ML19332F389

Proposed Tech Specs Re Reactor Vessel pressure-temp Limitations & Pressure & Temp Limitations for RCS

ML19332F389
Person / Time
Site:	Vermont Yankee
Issue date:	11/10/1989
From:	VERMONT YANKEE NUCLEAR POWER CORP.
To:
Shared Package
ML19332F331	List: ML19332F330 ML19332F389
References
NUDOCS 8912140364
Download: ML19332F389 (2)

Text

__ -- --

y

=c.

n. ..

17, Fi ure 3.6.i '

~

A ReactorVessel , -

eo Pressure-Temperature Limitations

'[q Valid Thru 4.46E8 WH(t) (32 EFP()

"o Curves are in accordance Ylith A usted Reference Imperoivre 01 4T = Bff 10CFR50 Ap*o 0 and RG 1.99 Rev 2 u

A usted Reference Taperoture 01 4T = 737 i 5 -

sN A usted Reference Imperature et flonge = 207 .

• ~_ 1200- -

s - .  : '

~

N7) Leak Test fUpperLimitm 1000 --

• "d "Yd' y -

1. f0

[ar/ne e -

C' - '

^ .

a 800 - - - - --

i ' ~

/

ww

~~

600 -

$3m - - - - - - - -

/

8$ Normal r Limit M u= 400 =- operation Suberitical- 1 r%Mr

-- - - - - - - - - - - --- \ - -- - - - . -

u

\ -

r Limit Normal operation

" 200*

'---- 100 F/hr Critical r--- - - - - - - - - - -

Start of i -- - - - - - - - -

l - -

Pressurized Region *g Permissible -

3 ' I Criticality I

0 1 . . +

1 Region

+

60 B0 100 llo 12 0 14l0 150 1$0 200 220 24'O 260 280 300 REACTOR C001. ANT IEMPERATURE - 0F Amendments no. 52, BX, 95 111

=:

( +

a 4

VYNp3 '

Beses e

3.6 and 4.6 . Reactor Coolant Systes A. Pressure and Temperature Limitations All components in the Reactor Coolant System are designed to withstand the effects of cyclic loede due to system ,

temperature and pressure changes. These cyclic loeds are introduced by normal leed transients, reacter trips, and startup and shutdown operations. The various categories of toed cycles used for design yarposes aro provided in Section 4.2 of the FSAR. During startup and shutdown, the rates of temperature and pressure changes are lietted so that the maximum specified heetup and cooldoun rates are consistent =ith the design assusptions and satisfy the stress limits for cyclic operation.

• During heatup, the therwel gradients in the reactor vessel wall produce thermal stresses which very free compressive et the inner well to tensite at the outer well. These thermal induced cogresolve stresses tend to alleviate the tensile stresses induced by their internal pressure. Therefore, e pressure-teeperature curve based on steady-state conditions (i.e., no thermal stresses) represents a lower bound of eli stallar curves for t finite heetup rates den the inner well of the vessel is treeted as the governing locatione.

The heetup onetysis also covers the determination of pressure-temperature limitettene for the case in which the outer well of the vessel becomes the controlling location. The thermal gradients established during heetup Produce tensile stresses et the outer well of the vessel. These stresses are additive to the pressure induced tensile stresses which are already present. The theres1 induced stresses at the outer mall of the vessel are tensile and are dependent on both the rate of heetup and the time along the heetup re g ; therefero, a louer bound curve sieller to that described for the heetup of the inner mell cannot be defined. Subsequently, for the cases in which the outer well of the vessel becomes the stress controlling location, each heetup rete of interest must be analyzed on an individual basis.

. r In order to prevent undue stress on the vessel nossles and bottom heed region, the recirculation loop temperatures should be within 500 F of each other prior to staetup of an idle loop.

The reactor vessel meterials have been tested to determine their initial reference temperature all-ductility transition toeperature (RTNDT) of 400y nexteus. Reactoc operation and resultant fast neutron (s >l llev) irradietion will cause an increase in the ETsDT. Therefou , an adjusted reference temperature con be predicted using current industry practices and Vermont Yankee Surveillance program data. (Begulatory Guide 1.99, Revision 2, and Battelle Columbur Laboratory Report SCL 585-84-3, dated Ney 15, 1984. The pressure / temperature operation through 4.46 x108 limit curve, Figure 3.6.1, includes predicted adjustments for this shift in RTggy for j sensing instruments. teal (t), as well as adjustments for possible errors in the pressure and t n a ture

- I Amendment No. $E, # , gd, 117

_- __-