ML19305E478

Repsonds to Questions 3,4,6,7 & 13 Per Div of Reactor Licensing Request Re Proposed Amend to Operate at 5 Mw. Existing Cooling Tower for Secondary Water Is two-cell Unit. Collection Basin & Pump Suction Well Common to Both Units

ML19305E478
Person / Time
Site:	Neely Research Reactor
Issue date:	07/13/1971
From:	Kirkland R Neely Research Reactor, ATLANTA, GA
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML19305E473	List: ML19305E476 ML19305E478
References
NUDOCS 8005120505
Download: ML19305E478 (6)

Text

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• Aslents, Geerple 303J2 July 13, 1971 U. S. Atomic Energy Commission Division of Reactor Licensing Washington, D. C. 20545 Ref. Dockst 50-160 Gentiemen:

his letter is a partial response to a number of questions from the DILL staff requesting additional information on our proposed ammendment to operate at 5 Mw. Specifically, we are responding to questions Nos. 3, 4, 6, 7, and 13.

Responses to the remaining questions are currently being developed.

Question 3.

" Describe and evaluate the primary D20 system's operational capabilities when the reduced flow standby pump is on line. Include the following:

"a. How the standby pump is brought on line.

"b. Effects of the reduced flow on power, flow, reactivity, secondary systems and safety interlock system' settings.

"c. Effects of the secondary H2O system standby pump on tha primary system's operational capabilities when on line.

"d. Effects of the reduced flow secondary

• HO 2 standby pump on the secondary system."

_ Response Circulation of the D 20 in the primary system will normally be provided by a centrifugal map that will deliver 1000 gallons per minute with a total head of 130 feet., A second, standby pump, is also installed in the D 20 circulating system. h is smaller capacity pump is expected to deliver

! approximately 1200 gallons rer minute flow. S e purpose of the standby ptmp is to provide backup capability for the main pump, here is, however, no need for rapid startup of the standby purg. Should a failure of the main circulating pump occur, an administrative decision would be made as to the desirability of resoval and repair of the failed unit or operation of the reactor at a reduced power. ghould reduced power operation appear desirable, it would then be necessary to change the safety system interlock settings on the Power Trip and 14w D20 Flow circuits. Se values for the trip settings will be those specified in the Technical Specifications (not developed at this -

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U. S. Atomic Energy Constission July 13, 1971 Circulation of the H O 2 in the secondary system will be provided in a manner very similar to the one described above for the D 0 2 system.

The main H 2O pump will provide a flow of 1200 gs11ons per minute through the shell side of the heat exchangers. There will be a standby pump which is expected to deliver approximately 1000 gallons per minute flow. Again, there is no need 1.or rapid startup of this standby ptunp. The decision to use it will be an administrative one. Should this reduced flow pump be placed in service, the low H2 O Flow safety circuit would be reset. Resetting of the reactor power and 2D 0 temperature and flow interlocks will not be required. The limitation imposed by the secondary system on the primary system is one of heat removal capacity.

H e design of the secondary system was based upon conditions that do not frequently occur, i.e., very high wet and dry bulb temperatures of the air ucer the cooling towers. It is therefore quite likely that operation of the secondary system at reduced flow would, of itself, impose no limitation upon the reactor power or D2 0 circulating system. Should the need arise for reduced secondary flail concurrent with adverse weather conditions, it would require operation of the reactor at a somewhat reduced power to maintain the D2 0 temperatures within the limitations proscribed in the Technical Specifications.

Question 4.

"De' scribe the operational limitations placed on the primary and secondary systems when one of the cooling towers becomes inoperable."

Response

The existing cooling tower for the secondary water is a two-cell unit. Each of the units has its own induced draf t fan and water distribution system.

The collection basin, pump suction well, and tower bypass valve are common to both units. Each of the cells is capable of handling 600 gallons per minute; the bypass valve can handle the entire secondary system flow of 1200 gallons per minute. Should a failure occur in one of the cells, the water to that cell would be isolated if required. Secondary flow would then be split between the other cell and the tower bypass loop. Under these conditions it is very likely that the secondary system would be unable to 4

! remove the heat in the primary system from operation of the reactor at 5 Hw.

The reactor would therefore be operated at some reduced power that was within the heat removal capacity of the secondary system and consistent with the D20 temperature limitation as specified in the Technical Specifica-tions.

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Question 6.

" Indicate what criteria will be used to determine the following:

"a. Wether amargency* cooling is required following an electrical power failure.

"b. Wether long-term city water is required during emergency cooling."

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Response

The criteria for the D 02 emergency coolant system is to supply 8 gal / min of D2 0 for 30 minuta to the reactor core, his requires 240 gallons of u2 0 h e actual storert tank will have a capacity of 300 gallons. Therefore, in the event of a power failure which initiates the addition of emergency D20 coolant to tha core, there is approximately seven minutes for the reactor operator to determine whether or not the emergency coolant is actually required, i.e., that an actual loss of coolant from the reactor has occurred simultaneously with the power failure. Tht operator's first action will be to observe the pneumatic reactor tank level indicator for any observed drop in level (battery-powared, emergency lighting is available). The reactor operator or his designate will then proceed to the reactor tank sight glass insertanent located on the main floor. If there is any indication of a dropping reactor tank level, an entry will be made into the process equipment areas. .

In the manner outlined above, the reactor operator will determine whether emergency coolant is required. If coolant is not needed, he will close the manual block valve in the D 20 emergency coolant supply line.

