AECM-86-0111, Forwards Supplemental Info Re Design Change to Add Interlocks to ECCS Injection Valves,Per NRC 860403 Telcon. Approval of 850812 Proposed Amend to Tech Specs Also Requested

Forwards Supplemental Info Re Design Change to Add Interlocks to ECCS Injection Valves,Per NRC 860403 Telcon. Approval of 850812 Proposed Amend to Tech Specs Also Requested

ML20198R643
Person / Time
Site:	Grand Gulf
Issue date:	05/30/1986
From:	Kingsley O MISSISSIPPI POWER & LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
AECM-86-0111, AECM-86-111, TAC-59440, NUDOCS 8606100155
Download: ML20198R643 (9)

Text

a 9

MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi M P. O. B O X 16 4 0, J A C K S O N, MI S SI S SI P PI 39215-1640 May 30, 1986 O. O. KINGSLEY, JR.

WKE PeEllDENT NUCLE AR OPE R ATK)NS U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D. C. 20555 Attention: Mr. Harold R. Denton, Director

SUBJECT:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Additional Information on Low Pressure ECCS Interlocks AECM-86/0111 By letter dated August 12, 1985, Mississippi Power & Light Company (MP&L) proposed Technical Specification changes to implement a design change to cdd interlocks to the ECCS injection valves. The design change will prevent over pressurization of the low pressure coolant injection system by the higher pressure reactor coolant system due to inadvertent opening of the valves.

Subsequent correspondence and conversations en this subject were culminated at a meeting on April 1, 1986, wherein MP&L proposed positions similar to the alternative positions indicated by the NRC in its November 22, 1985, letter to MP&L.

The purpose of this letter is to provide supplemental information as requested by NRC in a telephone conversation on April 3, 1986, and to request approval of the proposed amendment as provided in MP&L's August 12, 1985, submittal augmented by additional submittals on September 25, October 5, and October 22, 1985. The additional information to support this request is attached.

Yours ly, ODK:vog Attachment cc: (See Next Page) 86061%$

PDR P

\

\ I J13AECM86041803 - 1  : I Member Middle South Utilities System ,

< 7

AECM-86/0111 Page 2 cc: Mr. T. H. Cloninger (w/a)

Mr. R. B. McGehee (w/a)

Mr. N. S. Reynolds (w/a)

Mr. H. L. Thomas (w/o)

Mr. R. C. Butcher (w/a)

Mr.JamesM. Taylor, Director (w/a)-

Office of Inspection & Enforcement U. S. Nuclear Regulatory Comission Washington, D. C. 20555 Dr. J. Nelson Grace, Regional Administrator (w/a)

U. S. Nuclear Regulatory Commission Region II 101 Marietta St., N. W., Suite 2900 Atlanta, Georgia 30323

'J13AECM86041803 - 2

.0

• Attachment to AECM-86/0111 Page 1 of 3 Additional Information on Low Pressure RCS Interlocks The following information addresses two major subjects; i.e., (1) Remote Shutdown Panel Switches and (2) ECCS Piping.

(1) Remote Shutdown Panel Switches As discussed in the April 1, 1986 meeting, key locked control switches separate from the present spring-return-to-auto control switches will be installed on the remote shutdown panel (RSP) which will block operation of the LPCI injection valves via the RSP control. Installation of these key locked control switches will be completed prior to startup following the first refueling outage in compliance with the Facility Operating License Condition 2.C.(18). Further, administrative controls will be in place to ensure that RSP control of the valves will require deliberate action before the valves can be opened. Also, valve position indication will not be negated in the control room nor at the RSP by the imple-mentation of this special control scheme. This control scheme conforms to alternative (2)(B) provided in the NRC letter of November 22, 1985 on this subject.

The current configurations of the opening circuits for the LPCI injection valves Q1E12-F042A and Q1E12-F042B are represented schematically by Figure 1. The switch developments for the spring return handswitches located in the control room and on the remote shutdown panel are shown by Figure 2. M0V limit switch developments for the opening circuits of these valves are also depicted by Figure 2.

