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A'CCESS I ON NBR; 8012080335 DOC» DATE,'0/11/21 40TAR IZED: NO DOCKE)T

FACIL:50-275 0 j ab1 ot CanyonI Nuc 1 ear Power P 1 ant r Unit ir Paci f i cr Ga 0500027550"323 DiabloI CanyonI 4uclear Power Plantr Unit 2g Pacific Ga 05000323

AUTH'AME AUTHOR AFF)ILIIAT I ON

CRANErP;AD P)acific Gas 8 Electric Co;.,RKC IP, NAME RECLPCE~4r'f frlLZATION

MIRAGLIIAE f » J» Resource 8 Scheduling Branch,

SUBJECT: Forwards resoonse to, NRC. 780125 ltr re long"termoverpressut e tr ancient protection.lnc)ludes descriptionI oflong term sys to be employed at facilities,.

DISTRIBUTION CDDE.: BOOIS COPIES RECEIVED:LITR j i ENCL) j~g SIZEi:TITLE: PSAR/FSAR. AMOTS and. Rel ~ted Corr espondence

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PACIFIC GAS AND ELECTRIC COMPANYP. O. BOX 7442 ~ 77 BEALE STREET, 31ST FLOOR, SAN FRANCISCO, CALIFORNIA94106

TELEPHONE (415) 781-4211 TELECOPIER (415) 543.7813

MALCOLMH. ITUR BUSHVICE PRESIDENI AND OENERAL COUNSEL

ROBCRT OHLBACHASSOCIAIE OENERAL COVRSEL

CHAR LCS T. VAN DCUSCNPHILIP A. CRANC, JR ~

HCNRY J. LRPLANTCJOHN S. ESISSON

ARTHUR L. HILLMAN.JR ~

CHARLCS W, THISSCI LIDANICL e. SISsoN

ASEIITAST EESEEAL COUNCIL

November 21, 1980DIL~ EST L HA11IOK0LCNN WEST J1JO ~ EI'H I KELLYHOWAIIDV DOLU~JAHED D,LOS ~ OOHRUDEST L, OOSOONPETES WT HAN~ ONERRIDNAAOt LOSKCDAVIDL LUOVIOSOIE

DAVIDW,ANOCSSONDIANA~ EASHAU~ ENLEIDH O CAS ~ IOYAUDSCTDAINE~WILLIANH C DNA 1 OSDONALD0 CSICK ~ OHDAVID0 OIL~ EST~EEVER ~'1EENWALOJUAN H, JATOt' RONALDLAUPHEINESHASSYW LOUD J1A. RISK IISKCNEICRIONASO L HEI~ OROSES J I CT ~ ASRO ~ EAT R RIOCETTDHIDLEYA OANDESSONJO ANN ~ NATTE1LONI~ C VINCENT~ NISI.CVA WDOKENNETH YARD

CDNASD J HODANNEYDAN 0*AYSON LUS ~ OOKJACK t t'ALLIN JSOEIINASD J DELIAOANTAJO ~ NUA SAA LCVJOSEPH O ENOLCST J1RD ~ CAT L HASAI~DOUOIAS A ODLE ~ SY

~ ENIOS COUNSEL

J, PCTCS OAUNOAIITNC1OTCVCN P DUSKEPANEIACNAPAELLCHIDHAEL0 OESNAIUU~DADY P ENOINAOJOHN H PAVEPATSIOK 0 0OLOtN~ ASIAY HAYNtSRISHASD 0 JUNC ~HCSCK E LI~ SONJOHN R LOWR DUCAT 0, HOLENNAN1ICINASO H HOS ~J, HIDNA~ L RE IDENSAC NIVOS E DAHSOND U C AN1 LCVI1 ~ C 1 IttJACK W, SHUCKDAVIDJ WILLIAN~ OHOSUOC R WO1THINDTON

ATTOSN CEO

Mr. Prank J. Miraglia, Jr., ChiefLicensing Branch No. 3Division of LicensingU.S. Nuclear Regulatory CamissionWashington, D.C. 20555

Re: Docket No. 50-275Docket No. 50-323Diablo Canyon Units 1 and 2

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BDear Mr. Miraglia:

Enclosed is information responding to the letter franMr. John Stolz dated January 25, 1978 concerning long-tenn OverpressureTransient Protection. The response contains a description of thelong-term systems to be employed at Diablo Canyon Unit 1 and Unit. 2.

Kindly acknmrledge receipt of this material on the enclosedcopy of this letter and return it to me in the enclosed addressedenve pe.

ETB AI1 ~ 'I~ I

P"S'„

I'El l '5

WIId

g~

EnclosureCC w/enc. 1 Service List

Very truly yours,

8 03,208@

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0Startu and Shutdown Overoressure Protection

l.'dentify and justify the most limiting pressure transients caused by mass

input and heat input.,

a

The most limiting pressure transients caused by mass input and heat input

were identified and justified by Westinghouse for the Westinghouse Owner's

Group on Reactor Coolant System Overpressuri zation, and documented in the

repo'rt entitled "Pressure Mitigating Systems Transient Analysis Results"

dated July 1977 with a supplement dated September 1977.

