ML051250393
| ML051250393 | |
| Person / Time | |
|---|---|
| Site: | Washington State University |
| Issue date: | 05/02/2005 |
| From: | Tripard G Washington State Univ |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML051250393 (6) | |
Text
WASHINGTON STATE v UNIVERSITY Nuclear Radiation Center Washington State University Nuclear Radiation Center Pullman, Washington 99164-1300 Docket # 50-027 May 2, 2005 Document Control Desk US Nuclear Regulatory Commission Washington, DC 20555 On April 14 'h, 2005, the NLW-2 channel that had been installed since the initial criticality of the facility failed, along with its associated fission chamber. As a result, at 1600 on April 2 4 th, 2005 the Nuclear Radiation Center was unable to meet our minimum operating time requirements as stated in our security plan.
The failed Log-N channel was then replaced with a modem NLW-l000 with the help of General Atomics during the week of April 25 th, 2005. Attached are the 10 CFR 50.59 criteria for the change. Approval from our Reactor Safeguards Committee was obtained on April 22 nd, 2005, prior to replacing the failed channel.
In addition to replacing the failed channel, the associated fission chamber was replaced simultaneously. These two upgrades will allow for far greater reliability and safety in the long term operation of the reactor.
After the channel was installed and fully tested, the reactor was returned to power, and at 1700 on May 2, 2005, the facility returned to compliance with our minimum operation requirements as stated in our security plan.
PO Box 641300, Pullman, WA 99164-1300 509-335-8641
- Fax: 509-3354433
- www.wsu.eduf-nrc
If you have any comments or questions, please feel free to contact me at 509-335-0172.
Sincerely, Dr. Gerald Tripard Director, WSU NRC Cc: Marvin Mendonca, Project Manager
A. SHORT DESCRIPTION OF PROPOSED CHANGE The proposed change to the facility involves removing the current Log-N logarithmic power channel and the current Safety Channel #1, and replacing them with a new General Atomics Logarithmic Power meter, model NLW-1000. This is the final channel changeout involved in upgrading the reactor neutronic instrumentation.
B. EVALUATION TO DETERMINE IF THE PROPOSED MODIFICATION INVOLVES A TECHNICAL SPECIFICATION CHANGE OR MEETS 10 CFR 50.59 CRITERIA.
- 1. THEPROPOSEDCHANGEDOESNOTINVOLJ'EA CHANGE TO THE TECHNICAL SPECIFICATIONS The requirements for reactor monitoring channels and safety settings are listed in section 3.6.2 of the technical specifications. The requirements and proposed changes are listed below in Table 1. The requirements for reactor safety systems are listed in section 3.6.3 of the technical specifications. These requirements and the proposed changes are listed in Table 2. Since the change does not involve reducing these numbers to below the technical specification limits, the change meets this criteria.
Tablel. Measuring Channels Measuring Tech. Spec. Current Proposed Channel Requirement Number Change Steady State Mode Fuel temperature 1 2 No Change Linear power level 1 3 2 Log power level 1 1 1 Pulse Mode Fuel temperature 1 2 No Change Integrated pulse power 1 2 No Change
- 1. This installation will remove the log-n channel and the Safety Channel #1, and replace them with one logarithmic power indicating channel. This will decrease the number of linear indicators in the console. However, this change still meets the technical specifications for instrumentation.
Table 2. Reactor Safety Channels Safety Channel Function Tech. Spec. Current Proposed Requirements Number Change Steady State Mode Fuel temperature SCRAM at 500 0C 1 2 NC Power level SCRAM at 125% 1 2 2' Manual SCRAM Manual SCRAM I 1 NC Wide Range Low count rate I I 1 inhibit High Voltage SCRAM on loss of I All All Monitor High Voltage channels channels Pool level Alarm at 16' I I NC Transient rod Prevent air 1 NC control application unless fully inserted Pulse Mode Fuel temperature SCRAM at 5000C 1 2 NC Manual SCRAM Manual SCRAM I I NC Wide range High Power Pulse 1 1 1 inhibit High voltage SCRAM on loss of 1 All All monitor high voltage channels channels Pulse mode switch Prevent standard 1 1 NC rod withdrawal in pulse mode Preset timer Transient rod 1 1 NC SCRAM within 15s after pulse Pool level Alarm at 16' 1 1 NC
- 1. The Linear channel (NMP-1000) has a high power SCRAM. This will replace the SCRAM from Safety Channel #1.
- 2. THE PROPOSED CHANGE SHALL NOTRESULTIN MORE THANA MAINIMAL INCREASE IN THE FREQUENCY OR OCCURENCEOFANACCIDENTPREUIOUSL £ E[ALAUTED IN THE FSAR (As UPDATED).