Figure 3 depicts the proposed addition of the two position maintained contact keylock switch (within the clouded portion of the figure). Note that the circuit is otherwise unchanged from Figure 1. Figure 4 provides the contact development for the additional switch for each of the two valve opening circuits.

This arrangement will thus provide for disabling that portion of the opening circuit for valves Q1E12-F042A and Q1E12-F0428 at the Remote Shutdown Panel until the two position keylock switch is moved to the

" enable" position. As the keylock switch will be key removable in the

" disable" position and the key maintained by administrative controls, assurance is provided that inadvertent opening of the valves will not occur.

The use of transfer switches on the RSPs has been limited to instances where the control room switch operates by maintained contacts. Other-wise, momentary contact switches are used and are spring return to

" auto." The position of the control room switches cannot compromise the remote shutdown controls. Further, the GGNS design utilizes a normally energized arrangement for the Remote Shutdown system circuits. The advantage of this design is the rapid detection of Remote Shutdown control misalignments and such detection would take place under normal operating conditions. Thus when evacuation of the control room occurs J13AECM86041803 - 4 i

• Attachment to AECM-86/0111 Page 2 of 3 assurance exists that these switches on the remote shutdown panel are in the proper position.

The remote shutdown panels are located in vital access areas which provides assurance of the security of the panels. Access to the panels is administratively controlled by locked doors and requires a keycard with the appropriate security level. Because of the security prov'ded for the RSPs and the infrequent use and access, and because of training of the operators who are authorized to use the panels, inadvertent operation of the ECCS valves from the RSP is very unlikely.

Cold shutdown from outside the control room is accomplished by manual control of the relief valves until the reactor pressure is so low that the RCIC system will discontinue operation; i.e., a reactor pressure of about 100 psig. At this point, the RHR system is operated in the shut-down cooling mode. Operation in this mode provides injection via the feedwater line. Operation of the LPCI/LPCS interface valves (F042A, B, &

C and F005) is not required to obtain cold shutdown. Thus operation of the keylock switches for the interface valves is not required, and these are the only keylock switches on the RSPs.

(2) ECCS Piping The following design considerations established the bases for determining the optimum control setpoints for the LPCI/LPCS automatic initiation pressure interlocks:

1) an upper pressure limit based on the maximum pressure allowed by the piping design code (Note: For GGNS Unit 1, the piping design code is the ASME 88PV Code Section III, 1974 Edition with Addenda through Summer,1975.);

2) a lower pressure limit based on the longest acceptable delay in initiating low pressure ECCS injection flow.

' Since the pressure interlock setpoints are double bounded by both an upper and a lower limit, the optimum value is determined as the most conservative compromise between the two competing concerns. For over-pressure protection applications, the Code (paragraphs NC-3612 and NC-7411) establishes the maximum allowable system pressure as 110% of the Design Pressure. The Design Pressures for the LPCS and LPCI piping systems are 600 psig and 500 psig, respectively. Using the limiting design pressure of 500 psig, the maximum Code allowable system pressure and the upper analytical limit for the interlock setpoint is thus 550 psig.

The lowest pressure interlock setpoint, which is limited by the longest acceptable delay in low pressure ECCS injection, is determined by the effect on fuel element peak cladding temperature (PCT) resulting from the limiting LOCA event that is most sensitive to this change. That event is the design basis accident recirculation suction line break with failure of the LPCI diesel generator. gsingaminimumpressureof436 psig, the PCT was calculated to be 2149 F.

J13AECM86041803 - 5

Attachment to AECM-86/0111 Page 3 of 3 i

With adjustments for instrument loop accuracy, calibration allowances, '

drift, system static head, and other factors, the acceptable setpoint range (based on a lower analytical limit of 436 psig and an upper analytical limit of 550 psig) was determined to be between 470 psig and 483 psig. Thus, a decrease in the upper limit by more than 13 psi would necessitate a similar decrease in the lower limit. Any decrease in the lower limit would result in an increase in the calculated PCT.