A) Mass Input

The most limiting pressure transient, due to mass input was identified in

Section 2.3 of the report as the inadvertent starting of a intermediate

head safety-injection pump at, low reactor coolant system pressure (Page 2«13).

B) Heat Input

The most limiting pressure transient du» to heat input was identified

in Section 2.4 of the report as that produced by reactor coolant loop

temperature asymmetry coincident with water solid operation and reactor

coolant pump start (Page 2-19).

2. Show that the overpressure protection is provided (does not violate Appendix G

limits) over the range of conditions applicable to shutdown/heat-up operation.

A) Mass Input

A transient analysis has been performed by Westinghouse for the inadvertent

actuation of the safety injection pump, which is the worst transient

event. The results show that a maximum pressure of 490 psia will be

reached in the RCS; which is within the allowable limits. (See

Technical Specification Section 3/4.4.9.) The analysis takes into

account the single failure criteria; one PORV was assumed to be

unavailable for RCS letdown.

t

«2

B) Heat Input

An analysis was performed by Westinghouse for the RCP start whichr

assumed that the .RCS was water solid at the initiation of the eventE

and that a 50'F mismatch existed between the RCS and the steam

generators. The peak pressures calculated were below those of the

safety injection pressurization analysis.

C) Analysis

A, reactor vessel fracture mechanics analysis was performed to

evaluate the consequences of such a pressure peak. The analysis7

determined the maximum calculated flaw size acceptable on the

vessel inside diameter at 12 EFPY. The methods and conservatisms

used to derive the maximum calculated flaw size are from Appendix G

to Section III of the ASIDE Code.

The analysis determined the maximum calculated flaw size for a

533 psia pressure at 100'F. The Unit 1 material properties used

in the analysis are 0.35 weight, percent copper, 0.018 weight

percent phosphorous, and an initial RTgDT of O'. The 12 EFPY

fluence at the surface is 2.6 x 101g n/cm2. The resulting

maximum acceptable flaw size is 1.5 inches. These results

demonstrate that the pressure peak consequences do not impair

vessel integrity or plant safety at 12 EFPY.

3 ~ Identify and justify that the equipment will meet pertinent parameters

assumed in the"analysis (e.g., valve opening time, signal delay, valve

capacity).

A) Valve Opening Times

The Westinghouse analysis assumes a valve opening time of 3 seconds

(Section 1.4.2, Pages 1-8). PGandE has tested these valves and measured

opening times of less than 2 seconds. (Surveillance Test Procedure V-3-J-I.)

B) Signal Delay

The subject of signal delay was included in the measurement described in

Part (A) above.

C) Valve Capacity

The characteristics of the Diablo Canyon pressurizer power-operated relief

valves and the reference valve used in the Westinghouse analysis are given

below:

W ReferenceValve

Diablo CanyonValve

Type:

Body Size:

Globe

2 inch

Globe

2 inch

Valve Trim: linear linear

Maximum Cv

Opening Time (Sec):

50

3.0 2.0

The difference in valve flow coefficients (c ) is offset by the increasev

in opening time (2 seconds vs. 3 seconds).

4. Provide a description of the system including relevant P&I drawings and

electrical schematics.

A schematic of the System is attached. There are two independent channels,

one connected to pressurizer power-operated relief valve PCV-455C, and the

other to PCV-456. The channel connected to PCV-455C is described below.

The channel connected to PCV-456 is similar.

V

The system opens PCV-455C when all four of the following conditions are met:

0. a) Temperature sensed .by Temperature Comparitor TC-413A is below 330 F,

b) The enable switch located on the main control board is in the "enable"

position,P

c) Pressure sensed by Pressure Comparitor PC-405D is greater than 450 psi,

and

d) Th' .PORV Control Switch is the in the "auto" position.

To provide for alarming of the system, a main annunciator input is activated0

when the temperature as sensed by Temperature TC-413A is below 330 F and the

enable switch on the main control board is not in the "enable" position.

5. Discuss how the system meets the criteria.

A) Operator Action

The system is completely automatic. ,Once enabled by the operator before

startup, the system will open the pressurizer power-operated relief ialves

whenever the pressure exceeds 450 psi coincident with reactor coolant0

csystem temperature below 330 F.

B) Single Failure

There are two separate and independent systems. The failure of either

system would not affect the remaining system.

C) -Testability

The system is testable at all times. The pressurizer power-operated

relief valves are in series with motor-operated block valves which may

be closed during testing. Test signals may be injected into the

appropriate control circuits and the position of the valve monitored

and timed.

D) Seismic and IEEE 279 Criteria.S

All components in the system meet seismic Category I and IEEE 279 Criteria.

The electrical portions of the system are powered from invertors supplied

by the station battery. The air to the valve is backed up by bottled

nitrogen.

.6. Discuss the administrative controls required to implement the protection system.

Instructions to enable the overpressurization protection system will be

included in Plant Startup Procedure (L-l) and Plant Cooldown Procedure,

(L-5). A Technical Specification requiring use of the system will also

be added.

OVFPP)FESS''E PA?OPEC TJOAf'HANNELA

OverpressureProtectionSwitch("Enable" )

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PC403

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Open

PORV

PCV-45SC

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