ML20236K691

Proposed Tech Specs,Revising pressure-temp Limits for Heatup & Cooldown,Normal Operation & Pressure Testing

ML20236K691
Person / Time
Site:	Cooper
Issue date:	10/28/1987
From:	NEBRASKA PUBLIC POWER DISTRICT
To:
Shared Package
ML20236K655	List: ML20236K691 NLS8700560, Application for Amend to License DPR-46,changing Tech Specs to Revise pressure-temp Limits for Heatup & Cooldown,Normal Operation & Pressure Testing.Fee Paid
References
NUDOCS 8711090312
Download: ML20236K691 (8)

Text

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LIMITING CONDZTIONS FOR OPERATION SURVEILLANCE, REQUIREMENTS 3.6 Primary System Boundary 4.6 Primary System Boundary Applicability: Applicability:

Applies to the operating status of Applies to the periodic examination the reactor coolant system, and testing requirements for the i reactor cooling system.

Objective: Objective:

To assure the integrity and safe op- To determine the condition of the i eration of the reactor ecolant sys- reactor coolant system and the tem. operation of the safety devices related to it.

Specification: Specification:

A. Thermal and Pressuri'.ation Limitations A. Thermal and Pressurization Limitations

1. The average rate of reactor coolant 1. During heatups and cooldowns, the-temperature change during normal heat- following temperatures shall be per-up or cocidown shall not exceed manently logged at least every 15 100*F/hr when averaged over a one- minutes until the difference between hour period, any two readings taken over a 45 minute period is less than 50*F.

a. Bottom head drain.

b. Recirculation loops A and B.  ;

2. During operation where the core is 2. Reactor vessel temperature and reactor critical or during heatup by non- coolant pressure shall be permanently nuclear means or cooldown following logged at least every 15 minutes when-shutdown, the reactor vessel metal ever the shell temperature is below and fluid temperatures shall be at 220*F and the reactor vessel is not or above the temperatures shown vented.

on the limiting curves of Fig-ures 3.6.1.a or 3.6.1.b.

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3. The reactor vessel metal temperatures for the botton head region and >

beltline region shall be at or above 3. Test specimens of the reactor vessel the temperatures shown on the base, weld and heat affected zone metal limiting curves of Figure 3.6.2 subjected to the highest fluence of during inservice hydrostatic or leak greater than 1 Mev neutrons shall be i testing. The Adjusted Reference installed in the reactor vessel adjacent  !

Temperature (ART) for the beltline to the vessel wall at the core midplane {'

region must be determined from the level. The specimens and sample program appropriate beltline curve (8, 10, shall conform to ASTM E 185-73 to or 12 EFPY) depending on the current the degree possible, accumulated number of effective full j power years (EFPY). The ART curve  !

for the bottom head is valid to l 12 EFPY.  !

l 90 yd1090'312 occa hoeoa  ;

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LIMITING CONDITIONS FOR OPERATION  ! SURVEILLANCE REQUIREMENTS'

'3.6.A (cont'd.)- i.6.A (cont'd.). d The schedule'for withdrawal of the remaining two caps'ules'is based on.

ASTM E185-82 and is as.follows:..

Second Capsule r 215: EFPYJ Third Capsule: 12 EFPY' l

l l

l I

d 1

.J 1

i J .

1 J

m i

4

4. The Reactor vessel head bolting 4. When the reactor vessel head bolting j 3

studs shall not be under tension studs are tensioned'and the reactor is' unless the temperaturesof the vessel in a Cold Condition, the. reactor. vessel '

head flange and the head is greater shell' temperature immediately'below l) than 80 F. the: head-flange shall be permanently.

recorded. ,

5. The pump in an idle recirculation loop 5. Prior'to and duEing startup of a'n I shall not be started unless the temp- idle, recirculation loop,'the temperature eratures of the coolant within the of'the reactor coolant in'the operating idle and operating recirculation loops and idle loops.shall be permanently are within 50 F of each other. logged.'  ;

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6. The reactor recirculation pumps shall 6' . Prior to - starting .a recirculation pump,,

not be started unless the coolant ttua reactor coolant temperatures cin <!

temperaturesbetweenthedomeangthe .the dome'and in'the bottom head drain, bottom head drain are within 145 F.' - shallibe compared and permanently

' logged.=

c

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3.6.A & 4.6.A

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BASES l

Thermal and Pressurization Limitations i The requirements for the reactor vessel have been identified by evaluating the need for its integrity over the full spectrum of plant conditions and events.

l This is accomplished through the Station Nuclear Safety Operational Analysis (Appendix G) and a detailed functional analysis of' the reactor vessel. The I limits expressed in the technical specification for the applicable operating states are taken from the actual Nuclear Safety Operational Requirements for the reactor vessel as given in Subsection IV-2.8 of the Updated Safety Analysis Report.

