ensure proper ficw distribution with forced circulation. In addition, fuel elements in the interior of the core array may be reclaced with radiation baskets. Since replacing a fuel element with a radiation basket changes the neutron flux distribution, flux measurements are required to msure prccer conditicns exist before proceeding to higner pcwer levels.

The core structure is lccated in a 31-fect deep ; col wnere it is suscended frca a movable bridge allcwing it to be positioned at varicus locations adjacent to several experimental f acilities.

Connections to the primary coolant system are provided at two different bridge locations so that tne reacter can be ccerated in the forced circulation Ocde (necessary for power levels above 0.1 "W) at either place.

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2 Cooling for the reactor at pcwer levels above 0.UN is provided by the primary c:alant system which, when piping connections are established between the pipes in the pcol walls and the movable bridge, pumes water through the core to a 2CCO gallen hcIdup tank (for decay of short-lived water activaticn isotopes), to the pump, a heat exchanger, and back to the core.

Cooling is supplied to the core by a 10-inch aluminum pipe connected to the inlet ficw channel box forming one side of the sus:ension frame. Cooling water is then directed from this plenum laterally to the t0p of the core where the CO0lant turns and ficws dcwnward through the care. Frcm there, the c:alant enters an outlet ficw or riser channel box and finally a 10-inch diameter pipe which is connected to the primary ccolant pump suction via the holdup tank.

The facility radiation monitoring system includes continuous air and area radiaticn monitcrs at various. locations within the reactcr building. In addition, a monitor located in the building ventilation stack monitors gasecus and particulate activity. Each radiation mcnitor can provide an alarm en detecticn of high radiation levels permitting emergency procedures to be put into effect to minimi:e radiation expcsure of personnel.

The reactcr building is in the form of a steel containment shell lined with concrete. The building is provided with two access airlocks and these and other penetrations are designed to maintain air leakage frcm the building to less than IC*.' of the building volume per day with a building overpressure of 2 psi. Building air is ner ally filtered and exhausted through a 100 foot stack adjacent to the,

building. In the event of a release of radicactivity within the building, the normal ventilation system will be isolated and the building air will be exhausted through a filter system at a sicw rate, sufficient to maintain a negative air pressure within the building.

Evaluation The University of Lowell Reactor is similar in characteristics to several other research reacters that have ccerated satisfact rily at pcwer levels uo to five megawatts (ther al) and whose coerating experience provides confidence in the predicted behavice of the ULR.

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. Centainment leak rate was originallyspecified to be 0.1% of the building volume per day at 2 psig overpressure. The building 1s originally constructed was tested and determined to meet this value. Hcwever, because of varicus penetrations, it was concluded that the design leak rate could nct be. met. As a result, an analysis was provided by the licensee that a value of IC%

per day would be a satisfactory rate. The NRC evaluation (see original safety evaluation dated 12/24n4) and testing of tne containment shcwed that the actual leak rate was less than half the IC% per day value and that the calculations in the licensee's Safety Analysis were conservative. This evaluation also concluded from evaluation of several accident analyses that the routine producticn of radicactive wastes would present no sub-stantial hazard to the puolic.

Containment integrated leak rate test results since commencement of operation Cecemoer 24,19'4, have substantiated that the actual leak rate has been less than IC% of the building volume per day at 2 psig overpres are, Actual rates have been less than 25P of the 10% specified in the Technical Specifications.

The licer.see has requested that Technical Specificaticn 4.4.3 be changed so that the integrated leak rate of the containment build-ing shall be perfor ed at intervals of 24 months (+ 4 months) instead of 12 months (+ 2 mcnths) presently requirid.

TPe type test conducted by the li ensee it s milar to a type A test as described by Acpendix J to 10 CFR part 30 for pcwer plants.

Type A tests for pcwer reactors are required in sets of three erfor ed at accroximately eaual intervals during each 10-year period. This schedule was estaolished because of the requirement to conduct Type 3 and C tests. Acpendix J requirement are not acclicable to research reactors.

Changing the Technical Scecification requirement to ccnduct t1e tests at intervals of 24 months is consistent with Accendix J frecuency and therefore would provide the ULR a sufficient surveillince frequency to ensure early detection of any major leaks in t!.a containment.

ENVIRCNMENTAL CCNSICERATICN de have determinec tnat the amencrent dces not authcrire a chance in effluent ty;es or total amounts ncr an increase in Ocwer 'evel inc will not result in any sicnificant environmental imoact. Having made this determination, we nave further c:ncluded that the amencment involves in action unich is insi:nificant fr:m tne stancocint cf environmental i: cact and, cursuant to 10 CFR 551.5(d)(4), that in environmental i Dact statement er negative declaration ind environmental imcact accrais need not be prepared in connection with tne issuance cf this amend.aent.

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Conclusion We have concluded, based on the considerations discussed acove, that:

(1) because the amendment does not involve a significant increase in the prcbability cr consequences of accidents previcusly considered and dces not ir.volve a significant cecrease in a safety margin, the amendment dces not involve a significant hazards considerat'on, (2) there is reasonable assurance that the nealth and safety of the public will not be endangered by cceration in the proposed manner, and (3) such activities will be concucted in compliance with the Ccmmissicn's regulations and the issuance of this amendment will not be inimical to the ccamen defense and security or tc the health and safety of the public.

Dated: May 29,1979 S

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