DCL-03-092, Response to NRC Request for Additional Information Regarding License Amendment Request 02-05, Revision to TS Table 3.3.1-1, Reactor Trip System Instrumentation & Revised Reactor Coolant System Flow Measurement

Response to NRC Request for Additional Information Regarding License Amendment Request 02-05, Revision to TS Table 3.3.1-1, Reactor Trip System Instrumentation & Revised Reactor Coolant System Flow Measurement

ML032190615
Person / Time
Site:	Diablo Canyon
Issue date:	08/01/2003
From:	Becker J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-03-092
Download: ML032190615 (14)

Text

PacificGas and ElectricCompany James L. Becker Diablo Canyon Power Plant Vice President -Diablo Canyon PO. Box 56 Operations and Station Director Avila Beach CA 93424 August 1,2003 805.545.3462 Fax: 805.54.4234 PG&E Letter DCL-03-092 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Resnonse to NRC Reauest for Additional Information Regarding License Amendment Request 02-05, "Revision to Technical Specification Table 3.3.1-1.

'Reactor Trip System Instrumentation.' and Revised Reactor Coolant System Flow Measurement"

Dear Commissioners and Staff:

On April 22,2003, the NRC staff identified additional information required to complete the evaluation associated with PG&E License Amendment Request (LAR) 02-05 for Diablo Canyon Power Plant (DCPP) Units I and 2.

LAR 02-05 proposes to revise the term "minimum measured flow per loop" to "measured loop flow' in the allowable value and nominal trip setpoint columns for the Reactor Coolant Flow-Low reactor trip function contained in Technical Specification 3.3.1 Table 3.3.1-1, "Reactor Trip System Instrumentation." In addition, LAR 02-05 proposes to allow an alternate method for the measurement of reactor coolant system (RCS) total volumetric flow rate through measurement of the elbow tap differential pressures on the RCS primary cold legs. LAR 02-05 was submitted by PG&E letter DCL-02-097, 'License Amendment Request 02-05, Revision to Technical Specification Table 3.3.1-1, 'Reactor Trip System Instrumentation,' and Revised Reactor Coolant System Flow Measurement," dated August 27, 2002.

Previously, PG&E provided responses to NRC requests for additional information in PG&E letter DCL-03-056, 'Response to NRC Request for Additional Information Regarding License Amendment Request 02-05, Revision to Technical Specification Table 3.3.1-1, 'Reactor Trip System Instrumentation,' and Revised Reactor Coolant System Flow Measurement," dated May 15, 2003, and PG&E letter DCL-03-079, "Response to NRC Request for Additional Information Regarding License Amendment Request 02-05, Revision to Technical Specification Table 3.3.1-1,

'Reactor Trip System Instrumentation,' and Revised Reactor Coolant System Flow Measurement," dated June 26, 2003.

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance )

Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• South Texas Project

• Wolf Creek (1) )

Document Control Desk PG&E Letter DCL-03-092 August 1, 2003 Page 2 PG&E's response to the April 22, 2003, request for additional information is included in Enclosure 1.

The additional information does not affect the results of the safety evaluation or no significant hazards consideration determination previously transmitted in PG&E letter DCL-02-097.

If you have any questions regarding this response, please contact Stan Ketelsen at 805-545-4720.

Sincerely, James R. Becker Vice President - Diablo Canyon Operations and Station Director kjs/4328 Enclosures cc: Edgar Bailey, DHS Thomas P. Gwynn David L. Prouix Diablo Distribution cc/enc: Girija S. Shukla A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• South Texas Project

• Wolf Creek

PG&E Letter DCL-03-092 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Docket No. 50-275 Inthe Matter of ) Facility Operating License PACIFIC GAS AND ELECTRIC COMPANY) No. DPR-80

)

Diablo Canyon Power Plant Docket No. 50-323 Units I and 2 Facility Operating License No. DPR-82 AFFIDAVIT James R. Becker, of lawful age, first being duly sworn upon oath states that he is Vice President - Diablo Canyon Operations and Station Director of Pacific Gas and Electric Company; that he has executed this response to the NRC request for additional information on License Amendment Request 02-05 on behalf of said company with full power and authority to do so; that he is familiar with the content thereof; and that the facts stated therein are true and correct to the best of his knowledge, information, and belief.