The components of the nuclear system pressure boundary are constructed so that j its initial maximum nil-ductility transition temperature (RT NDT) is not' greater I than 40'F, as cited in Subacetion IV-2.5 of the Updated Safety Analysis Report.

The heatup-cooldown and hydrostatic test minimum pressurization temperatures were l calculated to comply with the recommendations of Appendix G of Section III, ASME Boiler and Pressure Vessel Code, 1972 Summer Addendum. .

1 The temperature versus pressure limits when critical which are presented in i Figure 3.6.1.b assure compliance with Appendix G of 10CFR50.  ;

I Tightening the studs on the reactor vessel head flexes it slightly to bring together the entire contact surfaces adjaer.nt to the 0-rings of the head and vessel flange. The reactor vessel head flange and head are constructed ,

so that their initial maximum NDTT is 20*F, as cited in Paragraph IV-2.5 of the l Updated Safety Analysis Report. Therefore, the initial minimum temperature at 1 which the studs can be placed in tension is established at 80*F (20*F + 60*F). j The total integrated neutron flux in the head glange rggion will be less than that {

at the core mid-plane level by a factor of 10 or 10 ,therefore,tgymaximum '

calculated fluence in the head flange r:gion will be far below 1 x 10 nyt. l With such a low total integrated neutron flux in the head flange region, j there will be no detectable or significant NDTT shif t, and the minimum stud tightening temperature remains at 80*F.

1 The reactor vessel is designed in accordance with the ASME Boiler and Pressure Vessel Code,Section III, for a pressure of 1250 psig. The pressure limit of 1035 psig represents the maximum expected operating pressure in the steam dome when the station is operating at design thermal power. Observation of this limit assures that the operator remains within the envelope of conditions considered by Chapter 14 of the Updated Safety Analysis Report.

Stress analyses have been made on the reactor vessel for both steady-state and transient conditions with respect to material fatigue. The results of these analyses are compared to allevable stress limits. The apccific conditions analyzed included a maximum of 120 cycles of normal startup and shutdown with a heating and cooling rate of 100*F per hour applied continuously.over a temp-erature range of 100*F to 546*F. The expected number of normal heatup and cool-down cycles to which the vessel will be subjected is 80.

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m_ -

,6 3.60A & 4.60A BASES (cont'd)~

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As described in the safety analysis report, detailed stress analyses have been made on the reactor vessel for both steady-state and transient conditions with respect to material fatigue. The results of these analyses are compared to allowable stress limits. Requiring the coolant temperature in an idle re-circulation loop to be within 50 F of the operating loop temperature before a recirculation pump is started assures that the changes in coolant temperature at the reactor vessel nozzles and bottom head region are acceptable.

The coolant in the bottom of the vessel is at a lower temperature than that in the upper regions of the vessel when there is no recirculation flow. This J colder water is forced up when recirculation pumps are started. This will not i result in stresses which exceed ASME Boiler and Pressure Vessel Codeg Section j III limits when the temperature differential is not greater than 145 F. j i

The first surveillance capsule was removed at 6.8 EFPY of operation and base I metal, weld metal and RAZ specimens were tested. In addition, flux wires were )

tested to experimentally determine the integrated neutron flux (fluence) at the I surveillance capsule location. The test results are presented in General Electric Report MDE-103-0986. Measured shifts in RT of the base metal and weld metal i werecomparedtopredictedvaluesperRegu1NIryGuide1.99, Revision 1. The  !

measured values were higher than predicted, so the 1.99 methods were modified to reflect the surveillance data. The test results for the flux wires were used i with analytically determined lead factors to determine the peak end-of-life (EOL) ]

fluence at the 1/4 T Vessel wa1 depth The value corresponding to 40 years operation (32 EFPY) is 1.5 x 10{8 n/cm2 .

