05000346/LER-1979-029-01, /01T-2 on 790306:borated Water Storage Tank Isolation Valves DH7A & B Were Mistakenly Closed.Caused by Personnel Error.Valves Reopened & Auxiliary Operator Disciplined

/01T-2 on 790306:borated Water Storage Tank Isolation Valves DH7A & B Were Mistakenly Closed.Caused by Personnel Error.Valves Reopened & Auxiliary Operator Disciplined

ML19269E294
Person / Time
Site:	Davis Besse
Issue date:	03/16/1979
From:	David Brown TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19269E293	List: 05000346/LER-1979-029, Forwards LER 79-029/01T-2 05000346/LER-1979-029-01, /01T-2 on 790306:borated Water Storage Tank Isolation Valves DH7A & B Were Mistakenly Closed.Caused by Personnel Error.Valves Reopened & Auxiliary Operator Disciplined
References
LER-79-029-01T, LER-79-29-1T, NUDOCS 7906270178
Download: ML19269E294 (5)

LER-1979-029, /01T-2 on 790306:borated Water Storage Tank Isolation Valves DH7A & B Were Mistakenly Closed.Caused by Personnel Error.Valves Reopened & Auxiliary Operator Disciplined

Event date:
Report date:
3461979029R01 - NRC Website

text

U.S. NUCLE AR REGULATORY COMMISSION NRC FORM 3GG U 77)

LICENSEE EVENT REPORT CONTROL BL OCK: l l

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60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REFOR T D ATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h lDuring a valve lineup on 3/6/79, an Auxiliary Operator (AO) mistakenly closed Borated l

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The A0 returned and informeq lW ter Storage Tank (BWST) Isolation Valves DH7A and Dil7B.

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lthe Reactor Operator (RO) that he had closed Dil7A and Dil7B. The RO. realizinn this I

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core cooline svatom thus nlacine the unit in [g l isolated the water supply to the emergency nola tion of a Tech Spec, immediately opened DH7A and Dil7B, removing the unit from the y,g,g

nola tion.

A sarety analysis indicates the ECCS pumps would have performed their re-

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gluirca runction once tne UWST outlet valves opened automatically.

(NP-32-79-02) l D 18 I COMP.

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1-1 Valve BW7.

At 0415 hours0.0048 days <br />0.115 hours <br />6.861772e-4 weeks <br />1.579075e-4 months <br /> _

_gg DH7B instead of BWST to Borated Water Recirculation Pump frnm l

,,,, lthe R0 discovered that both DH7A and Dil7B were closed and immediatelv onaned them g

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Disciplinary action was taken against the AO.

An FCR was orenared l

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PHONE:

DVR 79-046 NAME OF PREPAHER _

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-79-02 DATE OF EVENT: March 6, 1979 FACILITY: Davis-Besse Unit 1 IDENT'rICATION OF OCCURRENCE:

Inadvertent closing of Borated Water Storage Tank (BWSI) Isolation Valves DH7A and DH7B The unit was in Mode 1, with Power (MWT) = 2384, Conditions Prior to Occurrence:

and Load (Gross MWE) = 790.

Description of Occurrence: During the 0000 to 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> shift on March 6, 1979, operations personnel were performing a valve lineup to drain down the Spent Fuel Pool per Clean Liquid Radwaste Operating Procedure, SP 1104.29, Modification T-3431.

In accordance with this modification, the Control Room Reactor Operator instructed an Auxiliary Operator to close BWST to Borated Water Recirculation Pump 1-1 Valve, BW 7.

At 04:08:25 hours, the Auxiliary Operator mistakenly closed BWST Isolation Valves DH7A and DH7B using their local switches.

At approximately 0415 hours0.0048 days <br />0.115 hours <br />6.861772e-4 weeks <br />1.579075e-4 months <br />, the Auxiliary Operator returned to the Control Room and informed the Reactor Operator that he had closed DH7A and DH7B. The Reactor in violation of a Operator realizing that closing DH7A and DH7B placed the unit Technical Specification, immediately opened DH7A and DH7B from the Control Room.

The valves were both open at 04:15:17 hours on March 6, 1979.

2l Closing DH7A and DH7B wa not in accordance with Technical Specification 3.5.2 which states that two independent Emergency Core Cooling System (ECCS) subsystems shall be operable with each subsystem comprised of one operable high pressure injection pump, one operable low pressure injection pump, one operable decay heat cooler, and one operab]t flowpath capable of taking suction from the BWST.

2l The BWST outlet valves were closed for approximately 6 minutes, 52 seconds. This report is being submitted in accordance with Technical Specification 6.9.1.8f.

Designation of Apparent Cause of Occurrence: This incident was caused by personnel An operator mistakenly closed BWST outlet valves DH7A and DH7B instead of error.

BWST to Borated Water Recirculation Pump 1-1 Valve BW 7.

There was no danger to the health and safety of the public Analysis of Occurrence:

or to station personnel. A signal from the Safety Features Actuation System would have opened DH7A and DH7B and fully restored the ECCS flowpath, but the 66 second open-ing time of the valves would have exceeded the 30 second valve safety position criteria of FSAR Section 6.3.4, "ECCS Test and Inspections".

