htr-pm safety requirement and licensing experience. li fu.pdf · htr-pm safety requirement and...
TRANSCRIPT
HTR-PM Safety Requirement and Licensing Experience
Prof. Dr. LI Fu
INET, Tsinghua University, China
29 October 2014
7th International Topical Meeting on High Temperature Reactor Technology
- The modular HTR is advancing towards reality - 27-31 October 2014, Weihai, CHINA
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Contents
n HTR-PM: High temperature reactor—pebble-bed module
n 1 Project background n 2 Safety requirement n 3 Licensing process n 4 Interested topics
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1 Project background
n 2001: Feasibility study was started n 2004: Standard design was started n 2006: Basic design was started n April 2008: PSAR review was started n Sept. 2009: PSAR review was finished n Dec.9,2012: FCD of HTR-PM
n HTR-PM is scheduled to put into operation in the end of 2017
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1 Project background
n HTR-PM: first commercial modular pebble bed HTR power plant, first of a kind n Many challenges in system design and
component design n Also many challenges for licensing
n Current licensing requirement was developed mainly for/from LWR
n Lack experience for licensee and licenser
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1 Project background
n NNSA has many experiences on different type of plants n LWR for Gen II n VVER n CANDU n AP1000 n EPR
n HTR-10 experience
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2 Safety requirement
n China have a systematic nuclear safety regulation system n Laws, safety requirement (HAF), safety guide
(HAD) n Most are based on IAEA safety series
n Standards, norms n Most are based on ASME, IEEE, IEC, …
n China has most strict regulation system, combined newest requirements from different sources
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2 Safety requirement
n Current requirement is generally applicable n Especially in the level of laws, requirement,
guides n This common understanding is reached between
licensing authority and designer n Suitable standards and norms are selected
n International ASME, IEEE, IEC, and equivalent national GB, EJ, NB …
n Special: for helium property, pebble bed, ceramic internal, …, adopts KTA codes
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2 Safety requirement
n Detailed requirement is specified in design criteria, 2004-2006 n 40 chapters , for different components and
systems n Approved by NNSA
n Guideline for review is developed, issued in 2008, including: n probabilistic safety goal, PSA requirement,
VLPC, V&V, … n The technical basis is …
Safety philosophy �
n Technical basis for modular HTR n High performance TRISO fuel n High temperature core n Self acting decay heat removal n No severe accident
n Possible weak points n Less operation experience n Some rumors/doubts for dust, metal fission
product, hot spot, … 9
Safety philosophy �
n Safety function n Same requirement as other types of NPP
n Technically & Quantitatively n Control of power, removal of decay heat, retain of
fission product
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Safety philosophy �
n Safety function n Philosophy in HTR-PM project is to reduce
licensing risk n Same safety classification for pressure
boundary components n Safety class for Engineered Safety
Features (RPS, isolation valves,…) n Max fuel temperature criteria (nominal) vs.
mechanistic source term (behind) n Do no exceed the limit of 1620°C for
current design 11
Safety philosophy �
n Safety function n Philosophy in HTR-PM project is to reduce
licensing risk n Early involvement of NNSA
n Design criteria n Review guidelines n Many review, dialogue, and
consultation activities n HTR-10 licensing experiences in 1990s
n & New requirement since then �12
Safety philosophy �
n Safety goals n Both deterministic goal & probabilistic goal n Higher than before:
n Gen IV ? n Achievable
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3 Licensing process
n Early involvement n Design criteria, review guideline, …
n Review of PSAR n 1.5 years, more than 100 reviewers involved
n Dialogue & question sheet & answer sheet n 3 dialogue meetings, 8 topics reports and review
meetings, more than 2000 worksheets
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3 Licensing process
n It was a hard work for designer and licensing authority
n In Sep.2009, safety expert committee approved Preliminary Safety Evaluation Report
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4 Interested topics
n Deterministic plus probability approach n Quantitative safety goal
n Realistic, achievable n PSA: initiating events selection, design,
safety analysis, safety objective n Function of VLPC n V&V of safety software
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4 Interested topics
n Deterministic plus probabilistic approach n Deterministic requirement for DBA
n Normal operation, AOO, DBA n Special attention on LOFC, air ingress, water
ingress n Criteria are given for NO, AOO, and DBA n Analysis of ATWS are included in PSAR
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4 Interested topics
n Deterministic plus probabilistic approach n Probabilistic requirement:
n PSA, reach the probabilistic safety goal n Management of beyond design basis accident
n BDBA, not Severe accident n Additional report submitted, detailed analysis
of certain sequences n Combined with PSA n Mitigation measures were proposed
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4 Interested topics
n Quantitative safety goal n 50mSv, 10-6/reactor year
n Defined & required by NNSA n Realistic, achievable
n Technically no off-site emergency plan is needed: 50mSv, no need for evacuation
n Verified by PSA n Result is much lower than 10-6
n Within the scope of engineering judgment n Instead of 10-8, 10-10,….
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4 Interested topics
n PSA: n Combined with initiating events selection,
design, safety analysis, safety objective n Special chapter is SAR n More analysis are required for external effect,
low power level and shutdown condition, for spent fuel storage
n Directly gives out the probability of accident sequences and the release to environment
n …
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4 Interested topics
n Vented Low Pressure Containment (VLPC) n Confinement? Containment? n The term is not important, the function
requirement is key issue
n Reality: reactor cavity, with discharging burst disc, with accident ventilation system
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4 Interested topics
n Vented Low Pressure Containment (VLPC) n According to function requirement
n Supporting of safety System, Structure, Component (SSC), confinement of radioactive, reduction of radioactive release as low as reasonable achievable
n Non-safety class of accident ventilation system n According to dose result of primary circuit
break accident n VLPC is defined, and accepted
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4 Interested topics
n V&V of safety analysis software n Widely used software n V&V experience worldwide, including HTR-10 n Check the code, check the manual n Comparison calculation with other code systems n More V&V calculation on HTR-10 data n New experiment facilities
n Pebble bed equivalent conductivity coefficient n Graphite corrosion experiment n Graphite dust n …
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Conclusion remarks
n Successful experience n First Construct Permit for modular HTR n Safety: Technically no off-site emergency plan is
needed n Realistic experience
n Same safety requirement n Detailed design criteria in advance n Guideline for review in advance n Early involvement of licensing authority
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Conclusion remarks
n Main issues addressed during licensing process, important issues: n VLPC n PSA plus quantitative safety goal n Analysis and mitigation of BDBA, n V&V, n …
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Thanks for your attention !