The adjusted reference temperature (ART) of a beltline material is defined as the initial RT plus the RT shift due to irradiation. The curves of l Figures 3.6.1.gD1nd 3.6.1.b rk2Iect a beltline ART of 110'F, making them valid for operation up to 12 EFPY. Figure 3.6.2, the pressure test curve, includes curves with ART values for 8,10 and 12 EFPY to provide more flexibility in pressure testing. Figure 3.6.2 also has a separate curve for the bottom head region. The bottom head curve does not shif t with increased operation. Therefore, the bottom head temperature can be monitored against lower temperature requirements than the beltline during pressure testing.

B. Coolant Chemistry Materials in the primary system are primarily Type-304 stainless steel and Ziracloy cladding. The reactor water chemistry Ibnits are established to provide an environment favorable to these materials. Limits are placed on conductivity and chloride concentrations. Conductivity is limited because it can be continuously and reliably measured and gives an indication of abnormal conditions and the presence of unusual materials in the coolant. ' Chloride limits are specified to prevent stress corrosion cracking of stainless oteel.

Several investigations have shown that in neutral solutions some oxygen is required to cause stress corrosion cracking of stainless steel, while in the absence of oxygen no cragking occurs. One of these is the chloride-oxygen relationship of Williams , where it is shown that at high chloride concentration little oxygen is required to cause stress corrosion cracking of stainless steel, and at high oxygen concentration little chloride is required to cause cracking.

These measurements were determined in a wetting and drying situation using alkaline-phosphate-treated boiler water and thereforat are of limited significance to BRR conditions. They are, however, a qualitative indication of trends.

1 W. L. Williams, Corrosion 13, 1957, p. 539t.

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4 B

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' INTENTIONALLY LEFT BLANK"

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1 l

4 1600 I I.

VAUD TO 12 EFPY

.k 1400 ADJUSTED BELTLINE, 1/4T FLAW, ART = 110*F 1200 T 1000 h

a k

5 800 E

w w

E 600

, SAFE l

OPERATING l

REGION . _

400 NON BELTLINE FW NOZ2LE UMITS, 1/4T FLAW, RTNOT=28*F 200

/ BOLT PRELOAD TEMPERATURE = 80*F FLANGE REGION RTNDT = 20*F e

0

'N 200 390 MINIMUM VESSEL METAL TEMPERATURE (*F)

Figure 3.6.1.a Minimum Temperature for Non-Nuclear Heatup or Core Cooldown Following Nuclear Shutdown 155 t

l 1800 l i

l VALID TO 12 EFPY k

l 1

1400 , I ADJUSTED BELTLINE 1/4T FLAW, ART =110*F l

1200 1000 I l s

W 800

(

r a

600 NON 8ELTLINE SAFE FW N0ZZLE UMITS - OPERATING PLUS 40'F,1/4T FLAW REGION RTNOT = 28'F 400 ,

FLANGE REGION RTNDT = 20'F; MINIMUM PERMISSIBLE 200 " TEMPERATURE = 80*F .#

PER 10CFR50 8f APPENDIX G s

4 0

0 100 200 300 MINIMUM VESSEL METAL TEMNRATURE ('O Figure 3.6.1.b Minimum Temperature for Core Operation (Criticality) -

Includes 400F Margin Required by 10CFR50 Appendix G

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l 1800 BOTTOM EFPY HEAD REGION 8 10 12 l 1400 l l }* f I //!

f / //

/ ///

I // /

/ // /

BELTLINE CURVES.

1/4 T FLAW,

/ f/

) I /

/

ADJUSTED AS 1000 j f f /

SHOWN; EFPY ART (*F) y

! / /// a di "o

4

'2 g 800 / /// SAFE l

E [ r

/)[ OPERATING REGION i ///

///

600 f,r f 110'F =

1 400

/

312 psig

\

- -- BOLT PRELOAD 200 l ' TEMPERATURE FLANGE REGION = 80*F j [ RTNOT = 20*F 0

100 200 300 0

MINIMUM VESSEL METAL TEMPERATURE ('F)

Figure 3.6.2 Minimum Temperature for Pressure Tests Such as Required by Section XI 157

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