2 2134 00f)

LER #79-029

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR P0h'ER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-32-79-02 A safety analysis completed June 15, 1979 indicates that the ECCS pumps would per-form their required function without damage af ter DH7A and DH7B opened automatically.

2 Fur thermore, the probability that a double ended break in the RCS would have occurred during the approximate seven minute interval that the valves were closed is very small.

See the attached safety evaluation for details.

Corrective Action

At 0415 hours0.0048 days <br />0.115 hours <br />6.861772e-4 weeks <br />1.579075e-4 months <br />, the Reactor Operator discovered that both DH7A and DH7B were closed and immediately opened them from the Control Room. Disciplinary action was taken against the Auxiliary Operator. Facility Change Request 79-137 was prepared to request addition of locking devices on the local control switches and 2

handwhccls of certain essential valves to prevent the valves from being repositioned from outside the Control Room.

DH7A and DH7B are included in this Facility Change Request.

Fa_ilure Data: There have been no previous similar events. There have been similar personnel errors previously reported in Licensee Event Reports NP-33-77-111, NP-33-77-ll3, and NP-33-78-08.

LER #79-029 2134 007

TOLEDO EDISON CMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE ATTACHMENT TO LICENSEE EVENT REPORT NP-32-79-02 Safety Evaluation On The Inadvertent Closure of DH7A & DH7B 1.

SAFETY EVALUATION CRITERIA The inadvertent closure of the borated water storage tank (BWST) outlet valves has been analyzed using the following criteria:

At RCS pressure less than 1650 psig or containment pressure greater than A.

4 psig, SFAS will send an "Open" signal to DH7A and DH7B (BUST outlet valves). These valves require no longer than 71 seconds to fully open.

At RCS pressure less than 1650 psig or containment pressure greater than B.

4 psig, SFAS will send a " Start" signal to the HPI pumps and an "Open" there is no signal to HP2A, HP2B, HP2C and HP2D with no time delay 11 loss of off site power (LOOP), and a 5 second time delay if there is a The HPI pumps will be at full speed and the valves will be open in LOOP.

15 seconds with no LOOP and in 30 seconds with a LOOP (5 seconds time delay, and 10 seconds Emergency Diesel Generator start additional time).

At RCS pressure less than 450 psig or containment pressure greater than C.

4 psig, SFAS will start the Decay Heat (DH) pumps with no time delay if The DH there is no LOOP and a 10 second time delay if there is a LOOP.

pumps will be at full speed in 10 seconds with no LOOP and in 30 seconds with a LOOP (10 seconds time delay and 10 seconds Emergency Diesel Genera-tor start additional time).

2 2.

ilIGH PRESSURE INJECTION PUMPS For the high pressure injection an analysis was performed to determine the effect on the response of the pumps as a result of a core flood line break.

The high pressure injection pumps are only needed for small breaks. Using the time-flow relationships calculated for the high pressure injection pump during a small break and flow with time across DH7A and DH7B it was determined there would always be sufficient Net Positive Suction Head. Therefore, that the high pressur e injection pump performance or reliability would not be de-graded.

Operation with and without offsite power was examined and pump opera-tion was found to be satisfactory in both cases.

3.

LOW PRESSURE INJECTION PUMPS For the low p. essure injection, an analysis was performed to determine the ef fect on the response of the pumps to the largest hypothesized break.

2134 008

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE ATTACHMENT TO LICENSEE EVENT REPORT NP-32-79-02 PAGE 2 Using very conservative assumptions it was found that cavitation would exist for a maximma period of 39 seconds. There is a high 1cvel of confidence that no damage would be done to the pumps based en conversations with Haywood Tyler Company engineers. Haywood Tyler purchased manufacturing rights for these pumps from Babcock and Wilcox Canada who supplied the Unit 1 pumps.

Haywood Tyler predicted no damage to these pumps under the hypothesized condi-tions because:

A.

During factory testing to determine shutoff head and net positive suction head limitations, these pumps undergo transients as severe as those hypo-thesized.

B.

Unbalanced forces will occur in the pump impeller during cavitating opera-2 t io n. However, higher forces are imposed in the pump impeller during the seismic event for which the pump is designed.

4.

CONTAINMENT SPRAY PUMPS A transient analysis was not performed for the containment spray pumps.

How-ever, by inference from the analysis' done for the low pressure injection pumps, no degradation of required flow or reliability will occur since suction line losses are lower for the containment spray pumps than for the low pressure

. injection pumpc. The net positive suction head requirements for both pumps are approximately the same. The pump vendor, Gould Pumps, has analyzed the pump operation during the transient and verified no damage to the containment spray pumps would occur.

5.

CONCLUSION These analyses indicate that the pumps would perform their required ECCS function without damage af ter DH7A and DH7B opened automatically. Further-more, the probability that a double-ended break in the RCS would have occurred during the approximate seven minute interval that these valves were closed is very small.

We conclude that this is not an unreviewed safety issue.

2134 009