ML19269E333

Submits Requested Info Re Analysis on Capability of Dry & Isolated Steam Generator to Start Auxiliary Feedwater Pump 30 Minutes After Loss of All Main Auxiliary Feedwater & Test Results for Anticipatory Reactor Trip Sys

ML19269E333
Person / Time
Site:	Davis Besse
Issue date:	06/23/1979
From:	Roe L TOLEDO EDISON CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
NUDOCS 7906270225
Download: ML19269E333 (11)

Text

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LOWELL E. RCe Docket No. 50-346 n.am.o. t 64c, et .. C.v# 30*s'96 License No. NPF-3 mu :nm2 Seria'. No. 522 June 23, 1979 Director of Nuclear Reactor Regulation Attention: Mr. Robert N. Reid, Chief Operating Reactors Branch No. 4 Division of Operating Reactors United States Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Reid :

This letter transmits the following information requested by G. R. Mazetis:

1) An analyc4.s on the capability of a dry and isolated steam generator to start an auxiliary feedwater pump 30 minutes after the loss of all main and auxiliary feedwater.

2) The test results for anticipatory reactor trip system.

Yours very truly,

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Docket No. 50-346 License No. NPF-3 Serial No. 522 June 23, 1979 Attachment 1 Question 1 Discuss the ability of the secondary system to support AFW steam turbine operation at 20 minutes af ter loss of feedwater to the generator.

Response

Davis-Besse Nuclear Power Station Unit 1 (DB-1) is designed to redundantly isolate each steam generator (SG) upon initiation of SFRCS. The steam generators are not cross-connected on either the feed or steam system side when isolated. In any loss of feedwater condition, SFRCS isolates the steam generators and starts the auxiliary feedwater (AFW) steam turbines to provide auxiliary feedwater flow to the generators within 40 seconds. If for some reason one or both redundant safety grade AFW trains do not initiate for thirty minutes there will be adequate pressure to start the pumps. This is illustrated by both calculation and experience at 9B-1. The s;quence of events would be as follows: a) LOFW b) Reactor trip c) SFRCS - isolated steam generators (assume no AFW initiation) d) Decay heat removal due to primary to secondary heat transfer to steam generator inventory, boiling off the inventory to atmosphere via main steam safety valves. Secondary system pressure 1050 psigc>550 F. e) As soo' as the generator inventory boils of f from a reactor trip at any preefous power level, decay heat removal to that generator is lost. If both generators are dry, all decay heat is removed via the boil-off of the primary system through the PORV, pressurizer code safety valves and/or break. This has been analyzed in Volume III of the " Evaluation of Transient Behavior and Small Reactor Coolant System Breaks in the 177 Fuel Assembly Plant", dated May 16, 1979. This will let pressure f all to main steam safety reseat setpoint and isolate all dry steam loss from the steam generator. With this total SG isolation the stes.m genera-tor should be at approximately 1000 psig and will remain pressurized indefinitely. During this time, the dry superheated steam in the steam generators will be at primary system temperature and there will be no heat transfer through the steam generator. There will be 3412 Cu.Ft. (221600 lb.) of dry surerheated steam in the SG at 1000 psig available to start the AFN pumps. At a full rated flow, the AFU turbine conserva-tively requires 33,000 lb./hr. steam flow. The turbine starts in 30 seconds after steam inlet valves start to open which means that it will require about 275 lbs. of steam to start and bring the AFW pump up to full speed at full rated flow against full steam generator pressure. As a bounding argument to this case, DB-1 has had one event in which a steam generator did not receive AFW when actuated on September 24, 1977. 5

Docket No. 50-346 License No. NP F-3 Serial No. 522 June 23, 1979 Attachment 1 During this event one AFW pump was running at 2600 rpm while the SG was dry. During this ccndition the SG pressure reduced to about 650 psig in 16 minutes. At that time the operator manually increased the AFW pump speed and the SG pressure immediately increased, due to the introduction of AFW to the SG. Additional details are found in the Supplement to the September 24, 1977 Licensee Event Report dated November 14, 1977. 2131 226

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TEST PROCEDURE FOR THE CONTROL GRADE ANTICIPATORY REACTOR TRIP SYSTEM FCR 79-176

1. PURPOSE The purpose of this procedure is to functionally test the_ Control Grade Anticipato':y Reactor Trip, System - (ARTS) FCR'79-176. This test will also 'show that there is no degrading of the SFRCS. ST 5030.12,

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Channel Functional Test of Rx Trip Module logic and CRD Trip Breaker and ST 5030.13 Channel Functional Test of Manual Ex Trip will be perforned also to show there is no degradation to the RPS trip function.