AlthoughthecalgulatedPCTisstillbelowthe10CFR50.46 acceptance criteria of 2200 F, any further increase in the PCT is not considered conservative engineering practice. Therefore, as long as the system overpressure is maintained below 110% of the Design Pressure as specified in the Code, the interlock setpoint should be established at the upper end of the acceptable range. The higher setpoint is additionally justified by an analysis of the piping system and the transient duration of an overpressure event.

An analysis was performed on the LPCI piping system and components considering a pressure equal to the upper analytical limit of the interlock setpoint (i.e. 550 psig). The analysis was performed in accordance with the ASME Code Section III, Subsection NC, Article NC-3600, considering pressure, dead weight, seismic, and other dynamic loadings (such as SRV discharge loading) for the Normal, Upset, and Faulted conditions. This analysis considered the lines to be pressurized to 550 psig. The various loading conditions were combined utilizing the methodology approved by the NRC in NUREG-0831, Supplement 2 (Grand Gulf SSER 2), Section 3.9.3. The resulting stresses were found to be within the ASME Code Allowables. Furthermore, the pressure / temperature rating for the valves, fittings, and instrument tubing were evaluated and determined to be above 550 psig for a service temperature of 575 F.

Based on the above it is concluded that structural integrity of the affected piping, valves, and components are assured for the upper analytical limit of 550 psig.

J13AECM86041803 - 6

)

ucc OP Ett ,

480V, 38, 60Hz A

8 yov 4;d E C x3 s A yuGV XI IlF lF 480-120V n1 D f flF lh 1. 6 A TB N I c y1 IIF llF 1 IHl3 IIH22 12p e 42F____ ____42R 57--O o ,

_ T - ~~ = s ' y 'a'3' G IH13' 54 '

U!

' K23A 49 13 o 42F G IHI3*

Tl" p a

y4y __ HS

~

__IC61H3 A B C ~ c.+ / t,, s, j 3" 4..- 3" Jnu_

[y[ f I U 1H13* #*" I l  : 54

- - - M IH13' l

ffh-Al BI Cl u4

" xi 2s A'21xi 20A T

444 At 81 Cl u2+

9 u2gg333 6 6 h_u_o_v y R24 30 1H13' 57k n 4iHu yin 22 IF t~TB b_TP IF Figure L h 10.3A S 42R v- b b yg o 74-37 42F 0 0

FIGURE 2 Auto k CONTACTS g g5 FUNCTION

3 1-2 X CLOSE CKT t* *2 3' '4 3-4 X OPEN CKT g g 5-6 X NOT USED s' *s 7' *a 7-s X NOT USED HANDSWITCH SPRING RETURN TO AUTO LIMIT SWITCH CONTACT DEVELOPMENT l S VALVE POSITION o

ac

• 5 FUNCTION o FULL OPEN FULL CLOSED I I4I  : ;oren ext g

- SOLID BAR INDICATES CONTACT CLOSED

uct OPEN _

480V, 30, 60Hz A

B yuov_ 4:;6 E l C XI

: n t XI vuov IIF l

IF 480-120V n\-E D f

} l 1. 6 A IIF

l - _

4TB p

. IIF llF IH13 gIH22

____42R 57 W 42F____ _

o

~~~~T~~~~* 3 ' y: ' " '

G OlHI3' 54--O Ml

" K23A 49 13 0 G o l H t 3*

pp Y 4" HS " 1CS1HS A B C CE* * ' A

• 3" A.** 3" n'."u~

l l l l W IH13*

{ 54 l _ _

_ _ _ M IH13' Ai ei

+++

~

3*''"^

1

(;D Ai ei Ci ,, o so...

A A 6..ov H21,_

x3 u y

30 01 H13' 57 - 0 j l i 91 H13 g1H22 IF l

4TB in IF FIGURE 3 k 10.3A I42R

,y b It o 42F 74-37 I

J

FlG URE 4 CoAf7 ACTS EMAkf DZ4A&LE A e eB X KEYLOCK SW M AINTAINED C ON TACT

. . . , , - . , , . - , - . . . . , , . - , , - , .