JamesBcBecker Vice President - Diablo Canyon Operations and Station Director Subscribed and sworn to before me this 1st day of August 2003.

'Wtay ublic _

County of San Luis Obispo State of California Smmis8ion iE380 Notary Public - California San Luis Obispo County 200 M Corm. Expires Jan 12 S

Enclosure 1 PG&E Letter DCL-03-092 PG&E Response to NRC Request for Additional Information Regarding License Amendment Request 02-05, "Revision to Technical Specification Table 3.3.1-1, 'Reactor Trip System Instrumentation,'

and Revised Reactor Coolant System Flow Measurement" Questions Received on April 22, 2003:

NRC Question 1 Provide justification that the kinetic energy effects between the hot leg and the cold leg have a negligible impact on the elbow tap flow measurement.

PG&E Response The difference in the kinetic energy (KE) per unit mass between the reactor coolant system (RCS) hot leg and cold leg resistance temperature detectors (RTDs) has been calculated to be -0.00018 British thermal units (BTU) per pound mass for Diablo Canyon Power Plant (DCPP) Units 1 and 2. This difference is considered to be negligible and therefore the effects of KE can be ignored for the calculation of elbow tap flow using baseline RCS flow calorimetrics. The calculation of the difference in the KE per unit mass between the RCS hot leg and cold leg RTDs is contained in Enclosure 2.

NRC Question 2 What was the heat loss rate between the RCS hot legs and cold legs assumed in the RCS calorimetric calculations? What were the RCS makeup and letdown mass flow rates and the locations that were assumed in the calculations?

PG&E Response The net heat loss between the RCS cold and hot leg RTDs on the core side that is currently used by PG&E in the RCS flow calorimetric calculations is 1.089 million BTU per hour for each loop. Individual charging flow energy, reactor vessel heat loss, pressurizer spray flow energy, control rod drive mechanism heat loss, and RCS piping heat loss terms are quantified in the heat loss calculation. The heat loss calculation is contained in PG&E Calculation N-1 96 Revision 0 which is attached in Enclosure 3. It is noted that the baseline flow calorimetrics that were performed in Cycles I and 2 for DCPP used an older value of 1.835 million BTU per hour instead of 1.089 million BTU per hour. This older value resulted in slightly lower (more conservative) RCS baseline flows for the elbow tap normalization.

The heat loss calculation considers a charging flow of 25,025 pounds mass per hour (50 gallons per minute at a temperature of 100 degrees Fahrenheit and a pressure of 2250 pounds per square inch absolute) that enters the RCS via the normal charging line. The charging flow is based on a letdown flow of 75 gpm, a reactor coolant pump seal return flow of 11 gpm, and a net RCP seal injection flow of 25 gpm.

I

Enclosure 2 PG&E Letter DCL-03-092 Evaluation of Effect of Kinetic Energy Difference Between RCS Hot and Cold Leg RTDs on RCS Flow Calorimetric With the kinetic energy term, the loop reactor coolant system (RCS) flow calorimetric equation becomes:

M = Q/(Ah + A(KE)) [Equation 1]

M = loop mass flowrate (pounds mass (Ibm)/sec)

Q = net heat removal between hot and cold leg resistance temperature detectors (RTDs) (British thermal units (BTU)/sec)

Ah = enthalpy rise between cold leg and hot leg RTDs (a positive value)

(BTU/Ibm)

A(KE) = increase in kinetic energy (KE) per unit mass between RCS cold leg and hot leg RTDs (BTUIlbm)

Note that if A(KE) is negative, then it is conservative to ignore it.

The ratio between the KE at the hot leg and the KE at the cold leg is given by:

(VHNC)2 = (PC2 dc4)/( PH2dH ) [Equation 2]

where KE =V2/(2x32.174) (foot pounds force/Ibm) [Equation 3]

M = pcVcAc = pHVHAH (Equation 2 is derived from this conservation of mass equation)

M = loop mass flow rate (Ibm/second (sec))

p = water density (Ibm/cubic feet (ft3))

V = water velocity (feet (ft)/sec)

A = flow area (square feet (ft2))

d = pipe inside diameter (ft) 1

Enclosure 2 PG&E Letter DCL-03-092 The RCS flow calorimetric is performed at (or near) 100 percent reactor thermal power.

