05000368/LER-1984-001, :on 840128,unit Tripped During Low Power Physics Testing.Caused by One Pin Peaking Factor Limit Being Exceeded Due to Control Element Assembly Position During Testing.Procedures Modified

:on 840128,unit Tripped During Low Power Physics Testing.Caused by One Pin Peaking Factor Limit Being Exceeded Due to Control Element Assembly Position During Testing.Procedures Modified

ML20087B551
Person / Time
Site:	Arkansas Nuclear
Issue date:	02/29/1984
From:	John Marshall, Rogers P ARKANSAS POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
2CAN028408, 2CAN28408, LER-84-001, LER-84-1, NUDOCS 8403090139
Download: ML20087B551 (3)

LER-1984-001, on 840128,unit Tripped During Low Power Physics Testing.Caused by One Pin Peaking Factor Limit Being Exceeded Due to Control Element Assembly Position During Testing.Procedures Modified

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iv), System Actuation
3681984001R00 - NRC Website

text

l NRC Form 366-U.S. Nuclear Regulatory Commission (9*83)

Approved OMB No. 3150-0104 Expires: 8/31/85 LICENSEE EVENT REP 0RT (L E R)

FACILilY NAME (1) l00CAET NUMBER (2) jPAGE (3)

Arkansas Nuclear One - Unit 2 10151010101 31 61 811f0Fl012 TITLE (4)

Reactor Trip During Low Power Physics Testing EVENT DATE (5) i LER NUMBER (6) i REPORT DATE (7) l OTHER FACILITIES INVOLVEL (8) i l

i 1-lSequentiall 1Rewisioni l

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l Monthi Day lYear l Year I l Number l ! Number fMonihl Day l Year l Facility Names lCocket Number (s) i l

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l 1015l010101 1 Of 11 21 8f 81.41 81 41--! O I of I l--I O I O I01212l9?8141 101580f0f01 1 OPERATING l llHIS REPORT 15 5UBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR ):

MODE (9)

I 21 (Check one or more of the followina) (11)

PCWERI l_1 20.402(b) l _t 20.405(c) lx_1 50.74(a)(2)(iv) l _l 73.71(b)

LEVELI l_l 20.405(a)(1)(1) l_t 50.36(c)(1) l_I 50.73(a)(2)(v) l_ l 73.71(c)

(10) 1010101 1 20.405(a)(1)(ii) l_1 50.36(c)(2) l _1 50.73(a)(2)(vil) l_I Other (Specify in l_I 20.405(a)(1)(111) l_l 50.73(a)(2)(1) l _I 50.73(a)(2)(viii)(A)I Abstract below and l_l 20.405(a)(1)(iv) l_l 50.73(a)(2)(fi) l_ l 50.73(a)(2)(v111)(B)l in Text, NRC Form I l 20.405(a)(1)(v)

! i 50.73(a)(2)(itt) i I 50.73(a)(2)(x) f 36FA)

LICENSEE CONTACT FOR THIS LER (12)

Name l Telephone Number IArea l Patrick Rogers, Special Projects ;oordinator ICode l 1510l11-1916141-13111010 COMPLETE ONE L)NE FOR EACH COMPONENT FAILURE DESCRIBE 0 IN THIS REPORT (13) l l

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l l_l Yes (T; yes, complete Expected Submission Date) lxl No l DATE (15) l I I I I I ABSTRACT (Limit to 1400 spaces, i.e., approximately fifteen single-space typewritten lines) (16)

On 1/28/84 at 0831 Unit 2 tripped from ~3x10-8% FP during low power physics testing. The Core Protection Calculators (CTCs) generated an auxiliary trip when *he integrated one pin peaking factor limit as calculated by the CPCs was exceeded due to CEA position during testing without the CPCs in bypass. Initial criticality 5fter refueling was achieved using a physics testing procedure which required bypassing the CPC tr*ps to allow certain physics test to be performed. The reactor was manually tripped as part of a physics test procede.*e. When the

. reactor was returned to criticality, the normal operations procedure was used. This procedure did not contain the provisions for special test exceptions (CPC bypasses) required for physics testing. Low power physics g

testing continued without the CPCs bypassed. During the measurement of CEA group worth, group 4 rods were being inserted with all remaining rods out. At this ilme the calculated integrated one pin peak?ng factor limit was exceeded causing an auxiliary trip to be generated by the CP?s. This is an expected condition during low power physics testing and Jpecial test exceptions allow trip bypassing. Due to procedural deficiencies, the CPCs had not been bypassed..A temporary procedure change was made to delete the, step W ich rcmoves the CPCs from bypass.

No anomalies were noted following the trip.

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- o NRC Fore 366A Form 1062.018 (9-83)

U.S. Nuclear Regulatory Commission Approved OM8 No. 3150-0104 Expires: 8/31/85 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1)

IDOCKET NUMBER (2) l LER NUMBER (6) l PAGE (1) l 1 Isequentiall (Nevisioni l

l Yearf l Number f i Number l Arkansas Nuclear One - Unit 2' 10f5l010101 3l 61 81 81 4t--t 0 to i 1 1--t 0 4 0 (01210F1012 1 EXT (If more space is required, use additional NRC Form 366A's) (17)

- On 1/28/84 at. 0831 Unit 2 tripped f rom - 3 x 10-a% FP during low power physics testing.

The CPCs generated an auxiliary trip when the integrated one pin peaking factor limit as calculated by the CPCs was exceeded due to CEA position dJring testing without the CPCs in bypass.

Operatloas had achieved criticality via the " Initial Criticality Following Refueling' procedure. This procedure requires bypassing the CPCs. Physics testing was proceeding under the procedure entitled " Sequence for Low Power Physics Testing Following Refueling." Prior to executing the " Determination of Regulating CEA Group Worth" procedure, the reactor was manually tripped as required by surveillance requirements of the Technical Specification special test exceptions. This requirement provided assurance that rod insertion will occur during a trip for conditions of reduced shutdown margin.

The reactor trip was returned to critical using the normal operating procedure for " Approach to Criticality".

This procedure requires the CPC bypasses be removed prior to exceeding 10 *% FP.

Low power physics testing continued without the CPCs bypassed. During measurement of CEA group worths, group 4 rods were being inserted

'a swith all remaining rods out. This evohrtion caused the integrated one pin peakirg factor calculated by the CPCs to exceed its setpoint. This is an expected condition during low power pt/ sics testing and special test

- exceptions are provided whica allow the trip function to be blocked.

Because ci the use of the normal operating procedure for return to criticality the CPCs were not bypassed prior

.to procteding with physics testing. A temporary change was made to the " Approach to oriticality" procedure to delete the step which removes the CPCs from bypass. The reactor was returned to critical and physics testing resumed. No anomalies were noted following the trip.

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ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 LITTLE ROCK. ARKANSAS 72203 (501) 371-4fX)O February 29, 1984 2CAN028408 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.

20555 Subject: Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. NPF-6 Licensee Event Report No. 84-001-00 Gentlemen:

In accordance with Arkansas ??uclear One - Unit 2 Technical Specification 10CFR50.73(a)(2)(iv), attached is the subject report concerning a reactor trip during low power physics testing..

Very trul yours, e

O

/

John R. Marshall Manager, Licensing JRM:DRH:si Attachment cc:

Mr. John F. Streeter, Chief Reactor Project Branch #2 l

U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 3

MEMSER MtOOLE SOUTH UTIUTIES SYSTEM