The purpose of the 300-gallon emergency cociant tank is to have an inanediately supply of water available to use in the unlikely event of a loss of coolant from the reactor core. D2 0 is put into the tank so that periodic operational checks can be made of the system without degradation of the primary coolant

D2 0.

Once it has been determined that emergency cooling is required, i.e., s loss of coolant condition exists, then city water (H O)2 will be required as soon as the 300 gallons of D2 0 is ex$austed. Le 30-minute time between initiation I of D2 0 to the core and its exhaustion will provide sufficient time to install a quick-connect jumper into the H2O supply line to the ECS system from the building city water supply.

Question 7

" Describe.the. safety precautions or safety interlock circuit which ensures that the normally locked-open manual stop valve in the emergency cooling line has been reopened following an electrical power failure or is reopened in the event that emergency coolant is subsequently required."

_ Response Following a power failure, the reactor operator will determine ether emergency cooling to the core is required. If not, i.e., no loss of coolant has occurred,

. he will unlock and close the manual stop valva to conserve the D 20 in the ECS tank. Unlocking the valve will open an interlock in the permissivs startup circuitry. his will prevent a subsequent startup with the valve in the closed position.

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O U. S. Atomic Energy Commission July 13, 1971 During the time when no electrical power is availab}a, it will be necessary  !

for the status of the reactor tank to be monitared by a reactor operator to ascertain if there is a need for emergency coolbig. Assurance of this monitoring requirement vill be accomplished by administrative procedure.  !

It will be necessary for the monitoring to continue up to eight hours follow- l ing chutdown of the reactor. This operator surveillance is similsr to that  :

required following a normal reactor shutdoun, except that no electrical power is available. Adequate emergency lighting is available. The level of D 0 in i

2 the reactor tank will be monitored by a passive sight glass instrument located on the main floor of the containment building. Additionally, access to the process equipment area will permit monitoring of the D2 0 piping system. Any -

significant D20 loss would collect in this area of the building.

Sueation 13. .

" Describe how it is assured during reactor operation that at least 300 gallons of coolant is in the emergency coolant tank. Indicate how valve or pipe leaks are detected. Include alarms and/or interlocks that exist."

Resoonse l The criteria for the emergency coolant tank volume is to provide a supply of D2 0 at a rate of eight gallons per minute for 30 minutes. This requires 240 gallons of D20; the actual tanh volume is approximately 300 gallons at i overflow. The water level in the tank will be monitored by a DP cell having a low-level detection circuit. Actuation of the low-level circuic at a level equivalent to approximately 230 gallons will warn the reactor operator that the D2 0 is not at overflow. This

• tme circuit vill actuate an interlock in the reactor permission startup ci cuitry,to assure that the reactor is not started up with less than 200 gallons of D2 0 in the tank.

The majority of the piping in the emergency coolant system will be of welded construction. This and the mild temperature and pressure conditions occur-ring in the system should minimize D20 leakage. Those points from which leakage might be expected, i. e., valve packings and flanges vill be monitored by a conductance type leak detection system connected to the presently installed D 3 2 Leak Detection system. There is an existing alarm on the Control Room annunciator panel to warn the reactor operator of a D2 0 leak.

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U. S. Atomic Energy Commission July 13, 1971 !

Please advise me if you should require additional information on any of the above questions or responses. Thank you for your consideration and patience in this matter.

Sincerely yours, A

R. S. Kirkland, eactor Supervisor

. Nuclear & Biological Sciences Division No ry, h

t.;c. Georgia, State at Large My con m? mon Eeires July 13,197J Notary Public cc: Nuclear Safeguards Commaittee Dr. G. W. Leddicotta

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GTRR REF. NO:

s [ GEORGIA TECII RESEARCII REACTOR 900 Atl:ntic I) rive, N. W.

Atlanta, Georgia 30318

• " REQUEST FOR MINOR EXPERIMENT APPROVAL y, REQUESTING

1. ORGANIZATION:

ADDRESS:

DME: NAME OF CONTACT. TELEPHONE NO:

MATERIAL TO BE IRRADIATED: (DIMENSIONS AND WElGHT, INCLUDING WEIGHT PERCENTAGES OR ELEMENTS IN ALLOYS AND COMPOUNDS):

DESIRED 1RRADIATION LOCATION OR FLUX:

DESIRED IRRADIATION TIME:

ITEMlZE ESTIMATED ACTIVITIES OF PRINCIPAL ISOTOPES: (ATTACH COPY OF CALCULATIONS):

ISOTOPE ACTIVITY l lSOTOPE ACTIVITY DESCRIPTION OF SAMPLE CONTAINER:

PREFERRED RETURN SHIPP!NG METHOD: PURCHASE ORDER NO:

LICENSE (ISSUING AGENCY AND LICENSE NUMBER):

(ENCLOSE A COPY OF THE LICENSE UNDER WHICH POSSES $10N OF THE ABOVE ISOTOPE IS AUTHORIZED.)

SIGNATURE TITLE FOR GEORGIA TECH USE ONLYr ACCOUNT NUMBER:

IRRADIATION CONTAINER:

IRRADIATION HOLDER:

SPECIAL INSTRUCTIONS:

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l APPROVALS: l 1

EXPERIMENT COORDINATOR DATE BUSINESS OFFICE: DATE 1

REACTOR SUPERVISOR l DATE O.R.S. DATE mum OFFICE OF R ADIOLOGICAL S AFETY

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