2. PRECAUTIONS & LIMITATIONS 2.1 During Phase II the SFRCS will be placed in the' half trip condition on Channel 2/4.

2.2 Do NOT_ exceed theJinit of electrically tripping .the_ Reactor _ Trip _. _ Breakers pore than,once per half hour.

3. PREREQUISITES 3.1 The station is in Mode 4 or Mode 5.

Verified Data

                                                             "/         gg              G~/L       /

3.2 The SFRCS is energized and all applicable Iamps are "0N" for present plant conditions. Phase II only. Verified k Date h [[

                                                               /                       ~ C, - Ak 3.3 Circuit 33 in Y3602 has been en      ,1aed.Q(U Verified        (/.ec           Date (o-//-77 U!W                          6 -/1.

3.4 MS 375 is closed. Phase II only Verified Date ([~// -N 3.5 SP 7A is closed. Phase II only. Verified Date [- // -

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3.6 MS 100-1 is closed. Phase II only.

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Verified Date d - //~ W 6-e 2131 229

3.7 ICS 11A is closed. Phase II only. Verified Date 3.8 The EHC has been simulated to the /Q(Npoiht that it can be reset. W"fek-Phase III only.

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Verified Date 3.9 The AC Supply to the CRD has beef disconnected in the CRD cabinets for all SCR Groups. . Verified Dateb~ 3.10 The Breakers to the CRD system are VQQ%cap 1 of being reset. (p ~ /%- Verified - Date (/^- (j ~)V 3.11 Verify that both Blower A and Blower the Mdtor Return Cabinet are operating. Blower A Verified i/ /

e. ,

y ak Date _ Og [ Blower B Verified y /-

                                                                     /   .I-   Date o- ,

Y[@9 3.12 Shift Foreman has given permission to

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this test. Shift Foreman b [ArV)#tp Time /ddd Verified. Dateh' k Floal) owl O (y 0-1G

4. PROCEDURE The procedure is divided into three (3) phases:

Phase I - Testing of the Test Pushbuttons located in C5741, C5742, C5743, and C5744. PhaseII - Testing of the Differential Pressure Switches (Loss of feedwater) Phase III-Testing of the Turbine Trip . 4.1 Phase I 4.1.1 Place the T/G Block Switch HS NI51 in the " BLOCK" position. Verify Q779 status is " BLOCK". Verified Date IY 7 2131 250

e Verify computer / 4.1.2 Reset "A", "B", "C" and "D" Breakers. annunciator point Q777 is not ala . Date / Verified _ 'l

                                                                                        ' / ,f "B" Breaker 4.1.3    In C5741, momentarily depress HS NI47 and verify trips and computer / annunciator oint Q777 alarms.

Verified Date b - - Verify computer / annunciator point Q77 4.1.4 Reset B Breakers. Verified D' ate N /

                                                                                 "A" Breaker 4.1.5    In C5742, momentarily depress HS NI48. Verify trips and computer / annunciator point Q777 alarms.

Verified Dc.te [/ ///

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                                                       /j                                    Q777 4.1.6    Reset   "A" Breaker. Verify   computer  / annunciator po n Verified Date      N! /'
                                                      / \                          "D" and "B" 4.1.7     In C5743, momentarily depress HS NI49. Verify Breakers trip and computer / annunciator pc4.nt Q777 alarms.

D tee b Verified

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Reset "D" and "B" Breakers. Verif _omputer/ annunciator 4.1.8 point Q777 clears. Date // Verified /

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                                                                                    "C" and "A" 4.1.9     In C5744, momentarily depress HS NISO. Verify Breakers trip and computer / annunciator point Q777 alarms.

