ML20154L087

Discusses Util Ltr of Complaint Re Theory Section of 851119 Written Exam.Theory Section Considered Prototypic

ML20154L087
Person / Time
Site:	Davis Besse
Issue date:	02/18/1986
From:	Defferding L, Huenefeld J Battelle Memorial Institute, PACIFIC NORTHWEST NATION
To:	Maines R Office of Nuclear Reactor Regulation
Shared Package
ML20154J984	List: ML20154L072 ML20154L087
References
NUDOCS 8603110389
Download: ML20154L087 (8)

Text

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OBaHelle Pacific Northwest Laboratories P.O. Box 999 Richland, Washington U.S.A. 99352 Telephone (509) 375-2068 Telex 15-2874 February 18, 1986 Mr. Ron Maines Operator Licensing Branch Division of Human Factors Technology U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Ron:

I am, of course, concerned and dismayed by the letter of complaint that you received f rom Toledo Edison's Davis Besse regarding the theory section (SR0 section 5) that was administered to their candidates on the last written examination given on November 19, 1985. I have reviewed section 5 of that examination, and I feel adamant that it was appropriate. In fact, I consider this type of a theory section to be prototypic. I would welcome the opportunity to defend any or all of the questions contained in that

,. section.

Sincere'ly, Concurrence 'c .. '

J. C. Huenefeld Leo'J . D#f f erding' Power Generation Engineering Program Manager

/c xc: B Boger J McMillen i

f

~. . . ,

,n L Page 1 Davis Besse 1 November 19, 1985 -

Points Available 5.0 THEORY OF NUCLEAR POWER PLANT OPERATION. FLUIDS. (25.0)

AND THERMODYNAMICS 00ESTION 5.01

a. Define shutdown margin. Include any assumptions about axial power shaping rod or control rod positioning. -

(2.0)

b. During a plant heatup in accordance with the Plant Startup Procedure, PP 1102.02, the reactor must be shutdown by 11% Ak/k. If Group 1 rods are withdrawn, does their worth count as part of that 1% Ak/k? (1.0)

OUESTION 5.02

'While drawing a bubb5e"in the pressurizer, the vapor space

~

is vented to the quench tank. Describe how conditions in the quench tank can be used for determining when a steam bubble exists in the pressurizer. (2.0) .

00ESTION 5.03 During a reactor plant startup with three reactor coolant pumps .

running, will Quadrant Power Tilt (QPT) be more limiting at .

low power or high power? Exclain. (2.0) i

-Section 5 Continued on Next Page- .

. I

3~

,b Page 2 -

Davis'Besse 1 November 19, 1985 .

Points Available OUESTION 5.04 Curve "A" on the trace.below is a logarithmic plot of total neutron power versus time after a reactor trip. Curve "B" is

, a plot of the neutron power due to delayed neutrons alone versus time for the same trip. Exolain why total neutron power (i.e.,

curve A) does not drop all the way down to the delayed neutron level (1'.e., to curve B). / (2.0)

A - TOTAL NEUTRON .

PONER 9 a - ett m n ) ' __,~~~

c pCutn0Ns __ ,_

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.__~~

U ~

~~~

N .

3 P.

A. .

T E

IlilE 00ESTION 5.05 The reactor is critical at 10 -8 amps. A stable 1 DPM startup rate is achieved. If rods are inserted continuously until startup rate drops to zero, and then the rod insertion is immediately stopped, EL11 the reactor be critical, supercritical, or. sub-cri tical? Exclain. (2.0)

-Section 5 Continued on Next Page- .

I 1

e a

,s Page 3 .

. Davis Besse 1 November 19, 1985-Points Available OUESTION 5.06 The figure below shows neutron population response to reactivity insertion. Label each of the three (3) curves as supercritical, exactly critical, or subcritical. (Assume below the point of feed-backeffects.) (1.0)

A B .

c.

N,' ""~~ ~ ~ ~ ~ - ~}~ ~~~~~

,l b

NIutron -

' hpulation N, ~ __

• N% s --

N- 3

--g I N/ ii !

II II ! '

/IN tnic 113 seconds  ;

At, gg, Al s

-Section 5 Continued on Next Page- ,

Page 4 -

Davis Besse 1 November 19, 1985 .

Points Available OUESTION 5.07 Given a large vented tank 30 ft. in diameter and 60 ft. high with a centrifugal pump taking a suction from its base. The pump is located at a vertical elevation corresponding to the

'bottomofthetagk. The tank is entirely full of water and is maintained at 60 F by heaters. Assume the vent becomes totally clogged while the pump is in operation. Atmospheri,c pressure is 14.7 psia. Answer the following questions:

a. What is the maximum differential pressure that could occur

.between the inside and outside of the tank? Exclain. (1.5)

b. Exclain why the pump may begin to cavitate at a higher .

tank level than with the vent open. -

(1.0)

QUESTION 5.08

When conducting a rapid plant shutdown at 25 MW per minute (Abnormal Procedure AB 1203.07), why is the operator required .

to add boric acid to the makeup tank as unit load decreases? (2.0)

OUESTION 5.'09 Assume that the condenser is not available and the operator is manually controlling steam generator pressure at 995 psig using ethe atmospheric vent valves. Estimatehowmanygglionsof

. water would be required to cooldown the RCS from 582 F to 546 F.

Shan assumptions. (2.0)

a. 350 gallons

b. 3500 gallons .

c. 35,000 gallons

d. 73,000 gallons

-Section 5 Continued on Next Page- .

h

,o Page 5 '

Davis Besse 1 November 19, 1985 -

Points Available 00ESTION 5.10 Consider the ' system shown below (an 80 "ft high loop of

'3 ft diameter steel pipe and a gressurizer). Initially the pregsurizer is saturated at 640 F and the loop is subcooled at 546 F. Assume that the entire system, including the pressurizer is allowed system due cooldown. The thermal to this cooldown conft3raction is 600 . Will the of pressurizer the entire be empty? Exclain. (1.5)

_c_

o- y e.

l00* , T"3" f 4  % Si .

-Section 5 Continued on Next Page- .

I

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• Page 6 .* Davis Besse 1 November 19, 1985 .

Points available, OUESTION 5.11 The reactor is at 100% FP equilibrium xenon conditions when a reactor trip occurs. Three (3) hours later the reactor is restarted. -

8

a. , When at:.107 amps, which direction will rods have to go

, to hold power constant? Exclain. (1.0)

~

b. Sketch tIhe xenon concentration through to equilibrium assuming the reactor is raised to 92% power within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> .(<4 hours a.fter the , trip). ._ (1.5)

'8- 00ESTION 5:12 When borating from a lower to a higher boron concentration, Ehy will the final boron conce,ntration value always be 3 to 4%

lower than anticipated?

(1.0)

QUESTION 5.13 Why are SFRCS tripped and AFW actuated immediately following a loss of NNI X DC power, rather than waiting for the plant transient to initiate an SFRCS actuation? (1.5) -

-End Section 5-9 8

9' I

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