There are four major accidents considered in the SAR. These are: the design base accident (fuel failure in air), a loss of coolant accident, an accidental fuel addition, and the accidental ejection of the pulse rod. Each is evaluated below.
- a. The design base accident. (Fuel failure in air.)
Several factors affect the possibility of fuel failure, including the possibility of instrument failure. However, as the instruments to be replaced are exceedingly old, and often unreliable and 'noisy' I anticipate the installation of the new instrument to be less likely to fail. This will result in an overall safety increase.
- b. The loss of coolant accident.
Coolant loss is not a result of a failure in power instrumentation. Cooling and pool level systems will remain unchanged.
- c. Accidental fuel addition.
Fuel addition has nothing to do with console controls or reactor power indication.
- d. Accidental Pulse rod ejection.
The High power pulse inhibit interlock shall be switched over to the new log channel. However, the interlock will operate in the same fashion, and the other pulse rod interlocks shall remain unchanged. This will ensure no decrease in safety of the pulse rod controls.
In addition to these postulated accidents, the SAR gives criteria for meter installation; including readability, ease of use, and connection to the SCRAM chain Since the new meter will be placed in the position of Safety Channel #1, and will be hooked up to the SCRAM chain appropriately, there will be no problem meeting these criteria.
- 3. THE PROPOSEDCHANGE SHALL NOT RESULTIN AIMORE THAN AMINIAL INCREASE IN THE LIKELIHOOD OCCURRENCE OFA MALFUNCTION OFA STRUCTURE, SISTEM, OR COMPONENT(SSC)IMPORTANT TO.SAFETYPREVIOUSLYEIALUA TED IN THE FSAR (As UPDA TED).
Since power indication is an SSC important to safety, this question must be addressed. However, as noted above, the original log-n channel has become unreliable and excessively 'noisy', and prone to spurious SCRAMs. The installation of a new channel will increase safety and reliability considerably.
- 4. THE PROPOSEDCHANGE SHALL NOTRESULTIN AORE THANA MINIMAL INCRE4SE IN THE CONSEQUANCES OFANACCIDENTPREJIVOUSLY)EJALUA TED IN THE FSAR(As UPDATED).
The results of the accidents in question are outlined in the appendix A to the SAR.
Instrumentation changes in the console should have no effect on the consequences of any of these postulated accidents.
- 5. THE PROPOSED CHANGE SHALL NOT CREATEA POSSIBILITY FOR ANACCIDENT OFA DIFFERENTTYPE THANANYPREVIOUSLY El OAL UA TED IN THE FINAL SAFETYANAL YSIS REPORT (AS UPDATED).
The replacement components have the same failure modes as the previous instrumentation. Therefore, no new accidents are postulated.
- 6. THE PROPOSED CHANGE SHALL NOT CREA TE A POSSIBILITY FOR A MALFUNCTION OFANSSC IMPORTANT TO SAFETY Ji7THA DIFFERENTRESULTTHANANY PREI IO USL YEI ALUA TED IN THE FSAR (As UPDATED).
An instrument failure of this type would result in the same problem as a failure of current instrumentation, namely incorrect power indication. These problems have already been evaluated for consequences, and no additional problem/consequence scenarios should occur with newer instrumentation.
- 7. THE PROPOSEDCHANGE SHALL NOT RESULT INA DESIGN BASIS LIMIT FOR A FISSION PRODUCTBARRIER AS DESCRIBEDIN THE SAR BEING EXCEEDED OR ALTERED..
The design limits for this reactor, as listed in section 6.3 of the SAR are shutdown margin limit, reactivity addition rate limit, fuel operating temperature limit, operating power limit, reactivity addition during pulsing, and the various fuel inspection limits. In normal operation, none of these limits will by exceeded by this upgrade.
Should the channel fail, the operating power limit could, theoretically, be exceeded. However, this possibility exists with current instrumentation, and there should be no increase in this possibility.
- 8. THE PROPOSEDCHANGE WILL NOT RESULT IN DEPARTURE FROM A METHOD OF EVALUATMON DESCIBEDAN THE SAR (As UPDATED) USEDIN ESTABLSHiNG THE DESIGNBASES ORINTHESAFETY ANALYSIS.
No such change will occur.
C. DETERMINATION OF RSC REVIEW NECESSITY Under our current procedures, any change to the facility as described in the SAR needs to be approved by the Reactor Safeguards Committee. As instrumentation is described in the SAR, this change must be approved by the RSC. New procedures will be developed for the new equipment following installation.
D. RECOMMENDATION This proposed change, in my opinion, meets the criteria for an acceptable change under 10 CFR 50.59 criteria. I hereby submit this proposal for review by the Facility Director and the RSC. Should there be any more question or comment, please feel free to contact me.
Eric Corwin, Reactor Supervisor May 2, 2005