At full power, the following nominal conditions exist in the RCS cold and hot legs at Diablo Canyon Units I and 2.

RCS Cold Leg RCS Hot Lea dc = 27.5" = 2.292 ft dH = 29' = 2.417 ft Ac = 4.1247 ft2 AH = 4.5869 ft2 Tc = 540 degrees Fahrenheit (F) TH = 604 F Pc = 2300 pounds per square inch absolute (psia) PH = 2250 psia PC = 47.526 Ibm/ft3 PH = 42.817 Ibm/ft3 hc = 534.79 BTUA/bm hH = 618.97 BTU/lbm Then Equation 2 gives:

(VHNC)2 = 0.9962 Because this ratio is less than 1.0, A (KE) is negative in Equation 1. Therefore, it is conservative to ignore this term in the RCS flow calorimetric calculation. The magnitude of this conservatism is quantified below.

The nominal volumetric flow rate at the RCS cold leg is 91,000 gallons per minute, which is 202.749 f 3 /sec.

The velocity at the RCS cold leg is given by:

(202.749 ft3 /sec)/(4.1247 i 2) = 49.155 ft/sec Equation 3 gives the kinetic energy per unit mass at the RCS cold leg as:

(49.155) 2 /(2x32.174) = 37.55 ftilbf/lbm = 0.04825 BTU/lbm The kinetic energy per unit mass at the RCS hot leg is:

(0.04825 x 0.9962) = 0.04807 BTU/lbm The A (KE) term in Equation I is:

0.04807-0.04825 = -0.00018 BTUAbm-2

Enclosure 2 PG&E Letter DCL-03-092 The A (KE) term in Equation 1 is very small compared to the enthalpy rise between the cold leg and hot leg RTDs ternm (Ah) and thus the increase in KE per unit mass between the cold leg and hot leg R1bDs can be ignored.

Therefore, the effects of KE can be ignored for the RCS flow calorimetric calculations.

3

Enclosure 3 PG&E Letter DCL-03-092 PG&E Calculation N-196 Revision 0

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D. Control Volume Equation and Simplifyir.g Approximations C C. Solution of Equation For Ket Heat Input 11I. Sunay ZV. References

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NucleAa Power Generation Noulea Technical Services Ii.,adtui Kuain~teoritl ng ENGINEERING CALCULATIONS S. Purpose The purpose of this calculation file Is to revive the Reactor Coolant System.

(RCS) net heat Input for the *CS flow calorimetric (STP R-261 using the latest RCS net heat input data obtained from Westinghouse I)l. The new heat addition terms will result In slightly lower calorimetric povers and flows.

This calculation file applies to both DCPP units.

XX. RCS let Beat Input For Flow Calorimetric A. Definition STP R-2( determines the RCS volumetric fleorate at the elbow taps in the

'1 crossover piping. This In accocplished by performing en energy balance across the reactor vessel between the cold leg and hot log RTDs. for each r loop, the flow calorimetric equations ore:

WILL

• w .,.L/(hN-h,4L (EQN. 11 n0M$U V& X VNLL/-.020823 (EQN. 21

'Q-.L* Q_ A tEQN. 3)

Q..L_

• Q8. "iNP1 (lEQN 4 -

where 4 w core power going to loop L (SD1'J/hr)

A* the net heat addition between the hot and cold log XTV# on th core side divided by 4 (BTy/hr):

KP)Ak 12.24 X 100 BTU/hr a total IPHA divided by 4 gII wa the RM loop mass flowrate at the hot 1to RTSD 49tenldo ty the flow calorimetric (lb,/:r) b, . hot leg enthalpy In loop L (D2U/3bT -

a cold leg enthalpy In loop aL, 4T/UbM:

v

• cold log etcitfic valwo It'tlta,.

