ML18026A626

Reportable Occurrence 50-20/2018-1: Operation with Fewer than the Required Number of <100 Kw Nuclear Safety System Level Channel Set to Alarm; NRC OPS Center Log # EN 52157

ML18026A626
Person / Time
Site:	MIT Nuclear Research Reactor
Issue date:	01/23/2018
From:	Don S, Queirolo A Massachusetts Institute of Technology (MIT)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EN 52157, RO 50-20/2018-1
Download: ML18026A626 (3)

Text

MIT NUCLEAR REACTOR LABORATORY AN MIT INTERDEPARTMENTAL CENTER Al Queirolo Mail Stop: NW12-116 Phone: 617.258.5865 Director of Reactor Operations 138 Albany Street Fax: 617.324.0042 queiro.lomit.edu Cambridge, MA 02139 Web: http://nrl.mit.edu January 23, 2018 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: Massachusetts Institute of Technology; License No. R-37; Docket No. 50-20; Reportable Occurrence 50-20/2018-1: Operation with Fewer than the Required Number of <100 kW Nuclear Safety System Level Channel Set to Alarm; NRC OPS Center Log # EN 52157.

Dear Sir or Madam:

The Massachusetts Institute of Technology hereby submits a report of an occurrence at the MIT Research Reactor (MITR) in accordance with paragraph 7.7.2 of the Technical Specifications. An initial verbal report was made by telephone to the U.S. Nuclear Regulatory Commission Headquarters Operations Center on 9 January 2018 at 1101.

The format and content of this report was based on Regulatory Guide 1.16, Revision 1.

1. Report No. 50-20/2018-1; Ops Center Log# EN 52157 2a. Report Date: 23 January 2018 2b. Date of Occurrence: 8 January 2018

3. Facility MIT Nuclear Reactor Laboratory

4. Identification of Occurrence:

Work involving reactivity was being performed in the core on 8 January 2018 during which there was only one operable <100 kW Nuclear Safety System Level Channel set to alarm.

Technical Specification No. 3.2.3.2 requires that "fuel shall not be moved and no work involving reactivity shall be performed in the core unless the period and neutron flux level channels are set to alarm within the zero primary pump limits of Table 3.2.3-1." This table requires two operable safety system level channels to be set to alarm if neutron flux level reaches the trip set point of less than 100 kW.

5. Condition Prior to Occurrence:

The reactor was in a shutdown condition with all shim blades fully inserted and the z_,

reflector dumped. The <100 kW Startup checklist, PM 3.1.3, was completed on 8 January 2018 £EZ-in anticipation of removing two in-core experiments. The General Conduct of Refueling checklist, PM 3 .3 .1, was active to support the special procedures to remove both experiments. AIJ Z {J

Nuclear Regulatory Commission Reportable Occurrence 50-20/2018-01 23 January 2018 Page 2 of3 In anticipation of the above activities, the low-range Safety Amplifiers for the nuclear safety channels (Channels 5 & 6) were installed two weeks earlier, on Friday 22 December 2017.

6. Description of Occurrence:

At 1600 on 8 January 2018 the on-duty reactor operator noticed that the signal cable for Channel 5 <100 kW Nuclear Safety Channel was not connected to the corresponding low-range Safety Amplifier, thereby making Channel 5 inoperable. The signal cable for Channel 6's

<100 kW Nuclear Safety Channel was verified to be connected to its low-range Safety Amplifier. *

7. Description of Apparent Cause of Occurrence The Special Projects Engineer performing the swap of the Safety Amplifiers from high range to low range failed to connect the signal cable for Channel 5 once the installation was complete.

8. Analysis of Occurrence:

There is a separate high- and low-range Safety Amplifier for each Channel 5 & 6. The low-range amplifiers are used for the< 100 kW Startup Checklist and the high-range amplifiers ate used for the Full Power Startup Checklists. When shifting modes of operation per the checklists these channel amplifiers have to be disconnected, replaced and reconnected. The Special Projects Engineer disconnected Channel 6 power and signal cables, removed the high-range amplifier, installed the low-range amplifier, and reconnected the power and signal cables.

• Subsequently, the power cable for Channel 5 was disconnected. The signal cable was already removed from the high-range amplifier since the Channel 5 high-range amplifier was out of commission from the preceding operating period. Channel S's high-range amplifier was removed, the low-range amplifier was installed, and the power cable reconnected. The signal cable was not connected. All cable removals and reconnections are normally documented in the Wire Removal Forms binder located in the control room. In this instance, the Wire Removal Forms were not used to document the process. The Wire Removal Forms require a second person to verify the disconnections and reconnections of all cables.

An evaluation was performed and concluded that with all shim blades fully inserted, the automatic protective feature provided by the Safety Amplifier for each Channel 5 & 6 to drop shim blades is not needed since all shim blades are already fully inserted. The operability of the Safety Amplifier for each Channel 5 & 6 provides no additional safety function. However, without the input signal cable connection, the Channel 5 low-range Safety Amplifier was unable to provide an alarm should neutron flux level during the work in the core tank exceed the high flux trip set point, which is required by Technical Specification 3.2.3.2 to be set at less than 100 kW. The Channel 6 low-range Safety Amplifier was properly connected, and was operable and capable of providing such an alarm.

Nuclear Regulatory Commission Reportable Occurrence 50-20/2018-01 23 January 2018 Page 3 of3

9. Corrective Action:

The immediate corrective action consisted of connecting the signal cable to Channel S's low-range Safety Amplifier. The importance of using the Wire Remo"\fal Form was emphasized with the Special Projects Engineer, Shift Supervisor and Reactor Operator. The Engineer originally believed that he had completed the form but the records coulcl not be located.

Additional corrective actions are as follows:

I I

1. Install a posting on the back of each instrument panel in the control room to remind staff to complete the Wire Removal Form. (Action to be completed by 01/12/2018.)

2. Remind all staff face-to-face the importance of completing the Wire Removal Form for all evolutions. (Action to be completed by 02/09/2018.)

3. Evaluate the Technical Specifications to determine instances where requirements are not actually adding any additional safety function. Based on this evaluation, Technical Specification amendments may be considered. (Evaluation to be completed by 03/23/2018.)

4. The long-range corrective action is to complete installation of the new Mirion Wide-Range Nuclear Safety System. (Action to be completed; four to six months after NRC approval of the associated License Amendment Request.) :

10. Failure Data Related occurrences were documented in ROR 50-20/1993-1 dated 17 December 1993 and ROR 50-20/1995-2 dated 30 March 1995, both titled, "Operation with Fewer than the Required Number of <100 kW Nuclear Safety System Level Channels".

Sincerely, SarahM. Don Superintendent Q~ Director of Reactor Operations MIT Research Reactor MIT Research Reactor cc: MITRSC USNRC - Senior Project Manager Senior Reactor Inspector Research and Test Reactors Branch A Research and Test Reactors Branch B Division of Policy and Rulemaking Division of Policy and Rulemaking Office of Nuclear Reactor Regulation Office of Nuclear Reactor Regulation