Verified Date 6 /

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                                                                                 ~/         /'/

Breakers. Verify computer / annunciator 4.1.10 Reset "C" and "A" point Q777 clears. Verified

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Date , //, . 4.2 Phase II 4.2.1 Verify HS NI51 is in the " BLOCK" position, Q779 status is

                          " BLOCK" and computer / annunciator points Q778, Q777 are NOT_  *     -

alarmed. Verified _Date

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2131 231

4.2.2 Valve out and equalize PDIS 2685B. Vent the lov leg to atmosphere and connect a water test pump and test gauge to the high leg. Close the equalizing valve. Verified

                                                  / --
                                                      /             Date 6
                                                                               /       t N i 4.2.3 Slowly increase the test pressure to approximately 200 paid. Verify a dP trip in Channel 4 SFRCS, P702 alarms and the CRD breakers did NOT trip Verified                          Date N
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O /

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4.2.4 Decrease the test pressure to O psid. Verify the SFRCS dP trip reset and P702 clears. Verified Date

                                                     /(                         /      /
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4.2.5 Valve out and equalize PDIS 2686D. Vent the low leg to atmosphere and connect a water test pump and test gauge to the high leg. Close the equalizing valve. Verified A Date d# , 4.2.6 Slowly increase the test pressure gauge to approximately 200 psid. Verify a dP trip in Channel 4 SFRCS, P701 alar =s and the CRD breakers did NOT trip. Verified Date [

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l% 4.2.7 Again increase the test pre (sure on PDIS 2685B to approximately

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200 psid. Verify _ computer / annunciator point Q777 is in_ aiarm,[ and all CRD breakers are tripped. jA Verified Date /

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4.2.8 Decrease the test pressure in PDIS 2685B and PDIS 2686D to O psid. Valve both.PDIS's back into service. Verify the dP trip in SFRCS Channel 4 has cleared and P701 and P702 have cleared. Verified

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Date 6 / ' N / N/ / 4.2.9 Reset "A", "B" , "C" and "D" Breaker . rify computer / ann ciator point Q777 clea;s. j/ Verified, Date 6'/

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2131 232

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• 4.2.10 Independently verify that PDIS 2685B has been returned to service.

Independently Verified b [d Date le Zh9 4.2.11 Independently verify that PDIS 2686D has been returned to service. Independently Verified f> me Date /1!7 Cf 4.3 Phase III 4.3.1 Reset the turbine. Verified

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h Date MJ

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4.3.2 Verify CRD Breakers "A", "B", "C" and "D" are reset. Verified

                                                            /q Date      d
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4.3.3 Verify HS NI51 is in the " BLOCK" position, Q779 status is

                            " BLOCK", and computer / annunciator points Q778, Q777 are Verified                       Date d
                                                        /

4.3.4 Trip the turbine and verify that CRD Breakers "A", "B",

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                            "C" and "D" DO Nar trip.

Verified Date yu - i 4.3.5 Reset the turbine. Verified Date (f l

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4.3.6 Remove the 15% block by using HS NI51. Verify Q779 status is NOT blocked. (,vo/2/ri:L)erified Date d /~ j i < 4.3.7 Trip the turbine. Verify all'CRD breakers have tripped and computer / annunciator point Q777 is in alarm. Verified _date 4.3.8 Place HS NI51 in the " BLOCK" positinn. Verify Q779 status is " BLOCK" and computer / annunciator point Q777 is NOT alarmed. Ver ed Date

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2131 233

4.3.9 C '\l3 Simulate greater than 15% power in the computer. Verify computer / annunciator point Q778 al . Verified Date h S

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4'.3.10 Remove the " BLOCK" using ES NI51. Verify computer /annun-ciator point Q778 clears. Verified a Date 6, / , 4.3.11 Place HS NI51 in the block position. Verified Date //

                                                                  /                          /      /        /

4.4 Connect the AC Supply in the CRD cabinet to the CRD for all SCR Groups, f vfl 1 1 ' Verified ry // Date / ). VV 4.5 Perfom ST 5030.12 on all four (4) RPS Channels. Datecompleted[8b erified Date h

                                           / I   '                /                          /
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4.6 Perfom ST 5030.13. Date completed erified Date f

5. ACCEPTANCE CRITERIA 5.1 The " Test" pushbuttons for the ARTS operated as designed per Phase I.

Verified

                                                                           . ~ . fe,,Date M       [   ,

5.2 The Loss of Feedwater Differential Pressure Switch circuit operated as designed per Phase II. / Verified ' Date / N '

                                                               /                           / 7 5.3 The Turbine Trip circuit and the " Block" function operated as designed      per Phase III.

Verified 7/ Date M /

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2131 234 e}}