GPK, volamtric flowrate at elbow tope nOP:

we ane iterested La calculating Pr.Zared ys c at. ft.:

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Hucleat Power Generation Nuclear Technical Services Reactor Kngineering ENGINEERING CALCULATIONS D. Control Volume Equation and simplifring Approzimations The selected control volume will enclose the reactor vessel and will includet the RCS piping between the reactor vessel and the hMt leg RSDs and between the reactor vessel and the cold leg RDs. Normal charging and the pressurizer spray line cross the boundary of this control volume. Hovever.

letdown and the pressurizer surge line do not 12. 3). Then tbe energy input terms are given by core power, the four cold legs, and normal charging. The energy output terms are given by the four hot legs, normal pressurizer spray line, and the radiative and convective heat losses fro: the reactor vessel.

control rod drive mechanisms, and piping 1vithin control volume).

An energy balance over the control volume yields the following equation.

Q_ wov (v I )Y * (wchrl (wcheI, fVwdi,).

• Qv Q . QcU + Q,"* (woh),d (w*ho) r- (wf^))

• 4vlh), (E(ON. Si) where the subscript CHO refers to charging flow.

To simplify this calculation, we will assume perfect symetry between the four cold legs and between the four hot legs. i.e., assume the Cullovtngs

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WQe/4 OnQe/I + QV/4

• Q.,,,/4 +Qrtctu/4 +Qpp.j/4 IEQN. 7)

C. Solution of Equation For Not Beat Input In Equation 7. 4r in calculated from wck. QC. Qa,. Q adn,.Qcgu. are taken directly froa Reference 1. Q,, for the control volume will be approximated by taking half of the total piping losses given in Reference 1.

The charging flow to use In the above control volume equation (call It

,Charging*) is the portion of the total charging flow vhich soee Into the RCS via the normal charging line. The total measured charging flow (including seal injection) i6oJ6 gp and the normal letdown flow gnot including seal return) is 75 gpm 11. Since 75 gpm is leaving the RC5. 7S gpm must be entering the RCS via the charging and MCV seal injection. Call

• Seal Injection' the -portion of the ACV seal injection flow which goes Into 7 1. ,- - -

the RCS. Then , -1c 4

"Charging* + *Seal Injection'* 75 gpo I .f I -,tg Also, the total flow leaving the CvCS (86 gp=) must equal the total flow returning to the CVCS. Therefore,

• Letdown + Seal Return" i6 gpm Since 'Letdown' a 7S 9m.then "Seal Return a 16675 a 11 Cp=. For each RCP, C,

the seal injection flow is 9 gpm (1. Then the total RCF seal Injection flow is 4x9 a 36 gpm. Then

'Seal Injection-

• 36 *11

• 25 gpm and Charging' a 75 * "Seal Injection'

• 75

• 25

• S0 VpM Therefore, . a (50 gpm)(62.4 lb/ft')(6.0208333) a 21025 lb./hr. The charging water density corresponds to z00 *F and 2210 psi&. And ht

• 134.04 STU/lb. at S40 *V and 22S0 psia. Then Or

• 12S025 lb,/hr) S54.64 STU/lb,) a 13.30 FMTV/hr.

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Nurlea: Powet rgeella-tiaf Hurlear Technical Sorvices Pu~ac~tor Engineering ENGINEERING CALCULATIONS Next. we have from Reference 1:

u 11.72 HBTJ/hr Qmv

• 0.23 BTtJ/hr Q, 0.41 ISBTU/hr 1.9t IMB7U/hr QPVW 0.15/2 0.07S MBTU/hr C.

Then equation 7 gives

-v 413.31

• 11.72 * .23 * .41 + 1.58 * .OS1/4 1,0£ 9 MTS2hr III. Sumz The appropriate net heat input value to use in converting core Power to loop" power in the STP R-26 flow calorimetric is approximately 1.061 NBmJ/hr for each loop.

XV. RoferenceJ (1) Westinghouse Letter IG359S-572, 4ROviseG RC$ Pet Kest toput Calculation, J.C. Hoebel to N.J. Angus, 5/13/55. PG&Z chron. So.

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(2) VCPP OVID 106707, Rev. 25, Unit 1.

I3) XCPP OVID 107707, Rev. 26, Unit 2.

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